Demineralization-remineralization dynamics in teeth and bone

A comparative evaluation of the effect of alcoholic and non alcoholic beverages on tooth enamel surface pretreated with β-tricalcium phosphate, bioactive glass and amine fluoride: an in vitro study

Background and aims

The aim of this in vitro study is to quantitatively evaluate the effect of different alcoholic and non alcoholic beverages on the tooth enamel surface topography pretreated with various remineralizing agents using Atomic Force Microscopy.

Methods

120 tooth specimens were prepared from 60 freshly extracted intact human premolars by sectioning from mesial to distal surfaces using low speed diamond discs and were randomly assigned to study groups and control group. Specimens of Group I, Group II and Group III were pre-treated with β-Tri calcium phosphate, bioactive glass and amine fluoride respectively for 4 minutes for 28 days, followed by storage in artificial saliva. All the specimens were evaluated for surface roughness using Atomic Force Microscopy. The specimens were then placed in alcoholic and non-alcoholic beverages for 10 minutes for 4 days and were again analyzed by Atomic Force Microscopy.Descriptive statistics was performed by using the proportional or frequency distribution of the parameters. The respondents were then grouped according to the branch of specialty if any and the data was evaluated by the one-way ANOVA with post-hoc, with p value <0.005.

Results

In the present study, among the remineralizing agents tested, bioactive glass was found to be more effective than β-Tri Calcium Phosphate and Amine Fluoride. Among the demineralizing agents used in this study, the demineralization potential of Coca Cola was found to be highest, followed by wine and green tea pretreated with β-tricalcium phosphate, bioactive glass and amine fluoride.

Conclusions

The present study concluded that all the remineralizing agents tested were found to be effective in inhibiting the demineralization caused by various alcoholic and non alcoholic beverages. Among the remineralizing agents tested, bioactive glass was found to be more effective than β-tri calcium phosphate and amine fluoride.

Effect of three different remineralising agents on prevention against acidic erosion of primary teeth: an in vitro study

PURPOSE

This study aimed to evaluate and compare the protective effect of fluoride varnish (Enamelast™, Ultradent Inc., Cologne, Germany), casein phosphopeptide-amorphous calcium phosphate fluoride/CPP-ACPF (MI Paste Plus, GC Corp., Tokyo, Japan) and self-assembling P11-4 peptide (Curodont™ Protect, Credentis AG, Windisch, Switzerland), against acidic erosion of primary teeth.

METHODS

Forty primary anterior teeth were randomly assigned to four groups (n = 10): group 1: control, group 2: fluoride varnish, group 3: CPP-ACPF and group 4: self-assembling P11-4 peptide. After applying remineralising agents, except for the control group, all specimens underwent an erosive challenge of carbonated soft drink and artificial saliva for 15 cycles of 6 s each at 6-h intervals for a day. Groups were compared in terms of surface microhardness, roughness readings, and surface scanning with an extra-oral scanner (D800; 3Shape A/S) before and after the erosive process.

RESULTS

All experimental groups showed superior results than the control group regarding microhardness, surface roughness, and substance loss. The fluoride varnish group showed significantly favourable results in microhardness change. There was no significant difference between the experimental groups regarding surface roughness and enamel loss measurements.

CONCLUSION

5% NaF fluoride varnish, CPP-ACPF and self-assembling P11-4 peptide protect the enamel of primary teeth against erosion compared to artificial saliva alone.

Remineralising potential of Ocimum basilicum varnish and fluoride varnish on initial enamel caries: An in vitro microscopic study

Background

The focus of caries research has switched to early identification and non-invasive treatment of carious lesions.

Aim

This study aimed to evaluate and compare the remineralising potential of Ocimum (O.) basilicum varnish and fluoride varnish on initial enamel caries.

Method

The authenticated O. basilicum seeds were procured from a repository, and the extract was prepared using the Soxhlet method, which was vortexed with Indian Pharmaceutical (IP)-graded chemicals to obtain varnish. Extracted premolar tooth samples were divided into three groups of 33 each after demineralisation with a pH of 4.5 for 48 hours at 37°C. Each group was subjected to remineralisation twice daily with respective agents for 4 minutes for 30 consecutive days. Each sample was ground-sectioned through an enamel window. The lesion depth was measured using a light microscope (Leica™ DM2500) and ImageJ software. The data were evaluated using analysis of variance (ANOVA) and post hoc analysis.

Results

The mean (± SD) pre-treatment lesion depth across the groups ranged from 242.11 ± 26.144 μm to 352.66 ± 34.531 μm. The highest lesion depth recovery rate of 45.938% was recorded for the fluoride varnish group, followed by 36.015% in the O. basilicum varnish group, which was statistically significant by Tukey's post hoc analysis (p < 0.001). The gingival fibroblast cells were viable by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay.

Conclusion

The O. basilicum varnish demonstrated a homogenous layer of mineral deposition. However, the remineralising efficacy was slightly lesser than that of the fluoride varnish. Hence, the novel O. basilicum-based remineralisation agent appears to have potential as a non-invasive alternative to topical fluorides in the therapy of early caries lesions.

Correlative Atomic Force Microscopy and Raman Spectroscopy in Acid Erosion of Dentin

Physical properties and chemical composition are fundamentally defining and interconnected surface characteristics. However, few techniques are able to capture both in a correlative fashion at the same sample location and orientation. This is especially important for complex materials such as dentin, which is an inner tooth structure and is a heterogeneous, composite inorganic-organic material with open channels (tubules) that extend toward the tooth pulp. Here, a combined microscope system consisting of an atomic force microscope and a confocal Raman spectrometer was used to study the correlative physical and chemical properties of human dentin. The local hardness of dentin was highly correlated with the Raman signal ratio of inorganic to organic material, and this was enhanced in the peritubular regions of dentin. When the samples were etched with citric acid, Young's modulus, hardness, and inorganic-to-organic material ratio decreased significantly, collagen fibrils on the surface were exposed, the peritubular regions were removed, and the tubule diameters increased. Thus, the combined atomic force microscopy (AFM)-Raman approach allows for comprehensive and correlative physical-chemical analysis of material surfaces and will be invaluable for evaluating oral therapeutic strategies.

Ex vivo study of molecular changes of stained teeth following hydrogen peroxide and peroxymonosulfate treatments

White teeth can give confidence and tend to be associated with a healthier lifestyle in modern society. Therefore, tooth-bleaching strategies have been developed, including the use of hydrogen peroxide. Recently, peroxymonosulfate has been introduced as an alternative bleaching method to hydrogen peroxide. Although both chemicals are oxidizing agents, their effects on the molecular composition of the stained teeth are yet unknown. In this study, the molecular profiles of teeth bleached with hydrogen peroxide and peroxymonosulfate were compared using Liquid Chromatography-Tandem Mass Spectrometry. Statistical analyses were used to assess the samples. In addition, reference spectral libraries and in silico tools were used to perform metabolite annotation. Overall, principal component analysis showed a strong separation between control and hydrogen peroxide and peroxymonosulfate samples (p < 0.001). The analysis of molecular changes revealed amino acids and dipeptides in stained teeth samples after hydrogen peroxide and peroxymonosulfate treatments. Noteworthy, the two bleaching methods led to distinct molecular profiles. For example, diterpenoids were more prevalent after peroxymonosulfate treatment, while a greater abundance of alkaloids was detected after hydrogen peroxide treatment. Whereas non-bleached samples (controls) showed mainly lipids. Therefore, this study shows how two different tooth-whitening peroxides could affect the molecular profiles of human teeth.

Development, Establishment, and Validation of a Model for the Mineralization of Periodontium Remodelling Cells: Cementoblasts

Chronic kidney disease (CKD) patients undergoing dialysis are at high risk of bone fractures. CKD-induced mineral and bone disorder is extended to periodontal disease due to changes in the ionic composition of saliva in CKD patients, dysregulating mineralization, hindering regeneration and thereby promoting the progression of dental complications. Despite the importance of cementum for overall oral health, the mechanisms that regulate its development and regeneration are not well comprehended, and a lack of sufficient in vitro experimental models has hindered research progress. In this study, the impact of experimental conditions on the calcification of cementoblasts was systematically investigated, aimed at establishing a standardized and validated model for the calcification of cementoblasts. The effects of phosphate, calcium, ascorbic acid, β-glycerolphosphate, dexamethasone, and fetal calf serum on the calcification process of cementoblasts were analyzed over a wide range of concentrations and time points by investigating calcium content, cell viability, gene expression and kinase activity. Cementoblasts calcified in a concentration- and time-dependent manner with higher concentrations of supplements cause a higher degree of calcification but decreased cell viability. Phosphate and calcium have a significantly stronger effect on cementoblast calcification processes compared to osteogenic supplements: ascorbic acid, β-glycerolphosphate, and dexamethasone induce calcification over a wide range of osteogenic signalling pathways, with osteopontin being a central target of gene regulation. Conversely, treatment with ascorbic acid, β-glycerolphosphate, and dexamethasone leads to activating only selected pathways, especially promoting bone sialoprotein expression. The developed and validated cementoblast calcification protocol, incubating up to 60% confluent cementoblasts with 1.9 mmol L-1 of phosphate supplementation for a reasonable, multi-pathway calcification induction and 10 mmol L-1 β-glycerolphosphate, 75 µmol L-1 ascorbic acid and 10 nmol L-1 dexamethasone for a reasonable osteogenic differentiation-based calcification induction, provides standard in vitro experimental models for better understanding cementoblast function and regeneration.

Comparison of microleakage under orthodontic brackets bonded with five different adhesive systems: in vitro study

BACKGROUND

Orthodontic treatment is associated with numerous adverse side effects, such as enamel discoloration, demineralization or even caries. The presence of microleakage between the enamel and the adhesive and between the adhesive and the base of the orthodontic bracket allows penetration of the bacteria, molecules, and liquids into the enamel and can lead to unpleasant "white spot lesions" or secondary caries beneath and around the brackets. The aim of this in vitro study was to evaluate microleakage in five adhesive systems commonly used in orthodontic practice for bonding brackets.

METHODS

One hundred extracted premolars were divided into five groups of twenty teeth. Stainless steel Legend medium metal brackets were bonded to teeth using five adhesive systems: resin-reinforced glass ionomer cement GC Fuji Ortho LC (GCF) and composite materials Light Bond (LB), Transbond XT (TB), Trulock™ Light Activated Adhesive (TL), and GC Ortho Connect (GCO). The specimens were subjected to thermal cycling, stained with 2% methylene blue, sectioned with low-speed diamond saw Isomet and evaluated under a digital microscope. Microleakage was detected at the enamel-adhesive and adhesive-bracket interfaces from occlusal and gingival margins. Statistical analysis was performed using generalized linear mixed models with beta error distribution.

RESULTS

Microleakage was observed in all materials, with GCF showing the highest amount of microleakage. Composite materials GCO, TB, and LB exhibited the lowest amount of microleakage with no statistical difference between them, while TL showed a statistically significantly higher amount of microleakage (p < 0.001). The enamel-adhesive interface had more microleakage in all composite materials (GCO, LB, TB, and TL) than the adhesive bracket-interface (p < 0.001). The highest amount of microleakage occurred in the gingival region in all materials.

CONCLUSION

Composite materials showed better adhesive properties than a resin-reinforced glass ionomer cement. The presence of microleakage at the enamel-adhesive interface facilitates the penetration of various substances into enamel surfaces, causing enamel demineralization and the development of dental caries.

Hereditary dentin defects with systemic diseases

OBJECTIVE

This review aimed to summarize recent progress on syndromic dentin defects, promoting a better understanding of systemic diseases with dentin malformations, the molecules involved, and related mechanisms.

SUBJECTS AND METHODS

References on genetic diseases with dentin malformations were obtained from various sources, including PubMed, OMIM, NCBI, and other websites. The clinical phenotypes and genetic backgrounds of these diseases were then summarized, analyzed, and compared.

RESULTS

Over 10 systemic diseases, including osteogenesis imperfecta, hypophosphatemic rickets, vitamin D-dependent rickets, familial tumoral calcinosis, Ehlers-Danlos syndrome, Schimke immuno-osseous dysplasia, hypophosphatasia, Elsahy-Waters syndrome, Singleton-Merten syndrome, odontochondrodysplasia, and microcephalic osteodysplastic primordial dwarfism type II were examined. Most of these are bone disorders, and their pathogenic genes may regulate both dentin and bone development, involving extracellular matrix, cell differentiation, and metabolism of calcium, phosphorus, and vitamin D. The phenotypes of these syndromic dentin defects various with the involved genes, part of them are similar to dentinogenesis imperfecta or dentin dysplasia, while others only present one or two types of dentin abnormalities such as discoloration, irregular enlarged or obliterated pulp and canal, or root malformation.

CONCLUSION

Some specific dentin defects associated with systemic diseases may serve as important phenotypes for dentists to diagnose. Furthermore, mechanistic studies on syndromic dentin defects may provide valuable insights into isolated dentin defects and general dentin development or mineralization.

Influence of Sucrose and Arenga pinnata Solutions on Enamel Surface Demineralization: A Profilometric Study

Background Dental caries is a multifactorial disease that has the potential to impact individuals across various life stages. The influential role of sugar as a contributing risk element in the inception and advancement of dental caries is significantly pronounced.  Aim The research aim was to analyze and compare the enamel surface roughness in teeth exposed to sucrose and Arenga pinnata (palm sugar) solutions by using a stylus profilometer Materials and methods In this investigation, 34 freshly extracted anterior teeth were obtained and they were split into two groups depending on the solution in which they were immersed. Group A consists of 17 teeth immersed in 1% sucrose solution supplemented in brain heart infusion (BHI) broth solution and Group B consists of 17 teeth immersed in 1% Arenga pinnata BHI broth. Each sample served as its own control. Streptococcus mutans was inoculated into these groups and they were immersed in their respective solution for five days. A stylus profilometer was utilized to measure the surface roughness of the teeth in this study. Data analysis involved paired t-tests for intragroup comparisons and independent t-tests for intergroup comparisons using SPSS software version 23. Results After five days of exposure to palm sugar or sucrose, it was observed that there was demineralization of the enamel surface on both samples. Although there was no statistical significance (p<0.05) when an independent t-test was conducted among these samples, there was a visible increase in the numerical values of Ra, Rq, Rz of teeth exposed to sucrose compared to palm sugar with a p-value of 0.529, 0.122 and 0.357, respectively. Conclusion From this study, it was concluded that although both sucrose and Arenga pinnata cause demineralization of enamel, it was shown that the latter caused lesser demineralization when compared to refined sugars to a certain extent. This study establishes a foundation for forthcoming investigations that could potentially explore the utilization of natural sugars as a substitute for sucrose, while also evaluating the mechanistic aspects underlying the impact of these sugars on enamel demineralization.

Remineralizing Ability of Resin Modified Glass Ionomers (RMGICs): A Systematic Review

The selective caries removal approach leads to the need to use materials with the ability to remineralize remaining partially demineralized dentin. Among the materials proposed are resin-modified glass ionomer cements (RMGICs). The aim of this systematic review was to evaluate, based on in vitro experimental studies, whether RMGICs are suitable for remineralizing affected dentin. A systematic literature search was performed in four databases, followed by article selection, data extraction, and quality assessment. Studies assessing the remineralizing potential of RMGICs on dentin were included in our review. Studies which compared such properties between different RMGICs or with other materials were also eligible. The studies report the remineralizing ability of RMGICs, albeit with differences between different commercial products. RMGICs show a similar ability to conventional GICs to remineralize affected dentin, fulfilling the function for which they are designed. Moreover, the incorporation of additives, such as bioactive glass (BAG) or CCP-ACP, improves their remineralizing potential. The results of this review support the use of RMGICs as restorative materials after selective caries removal.

Preclinical Evaluation of a Protein-Based Nanoscale Contrast Agent for MR Angiography at an Ultralow Dose

PURPOSE

BSA-biomineralized Gd nanoparticles (Gd@BSA NPs) have been recognized as promising nanoscale MR contrast agents. The aim of this study was to carry out a preclinical evaluation of these NPs in a middle-sized animal model (rabbits).

METHODS

New Zealand white rabbits were treated intravenously with Gd@BSA NPs (0.02 mmol Gd/kg) via a clinically-used high-pressure injector, with commercial Gd-diethylene triamine pentaacetate (Gd-DTPA)-injected group as control. Then MR angiography was performed according to the standard clinical protocol with a 3.0-T MR scanner. The SNR and CNR of the main arteries and branches were monitored. Pharmacokinetics and bioclearance were continuously evaluated in blood, urine, and feces. Gd deposition in vital organs was measured by ICP‒MS. Weight monitoring, HE staining, and blood biochemical analysis were also performed to comprehensively estimate systemic toxicity.

RESULTS

The ultrasmall Gd@BSA NPs (<6 nm) exhibited high stability and T1 relaxivity. Compared to Gd-DTPA, Gd@BSA NPs demonstrated superior vascular system imaging performance at ultralow doses, especially of the cardiac artery and other main branches, and exhibited a significantly higher SNR and CNR. Notably, the Gd@BSA NPs showed a shorter half-life in blood, less retention in organs, and improved biocompatibility.

CONCLUSION

The preclinical evaluations here demonstrated that Gd@BSA NPs are promising and advantageous MR CA candidates that can be used at a low dose with excellent MR imaging performance, thus suggesting its further clinical trials and applications.

Early Implant Bone Loss in the Preprosthetic Phase: A Retrospective Study

Initiation of the inflammatory response begins with the surgical placement of an implant that stimulates bone remodeling. The occurrence of crestal bone loss during submerged healing affects the prognosis of an implant. Hence, this study was conducted to estimate the early implant bone loss during the preprosthetic phase on bone level implants placed equicrestally. This retrospective observational study included evaluation of crestal bone loss around 271 two-piece implants placed in 149 patients from the archived postsurgical (P1) and preprosthetic (P2) digital orthopantomographic records using MicroDicom software. The outcome was categorized based on (1) sex (male or female), (2) time of implant placement (immediate [I] vs conventional [D]), (3) duration of healing period before loading (conventional [T1] vs delayed [T2]), (4) region of implant placement (maxilla [M1] vs mandible [M2]), and (5) site of implant placement (anterior [A] vs posterior [P]). To find the significant difference between the bivariate samples in the independent groups, an unpaired sample t test was used. The average marginal bone loss during the healing phase was 0.56 ± 0.573 mm in the mesial region and 0.44 ± 0.549 mm in the distal region of the implant, with a statistically significant difference (P < .01). There was no statistically significant difference in crestal bone level with the (1) sex of the patient (male or female), (2) type of implant placement (I or D), (3) time of implant loading (T1 or T2), (4) region of implant placement (M1 or M2), or (5) site of implant in the arch (A or P) (P > .05). An average of 0.50 mm crestal bone loss occurred in the peri-implant region during the preprosthetic phase. We found that the delayed placement of an implant and a delay in the healing period would further increase the early implant bone loss. The difference in the healing period did not alter the outcome of the study.

A Systematic Review on the Effect of Strontium-Doped Nanohydroxyapatite in Remineralizing Early Caries Lesion

The aim of this study is to review the potential of strontium-doped nanohydroxyapatite (SrnHAP) as a biomaterial for remineralizing early carious lesions. Publications from 2012 to 2022 were included based on the patient/population, intervention, comparison, and outcomes (PICO) framework, focusing on demineralized enamel treated with strontium-doped nanohydroxyapatite compared to other remineralizing agents, with the primary outcome being remineralization capacity. Electronic databases, namely, PubMed, Cochrane Library, and Google Scholar, were explored from March 31, 2023, to April 10, 2023. Only English language studies were included, while certain research types and studies on bovine teeth were excluded. Bias was assessed using the Cochrane methodology. Five studies were synthesized, all using extracted human maxillary premolars. Four studies focused on remineralizing enamel, while one study focused on remineralizing dentin. Among these studies, comparisons were made between different strontium concentrations and various remineralizing agents such as nanohydroxyapatite (nHAP), Acclaim, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and NovaMin. X-ray diffraction analysis was used to examine hydroxyapatite formation, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization. Additionally, one study evaluated the mechanical properties of partially demineralized dentin specimens. This study was registered in the PROSPERO under the ID CRD42023397413 and completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Release Kinetics of Monomers from Dental Composites Containing Fluoride-Doped Calcium Phosphates

This study analyse the type of release kinetic of specific monomers from dental resin composites containing various fluoride-doped calcium phosphates. The release behavior of urethane dimethacrylate (UDMA), ethoxylated bisphenol-A dimethacrylate (bis-EMA) and 1.6-hexanediol ethoxylate diacrylate (HEDA) was evaluated over a period of 35 days. Two tailored calcium phosphates doped with different concentrations of fluoride salts (VS10% and VS20%) were prepared and incorporated in the dimethacrylate matrix at various concentrations to generate a range of experimental composites. The release kinetics were characterized using mathematical models such as zero-order, first-order, Peppas and Higuchi models. The results showed that the first-order model best described the release kinetics. UDMA and HEDA exhibited significant differences in release compared to bis-EMA from day 1, while no significant differences were observed between UDMA and HEDA, except on day 35, when UDMA exhibited a higher release rate than HEDA. When comparing the release of each monomer, VS20-R20% had the highest total release percentage, with 3.10 ± 0.25%, whereas the composite VS10-R5% showed the lowest release percentage, with a total of 1.66 ± 0.08%. The release kinetics were influenced by the composition of the resin composites and the presence of calcium fluoride and sodium fluoride in the calcium phosphate played a role in the maximum amounts of monomer released. In conclusion, the release of monomers from the tested resin composites followed a first-order kinetic behaviour, with an initial rapid release that decreased over time. The composition of the resin monomers and the presence of fluoride salts influenced the release kinetics. The VS10-R5% and VS10-R10% resin composites exhibited the lowest total monomer release, suggesting its potential favourable composition with reduced monomer elution. These findings contribute to understanding the release behavior of dental resin composites and provide insights for the development of resin-based bioactive dental materials.

Antibacterial Effect of Miswak herbal toothpaste Compared to Fluoride Toothpaste in High Caries Risk Patients: Randomized Clinical Trial

Background

Modern toothbrushes origin can be traced to plant-derived chewing sticks, which were documented to be used Babylonians as early as 3500 BC. Chewing sticks are routinely used for cleaning teeth in Asia, Africa, South America, and the Middle East. The aim of the current study was to evaluate the antibacterial effect of miswak herbal toothpaste compared to fluoride toothpaste using a normal toothbrush, against Streptococcus mutans in high caries risk patients.

Material and Methods

A total of 32 participants were recruited to the current clinical trial using convenience sampling randomly either to miswak or fluoride toothpastes groups (n=16). The bacterial count represented as colony-forming units per milliliter (CFU/ml) was assessed at baseline and after 1 week, 1 month and 3 months. Moreover, the ion release for silicone, calcium, phosphorus, and fluoride from both toothpastes was analyzed in addition to the pH of both toothpastes and their supernatants. Intergroup comparison was performed using independent t test, while intragroup comparison was performed using repeated measures ANOVA followed by tukey post-hoc test and paired t test when appropriate.

Results

There was no statistically significant difference between both toothpastes for the S. mutans count within each follow up period, however the bacterial count significantly decreased over time in both groups. Signal Fluoride toothpaste exhibited statistically significant higher ion release when compared to the Dabur Miswak toothpaste. There was no statistically significant difference between either toothpastes regarding pH (P = 0.5368), while comparison between supernatants of toothpastes have shown statistically significant difference (P = 0.0194), with a higher pH in miswak toothpaste.

Conclusions

Miswak herbal toothpaste possesses a potent antibacterial effect, yet its remineralization potential is questionable due to its inferior ion release that will affect the ion substantivity in saliva, which is an important factor in remineralization. Key words:High caries risk, Miswak, Fluoride, Antibacterial, Streptococcus mutans.

Effectiveness of amine fluoride mouthwash in preventing white spot lesions during fixed orthodontic therapy - A randomized control trial

Background and Aim

One of the main reasons that patients seek orthodontic treatment is aesthetics. Unfortunately, treatment with fixed orthodontic appliances can at times increase the chances of developing white spot lesions on the surfaces of teeth, thus creating a new aesthetic issue for the patient. The prevalence of white spot lesions (WSL) reported after treatment varies from 2% to 97%, and these lesions can occur despite increased attention to hygiene. Hence the aim of this study was to assess the effect of Amine fluoride mouthwash in preventing white spot lesions during fixed orthodontic therapy.

Materials and Methods

Study participants were randomly divided into two groups (Group A - experimental 25 patients and Group B - control 25 patients). The pre-intervention and post-intervention intra-oral digital photographs were analysed by using ImageJ software to assess the percentage of the facial surface affected on the teeth (10 maxillary teeth), which had white spot lesions.

Results

The mean value of WSLs showed significant difference between the experimental and control groups. Mean values of WSL in the experimental group decreased from 2 to 1.54 with a mean difference of 0.46 after 6 months of follow-up which indicated that amine fluoride mouthwash was effective in preventing WSLs during fixed orthodontic treatment.

Conclusion

WSLs scores were significantly reduced in patients who received the mouthwash when compared to patients who followed standard oral hygiene regimen with fluoridated toothpaste only. In clinical practice, amine fluoride mouthwash is an effective method for the prevention of WSLs during fixed orthodontic treatment.

Maternal methylmercury exposure during early-life periods adversely affects mature enamel structure of offspring rats at human exposure levels: a concern for oral health

Although there are many studies on the health effects of methylmercury (MeHg) toxicity during in utero and early development, little is known about its effects on mineralized tissues present in the oral cavity, such as enamel structure. Therefore, this study evaluated the effects of MeHg exposure on the physico-chemical, ultrastructural and functional properties of mature tooth enamel. Specifically, we studied offspring of mothers exposed to MeHg during the prenatal and postnatal periods which are the developmental stages associated with tooth enamel formation. Female rats were exposed to MeHg at a dose of 40 μg/kg/day for 42 days of pregnancy and lactation. The enamel of offspring was analyzed by (1) Fourier Transform Infrared Spectroscopy and Raman to assess physicochemical composition, (2) Scanning Electron Microscopy for ultrastructural evaluation, (3) Transmitted Polarizing Light Microscopy for analysis of the enamel extracellular matrix, and (4) resistance and hardness were evaluated by microhardness. The results showed that MeHg exposure during this sensitive enamel formation period induced changes in inorganic and organic content and enamel prisms ultrastructure alterations and disturbed the organic extracellular matrix due to a decreased enamel strength. These novel findings establish for the first time that maternal exposure to MeHg pre and postnatal promoted relevant changes in mature enamel of their offspring rats.

Activin receptor-like kinase 3: a critical modulator of development and function of mineralized tissues

Mineralized tissues, such as teeth and bones, pose significant challenges for repair due to their hardness, low permeability, and limited blood flow compared to soft tissues. Bone morphogenetic proteins (BMPs) have been identified as playing a crucial role in mineralized tissue formation and repair. However, the application of large amounts of exogenous BMPs may cause side effects such as inflammation. Therefore, it is necessary to identify a more precise molecular target downstream of the ligands. Activin receptor-like kinase 3 (ALK3), a key transmembrane receptor, serves as a vital gateway for the transmission of BMP signals, triggering cellular responses. Recent research has yielded new insights into the regulatory roles of ALK3 in mineralized tissues. Experimental knockout or mutation of ALK3 has been shown to result in skeletal dysmorphisms and failure of tooth formation, eruption, and orthodontic tooth movement. This review summarizes the roles of ALK3 in mineralized tissue regulation and elucidates how ALK3-mediated signaling influences the physiology and pathology of teeth and bones. Additionally, this review provides a reference for recommended basic research and potential future treatment strategies for the repair and regeneration of mineralized tissues.

Instant identification of dental white spot using K-means algorithm via laser-induced fluorescence and associated hyperspectral imaging

Dental caries (DC) is a chronic illness that affects 2 billion individuals worldwide, with 520 million of those suffering from it in their primary teeth. It is apparent that early DC detection and subsequent minimally invasive therapy are crucial clinical requirements. The first reversible clinical indication of demineralization is dental white spot (DWS) lesions. However, diagnosing DWS poses extreme challenges for practitioners. In this investigation, a customized laser-induced fluorescence system with a hyperspectral imaging (HI) camera and a non-ionization laser light supply was created for DWS localization and early DC detection. A UV laser diode source with a wavelength of 395 nm was used for light stimulation for the 10 test samples of teeth. The emitted signature of the main tooth components, including dentin, DWS, enamel, and DC, was recorded. An attempt was made to increase the system's sensitivity to the fluorescent signal by applying a logarithmic scale to the spectral signature. Moreover, further discrimination may be achieved by signal strength. We identified that the fluorescent signal's peak intensity at 771 nm works best for discriminating DWS from normal areas, or DC. For characterizing dentin, the re-emitted frequency at 500 nm has the maximum intensity. Next, we presented our imaging grouping strategy that combines visual enhancement through a moving average, MA, filtering and segmenting an image using K-means clustering (K-mc) (K = 8) for instant and precise DWS grouping for the constructed HI images at (500 nm and 771 nm). Despite the tiny structure and its DWS white appearance, our approach could successfully demarcate the DWS on the tested teeth. Dental examiners might benefit from our simple, non-invasive, non-ionizing optical diagnosis approach to help them make their first assessments and experience accurate and exact delineation of the DWS to obtain immediate and higher rates of early-stage DC detection.

In vitro comparative evaluation of physical and chemical properties of surface enamel after using APF and SDF with or without laser activation

PURPOSE

To evaluate and compare the changes in physical and chemical properties of the enamel surface after application of Silver Diamine Fluoride (SDF), Acidulated Phosphate Fluoride (APF), LASER activated SDF and LASER activated APF.

METHODS

Sample consisted of 72 freshly extracted healthy human premolar teeth, extracted for orthodontic purpose, free from caries, fracture or any anomalies. The selected samples were randomly divided into four groups (n = 18): Group 1 (SDF); Group 2 (APF); Group 3 (LASER activated SDF) and Group 4 (LASER activated APF). All samples were evaluated for values of DIAGNOdent at baseline, after demineralisation and after remineralisation. They were further divided and assessed for colour changes, surface alterations and fluoride content of surface enamel using Spectrophotometer, Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometry respectively. The statistical analysis was done using One-Way ANOVA, Tukey's HSD test, Mann-Whitney U test and Kruskal-Wallis Test.

RESULTS

Highest remineralising potential and maximum colour changes of surface enamel was exhibited by Group 3. Scanning Electron Micrographs of Group 3 and Group 4 exhibited regular globular structures of enamel whereas Group 1 and Group 2 showed irregular globular surface of the enamel at 2000× and 5000× magnification. Maximum fluoride uptake on the surface enamel was seen in Group 4 followed by Group 3.

CONCLUSION

Use of LASER activated topical fluorides helps to achieve superior caries prevention. LASER activated APF can be used as an aesthetic alternative to SDF, as LASER activated APF showed higher uptake of fluoride on the enamel surface without discoloration effect.

3,3'-Diindolylmethane (DIM): A Potential Therapeutic Agent against Cariogenic Streptococcus mutans Biofilm

Indole, a metabolite of the amino acid tryptophan, has been proven to act as a signal molecule in bacteria, acting in different aspects of biofilm formation. The oral biofilm is a type of biofilm that has consequences for human health. It is a complex, three-dimensional structure that develops on the surface of teeth via the attachment of primary microbial colonizers. Many oral infections are caused by an imbalance occurring in the microorganisms naturally found in oral biofilms and are considered major public health concerns. In this study, we test the effect of a natural bis-indole, 3,3'-Diindolylmethane (DIM), in mitigating the pathogenicity of the oral biofilm inhabiting bacterium Streptococcus mutans, a bacterium that is considered to be a principal etiological agent in dental caries. Our study found that DIM was able to attenuate S. mutans biofilm formation by 92%. Additionally, treatment with DIM lowered extracellular polymeric substance (EPS) production and decreased its durability significantly under acidic conditions. Therefore, the anti-biofilm and anti-virulence properties of DIM against S. mutans bacteria in an "oral setting" provides evidence for its usefulness in reducing biofilm formation and potentially for caries attenuation.

Recent advances on nanomaterials for antibacterial treatment of oral diseases

An imbalance of bacteria in oral environment can lead to a variety of oral diseases, such as periodontal disease, dental caries, and peri-implant inflammation. In the long term, in view of the increasing bacterial resistance, finding suitable alternatives to traditional antibacterial methods is an important research today. With the development of nanotechnology, antibacterial agents based on nanomaterials have attracted much attention in dental field due to their low cost, stable structures, excellent antibacterial properties and broad antibacterial spectrum. Multifunctional nanomaterials can break through the limitations of single therapy and have the functions of remineralization and osteogenesis on the basis of antibacterial, which has made significant progress in the long-term prevention and treatment of oral diseases. In this review, we have summarized the applications of metal and their oxides, organic and composite nanomaterials in oral field in recent five years. These nanomaterials can not only inactivate oral bacteria, but also achieve more efficient treatment and prevention of oral diseases by improving the properties of the materials themselves, enhancing the precision of targeted delivery of drugs and imparting richer functions. Finally, future challenges and untapped potential are elaborated to demonstrate the future prospects of antibacterial nanomaterials in oral field.

Micromechanical interlocking structure at the filler/resin interface for dental composites: a review

Dental resin composites (DRCs) are popular materials for repairing caries or dental defect, requiring excellent properties to cope with the complex oral environment. Filler/resin interface interaction has a significant impact on the physicochemical/biological properties and service life of DRCs. Various chemical and physical modification methods on filler/resin interface have been introduced and studied, and the physical micromechanical interlocking caused by the modification of fillers morphology and structure is a promising method. This paper firstly introduces the composition and development of DRCs, then reviews the chemical and physical modification methods of the filler/resin interface, mainly discusses the interface micromechanical interlocking structures and their enhancement mechanism for DRCs, finally give a summary on the existing problems and development potential.

Inorganic Compounds as Remineralizing Fillers in Dental Restorative Materials: Narrative Review

Secondary caries is one of the leading causes of resin-based dental restoration failure. It is initiated at the interface of an existing restoration and the restored tooth surface. It is mainly caused by an imbalance between two processes of mineral loss (demineralization) and mineral gain (remineralization). A plethora of evidence has explored incorporating several bioactive compounds into resin-based materials to prevent bacterial biofilm attachment and the onset of the disease. In this review, the most recent advances in the design of remineralizing compounds and their functionalization to different resin-based materials' formulations were overviewed. Inorganic compounds, such as nano-sized amorphous calcium phosphate (NACP), calcium fluoride (CaF₂), bioactive glass (BAG), hydroxyapatite (HA), fluorapatite (FA), and boron nitride (BN), displayed promising results concerning remineralization, and direct and indirect impact on biofilm growth. The effects of these compounds varied based on these compounds' structure, the incorporated amount or percentage, and the intended clinical application. The remineralizing effects were presented as direct effects, such as an increase in the mineral content of the dental tissue, or indirect effects, such as an increase in the pH around the material. In some of the reported investigations, inorganic remineralizing compounds were combined with other bioactive agents, such as quaternary ammonium compounds (QACs), to maximize the remineralization outcomes and the antibacterial action against the cariogenic biofilms. The reviewed literature was mainly based on laboratory studies, highlighting the need to shift more toward testing the performance of these remineralizing compounds in clinical settings.

Applications of photothermally mediated nanohybrids for white spot lesions in orthodontics

In orthodontic treatment, cariogenic bacteria in the oral cavity are the main cause of enamel white spot lesions (WSLs). Therefore, to effectively prevent and treat WSLs, it is crucial to inhibit the cariogenic bacterial activity while promoting the remineralization of demineralized tooth enamel. However, fluoride preparations commonly used for the prevention and treatment of WSLs can induce dental fluorosis if ingested in excess, and their remineralization effect is limited by the residual hydroxyapatite (HAp) content and salivary Ca²⁺ and PO₄^3- levels. In this study, we propose a strategy (CMCS/ACP@PDA) for antibacterial and remineralization of WSLs by a nanohybrid of carboxymethyl chitosan (CMCS)-stabilized amorphous calcium phosphate (ACP) loaded polydopamine nanoparticles (PDA NPs) based on biomimetic remineralization techniques and biocompatible near-infrared (NIR) photoactivation therapy. The nanohybrid utilizes the excellent photothermal conversion ability of polydopamine for antimicrobial purposes, while CMCS with its own positive and negative charges (-NH₃⁺ and -COO^-) acts as a biomimetic mineralizing agent to stabilize ACP, supplemented with abundant Ca²⁺ and PO₄^3- for remineralization of demineralized enamel. The results showed that CMCS/ACP@PDA could effectively inhibit the adhesion of cariogenic Streptococcus mutants (S. mutants) with high bactericidal rates. In addition, the remineralization of demineralized enamel by nanohybrid was more effective after 7 days of in vitro mineralization. This study provides a theoretical and experimental basis for the use of CMCS/ACP@PDA nanohybrid materials as potential materials against WSLs.

Parental influences on children's dairy products consumption: a narrative review

OBJECTIVE

To review research on the influence of parent-related factors on children's dairy products consumption.

DESIGN

A search of electronic databases and a narrative synthesis of the literature were conducted. English-language articles were included if they reported data relating to parental influences on children's consumption of dairy products and if statistical significance was reported.

SETTING

Studies were carried out in the USA (n 8) and in a range of countries across Europe (n 12) and Asia (n 5).

PARTICIPANTS

The subjects of this research were children aged between 2 and 12 years of age, from a range of geographical locations.

RESULTS

Twenty-five studies met the inclusion criteria. The studies examined children's dairy products consumption in relation to parental socio-economic status (education level and income) (n 12), home availability (n 2), home food environment (n 3), parental dairy products consumption (n 4), parent feeding practices (n 3), parents' beliefs and attitudes (n 3) and parental nutrition knowledge (n 3). Results on the association between socio-economic status and children's dairy products consumption varied; however, studies reporting a significant association generally observed a positive relationship. Fifteen studies reported children's total dairy products intake as an outcome measure, with the remaining studies reporting intake of milk or other dairy products as individual foods.

CONCLUSIONS

This review identified literature exploring a range of parental factors in relation to children's dairy products intake. However, there were limited numbers of studies published within each category of modifiable factors. Further research on the parent-related determinants of dairy products consumption in children is required in order to identify potential intervention targets in this age group.

Review: Application of chitosan and its derivatives in medical materials

Chitin is a natural polymeric polysaccharide extracted from marine crustaceans, and chitosan is obtained by removing part of the acetyl group (usually more than 60 %) in chitin's structure. Chitosan has attracted wide attention from researchers worldwide due to its good biodegradability, biocompatibility, hypoallergenic and biological activities (antibacterial, immune and antitumor activities). However, research has shown that chitosan does not melt or dissolve in water, alkaline solutions and general organic solvents, which greatly limits its application range. Therefore, researchers have carried out extensive and in-depth chemical modification of chitosan and prepared a variety of chitosan derivatives, which have expanded the application field of chitosan. Among them, the most extensive research has been conducted in the pharmaceutical field. This paper summarizes the application of chitosan and chitosan derivatives in medical materials over the past five years.

Analysis of Dental Enamel Remineralization: A Systematic Review of Technique Comparisons

The demineralization process conditions the structure of the enamel and begins with a superficial decalcification procedure that makes the enamel surface porous and gives it a chalky appearance. White spot lesions (WSLs) are the first clinical sign that can be appreciated before caries evolves into cavitated lesions. The years of research have led to the testing of several remineralization techniques. This study's objective is to investigate and assess the various methods for remineralizing enamel. The dental enamel remineralization techniques have been evaluated. A literature search on PubMed, Scopus, and Web of Science was performed. After screening, identification, and eligibility processes 17 papers were selected for the qualitative analysis. This systematic review identified several materials that, whether used singly or in combination, can be effective in the process of remineralizing enamel. All methods have a potential for remineralization when they come into contact with tooth enamel surfaces that have early-stage caries (white spot lesions). From the studies conducted in the test, all of the substances used to which fluoride has been added contribute to remineralization. It is believed that by developing and researching new remineralization techniques, this process might develop even more successfully.

Recent advances in the use of inorganic nanomaterials as anti caries agents

Caries is the most prevalent and widespread chronic oral disease. Traditional caries filling materials, due to their lack of anti-caries capabilities, can readily develop secondary caries. Nanomaterials proposed as an effective approach for caries treatment can inhibit biofilm formation. It also can not only reduce demineralization but also promote remineralization. In recent years, nanotechnology in anti-caries materials, particularly nano-adhesive and nano-composite resin, has advanced rapidly. Because inorganic nanoparticles (NPs) interfere with bacterial metabolism and inhibit biofilm development, inorganic NPs have emerged as a new trend in dental applications. Metal and metal oxide NPs by releasing metal ions, oxidative stress induction, and non-oxidative mechanisms showed significant antimicrobial activity. For applying metal and metal oxide NPs as anti caries agents, silver, zinc, titanium, copper, and calcium ions have been shown significant attention. Moreover, fluoride functionalized inorganic NPs were also employed to improve their efficacy of them. The fluoride-functionalized NPs can promote remineralization, and inhibit demineralization by enhancing apatite formation. In this review, we have provided an overview and recent advances in the use of inorganic NPs as anti caries agents. Furthermore, their antimicrobial, remineralizing, and mechanical impacts on dental materials were discussed.

Enamel Remineralization and Crystallization after Fluoride Iontophoresis

Early caries lesions consist of noncavitated subsurface demineralization caused by the dissolution of hydroxyapatite from the surface to the subsurface area of the enamel. Such lesions cannot be remineralized effectively by the conventional treatment. Thus, there is a need for a noninvasive technique capable of delivering the remineralizing agent to subsurface sites. For this purpose, fluoride iontophoresis (IP) using weak currents has been investigated with some conflicting results and no information on the crystal structure and composition. Because enamel remineralization involves the role of fluid from dentin, the presence of enamel fluid is necessary to determine the repair associated with the physiological condition. This study aimed to investigate structural and compositional characteristics, including the remineralizing effect of 5% sodium fluoride (NaF) IP with different polarities, cathodal iontophoresis (CIP), and anodal iontophoresis (AIP) for the treatment of natural enamel caries under simulated pulpal pressure. A bulk measurement of the crystal structure inside the lesion was first determined using calcium (Ca) K-edge X-ray absorption spectroscopy. IP with both polarities significantly promoted subsurface remineralization. The CIP generated a significant increase in the Ca/phosphorus ratio, and fluoride at the surface lesion significantly correlated with higher mineral density (MD) and more strengthening crystal structure of the lesion volume, while the lesion's MD and other impurities at the lesion surface, mostly the carbonate ions, affected the significant increase in MD with the unchanged structure of the lesion volume after AIP. The CIP of NaF is an ideal method for rapid enamel remineralization and recrystallization of fluoroapatite/fluorohydroxyapatite.

Evaluation of the clinical impact and In Vitro antibacterial activities of two bioactive restoratives against S. mutans ATCC 25175 in class II carious restorations

Background

Streptococcus mutans is a Gram-positive opportunistic bacterial pathogen and that causes dental caries and then restorative treatment remains the best clinical practice approach to repair and prevent dental caries.

Aims

This study compared the antimicrobial performance of resin modified glass ionomer cement (RM-GIC) and ACTIVA restoratives by evaluating the S. mutans count, pH levels, and plaque index (PI) scores before and on the 7^th day of restoration, and then determined the antimicrobial activities against S. mutans ATCC 25175 in both restoratives in vitro.

Materials and Methods

Seventy-eight eligible Saudi female participants, with class II carious lesions, were randomly distributed into RM-GIC and ACTIVA restorative groups. We evaluated the S. mutans count by the serial dilution technique and salivary pH by using a portable pH meter. The PI scores were determined by Silness-Löe method and the antibacterial activity by the agar well diffusion method. Statistical analysis of normality distribution was performed with the Kolmogorov-Smirnov and the difference between groups was an analysis by paired t-test. In addition, the independent sample was compared with the independent samples t-test.

Results

Both groups reduced the S. mutans count, pH acidity, and PI scores, and this reduction was statistically significant on the 7^th day of restoration (P < 0.05), preference for ACTIVA. The in vitro antibacterial activity against S. mutans ATCC 25175 showed a non-significant difference between both bioactive restorative materials (P < 0.05).

Conclusion

The novel application of ACTIVA restorative material is a promising option for patients at risk of caries.

Remineralization Potential of Three Restorative Glass Ionomer Cements: An In Vitro Study

The aim of this in vitro study was to evaluate the remineralizing ability of three glass ionomers on demineralized dentin with different thicknesses and time periods. Fifty third molars were obtained and were sectioned into 1-, 2-, and 3-mm thick slices (n = 36 for each thickness). The specimens were demineralized with 18% EDTA for 2 h. From the glass ionomer cements (GICs) under study (Ketac Molar Aplicap, Equia Forte, or Riva Light Cure), 1 mm was placed over each slice, set, and preserved in PBS until observation after 1, 7, 14, and 28 days after placement. For each material, thickness, and time, three samples were prepared. Using Fourier Transform Infrared Spectrometry (FTIR), apatite formation was determined on the side opposite to that on which the material had been placed. By means of Energy Dispersive Spectroscopy (EDX), the changes in the Calcium/Phosphate (Ca/P) ratio were evaluated. These changes were compared between the different materials by means of a two-way ANOVA test, considering time and dentin thickness, for a significance level of p < 0.05. Results: FTIR showed a peak at 1420 cm^-1, evidencing the presence of carbonated hydroxyapatite in all the materials after 14 days, which indicates that a remineralization process occurred. Riva Light Cure showed the most homogeneous results at all depths at 28 days. The Ca/P ratio was maximum at 7 days in 2 mm of dentin for Riva Light Cure and Equia Forte HT (3.16 and 3.07; respectively) and for Ketac Molar at 14 days in 1 mm (3.67). All materials induced remineralization. Equia Forte achieved the greatest effect at 2 mm and Ketac Molar at 1 mm, whereas Riva Light Cure showed similar results at all depths. In terms of Ca/P ratio, Equia Forte and Riva Light Cure remineralized best at 2 mm, whereas for Ketac Molar, it was 1 mm. Carbonate apatite formation was higher at 24 h and 7 days for Ketac Molar, whereas it decreased at 14 days for Ketac Molar and peaked in Riva Light Cure and Equia Forte.

Impact of Dairy Products and Plant-Based Alternatives on Dental Health: Food Matrix Effects

The impact of dairy products on dental health has been researched widely and shows an important role of various constituents, as well as the specific product matrix, in maintaining and improving dental health. These include, for instance, the position of lactose as the least cariogenic fermentable sugar, the high levels of calcium and phosphate, the presence of phosphopeptides as well as the antibacterial peptides lactoferrin and lysozyme and high buffering capacity. With plant-based alternatives for dairy products being developed and marketed these days, the specific benefits of dairy products in relation to dental health are often overlooked and most products contain more cariogenic carbohydrates, lack phosphopeptides, and have fewer minerals and less buffering capacity. Comparative studies performed to date indeed suggest that plant-based products do not match dairy counterparts when it comes to maintaining and improving dental health. Careful consideration of these aspects is required in relation to future developments of products and human diets. In this paper, we review the impact of dairy products and plant-based dairy alternatives on dental health.

Chemical, structural and cytotoxicity characterisation of experimental fluoride-doped calcium phosphates as promising remineralising materials for dental applications

OBJECTIVES

This study aimed at evaluating the cytotoxicity, chemical and structural properties of experimental fluoride-doped calcium-phosphates as potential remineralising materials for dental applications.

METHODS

Experimental calcium phosphates were formulated using β-tricalcium phosphate, monocalcium phosphate monohydrate, calcium hydroxide, and different concentrations of calcium/sodium fluoride salts [(5 wt%: VSG5F), (10 wt%: VSG10F), (20 wt%: VSG20F)]. A fluoride-free calcium phosphate (VSG) was used as control. Each tested material was immersed in simulated body fluid (SBF), (24 h, 15 and 30 days) to assess their ability to crystallise into apatite-like. Cumulative fluoride release was assayed up to 45 days. Moreover, each powder was placed into a medium containing human dental pulp stem cells (200 mg/mL) and their cytotoxicity was analysed using the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay (24 h, 48 h and 72 h incubation). These latter results were statistically analysed by ANOVA and Tukey's test (α = 0.05).

RESULTS

All the experimental VSG-F materials produced fluoride-containing apatite-like crystals after SBF immersion. VSG20F presented prolonged release of fluoride ions into the storage media (45d). VSG, VSG10F and VSG20F showed a significant cytotoxicity at dilution of 1:1, while at 1:5, only VSG and VSG20F demonstrated a reduction in cell viability. At lower dilutions (1:10, 1:50 and 1:100) all specimens showed no significant toxicity to hDPSCs, but an increase in cell proliferation.

SIGNIFICANCE

The experimental fluoride-doped calcium-phosphates are biocompatible and possess a clear ability to evoke fluoride-containing apatite-like crystallisation. Hence, they may be promising remineralising materials for dental applications.

Radiological and Histological Analyses of Nonrigid Versus Rigid Fixation for Free Bone Block Procedures in a Rabbit Model of Glenoid Defects

BACKGROUND

Nonrigid fixation techniques have been recently introduced in free bone block (FBB) procedures to treat substantial glenoid bone loss in patients with anterior shoulder instability. However, the radiological and histological effectiveness of nonrigid fixation versus conventional rigid fixation have not been comprehensively understood in vivo.

PURPOSE

To (1) explore the radiological and histological characteristics of nonrigid fixation for FBB procedures in a rabbit model of glenoid defects and (2) further compare them with those of conventional rigid fixation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Unilateral shoulder glenoid defects were created in 36 mature New Zealand White rabbits, of which 24 underwent FBB procedures using allogenic iliac crest bone and were randomly divided into rigid fixation (RF) and nonrigid fixation (N-RF) groups, with the remaining divided into 2 control groups: 6 with sham surgery for glenoid defects (GD group) and 6 native glenoids (normal group). In the RF and N-RF groups, 6 rabbits were sacrificed at 6 or 12 weeks postoperatively for radiological and histological analyses of the reconstructed glenoid, and all rabbits in the GD and normal groups were sacrificed at 12 weeks. The radiological glenoid morphology was evaluated via micro-computed tomography. Moreover, the graft-glenoid healing and graft remodeling processes were determined using histological staining.

RESULTS

At 6 weeks, both the N-RF and RF groups had similarly improved radiological axial radian and en face area of the glenoid compared with the GD group, but the N-RF group showed superiority in restoration of the glenoid radian and area compared with the RF group at 12 weeks, with the native glenoid as the baseline. Histologically, the bone graft in both groups was substantively integrated into the deficient glenoid neck at 6 and 12 weeks, showing similar osseous healing processes at the graft-glenoid junction. Moreover, the bone graft histologically presented similar regenerated vascular density, total graft bone, and integrated graft bone in both groups. In contrast, the N-RF group had a different remodeling profile on radiological and histological analyses regarding regional bone resorption, mineralization, and fibrous tissue replacement during osseointegration.

CONCLUSION

Compared with rigid fixation, nonrigid fixation resulted in superior reconstructed glenoid morphology radiologically and similar graft-glenoid osseous healing histologically, showing different graft remodeling profiles of regional bone resorption, mineralization, and fibrous tissue replacement.

CLINICAL RELEVANCE

The nonrigid fixation technique can be feasible for FBB procedures to treat glenoid bone loss in anterior shoulder instability. More clinical evidence is required to determine its pros and cons compared with conventional rigid fixation.

A novel rapidly mineralized biphasic calcium phosphate with high acid-resistance stability for long-term treatment of dentin hypersensitivity

OBJECTIVES

Treating dental hypersensitivity (DH) rapidly and maintaining long-term effectiveness remains challenging. We aimed to address this problem by fabricating a novel rapidly mineralized biphasic calcium phosphate (RMBCP), which could rapidly elicit mineralization to form hydroxyapatite (HA) and perform excellent acid-resistant stability, thus effectively blocking the exposed dental tubules and protecting them from acid attack.

METHODS

RMBCP was firstly synthesized by precisely adjusting the molar ratio of acetic acid and calcium hydroxide and characterized by X-ray diffraction (XRD), X-ray fluorescence microprobe (XRF), Fourier-transform infrared (FTIR) spectrometer, scanning electron microscope (SEM), and transmission electron microscope (TEM). Subsequently, using a commercialized desensitizing agent, 45S5 bioglass (BG), as the control group, the mineralization performance of RMBCP was investigated in simulated body fluid (SBF), Dulbecco's modified eagle medium (DMEM), and even slightly acidic artificial saliva (pH=6.6). Moreover, the biocompatibility of RMBCP was studied. Finally, the tubule occlusion effect and acid-resistant stability of RMBCP were evaluated in vitro and in vivo.

RESULTS

The rapid mineralization behavior of RMBCP could easily adhere to the dentin surface and block the dentinal tubules completely in vitro and in vivo within 7days. RMBCP performed high acid-resistant stability to maintain the long-term therapeutic effect of DH treatment.

SIGNIFICANCE

Developing novel bioactive calcium phosphate materials with the ability to trigger mineralization for HA formation rapidly will be an effective strategy for the long-term treatment of dentin hypersensitivity.

Multifunctional dental resin composite with antibacterial and remineralization properties containing nMgO-BAG

The inherent characteristics of resin composite can lead to micro-leakage after polymerization shrinkage. The bacteria invasion through edge micro-leakage and attachment onto the material surface can cause secondary caries, reducing the service life of resin composites. In this study, magnesium oxide nanoparticles (nMgO) as an inorganic antimicrobial agent and bioactive glass (BAG) as a remineralization agent were simultaneously incorporated into the resin composite. With the addition of both nMgO and BAG, the resin composite showed an excellent antimicrobial effect compared to the resin composite with nMgO or BAG only. The remineralization capacity of demineralized dentin increased with the increasing content of BAG. Vickers hardness, compressive strength, and flexural strength of the resin composite with nMgO-BAG were not significantly affected compared to the ones with the same total filler amount but with BAG only. The depth of cure and water sorption values of the resin composite showed an increasing trend with the increasing total amount of nMgO and BAG fillers. This developed multifunctional resin composite is expected to reduce bacterial invasion and promote remineralization of early caries damage.

White Spot Lesions (WSLs)-Post-Orthodontic Occurrence, Management and Treatment Alternatives: A Narrative Review

Although treatment with fixed or mobile appliances has become an important part of modern orthodontics, side effects such as white spot lesions (WSLs) have a negative impact on the aesthetic outcome of orthodontic treatment. The purpose of this article was to review current evidence on the diagnosis, risk assessment, prevention, management and post-orthodontic treatment of these lesions. Data collection was performed electronically, and the initial search using the keywords "white spot lesions", "orthodontics", "WSL", "enamel" and "demineralization" in different combinations resulted in 1032 articles for the two electronic databases used. Ultimately, a total of 47 manuscripts were considered relevant to the aim of this research and included in this review. The results of the review indicate that WSLs remain a significant problem during orthodontic treatment. According to studies in the literature, the severity of WSLs correlates to the duration of treatment. Using toothpaste with more than 1000 ppm fluoride at home reduces the frequency of WSL separation and regular application of varnishes in the office reduces the frequency of the occurrence of WSLs only in the context of maintaining a strict hygiene regime. The old hypothesis that elastomeric ligatures retain more dental plaque than metal ones has been refuted. There are no differences in the appearance of WSLs between conventional brackets and self-ligating brackets. Clear aligner mobile devices develop fewer WSLs but are more extensive as opposed to conventional fixed devices, while lingual orthodontic appliances have a lower incidence of WSLs, and the most effective device for preventing these lesions is WIN, followed by Incognito.

Biomimetic Action of Zinc Hydroxyapatite on Remineralization of Enamel and Dentin: A Review

Biomimetic zinc-carbonate hydroxyapatite technology was developed to realize materials that mimic the natural hydroxyapatite of enamel and dentin and possess good activity in terms of affinity to adhere to these biological tissues. The chemical and physical characteristics of this active ingredient allows the hydroxyapatite itself to be particularly similar to dental hydroxyapatite, enhancing the bond between biomimetic hydroxyapatite and dental hydroxyapatite. The aim of this review is to assess the efficacy of this technology in terms of benefits for enamel and dentin and reduction of dental hypersensitivity.

MATERIALS AND METHODS

A literature search (Pubmed/MEDLINE and Scopus) of articles from 2003 to 2023 was conducted to analyze studies focused on the use of zinc-hydroxyapatite products. Duplicates were eliminated from the 5065 articles found, leaving 2076 articles. Of these, 30 articles were analyzed based on the use of products with zinc-carbonate hydroxyapatite in these studies.

RESULTS

30 articles were included. Most of the studies showed benefits in terms of remineralization and prevention of enamel demineralization in terms of occlusion of the dentinal tubules and reduction of dentinal hypersensitivity.

CONCLUSION

Oral care products such as toothpaste and mouthwash with biomimetic zinc-carbonate hydroxyapatite were shown to provide benefits according to the aims of this review.

Effect of Different Mouthwashes on the Surface Microhardness and Color Stability of Dental Nanohybrid Resin Composite

BACKGROUND

Surface microhardness and color stability of dental restorative material should be sustained throughout its functional lifetime to maintain the esthetic quality of the restoration. However, the frequent application of mouthwash may affect their surface microhardness and color stability. The aim of this study was to evaluate the effects of different types of mouthwashes with different contents on surface microhardness and color stability of dental nanohybrid resin-based composite.

METHODS

Disc specimens of nanohybrid resin composite (Luna Nano-Hybrid Composite) were prepared according to manufacturing instructions; specimens were incubated for 24 h in three types of mouthwash (Chlorohexidine, Listerine Green Tea, and Colgate Optic White Whitening Mouthwash). Artificial saliva was used as a control group. Surface microhardness was evaluated using Vickers microhardness device. Color stability after and before immersion in the different mouthwashes was evaluated using extra-oral spectrophotometer; the values of color change (ΔE₀₀) were subsequently calculated. Data were analyzed using one-way ANOVA and post hoc test (p ≤ 0.05).

RESULTS

There was no significant difference between microhardness of resin composite immersed in artificial saliva, CHX, and Green Tea mouthwashes (78.5, 78.4, and 73.5, respectively) (p ≥ 0.1), while the bleaching mouthwash led to the lowest microhardness of resin composite, with significant difference compared to the three previous immersion media (p = 0.002). Moreover, there were significant differences in the color changes (ΔE₀₀) of resin composite exposed to the various immersion media (p = 0.0001).

CONCLUSIONS

The bleaching mouthwash led to a significant reduction in nanohybrid resin composite's microhardness compared to the chlorohexidine and Green Tea containing mouthwashes. The resin composite's color change was accepted in bleaching mouthwash but unaccepted in chlorohexidine and Green Tea containing mouthwashes.

Red Marine Algae Lithothamnion calcareum Supports Dental Enamel Mineralization

The current management of oral conditions such as dental caries and erosion mostly relies on fluoride-based formulations. Herein, we proposed the use of the remaining skeleton of Lithothamnion calcareum (LC) as an alternative to fluorides. LC is a red macroalgae of the Corallinales order, occurring in the northeast coast of Brazil, whose unique feature is the abundant presence of calcium carbonates in its cell walls. Two experimental approaches tested the general hypothesis that LC could mediate enamel de-remineralization dynamics as efficiently as fluorides. Firstly, the effect of LC on enamel de-mineralization was determined in vitro by microhardness and gravimetric measurements to test the hypothesis that LC could either prevent calcium/phosphate release from intact enamel or facilitate calcium/phosphate reprecipitation on an artificially demineralized enamel surface. Subsequently, an in situ/ex vivo co-twin control study measured the effect of LC on the remineralization of chemical-demineralized enamel using microhardness and quantitative light-induced fluorescence. With this second experiment, we wanted to test whether outcomes obtained in experiment 1 would be confirmed by an in situ/ex vivo co-twin control model. Both experiments showed that LC exhibited equivalent or superior ability to modulate enamel de-remineralization when compared to fluoride solution. LC should be explored as an alternative to manage oral conditions involving the enamel demineralization.

The Localized Ionic Microenvironment in Bone Modelling/Remodelling: A Potential Guide for the Design of Biomaterials for Bone Tissue Engineering

Bone is capable of adjusting size, shape, and quality to maintain its strength, toughness, and stiffness and to meet different needs of the body through continuous remodeling. The balance of bone homeostasis is orchestrated by interactions among different types of cells (mainly osteoblasts and osteoclasts), extracellular matrix, the surrounding biological milieus, and waste products from cell metabolisms. Inorganic ions liberated into the localized microenvironment during bone matrix degradation not only form apatite crystals as components or enter blood circulation to meet other bodily needs but also alter cellular activities as molecular modulators. The osteoinductive potential of inorganic motifs of bone has been gradually understood since the last century. Still, few have considered the naturally generated ionic microenvironment's biological roles in bone remodeling. It is believed that a better understanding of the naturally balanced ionic microenvironment during bone remodeling can facilitate future biomaterial design for bone tissue engineering in terms of the modulatory roles of the ionic environment in the regenerative process.

Porous phosphate-based bioactive glass /β-TCP scaffold for tooth remineralization

The total or partial loss of teeth in the Mexican population due to periodontal diseases and trauma causes the development of other conditions, such as limitations in chewing and grinding food, pronunciation difficulties, and oral aesthetic alterations. In Mexico, oral diseases have been described to affect 87% of the population, according to reports by the health services, emphasizing that pregnant women and patients with diabetes mellitus have the highest risk of presenting with severe periodontal diseases or tooth loss, according to findings by the Mexican Health Department's Specific Action Program for the prevention, detection, and control of oral health problems (2013-2018). There was a 92.6% prevalence of dental caries in the population examined, and the prevalence of periodontal problems, mainly in 40-year-olds, was above 95%. The objective of this investigation was to manufacture and characterize porous 3D scaffolds with innovative chemical compositions, using phosphate-based bioactive glass, beta-phase tricalcium phosphate, and zirconium oxide, in variable quantities. The scaffold manufacturing method combined two techniques: powder metallurgy and polymer foaming. The results obtained in this research were promising since the mechanically tested scaffolds showed values of compressive strength and modulus of elasticity in the range of human trabecular bone. On the other hand, the in vitro evaluation of the samples immersed in artificial saliva at days 7 and 14 presented the calcium/phosphorus ratio = 1.6; this value is identical to the reported state-of-the-art figure, corresponding to the mineral phase of the bones and teeth. Likewise, the precipitation of the flower-like morphology was observed on the entire surface of the scaffold without zirconia; this morphology is characteristic of hydroxyapatite. On the other hand, the samples with 0.5 and 1.0 mol% zirconia showed less hydroxyapatite formation, with a direct correlation between scaffold dissolution and the amount of zirconia added.

Effect of fluoride varnish in combination with simulated oral environment on enamel-bracket shear bond strength

To determine the effect of fluoride varnish application combined with a simulated oral environment prior to bracket bonding on the shear bond strength (SBS) between brackets and tooth enamel. Sixty de-identified, extracted teeth were grouped to either receive or not receive fluoride varnish and then stored for 7 days at 37 °C in phosphate-buffered saline (PBS) solution or PBS combined with three 15-min cycles/day in a demineralizing solution to simulate pH variation following meals. Subsequently, brackets were bonded and after 24-h dark cure at 37 °C, debonded using shear forces in a simulated oral environment. The maximum shear force was used to calculate SBS, and the adhesive remnant index (ARI) was determined by image analysis of photos of the bracket mesh pad after debonding. A statistically higher SBS (10.16 MPa) was observed when fluoride varnish was applied prior to storage in PBS + demineralizing solution compared to SBS (6.38 MPa) following storage in the same solution without varnish application. Based on 37% effect size, this difference is also clinically relevant. In contrast, no significant differences in SBS were observed with varnish application combined with PBS with no demineralizing solution or between storage solution alone. Moreover, there was no significant difference in ARI due to varnish combined with either storage method or storage solution only. Results suggest varnish application prior to bracket bonding in combination with simulated oral environment that included acid exposure is beneficial in maintaining higher SBS between bracket and enamel. Despite higher SBS, adhesive remaining on enamel did not increase.

Effects of an orthodontic primer containing amorphous fluorinated calcium phosphate nanoparticles on enamel white spot lesions

OBJECTIVES

The study investigated the effects of an orthodontic primer containing amorphous fluorinated calcium phosphate (AFCP) nanoparticles on enamel white spot lesions (WSLs).

MATERIALS AND METHODS

The AFCP nanoparticles were prepared and incorporated into Transbond XT Primer. Thirty-two human enamel slices were highly polished and randomly divided into four groups: no part covered (control), half covered with a primer containing 0 wt%, 25 wt%, and 35 wt% AFCP. Subsequently, samples were challenged by a modified pH-cycling and characterized by color measurement, micro-computed tomography, and scanning electron microscope (SEM). The bonding properties of the primers containing AFCP were assessed using shear bond strength test, and the mouse fibroblasts (L929) were employed to evaluate the cytotoxicity.

RESULTS

When the enamel was challenged by pH cycling, 25 wt% and 35 wt% AFCP groups exhibited less color change (ΔE) and less mineral loss than the control and 0 wt% AFCP groups. The SEM images showed that the original microstructural integrity and mineral deposition rate of the enamel surface were better in the 25 wt% and 35 wt% AFCP groups. In particular, the 35 wt% AFCP group exhibited the best performance after 3 weeks of pH cycling. The shear bond strength and cell viability revealed no significant difference among the tested groups (P > 0.05).

CONCLUSION

Using the primer containing 35 wt% AFCP might be a promising strategy for preventing the occurrence and development of WSLs during orthodontic treatment.

Polyphenols Can Improve Resin-Dentin Bond Durability by Promoting Amorphous Calcium Phosphate Nanoparticles to Backfill the Dentin Matrix

Objective

To investigate the effects of proanthocyanidins (PA), myricetin, resveratrol, and kaempferol on the modification of dentin collagen and the inhibition of matrix metalloproteinase (MMP) activity, and to evaluate their contributions to the biomimetic remineralization and resin-dentin bonding performance.

Methods

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and in situ zymography were applied to verify the collagen modification and MMP activity inhibition induced by these four polyphenols. Scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) analysis, X-ray diffraction (XRD), ATR-FTIR, Vickers hardness numbers (VHN), and micro-computed tomography (micro-CT) were performed to characterize the remineralized dentin. Microtensile bond strength (μTBS) and nanoleakage were investigated to evaluate the effects of the four polyphenols on resin-dentin bonding durability.

Results

ATR-FTIR and in situ zymography confirmed that these four polyphenols could modify dentin collagen and inhibit MMP activity, respectively. Chemoanalytic characterization exhibited the efficacies of the four polyphenols in promoting dentin biomimetic remineralization. The surface hardness of PA-pretreated dentin was the greatest. Micro-CT results demonstrated that the PAs group possessed the highest amount of dentin surface minerals and the lowest amount of deep-layer minerals. The surface and deep-layer mineral contents of the Myr group were higher than Res and Kae groups. Treatment with these four polyphenols significantly increased the initial μTBS compared with the control group without primer conditioning. μTBS decreased significantly during aging, and the decrease was more severe in the PAs and Kae groups than in the Myr and Res groups. With or without aging, the polyphenol groups exhibited relatively less fluorescence. However, the Myr and Res groups showed less serious nanoleakage after aging.

Conclusion

PA, myricetin, resveratrol, and kaempferol can modify dentin collagen, inhibit MMP activity, promote biomimetic remineralization, and improve resin-dentin bond durability. Compared with PA and kaempferol, myricetin and resveratrol are more effective in improving resin-dentin bonding.

Inhibition of tooth demineralization caused by Streptococcus mutans biofilm via antimicrobial treatment using hydrogen peroxide photolysis

OBJECTIVES

An antimicrobial technique utilizing hydroxyl radicals generated by the photolysis of 3% H₂O₂ has been developed recently. The present study aimed to evaluate the effect of H₂O₂ photolysis treatment on tooth demineralization caused by Streptococcus mutans biofilm.

MATERIALS AND METHODS

To induce tooth demineralization, S. mutans biofilm was allowed to form on the maxillary first molars collected from Wistar rats via 24-h culturing. The samples were immersed in 3% H₂O₂ and irradiated with 365-nm LED (H₂O₂ photolysis treatment). Viable bacterial counts in the biofilm were evaluated immediately after treatment and after an additional 30-h culturing by colony counting. The acidogenicity of the biofilm, re-established 30 h after treatment, was assessed by measuring the pH. The effect of H₂O₂ photolysis treatment on tooth demineralization was assessed by measuring the depth of the radiolucent layer in micro-CT images.

RESULTS

H₂O₂ photolysis significantly reduced viable bacterial counts in the biofilm to 3.7 log colony forming units (CFU)/sample, while the untreated group had 7.9 log CFU/sample. The pH of the biofilm re-established after treatment (6.6) was higher than that of the untreated group (5.3). In line with the pH measurement, the treatment group had a significantly lower depth of radiolucent layer in dentin than the untreated group.

CONCLUSIONS

H₂O₂ photolysis treatment was effective not only in killing the biofilm-forming S. mutans but also in lowering the acidogenicity of the biofilm. Thus, this technique could inhibit tooth demineralization.

CLINICAL RELEVANCE

H₂O₂ photolysis can be applicable as a new dental caries treatment.

Synbiotic-fluoride synergism on enamel remineralization, cytotoxicity and genotoxicity

OBJECTIVE(S)

The objectives of the present study were to examine the - a) enamel remineralization potential of synbiotic-fluoride (SF) therapy using a multi-species bacterial pH-cycling model; and b) cytotoxic and genotoxic effects of SF therapy extracts.

MATERIALS AND METHODS

The SF therapy group comprised of 2% arginine (Arg), 0.2% NaF, and a probiotic Lactobacillus rhamnosus GG (LRG). The intervention groups studied were: 1) No treatment; 2) 2% Arg; 3) 0.2% NaF; 4) LRG; 5) 2% Arg+0.2% NaF; 6) 2% Arg+LRG; 7) 0.2% NaF+LRG; and 8) 2% Arg+0.2% NaF+LRG (SF therapy). The enamel remineralization potential of SF therapy was investigated under cariogenic biofilm challenge; while the cytotoxicity and genotoxicity of SF therapy extracts were examined on HGF-1 and Chinese hamster fibroblast V79, respectively. To determine the remineralization effect, the specimens were subjected to mineral density (MD) assessment using micro-CT, Ca/P molar ratio with SEM-EDX, and enamel fluoride uptake (EFU) estimates. The HGF-1 proliferation assessment was quantified using MTT/CCK-8 assays with qualitative analysis by nuclei staining Hoechst-based fluorescence imaging. The genotoxicity was determined by micronuclei formation test.

RESULTS

Mineral gain and %remineralization derived from MD assessment for the SF therapy were significantly higher than the other groups (p<0.05). The %ΔCa/P for the SF and 2% Arg+0.2% NaF were significantly higher than the other groups (p<0.05). The SF and 2% Arg+0.2% NaF groups had the highest EFU compared to the other groups (p<0.05). No significant difference in the %viable HGF-1 cells were observed between the treatment interventions and no treatment group (p>0.05). Compared to the EMS-positive control, the micronuclei formation for all the intervention groups was significantly lower (p<0.05), with no significant difference among the treatment groups (p>0.05).

CONCLUSION

The SF therapy enhanced enamel remineralization with no biocompatibility concerns.

CLINICAL SIGNIFICANCE

With the enhanced enamel remineralization potential discerned in the present study, the SF therapy can be used as a promising caries-preventive agent targeted for high caries-risk individuals.

Remineralization Potential of a Combination of Chitosan with Nanohydroxyapatite and a Self-assembling Peptide with Nanohydroxyapatite: An In Vitro Study

AIM

This study explores the demineralizing potential of the combination of chitosan with nanohydroxyapatite (n-HA) and self-assembling peptides with n-HA.

MATERIALS AND METHODS

A total of 66 first premolar teeth of similar dimensions extracted for orthodontic purposes were collected for this study. These were then demineralized and randomly divided into the following three groups (n = 22): (i) Control group, (ii) n-HA + Chitosan (HAC), and (iii) self-assembling peptide + n-HA (SP-HA). The samples in each group were brushed every 24 hours with the respective agent. The specimens were stored in Fusayama Meyer's artificial saliva at room temperature and the solution was replenished daily. Mineral content (Ca, P) and surface morphology of the specimens was analyzed, using scanning electron microscopy and energy dispersion X-ray spectroscopy (SEM-EDAX), before demineralization, at 15 days of remineralization and 30 days of remineralization. A two-way analysis of variance (ANOVA) test followed by Tukey's honest significant difference (HSD) post hoc analysis was used to compare the mean elemental composition of the different groups (p < 0.05).

RESULTS

There was no significant difference in the calcium (Ca) and phosphate (P) weight percentage between the different groups at the baseline and after demineralization. The Ca and P weight percentages of all three groups after remineralization for 15 and 30 days showed no significant difference from the baseline or after demineralization. The surface morphology after 15 days of remineralization therapy showed decreased surface porosity and increased mineral deposition in the HAC group than the HP-SA group. Surface morphology after 30 days of remineralization showed a more homogenous and smoother surface in the HAC group than the HP-SA group.

CONCLUSION

From the results of this study, it can be concluded that the combination of chitosan with n-HA and self-assembling peptides with n-HA can be considered effective demineralizing agents.

CLINICAL SIGNIFICANCE

Considering the non-invasive nature of remineralization therapy understanding the effectiveness of different agents is of utmost importance. The demineralizing properties of chitosan, n-HA and self-assembling peptides make their combinations ideal for studying their effectiveness in treating white spot lesions.