Demineralization-remineralization dynamics in teeth and bone

K. M. B. Biomimetic Effect of Saliva on Human Tooth Enamel: A Scanning Electron Microscopic Study

Introduction: Due to the presence of ion reservoir, saliva may facilitate enamel remineralization and neutralize pH of acidic beverage leads to prevent enamel demineralization. Saliva substitute/artificial saliva has been developed in subsequent years and may differ in physical properties, function, or pH level from 5.0 to 7.3. Objectives: To evaluate the biomimetic effect of saliva (neutralization) on tooth enamel exposed to carbonated beverage (pH 2.44) and to observe therapeutic capability (remineralization) of artificial saliva over previously eroded (grade 3 and grade 5) enamel surface. Methods: After scanning with electron microscope (SEM-EDX), nondemineralized crown samples (n = 40) were randomly grouped into two. Samples (50%) were flushed all around to carbonated beverage with collected natural saliva bathing simultaneously (experimental group, n = 20), and the rest flushed to beverage only without saliva bathing simultaneously (control group, n = 20). Flushing action was performed for 3 min by a customized digital automatic flusher for 30 times for each sample. Samples (n = 40) were further scanned under SEM-EDX to evaluate the demineralization grade and concentration of Ca, P, O, and C elements of crown samples to find out the neutralization effect of saliva. In the second phase, already demineralized crown samples (n = 30) were randomly treated with artificial saliva having two different pH (7 or 6.8, experimental groups) and distilled water (control group) for 15 min 3 times daily for 30 days. The remineralization score of experimental samples was graded, and therapeutic capability was established. Results: Samples, when exposed to a carbonated beverage with saliva bathing simultaneously, showed low level of demineralization (mean 2.9 ± 0.3) than the control (without saliva) (mean 4.8 ± 0.3) (p = 0.01) which indicated neutralization (bioimimetic) effect of natural saliva. All (100%) of demineralized samples treated with both artificial saliva (pH 7 or pH 6.8) showed significant remineralization (p = 0.01), thus revealed biomimetic capacity. SEM-EDX analysis showed initial (before beverage exposure) concentrations of calcium, phosphorus, oxygen, and carbon elements of crown samples were 32.48%, 31.5%, 28.3%, and 5.5%, respectively. The calcium (Ca) (9.7%) and phosphorous (P) (18.5%) values were more decreased after beverage exposure without saliva bathing simultaneously compared to after beverage exposure with saliva bathing simultaneously. The concentration of oxygen (54.4%) and carbon (15.5%) were more increased after beverage exposure without saliva bathing simultaneously compared to after beverage exposure with saliva bathing simultaneously. Though the concentration of calcium (38.5%) of the crown sample was increased after treatment with artificial saliva (pH 7), but the phosphorus (18.5%) concentration of the crown sample was not increased. Conclusion: Within the context of the present study, both natural and artificial saliva showed significant biomimetic effects with respect to neutralization and remineralization.

The Impact of Calcium Overload on Cellular Processes: Exploring Calcicoptosis and Its Therapeutic Potential in Cancer

The key role of calcium in various physiological and pathological processes includes its involvement in various forms of regulated cell death (RCD). The concept of 'calcicoptosis' has been introduced as a calcium-induced phenomenon associated with oxidative stress and cellular damage. However, its definition remains controversial within the research community, with some considering it a general form of calcium overload stress, while others view it as a tumor-specific calcium-induced cell death. This review examines 'calcicoptosis' in the context of established RCD mechanisms such as apoptosis, necroptosis, ferroptosis, and others. It further analyzes the intricate relationship between calcium dysregulation and oxidative stress, emphasizing that while calcium overload often triggers cell death, it may not represent an entirely new type of RCD but rather an extension of known pathways. The purpose of this paper is to discuss the implications of this perspective for cancer therapy focusing on calcium-based nanoparticles. By investigating the connections between calcium dynamics and cell death pathways, this review contributes to the advancement of our understanding of calcicoptosis and its possible therapeutic uses.

Nano hydroxyapatite-silica with a core-shell structure for long-term management of dentin hypersensitivity

Teeth undergo continuous demineralization and remineralization influenced by dietary acid and saliva. Excessive dietary acid attack disrupts this balance, exposing dentin tubules and causing dental hypersensitivity (DH). Due to low acid resistance, traditional anti-DH regents such as calcium phosphate minerals fail in long-term occlusion of dentin tubules, resulting in recurrent attacks of DH. Hence, we fabricate nano hydroxyapatite (nHA)-silica (nHASi) with a core-shell structure that can not only fill in the dentin tubules, releasing Ca2+ and PO4 3- from the nHA core for biomineralization, but also exhibit remarkable acid resistance due to the silica shell. Our study demonstrates a continuous growth of hydroxyapatite (HA) nanocrystals within nHASi during cyclic de/remineralization. When applied with toothpaste, nHASi gradually enhances dentin tubule occlusion over de/remineralization cycles. Additionally, extracts of nHASi exhibit excellent cytocompatibility and odontogenic inductivity in vitro. This work provides a paradigm for developing effective anti-allergic materials for the long-term management of DH.

Peroxisomal dysfunction interferes with odontogenesis and leads to developmentally delayed teeth and defects in distinct dental cells in Pex11b-deficient mice

Human peroxisomal biogenesis disorders of the Zellweger syndrome spectrum affect skeletal development and induce tooth malformations. Whereas several peroxisomal knockout mouse studies elucidated the pathogenesis of skeletal defects, little information is available on how dental pathologies arise in peroxisomal biogenesis disorder patients. To understand the impact of severe peroxisomal dysfunction on early odontogenesis, here we performed morphometric studies on developing molars of new-born Pex11b knockout mice. Immunofluorescence analysis revealed reduced peroxisome number and mistargeting of the peroxisomal matrix enzyme catalase to the cytoplasm in several dental cell types of the Pex11b knockout animals. We also observed secondary mitochondrial alterations, comprising decreased staining of mitochondrial superoxide dismutase and of complex IV in cells of the developing molar. The peroxisomal defect caused by the PEX11b knockout also decreased the staining of cytokeratin intermediate filaments and of the secretory proteins amelogenin, osteopontin and osteocalcin. Interestingly, the staining of the gap junction protein connexin 43, an important modulator of tissue development, was also decreased, possibly causing the observed cellular disarrangement within the inner enamel epithelium and the odontoblast palisade. Taken together, our results show that the severe phenotype associated with the PEX11b knockout results in a reduction of the number of peroxisomes in dental cells and causes a delay odontogenesis. This adds a new component to the already described symptomatic spectrum induced by severe peroxisomal defects.

Oral Hygiene, Dietary Habits, and Saliva Properties in Relation to the Decayed, Missing, and Filled Teeth Index of Dental Students: A Pilot Study

Background and Objectives: Caries development is associated with poor oral hygiene, inadequate dietary habits, quantitative and qualitative food content, and a high level of bacterial plaque. Physical and chemical changes in saliva composition and particularly changes in its buffering capability play a significant role in caries development. This study aimed to determine the predictors of poor oral health among a sample of second-year dental students. Materials and Methods: The oral health of students was estimated with clinical examination and the DMFT index. The interview included questions about demographics status (gender, age), a dietary habits questionnaire, questions about oral hygiene, and a demonstration of tooth brushing technique. Unstimulated saliva samples were collected to measure buffering capacity and pH. Results: Almost half of the students have a low level of caries experience (46.7%), followed by a slightly smaller number having a medium level (41.3%), while one in eight students (12.0%) demonstrates a high level of caries experience. Male students have a statistically higher DMFT index 5.7 ± 1.2 than female participants 4.5 ± 0.5 (p = 0.036). Significant predictors for the DMFT index score in students were milk [β-coefficient = -0.338, p = 0.011] and yoghurt [β-coefficient = 0.284, p = 0.040] consumption. All students brushed their teeth two or more times during the day, usually after waking up before breakfast and before bedtime. Most students (85.3%) apply the proper tooth brushing technique, with female students applying it more frequently (p = 0.038). The mean salivary pH was 6.9, while the mean buffer capacity was 5.8. Female respondents have a statistically lower buffer capacity (5.8 ± 0.5) than male respondents (6.1 ± 0.4) (p = 0.047). Conclusions: Dentistry students are introduced to good oral hygiene habits, especially female students, while dietary habits should be improved. However, one in eight dental students is at high caries risk. By assessing the level of caries experience, targeted strategies can be developed to promote, maintain, and enhance oral health among dental students.

Anti-Streptococcus mutans and anti-inflammatory effects of ginsenoside Compound K and enzyme-treated red ginseng extract (BTEX-K)

OBJECTIVES

Dental caries, or tooth decay, is an oral health issue worldwide. Oral healthcare researchers are considering how to develop safe and effective preventive measures and treatments for dental caries. This study evaluated the potential applications of Compound K and BTEX-K, a Compound K-rich red ginseng extract, for the prevention and treatment of dental caries. Moreover, this study briefly confirmed its inhibitory effect on inflammation, an important factor in dental health.

METHODS

The amount of organic acids produced by bacteria in biofilm was determined using in vitro and in vivo assays. The ability of these extracts to promote tooth remineralization and microhardness was evaluated using an in vivo mouse assay. We evaluated their anti-inflammatory potential by inhibiting proinflammatory cytokine expression and lipopolysaccharide-induced nitrous oxide production in cell lines.

RESULTS

Compound K (10-20 μg/mL) and BTEX-K (50-100 μg/mL) effectively inhibited the growth of Streptococcus mutans bacteria, demonstrating significant antibacterial properties. They can potentially prevent biofilm formation by reducing lactic acid production in the teeth. These compounds showed a strong ability to promote tooth remineralization and improve the microhardness of acid-producing bacteria. They also possess potent anti-inflammatory properties that downregulate proinflammatory cytokine (interleukin-6, interleukin-1β, inducible nitric oxide synthase) expression, suppress nuclear factor-kappa B transcription factor activation (∼1.6 times), and reduce nitrous oxide production in lipopolysaccharide-induced RAW264.7 cells.

CONCLUSIONS

Compounds K and BTEX-K may provide a novel approach to dental caries prevention as well as inflammation prevention and treatment.

Comparative Evaluation of Bone-Implant Contact in Various Surface-Treated Dental Implants Using High-Resolution Micro-CT in Rabbits' Bone

This study evaluated the bone-to-implant contact (BIC) of various surface-treated dental implants using high-resolution micro-CT in rabbit bone, focusing on the effects of different treatments on osseointegration and implant stability before and after bone demineralization. Six male New Zealand White rabbits were used. Four implant types were tested: machined surface with anodizing, only etching, sandblasting with Al2O3 + etching, and sandblasting with TiO2 + etching. Implants were scanned with high-resolution micro-CT before and after demineralization. Parameters like implant volume, surface area, and BIC were determined using specific software tools. During demineralization, the BIC changed about 6% for machined surface with anodizing, 5% for only etching, 4% for sandblasting with Al2O3 + etching, and 10% for sandblasting with TiO2 + etching. Demineralization reduced BIC percentages, notably in the machined surface with anodizing and sandblasting with TiO2 + etching groups. Etching and sandblasting combined with etching showed higher initial BIC compared to anodizing alone. Demineralization negatively impacted the BIC across all treatments. This study underscores the importance of surface modification in implant integration, especially in compromised bone. Further research with larger sample sizes and advanced techniques is recommended.

Trans, Trans-Farnesol Enhances the Anti-Bacterial and Anti-Biofilm Effect of Arachidonic Acid on the Cariogenic Bacteria Streptococcus mutans and Streptococcus sobrinus

BACKGROUND

Streptococcus mutans and Streptococcus sobrinus are Gram-positive bacteria involved in the development of dental caries, as they are able to form biofilms on tooth enamel, ferment sugars into acids, and survive under acidic conditions. This ultimately leads to a local lowering of the pH value on the tooth surface, which causes enamel cavities.

HYPOTHESIS

One measure to reduce caries is to limit the growth of cariogenic bacteria by using two anti-bacterial agents with different mechanisms of action. The hypothesis of this study was that the anti-bacterial activity of ω-6 polyunsaturated arachidonic acid (AA) against S. mutans and S. sobrinus can be enhanced by the sesquiterpene alcohol trans, trans-farnesol (t,t-farnesol).

METHODS

The anti-bacterial activity of single and combined treatment was determined by the checkerboard assay. Bacterial viability was assessed by live/dead SYTO 9/propidium iodide (PI) staining on flow cytometry. Anti-biofilm activity was determined by MTT metabolic assay, crystal violet staining of biofilm biomass, SYTO 9/PI staining by spinning disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM).

RESULTS

t,t-Farnesol lowered the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of AA at sub-MICs. AA reduced the metabolic activity of preformed mature biofilms, while t,t-farnesol had no significant effect. The enhanced anti-bacterial effect of the combined t,t-farnesol/AA treatment was further evidenced by increased PI uptake, indicating membrane perforation. The enhanced anti-biofilm effect was further verified by SDCM and HR-SEM. Gene expression studies showed reduced expression of some biofilm-related genes.

CONCLUSIONS

Altogether, our study suggests a potential use of the two naturally occurring compounds arachidonic acid and t,t-farnesol for preventing biofilm formation by the cariogenic bacteria S. mutans and S. sobrinus. These findings have implications for caries prevention.

Topical fluoride varnish application shifts dysbiotic dental plaque microbiome towards eubiosis in children with dental caries

Objective

This study used high-throughput amplicon sequencing to examine the impact of long-term continuous fluoride treatment on the dental plaque microbiota of children aged 8 to 9 with mixed dentition.

Design

The study population consisted of twenty 8-9-year-old children with dental caries. Topical application of fluoride-varnish was weekly administered for one month to all subjects. Clinical indicators and anthropological data, such as the caries index (DMFT and dmft), were documented for every participant at baseline. A baseline assessment and a month after the fluoride varnish treatment were conducted for the salivary pH level and the Patient-Hygiene-Performance (PHP) index. Following application of the fluoride varnish, plaque samples were obtained both one month later and before (baseline) and were then used for 16S rRNA gene-based Next Generation Sequencing.

Results

The results showed significant differences in the community composition structure (p < 0.01). Notable caries-associated pathogens in the dental plaque microbiome were depleted whilst health associated phylum Proteobacteria was increased in the abundance following fluoride-varnish application. In children with mixed dentition, this study found that after one month of fluoride-varnish treatment, there was a significant decrease in the prevalence of the dominant pathogenic genera, Fusobacterium, Porphyromonas, Capnocytophaga, Neisseria, and Leptrotrichia, along with an increase in certain genera related to healthy oral condition, mostly from the phylum Proteobacteria, such as Areinmonas, Pseudoxanthomonas, and Luteimonas.

Conclusions

Fluoride-varnish application may shift the community level microecology from dysbiosis to eubiosis. Moreover, application of fluoride-varnish with weekly intervals for one month reduced the caries-causing bacteria while enriching the rise of unique, ubiquitous genera primarily belonging to the Proteobacteria, which may plaque a defensive role against progression of caries. Furthermore, a rising pH level towards neutrality (pH 7) indicated a healthier oral environment following the application of fluoride varnish.

The combination of arginine and fluoride-containing bioactive glass acted synergistically in inhibiting enamel demineralization in permanent teeth

OBJECTIVES

To evaluate the in-vitro efficacy of inhibiting enamel demineralization using arginine in combination with fluoride-containing bioactive glass (FBG).

METHODS

In this study, the healthy enamel blocks were first demineralized in acetic acid for 24 h, then soaked in anti-demineralization treatment solutions containing either arginine or FBG or both for 96 h.The specimens treated in acetic acid were applied as the control group. The pH, calcium and phosphorus ion concentrations of the solutions were measured before and after treatment. Changes in enamel mineral weight, microhardness, and composition were also analyzed.

RESULTS

The present of arginine facilitated fluorine release from treatment solutions with the presence of FBG. Both arginine and FBG significantly increased the pH of treatment solutions and prevented the further mineral weight loss compared to the control group. All anti-demineralization treatment groups showed significant increases in microhardness, but there was no statistical difference among the treatment groups. The SEM analysis showed enamel restoration in the arginine and FBG groups upon treatment, while the combined groups showing a superior anti-demineralization efficacy. 19F NMR showed the formation of fluorapatite in samples treated with solutions containing FBG.

CONCLUSIONS

Both arginine and FBG could inhibit enamel demineralization to some extent, and their combination demonstrated an enhanced anti-demineralization efficacy. The low-concentration combination group exhibited anti-demineralization effects comparable to those of high-concentration ones.

CLINICAL SIGNIFICANCE

This study introduces a new approach for caries prevention by combining the application of arginine and FBG. The release of fluorine promoted by the presented arginine along with calcium and phosphorus ions from FBG facilitated FAP formation. Additionally, the increment of pH resulting from arginine and FBG degradation further prevents enamel demineralization.

Unraveling Nanomaterials in Biomimetic Mineralization of Dental Hard Tissue: Focusing on Advantages, Mechanisms, and Prospects

The demineralization of dental hard tissue imposes considerable health and economic burdens worldwide, but an optimal method that can repair both the chemical composition and complex structures has not been developed. The continuous development of nanotechnology has created new opportunities for the regeneration and repair of dental hard tissue. Increasingly studies have reported that nanomaterials (NMs) can induce and regulate the biomimetic mineralization of dental hard tissue, but few studies have examined how they are involved in the different stages, let alone the relevant mechanisms of action. Besides their nanoscale dimensions and excellent designability, NMs play a corresponding role in the function of the raw materials for mineralization, mineralized microenvironment, mineralization guidance, and the function of mineralized products. This review comprehensively summarizes the advantages of NMs and examines the specific mineralization mechanisms. Design strategies to promote regeneration and repair are summarized according to the application purpose of NMs in the oral cavity, and limitations and development directions in dental hard tissue remineralization are proposed. This review can provide a theoretical basis to understand the interaction between NMs and the remineralization of dental hard tissue, thereby optimizing design strategy, rational development, and clinical application of NMs in the field of remineralization.

Impact of Calcium Lactate Pretreatment on Enamel Fluoride Uptake: A Comparative In Vitro Study of Different Fluoride Types and Concentrations

(1) Background: This study aimed to establish the effect of calcium lactate enamel pretreatment related to different fluoride types and concentrations on the enamel uptake of alkali-soluble fluorides. (2) Materials: In a blind and randomized in vitro study, a total of 60 teeth are used. The first 30 teeth were cut and randomly allocated into one of the following treatments: (A) calcium lactate pretreatment followed by three different fluoride solutions; (B) the "Fluoride only" group, with slabs treated with three different fluoride solutions; (C) the "Calcium only" group, with slabs treated with calcium lactate solution; (D) slabs treated with deionized water (negative control group). The next 30 teeth underwent all the above described group procedures but were treated with lower fluoride concentrations. Fluoride was extracted from enamel using 1 M KOH solution and analyzed using a fluoride ion-specific electrode. (3) Results: The findings revealed that slabs treated with NaF following calcium lactate pretreatment exhibited significantly greater enamel uptake of alkali-soluble fluoride compared to other substrates. This significant effect was not observed at lower fluoride concentrations. (4) Conclusion: The study demonstrates that pretreatment with calcium lactate followed by treatment with NaF at 226 ppm F significantly enhances the uptake of alkali-soluble fluoride in enamel compared to other fluoride types.

Developing a novel calcium silver zeolite for caries management

OBJECTIVE

To develop a novel calcium silver zeolite (Ca-Ag-Zeo) and assess its biocompatibility, physiochemical properties and antimicrobial effects.

METHODS

Ca-Ag-Zeo was synthesized using ion-exchange method with calcium chloride, silver nitrate and Zeolite X (Zeo). Silver zeolite X (Ag-Zeo) and Zeo were set as control. The chemical structure, morphology, crystal structure and elemental composition of Ca-Ag-Zeo was characterized by X-ray diffraction spectrum, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy, respectively. Its biocompatibility on the human gingival fibroblasts was assessed by cell counting kit-8 assay. Its physiochemical properties were determined by the released calcium and silver ion using Inductive Coupled Plasma Emission Spectrometry for up to 12 weeks. The antimicrobial properties on Streptococcus mutans, Lactobacillus acidophilus, Lactobacillus casei, and Candida albicans were assessed by minimum bactericidal concentration (MBC) or minimum fungicidal concentration (MFC) assay.

RESULTS

Ca-Ag-Zeo with a hexagonal cage structure was synthesized. As for biocompatibility, the half-maximal inhibitory concentration (± SD in mg/mL) of Ca-Ag-Zeo, Ag-Zeo and Zeo in human gingival fibroblasts were 0.52 ± 0.05, 0.15 ± 0.01 and 3.35 ± 0.58, respectively (Zeo > Ca-Ag-Zeo > Ag-Zeo; p < 0.05). As for physiochemical properties, the accumulated ion release (± SD in mg) of Ca-Ag-Zeo, Ag-Zeo and Zeo were 0.011 ± 0.003, 0 and 0 for calcium ion, respectively (Ca-Ag-Zeo > Ag-Zeo, Zeo; p < 0.001), and 0.213 ± 0.032, 0.209 ± 0.019 and 0 for silver ion, respectively (Ca-Ag-Zeo, Ag-Zeo > Zeo; p < 0.001). As for anti-microbial ability, the MBC/MFC (mg/mL) of Ca-Ag-Zeo, Ag-Zeo and Zeo were 32, 16 and > 256 against Streptococcus mutans; 32, 16, > 256 against Lactobacillus acidophilus; 16, 16, and 256 against Lactobacillus casei; 0.25, 0.125; and 2, 1, > 256 against Candida albicans, respectively.

CONCLUSION

A novel Ca-Ag-Zeo was developed. It presented better biocompatibility compared to Ag-Zeo. It released calcium and silver ions sustainably, and it could inhibit the growth of common cariogenic microorganisms.

Comparative analysis of remineralizing efficacy of strontium-doped bioactive glass, BioMin, and NovaMin containing dentifrice on artificial white spot lesions after chlorhexidine pretreatment - An in vitro study

Aim

This study aimed to compare the remineralizing efficacy of strontium-doped bioactive glass, BioMin, and NovaMin containing dentifrices on artificial white spot lesions (WSLs) after chlorhexidine (CHX) pretreatment using energy-dispersive X-ray analysis (EDAX).

Materials and Methodology

Twenty-four samples of maxillary first premolars extracted for orthodontic purposes were selected. Artificial WSLs were produced by immersing the samples in a prepared demineralizing solution for 3 days. All the samples were pretreated with CHX and divided into four groups and six samples each. Group A treated with strontium-doped bioactive glass, Group B with BioMin, Group C with NovaMin, and Group D with artificial saliva as the control group for 14 days. pH-cycling model was used to simulate the oral cavity changes. EDAX was used to record the values at baseline, demineralization, and after remineralization.

Statistical Analysis

Data were analyzed using one-way ANOVA (post hoc), followed by unpaired t-test and Scheffe tests with Statistical Package for the Social Sciences version 16.

Results

Strontium-doped bioactive glass exhibited a greater mineral regain compared to BioMin, NovaMin, and control groups.

Conclusion

Strontium-doped bioactive glass has enhanced mineral deposition on carious teeth and may provide an alternative clinical strategy for remineralizing early enamel lesions.

Surface Prereacted Glass Ionomer Varnish as a Multifaceted Anticaries Agent: Investigating its Inhibitory Effects on Demineralization and Biofilm Formation on Primary Tooth Enamel

Background

Dental caries remains a significant oral health concern, particularly in young children. With an increasing interest in preventive strategies, pediatric and preventive dentistry research is now more focused on developing newer materials and techniques to coat the primary teeth to prevent the onset of new carious lesions. While traditional preventive measures such as fluoride application and sealants have been effective in reducing caries incidence, there is still a need for innovative approaches.

Aim

To evaluate the effectiveness of surface prereacted glass ionomer (S-PRG) light-cured varnish in inhibiting demineralization of primary teeth enamel.

Materials and methods

In this study, primary teeth samples were randomly divided into two groups: the control group received no coating, while the test group received an S-PRG filler coat. The samples were allowed to demineralize, and various analyses, including Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), and Vickers microhardness analysis, were conducted. Additionally, biofilms of Streptococcus mutans and Enterococcus faecalis were developed on solid surfaces such as microtiter plates, glass, and dentures, and the quantity of bacterial biofilm was measured using crystal violet assay and fluorescence microscopy.

Results

The study results showed that the primary teeth samples in both groups had a significantly greater calcium content than the controls. The S-PRG group demonstrated a significant reduction in the development of biofilms of S. mutans and E. faecalis, as well as bacterial attachment to glass and denture surfaces compared to the control group, as indicated by crystal violet assay and fluorescence microscopy.

Conclusion

The findings of this study suggest that S-PRG filler-containing coating materials have the potential to prevent demineralization and inhibit S. mutans and E. faecalis biofilm formation on primary tooth enamel.

Clinical significance

These results are promising and may have implications for the prevention of dental caries in young children.

How to cite this article

Fernandes RM, Kumar S, Suvarna R, et al. Surface Prereacted Glass Ionomer Varnish as a Multifaceted Anticaries Agent: Investigating its Inhibitory Effects on Demineralization and Biofilm Formation on Primary Tooth Enamel. Int J Clin Pediatr Dent 2024;17(9):1049-1056.

Unveiling enamel demineralization mechanisms by sensitive dielectric differentiation based on terahertz nanospectroscopy

The early stage of dental caries, i.e. demineralization, has always been a topic of concern to dentists. Understanding the essential mechanism of its occurrence is of great significance for the prevention and treatment of dental caries. However, owing to limitations in resolution and the detection capabilities of diagnostic tools, the study of enamel demineralization has always been a challenge. Terahertz (THz) technology, especially the combination of scanning near-field optical microscopy (s-SNOM) and THz time-domain spectroscopy (TDS), due to its nanoscale resolution, has shown great advantages in the field of biological imaging. Here, a THz s-SNOM system is used to perform near-field imaging of enamel before and after demineralization at the nanoscale. It can be found that near-field signals decrease significantly after demineralization. This is due to the changes of the crystal lattice and the transfer of mineral ions during demineralization, which leads to a decrease in the permittivity of the enamel. The novel approach in this study reveals the essence of demineralization and lays the groundwork for additional research and potential interventions.

Surface and Mineral Changes of Primary Enamel after Laser Diode Irradiation and Application of Remineralization Agents: A Comparative In Vitro Study

OBJECTIVES

The purpose of this study is to evaluate the remineralization potential of primary teeth enamel after being exposed to different laser diode therapies.

METHODS

Ninety-six vestibular primary teeth enamel samples were divided into eight groups (n = 12) with varying treatments: control (G1), CPP-ACP-fluoride varnish (G2), diode lasers at 980 nm (G3), 808 nm (G4), 450 nm (G5), 980 nm + CPP-ACP-fluoride varnish (G6), 808 nm + CPP-ACP-fluoride varnish (G7), and 450 nm + CPP-ACP-fluoride varnish (G8). Each sample was assessed using a DIAGNOdent® (KaVo Dental, Biberach, Germany), at baseline, post-treatment, and post-pH cycle remineralization. SEM imaging was performed before and after treatment and following the pH cycle.

RESULTS

The results indicated that the 980 nm and 808 nm diode lasers, both alone and in combination with CPP-ACP-fluoride varnish, either maintained or increased the calcium (Ca) weight percentage (Wt%) in the enamel. The 980 nm diode laser combined with CPP-ACP-fluoride varnish (G6) showed a significant increase in Ca Wt%, suggesting a strong remineralization effect. Similarly, the 808 nm diode laser alone (G4) also promoted a substantial increase in Ca Wt%. In contrast, the 450 nm diode laser, whether applied alone or in combination with CPP-ACP-fluoride varnish, resulted in a lower Ca Wt% and an increase in phosphorus (P) Wt%. Most groups, except for the CPP-ACP-fluoride varnish alone (G2), demonstrated an increase in P Wt%, indicating a complex interaction between laser therapy and enamel remineralization.

CONCLUSIONS

The combined use of laser therapy with CPP-ACP-fluoride varnish significantly enhanced the remineralization of temporary teeth enamel. The 980 nm diode laser + CPP-ACP-fluoride varnish showed the most pronounced improvement in remineralization, while the 808 nm diode laser alone also effectively increased calcium solubility. These findings suggest that higher-wavelength diode lasers, particularly when combined with remineralizing agents, can effectively enhance the mineral content of primary teeth and promote enamel remineralization.

Exploring the Role of Hormones and Cytokines in Osteoporosis Development

The disease of osteoporosis is characterized by impaired bone structure and an increased risk of fractures. There is a significant impact of cytokines and hormones on bone homeostasis and the diagnosis of osteoporosis. As defined by the World Health Organization (WHO), osteoporosis is defined as having a bone mineral density (BMD) that is 2.5 standard deviations (SD) or more below the average for young and healthy women (T score < -2.5 SD). Cytokines and hormones, particularly in the remodeling of bone between osteoclasts and osteoblasts, control the differentiation and activation of bone cells through cytokine networks and signaling pathways like the nuclear factor kappa-B ligand (RANKL)/the receptor of RANKL (RANK)/osteoprotegerin (OPG) axis, while estrogen, parathyroid hormones, testosterone, and calcitonin influence bone density and play significant roles in the treatment of osteoporosis. This review aims to examine the roles of cytokines and hormones in the pathophysiology of osteoporosis, evaluating current diagnostic methods, and highlighting new technologies that could help for early detection and treatment of osteoporosis.

The Effects of Recreational and Pharmaceutical Substance Use on Oral Microbiomes and Health

Oral health remains one of the most taken for granted parts of human body health, even though poor oral health has now been linked to various diseases, such as cancers, diabetes, autoimmune complications, neurological disorders, and cardiovascular disease, just to name a few. As we review in this paper, substance use or abuse, including alcohol, smoking, recreational drugs, and pharmaceutical drugs can have significant implications on oral health, which in turn can lead to more systemic diseases. In this paper, we show that oral microbiome dysbiosis and inflammatory cytokine pathways are two of the most significant mechanisms contributing to oral health complications from substance use. When substance use decreases beneficial oral species and increases periodontopathogenic strains, a subsequent cascade of oncogenic and inflammatory cytokines is triggered. In this review, we explore these mechanisms and others to determine the consequences of substance use on oral health. The findings are of significance clinically and in research fields as the substance-use-induced deterioration of oral health significantly reduces quality of life and daily functions. Overall, the studies in this review may provide valuable information for future personalized medicine and safer alternatives to legal and pharmaceutical substances. Furthermore, they can lead towards better rehabilitation or preventative initiatives and policies, as it is critical for healthcare and addiction aid specialists to have proper tools at their disposal.

Veillonella parvula promotes root caries development through interactions with Streptococcus mutans and Candida albicans

Root caries is a subtype of dental caries that predominantly impacts older adults. The occurrence and progression of root caries are associated with the homeostasis of dental plaque biofilm, and microbial synergistic and antagonistic interactions in the biofilm play a significant role in maintaining the oral microecological balance. The objective of the current study was to investigate the role of Veillonella parvula in the microbial interactions and the pathogenesis of root caries. The analysis of clinical samples from patients with/without root caries revealed that Veillonella and V. parvula were abundant in the saliva of patients with root caries. More importantly, a significantly increased colonization of V. parvula was observed in root carious lesions. Further in vitro biofilm and animal study showed that V. parvula colonization increased the abundance and virulence of Streptococcus mutans and Candida albicans, leading to the formation of a polymicrobial biofilm with enhanced anti-stress capacity and cariogenicity, consequently exacerbating the severity of carious lesions. Our results indicate the critical role of V. parvula infection in the occurrence of root caries, providing a new insight for the etiological investigation and prevention of root caries.

Protecting primary teeth from dental erosion through bioactive glass

OBJECTIVES

The present study aimed to evaluate the effectiveness of bioactive glass (BAG) in preventing dental erosion in primary teeth.

METHODS

Enamel and dentin specimens (2 × 2 × 2 mm) were obtained from extracted primary teeth, which were randomly divided into the following groups based on the pretreatments (n = 12): DW (deionized water), NaF (2 % sodium fluoride), 2BAG (2 % BAG), 4BAG (4 % BAG), 6BAG (6 % BAG), and 8BAG (8 % BAG). The specimens were immersed in the respective solutions for 2 min and subjected to in vitro erosive challenges (4 × 5 min/d) for 5 d. The erosive enamel loss (EEL), erosive dentin loss (EDL), and the thickness of the demineralized organic matrix (DOM) were measured using a contact profilometer. The surface microhardness (SMH) was measured, and the percentage of SMH loss (%SMHL) was calculated. The surface morphology and mineral composition were evaluated by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively.

RESULTS

After the erosive challenges, the EEL, EDL, and%SMHL of the 2BAG, 4BAG, 6BAG, and 8BAG groups significantly reduced, with the greatest reduction was observed in the 6BAG (EEL: 6.5 ± 0.2 μm;%SMHL in enamel: 12.8 ± 2.6; EDL: 7.9 ± 0.3 μm; %SMHL in dentin: 22.1 ± 2.7) and 8BAG groups (EEL: 6.4 ± 0.4 μm;%SMHL in enamel: 11.0 ± 1.9; EDL: 7.8 ± 0.5 μm; %SMHL in dentin: 22.0 ± 2.5) (P < 0.05). With increasing BAG concentrations, the number of surface deposits containing Ca, P, and Si increased.

CONCLUSIONS

6BAG was the most effective for preventing dental erosion in primary teeth and showed a particularly strong potential for dentin erosion prevention.

CLINICAL SIGNIFICANCE

Bioactive glass, especially at a 6 % concentration, has proven effective in reducing erosive tooth wear and surface microhardness loss while also protecting demineralized organic matrix in primary dentin.

Advancing dentin remineralization: Exploring amorphous calcium phosphate and its stabilizers in biomimetic approaches

OBJECTIVE

This review elucidates the mechanisms underpinning intrafibrillar mineralization, examines various amorphous calcium phosphate (ACP) stabilizers employed in dentin's intrafibrillar mineralization, and addresses the challenges encountered in clinical applications of ACP-based bioactive materials.

METHODS

The literature search for this review was conducted using three electronic databases: PubMed, Web of Science, and Google Scholar, with specific keywords. Articles were selected based on inclusion and exclusion criteria, allowing for a detailed examination and summary of current research on dentin remineralization facilitated by ACP under the influence of various types of stabilizers.

RESULTS

This review underscores the latest advancements in the role of ACP in promoting dentin remineralization, particularly intrafibrillar mineralization, under the regulation of various stabilizers. These stabilizers predominantly comprise non-collagenous proteins, their analogs, and polymers. Despite the diversity of stabilizers, the mechanisms they employ to enhance intrafibrillar remineralization are found to be interrelated, indicating multiple driving forces behind this process. However, challenges remain in effectively designing clinically viable products using stabilized ACP and maximizing intrafibrillar mineralization with limited materials in practical applications.

SIGNIFICANCE

The role of ACP in remineralization has gained significant attention in dental research, with substantial progress made in the study of dentin biomimetic mineralization. Given ACP's instability without additives, the presence of ACP stabilizers is crucial for achieving in vitro intrafibrillar mineralization. However, there is a lack of comprehensive and exhaustive reviews on ACP bioactive materials under the regulation of stabilizers. A detailed summary of these stabilizers is also instrumental in better understanding the complex process of intrafibrillar mineralization. Compared to traditional remineralization methods, bioactive materials capable of regulating ACP stability and controlling release demonstrate immense potential in enhancing clinical treatment standards.

STMP and PVPA as Templating Analogs of Noncollagenous Proteins Induce Intrafibrillar Mineralization of Type I Collagen via PCCP Process

The phosphorylated noncollagenous proteins (NCPs) play a vital role in manipulating biomineralization, while the mechanism of phosphorylation of NCPs in intrafibrillar mineralization of collagen fibril has not been completely deciphered. Poly(vinylphosphonic acid) (PVPA) and sodium trimetaphosphate (STMP) as templating analogs of NCPs induce hierarchical mineralization in cooperation with indispensable sequestration analogs such as polyacrylic acid (PAA) via polymer-induced liquid-like precursor (PILP) process. Herein, STMP-Ca and PVPA-Ca complexes are proposed to achieve rapid intrafibrillar mineralization through polyelectrolyte-Ca complexes pre-precursor (PCCP) process. This strategy is further verified effectively for remineralization of demineralized dentin matrix both in vitro and in vivo. Although STMP micromolecule fails to stabilize amorphous calcium phosphate (ACP) precursor, STMP-Ca complexes facilely permeate into intrafibrillar interstices and trigger phase transition of ACP to hydroxyapatite within collagen. In contrast, PVPA-stabilized ACP precursors lack liquid-like characteristic and crystallize outside collagen due to rigid conformation of PVPA macromolecule, while PVPA-Ca complexes infiltrate into partial intrafibrillar intervals under electrostatic attraction and osmotic pressure as evidenced by intuitionistic 3D stochastic optical reconstruction microscopy (3D-STORM). The study not only extends the variety and size range of polyelectrolyte for PCCP process but also sheds light on the role of phosphorylation for NCPs in biomineralization.

Matrix first, minerals later: fine-tuned dietary phosphate increases bone formation in zebrafish

Bone matrix formation and mineralization are two closely related, yet separated processes. Matrix formation occurs first, mineralization is a second step strictly dependent on the dietary intake of calcium and phosphorus (P). However, mineralization is commonly used as diagnostic parameter for bone-related diseases. In this context, bone loss, often characterized as a condition with reduced bone mineral density, represents a major burden for human health, for which increased dietary mineral intake is generally recommended. Using a counterintuitive approach, we use a low-P diet followed by a sufficient-P intake to increase bone volume. We show in zebrafish by histology, qPCR, micro-CT, and enzyme histochemistry that a two-months period of reduced dietary P intake stimulates extensive formation of new bone matrix, associated with the upregulation of key genes required for both bone matrix formation and mineralization. The return to a P-sufficient diet initiates the mineralization of the abundant matrix previously deposited, thus resulting in a striking increase of the mineralized bone volume as proven at the level of the vertebral column, including vertebral bodies and arches. In summary, bone matrix formation is first stimulated with a low-P diet, and its mineralization is later triggered by a sufficient-P dietary intake. In zebrafish, the uncoupling of bone formation and mineralization by alternating low and sufficient dietary P intake significantly increases the bone volume without causing skeletal malformations or ectopic mineralization. A modification of this approach to stimulate bone formation, optimized for mammalian models, can possibly open opportunities to support treatments in patients that suffer from low bone mass.

Effect of the use of remineralization agents before resin infiltration on the treatment of initial enamel lesions: an in-vitro study

AIM

This study aimed to evaluate the effect of the use of remineralization agents before the application of resin infiltration on the treatment of initial enamel lesions.

MATERIALS AND METHODS

Eighty buccal enamel samples were prepared from human molars, and artificial initial lesions were formed after 96 h of incubation with a demineralizing solution. The samples were randomly divided into 8 groups (n = 10) including a remineralizing agent (Tooth Mousse, Medical Mineral Gel, Remin Pro), resin infiltration (ICON), and a combined treatment of both. Remineralizing agents were applied in pH cycle for 7 days. Baseline, demineralization, and after-treatment fluorescence (FluoreCam and DIAGNOdent Pen), surface microhardness (HMV-2T), surface roughness (M300C), OCT (Maestro-2) and ultrasonic system (Novascope 4500) data were obtained for all groups. The sample surfaces were examined under SEM/EDX (SU3500) at x1000. Data were statistically analyzed using the Two-Way Robust ANOVA and Bonferroni tests (p < 0.05).

RESULTS

There was no statistically significant difference between the groups for microhardness, roughness, OCT, DIAGNOdent Pen, ultrasound, and FluoreCam size/intensity values (p = 0.582; p = 0.963; p = 0.884; p = 0.923; p = 0.051; p = 0.268; p = 0.793 respectively). The effect of the treatment procedure showed a significant difference (p < 0.001), except for the roughness values (p = 0.984). The lowest Calcium (Ca) ratio (%atomic) was observed in the RI group in the EDX analysis.

CONCLUSION

Remineralizing agents and resin infiltration methods may be used in combination or alone in the treatment of initial enamel lesions. Combining remineralizing agents with resin infiltration does not alter the efficacy of the treatment.

Developing a novel glass ionomer cement with enhanced mechanical and chemical properties

OBJECTIVE

To develop a novel glass ionomer cement (NGIC) with enhanced mechanical and chemical properties and assess its biocompatibility, mechanical strength, and ion release.

METHODS

Nanosilver doped bioactive glass (NanoAg BAG) was synthesized by sol-gel method and characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy and transmission electron microscopy. The NanoAg BAG, together with poly(vinylphosphonic acid) (PVPA), alumino-fluorosilicate glass and poly-acrylic acid were used to synthesize NGIC. The optimal PVPA concentration for NGIC was determined by PVPA modified GIC's biocompatibility and mechanical properties and used to prepare NGIC specimens. NGIC specimens with NanoAg BAG at 0%, 1%, 2%, and 5% were allocated into Groups NGIC0, NGIC1, NGIC2, and NGIC5, respectively. The biocompatibility, surface morphology, elemental composition, surface topography, chemical properties, compressive strength, diametral tensile strength, and ion release of the NGIC were assessed. A conventional glass ionomer cement (GIC) was used as a control.

RESULTS

A granular BAG with nano silver particles attached on its surface were found, indicating the successful synthesis of NanoAg BAG. PVPA at 10% presented the best effect in enhancing the biocompatibility and mechanical properties of PVPA modified GIC and was used to prepare NGIC specimens. NGIC1 showed similar biocompatibility, surface morphology and topography to GIC. Chemical properties results showed that NGICs showed the same adsorption peaks to GIC. The compressive strength (mean±SD in MPa) was 168.1 ± 29.7, 205.5 ± 29.5, 221.8 ± 46.8, 216.6 ± 59.3 and 167.7 ± 36.4, and the diametral tensile strength (mean±SD in MPa) was 14.1 ± 1.7, 18.3 ± 4.9, 21.2 ± 2.2, 17.2 ± 3.8 and 13.3 ± 3.3 for GIC, NGIC0, NGIC1, NGIC2 and NGIC5 respectively. NIGC0, NGIC1 and NGIC2 showed higher compressive and diametral tensile strength than GIC (p < 0.01). NGIC2 and NGIC5 showed higher release of fluoride, calcium, phosphate and silver ion than GIC and NGIC0 (p < 0.05).

CONCLUSION

A biocompatible NGIC with enhanced mechanical properties were developed. It presented enhanced fluoride, calcium, phosphate and silver ion release compared to conventional GIC.

Development and effect of orodispersible film incorporated with Biosilicate for remineralization of dental enamel subjected to cariogenic and erosive challenge

OBJECTIVES

The objective of this in vitro study was to assess the efficiency of incorporating Biosilicate particles (30 and 50 mg) into an experimental orodispersible film and its efficacy in the remineralization process of bovine dental enamel under cariogenic and erosive challenges.

METHODS

Ninety-nine intact incisors, devoid of cracks or fractures, yielding 198 samples (6 × 6 × 2 mm) via vestibular sectioning using a low-speed diamond disc under water cooling. After flattening the enamel surface with 600, 1200, and 2000 grit sandpaper, the samples were divided into two groups based on the challenges they underwent: cariogenic (0.1 M lactic acid at pH 5.0) or erosive (0.05 M citric acid solution at pH 2.3). Samples from each challenge were further categorized into 11 groups (n = 9) according to the duration of cariogenic (3, 7, and 14 days) or erosive (3, 7, and 10 days) challenge, along with positive control groups (fragments untreated with challenges and treated with different Biosilicate concentrations) and negative controls (fragments treated with artificial saliva for the same periods established for cariogenic and erosive challenges). Treatments with orodispersible films containing Biosilicate (30 and 50 mg) were administered for 2 min per day for 15 days.

RESULTS

The highest remineralizing potential was observed in samples treated with Biosilicate after 14 days of cariogenic challenge, irrespective of the concentration tested. For samples subjected to erosive challenge, erosion time did not affect Biosilicate's remineralizing potential.

CONCLUSION

Biosilicate shows promise in terms of remineralizing potential in enamel subjected to cariogenic challenge due to its ability to form hydroxycarbonapatite in mineralized tissues.

Menopause and Oral Health: Clinical Implications and Preventive Strategies

Menopause, occurring typically between the ages of 45 and 55 years, marks the end of a woman's reproductive years and is characterized by the cessation of menstruation and a significant decline in estrogen and progesterone production. These hormonal changes impact various aspects of health, including oral health. This review explores the clinical implications of menopause on oral health and outlines preventive strategies. Hormonal changes during menopause can lead to xerostomia (dry mouth), periodontal disease, burning mouth syndrome (BMS), oral mucosal changes, altered taste sensation, and osteoporosis-related oral health issues. Xerostomia results from decreased salivary flow, increasing the risk of dental caries and oral infections. Periodontal disease is exacerbated by estrogen deficiency, leading to bone loss and increased tooth mobility. BMS, characterized by a chronic burning sensation, and oral mucosal atrophy are linked to hormonal fluctuations. In addition, altered taste perception and osteoporosis further complicate oral health management. Effective prevention and management strategies include regular dental checkups, good oral hygiene practices, and tailored treatments such as fluoride treatments, saliva substitutes, and hormone replacement therapy. Nonpharmacological approaches such as stress management and lifestyle modifications also play a role. This review emphasizes the importance of a multidisciplinary approach, involving dental and medical professionals, to address the complex oral health challenges faced by menopausal women. Understanding the underlying mechanisms and implementing evidence-based preventive measures can significantly enhance the oral health and overall well-being of menopausal women.

Evaluating the Role of Inorganic Elements of Camelus Dromedarius Saliva in Protecting Enamel Against Tooth Surface Loss

The aim of this study was to provide insight into the role of camel's saliva in protecting enamel against erosion and to evaluate the levels of salivary sodium, potassium, calcium, and phosphate ions among 2 groups of camels, those with low-grade tooth surface loss and those with high-grade tooth surface loss. Twenty-eight healthy camels, 5 males and 23 females, aged 20 months to 10 years, were divided into 2 groups. Group I comprise camels with "low-grade tooth surface loss" and Group 2 with "high-grade tooth surface loss." Unstimulated saliva was collected by a draining method. The samples were then analyzed for sodium, potassium, calcium, and phosphate concentrations using automated chemistry analysis. Data were then statistically analyzed using the unpaired Student's t-test and Pearson correlation coefficient test. The study found the salivary calcium and phosphate concentrations were significantly lower in the "high-grade" erosion group, in comparison with the other group (P < .0001 and P  =  .0257, respectively). The results also revealed that the more extensive the tooth surface loss, the more carious lesions the subject had (P  =  .023), and that caries are more common in the anterior teeth, particularly the incisors. The authors conclude that alterations in inorganic elements of saliva, particularly the calcium and phosphate ions, play a major role in the development of resistance to tooth surface loss. This work may represent a direction for future research to develop custom-made preventive supplements, which can protect camelid teeth against tooth surface loss.

What Lithuanian First-Graders Eat: Results of a 15-Year Semi-Longitudinal, Cross-Sectional Surveillance Study

This article presents the dietary habits of Lithuanian first-grade (7-8-year-old) students over a 15-year surveillance period to understand the trends and changes in their nutrition patterns. The presented data were collected from three study rounds of the Lithuanian Growth Surveillance Study conducted between 2008 and 2023, with a total sample of 11,594 first-grade students from all 10 counties of Lithuania. The main findings reveal significant shifts in breakfast consumption, with an increase in daily breakfast intake observed over the surveillance period. Conversely, the consumption of cereal porridge showed a notable decrease, particularly in the frequency of consumption. Positive changes were noted in the consumption of vegetables and fresh fruits, indicating an improvement in dietary quality. Also, a concerning trend of declining consumption of certain nutritious food groups like fish and dairy products is identified, whereas the consumption of sugary beverages is low. These findings underscore the importance of ongoing efforts to promote healthier eating habits among school-age children in Lithuania. Addressing these trends requires a multifaceted approach involving education, policy changes, and community-based interventions to ensure the long-term health and well-being of children.

Novel Resin-Based Antibacterial Root Surface Coating Material to Combat Dental Caries

Root caries caused by cariogenic bacteria are a burden on a large number of individuals worldwide, especially the elderly. Applying a protective coating to exposed root surfaces has the potential to inhibit the development of caries, thus preserving natural teeth. This study aimed to develop a novel antibacterial coating to combat root caries and evaluate its effectiveness using the antibacterial monomer dimethylaminohexadecyl methacrylate (DMAHDM). DMAHDM was synthesized and incorporated into a resin consisting of 55.8% urethane dimethacrylate (UDMA) and 44.2% TEG-DVBE (UV) at a 10% mass fraction of glass filler. Multiple concentrations of DMAHDM were tested for their impact on the resin's mechanical and physical properties. S. mutans biofilms grown on resin disks were analyzed for antibacterial efficacy. Cytotoxicity was assessed against human gingival fibroblasts (HGFs). The results showed an 8-log reduction in colony-forming units (CFUs) against S. mutans biofilm (mean ± sd; n = 6) (p < 0.05) when 5% DMAHDM was incorporated into the UV resin. There was a 90% reduction in metabolic activity and lactic acid production. A low level of cytotoxicity against HGF was observed without compromising the physical and mechanical properties of the resin. This coating material demonstrated promising physical properties, potent antibacterial effects, and low toxicity, suggesting its potential to protect exposed roots from caries in various dental procedures and among elderly individuals with gingival recession.

Material-specific binding peptides empower sustainable innovations in plant health, biocatalysis, medicine and microplastic quantification

Material-binding peptides (MBPs) have emerged as a diverse and innovation-enabling class of peptides in applications such as plant-/human health, immobilization of catalysts, bioactive coatings, accelerated polymer degradation and analytics for micro-/nanoplastics quantification. Progress has been fuelled by recent advancements in protein engineering methodologies and advances in computational and analytical methodologies, which allow the design of, for instance, material-specific MBPs with fine-tuned binding strength for numerous demands in material science applications. A genetic or chemical conjugation of second (biological, chemical or physical property-changing) functionality to MBPs empowers the design of advanced (hybrid) materials, bioactive coatings and analytical tools. In this review, we provide a comprehensive overview comprising naturally occurring MBPs and their function in nature, binding properties of short man-made MBPs (<20 amino acids) mainly obtained from phage-display libraries, and medium-sized binding peptides (20-100 amino acids) that have been reported to bind to metals, polymers or other industrially produced materials. The goal of this review is to provide an in-depth understanding of molecular interactions between materials and material-specific binding peptides, and thereby empower the use of MBPs in material science applications. Protein engineering methodologies and selected examples to tailor MBPs toward applications in agriculture with a focus on plant health, biocatalysis, medicine and environmental monitoring serve as examples of the transformative power of MBPs for various industrial applications. An emphasis will be given to MBPs' role in detecting and quantifying microplastics in high throughput, distinguishing microplastics from other environmental particles, and thereby assisting to close an analytical gap in food safety and monitoring of environmental plastic pollution. In essence, this review aims to provide an overview among researchers from diverse disciplines in respect to material-(specific) binding of MBPs, protein engineering methodologies to tailor their properties to application demands, re-engineering for material science applications using MBPs, and thereby inspire researchers to employ MBPs in their research.

The Synergistic Effect of High Intensity Focused Ultrasound on In-vitro Remineralization of Tooth Enamel by Calcium Phosphate Ion Clusters

Background

Remineralization of dental enamel is an important intervention strategy for the treatment of demineralized lesions. Existing approaches have limitations such as failure to adequately reproduce both the ideal structural and mechanical properties of the native tooth. The ability of ultrasound to control and accelerate the crystallization processes has been widely reported. Therefore, a new approach was explored for in-vitro enamel remineralization involving the synergistic effect of high-intensity focused ultrasound (HIFU) coupled with calcium phosphate ion clusters (CPICs).

Methods

The demineralized enamel was treated with CPICs, with or without subsequent HIFU exposure for different periods (2.5, 5, and 10 min). The specimens were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The surface hardness and crystallographic properties of the treated specimens were evaluated using Vickers microhardness testing and X-ray diffraction (XRD), respectively.

Results

SEM revealed distinct, organized, and well-defined prismatic structures, showing clear evidence of remineralization in the combined CPIC/HIFU treatment groups. AFM further revealed a decrease in the surface roughness values with increasing HIFU exposure time up to 5 min, reflecting the obliteration of interprismatic spaces created during demineralization. The characteristic Raman band at 960 cm-1 associated with the inorganic phase of enamel dominated well in the HIFU-treated specimens. Importantly, microhardness testing further demonstrated that new mineral growth also recovered the mechanical properties of the enamel in the HIFU-exposed groups. Critical to our aspirations for developing this into a clinical process, these results were achieved in only 5 min.

Conclusion

HIFU exposure can synergise and significantly accelerate in-vitro enamel remineralization process via calcium phosphate ion clusters. Therefore, this synergistic approach has the potential for use in future clinical interventions.

Impaired oral health: a required companion of bacterial aspiration pneumonia

Laryngotracheal aspiration has a widely-held reputation as a primary cause of lower respiratory infections, such as pneumonia, and is a major concern of care providers of the seriously ill orelderly frail patient. Laryngeal mechanical inefficiency resulting in aspiration into the lower respiratory tract, by itself, is not the cause of pneumonia. It is but one of several factors that must be present simultaneously for pneumonia to develop. Aspiration of oral and gastric contentsoccurs often in healthy people of all ages and without significant pulmonary consequences. Inthe seriously ill or elderly frail patient, higher concentrations of pathogens in the contents of theaspirate are the primary catalyst for pulmonary infection development if in an immunocompromised lower respiratory system. The oral cavity is a complex and ever changing eco-environment striving to maintain homogeneity among the numerous microbial communities inhabiting its surfaces. Poor maintenance of these surfaces to prevent infection can result inpathogenic changes to these microbial communities and, with subsequent proliferation, can altermicrobial communities in the tracheal and bronchial passages. Higher bacterial pathogen concentrations mixing with oral secretions, or with foods, when aspirated into an immunecompromised lower respiratory complex, may result in bacterial aspiration pneumonia development, or other respiratory or systemic diseases. A large volume of clinical evidence makes it clear that oral cleaning regimens, when used in caring for ill or frail patients in hospitals and long-term care facilities, drastically reduce the incidence of respiratory infection and death. The purpose of this narrative review is to examine oral health as a required causative companionin bacterial aspiration pneumonia development, and the effectiveness of oral infection control inthe prevention of this disease.

Biomimetic dentin remineralization using eggshell derived nanohydroxyapatite with and without carboxymethyl chitosan - An in vitro study

The objective of this study was to evaluate the synergistic effect of eggshell-derived nanohydroxyapatite (EnHA) and carboxymethyl chitosan (CMC) in remineralizing artificially induced dentinal lesions. EnHA and CMC were synthesized using simple chemical processes and characterized using FTIR, XRD, HRSEM-EDX, TEM, DLS and TGA/DTA analyses. A total of 64 pre-demineralized coronal dentin specimens were randomly subjected to following treatments (n = 16):artificial saliva (AS), EnHA, CMC, and EnHA-CMC, followed by pH cycling for 7 days. HRSEM-EDX, Vickers-indenter, and micro-Raman analyses were used to assess surface-topography, microhardness, and chemical analysis, respectively. All tested materials demonstrated non-cytotoxicity when assessed on hDPSCs using MTT assay. FTIR, XRD and thermal analyses confirmed the characteristics of both EnHA and CMC. EnHA showed irregular rod-shaped nanoparticles (30-70 nm) with the presence of Ca,P,Na, and Mg ions. Dentin treated with EnHA-CMC exhibited complete tubular occlusion and highest microhardness whereas the AS group revealed the least mineral deposits (p < 0.05). No significant differences were observed between EnHA and CMC groups (p > 0.05). In addition, molecular conformation analysis revealed peak intensities in collagen's polypeptide chains in dentin treated with CMC and EnHA-CMC, whereas other groups showed poor collagen stability. The results highlighted that EnHA-CMC aided in rapid and effective biomineralization, suggesting its potential as a therapeutic solution for treating dentin caries.

Comparative Evaluation of Fracture Resistance of Carbon Fiber Posts and Glass Fiber Posts in Permanent Anterior Teeth: An In Vitro Study

Introduction Dental caries and traumatic injuries often lead to tooth loss in adolescents and adults, necessitating endodontic treatment and subsequent restoration. Restoring such teeth presents a challenge due to varying degrees of substance loss. After endodontic treatment, the choice of an appropriate post is crucial for long-term stability. While metal posts are sturdy, they lack aesthetics and may cause root fractures. Fiber posts, such as carbon and glass fiber, offer improved aesthetics and mechanical properties, but their comparative performance warrants investigation. Materials and methods A total of 30 extracted anterior single-rooted teeth were divided into two groups to receive either carbon fiber or glass fiber posts. After endodontic treatment and post-space preparation, the posts were cemented using a dual polymerizing adhesive resin composite. Fracture resistance was assessed using a universal testing machine. Results The mean fracture resistance of the carbon fiber post group was recorded at 271.2 N, whereas the glass fiber post group exhibited a significantly higher mean fracture resistance of 416.133 N. This difference in fracture resistance between the two groups was found to be statistically significant (p < 0.05). Conclusion Glass fiber post systems demonstrated superior fracture resistance compared to carbon fiber post systems in anterior single-rooted teeth. These findings support the clinical preference for glass fiber posts in restoring endodontically treated anterior teeth, offering both mechanical reliability and aesthetic advantages. However, further research, including long-term clinical trials, is warranted to validate these findings and assess the overall clinical performance and longevity of fiber post systems in real-world settings.

A Comparative Evaluation of Arginine Complex Combined With Flouride and Two Standard Non-Fluoridated Remineralizing Agents: An In Vitro Study

Background Dental caries represents a dynamic process, often reversible in its early stages. Fluoride has conventionally served as the cornerstone for remineralization and early caries arrest. However, excessive fluoride intake can lead to both local and systemic toxicity. Hence, there's a pressing need to develop adjunct therapies that enhance fluoride's efficacy while minimizing its dosage. This study aims to assess and compare the remineralization potential of a novel combination comprising arginine bicarbonate and fluoride against established technologies such as Bioactive glass (NovaMin Technology; Sensodyne Repair and Protect, GlaxoSmithKline, UK) and CPP-ACP technology (GC Tooth Mousse; Tokyo Japan). Materials and methods The experiment utilized extracted premolars designated for orthodontic extraction. The initial evaluation employed the DIAGNOdentTM fluorescence method. Subsequently, teeth underwent demineralization and were measured for values. Following this, the teeth were subjected to seven cycles of remineralization, after which moment values were reassessed. Statistical analysis was performed on the recorded values. Results Participants were divided into six groups (BR-A, AR-A, BR-B, AR-B, BR-C, AR-C). T-tests demonstrated significant reductions in moment values within each group, indicating the effectiveness of all remineralizing agents. Group C exhibited the most substantial difference (-6.900 ± 0.4), followed by Group A and Group B. ANOVA analysis revealed statistically significant differences among all three groups (p=0.016). Tables showed significant distinctions between the remineralizing values of Groups A and C and Groups B and C (p=0.02 and 0.002, respectively), with no discernible distinction between Groups A and B. Conclusion The study elucidates the superior efficacy of the arginine complex with fluoride combination compared to CPP-ACP and Bioactive Glass individually. This finding underscores the potential of the novel combination therapy in enhancing remineralization while minimizing fluoride dosage, thus presenting a promising strategy for addressing early-stage dental caries.

Dynamics of Dental Enamel Surface Remineralization under the Action of Toothpastes with Substituted Hydroxyapatite and Birch Extract

To address tooth enamel demineralization resulting from factors such as acid erosion, abrasion, and chronic illness treatments, it is important to develop effective daily dental care products promoting enamel preservation and surface remineralization. This study focused on formulating four toothpastes, each containing calcined synthetic hydroxyapatite (HAP) in distinct compositions, each at 4%, along with 1.3% birch extract. Substitution elements were introduced within the HAP structure to enhance enamel remineralization. The efficacy of each toothpaste formulation was evaluated for repairing enamel and for establishing the dynamic of the remineralization. This was performed by using an in vitro assessment of artificially demineralized enamel slices. The structural HAP features explored by XRD and enamel surface quality by AFM revealed notable restorative properties of these toothpastes. Topographic images and the self-assembly of HAP nanoparticles into thin films on enamel surfaces showcased the formulations' effectiveness. Surface roughness was evaluated through statistical analysis using one-way ANOVA followed by post-test Bonferroni's multiple comparison test with a p value < 0.05 significance setting. Remarkably, enamel nanostructure normalization was observed within a short 10-day period of toothpaste treatment. Optimal remineralization for all toothpastes was reached after about 30 days of treatment. These toothpastes containing birch extract also have a dual function of mineralizing enamel while simultaneously promoting enamel health and restoration.

A Systematic Review of the Relationship between Serum Vitamin D Levels and Caries in the Permanent Teeth of Children and Adolescents

This systematic review critically evaluates the association between serum Vitamin D levels and dental caries incidence in the permanent teeth of children and adolescents. The search strategy comprised three databases (PubMed, Scopus, Embase), up to November 2023, targeting studies on the correlation between Vitamin D and dental caries in permanent dentition. The eligibility criteria focused on observational studies involving children and adolescents aged 12 to 19 years with permanent dentition. The screening process, guided by the PRISMA guidelines and the Newcastle-Ottawa Scale for quality assessment, resulted in the inclusion of eight studies conducted across various global regions from 2013 to 2023. The analysis revealed that Vitamin D insufficiency and deficiency were prevalent among the study populations, ranging from 17.3% to 69.4%. Specifically, children and adolescents with Vitamin D insufficiency (<50 nmol/L) were found to have significantly higher odds of developing caries, with odds ratios (ORs) ranging from 1.13 to 2.57. Conversely, two studies indicated a protective effect of higher Vitamin D levels, with an OR of 0.80 and 0.59, respectively, for caries among children and adolescents with serum levels ≥ 50 nmol/L, suggesting an inverse relationship between Vitamin D status and caries risk. The results indicate both the protective role of adequate serum levels of Vitamin D above 20 ng/mL and the increased risk associated with insufficient levels below this threshold. However, the variations in study quality, methodologies and geographic settings underscore the challenges in drawing universal conclusions. Despite these limitations, our review suggests that improving Vitamin D status could be a beneficial component of preventive strategies against dental caries in children and adolescents, warranting further research to clarify the clinical significance of our findings.

The erosive effect of pomegranate juice on enamel: An in vitro study

AIM

Dental erosion is a chemical-mechanical process that leads to the loss of dental hard tissues. This study aimed to investigate the effect of pomegranate juice on the enamel.

METHODS

Enamel blocks were randomly divided into three groups: deionized water, cola, and pomegranate juice. The blocks were immersed in the solutions four times a day for 14 days, and stored in artificial saliva for the remaining period. The surface hardness was measured on days 7 and 14. The surface structures of the demineralized blocks were observed via scanning electron microscopy (SEM), and the depth of demineralization was observed via confocal laser scanning microscopy (CLSM). The pH, calcium, and phosphorus levels of the three solutions were analyzed.

RESULTS

The microhardness values of the blocks in the pomegranate juice and cola groups decreased with the increase in the demineralization time. The blocks in the pomegranate juice group exhibited large fractures in the enamel column, whereas those in the cola group had pitted enamels with destruction of the interstitial enamel column. Compared with cola group, fluorescent penetration increased in pomegranate juice (P < 0.01). The pH of cola (2.32 ± 0.09) was lower than that of pomegranate juice (3.16 ± 0.16). Furthermore, the calcium content in pomegranate juice was significantly higher than that in cola (P < 0.01). Alternatively, the concentration of phosphorous in cola was significantly higher than that in pomegranate juice (P < 0.01).

CONCLUSION

These findings indicate that pomegranate juice can cause enamel demineralization with an erosive potential comparable to that of cola.

Mechanical properties of simulated dentin caries treated with metal cations and L-ascorbic acid 2-phosphate

This pH cycling study aimed to investigate the effects of L-Ascorbic acid 2-phosphate (AA2P) salts of Mg, Zn, Mn, Sr, and Ba on the surface microhardness, compressive strength, diametral tensile strength (DTS), and solubility of root canal dentin. 186 cylindrical dentin specimens from 93 teeth were fortified with optimal concentrations of AA2P salts of Mg (0.18 mM), Zn (5.3 µM), Mn (2.2 × 10-8 M), Sr (1.8 µM), and Ba (1.9 µM). Saline was used as the control group. These dentin specimens underwent a 3-day cycling process simulating dentin caries formation through repeated sequences of demineralization and remineralization. Surface microhardness at 100 and 500 µm depths (n = 10/subgroup), scanning electron microscopy (n = 3/group), compressive strength (n = 10/group), DTS (n = 6/group), and solubility (n = 5/group) tests were performed to analyze the dentin specimens. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, and Post Hoc Tukey tests (p < 0.05). The control group had significantly lower microhardness at both depths (p < 0.001), reduced DTS (p = 0.001), decreased compressive strength (p < 0.001), and higher weight loss (p < 0.001) than all other groups. The Sr group had the highest compressive strength and microhardness among all the groups. The microhardness was significantly higher for the 500 µm depth than the 100 µm depth (p < 0.001), but the difference in microhardness between depths across groups was not significant (p = 0.211). All fortifying solutions provided some protection against artificial caries lesions. Therefore, these elements might have penetrated and reinforced the demineralized dentin against acid dissolution.

Ultrastructural investigation of the effect of toothpastes containing different remineralizing agents on demineralized enamel

OBJECTIVE

The present study aimed to evaluate the effect of remineralizing agents on demineralized enamel intended for use as fluoride substitutes or supplements for oral hygiene applications.

METHODOLOGY

Enamel samples were obtained from 30 bovine teeth. The enamel blocks were stored in 20 mL of demineralization solution for 72 h. They were then brushed with the following toothpaste for the remineralization protocol: NaF, NaF/SnF2 combination, NovaMin, or nano-hydroxyapatite. SEM/EDX examinations and microhardness measurements of the samples were performed to investigate the remineralization efficacy of the studied toothpaste. One-way analysis of variance (ANOVA) with post hoc Tukey's HSD test was used to analyze the change in microhardness values in different remineralization protocols (p < 0.05).

RESULTS

Differences in the mean remineralization (%RP) and hardness recovery (%HR) were determined between the groups (p < 0.05). Groups 1 and 4 showed significant differences in %RP (p < 0.05). In the SEM/EDX examinations, the samples treated with n-HAp showed an accumulation of crystal deposits on the enamel surface, although at a lower density than those treated with NaF and NaF/SnF2 combination.

CONCLUSION

The remineralization strategy in toothpaste plays an important role in enamel remineralization. NovaMin-containing toothpaste showed positive effects on the enamel surface with better Ca/P ratio. Toothpastes containing n-HAp triggered less change in the increase of microhardness values compared to other toothpastes. The use of SnF2 in toothpaste in combination with NaF significantly increased the binding of fluoride to demineralized enamel compared to toothpaste containing NaF alone.

Natural, biphasic calcium phosphate from fish bones for enamel remineralization and dentin tubules occlusion

OBJECTIVES

A calcium phosphate extracted from fish bones (CaP-N) was evaluated for enamel remineralization and dentinal tubules occlusion.

METHODS

CaP-N was characterized by assessing morphology by SEM, crystallinity by PXRD, and composition by ICP-OES. CaP-N morphology, crystallinity, ion release, and pH changes over time in neutral and acidic solutions were studied. CaP-N was then tested to assess remineralization and dentinal tubules occlusion on demineralized human enamel and dentin specimens (n = 6). Synthetic calcium phosphate in form of stoichiometric hydroxyapatite nanoparticles (CaP-S) and tap water were positive and negative controls, respectively. After treatment (brush every 12 h for 5d and storage in Dulbecco's modified PBS), specimens' morphology and surface composition were assessed (by SEM-EDS), while the viscoelastic behavior was evaluated with microindentation and DMA.

RESULTS

CaP-N consisted of rounded microparticles (200 nm - 1 µm) composed of 33 wt% hydroxyapatite and 67 wt% β-tricalcium phosphate. In acidic solution, CaP-N released calcium and phosphate ions thanks to the preferential β-tricalcium phosphate phase dissolution. Enamel remineralization was induced by CaP-N comparably to CaP-S, while CaP-N exhibited a superior dentinal tubule occlusion than CaP-S, forming mineral plugs and depositing new nanoparticles onto demineralized collagen. This behavior was attributed to its bigger particle size and increased solubility. DMA depth profiling and SEM showed an excellent interaction between the newly formed mineralized structures and the pristine tissue, particularly at the exposed collagen fibrils.

SIGNIFICANCE

CaP-N demonstrated very good remineralizing and occlusive activity in vitro, comparable to CaP-S, thus could be a promising circular economy alternative therapeutic agent for dentistry.

Microenvironment-Driven Fenton Nanoreactor Enabled by Metal-Phenolic Encapsulation of Calcium Peroxide for Effective Control of Dental Caries

Caries are one of the most common oral diseases caused by pathogenic bacterial infections, which are widespread and persistently harmful to human health. Using nanoparticles to invade biofilms and produce reactive oxygen species (ROS) in situ is a promising strategy for killing bacteria and disrupting the structure of biofilms. In this work, a biofilm-targeting Fenton nanoreactor is reported that can generate ROS responsive to the cariogenic microenvironment. The nanoreactor is constructed by metal-phenolic encapsulation of calcium peroxide (CaO2) followed by modification with a biofilm targeting ligand dextran. Within the cariogenic biofilm, the Fenton nanoreactor is activated by an acidic microenvironment to be decomposed into H2O2 and iron ions, triggering a Fenton-like reaction to generate ROS that can eliminate the biofilm by breaking down extracellular polymeric substances (EPS) and killing cariogenic bacteria. Meanwhile, the depletion of excess protons in biofilm leads to a reversal of the cariogenic microenvironment. The Fenton nanoreactor can effectively inhibit the biofilm formation of Streptococcus mutans on ex vivo human teeth and is effective in preventing caries meanwhile maintaining the oral microbial diversity in rat caries infection model. This work provides a novel and efficient modality for acid microenvironment-driven ROS therapy.

Dairy Matrix Effects: Physicochemical Properties Underlying a Multifaceted Paradigm

When food products are often considered only as a source of individual nutrients or a collection of nutrients, this overlooks the importance of interactions between nutrients, but also interactions between nutrients and other constituents of food, i.e., the product matrix. This product matrix, which can be defined as 'The components of the product, their interactions, their structural organization within the product and the resultant physicochemical properties of the product', plays a critical role in determining important product properties, such as product stability, sensory properties and nutritional and health outcomes. Such matrix effects can be defined as 'the functional outcome of specific component(s) as part of a specific product matrix'. In this article, dairy matrix effects are reviewed, with particular emphasis on the nutrition and health impact of dairy products. Such matrix effects are critical in explaining many effects of milk and dairy products on human nutrition and health that cannot be explained solely based on nutrient composition. Examples hereof include the low glycemic responses of milk and dairy products, the positive impact on dental health, the controlled amino acid absorption and the absence of CVD risk despite the presence of saturated fatty acids. Particularly, the changes occurring in the stomach, including, e.g., coagulation of casein micelles and creaming of aggregated fat globules, play a critical role in determining the kinetics of nutrient release and absorption.

The anatomy, neurophysiology, and cellular mechanisms of intradental sensation

Somatosensory innervation of the oral cavity enables the detection of a range of environmental stimuli including minute and noxious mechanical forces. The trigeminal sensory neurons underlie sensation originating from the tooth. Prior work has provided important physiological and molecular characterization of dental pulp sensory innervation. Clinical dental experiences have informed our conception of the consequence of activating these neurons. However, the biological role of sensory innervation within the tooth is yet to be defined. Recent transcriptomic data, combined with mouse genetic tools, have the capacity to provide important cell-type resolution for the physiological and behavioral function of pulp-innervating sensory neurons. Importantly, these tools can be applied to determine the neuronal origin of acute dental pain that coincides with tooth damage as well as pain stemming from tissue inflammation (i.e., pulpitis) toward developing treatment strategies aimed at relieving these distinct forms of pain.

The power of light - From dental materials processing to diagnostics and therapeutics

Harnessing the power of light and its photonic energy is a powerful tool in biomedical applications. Its use ranges from biomaterials processing and fabrication of polymers to diagnostics and therapeutics. Dental light curable materials have evolved over several decades and now offer very fast (≤ 10 s) and reliable polymerization through depth (4-6 mm thick). This has been achieved by developments on two fronts: (1) chemistries with more efficient light absorption characteristics (camphorquinone [CQ], ~30 L mol-1 cm1 [ʎmax 470 nm]; monoacylphosphine oxides [MAPO], ~800 L mol-1 cm-1 [ʎmax 385 nm]; bisacylphosphine oxide [BAPO], ~1,000 L mol-1 cm-1 [ʎmax 385 nm]) as well mechanistically efficient and prolonged radical generation processes during and after light irradiation, and; (2) introducing light curing technologies (light emitting diodes [LEDs] and less common lasers) with higher powers (≤ 2 W), better spectral range using multiple diodes (short: 390-405 nm; intermediate: 410-450 nm; and long: 450-480 nm), and better spatial power distribution (i.e. homogenous irradiance). However, adequate cure of materials falls short for several reasons, including improper selection of materials and lights, limitations in the chemistry of the materials, and limitations in delivering light through depth. Photonic energy has further applications in dentistry which include transillumination for diagnostics, and therapeutic applications that include photodynamic therapy, photobiomodulation, and photodisinfection. Light interactions with materials and biological tissues are complex and it is important to understand the advantages and limitations of these interactions for successful treatment outcomes. This article highlights the advent of photonic technologies in dentistry, its applications, the advantages and limitations, and possible future developments.

Remineralization potential of varying concentrations of two plant-based extracts of Cocos nucifera on white spot lesions using SEM and EDAX analysis: An in vitro study

Aim

To evaluate the remineralization potential of varying concentrations of two plant-based extracts of Cocos nucifera on white spot lesions using SEM and EDAX in vitro testing methods.

Materials and Methods

The pulp was freshly obtained from coconut and divided into two. Then, coconut milk was obtained by blending, while the next portion was freeze-dried and lyophilized. Third molar teeth were processed into tooth slabs (N = 40) and split equally into five groups by block randomization. After demineralization, one tooth slab was taken from each, and SEM analysis was done. Remineralization was then performed among the various groups that included Group 1, which acted as a control and consisted of the remineralization solution. Groups 2 and 3 comprised 1:1 and 2:1 concentrations of the coconut milk, whereas Groups 4 and 5 consisted of 1:1 and 2:1 concentrations of the lyophilized extract. SEM and EDAX testing were done post-remineralization. Ca and phosphate values were tabulated, and statistical significance was determined for the obtained values using ANOVA.

Results

Among the control and treatment groups, surface remineralization was better observed in 1:1 coconut milk and 2:1 coconut milk than in the 2:1 lyophilized coconut, control, and 1:1 lyophilized coconut. Between the control and treatment groups, Ca and phosphate percentages (P < 0.001) showed statistical differences. The lowest value of 2.3% was noted in the 2:1 lyophilized coconut group.

Conclusion

Coconut extracts exhibit remineralization potential on the artificial carious lesion. Coconut milk exhibited significant improvement in the surface properties than lyophilized coconut.

Amorphous 1-D nanowires of calcium phosphate/pyrophosphate: A demonstration of oriented self-growth of amorphous minerals

Amorphous inorganic solids are traditionally isotropic, thus, it is believed that they only grow in a non-preferential way without the assistance of regulators, leading to the morphologies of nanospheres or irregular aggregates of nanoparticles. However, in the presence of (ortho)phosphate (Pi) and pyrophosphate ions (PPi) which have synergistic roles in biomineralization, the highly elongated amorphous nanowires (denoted ACPPNs) form in a regulator-free aqueous solution (without templates, additives, organics, etc). Based on thorough characterization and tracking of the formation process (e.g., Cryo-TEM, spherical aberration correction high resolution TEM, solid state NMR, high energy resolution monochromated STEM-EELS), the microstructure and its preferential growth behavior are elucidated. In ACPPNs, amorphous calcium orthophosphate and amorphous calcium pyrophosphate are distributed at separated but close sites. The ACPPNs grow via either the preferential attachment of ∼2 nm nanoclusters in a 1-dimension way, or the transformation of bigger nanoparticles, indicating an inherent driving force-governed process. We propose that the anisotropy of ACPPNs microstructure, which is corroborated experimentally, causes their oriented growth. This study proves that, unlike the conventional view, amorphous minerals can form via oriented growth without external regulation, demonstrating a novel insight into the structures and growth behaviors of amorphous minerals.

Remineralizing effects of hydroxypropyl methylcellulose film-loaded amorphous calcium phosphate nanoprecursors on enamel artificial caries lesions

OBJECTIVES

This study was to investigate hydroxypropyl methylcellulose (HPMC) film as a carrier for amorphous fluorinated calcium phosphate (AFCP) nanoprecursors to continuously deliver biomimetic remineralization of enamel artificial caries lesions (ACL).

MATERIALS AND METHODS

The AFCP/HPMC films were comprised of 25 wt% AFCP nanoparticles and 75 wt% HPMC. They were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and biocompatibility tests. Forty enamel ACL were prepared and randomly divided into four groups (n = 10): The enamel surfaces were covered with a pure HPMC film, Tooth Mousse Plus (contains 10% CPP-ACP and 0.2% NaF), and AFCP/HPMC film, or without any things (serving as negative control). Subsequently, all samples were alternatively kept in artificial saliva and a modified pH-cycling before they were characterized by Micro-CT, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), attenuated total reflectance (ATR)-FTIR, XRD, and nanoindentation.

RESULTS

After the enamel ACL was challenged by pH cycling, Tooth Mousse Plus and AFCP/HPMC film groups exhibited less lesion depth and mineral loss than the negative control and pure HPMC film groups. Additionally, the AFCP/HPMC film group revealed a highest remineralization rate of 55.34 ± 3.10 % among the all groups (p < 0.001). The SEM findings showed that the enamel ACL were densely deposited with minerals in the AFCP/HPMC film group, and the EDX results suggested a higher content of fluorine in the remineralized tissues. In particular, the AFCP/HPMC film group exhibited the best nanomechanical performance after 2 weeks of pH cycling (p < 0.05), with the hardness (H) restored from 0.29 ± 0.19 to 2.69 ± 0.70 GPa, and elastic modulus (Er) restored from 10.77 ± 5.30 to 68.83 ± 12.72 GPa.

CONCLUSION

The AFCP/HPMC film might be used as a promising strategy for arresting or reversing incipient enamel caries lesions.