pH-cycling models for in vitro evaluation of the efficacy of fluoridated dentifrices for caries control: strengths and limitations

In Vitro Models Used in Cariology Mineralisation Research-A Review of the Literature

BACKGROUND

Dental caries remains a significant global health problem. One of the fundamental mechanisms underlying the development and progression of dental caries is the dynamic process of demineralisation/remineralisation. In vitro models have played a critical role in advancing our understanding of this process and identifying potential interventions to prevent or arrest dental caries. This literature review aims to provide a structured oversight of in vitro mineralisation models which have been used to study the tooth demineralisation/remineralisation process.

METHODS

Publications from 2019 to 2023 were screened to identify articles reporting the use of in vitro models to study the demineralisation/remineralisation of tooth caries. The included studies were methodologically assessed for their information on (i) substrate, (ii) lesion formation, and (iii) mineralisation models.

RESULTS

The most reported substrates used in the studies were human teeth along with bovine incisors. Acetic/lactic buffers were the most common solutions to induce caries lesions. pH cycling was the most frequently used mineralisation model for simulating the daily change within the oral environment. This review discussed the advantages and limitations of various approaches.

CONCLUSIONS

Standardisation of in vitro mineralisation models is crucial for enabling effective comparison between studies and advancing caries research.

Dual-species biofilm of Streptococcus mutans and Candida albicans produces subsurface caries lesions on bovine enamel

OBJECTIVES

To develop a protocol for forming subsurface caries lesions on bovine enamel by dual-species biofilms of Streptococcus mutans and Candida albicans in vitro.

DESIGN

Biofilms were grown on bovine enamel specimens in artificial saliva (AS) for seven days. After 24 h of formation, the AS was supplemented or not with fluoride (F) using sodium fluoride (0.005 or 0.008 ppm F), and the biofilms were exposed or not to a 20 % sucrose solution (reproducing a cariogenic challenge) once/day. On the seventh day, the biofilms were harvested and had their extracellular polysaccharides (EPS) and inorganic components analyzed. The specimens were subjected to computed X-ray microtomography analysis to determine their mineral concentration. Data were compared using two-way analyses of variance, followed by Fisher's LSD or Student-Newman-Keuls tests (p < 0.05).

RESULTS

Biofilms exposed to the cariogenic challenge had significantly higher EPS concentrations than those not exposed, regardless of the presence of F. For biofilms grown with 0.008 ppm F, those exposed to the cariogenic challenge had lower F levels than those not exposed. For biofilms exposed to the cariogenic challenge, those grown with 0.008 ppm F had lower lesion depths and integrated mineral loss, and higher outer layers than those grown without F.

CONCLUSIONS

The dual biofilm model assessed was able to create subsurface caries lesions in bovine enamel in vitro, which was influenced by the presence of F in the culture medium and exposure to sucrose.

Remineralizing effect of NSF on artificial enamel caries

INTRODUCTION

Nanotechnology offers new approaches and endless opportunities for remineralizing tooth decay without being toxic or causing allergies. This study aimed to determine the effect of nanosilver fluoride (NSF) on the remineralization potential of enamel caries-like lesions compared to 5% sodium fluoride varnish in permanent teeth.

METHODS

Fifteen teeth (molars and premolars) were gathered, cleaned, and polished using a scaler. After sectioning the teeth mesiodistally and removing the roots, the thirty specimens were subjected to a demineralized solution to induce early enamel lesions and then assigned randomly into two equal groups. The test materials were applied, and then all the specimens were subjected to a pH cycling model for 30 days. DIAGNOdent and surface roughness were investigated, and an evaluation of the enamel Ca and P weight% for Ca/P ratio calculation was done using SEM-EDX to analyze the specimens at the end of the study. The data were analyzed using an independent t-test.

RESULTS

The mean values for the DIAGNOdent measurements for NSF and NaF at baseline and after demineralization were not significantly different (p > 0.05). After treatment, NaF varnish showed a significantly higher mean DIAGNOdent measurement (11.8 ± 5.80) than NSF (4.7 ± 1.6). The mean surface roughness of the NaF group (1.64 ± 0.39) was much higher than NSF's mean surface roughness (1.07 ± 0.21). Specimens treated with NSF had statistically significant smoother surfaces (p < 0.001). The NSF group had a higher mean Ca/P ratio (2.9 ± 0.35) than NaF (2.2 ± 0.11). This difference was statistically significant (p = 0.012).

CONCLUSION

The study reveals that nano silver fluoride is a more effective treatment than sodium fluoride varnish in enhancing teeth's clinical characteristics, particularly in terms of mineral content and surface roughness, suggesting it could be an improved strategy to prevent dental caries and maintain enamel integrity.

Remineralization potential of apacider gel on enamel and cementum surrounding margin of ceramic restoration

Background

Modern management of carious lesions has been targeted upon using remineralizing agents. This study investigated the remineralization potential of apacider gel (AG) and casein phosphopeptide-amorphous calcium fluoride phosphate (CA) on enamel and cementum around the cavosurface area of the ceramic margin.

Material and Methods

Seventy-five extracted human mandibular molars were sectioned at 0.8 mm above and below the cemento-enamel junction (CEJ) to remove the CEJ portions and replaced them with glass ceramic disks by bonding them to the crown and root portions with resin cement. The enamel and cementum area of 4x4 mm2 surrounding ceramic was demineralized with Carbopol-907. The demineralized surfaces were treated with either AG or CA, while one group was left with no treatment (NT) and served as control. Vickers microhardness was determined before-, after demineralization, and after remineralization. The percentage of hardness recovery (%HR), and remineralization potential (%RP) were analyzed with ANOVA and Bonferroni's test (α=0.05). Polarized light microscopy (PLM) was assessed for lesion depth. Scanning electron microscopy (SEM) was investigated for surface alterations.

Results

Significant differences in remineralization were found upon various remineralizing agents compared to NT for both enamel and cementum (p<0.05). No significant difference in %HR and %RP was observed between AG and CA (p>0.05). However, AG signified greater decrease in lesion depth and better improvement in surface characteristics for both enamel and cementum than CA.

Conclusions

AG possesses comparable remineralization ability to CA. However, decreasing in carious lesion depth was evinced with using AG more than CA. AG was recommended as a potential remineralization material for handling initial caries for both enamel and cementum. Key words:Apacider, artificial carious lesion, CCP-ACFP, remineralizationCare Team.

Resin tags formation by modified Renewal MI formulations in a carious dentine model

Objectives

To determine which components in a new restorative material (Renewal MI) improve its ability to form resin tags within demineralized dentine.

Methods

Varied components included polylysine (PLS), monocalcium phosphate (MCP), powder to liquid ratio (PLR), 4-methacryloyloxyethyl trimellitate anhydride (4META), and polypropylene glycol dimethacrylate (PPGDMA). Urethane dimethacrylate (UDMA), containing PPGDMA (24 wt%) and 4META (3 wt%), was mixed with glass filler with MCP (8 wt%) and PLS (5 wt%). PLR was 3:1 or 5:1. Reducing MCP and/or PLS to 4 and 2 wt% respectively or fully removing MCP, PLS, 4META or PPGDMA gave 16 formulations in total. Renewal MI, Z250 (with or without Scotchbond Universal adhesive) and Activa were used as commercial comparators. Collagen discs were obtained by totally demineralizing 2 mm thick, human, premolar, coronal dentine discs by immersion in formic acid (4M) for 48 h. The restorative materials were then applied on top (n = 3), before dissolving the collagen in sodium hypochlorite (15%). SEM/EDX was employed to determine resin tags length, composition, and surface coverage.

Results

Tags were >400, 20 and 200 µm and covered 62, 55 and 39% of the adhesion interface for Renewal MI, Scotchbond and Activa, respectively. With experimental formulations, they were 200 and >400 µm long with high vs. low PLR and composed primarily of polymerized monomers. Percentages of the adhesion interface covered varied between 35 and 84%. Reducing PLS or MCP caused a decline in coverage that was linear with their concentrations. Reducing MCP had lesser effect when PLS or PLR were low. Removal of 4META caused a greater reduction in coverage than PPGDMA removal.

Conclusion

PLS, MCP, 4META, PPGDMA and low PLR together enhance Renewal MI tags formation in, and thereby sealing of, demineralized dentine.

Biomimetic Remineralization of Artificial Caries Lesions with a Calcium Coacervate, Its Components and Self-Assembling Peptide P11-4 In Vitro

The application of calcium coacervates (CCs) may hold promise for dental hard tissue remineralization. The aim of this study was to evaluate the effect of the infiltration of artificial enamel lesions with a CC and its single components including polyacrylic acid (PAA) compared to that of the self-assembling peptide P11-4 in a pH-cycling (pHC) model. Enamel specimens were prepared from bovine incisors, partly varnished, and stored in demineralizing solution (DS; pH 4.95; 17 d) to create two enamel lesions per sample. The specimens were randomly allocated to six groups (n = 15). While one lesion per specimen served as the no-treatment control (NTC), another lesion (treatment, T) was etched (H3PO4, 5 s), air-dried and subsequently infiltrated for 10 min with either a CC (10 mg/mL PAA, 50 mM CaCl2 (Ca) and 1 M K2HPO4 (PO4)) (groups CC and CC + DS) or its components PAA, Ca or PO4. As a commercial control, the self-assembling peptide P11-4 (CurodontTM Repair, Credentis, Switzerland) was tested. The specimens were cut perpendicularly to the lesions, with half serving as the baseline (BL) while the other half was exposed to either a demineralization solution for 20 d (pH 4.95; group CC + DS) or pHC for 28 d (pH 4.95, 3 h; pH 7, 21 h; all five of the other groups). The difference in integrated mineral loss between the lesions at BL and after the DS or pHC, respectively, was analyzed using transversal microradiography (ΔΔZ = ΔZpHC - ΔZbaseline). Compared to the NTC, the mineral gain in the T group was significantly higher in the CC + DS, CC and PAA (p < 0.05, Wilcoxon). In all of the other groups, no significant differences between treated and untreated lesions were detected (p > 0.05). Infiltration with the CC and PAA resulted in a consistent mineral gain throughout the lesion body. The CC as well as its component PAA alone promoted the remineralization of artificial caries lesions in the tested pHC model. Infiltration with PAA further resulted in mineral gain in deeper areas of the lesion body.

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

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

Remineralization potential of dentifrices with calcium sodium phosphosilicate and functionalized tri-calcium phosphate in the deeper incipient carious lesions: An in vitro study

OBJECTIVES

This study evaluated the remineralization potential of calcium sodium phosphosilicate and functionalized tri-calcium phosphate (f-TCP) dentifrices in deeper incipient carious lesions (ICLs).

MATERIALS AND METHODS

Artificial ICLs were created by placing premolars into demineralizing solutions. Teeth were randomly assigned into four groups: calcium sodium phosphosilicate (Group 1), f-TCP (Group 2), 1450 ppm fluoride (Group 3), and distilled water (Group 4), which were subjected to 10-day pH cycling. Mineral density (MD) was assessed using microcomputed tomography (Micro-CT), while hardness (H) and elastic modulus (EM) were assessed using nanomechanical testing.

RESULTS

MD % gain was higher in Groups 1-3 than in Group 4. In addition, Groups 1 and 2 exhibited significantly higher MD % gain than Group 3. Also, Groups 1-3 showed significantly higher EM and H values than Group 4 in the outer enamel area; yet, Groups 1 and 2 displayed significantly higher EM and H values than Groups 3 and 4 in the inner enamel.

CONCLUSIONS

The MD, EM, and H of ICLs significantly increased with the addition of calcium sodium phosphosilicate or f-TCP to fluoridated dentifrices compared to standard fluoride dentifrices. The added active ingredients remineralized the deeper parts of the ICLs, while remineralization at the lesion surface was similar between tested dentifrices.

Remineralization potential of apacider mangosteen adhesive pastes on artificial carious lesions

Background/purpose

Attention to caries administration has altered toward an early finding of lesions and targeted to noninvasive management with a remineralizing agent. This study compared the remineralization potential of apacider mangosteen adhesive pastes (AMAP), 500-ppm fluoride toothpaste (FT500), and 1000-ppm fluoride toothpaste (FT1000) on artificial caries.

Materials and methods

Artificial caries were generated to enamel of eighty extracted human premolars. The specimens were allocated to four groups and subjected to pH-cycling with the application of testing agents (2 min each, for 10 days): (1) AMAP, dairy, (2) FT500, twice a day, (3) FT1000, twice a day, and (4) no treatment (NT). The surface microhardness was determined before demineralization, after demineralization, and after application of pH-cycling. The hardness, percent of hardness recovery (%HR), and percent of remineralization potential (%RP) were analyzed with ANOVA and Bonferroni's test (α = 0.05). Polarized light microscopy (PLM) was assessed for lesion depth.

Results

Significant differences in remineralization were observed upon various agents compared to NT (P < 0.05). A significant difference in remineralization was found among AMAP, FT1000, and FT500 (P < 0.05). No significant difference in %HR and %RP was observed between AMAP and FT1000 (P > 0.05). PLM signified greater decrease in depth for AMAP, compared to FT1000 and FT500, but no depth reduction for NT.

Conclusion

AMAP possesses comparable remineralization ability to FT1000. However, decreasing in depth of carious lesions was evinced with using AMAP more than FT1000 and FT500. AMAP was recommended as a potential remineralization material for handling initial caries.

In vitro remineralization by various ion-releasing materials of artificially demineralized dentin: A micro-CT study

OBJECTIVE

The aim of this study was to evaluate the remineralizing properties of ion-releasing restorative materials on pH cycling-induced carious dentin.

METHODS

Fifty sound molars were freshly extracted. The occlusal surfaces were abraded using water-cooled sandpaper (800 grit). The residual crowns were embedded in self-cured acrylic resin with the flat dentin surface exposed. A mesio-distal trench was created using a calibrated 0.5 mm deep occlusal reduction burr, and artificial dentin caries were generated by pH cycling. Then, teeth were randomly assigned to five groups according to the ion-releasing material used. For each sample, micro-CT acquisitions were performed at various intervals. Remineralization was assessed by mean gray value (MGV) measurements after registration and segmentation of the region of interest with 3D Slicer software. One-way repeated-measures ANOVA followed by Tukey's post hoc test was used to investigate the difference in MGVs among the various groups.

RESULTS

Only Cention Forte showed significantly increased MGVs after 4 weeks compared to demineralized dentin. MGVs were higher, but not significantly, after placement of the restorative materials, including in the resin composite control group. These results can be explained by the radiopacity of the materials.

SIGNIFICANCE

Cention Forte, the material with the highest radiopacity, showed a significant increase in the MGVs of artificially carious dentin after 4 weeks. However, the study of dentin remineralization by micro-CT could be impacted by the radiopacity of the restorative materials used. The relevance of this examination for the study of dentinal remineralization should be investigated.

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

Aim

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

Materials and Methods

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

Results

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

Conclusion

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

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.

Multidisciplinary evaluation of the remineralization potential of three fluoride-based toothpastes on natural white spot lesions

OBJECTIVES

This in vitro study aimed assessing the remineralization potential of three commercial fluoride-based toothpastes in permanent teeth with natural white spot lesions (WSLs). A multidisciplinary approach based on Raman microspectroscopy (RMS), Scanning electron microscopy (SEM), Energy-dispersive x-ray spectroscopy (EDS), and Vickers microhardness (VMH) was exploited.

METHODS

N = 12 human molars with natural WSLs in the proximal-vestibular zone were selected and divided into 4 groups (n = 3) according to the different treatments: HAF (hydroxyapatite with fluoride ions); SMF (sodium monofluorophosphate with arginine); SF (sodium fluoride with enzymes), and CTRL (untreated group). All toothpastes tested contained 1450 ppm of fluoride. Teeth samples were submitted to the following protocol: a 7-day pH cycling treatment, with two daily exposures (2 min each time) to the commercial toothpastes described above. The surface micromorphology (SEM), the chemical/elemental composition (RMS and EDS), and the Vickers microhardness (VMH) were evaluated. Statistical analysis was performed.

RESULTS

A remarkable remineralization of WSLs in SEM images was observed in all treated groups compared to CTRL. In particular, HAF and SF displayed higher values of VMH, phosphates amount (I960), crystallinity (FWHM960), and lower ones of C/P (I1070/I960) with respect to CTRL. Intermediate values were found in SMF, higher than CTRL but lower with respect to HAF and SF. As regards the Ca/P ratio, statistically significant differences (p < 0.05) were found between SF and the other groups.

CONCLUSIONS

All the tested dentifrices have shown to remineralize the WSLs. SF and HAF have comparable capability in hardness recovery and crystallinity; however, SF shows the best remineralizing potential according to both micromorphological and chemical analyses. Clinical relevance The daily use of toothpastes containing hydroxyapatite partially replaced with fluoride, sodium monofluorophosphate with arginine and sodium fluoride toothpaste associated with enzymes represents a preventive, therapeutic, effective, and non-invasive tool for remineralize WSLs.

Development of a Novel Peptide with Antimicrobial and Mineralising Properties for Caries Management

The purpose of the study is to develop a novel peptide for caries management. Gallic-Acid-Polyphemusin-I (GAPI) was synthesised by grafting Polyphemusin I (PI) and gallic acid (GA). Biocompatibility was evaluated using a Cell Counting Kit-8 Assay. Antimicrobial properties were assessed using minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC). The bacterial and fungal morphology after GAPI treatment was investigated using transmission electron microscopy (TEM). The architecture of a consortium biofilm consisting of Streptococcus mutans, Lacticaseibacillus casei and Candida albicans was evaluated using scanning electron microscopy (SEM) and confocal laser scanning microscopy. The growth kinetics of the biofilm was examined using a propidium monoazide-quantitative polymerase chain reaction. The surface and calcium-to-phosphorus molar ratio of GAPI-treated enamel after pH cycling were examined with SEM and energy-dispersive X-ray spectroscopy. Enamel crystal characteristics were analysed using X-ray diffraction. Lesion depths representing the enamel's mineral loss were assessed using micro-computed tomography. The MIC of GAPI against S. mutans, L. casei and C. albicans were 40 μM, 40 μM and 20 μM, respectively. GAPI destroyed the biofilm's three-dimensional structure and inhibited the growth of the biofilm. SEM showed that enamel treated with GAPI had a relatively smooth surface compared to that treated with water. The calcium-to-phosphorus molar ratio of enamel treated with GAPI was higher than that of the control. The lesion depths and mineral loss of the GAPI-treated enamel were less than the control. The crystallinity of the GAPI-treated enamel was higher than the control. This study developed a biocompatible, mineralising and antimicrobial peptide GAPI, which may have potential as an anti-caries agent.

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.

The Role of Bacterial, Dentinal, Salivary, and Neutrophil Degradative Activity in Caries Pathogenesis

Until recently, it was widely accepted that bacteria participate in caries pathogenesis mainly through carbohydrate fermentation and acid production, which promote the dissolution of tooth components. Neutrophils, on the other hand, were considered white blood cells with no role in caries pathogenesis. Nevertheless, current literature suggests that both bacteria and neutrophils, among other factors, possess direct degradative activity towards both dentinal collagen type-1 and/or methacrylate resin-based restoratives and adhesives, the most common dental restoratives. Neutrophils are abundant leukocytes in the gingival sulcus, where they can readily reach adjacent tooth roots or gingival and cervical restorations and execute their degradative activity. In this review, we present the latest literature evidence for bacterial, dentinal, salivary, and neutrophil degradative action that may induce primary caries, secondary caries, and restoration failure.

Assessment of enamel surface roughness and hardness with metal and ceramic orthodontic brackets using different etching and adhesive systems: An in vitro study

Background

This study aimed to evaluate enamel surface roughness and microhardness following the use of different bracket materials (metal or ceramic), etchants (total- and self-etchants), and adhesive systems (precoated or flash-free).

Method

A total of 99 extracted human premolars were selected for the analysis. The surface roughness was first assessed (roughness control). One specimen from each subgroup was examined using a scanning electron microscope to illustrate the surface topography. Eighty-eight teeth were prepared using total- or self-etchants and bonded to precoated or flash-free adhesive metal or ceramic brackets. The remaining 11 specimens were not bonded to brackets (microhardness controls). The brackets were debonded after immersion in distilled water for 24 h. The specimens were again scanned for surface roughness and topography imaging. Finally, the microhardness was assessed using a micro-Vickers hardness test at a force of 200 g for 10 s.

Result

An overall statistically significant increase in surface roughness and reduced surface microhardness were observed in all experimental groups when compared with those in the control groups. The etchant type was the only variable found to contribute to the measured surface properties, with increased roughness and reduced microhardness introduced by total-etching compared to those by self-etching.

Conclusion

Orthodontic brackets introduced a significant increase in enamel surface roughness and reduce microhardness compared with untreated enamel, regardless of the bracket material, etchant type, and adhesive system. The etchant type was the only variable contributing to these changes, with total etching having a more pronounced effect.

Enamel Remineralization Efficacy of Coconut Milk and Lyophilized Coconut Extract in Different Concentrations on Demineralized Enamel Surfaces: An In-Vitro Study

Aim The current study's objective is to determine the remineralizing efficacy of freeze-dried lyophilized coconut extract and coconut milk made from freshly grated coconut on artificial carious lesions produced by pH cycling. Materials and methods Freshly extracted coconut pulp was split into two parts. The first half was blended to obtain coconut milk, and the second part was freeze-dried and lyophilized. Tooth slabs were prepared from extracted third molar teeth. After being demineralized for 72 hours, the tooth samples were remineralized by submerging them in the appropriate remineralizing solution, which is as follows: Group 1 received 25 mL of the Remineralization solution (the control); Group 2 received 2.5 g of coconut milk and 25 mL of the solution (1:1); and Group 3 received 5 g of coconut milk and 25 mL of the solution (2:1). 2.5 g of freeze-dried, lyophilized coconut extract was given to Group 4 along with 25 mL of remineralization solution (1:1), and 5 g of freeze-dried, lyophilized coconut extract was given to Group 5 along with 25 mL of remineralization solution (2:1). Microhardness and contact angle measurements were made. An Excel spreadsheet was filled up with values from after demineralization, and after remineralization. A statistical analysis was performed using SPSS 26.0 (IBM Corp., Armonk, NY). Using descriptive statistics, the pretreatment mean values for the microhardness and contact angle of the various groups were evaluated. Post-hoc Tukey tests were utilized to compare the analytic results of the various groups. Results Among the various concentrations of freshly extracted coconut milk, the contact angle in concentrations of 1:1 was 81.22 ± 1.62 deg, and that in concentrations of 2:1 was 88.01 ± 1.85 deg. Between the two concentrations of the lyophilized coconut extract group, the contact angle in 1:1 was 75.05 ± 2.29 deg, and in 2:1 was 71.37 ± 0.85 deg. In the coconut milk group, the value of microhardness was 261 ± 6.4 kg/cm2 at a lower concentration and 322 ± 3.9 kg/cm2 at a higher concentration. In the lyophilized coconut group, the lower concentration exhibited a microhardness of 211 ± 7.2 kg/cm2, whereas in the higher concentration, it was 324 ± 4.04 kg/cm2. Conclusion Of the various concentrations of coconut milk and lyophilized coconut used, coconut milk at a higher concentration exhibits the highest contact angle, and the latter at a higher concentration exhibits the lowest contact angle. In both groups, high concentrations of the material exhibited high microhardness values compared to lower concentrations of the same.

Recurrent caries models to assess dental restorations: A scoping review

OBJECTIVES

To review the literature on recurrent caries models used to evaluate restorative materials, compare reported methodology and parameters, and devise specific recommendations to be considered in future investigations.

DATA

The following were extracted: study design, sample characteristics, source of teeth, name of restorations compared including controls, recurrent caries model type, type of demineralizing and remineralizing solutions, type of biofilm used, methods to detect recurrent caries.

SOURCES

Literature searches were performed in OVID Medline, EMBASE, SCOPUS, and Cochrane Library.

STUDY SELECTION

For a study to be included, it had to examine dental materials for tooth restoration purposes only with a valid control group and evaluate restorative dental materials regardless of the form of the teeth caries model used or nature of the tooth structure used. A total of 91 studies were included. Most of the studies presented were in vitro. Human teeth were the main source of specimens utilized. Around 88% of the studies used specimens without an artificial gap, and 44% used a chemical model. S. mutans was the main bacterial species used in microbial caries models.

CONCLUSION

The findings of this review provided an insight into the performance of available dental materials assessed using different recurrent caries models, yet this review cannot be used as a guideline for material selection. Selecting the appropriate restorative material relies on several patient-related factors such as microbiota, occlusion, and diet that are not comprehensively taken into consideration in recurrent caries models and thus hinder reliable comparison.

CLINICAL SIGNIFICANCE

Due to the heterogenicity of variables among studies on the performance of dental restorative materials, this scoping review aimed to provide insights for dental researchers concerning the available recurrent caries models, testing methods used, and aspects of comparison between these materials including their characteristics and limitations.

Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study

Introduction

With the paradigm shift in the management of dental caries, the focus is now laid on remineralization therapies that can arrest the progression of the disease and remineralize the subsurface lesions.

Objectives

The purpose of this study was to determine and compare the remineralizing potential of silver diamine fluoride (SDF), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and fluoride varnish (FV) on enamel surfaces in primary and permanent teeth.

Materials and methods

A total of 120 primary anterior teeth and 120 premolars were used to prepare enamel blocks in acrylic resin. The mean baseline surface microhardness (SMH) for each sample was determined using a microvickers hardness testing machine. Thereafter, the samples were randomly and equally distributed into groups and subgroups based on the materials used, that is, SDF, CPP-ACP, FV, and distilled water (control). After subjecting the samples to a pH cycling regime, SMH was determined again and the percentage change in SMH was calculated.

Results

The data were tabulated and subjected to statistical analysis using an independent t-test and one-way analysis of variance (ANOVA). In primary teeth, the least mean percentage reduction in SMH was observed after the application of FV followed by SDF, CPP-ACP, and control. In permanent teeth, both SDF and FV showed the least percentage reduction of enamel SMH followed by CPP-ACP and control.

Conclusion

Silver diamine fluoride (SDF), FV, and CPP-ACP showed remineralizing potential in both primary and permanent teeth.

How to cite this article

Kaur S, Bhola M, Bajaj N, et al. Comparative Evaluation of the Remineralizing Potential of Silver Diamine Fluoride, Casein Phosphopeptide-amorphous Calcium Phosphate, and Fluoride Varnish on the Enamel Surface of Primary and Permanent Teeth: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S91-S96.

Effect of polydopamine and fluoride ion coating on dental enamel remineralization: an in vitro study

BACKGROUND

Fluoride treatment is one of the most effective dental caries prevention methods. To continuously prevent dental caries, stably immobilizing the fluoride on the tooth enamel is highly desirable. This study aimed to evaluate the remineralization of tooth enamels by one-pot coating using polydopamine and fluoride ions.

METHODS

To prepare the enamel specimens for polydopamine- and fluoride ion-coating, they were treated with polydopamine- and fluoride-containing gels. The enamel specimens were collected from human molars in a blind manner (n = 100) and were randomized into five treatment groups (n = 20, each): 1) untreated, 2) polydopamine-coated, 3) fluoride-containing gel-treated, 4) F varnish-treated, and 5) polydopamine- and fluoride ion-coated enamels. Vickers hardness number (VHN), morphology, and fluoride contents of the specimens were measured before and after the pH-cycling regimen.

RESULTS

Polydopamine- and fluoride ion-coated enamels showed the highest fluoride content and lowest VHN reduction among the samples. The fluoride content of the polydopamine/fluoride ion (PD/F)-coated enamel was increased to 182 ± 6.6%, which was far higher than that of the uncoated enamel (112.3 ± 32.8%, P < 0.05). The changes in the VHN values (ΔVHN) of PD/F-coated enamel substrates showed a slight reduction in the VHN (-3.6%, P < 0.05), which was far lower than that in the control group (-18.9%, P < 0.05). In addition, scanning electron microscopy clearly supported the effect of polydopamine- and fluoride ion-coatings on the remineralization of enamel specimens.

CONCLUSION

Our findings suggest that one-pot treatments with polydopamine and fluoride ions could significantly enhance remineralization by inhibiting enamel demineralization through the prolonged retention of fluoride ions.

Effect of N-Acetylcysteine on initial Carious Enamel Lesions in primary teeth: an In-vitro study

BACKGROUND

Dental caries initiates with non-cavitated enamel lesions as the first stage. The cariogenic potential of N-Acetylcysteine (NAC) may be due to its usage frequency and form. This study aimed to evaluate the impact of exposure time of NAC on initial enamel caries-like lesions in primary teeth by assessing the morphological alteration using a scanning electron microscope (SEM) and mineral content using energy dispersive x-ray spectroscopy (EDX).

METHODS

Forty primary incisor teeth were randomly divided into 4 groups S, S1, S2, and S3 (10 specimens/group). Teeth crowns were cut from their roots and inserted into an acrylic mold with its buccal surface directed upward. Centrally isolated enamel window (2 × 2 mm) on the tooth was done. Ten specimens were selected to evaluate normal enamel while the remaining thirty specimens were immersed in demineralizing solution for 96 h to produce enamel caries-like lesions. PH cycling was performed by immersing each tooth sample in 20 mL of demineralizing solution for 3 h then, preserved for the remaining day hours in 10 ml of artificial saliva interspersed with treatments applications with 10 ml NAC for 10 min twice a day for one- or three-months different treatment modalities. Thermocycling was done for all specimens then they were subjected to SEM and EDX analysis. ANOVA and Bonferroni post hoc tests were utilized in data analysis.

RESULTS

In teeth treated by NAC for 3 months (group-S3), SEM images showed severe loss of enamel architecture with large NAC deposits detected. A meaningful difference was observed among different groups concerning calcium, phosphorus, fluoride, ca/P ratio, carbon, nitrogen, and oxygen contents (P < 0.05).

CONCLUSION

NAC had a detrimental impact on enamel caries-like lesions in human primary teeth.

Fully Automated Bioreactor-Based pH-Cycling System for Demineralization: A Comparative Study with a Conventional Method

This study aimed to develop an automated pH-cycling system using inexpensive commercial components that can replicate pH fluctuations in the oral cavity and salivary clearance to compare demineralization characteristics with the conventional method. The study found that the newly developed cycle-1 group showed improved demineralization properties, including apparent lesion depth, surface roughness, Vickers hardness, mineral loss, and depth of demineralization, compared to the control group. Additionally, the cycle-2 group, which had a longer cycle interval, showed further improvements in the demineralization properties. This system can replicate the differences in dental damage caused by differences in meals, snacking frequencies, and lifestyle rhythms, making it useful in cariology, preventive dentistry research, and oral care product development. It can be constructed using inexpensive commercial products, significantly reducing research costs and improving reproducibility and fairness between different experimental facilities. The system can replicate lifestyle rhythms, such as meals, sleep, and oral clearance by saliva, making it an in vitro pseudo-oral cavity.

Efficacy of Nano Silver Fluoride and/or Diode Laser In Enhancing Enamel Anticariogenicity around orthodontic brackets

PURPOSE

This in vitro study aimed to compare the anticariogenic effect of using diode laser irradiation and/or nano silver fluoride varnish around orthodontic brackets.

MATERIALS AND METHODS

60 caries-free and intact premolars were randomly divided into 3 experimental groups as follow: (1) Group I (nano silver fluoride treated group, n = 20), (2) Group II (diode laser treated group, n = 20) and (3) Group III (combined nano silver fluoride and diode laser treated group, n = 20). Anticariogenicity was assessed using polarized light, scanning electron microscope, elemental and shear bond strength analyses.

RESULTS

PLM and SEM showed presence of few demineralized areas in group I. Group II revealed a dramatic increased demineralization. Group III disclosed almost typical homogenous surface enamel. elemental analysis showed a highly significant difference between Group III and II and a significant difference between Group III and I. Shear bond strength analysis revealed a significant difference between group I and II and between group III and II. The difference between group III and I was non-significant.

CONCLUSION

Both diode laser and nano silver fluoride positively affected dental enamel with the most superior enhancement in enamel criteria was achieved by surface pretreatment by combined nano silver fluoride varnish and diode laser irradiation.

Engineered Peptides Enable Biomimetic Route for Collagen Intrafibrillar Mineralization

Overcoming the short lifespan of current dental adhesives remains a significant clinical need. Adhesives rely on formation of the hybrid layer to adhere to dentin and penetrate within collagen fibrils. However, the ability of adhesives to achieve complete enclosure of demineralized collagen fibrils is recognized as currently unattainable. We developed a peptide-based approach enabling collagen intrafibrillar mineralization and tested our hypothesis on a type-I collagen-based platform. Peptide design incorporated collagen-binding and remineralization-mediating properties using the domain structure conservation approach. The structural changes from representative members of different peptide clusters were generated for each functional domain. Common signatures associated with secondary structure features and the related changes in the functional domain were investigated by attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and circular dichroism (CD) spectroscopy, respectively. Assembly and remineralization properties of the peptides on the collagen platforms were studied using atomic force microscopy (AFM). Mechanical properties of the collagen fibrils remineralized by the peptide assemblies was studied using PeakForce-Quantitative Nanomechanics (PF-QNM)-AFM. The engineered peptide was demonstrated to offer a promising route for collagen intrafibrillar remineralization. This approach offers a collagen platform to develop multifunctional strategies that combine different bioactive peptides, polymerizable peptide monomers, and adhesive formulations as steps towards improving the long-term prospects of composite resins.

Remineralization effects of Er,Cr:YSGG and/or bioactive glass on human enamel after radiotherapy-an in vitro study

The aim was to evaluate the effects of Er,Cr:YSGG and/or bioactive glass 45S5 (BG) on the chemical and physical properties of enamel after radiotherapy. Third molar crowns were cut in half (buccal-lingually), and the mid part of the labial/oral surface was subjected to different protocols. All samples were treated with standard 70 Gy. After radiotherapy, enamel was treated with either Er,Cr:YSGG (2780 nm; pulse 60 μs) and BG or only BG, and control samples were kept in deionized water. Vickers microhardness, scanning electron microscopy (SEM), and characteristic X-ray spectroscopy (EDS) were performed before, after radiotherapy, and after treatment. Analysis of variance (ANOVA) was used. A significant drop in enamel microhardness was observed after radiotherapy (p < 0.001). After Er,Cr:YSGG and BG or BG alone, there was a significant increase in microhardness (p < 0.001), which was on average significantly higher compared to the initial measurements for Er,Cr:YSGG with BG (p < 0.001), but not observed in BG alone (p = 0.331). After radiotherapy, SEM showed increased surface roughness with eroded prisms. Er,Cr:YSGG and BG or BG alone both showed disorderly packed glass particles on the enamel surface. Radiotherapy noticeably reduced the concentrations of calcium and phosphorus. Er,Cr:YSGG and BG treatment increased the concentrations of calcium, sodium, phosphorus, and silicate. BG treatment alone increased the concetration of calcium and phosphorus. Directly induced radiotherapy led to potential damage of enamel, but afterwards treatment with Er,Cr:YSGG laser and BG resulted in a higher increase of enamel microhardness compared to BG alone, reflecting in a possible better remineralization effect.

Evaluation of different remineralization agents in the treatment of natural caries-affected dentin in permanent teeth

BACKGROUND

In the preventive treatment protocol, providing remineralization of the tissue in demineralized dentin caries is an important step.

OBJECTIVE

In this in vitro study, the effectiveness of remineralization agents in natural caries-affected dentin (NCAD) were investigated.

METHODS

Forty caries slices were prepared from permanent molar dentin with International Caries Detection and Assessment System (ICDAS 2) (Code 3). The interventions with 8 days pH cycling were as follows: Deionized water (DW); 5% Sodium Fluoride (5% NaF) Varnish; Casein Phosphopeptide-Amorphous Calcium Fluoride Phosphate (CPP-ACFP); Calcium Glyserophosphate (CaGP) + Magnesium (Mg) + Xylitol. DIAGNOdent (Laser Fluorescence, LF), Surface Microhardness (SMH), and X-ray Fluorescence (XRF) Spectroscopy measurements were calculated before and after pH cycling.

RESULTS

LF values decreased between 5% NaF, CCP-ACFP and CaGP. NCAD treated with 5% NaF, CaGP and CCP-ACFP exhibited statistically higher hardness compared to the control group. After 5% NaF application, SMH values were significantly higher than the others. There was no statistically significant difference between baseline and after pH cycling hardness of the control group. After cycling, XRF showed that Ca and P concentrations were increased in all groups.

CONCLUSION

The application of agents used in the study could be recommended and promoted as a treatment option of caries dentin for conventional management of caries.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions

OBJECTIVE

(1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces.

METHODOLOGY

In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests.

RESULTS

Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02).

CONCLUSIONS

The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Effect of a bioactive pit and fissure sealant on demineralized human enamel: in vitro study

BACKGROUND

Incorporation of bioactive agent into pit and fissure sealant would halt demineralization and promote further remineralization. The aim was to assess the effect of bioactive and fluoride fissure sealants on calcium and phosphate content and surface topography of artificially demineralized enamel in young permanent teeth.

METHODS

30 sound extracted premolars free from cracks or any developmental anomalies were used. They were divided into group I bioactive fissure sealant, group II fluoride fissure sealant and group III no material applied. Each tooth was divided into halves in a buccolingual direction and evaluated by energy dispersive X-ray spectrometer (EDX) at baseline, demineralization and after applying the material. Another set of 7 sound extracted premolars was evaluated by scanning electron microscopy (SEM) at the same phases.

RESULTS

EDX showed that regaining calcium to demineralized enamel was significantly higher with bioactive sealant than either fluoride or the control group. SEM revealed minerals deposits with formation of distinct white zone at tooth/sealant interface for both pit and fissure sealant groups. Whereas no white zone formation was detected in control group.

CONCLUSIONS

Incorporating bioactive material into pit and fissure sealant through microcapsules provided better results than incorporating fluoride by enhancing the biological process of remineralization.

CLINICAL RELEVANCE

The more use of bioactive pit and fissure sealant would maintain the occlusal surfaces as sound structures and decrease the need for operative procedures to restore teeth cavitation.

Assessment of the Remineralizing Efficacy of Grape Seed Extract vs Sodium Fluoride on Surface and Subsurface Enamel Lesions: An In Vitro Study

AIM

The aim of this study was to evaluate the efficacy of grape seed extract (GSE) on remineralization of surface and subsurface enamel lesions compared to that of sodium fluoride (NaF).

MATERIALS AND METHODS

A total of 20 intact bovine incisor crowns were separated from their roots and immersed in a demineralizing solution for 96 hours at 37°C to create artificial enamel lesions. The specimens were randomly divided into two groups (n = 10): 6.5% GSE solution and 1000 ppm NaF solution. The specimens were subjected to six daily pH cycles for 8 days. The microhardness test was carried out at three different stages: baseline, after artificial caries formation, and after pH cycling. Raman spectroscopy was used to evaluate the depth of enamel remineralization. Surface morphology and elemental analysis were assessed using a scanning electron microscope (SEM) and an energy dispersive X-ray (EDX) spectroscope, respectively. Statistical analysis was performed using SPSS 22.0 at a significance level of p ≤ 0.05.

RESULTS

There was a significant increase in the mean values of enamel surface microhardness after pH cycles in the two groups compared to after artificial caries formation, but there was no significant difference between both groups. The B-type carbonate/phosphate (Ca/P) ratio at 10 and 40 µm depth revealed no significant difference between the two groups. Scanning electron microscope micrograph revealed occlusion of porosities and particle precipitation on the enamel surface of the two groups, while EDX results for the Ca/P ratio of the GSE and NaF groups were 1.59 and 1.60, respectively.

CONCLUSION

Grape seed extract and NaF are equally effective in remineralizing surface and subsurface artificial enamel lesions.

CLINICAL SIGNIFICANCE

Grape seed extract can be considered a promising herbal material and a safe alternative to traditional NaF for the noninvasive treatment of enamel lesions.

Effect of different surface treatments on the microhardness and colour change of artificial enamel lesions

BACKGROUND

To investigate the effect of three different surface treatments on the microhardness and colour change of artificial enamel lesions.

MATERIALS AND METHODS

One hundred bovine teeth were randomly assigned into four groups. Artificial enamel lesions were created using demineralizing solution for all groups except the sound enamel group. Different surface treatments were then performed G1: resin-infiltrant; G2: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP); G3: artificial saliva; G4: Sound Enamel. Each group was subdivided into three subgroups, where each subgroup was subjected to a different testing method. Subgroup 1: surface microhardness; subgroup 2: cross-sectional microhardness; subgroup 3: colour measurement. Statistical analysis was performed by ANOVA, followed by Tukey's post hoc test.

RESULTS

Sound enamel group recorded the highest surface and cross-sectional microhardness results. No significant difference was found between the resin-infiltrant group and CPP-ACP regarding surface and cross-sectional microhardness at different lesion depths. Resin-infiltrant group showed the least colour change (∆E) results compared to the other groups.

CONCLUSION

Resin-infiltrant can effectively enhance surface microhardness and enamel resistance to demineralization, additionally, reduces the staining susceptibility of white spot lesions (WSLs) after treatment. CPP-ACP application for 4 weeks seems to improve surface microhardness; however, has a limited effect in resisting staining of WSLs after treatment. © 2022 Australian Dental Association.

Preventive potential of nano silver fluoride versus sodium fluoride varnish on enamel caries like lesions in primary teeth: in vitro study

Background

Professionally applied topical fluoride preparations have been commonly used and have proven to prevent dental decay. Alternative preparations that provide further benefits may be of interest to investigate. This study aimed to investigate the effect of experimental nano silver fluoride (NSF) formulation compared to commercial sodium fluoride varnish (FV) on prevention of in vitro demineralization of initially sound enamel in primary teeth.

Methods

Forty-eight extracted/exfoliated sound molars were sectioned buccolingually into 96 specimens then assigned randomly into two equal groups. Each group was further subdivided into two equal subgroups (Ia: NSF, IIa: FV, Ib and IIb as negative controls). The test materials were applied, then all the specimens were subjected to a demineralization pH cycling model for 7 days. Specimens were examined for surface microhardness using Vickers microhardness device and lesion depth was evaluated by polarized light microscope using image J 1.46r software. Data were analyzed using paired t-test, independent t-test, and Mann Whitney U test.

Results

The test materials were significantly superior to their negative controls, (P < 0.001) and comparable to each other, (P > 0.05) regarding microhardness and lesion depth. In comparison to FV, NSF showed lower yet statistically insignificant percent increase in microhardness and decrease in lesion depth, (P = 0.81, 0.86, respectively). Qualitative evaluation revealed that both agents reduced the lesion depth formation.

Conclusion

NSF showed similar effect to that of FV in limiting in vitro enamel demineralization caused by acidic challenge. Hence, it could be regarded as a promising alternative preventive agent in primary teeth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02271-6.

Remineralization potential of P11-4 and fluoride on secondary carious primary enamel: A quantitative evaluation using microcomputed tomography

The aim of this study was to assess the ability of self-assembling peptide (P11-4) diffusion, assembly, and remineralization to effect artificial secondary caries-like lesions in human primary teeth in vitro. Enamel-dentin blocks obtained from extracted human primary molars were embedded into epoxy resin blocks. Cavities (approximately 1 × 1 × 2 mm) were prepared on the surface using a high-speed diamond bur under constant water cooling and filled with composite restorative material (Filtek Z250; 3 M ESPE). The samples were immersed in demineralizing solution (20 ml) for 96 h to produce secondary caries lesions and divided into two groups according to the testing materials: fluoride varnish (Duraphat; Colgate, UK) and P11-4 (Curodont Repair; Credentis, Switzerland). Except for the control areas, all samples were remineralized for 3-5 min using the remineralizing agents, and then all the sections were placed in a pH-cycling system for 5 days at 35°C. The pH cycling procedure was followed by micro-CT analysis for the qualitative evaluation of surface changes. The Mann-Whitney U test was used to compare two independent groups. In the comparison of more than two dependent groups, Bonferroni smoothed pairwise analyses were used to determine the source of the Kruskal-Wallis H test difference. The results of the study revealed that the remineralization depths of the peptide group were higher than those of the fluoride group (p < .01). There was a statistically significant difference in remineralization effects between the fluoride and peptide groups. P11-4 can be considered as an effective remineralizing agent for secondary caries lesions.

Characterization of white spot lesions formed on human enamel under microcosm biofilm for different experimental periods

The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms.

Effects of NanoAg-ACP Microparticles as Bioactive Fillers on the Mechanical and Remineralization Properties of Dental Resin Cement

PURPOSE

To investigate the potential of adding silver-nanoparticle-containing amorphous calcium phosphate microparticles as bioactive fillers into commercially available non-bioactive dental resin cement.

MATERIALS AND METHODS

Experimental cement was formulated by adding 7.5% silver-nanoparticle-containing amorphous calcium phosphate microparticles to Multilink Automix resin cement (Ivoclar Vivadent). The experimental cement was evaluated for shear bond strength (N=11 per group) and demineralization/remineralization (N=16 per group), with BioCem^® Universal BioActive cement (NuSmile) as the positive control and Multilink Automix cement as the negative control. One-way analysis of variance and post hoc tests were used to assess the significance of differences among or between the groups RESULTS: : The addition of silver-nanoparticle-containing amorphous calcium phosphate microparticles at the level of 7.5% by weight into Multilink Automix did not have a statistically significant effect on the shear bond strength (p>0.05), but statistically significantly increased the depth of remineralization on both dentin and enamel (p=0.01 and p<0.001, respectively.) when compared to Multilink Automix alone. The experimental cement prepared in the present study was comparable to BioCem^® on the depths of remineralization on both dentin and enamel (p=0.59 and p=0.99, respectively).

CONCLUSION

When incorporated into non-bioactive commercial dental resin cements as bioactive fillers at the level of 7.5% by weight, silver-nanoparticle-containing amorphous calcium phosphate microparticles could provide remineralization potential without affecting the shear bond strength. This article is protected by copyright. All rights reserved.

The Efficacy of Non-fluoridated Toothpastes on Artificial Enamel Caries in Primary Teeth: An In Vitro Study

Aims

The aim of this study was to evaluate the remineralizing effect among various non-fluoridated toothpastes on artificial caries in primary teeth.

Materials and Methods

Fifty sound primary incisor teeth were embedded in self-curing acrylic resin and immersed in demineralizing solution for 4 days forming artificial caries. All teeth were divided into five groups (10 teeth/group): Group I deionized water (control); Group II 1000 ppm F (Kodomo^®); Group III non-fluoridated toothpaste containing calcium glycerophosphate and calcium lactate (Dokbuaku^®); Group IV casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) paste (GC Tooth Mousse^®), and Group V non-fluoridated toothpaste containing nanohydroxyapatite (NHA) (Apagard^®). The specimens were subjected to pH-cycling and immersed in toothpaste slurry twice for 7 days. Baseline, before, and after pH-cycling surface microhardness (SMH) values were measured by Vickers hardness numbers, and the percentage recovery of SMH (%SMHR) was calculated. Data were analyzed by one-way analysis of variance and Tukey's multiple comparison at 95% confidence intervals.

Results

The SMH values of test groups were significantly higher than those of the control group (p = 0.00). The %SMHR was -5.72±7.03% in the control group, Group II was significantly higher than Group III but there were no significant differences among Groups II, IV, and V (p > 0.05).

Conclusion

Non-fluoridated toothpastes containing CPP-ACP or NHA for young children had efficacy in remineralizing effect on primary teeth comparable with 1000 ppm fluoridated toothpaste.

Remineralization Potential of Nanohydroxyapatite Toothpaste Compared with Tricalcium Phosphate and Fluoride Toothpaste on Artificial Carious Lesions

Introduction

Nanohydroxyapatite (nano-HA) has been utilized as an alternative agent for dental enamel remineralization. This study compared remineralization potential of nano-HA toothpaste (NHT), functionalized tricalcium phosphate toothpaste (TCPT), and fluoride toothpaste (FT) on carious lesions.

Materials and Methods

Sixty extracted human premolars were prepared for artificial carious lesions with synthetic polymer gel. Samples were divided into four groups according to testing agents: NHT, TCPT, FT, and one group with no treatment (NT). Each group was subjected to pH-cycling with the application of toothpaste in slurry form twice a day (2-min each) for 10 days. Surface microhardness was measured before demineralization, after demineralization, and after pH-cycling. Hardness at different periods, percentage of hardness recovery (% HR), and percentage of remineralization potential (%RP) were determined and statistically analyzed with ANOVA and Tukey comparisons (α = 0.05). Polarized light microscopy (PLM) was utilized to assess lesion depth.

Results

Significant remineralization of carious lesions was observed among different toothpastes compared to NT (p < 0.05). No significant difference in remineralization potential was found among NHT, TCPT, and FT (p > 0.05). No significant difference in % HR and % RP was seen among NHT, TCPT, and FT (p > 0.05). PLM indicated a greater decrease in carious depth upon using NHT compared to TCPT and FT, with minimal increase in depth for NT.

Conclusions

NHT has comparable capability to TCPT and FT in hardness recovery. However, decrease in carious depth was evidenced with PLM for NHT more than TCPT and FT. Thus, NHT was suggested as a potential remineralization product for treating initial carious lesions. Clinical Significance. The study showed that NHT had the potential to remineralize artificial carious lesion. It was confirmed in potential in the lesion depth reduction and forming a new enamel layer. NHT showed its capability as an alternative for dental caries therapeutic.

Remineralizing effect of a new strontium-doped bioactive glass and fluoride on demineralized enamel and dentine

OBJECTIVE

To investigate the remineralizing effect of a strontium-doped bioactive glass (HX-BGC) and fluoride on demineralized enamel and dentine.

MATERIALS

Sixty demineralized human tooth specimens were allocated to four groups. Group 1 received 5% HX-BGC, Group 2 received 5% HX-BGC and 1450 ppm fluoride, Group 3 received 1450 ppm fluoride, and Group 4 received deionized water as negative control. The specimens were subjected to pH cycling for 14 days. The surface morphology, lesion depths, crystal characteristics and collagen matrix degradation of the specimens were assessed by scanning electron microscopy (SEM), micro-computed tomography (mico-CT), X-ray diffraction (XRD), and spectrophotometry with a hydroxyproline (HYP) assay, respectively.

RESULTS

SEM images showed the enamel surface was smooth with regularly arranged enamel rods in Groups 1-3. Granular grains were observed in both inter-tubular and intra-tubular dentine in Groups 1-3. The mean lesion depths in enamel were 80.8 μm, 50.6 μm, 72.7 μm and 130.7 μm in Groups 1-4, respectively (p < 0.001), and those in dentine were 152.6 μm, 140.9 μm, 165.4 μm and 214.1 μm, respectively (p < 0.001). The differences in mean mineral loss in enamel and in dentine between the four study groups follow the same pattern as that of the differences in lesion depth. XRD illustrated apatite formation in each group. There were no significant differences in the HYP concentrations among the four groups (p = 0.261).

CONCLUSION

Combined use of HX-BGC and fluoride can reduce mineral loss and promote remineralization of demineralized enamel and dentine through the precipitation of newly formed apatite.

CLINICAL SIGNIFICANCE

Adjunctive use of HX-BGC may enhance the remineralization effect of fluoride in the management of early dental caries lesions.

Self-assembling peptide P11-4 in remineralization of enamel caries - a systematic review of in-vitro studies

OBJECTIVE

The present systematic review was conducted to investigate the effect of the self-assembling peptide (SAP) - P₁₁-4 in the remineralization of enamel caries.

MATERIAL AND METHODS

The systematic search for studies was conducted through CINAHL, EMBASE, MEDLINE, Scopus, PsychINFO, and various key journals. This review was conducted in adherence to PRISMA standards and was registered in PROSPERO with registration number CRD42019110156. The methodological quality of the studies was graded through Cochrane's tool of risk of bias in non-randomized studies - of interventions (ROBINS-I).

RESULTS

In total, 91 studies were identified for screening, and 12 studies were eligible. Ten studies showed effective enamel remineralization with P₁₁-4 compared to controls. One study showed a combination of P₁₁-4 with fluoride varnish or Casein Phosphopeptide-Amorphous Calcium Phosphate Fluoride (CPP-ACPF) leads to significantly higher remineralization compared to P₁₁-4 alone. Quality assessment of study showed 6 (50%) studies as medium risk of bias and 6 (50%) studies as low risk of bias.

CONCLUSION

To conclude, the present study results showed SAP- P₁₁-4 is effective in the remineralization of enamel caries.

The burden of root caries: Updated perspectives and advances on management strategies

BACKGROUND

Root caries has gained much attention in the last few years. As the world's population is ageing and people currently tend to retain more teeth compared with older generations, there is an increased prevalence of periodontal disease and gingival recession, which may accelerate the onset of root caries.

OBJECTIVE

This review aims to summarise recent findings related to the diagnosis, prevention and treatment of root caries.

MATERIALS AND METHODS

MEDLINE (OVID) and Scopus (Elsevier) searches were performed to identify and discuss articles that address the pathogenicity and clinical management of root caries.

RESULTS

Root caries is a multifactorial disease. Cariogenic species involved in root caries are less dependent on carbohydrates since collagen degradation inside the dentinal tubules can provide nutrients and microcavities for the invading microorganisms. Furthermore, the root surface has fewer minerals in comparison with enamel, which may accelerate the onset of demineralisation. Root caries could be prevented by patient education, modification of risk factors, and the use of in-office and home remineralisation tools. The use of non-invasive approaches to control root caries is recommended, as the survival rate of root caries restorations is poor. When plaque control is impossible and a deep/large cavity is present, glass ionomer or resin-based restorations can be placed.

CONCLUSION

The assessment of root carious lesions is critical to determine the lesion activity and the required intervention. Dental practitioners should also be aware of different prevention and treatment approaches to design optimum oral health care for root caries-affected patients.

Comparison of demineralization around orthodontic brackets cured by conventional method and transillumination technique-an in vitro evaluation

OBJECTIVE

To compare demineralization around orthodontic brackets cured by conventional method and transillumination method.

MATERIALS AND METHOD

Sixty freshly extracted human premolar teeth were divided into four groups. Group 1: Brackets bonded with conventional method of bonding by curing labially for 40 sec. Group 2: Brackets bonded with transillumination method of bonding for 50 sec. Group 3: Brackets bonded with conventional method of bonding by curing labially for 20 sec followed by 30 sec of transillumination. Group 4: Brackets bonded with transillumination method of bonding for 30 sec followed by labial curing for 20 sec. Ground sections were prepared of each tooth and microleakage was evaluated using a binocular microscope at 40× magnification (Olympus BX53) and an image was taken using a digital camera (Olympus EPL3) connected to the microscope. The images were analyzed using Magnus Pro Image software. Scores were assigned to different degrees of microleakage at the demineralization zone around enamel-adhesive-bracket complex at the occlusal, middle, and gingival margins using linear measurement tool. Data obtained was subjected to statistical analysis using SPSS software (Version 20.0). Level of significance was kept at 5%. Intragroup comparison was done using Kruskal-Wallis test followed by Mann-Whitney U-tests for pairwise comparison.

RESULTS

Group 4 showed least mean demineralization in occlusal, middle, and cervical areas as compared to other groups and the results were statistically significant (P < 0.05).

CONCLUSION

Transillumination can be employed as a method synergistically with conventional curing to achieve minimum amount of demineralization during fixed orthodontic treatment.

Development of an Experimental Dentifrice with Hydroxyapatite Nanoparticles and High Fluoride Concentration to Manage Root Dentin Demineralization

Background

High-fluoride dentifrice is used to manage root caries, but there is no evidence whether its association with nanohydroxyapatite could provide an additional protection for root caries. Therefore, this study aimed to develop and evaluate the effect of an experimental dentifrice with high fluoride (F⁻) concentration and nanohydroxyapatite (nano-HA) on root dentin demineralization.

Materials and Methods

After formulation of dentifrices, root dentin specimens were randomly assigned to six groups (n = 10) using different dentifrice treatments: placebo; nano-HA without F⁻; 1,100 µg F⁻/g; 1,100 µg F⁻/g + nano-HA; 5,000 µg F⁻/g; and 5,000 µg F⁻/g + nano-HA. A pH cycling model was performed for 10 days, in which treatments were performed twice a day. After that period, the longitudinal hardness was evaluated and the area of demineralization (ΔS) was calculated. The formulated dentifrices were evaluated for primary stability, cytotoxicity, and other technical parameters. Two-way ANOVA and Tukey’s test with p set at 5% were used for data analysis.

Results

The experimental dentifrices were stable and had no cytotoxicity. Regarding dentin demineralization, the placebo group significantly increased ΔS compared to all other treatment groups (p<0.001). The dentifrices containing 5,000 µg F⁻/g, regardless of the presence of nano-HA, led to a smaller lesion area in relation to the other treatments (p<0.001).

Conclusion

The findings of this study suggest that nano-HA reduced dentin demineralization, and dentifrice with 5,000 µg F⁻/g dentifrices, regardless of the presence of nano-HA, showed a greater reduction in root dentin demineralization.

The effect of silver diamine fluoride in preventing in vitro primary coronal caries under pH-cycling conditions

OBJECTIVES

This study investigated the ability of SDF, and its individual components, silver (Ag⁺) and fluoride (F^-) ions, in preventing enamel demineralization under pH-cycling conditions in the presence or absence of twice-daily fluoride application.

DESIGN

Polished human enamel specimens were assigned to five treatment groups (n = 36 per group): SDF (38 %); SDF followed by application of a saturated solution of potassium iodide (SDF + KI); silver nitrate (AgNO₃; silver control, 253,900 ppm Ag); potassium fluoride (KF; fluoride control, 44,800 ppm F); deionized water. Treatments were applied once. Specimens in each treatment group were divided into two subgroups (n = 18). During the subsequent 7-day pH-cycling phase, specimens were treated twice daily with either 275 ppm fluoride as sodium fluoride or deionized water, immediately before and after a 3-h cariogenic challenge with exposure to artificial saliva at all other times. Changes in color, Vickers surface microhardness (SMH), transverse microradiography (TMR) was calculated. Data were analyzed using two-way ANOVA.

RESULTS

In both models, SDF, SDF + KI and KF were superior in inhibiting demineralization compared to AgNO₃ and deionized water (p < 0.0001). There was no statistically significant difference between SDF, SDF + KI and KF with twice daily fluoride treatments (p > 0.8). However, KF was more effective in preventing demineralization than SDF and SDF + KI in the absence of fluoride treatments (p = 0.0002). KI did not affect the ability of SDF to prevent demineralization (p > 0.4).

CONCLUSION

SDF and SDF + KI appears to be an effective option in preventing primary coronal caries.

Comparative Evaluation of Root Caries Remineralization Effect of Plain Milk, 5 ppm of Fluoridated Milk, and 5 ppm of Sodium Fluoride in Deionized Water Using Surface Microhardness Test: An In Vitro Study

Background:

There is an increase in longevity of teeth retained in elderly population, leading to increased risk of root caries. Therefore, new and affordable preventive strategies are in need to reduce this problem. Hence, the aim and objective of the study was to assess and compare the root caries remineralization effect of plain milk, 5ppm of fluoridated milk, and 5ppm of NaF in deionized water.

Materials and Methods:

The study was an in vitro experimental design. Sixty root samples were divided into five groups (sound root, demineralized root treated in deionized water, plain milk, 5-ppm fluoridated milk, and 5-ppm fluoridated deionized water) of 12 samples each after baseline surface microhardness analysis and standardization was carried out in the study. All groups except the sound root were subjected to demineralization procedure for 4 days at 37°C. The demineralized four groups were treated to test solutions and subjected to pH cycling for 14 days. This was followed with assessment of postintervention surface microhardness. Student’s paired t test was used for comparing surface within groups. One-way analysis of variance test and post hoc Tukey’s test were conducted for between groups’ comparison.

Results:

There was a significant difference between groups (P < 0.05). The results of post hoc showed that significant difference was found between the group sound root and demineralized treated with 5-ppm fluoridated milk and 5-ppm fluoridated deionized water with an effect size of 2.15 and 2.87, with CI (–26.8 to –8.1) and (–36 to –17.3), respectively. There was a significant difference in all the groups when compared within the group (P < 0.05).

Conclusion:

Plain milk, 5-ppm fluoridated milk, and 5-ppm fluoridated deionized water showed remineralizing potential against demineralized in vitro root caries samples. 5-ppm fluoridated deionized water and 5-ppm fluoridated milk have a better effect compared to plain milk.

Characterization of polymicrobial biofilms obtained from saliva or carious lesions in dentin

This study aimed to compare the formation of polymicrobial biofilms using carious dentin or saliva as inoculum for application in in vitro microbiological studies on caries research. For biofilm growth, combined samples of infected dentin or saliva from three donors were used. The biofilms were grown on glass coverslips, under a regimen of intermittent exposure (6 h day^-1) to 1% sucrose for 4 days. Total bacterial loads, as well as specific aciduric bacteria and mutans streptococci loads were quantified and correlated with biofilm acidogenicity and susceptibility to chlorhexidine. The data were evaluated using the Student's-t, Mann Whitney and Kruskal-Wallis tests. The two biofilms showed similar microbial loads (total bacteria, aciduric bacteria and mutans streptococci) on day 4, and high acidogenicity after 48 h and were susceptible to chlorhexidine at different time intervals. In conclusion, both dentin and saliva can be used as an inoculum in in vitro studies of processes related to biofilm formation.

Fluoride Mode of Action: Once There Was an Observant Dentist

The discovery and implementation of fluoride in the prevention of dental caries is often praised as one of the most important achievements in health care. In the early 20th century, it took 30 y to identify fluoride as the cause of enamel mottling but also of reduced caries prevalence in a population drinking water containing fluoride. Similarly, from 1960 to 1990, it took major efforts to unravel the working mode of fluoride in such detail that a rational scheme of caries prevention could be formulated. This article describes the scientific struggle leading to a consensus on the topic. For a historic purpose, the field, the actors, and their main research achievements are described. Ultimately it was generally agreed that the effect of fluoride is primarily topical by fluorides in the oral fluids rather than systemic by incorporation of fluoride in the enamel mineral crystals. Fluoride concentrations, even <1 mg/L, enhance the deposition of calcium phosphates during remineralization of enamel (and dentin). Similarly, such low levels of fluoride are effective in reducing the dissolution of the calcified tissues. This understanding has led to the development of fluoride-containing caries-preventive products that had an undisputed beneficial effect on the levels of dental caries.