The use of hydroxyapatite toothpaste to prevent dental caries

Color Masking Ability of Guided Enamel Regeneration with a Novel Self-Assembling Peptide and Resin Infiltration on Artificial Enamel Lesions Under Various Challenges: An In Vitro Spectrophotometric Analysis

The color masking ability of resin infiltration (RI) and curodont repair fluoride plus-self-assembling peptide (CRFP-SAP) was investigated under various simulated oral challenging conditions. Sixty-four extracted caries-free human canines were randomly divided into two groups: Group 1 (RI) and Group 2 (CRFP-SAP). The baseline color values of samples were recorded using a spectrophotometer (VITA Easyshade® Advance 4.0 VITA Zahnfabrik, Bad Sackingen, Germany). The samples were stored in a demineralization solution for 4 days to induce artificial enamel lesions (AELs). The AELs of Groups I and II were treated with RI (Icon, DMG, Hamburg, Germany) and CRFP-SAP (vVARDIS, Zug, Switzerland), respectively, followed by color measurements. Each group was subjected to challenges such as remineralization, pH cycling, staining, and thermocycling, followed by color measurements. The difference between the mean ∆E (color difference value) of sound enamel and both treatment groups was less than 3.7 1-week post treatment. Meanwhile, the difference between the mean ∆E of RI-treated samples and all kinds of challenges was more than 3.7, while for the CRFP-SAP-treated samples, it was less than 3.7 for all kinds of challenges, except for the thermocycling, for which the mean ∆E difference was 4.3. RI and CRFP-SAP treatments were effective in masking the discoloration caused by AELs. However, the color was not stable for RI-treated samples, whereas it was stable for CRFP-SAP-treated samples under all challenges, except for thermocycling.

Preparation of CMC/ACP/PHMB nanocomposites and preliminary study on their antibacterial and remineralization functions

Caries is a chronic oral disease causing a series of complications. This study aims to develop a material that could remineralize demineralized enamel and simultaneously exert antibacterial effects. A carboxymethyl chitosan (CMC)/amorphous calcium phosphate (ACP)/polyhexamethylene biguanide hydrochloride (PHMB) nanocomposite was synthesized for the first time, and its stability, remineralization ability, and antibacterial properties were investigated in this study. PHMB has excellent antibacterial properties, was used as an additive to stabilize ACP. The enamel surface covered with CMC/ACP/PHMB showed a uniform layer with a similar elemental ratio to that of natural hydroxyapatite and the ratio of crystal diffraction peaks was close to that of natural enamel. The mechanical properties, including hardness and elastic modulus, of the enamel in all experimental groups were restored. The antibacterial effect of 240 mg/L CMC/ACP/PHMB was comparable to that of 0.12% CMC/ACP/chlorhexidine. This study provides a theoretical and experimental basis for the development of novel dual-function anticaries agent.

Clinical evidence of caries prevention by hydroxyapatite: An updated systematic review and meta-analysis

OBJECTIVES

A systematic review and meta-analysis were undertaken to update our 3-year-old meta-analysis to include RCTs, in vivo, and in situ clinical evidence that showed hydroxyapatite in oral care products can reduce dental caries.

DATA

Using the PICO guide, published clinical trials were searched where subjects (P) of all ages, with primary, mixed or permanent dentitions, using toothpastes, mouthwashes or gels containing hydroxyapatite as an active ingredient (I) were compared to subjects who used placebo or no intervention, or fluoride-containing positive controls (C), and the outcomes (O) were direct measurement of reduced dental caries or suitable proxy for reduced caries risk.

SOURCES

PubMed, Scopus, EMBASE, and Web of Science databases were searched using search terms from previous searches.

STUDY SELECTION

All authors collectively agreed which studies to include after applying the exclusion/inclusion criteria. Eighteen studies were retrieved and analyzed. The studies were graded according to a National Institutes of Health grading system. Three authors decided on the final list of publications suitable for meta-analysis, and the meta-analysis was carried out using the public domain R statistical program.

RESULTS

After applying more specific inclusion criteria and assessment, out of 18 retrieved studies, 5 clinical trials and 8 in situ trials were included in the meta-analysis.

CONCLUSIONS

The evidence for the effectiveness of fluoride-free, hydroxyapatite-containing oral care products in reducing dental caries, both from RCTs and in situ clinical trials, has expanded. More studies now show that hydroxyapatite is effective as an anti-caries active ingredient in the absence of fluoride.

CLINICAL SIGNIFICANCE

As a sole active ingredient, considered safe if swallowed, hydroxyapatite is an ideal substitute for fluoride in toothpaste and mouthwash tailored for young children, and new data as presented in this review, demonstrated that hydroxyapatite-based oral care products can be used by people of all ages.

Effect of an experimental desensitizer with a hydroxyapatite-capsaicin composite applied before in-office dental bleaching on hydrogen peroxide diffusion, color and surface changes

OBJECTIVE

To evaluate a prior application of an experimental desensitizer containing a hydroxyapatite-capsaicin composite (HAp-CAP) in different concentrations on hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE) and on physical and chemical alterations of the enamel surface after in-office bleaching.

MATERIALS AND METHODS

Forty sound premolars were randomized in five groups according to each experimental condition (n = 8): no bleaching (negative control), only bleaching (positive control), 0.1%, 1% and 5% of HAp-CAP. Four groups were submitted to in-office bleaching (HP 35%) post-desensitizer application. The HP concentration (µg/mL) on the pulp chamber was measured by UV-Vis spectrophotometer. The BE was measured by digital spectrophotometer (ΔEab, ΔE00 and ΔWID) before and after 7 days bleaching. Enamel tooth fragments obtained from twenty molars were submitted to the same experimental conditions and analyzed using FE-SEM and EDS, Vickers microhardness (VHN), Raman spectroscopy, and nanoroughness (Ra) by AFM to evaluate morphologic and chemical changes on enamel surface. All data were submitted to statistical analysis (α = 0.05).

RESULTS

The groups treated with HAp-CAP exhibited a lower concentration of HP in the pulp chamber compared to only bleaching group (p < 0.05). There were no significant differences observed in BE between HAp-CAP groups and only bleaching group (p > 0.05). Only HAp-CAP 5% showed no significant differences in VHN values when compared to no bleaching group (p > 0.05). There were no significant differences among any group in Ra values (p > 0.05). The groups submitted to HAp-CAP showed a higher mineral concentration when compared to only bleaching group (p < 0.05).

CONCLUSION

Desensitizers containing HAp-CAP up to 5% effectively reduce HP diffusion into the pulp chamber after in-office bleaching, without interfering to BE and Ra, as well as prevent enamel demineralization.

CLINICAL RELEVANCE

The use of desensitizers containing HAp-CAP during in-office bleaching treatments offers a promising approach to reduce the risk of pulp irritation caused by hydrogen peroxide diffusion, without compromising the bleaching effectiveness or causing surface roughness.

The clinical and microbiological efficacy of a zinc-citrate/hydroxyapatite/potassium-citrate containing toothpaste: a double-blind randomized controlled clinical trial

OBJECTIVES

To evaluate the antibacterial efficacy of two fluoride-containing (1450 ppm F) toothpastes with or without zinc-citrate (ZCT), hydroxyapatite (HAP) and potassium-citrate (KCit); to assess and compare their clinical effects in terms of tooth sensitivity, plaque accumulation and gingivitis, as well as patients' satisfaction.

MATERIALS AND METHODS

Healthy, adult patients were selected and randomly assigned to two groups (n = 50): Experimental: ZCT-, HAP-, KCit- and fluoride-containing toothpaste; Control: fluoride-containing toothpaste. Salivary counts of Streptococcus mutans (S. mutans), plaque and gingival index, as well as clinically diagnosed sensitivity were recorded at baseline, and after 4 weeks. A custom-made questionnaire was used to assess patients' self-reported sensitivity (baseline and after 4 weeks) and overall satisfaction with the tested toothpastes. Data were statistically analyzed (α = 0.05).

RESULTS

After 4 weeks, a statistically significant salivary reduction of S. mutans was observed in both groups (p = 0.001). Furthermore, the percentage of S. mutans decrease was significantly higher in Experimental group (p = 0.014). There were no statistically significant differences between the groups in terms of plaque and gingival index (p > 0.05). After 4 weeks, the self-reported tooth sensitivity was lower in Experimental group (p < 0.001).

CONCLUSIONS

Both toothpastes showed good antimicrobial effect after 4 weeks; however, the toothpaste containing ZCT, HAP, KCit and fluoride was found to be more effective in reducing the salivary counts of S. mutans than the product containing fluoride alone.

CLINICAL RELEVANCE

Toothpaste containing ZCT, HAP, KCit and fluoride can be recommended for patients at risk for developing caries and may also be beneficial for individuals experiencing dental sensitivity.

Biomineralization and remineralizing potential of toothpastes containing nanosized β-calcium glycerophosphate: an in vitro study

To evaluate the effect of 1100 ppm F toothpastes supplemented with micrometric or nanosized β-CaGP (β-CaGPm/β-CaGPn) on artificial enamel remineralization, using a pH cycling model. Enamel blocks with artificial caries were randomly allocated into ten groups (n = 10), according to the toothpastes: without fluoride/β-CaGPm/β-CaGPn (negative control); 1100 ppm F (1100F); 1100F plus 0.125%, 0.25%, 0.5%, and 1.0% of β-CaGPm or β-CaGPn. The blocks were treated 2×/day with slurries of toothpastes. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); integrated mineral loss (ΔIMR); fluoride (F), calcium (Ca), and phosphorus (P) concentrations in the enamel; polydispersity index (PdI); and zeta potential (Zp) were determined. The data were analyzed by ANOVA (p < 0.001). For Zp/PdI, no significance was observed when comparing the means (p > 0.001). The treatment with 1100F-0.25%β-CaGPn led to %SHR ∼57 higher when compared to the 1100F group (p < 0.001). The lowest ΔKHN was observed for the 1100F-0.25%β-CaGPn group (p < 0.001). The ΔIMR was lower (∼201%) for the 1100F-0.25%β-CaGPn when compared to 1100F (p < 0.001). The association of β-CaGPm and β-CaGPn to 1100F did not influence its F concentration (p > 0.001). The highest increase in Ca and P was observed for 1100F-0.25%β-CaGPn (p < 0.001). The addition of 0.25%β-CaGPn to 1100F toothpaste was able to promote an additional remineralizing effect of artificial caries lesions.

Oral Microbiome: A Review of Its Impact on Oral and Systemic Health

PURPOSE OF REVIEW

This review investigates the oral microbiome's composition, functions, influencing factors, connections to oral and systemic diseases, and personalized oral care strategies.

RECENT FINDINGS

The oral microbiome is a complex ecosystem consisting of bacteria, fungi, archaea, and viruses that contribute to oral health. Various factors, such as diet, smoking, alcohol consumption, lifestyle choices, and medical conditions, can affect the balance of the oral microbiome and lead to dysbiosis, which can result in oral health issues like dental caries, gingivitis, periodontitis, oral candidiasis, and halitosis. Importantly, our review explores novel associations between the oral microbiome and systemic diseases including gastrointestinal, cardiovascular, endocrinal, and neurological conditions, autoimmune diseases, and cancer. We comprehensively review the efficacy of interventions like dental probiotics, xylitol, oral rinses, fluoride, essential oils, oil pulling, and peptides in promoting oral health by modulating the oral microbiome.

SUMMARY

This review emphasizes the critical functions of the oral microbiota in dental and overall health, providing insights into the effects of microbial imbalances on various diseases. It underlines the significant connection between the oral microbiota and general health. Furthermore, it explores the advantages of probiotics and other dental care ingredients in promoting oral health and addressing common oral issues, offering a comprehensive strategy for personalized oral care.

Orthodontic management of amelogenesis imperfecta: A case report

Key Clinical Message

Amelogenesis imperfecta (AI) is a rare developmental anomaly characterized by poorly developed or absent tooth enamel, which complicates orthodontic treatment due to weak enamel-bracket bond strength. This case report presents a successful management of AI using fixed orthodontic appliances and prosthodontic rehabilitation.

Abstract

Amelogenesis imperfecta (AI) causes enamel defects, complicating oral hygiene, reducing masticatory function and lowering self-esteem. This case report details an 18-year-old female with AI who underwent fixed orthodontic treatment followed by prosthodontic rehabilitation. The multidisciplinary approach restored function and aesthetics, significantly improving her quality of life.

Caries Etiology and Preventive Measures

Caries is a widespread disease in both children and adults. Caries is caused by the conversion of fermentable carbohydrates by plaque bacteria into acids on the tooth surface. Thus, it is important to focus on sugar reduction and plaque control. For efficient plaque removal/control, state-of-the-art toothpastes contain various active ingredients such as antimicrobial agents (e.g., chlorhexidine, stannous salts, and zinc salts), abrasives (e.g., calcium carbonate, calcium phosphates, and hydrated silica), surfactants (e.g., sodium lauryl sulfate and sodium methyl cocoyl taurate), and natural compounds (e.g., polyphenols and xylitol). Agents with pH-buffering and calcium-releasing properties (e.g., calcium carbonate and calcium phosphates) and biomimetic actives (e.g., hydroxyapatite) reverse the effects of the acids. Additionally, modern toothbrushes (i.e., electric toothbrushes) as well as dental floss and interdental brushes significantly help remove plaque from dental surfaces including interproximal surfaces. In conclusion, modern concepts in caries prevention should focus not only on tooth remineralization alone but also on the control of all the key factors involved in caries development.

Case Report on Caries Assessment Using Intraoral Scanner Compared with Bitewing Radiographs

Dental caries remains one of the main reasons patients seeing their dentist. They either show up for preventive measures, diagnostics, or treatment of present caries lesions. To date, diagnostics are performed visually, supported by using bitewing radiographs. While radiographic diagnostics should only be performed on a biannual basis, and some caries process will not be seen with visual diagnostics, there remains a lack in regular checkups. Therefore, different technical applications can be used for regular diagnostics. One of those is the near-infrared imaging (NIRI) technology. In this case report, a patient presented with incipient caries lesions. These lesions were diagnosed visually, radiographically, and using NIRI. After diagnosis of incipient caries lesions, the patient was advised to use a hydroxyapatite toothpaste and a hydroxyapatite gel for the remineralization of the lesions and prevention of caries progression. The patient was followed up for 6 months with regular checkups in between. Visual diagnostics and NIRI were used to detecting the caries progress. After 6 months, bitewing radiographs were used in addition. In this clinical investigation we were able to show for the first time that NIRI and bitewing radiographs are able to detect and follow incipient caries lesions. Additionally, this study highlights that hydroxyapatite-containing oral care products are able to arrest and remineralize the caries process.

A coating machine for coating filaments with bioactive nanomaterials for extrusion 3D printing

Extrusion printing based on biocompatible filaments offers a wide variety of targeted medical and dental applications in the area of personalized medicine, if combined with bioactive nanomaterials. However, this requires filament to be coated with bioactive nanomaterial. This study introduces a concept of a machine to coat filament with bioactive nanomaterials and its application. A machine was constructed with modules manufactured using additive manufacturing. A filament spool of polylactide (PLA) or glycol-modified polyethylene terephthalate (PETG) was transported through a copper tube, with the outer surface of the filament heated to the appropriate glass transition temperature to incorporate added nanomaterials such as nano-hydroxyapatite (nHA) or nano-fluorapatite(nFA). Coatings with nHA led to an increase in diameter of around 3 μm, while coatings with nFA increased the diameter by 4 μm. Printing of cubes with a standard extrusion printer platform using PLA or PETG filaments with added nHA or nFA has been successfully carried out. Scanning electron microscope (SEM) images of coated filaments and printed cubes showed an irregular distribution of nHA or nFA, which could be verified by energy dispersive X-ray analysis (EDX). Adding and adjusting bioactive nanomaterials to filament with a coating machine for filament proved to generate printable filaments. With the wide range of possible applications by different nanomaterials it is anticipated that extrusion printing can cover needs for personalized medicine and dentistry.

Remineralizing effect of the association of nano-hydroxyapatite and fluoride in the treatment of initial lesions of the enamel: A systematic review

OBJECTIVE

Assessed the effect of dental products containing nano-hydroxyapatite (nano-HA) + fluoride on the remineralization of white spot lesions (WSL) in vivo or in situ.

METHODS

Seven databases were explored using a two-pronged approach (intervention/treatment). After screening, full-text assessment, and further exclusion, the qualitative synthesis of five studies (four clinical and one in situ) was performed. Based on the Cochrane collaboration guidelines relevant data of the studies were collected and summarized. The Cochrane risk of bias tool for randomized trials (RoB 2.0) was used to appraise the studies' methodological quality and the GRADE guidelines to assess their level of evidence. The RoB 2.0 domains were rated on their risk of bias (RoB) as low, high, or with some concerns, and an adaptation of the tool was used to the in situ study.

RESULTS

The included studies assessed 151 WSL in anterior permanent teeth, on patients with varying ages. The protocol application, treatment length (7d-12 w), and control groups varied greatly between the studies making the performance of a quantitative analysis unfeasible. The general RoB of the clinical studies was classified as being of low risk (n = 2) or some concerns (n = 2). The in situ study was considered as being of low risk. The level of the evidence was moderate. Most of the studies found moderate evidence regarding the superiority of this association in clinical settings.

CONCLUSION

Even with the nano-HA + fluoride promising results for the remineralization treatment of WSL, due to the restricted number of studies and types of products, its extended use cannot be recommended based on the current systematic review, especially when considering the moderate level of the evidence found.

CLINICAL SIGNIFICANCE

Due to the biocompatibility and higher surface coverage of nano-HA and the remineralization capacity of fluoride formulations, the association of these elements to remineralize WSL has been positively reported. After the collection and qualitative appraise of the data, the clinical evidence of the use of these dental products is promising but limited.

Efficacy of F-ACP-Containing Dental Mousse in the Remineralization of White Spot Lesions after Fixed Orthodontic Therapy: A Randomized Clinical Trial

Fixed appliance (FA) therapy predisposes patients to white spot lesions (WSLs). The F-ACP complex (amorphous calcium phosphate nanoparticles enriched with carbonate and fluorine and coated with citrate) has been effective for in vitro enamel remineralization. The aim of this study was to evaluate the efficacy of the F-ACP complex in remineralizing WSLs after FA therapy. One hundred and six adolescents (aged 12-20 years) were randomized into study and control groups after FA therapy. Patients in the study group were advised to use dental mousse containing F-ACP applied within Essix retainers for six months. The presence of WSLs was recorded at baseline (T0), 3 months (T1), and 6 months (T2) according to the International Caries Detection and Assessment System (ICDAS). Visual Plaque Index (VPI) and Gingival Bleeding Index (GBI) were recorded. Among 106 study participants, 91 (52 and 39 in study and control groups, respectively) completed the study. The results showed that the ICDAS score was significantly lower (p < 0.001) in the study group than in the control group between T0 and T2. The application of mousse containing the F-ACP complex inside Essix retainers for six months is effective in remineralizing white spot lesions in patients after FA therapy without side effects.

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.

Prevention of Dental Caries: A Review on the Improvements of Toothpaste Formulations from 1900 to 2023

Modern toothpastes are complex formulations with various ingredients. The aim of this study was to analyze the improvement of toothpaste formulations from 1900 to 2023 focusing on active ingredients with remineralizing, antibacterial, or plaque-removing effects, and to discuss their influence on caries prevention. For this, worldwide patent applications were searched using the international database Espacenet from the European Patent Office. Additionally, toothpaste products were searched using the Mintel product database from 1996 to 2023. The searched ingredients were (in alphabetical order): calcium carbonate, calcium phosphates, hydrated silica, sodium fluoride, sodium lauryl sulfate, triclosan, xylitol, and zinc salts as they are known from the scientific literature to be remineralizing or antibacterial/antiplaque agents. It was shown that the number of patent applications containing these ingredients significantly increased since the 1970s. As these ingredients have remineralizing, antibacterial, or plaque-removing effects, they all can contribute to caries prevention. In conclusion, and within the limitations of this approach, this study shows that toothpaste formulations have greatly improved over the past decades by using various active anticaries ingredients.

Nanotechnology in toothpaste: Fundamentals, trends, and safety

Several studies have revealed that healthcare nanomaterials are widely used in numerous areas of dentistry, including prevention, diagnosis, treatment, and repair. Nanomaterials in dental cosmetics are utilized to enhance the efficacy of toothpaste and other mouthwashes. Nanoparticles are added to toothpastes for a variety of reasons, including dental decay prevention, remineralization, hypersensitivity reduction, brightening, and antibacterial qualities. In this review, the benefits and uses of many common nanomaterials found in toothpaste are outlined. Additionally, the capacity and clinical applications of nanoparticles as anti-bacterial, whitening, hypersensitivity, and remineralizing agents in the treatment of dental problems and periodontitis are discussed.

Iontophoresis use for increasing drug penetration into root canals and dentinal tubules: A proof-of-concept study

INTRODUCTION

The success of endodontic treatment depends on the significant disinfection of the root canal system, its irregularities, and dentinal tubules. However, achieving complete disinfection remains challenging, with frequent failures and occurrence of secondary infections. Here, we propose using iontophoresis to increase the penetration and distribution of disinfecting agents into root canals, using methylene blue for proof-of-concept.

METHODS

The marker was applied in bovine root canals, and the radial distribution of the dye in the dentinal tubules was evaluated by optical microscopy. Iontophoresis was applied at 0.5 and 1.5 mA for 5 and 15 min.

RESULTS

A significant statistical difference (p < 0.05) was observed in the marker penetration between passive and iontophoretic applications. Both current density and application time had an important effect on methylene blue distribution, with a greater efficacy delivery to the apical region achieved after 1.5 mA for 5 min or 0.5 mA for 15 min, showing longer application time can compensate for lower application current.

CONCLUSION

Iontophoresis increases the penetration and distribution of methylene blue into bovine root canals and dentinal tubules, including its innermost portions.

CLINICAL SIGNIFICANCE

Iontophoresis has shown to be a promising technique for root canal and dentinal tubule disinfection.

Doses of fluoride toothpaste for children up to 24 months

AIM

The aim of this study was to test the dose of fluoride toothpaste by parents for their children aged up to 24 months.

METHODS

Parents who use fluoride toothpastes for their children were asked to dose two commercially available toothpastes (A and B) with 1000 ppm fluoride each for their children as they would normally do at home. The toothpaste amounts were weighed, and as reference, the weight of an 'optimal' grain of rice-size amount of each toothpaste was used.

RESULTS

61 parents dosed a mean of 0.263 ± 0.172 g toothpaste A and 0.281 ± 0.145 g toothpaste B. The parents' mean doses were 5.9 times higher for toothpaste A and 7.2 times higher for toothpaste B than an 'optimal' grain of rice-size amount (the reference dose as recommended). The difference between parent's and reference dose was statistically significant (p < 0.001). Moreover, 39.3% of parents were not aware about conditions of use and warnings that have to be printed on the package of fluoride toothpastes.

CONCLUSION

In this study, parents significantly overdosed the toothpaste for their children. To avoid fluoride intake from toothpaste, parents can choose fluoride-free alternatives for the oral care of their infants and toddlers.

Bioactivity and remineralization potential of modified glass ionomer cement: A systematic review of the impact of calcium and phosphate ion release

This systematic review investigates the effectiveness of calcium and phosphate ions release on the bioactivity and remineralization potential of glass ionomer cement (GIC). Electronic databases, including PubMed-MEDLINE, Scopus, and Web of Science, were systematically searched according to PRISMA guidelines. This review was registered in the PROSPERO database. Five eligible studies on modifying GIC with calcium and phosphate ions were included. The risk of bias was assessed using the RoBDEMAT tool. The incorporation of these ions into GIC enhanced its bioactivity and remineralization properties. It promoted hydroxyapatite formation, which is crucial for remineralization, increased pH and inhibited cariogenic bacteria growth. This finding has implications for the development of more effective dental materials. This can contribute to improved oral health outcomes and the management of dental caries, addressing a prevalent and costly oral health issue. Nevertheless, comprehensive longitudinal investigations are needed to evaluate the clinical efficacy of this GIC's modification.

Comparative evaluation of remineralization potential of four different remineralization agents on human enamel: An in vitro study

Aim

The study aimed to assess the remineralizing potential of four different commercially available agents using a Scanning Electron Microscope (SEM), energy dispersive X-ray (EDX) analysis, and Vickers Microhardness (VMH) Test.

Materials and Methods

Forty-four specimens (n = 11 per group) were prepared from extracted teeth. A window of 6 mm × 4 mm was made on all the specimens that represented three zones, namely, sound enamel, demineralized enamel, and remineralized enamel. The zone for demineralized enamel was subjected to four different remineralizing agents; casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF), tricalcium phosphate fluoride (TCP-F), calcium sucrose phosphate (CSP), and self-assembling peptide (P11-4). Remineralization (REM) was assessed using VMH; the structural changes were assessed using SEM that was analyzed using EDX analysis. The specimens were subjected to a newer regimen of demineralization. One-way ANOVA followed by post hoc Tukey test was used with a level of significance at P ≤ 0.05.

Results

There were no significant differences in VMH between the groups for sound enamel (P = 0.472) and demineralized enamel (P = 0.116). VMH was statistically significantly more for P11-4 and the least for CPP-ACPF (P = 0.011). A post hoc analysis revealed higher VMH for P11-4 compared to CPP-ACPF (P = 0.014) and TCP-F (P = 0.035). SEM showed a homogeneous layer of minerals for all groups except CPP-ACPF. TCP-F reported a higher degree of REM, followed by P11-4 as assessed using EDX analysis.

Conclusion

Self-assembling peptide (P11-4) exhibited a higher degree of REM than other remineralizing agents followed by CSP.

Nanoparticles and Their Antibacterial Application in Endodontics

Root canal treatment represents a significant challenge as current cleaning and disinfection methodologies fail to remove persistent bacterial biofilms within the intricate anatomical structures. Recently, the field of nanotechnology has emerged as a promising frontier with numerous biomedical applications. Among the most notable contributions of nanotechnology are nanoparticles, which possess antimicrobial, antifungal, and antiviral properties. Nanoparticles cause the destructuring of bacterial walls, increasing the permeability of the cell membrane, stimulating the generation of reactive oxygen species, and interrupting the replication of deoxyribonucleic acid through the controlled release of ions. Thus, they could revolutionize endodontics, obtaining superior results and guaranteeing a promising short- and long-term prognosis. Therefore, chitosan, silver, graphene, poly(lactic) co-glycolic acid, bioactive glass, mesoporous calcium silicate, hydroxyapatite, zirconia, glucose oxidase magnetic, copper, and zinc oxide nanoparticles in endodontic therapy have been investigated in the present review. The diversified antimicrobial mechanisms of action, the numerous applications, and the high degree of clinical safety could encourage the scientific community to adopt nanoparticles as potential drugs for the treatment of endodontic diseases, overcoming the limitations related to antibiotic resistance and eradication of the biofilm.

Effect of Two Remineralizing Agents on Dentin Microhardness of Non-Caries Lesions

Statement of the Problem

The prevalence of non-carious dentin lesions is on the rise mainly due to improved life expectancy. Successful management of these lesions is often challenging, and given that dentin can be remineralized, adverse consequences due to progression of these lesions can be prevented or minimized as such.

Purpose

This study aimed to assess the effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and Remin-Pro remineralizing agents on dentin microhardness of non-carious dentin lesions.

Materials and Method

This in vitro, experimental study evaluated 36 extracted sound human premolars. The teeth were decoronated at the cementoenamel junction. Enamel was removed, and dentin was exposed at the cervical third of the buccal surface. The primary microhardness of dentin was then measured. The teeth, standardized in terms of dentin microhardness, then underwent demineralization by acid etching and were subjected to microhardness test again. They were then randomized into three groups for treatment with CPP-ACP, Remin-Pro, and artificial saliva (control), and dentin microhardness was measured for the third time after treatment. Data were analyzed using ANOVA.

Results

Within group comparisons showed a significant difference in microhardness at the three time points in all three groups (p< 0.005). Between-group comparisons revealed that the microhardness of the three groups was not significantly different at baseline or after demineralization. However, the microhardness of the three groups was significantly different after the intervention (p= 0.000). Pairwise comparisons revealed significantly higher microhardness in the CPP-ACP group than the other two groups (p= 0.003). Remin-Pro and the control groups were not significantly different in this respect (p= 0.340).

Conclusion

CPP-ACP can be used for remineralization of non-caries dentin lesions; however, Remin-Pro does not appear to be effective for this purpose.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2022 dental literature to briefly touch on several topics of interest to modern restorative dentistry. Each committee member brings discipline-specific expertise in their subject areas that include (in order of the appearance in this report): prosthodontics; periodontics, alveolar bone, and peri-implant tissues; dental materials and therapeutics; occlusion and temporomandibular disorders; sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence the daily dental treatment decisions of the reader with an emphasis on innovations, new materials and processes, and future trends in dentistry. With the tremendous volume of literature published daily in dentistry and related disciplines, this review cannot be comprehensive. Instead, its purpose is to update interested readers and provide valuable resource material for those willing to subsequently pursue greater detail on their own. Our intent remains to assist colleagues in navigating the tremendous volume of newly minted information produced annually. Finally, we hope that readers find this work helpful in managing patients.

Remineralization Induced by Biomimetic Hydroxyapatite Toothpastes on Human Enamel

This work aimed to compare the effect of four new toothpastes (P1-P4) based on pure and biomimetic substituted nano-hydroxyapatites (HAPs) on remineralization of human enamel. Artificially demineralized enamel slices were daily treated for ten days with different toothpastes according to the experimental design. Tooth enamel surfaces were investigated using atomic force microscope (AFM) images and surface roughness (Ra) determined before and after treatment. The surface roughness of enamel slices was statistically analyzed by one-way ANOVA and Bonferroni's multiple comparison test. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) data revealed the HAP structure with crystal sizes between 28 and 33 nm and crystallinity between 29 and 37%. The average size of HAP particles was found to be between 30 and 40 nm. The Ra values indicated that P3 (HAP-Mg-Zn-Sr-Si) toothpaste was the most effective after 10 days of treatment, leading to the lowest mean roughness. The P3 and P2 (HAP) toothpastes were found to be effective in promoting remineralization. Specifically, their effectiveness can be ranked as follows: P3 = P2 > P4 (HAP-Mg-Zn-Si) > P1 (HAP-Zn), considering both the chemical composition and the size of their constitutive nanoparticles. The proposed toothpastes might be used successfully to treat early tooth decay.

Engineered Biomaterials Trigger Remineralization and Antimicrobial Effects for Dental Caries Restoration

Dental caries is the most prevalent chronic disease globally, significantly impacting individuals' quality of life. A key reason behind the failure of implanted restorations is their biological inactivity, meaning they are unable to form crosslinks with the surrounding tooth structures, thus making patients susceptible to implant loss and recurrent tooth decay. For the treatment of caries, antibacterial medicine and remineralization are effective means of treating the recurrence of caries. Owing to the rapid progression in the biomaterials field, several biomaterials have been reported to display antimicrobial properties and aid in dentin remineralization. Bioactive materials hold considerable potential in diminishing biofilm accumulation, inhibiting the process of demineralization, enabling dentin remineralization, and combating bacteria related to caries. Bioactive materials, such as fluoride, amorphous calcium phosphate, bioactive glass, collagen, and resin-based materials, have demonstrated their effectiveness in promoting dentin remineralization and exerting antibacterial effects on dental caries. However, the concentration of fluoride needs to be strictly controlled. Although amorphous calcium phosphate can provide the necessary calcium and phosphorus ions for remineralization, it falls short in delivering the mechanical strength required for oral mastication. Resin-based materials also offer different advantages due to the complexity of their design. In this review, we delve into the application of advanced bioactive materials for enhancing dentin remineralization and antibacterial properties. We eagerly anticipate future developments in bioactive materials for the treatment of dental caries.

Caries-preventing effect of a hydroxyapatite-toothpaste in adults: a 18-month double-blinded randomized clinical trial

Background

Dental caries is a worldwide challenge for public health. The aim of this 18-month double-blinded, randomized, clinical trial was to compare the caries-preventing effect of a fluoride-free, hydroxyapatite toothpaste (test) and a toothpaste with sodium fluoride (1450 ppm fluoride; positive control) in adults.

Methods

The primary endpoint was the percentage of subjects showing no increase in overall Decayed Missing Filled Surfaces (DMFS) index. The study was designed as non-inferiority trial. Non-inferiority was claimed if the upper limit of the exact one-sided 95% confidence interval for the difference of the primary endpoint DMFS between test and control toothpaste was less than the predefined margin of non-inferiority (Δ ≤ 20%).

Results

In total, 189 adults were included in the intention-to-treat (ITT) analysis; 171 subjects finished the study per protocol (PP). According to the PP analysis, no increase in DMFS index was observed in 89.3% of subjects of the hydroxyapatite group and 87.4% of the subjects of the fluoride group. The hydroxyapatite toothpaste was not statistically inferior to a fluoride toothpaste with regard to the primary endpoint.

Conclusion

Hydroxyapatite was proven to be a safe and efficient anticaries agent in oral care.

Clinical trial registration

NCT04756557.

An In-Vitro Comparative Study of Fluoride Varnish and Two Calcium-Containing Fluoride Products on the Remineralization of Primary Teeth Enamel

Objectives: To compare the effectiveness of fluoride varnish and two calcium-based fluoride products on the remineralization of primary teeth enamel. Materials and Methods: Surface-microhardness (SMH) of 36 extracted anterior primary teeth was measured by Vickers test (50gr/5 seconds) to provide a baseline for later comparisons. All teeth were immersed in demineralizing solution for 96 hours to create caries-like lesions and SMH was determined for the artificially-induced caries. The teeth were randomly assigned to three groups consisting of 5% fluoride varnish once daily/10 seconds, Clinpro™ 5000 toothpaste once daily/2 minutes, and Remin Pro cream once daily/3 minutes for 28 days. All specimens were kept in artificial saliva with pH cycling during the study period. After remineralization, SMH was evaluated for the last time. Data were analyzed by one-way ANOVA, Mauchly's sphericity, and RM-ANOVA with Bonferroni correction for inter-and- intra-group comparisons at the three stages of the study. Results: Neither the baseline SMH nor the SMH of the artificially created caries showed significant differences among the samples (P>0.05). The post-treatment SMH was highest in the Clinpro group (296.4±73.1kgf/mm2), followed by Remin Pro (283.8±119.3kgf/mm2), and varnish (270.9±78.3 kgf/mm2). There was no significant difference among the groups after treatment (P>0.05). We also did not observe a significant difference among the three different study stages (P>0.05). Conclusion: Within the limitations of this in-vitro study, daily application of low fluoride-calcium compound seems to be as effective as the professional use of fluoride varnish or high-content fluoride toothpaste in remineralizing initial caries of primary teeth.

Biomimetic Enamel Regeneration Using Self-Assembling Peptide P11-4

The recent understanding of the etiology and pathology of dental caries has shifted its treatment from invasive drill and fill conventional strategies to noninvasive and/or minimally invasive approaches. Guided tissue regeneration (GTR) is a well-established therapeutic approach in medicine and periodontal and oral surgery. Recently, the concept of biomimetic regeneration has been further expanded to treat the loss of hard dental tissues. Self-assembling peptides have emerged as a promising biomaterial for biomimetic regeneration due to their ability to construct a protein scaffold in the body of early carious lesions and provide a matrix that promotes remineralization. This review article accompanies the development of self-assembling peptide P11-4 for the treatment of initial carious lesions. In vitro and in vivo studies on the safety, clinical applicability, and efficacy of P11-4 are discussed. Furthermore, different treatment options and potential areas of application are presented.

An investigation on the fabrication and characterization of friction stir processed nano-HAp reinforced AZ91D magnesium matrix surface composite for bio-implants

In the present research, friction stir processed (FSPed) nano-hydroxyapatite reinforced AZ91D magnesium matrix surface composite has been developed with improved ultimate tensile strength (UTS) and biological performance, which are needed for the bio-implants. Nano-hydroxyapatite reinforcement with varying proportions (5.8%, 8.3%, and 12.5%) was introduced into the AZ91-D parent material (PM) by the grooving method with different grooves of 0.5, 1 & 1.5 mm of width and 2 mm depth machined on the surface of the PM. Taguchi's L-9 orthogonal array was employed to optimize the processing variables for enhancing the UTS of the developed composite material. The optimum parameters were discovered to be the tool rotational speed of 1000 rpm, transverse speed of 50 mm/min, and 12.5% reinforcement concentration. The results revealed that the tool rotational speed contributes the highest effect (43.69%) on UTS, followed by the reinforcement percentage (37.49%) and transverse speed (18.31%). The FSPed samples at the optimized parameter setting confirmed the enhancement of 30.17% and 31.86% in UTS and micro-hardness, respectively, compared to the PM. Cytotoxicity of the optimized sample was also found superior compared to the other FSPed samples. The optimized FSPed composite's grain size was 6.88 times smaller than the AZ91D parent matrix material. The improved mechanical and biological performances of the composites are attributed to the significant grain refinement and proper dispersion of the nHAp reinforcement in the matrix.

Biological Response of Human Gingival Fibroblasts to Zinc-Doped Hydroxyapatite Designed for Dental Applications-An In Vitro Study

This study aimed to investigate the biological response induced by hydroxyapatite (HAp) and zinc-doped HAp (ZnHAp) in human gingival fibroblasts and to explore their antimicrobial activity. The ZnHAp (with xZn = 0.00 and 0.07) powders, synthesized by the sol-gel method, retained the crystallographic structure of pure HA without any modification. Elemental mapping confirmed the uniform dispersion of zinc ions in the HAp lattice. The size of crystallites was 18.67 ± 2 nm for ZnHAp and 21.54 ± 1 nm for HAp. The average particle size was 19.38 ± 1 nm for ZnHAp and 22.47 ± 1 nm for HAp. Antimicrobial studies indicated an inhibition of bacterial adherence to the inert substrate. In vitro biocompatibility was tested on various doses of HAp and ZnHAp after 24 and 72 h of exposure and revealed that cell viability decreased after 72 h starting with a dose of 31.25 µg/mL. However, cells retained membrane integrity and no inflammatory response was induced. High doses (such as 125 µg/mL) affected cell adhesion and the architecture of F-actin filaments, while in the presence of lower doses (such as 15.625 µg/mL), no modifications were observed. Cell proliferation was inhibited after treatment with HAp and ZnHAp, except the dose of 15.625 µg/mL ZnHAp at 72 h of exposure, when a slight increase was observed, proving an improvement in ZnHAp activity due to Zn doping.

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

Silk fibroin (SF) is an excellent protein-based biomaterial produced by the degumming and purification of silk from cocoons of the Bombyx mori through alkali or enzymatic treatments. SF exhibits excellent biological properties, such as mechanical properties, biocompatibility, biodegradability, bioabsorbability, low immunogenicity, and tunability, making it a versatile material widely applied in biological fields, particularly in tissue engineering. In tissue engineering, SF is often fabricated into hydrogel form, with the advantages of added materials. SF hydrogels have mostly been studied for their use in tissue regeneration by enhancing cell activity at the tissue defect site or counteracting tissue-damage-related factors. This review focuses on SF hydrogels, firstly summarizing the fabrication and properties of SF and SF hydrogels and then detailing the regenerative effects of SF hydrogels as scaffolds in cartilage, bone, skin, cornea, teeth, and eardrum in recent years.

Assessment of the Remineralizing Potential of Biomimetic Materials on Early Artificial Caries Lesions after 28 Days: An In Vitro Study

This study aimed to evaluate the loss of mineral content in the enamel surface in early artificial lesions and to assess the remineralizing potential of different agents by means of SEM coupled with energy-dispersive X-ray analysis (EDX). The analysis was performed on the enamel of 36 molars divided into six equal groups, in which the experimental ones (3-6) were treated using remineralizing agents for a 28-day pH cycling protocol as follows: Group 1, sound enamel; Group 2, artificially demineralized enamel; Group 3, CPP-ACP treatment; Group 4, Zn-hydroxyapatite treatment; Group 5, NaF 5% treatment; and Group 6, F-ACP treatment. Surface morphologies and alterations in Ca/P ratio were evaluated using SEM-EDX and data underwent statistical analysis (p < 0.05). Compared with the sound enamel of Group 1, the SEM images of Group 2 clearly showed loss of integrity, minerals, and interprismatic substances. Groups 3-6 showed a structural reorganization of enamel prisms, interestingly comprising almost the entire enamel surface. Group 2 revealed highly significant differences of Ca/P ratios compared with other groups, while Groups 3-6 showed no differences with Group 1. In conclusion, all tested materials demonstrated a biomimetic ability in remineralizing lesions after 28 days of treatment.

Remineralization Strategies for Teeth with Molar Incisor Hypomineralization (MIH): A Literature Review

Molar incisor hypomineralization (MIH) is a highly prevalent dental developmental disorder with a significant health burden for patients and high treatment needs, yet no comprehensive review article on all remineralization systems as a non-invasive treatment approach for MIH has been published. Typical characteristics of MIH-affected teeth are a lower mineral density and lower hardness compared to healthy teeth leading to sensitivity and loss of function. Thus, the use of formulations with calcium phosphates to remineralize MIH-affected teeth is reasonable. This review presents an up-to-date overview of remineralization studies focusing on active ingredients investigated for remineralization of MIH, i.e., casein phosphopeptide amorphous calcium phosphate (CPP-ACP), casein phosphopeptide amorphous calcium fluoride phosphate (CPP-ACFP), hydroxyapatite, calcium glycerophosphate, self-assembling peptide, and fluoride. Overall, 19 studies (in vitro, in situ, and in vivo) were found. Furthermore, an additional search for studies focusing on using toothpaste/dentifrices for MIH management resulted in six studies, where three studies were on remineralization and three on reduction of sensitivity. Overall, the studies analyzed in this review showed that MIH-affected teeth could be remineralized using calcium phosphate-based approaches. In conclusion, calcium phosphates like CPP-ACP, calcium glycerophosphate, and hydroxyapatite can be used to remineralize MIH-affected teeth. In addition to MIH-remineralization, CPP-ACP and hydroxyapatite also offer relief from MIH-associated tooth sensitivity.

Tooth Whitening with Hydroxyapatite: A Systematic Review

A steadily increasing public demand for whiter teeth has resulted in the development of new oral care products for home use. Hydroxyapatite (HAP) is a new ingredient to whiten teeth. This systematic review focuses on the evidence of whether HAP can effectively whiten teeth. A systematic search using the PICO approach and PRISMA guidelines was conducted using PubMed, Scopus, Web of Science, SciFinder, and Google Scholar as databases. All study designs (in vitro, in vivo) and publications in foreign language studies were included. Of the 279 study titles that the searches produced, 17 studies met the inclusion criteria. A new "Quality Assessment Tool For In Vitro Studies" (the QUIN Tool) was used to determine the risk of bias of the 13 studies conducted in vitro. Moreover, 12 out of 13 studies had a low risk of bias. The in vivo studies were assigned Cochrane-based GRADE scores. The results in vitro and in vivo were consistent in the direction of showing a statistically significant whitening of enamel. The evidence from in vitro studies is rated overall as having a low risk of bias. The evidence from in vivo clinical trials is supported by modest clinical evidence based on six preliminary clinical trials. It can be concluded that the regular use of hydroxyapatite-containing oral care products effectively whitens teeth, but more clinical trials are required to support the preliminary in vivo evidence.

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.

Clinical Evidence of Biomimetic Hydroxyapatite in Oral Care Products for Reducing Dentin Hypersensitivity: An Updated Systematic Review and Meta-Analysis

Dentin hypersensitivity (DH) is a very common dental problem that can have a negative impact on the quality of life and can lead to invasive dental procedures. Prevention of DH and control of symptoms are highly desirable. Hydroxyapatite (HAP) has been shown in vitro to block dentinal tubules and in vivo to be a safe and effective additive in oral care products that reduce DH clinically. This study's aim was to conduct a systematic review and meta-analysis of the current evidence that HAP-containing oral care products reduce DH. Databases were searched, and only clinical trials in humans were included; studies conducted in vitro or on animals were not included. Publications in a foreign language were translated and included. We found 44 published clinical trials appropriate for systematic analysis. More than half of the trials had high-quality GRADE scores. HAP significantly reduced dentin hypersensitivity compared to placebo (39.5%; CI 95% [48.93; 30.06]), compared to fluoride (23%; CI 95% [34.18; 11.82]), and with a non-significant tendency compared to other desensitizing agents (10.2%; CI 95% [21.76; -19.26]). In conclusion, the meta-analysis showed that HAP added to oral care products is a more effective agent than fluoride in controlling dentin hypersensitivity and may be superior to other desensitizers.

Overview on Adjunct Ingredients Used in Hydroxyapatite-Based Oral Care Products

Hydroxyapatite, Ca₅(PO₄)₃(OH), is a biomimetic active ingredient, which is used in commercial oral care products such as toothpastes and mouthwashes worldwide. Clinical studies (in vivo) as well as in situ and in vitro studies have shown the preventive effects of hydroxyapatite in various field of oral care. In some products, hydroxyapatite is combined with other active ingredients, to achieve an additional antibacterial effect or to promote gum health. This review analyzes the efficacy of six selected natural and nature-inspired ingredients that are commonly used together with hydroxyapatite. These additional actives are either antibacterial (lactoferrin, xylitol, and zinc) or promote gum health (allantoin, bisabolol, and hyaluronic acid). A systematic literature search was performed, and all studies found on each ingredient were analyzed. In summary, all analyzed ingredients mentioned in this review are well described in scientific studies on their beneficial effect for oral health and can be used to expand the preventive effect of hydroxyapatite in oral care products.

Remineralization of molar incisor hypomineralization (MIH) with a hydroxyapatite toothpaste: an in-situ study

AIM

This randomized, double-blind, crossover, in-situ study, compared the efficacy of toothpastes based on microcrystalline hydroxyapatite (HAP; fluoride-free) or fluoride, in remineralizing molar incisor hypomineralization (MIH).

METHODS

Two lesion-bearing enamel blocks were produced from each of thirty extracted permanent molars diagnosed with MIH. Sixty produced blocks were randomly assigned to two groups (30/group): 20% HAP or 1450 ppm fluoride toothpaste. Each group was subdivided into, etched (n = 20), with lesion surface treated with 32% phosphoric acid-etchant for 5 s, and unetched (n = 10). Blocks were cemented into intra-oral appliances (2 blocks/appliance) worn full-time by 15 subjects. Subjects used the toothpastes in a two-phase crossover manner, lasting 14 days per phase, after one-week washout period. Baseline and post-treatment mineral density (MD) was quantified using microcomputed tomography.

RESULTS

Overall, both groups showed statistically significant (paired t-test; p < 0.001) net-gain when MD was compared pre-treatment and post-treatment. HAP: pre-treatment (1.716 ± 0.315) and post-treatment (1.901 ± 0.354), Fluoride: pre-treatment (1.962 ± 0.363) and post-treatment (2.072 ± 0.353). Independent t-test demonstrated a practically significantly (≥10%) higher percentage remineralization with HAP toothpaste (26.02 ± 20.68) compared with fluoride toothpaste (14.64 ± 9.60). Higher percentage remineralization was observed in etched than unetched samples.

CONCLUSION

The tested toothpaste based on hydroxyapatite can remineralize MIH lesions. Pre-treating the tooth surface with acid-etchant enhanced remineralization.

On the Application of Calcium Phosphate Micro- and Nanoparticles as Food Additive

The human body needs calcium and phosphate as essential nutrients to grow bones and teeth, but they are also necessary for many other biochemical purposes (e.g., the biosynthesis of phospholipids, adenosine triphosphate, ATP, or DNA). The use of solid calcium phosphate in particle form as a food additive is reviewed and discussed in terms of bioavailability and its safety after ingestion. The fact that all calcium phosphates, such as hydroxyapatite and tricalcium phosphate, are soluble in the acidic environment of the stomach, regardless of the particle size or phase, means that they are present as dissolved ions after passing through the stomach. These dissolved ions cannot be distinguished from a mixture of calcium and phosphate ions that were ingested separately, e.g., from cheese or milk together with soft drinks or meat. Milk, including human breast milk, is a natural source of calcium and phosphate in which calcium phosphate is present as nanoscopic clusters (nanoparticles) inside casein (protein) micelles. It is concluded that calcium phosphates are generally safe as food additives, also in baby formula.

Improved Enamel Acid Resistance Using Biocompatible Nano-Hydroxyapatite Coating Method

In this study, we attempted to develop a dental caries prevention method using a bioapatite (BioHap), an eggshell-derived apatite with nanoparticle size and biocompatibility, with a high-concentration fluoride tooth surface application method. The enamel acid resistance after the application of the proposed method was compared with that of a conventional topical application of fluoride using bovine tooth enamel as an example. The tooth samples were divided into three groups based on the preventive treatment applied, and an acid challenge was performed. The samples were evaluated for acid resistance using qualitative and quantitative analytical methods. The BioHap group demonstrated reduced enamel loss and improved micro-Vickers hardness, along with a thick coating layer, decreased reaction area depth, and decreased mineral loss value and lesion depth. The combination of BioHap with high-concentration fluoride led to the formation of a thick coating layer on the enamel surface and better suppression of demineralization than the conventional method, both qualitatively and quantitatively. The proposed biocompatible nano-hydroxyapatite coating method is expected to become a new standard for providing professional care to prevent dental caries.

Remineralization of Artificially Demineralized Human Enamel and Dentin Samples by Zinc-Carbonate Hydroxyapatite Nanocrystals

(1) Background: Decalcified enamel and dentin surfaces can be regenerated with non-fluoride-containing biomimetic systems. This study aimed to investigate the effect of a zinc carbonate-hydroxyapatite-containing dentifrice on artificially demineralized enamel and dentin surfaces. (2) Methods: Human enamel and dentin discs were prepared and subjected to surface demineralization with 30% orthophosphoric acid for 60 s. Subsequently, in the test group (n = 20), the discs were treated three times a day for 3 min with a zinc carbonate-hydroxyapatite-containing toothpaste (biorepair^®). Afterwards, all samples were gently rinsed with PBS (5 s) and stored in artificial saliva until next use. Samples from the control group (n = 20) received no dentifrice-treatment and were stored in artificial saliva, exclusively. After 15 days of daily treatment, specimens were subjected to Raman spectroscopy, energy-dispersive X-ray micro-analysis (EDX), white-light interferometry, and profilometry. (3) Results: Raman spectroscopy and white-light interferometry revealed no significant differences compared to the untreated controls. EDX analysis showed calcium phosphate and silicon dioxide precipitations on treated dentin samples. In addition, treated dentin surfaces showed significant reduced roughness values. (4) Conclusions: Treatment with biorepair^® did not affect enamel surfaces as proposed. Minor mineral precipitation and a reduction in surface roughness were detected among dentin surfaces only.

Evaluation of Enamel Acid Resistance and Whitening Effect of the CAP System

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained.

Incorporation of Fluoride into Human Teeth after Immersion in Fluoride-Containing Solutions

Toothpastes and mouth rinses contain fluoride as a protective agent against caries. The aim of this study was to determine the degree of fluoride-uptake by human tooth mineral during immersion into fluoride-containing aqueous solutions as different pH. Human teeth were immersed in fluoride-containing solutions to assess the extent of fluoride incorporation into tooth enamel. A total of 16 extracted teeth from 11 patients were immersed at 37 °C for one minute into aqueous fluoride solutions (potassium fluoride; KF) containing either 250 ppm or 18,998 ppm fluoride (1-molar). Fluoride was dissolved either in pure water (neutral pH) or in a citrate buffer (pH 4.6 to 4.7). The elemental surface composition of each tooth was studied by energy-dispersive X-ray spectroscopy in combination with scanning electron microscopy and X-ray powder diffraction. The as-received teeth contained 0.17 ± 0.16 wt% fluoride on average. There was no significant increase in the fluoride content after immersion in 250 ppm fluoride solution at neutral or acidic pH values. In contrast, a treatment with a 1-molar fluoride solution led to significantly increased fluoride concentrations by 0.68 wt% in water and 9.06 wt% at pH 4.7. Although such fluoride concentrations are far above those used in mouth rinses or toothpastes, this indicates that fluoride can indeed enter the tooth surface, especially at a low pH where a dynamic dissolution-reprecipitation process may occur. However, precipitations of calcium fluoride (globuli) were detected in no cases.

In Situ Formation of Copper Phosphate on Hydroxyapatite for Wastewater Treatment

Here, we control the surface activity of hydroxyapatite (HAp) in wastewater treatment which undergoes peroxodisulfate (PDS) activation. Loading the catalytically active Cu species on HAp forms a copper phosphate in the outer layer of HAp. This modification turns a low active HAp into a high catalytically active catalyst in the dye degradation process. The optimal operational conditions were established to be [Cu–THAp]₀ = 1 g/L, [RhB]₀ = 20 mg/L, [PDS]₀ = 7.5 mmol/L, and pH = 3. The experiments indicate that the simultaneous presence of Cu-THAp and PDS synergistically affect the degradation process. Additionally, chemical and structural characterizations proved the stability and effectiveness of Cu-THAp. Therefore, this work introduces a simple approach to water purification through green and sustainable HAp-based materials.

Hydroxyapatite as Remineralization Agent for Children's Dental Care

Children are prone to develop dental caries. This is supported by epidemiological data confirming early childhood caries (ECC) as a highly prevalent disease affecting more than every second child worldwide. ECC is known to result from an imbalance between re- and demineralization where demineralization dominates due to frequent acid production by cariogenic bacteria present in oral biofilms. The application of oral care formulations containing remineralizing agents helps to prevent dental caries. As young children are sensitive and usually swallow (intended or unintended) a majority of toothpaste or other oral care products during daily dental care, all ingredients, especially the actives, should be non-toxic. Biomimetic hydroxyapatite [HAP; Ca5(PO4)3(OH)] is known to have favorable remineralizing properties combined with an excellent biocompatibility, i.e., it is safe if accidently swallowed. Several clinical trials as well as in situ and in vitro studies have shown that HAP remineralizes enamel and dentin. Remineralization occurs due to deposition of HAP particles on tooth surfaces forming mineral-mineral bridges with enamel crystals, but also indirectly through calcium and phosphate ions release as well as HAP's buffering properties in acidic environments (i.e., in plaque). HAP induces a homogenous remineralization throughout the subsurface enamel lesions. This review summarizes the current evidence showing HAP as an effective remineralizing agent in oral care products for children. Additional studies showing also further beneficial effects of HAP such as the reduction of biofilm formation and the relief of hypersensitivity in children with molar incisor hypomineralization (MIH). It can be concluded that HAP is an effective and safe remineralizing agent for child dental care.