Remineralization of initial carious lesions in deciduous enamel after application of dentifrices of different fluoride concentrations

Antibacterial effects of children's and adults' toothpastes containing different amounts of fluoride: An in vitro study

Background

In recent years, fluoride concentrations in toothpaste for children and adults have increased. However, the effects of different concentrations on bacterial activity have rarely been compared. We aimed to investigate and compare the antibacterial activity of children's and adults' toothpaste containing 500, 1000‒1100, and 1450‒1500 ppm fluoride.

Methods

Three strains of bacteria (Streptococcus mutans, Streptococcus salivarius, and Lactobacillus casei) were cultured in brain heart infusion agar. Thirty commercially available toothpaste products for children and adults containing 500, 1000‒1100, and 1450‒1500 ppm fluoride were selected and tested. Toothpaste's ability to inhibit bacterial growth was evaluated by agar diffusion assay, in which plates were incubated for 24 hours, and then the diameter of the microbial inhibition zone was measured. Comparisons between children's and adults' fluoride toothpastes were made using the Mann-Whitney U test. The association between bacterial growth inhibition and sodium lauryl sulfate (SLS) was analyzed by the chi-square test. A P value of <0.05 was considered statistically significant.

Results

No difference in the inhibition zone was observed for different fluoride concentrations. However, there were significant differences between toothpastes for children and adults, with higher inhibition zones for adults' toothpastes. Most toothpastes for adults contained SLS, which was associated with antibacterial activity.

Conclusion

Fluoride concentrations ranging from 500 to 1500 ppm did not affect bacterial growth. The antibacterial activity of toothpastes for adults was significantly higher than that of toothpastes for children, which was mainly attributed to the SLS usually added to adult formulations.

Potential Beneficial Effects of Hydroxyapatite Nanoparticles on Caries Lesions In Vitro-A Review of the Literature

Dental caries is one of the most common human diseases which can occur in both primary and permanent dentitions throughout the life of an individual. Hydroxyapatite is the major inorganic component of human teeth, consequently, nanosized hydroxyapatite (nHAP) has recently attracted researchers' attention due to its unique properties and potential for caries management. This article provides a contemporary review of the potential beneficial effects of nHAP on caries lesions demonstrated in in vitro studies. Data showed that nHAP has potential to promote mineralization in initial caries, by being incorporated into the porous tooth structure, which resulted from the caries process, and subsequently increased mineral content and hardness. Notably, it is the particle size of nHAP which plays an important role in the mineralization process. Antimicrobial effects of nHAP can also be achieved by metal substitution in nHAP. Dual action property (mineralizing and antimicrobial) and enhanced chemical stability and bioactivity of nHAP can potentially be obtained using metal-substituted fluorhydroxyapatite nanoparticles. This provides a promising synergistic strategy which should be explored in further clinical research to enable the development of dental therapeutics for use in the treatment and management of caries.

Effects of charcoal-based whitening toothpastes on human enamel in terms of color, surface roughness, and microhardness: an in vitro study

OBJECTIVE

Charcoal based oral care products have gained popularity in the last few years. The aim of this in vitro study was to compare the effects of different charcoal based whitening toothpastes on color, surface roughness and microhardness of human enamel.

MATERIALS AND METHODS

Forty-eight specimens obtained from human permanent upper incisor teeth were randomly divided into 4 groups(n=12):Group-1:Colgate Total 12(CT); Group-2:Body Kingdom(BK); Group-3:Black is White(BW), Group-4:Colgate optic white(COW). Following 4 days cycle of darkening(2-min chlorhexidine and 60-min black tea per day), a 12- week brushing(twice daily for 1 min)was performed. Color of specimens was measured using a spectrophotometer. A contact type profilometer was used to measure surface roughness (Ra) and Vicker's hardness tester was used for the changes in microhardness(VHN). A representative sample from each group was visualized by SEM. Data were analyzed by One-way ANOVA, Welch, Fisher's, Kruskall-Wallis, Wilcoxon Sign Rank and Paired t-tests(p<0.05).

RESULTS

After 12- week brushing, no differences were found among the groups in terms of color change(p=0.989). All toothpastes tested showed no clinically acceptable whitening performances. A substantial increase in surface roughness was found in all groups, except BW(p<0.05). An increase was found in microhardness with CT(p=0.013), while no changes were found with BK, BW and COW(p>0.05).Only few scratches were observed on the enamel surfaces by SEM evaluations.

CONCLUSION

Twelve week brushing with charcoal based whitening toothpastes and a regular fluoridated toothpaste presented similar effects in color of enamel. Surface roughness was increased(except BW) while microhardness was not affected(except CT) with charcoal based whitening toothpastes.

CLINICAL RELEVANCE

Charcoal based whitening toothpastes do not promise to whiten the human permanent teeth and their effects on enamel abrasion should not be disregarded.

An In Vitro Evaluation of Remineralization Potential of Functionalized Tricalcium Phosphate Paste and CPP-ACPF on Artificial White Spot Lesion in Primary and Permanent Enamel

Aim

Investigation and evaluation of remineralization potential of functionalized tricalcium phosphate paste (fTCP) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACPF) paste on artificially created white spot lesion on human primary and permanent enamel through scanning electron microscopy and microhardness assessment.

Materials and methods

Sixty freshly extracted primary and permanent teeth were selected and artificial white spot lesion were created by using standardized demineralizing solution. Remineralization was carried out using the test pastes. The assessment of demineralization and remineralization was done through a scanning electron microscope and microhardness assessment.

Results

Among the three groups, fTCP shows significantly higher increase in mean microhardness (p < 0.001) through ANOVA and the LSD post hoc test when compared to CPP-ACPF and control group. Also, the unpaired t-test showed that mean change in microhardness in permanent teeth was significantly higher than primary teeth in different time intervals for both experimental groups. Surface morphology was assessed through a scanning electron microscope.

Conclusion

Based on the results of the current study, f-TCP showed comparatively more remineralization potential than CPP-ACP with fluoride.

How to cite this article

Bhadoria N, Gunwal MK, Kukreja R, et al. An In Vitro Evaluation of Remineralization Potential of Functionalized Tricalcium Phosphate Paste and CPP-ACPF on Artificial White Spot Lesion in Primary and Permanent Enamel. Int J Clin Pediatr Dent 2020;13(6):579–584.

Impact of a toothpaste with microcrystalline hydroxyapatite on the occurrence of early childhood caries: a 1-year randomized clinical trial

The aim of this trial was to determine whether a toothpaste with microcrystalline hydroxyapatite is not inferior to a fluoride toothpaste in prevention of caries in children. This double-blinded randomized control trial compared two toothpastes regarding the occurrence of caries lesions using International Caries Detection and Assessment System (ICDAS) ≥ code 1 on the primary dentition within 336 days. The test group used a fluoride-free hydroxyapatite toothpaste three times daily while control group used a toothpaste with fluoride. 207 children were included in the intention-to-treat analysis; 177 of them finished the study per protocol. An increase in caries ICDAS ≥ code 1 per tooth was observed in 72.7% of the hydroxyapatite-group (n = 88), compared with 74.2% of the fluoride-group (n = 89). The exact one-sided upper 95% confidence limit for the difference in proportion of participants with ICDAS increase ≥ 1 (-1.4%) was 9.8%, which is below the non-inferiority margin of 20% demonstrating non-inferiority of hydroxyapatite compared to the fluoride control toothpaste. This RCT showed for the first time, that in children, the impact of the daily use of a toothpaste with microcrystalline hydroxyapatite on enamel caries progression in the primary dentition is not inferior to a fluoride control toothpaste (Clinical Trials NCT03553966).

Comparison of hydroxyapatite and fluoride oral care gels for remineralization of initial caries: a pH-cycling study

OBJECTIVE

The present in vitro study investigated if simulated daily use of hydroxyapatite-based gel (15% HAP) remineralizes early caries lesions as effective as weekly use of high fluoride (12,500 ppm) concentration gel, comparing them with artificial saliva alone.

MATERIALS AND METHODS

Three tooth blocks were produced from each of 20 bovine teeth. Caries-like lesion was created on each block by 4-day demineralization in acidified gel. The blocks were randomized into three remineralization groups (20 blocks/group); Hydroxyapatite-based gel (Karex gelée, 15% HAP, fluoride-free), fluoride-based gel (Elmex gelée, 12,500 ppm F-), and artificial saliva (AS). Remineralization was conducted using pH-cycling model for 28 days with storage in AS. The pH cycling model consisted of 2 h demineralization once daily for all groups, and 3 min HAP gel application once daily, 3 min fluoride gel application once weekly, or remain in AS only respectively. Baseline and post-test mineral loss were quantified using microradiography.

RESULTS

Paired t-tests (baseline vs. post-Test) indicated significant (p < 0.0001) remineralization in all groups. When compared against each other using Games-Howell's multiple comparison test, no significant difference in remineralization was observed between the two gels, but both gels exhibited significantly (p < 0.001) higher percentage mineral gain (HAP:39 ± 7%; fluoride:41 ± 11%) than AS alone (6 ± 2%).

CONCLUSION

Hydroxyapatite-based gel (15% HAP) was as effective as fluoride-based gel (12,500 ppm F-) in remineralizing initial caries lesion.

Comparative efficacy of a hydroxyapatite and a fluoride toothpaste for prevention and remineralization of dental caries in children

Objective

This in situ study compared the effectiveness of two toothpastes containing hydroxyapatite or 500 ppm fluoride in promoting remineralization and inhibiting caries development.

Materials and methods

Two enamel blocks (human primary teeth), one sound and one with artificially-produced caries lesion, were exposed to toothpaste containing either 10% hydroxyapatite or 500 ppm F⁻ (amine fluoride) via intra-oral appliance worn by 30 adults in two-arm double blind randomized crossover study lasting 14 days per arm (ClinicalTrials.gov: NCT03681340). Baseline and post-test mineral loss and lesion depth (LD) were quantified using microradiography. One-sided t-test of one group mean was used for intragroup comparison (baseline vs. post-test), while two-sided t-test of two independent means was used to compare the two toothpaste groups.

Results

Pairwise comparison (baseline vs. test) indicated significant (p < 0.0001) remineralization and LD reduction by either toothpaste; however, when compared against each other, there was no statistically significant difference in remineralization or LD reduction between the two toothpastes. No demineralization could be observed in sound enamel blocks exposed to either toothpaste. While F⁻ induced lesion surface lamination, HAP produced a more homogenous lesion remineralization.

Conclusions

10% hydroxyapatite achieved comparable efficacy with 500 ppm F⁻ in remineralizing initial caries and preventing demineralization. Thus the HAP toothpaste is confirmed to be equal to the fluoride toothpaste in this study.

Development of caries adjacent to composite restorations after exposure to dentifrices with different fluoride concentrations

Objective To evaluate the development of recurrent caries after exposure to fluoride dentifrices with different concentrations. Material and method: 48 samples of bovine incisors (4x4mm2) were exposed to pH cycling for 7 days before the preparation of the cavities (2mm deep). The samples were restored with a microhybrid resin composite. Then, the samples were exposed to thermal cycling (350 cycles) and they were randomly allocated into 4 treatment groups (n = 12): Group A - non-fluoridated dentifrice (negative control); Group B - 500 ppm dentifrice; Group C - 750 ppm dentifrice; group D - 1100 ppm dentifrice (positive control). The samples were treated with solutions of each dentifrice (9.6 ml water/1.6 g dentifrice) for 60 seconds and then were immersed in demineralizing (3 h) and remineralizing (2 h) solutions 3 times a day. Next, the samples were immersed in a remineralizing solution for 18 hours. Then, the blocks were sectioned for examination of the length of the outer caries lesion, using polarized light microscopy. The ANOVA parametric test complemented by the Tukey test with a confidence level of 95%, were used in the statistical analysis. Result: A smaller lesion length was observed in the group treated with the fluoride concentration of 1100 ppm F, but there were no differences between toothpastes with fluoride concentrations of 500 and 750 ppm F. Conclusion: The use of fluoride dentifrices (1100 ppm) reduces the development of caries adjacent to dental restorations.

Action of food preservatives on 14-days dental biofilm formation, biofilm vitality and biofilm-derived enamel demineralisation in situ

AIMS

The aims of this double-blind, controlled, crossover study were to assess the influence of food preservatives on in situ dental biofilm growth and vitality, and to evaluate their influence on the ability of dental biofilm to demineralize underlying enamel over a period of 14 days.

MATERIALS AND METHODS

Twenty volunteers wore appliances with six specimens each of bovine enamel to build up intra-oral biofilms. During four test cycles of 14 days, the subjects had to place the appliance in one of the assigned controls or active solutions twice a day for a minute: negative control 0.9 % saline, 0.1 % benzoate (BA), 0.1 % sorbate (SA) and 0.2 % chlorhexidine (CHX positive control). After 14 days, the biofilms on two of the slabs were stained to visualize vital and dead bacteria to assess biofilm thickness (BT) and bacterial vitality (BV). Further, slabs were taken to determine mineral loss (ML), by quantitative light-induced laser fluorescence (QLF) and transversal microradiography (TMR), moreover the lesion depths (LD).

RESULTS

Nineteen subjects completed all test cycles. Use of SA, BA and CHX resulted in a significantly reduced BV compared to NaCl (p < 0.001). Only CHX exerted a statistically significant retardation in BT as compared to saline. Differences between SA and BA were not significant (p > 0.05) for both parameters. TMR analysis revealed the highest LD values in the NaCl group (43.6 ± 44.2 μm) and the lowest with CHX (11.7 ± 39.4 μm), while SA (22.9 ± 45.2 μm) and BA (21.4 ± 38.5 μm) lay in between. Similarly for ML, the highest mean values of 128.1 ± 207.3 vol% μm were assessed for NaCl, the lowest for CHX (-16.8 ± 284.2 vol% μm), while SA and BA led to values of 83.2 ± 150.9 and 98.4 ± 191.2 vol% μm, respectively. With QLF for both controls, NaCl (-33.8 ± 101.3 mm(2) %) and CHX (-16.9 ± 69.9 mm(2) %), negative values were recorded reflecting a diminution of fluorescence, while positive values were found with SA (33.9 ± 158.2 mm(2) %) and BA (24.8 ± 118.0 mm(2) %) depicting a fluorescence gain. These differences were non-significant (p > 0.05).

CONCLUSION

The biofilm model permited the assessment of undisturbed oral biofilm formation influenced by antibacterial components under clinical conditions for a period of 14 days. An effect of BA and SA on the demineralization of enamel could be demonstrated by TMR and QLF, but these new findings have to be seen as a trend. As part of our daily diet, these preservatives exert an impact on the metabolism of the dental biofilm, and therefore may even influence demineralization processes of the underlying dental enamel in situ.

In situ remineralization of white-spot enamel lesions by 500 and 1,100 ppm F dentifrices

The aim of this study was to evaluate the remineralization potential of three silica-containing NaF dentifrice systems in an intraoral model. Subjects (N = 30) in this randomized, three-phase, 28-day, crossover study served as their own control. Each participant wore a customized orthodontic appliance attached to a mandibular molar and contained one tooth block with caries-like lesion. For each phase, participants engaged in twice-daily brushing for 2 min with one of the following dentifrices: 500 ppm F, 500 ppm F plus functionalized β-tricalcium phosphate (fTCP), and a clinically proven 1,100 ppm F. After each phase, appliances were removed, and specimens were analyzed using surface microhardness (SMH), transverse microradiography (TMR), and cross-sectional microhardness (CSMH). Statistically significant (p < 0.05) remineralization of white-spot lesions relative to baseline occurred for each dentifrice as determined with SMH and TMR. No significant differences (p > 0.05) in SMH were found among the three groups, but trending revealed the 500 ppm F plus fTCP produced 26% and 27% greater SMH recovery relative to 500 and 1,100 ppm F, respectively. Similarly, no significant differences (p > 0.05) in TMR were found among the groups. However, the 500 ppm F plus fTCP dentifrice produced 10% and 38% greater mineral recovery relative to 500 and 1,100 ppm F, respectively, while reducing the lesion depth 30% and 52%, respectively. Significant differences (p < 0.05) in CSMH existed among the three dentifice groups at different enamel depths, but statistical differences (p < 0.05) in relative lesion size were only found between 500 ppm F plus fTCP and 500 ppm F. The combination of fTCP and fluoride in a single-compartment, water-based dentifrice can cooperate with fluoride to produce significant remineralization. These results suggest that the combination of 500 ppm F with fTCP may provide comparable anticaries benefits relative to a 1,100 ppm F dentifrice.