The protective effects of toothpaste against erosion by orange juice: Studies in situ and in vitro

Health effects of drinking 100% juice: an umbrella review of systematic reviews with meta-analyses

CONTEXT

Low fruit and vegetable intakes are major modifiable determinants of disease. One hundred percent juice may facilitate intake and deliver essential nutrients and bioactive compounds. However, the position of 100% juice in healthy eating guidelines remains controversial due to its lower dietary fiber and higher free-sugar contents compared with whole fruits and vegetables.

OBJECTIVE

To conduct an umbrella review of systematic literature reviews with meta-analyses (MAs) to summarize the health benefits of drinking 100% fruit and/or vegetable juice.

DATA SOURCES

Four databases (Medline, The Cochrane Library, EMBASE, and CINAHL) were systematically searched for MAs of 100% juice and any health outcomes.

DATA ANALYSIS

Screening, quality, risk of bias, and content overlap tools were applied, and extracted data were narratively synthesized. No eligible studies for vegetable juice were found. Fifteen systematic literature reviews (51 primary MAs, 6 dose-response, and 87 subanalyses; 50-1200 mL/day; hours to years of duration) were included. Ten MAs (19.6%) reported health benefits (4 for blood pressure, 2 for vascular function, 3 for inflammation, 1 for stroke mortality), 3 MAs (5.9%) reported adverse risks (1 each for cardiovascular disease mortality, prostate cancer, type 2 diabetes risk), while most (74.5%) reported no effect (blood lipids, body composition, liver function, metabolic health, cancers, and inflammation). Risks were limited to cohort studies and benefits were found in both cohort and intervention studies.

CONCLUSION

The findings collate evidence showing some potential health benefits associated with 100% juice consumption, with fewer potential risks. The balance of evidence does not support the exclusion of 100% juice from food-based guides to healthy eating, although caution may be warranted in certain groups or individuals, and the body of evidence is not yet conclusive.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022380588.

Should We Wait to Brush Our Teeth? A Scoping Review Regarding Dental Caries and Erosive Tooth Wear

BACKGROUND

Tooth brushing is a universal recommendation. However, the recommendations related to the time of its execution are conflicting, especially when dealing with patients at risk of erosive tooth wear (ETW) or dental caries.

SUMMARY

Our objective was to summarize the evidence on the timing of brushing with fluoridated toothpaste in relation to ETW and cariogenic dietary challenges. We conducted a scoping review following the PRISMA-ScR checklist, using three databases searching for in vivo, in situ, or in vitro studies involving human teeth exposed to either a cariogenic or an erosive challenge. Only models including human saliva and fluoride were assessed. Data selection, extraction, and risk of bias analysis were done in duplicate and independently. From 1,545 identified studies, 17 (16 related to ETW and 1 to dental caries) were included. Most evidence (n = 10) supported that brushing with a fluoride-containing product does not increase ETW, independent of the moment of brushing. Delaying tooth brushing up to 1 h (n = 4) or individualized recommendations based on the patient's problem (n = 2) were less frequent. Only one study reported that brushing pre- or post-meal does not affect Streptococcus mutans counts. Most data were in situ (n = 13), and the overall study quality was judged as sufficient/low risk of bias.

KEY MESSAGES

Although the available evidence lacked robust clinical studies, tooth brushing using fluoridated products immediately after an erosive challenge does not increase the risk of ETW and can be recommended, which is in line with recommendations for dental caries prevention. Furthermore, we suggest updating the international guidelines to promote individualized recommendations based on risk factors to prevent either ETW or dental caries.

The role of calcium in the prevention of erosive tooth wear: a systematic review and meta-analysis

OBJECTIVES

The loss of hard dental tissue due to recurrent acid challenges and mechanical stresses without bacterial involvement is known as erosive tooth wear (ETW). Many studies in the literature have concentrated on variables that may affect the ETW process and prevent its occurrence or reduce its advancement. However, to date, no previous systematic review has evaluated the role of calcium in preventing ETW. Therefore, the purpose of the present systematic review was to review and critically appraise the scientific evidence regarding the role of calcium formulations in the prevention of ETW.

METHODS

The review protocol was registered in the PROSPERO international prospective register of systematic reviews (Ref: CRD42021229819). A literature search was conducted in electronic databases to identify in situ randomized controlled trials evaluating the prevention of ETW following the application of calcium formulations. The outcomes studied included mean enamel loss, surface microhardness, surface roughness, mean erosion/softening depth, mineral loss/precipitation and remineralization. Study characteristics and outcomes of included studies were summarized. Cochrane's risk-of-bias tool 2.0 was used to assess the quality of eligible studies, and meta-analysis using a random effects model was performed.

RESULTS

The search retrieved 869 studies of which 21 were considered eligible. Regarding the results of the quality assessment for potential risk of bias in all included studies, overall, 5 studies were considered as being at low risk, another 12 at unclear risk and 4 at high risk of bias. The findings of the studies showed that the addition of calcium in juice drinks led to reduced enamel loss, with blackcurrant juice presenting 2.6 times statistically significant less enamel loss compared to orange juice (p = 0.0001, I2 = 89%). No statistically significant difference in mean surface microhardness of eroded enamel was recorded between chewing gum with or without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (p = 0.31, I2 = 71%). Contradictory were the results regarding the effect of milk and CPP-ACP pastes on prevention of ETW.

CONCLUSIONS

Calcium formulations play an important role in ETW prevention, mainly through their addition to acidic drinks.

Interaction between Hexametaphosphate, Other Active Ingredients of Toothpastes, and Erosion-Abrasion in Enamel in vitro

Sodium hexametaphosphate (HMP) as toothpaste additive is claimed to reduce erosive tooth wear and to stabilize stannous ions. However, little is known about the impact of concentration and its interactions with fluoride (F) or stannous+fluoride ions (F/Sn) on enamel erosion and erosion-abrasion. In a 10 day cyclic in vitro erosion-abrasion model, 320 flat human enamel specimens were divided into ten groups (n = 32 each) and daily subjected to six erosive challenges (0.5% citric acid, 2 min) and two toothpaste suspension applications (2 min, 1:3 F-free toothpaste:mineral-salt solution, 0.23% sodium gluconate). Half of specimens per group were additionally brushed twice/day (200 g, 15 s) during suspension immersion. Nine suspensions contained HMP (0.25%, 1.75%, 3.25%), either on its own or combined with F (373 ppm F-) or F/Sn (800 ppm Sn2+, 373 ppm F-). One suspension contained sodium gluconate only (NegContr). After 10 days, specimens' surfaces were analysed with profilometry, energy dispersive X-ray spectroscopy, and scanning electron microscopy. Tissue loss (µm, mean ± standard deviation) in NegContr was 10.9 ± 2.0 (erosion), 22.2 ± 1.6 (erosion-abrasion). Under erosive conditions, only 0.25% HMP in any combination and 1.75% HMP with F/Sn reduced loss significantly (-28% to -54%); 3.25% HMP without F and F/Sn increased loss significantly (+35%). With additional abrasion, no suspension reduced loss significantly compared to NegContr, instead, in groups without F and F/Sn or with 3.25% HMP loss was increased (+15% to +30%). Conclusively, at higher concentrations, HMP increased erosive tooth wear and seemed to reduce anti-erosive effects of fluoride and stannous ions.

A Comparative Study of the Effect of Tooth Mousse Plus Remin Pro and Fluor Protector Gel on Enamel Erosion: An In Vitro Study

Background

The purpose of this in vitro study was to assess the effect of Tooth Mousse Plus, Remin Pro, and Fluor Protector Gel on enamel erosion, measuring mean weight loss after exposure to a demineralizing agent.

Materials and methods

A total of 60 sound-extracted permanent incisors were sectioned and enamel specimens were randomly distributed to different groups. The initial weight of all specimens was registered. The samples were randomly divided into four groups (n = 30). Group I specimens were treated with tap water (control). Groups II, III, and IV were treated with Tooth Mousse, Remin Pro, and Fluor Protector Gel application. After that, specimens were placed all together in a plastic container with 6 mL of a soft drink and immersed for 8 minutes at room temperature, dried, and weighed. Specimens were weighed after each immersion period and mean weight loss was calculated. The data was analyzed for probability distribution using the Kolmogorov-Smirnov test. The intergroup comparison was done using a one-way analysis of variance (ANOVA) followed by post hoc analysis.

Results

According to pairwise comparisons in post hoc analysis, the weight of specimens at baseline was significantly greater than the weight of specimens on day 12. The difference in the mean weight of the specimen from baseline to day 12 was 2.833 mg for group I, 2.367 mg for group II, 1.467 mg for group III, and 2.133 mg for group IV.

Conclusion

Tooth Mousse Plus, Remin Pro, and Fluor Protector Gel have no significant effect on dental erosion.

How to cite this article

Shukla K, Saxena A, Joshi J, et al. A Comparative Study of the Effect of Tooth Mousse Plus Remin Pro and Fluor Protector Gel on Enamel Erosion: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S57-S62.

Impact of different brushing/abrasion protocols on erosive tooth wear for in vitro studies

OBJECTIVE

To investigate the influence of different toothbrushing (with dentifrice) protocols on the progression of erosive tooth wear for in vitro studies.

DESIGN

Bovine enamel specimens were randomly distributed into 12 experimental groups (n = 10), according to the study factors: (1) brushing movement (horizontal or circular); (2) slurry diluent (artificial saliva or distilled water); (3) toothpaste dilution ratio (1:2, 1:3 or 1:4). A 5-day erosion-abrasion cycling model was performed, each consisting of 4 erosive challenges (0.3 % citric acid, pH=2.6) followed by 60 min exposure to artificial saliva. Brushing with fluoride toothpaste (15 s, 1400 ppm F^-, AmF) was carried out 2x/day. Enamel surface loss (SL) was determined by optical profilometry. Data were statistically analyzed with three-way ANOVA and Tukey tests (α = 0.05).

RESULTS

SL was lower for the horizontal movement than for the circular (p = 0.044). There were no significant differences among the dilution ratios for artificial saliva. For distilled water, the more concentrated slurry (1:2) presented greater surface loss than the less concentrated slurries (1:3 and 1:4, p = 0.049 and p = 0.014, respectively). Dilutions with artificial saliva at ratios 1:3 and 1:4 presented higher surface loss than with distilled water (p = 0.008 and p < 0.001, respectively); however, for 1:2 ratio, there were no significant differences between the diluents.

CONCLUSIONS

The in vitro progression of enamel SL was influenced by the brushing movement, as well as the combination of the dilution ratio and the diluent of the toothpaste slurry, and therefore, all these factors must be considered when comparing results from different studies.

Film-Forming Polymers for Tooth Erosion Prevention

Different agents have been proposed to prevent the progression of acid induced dental substance losses, which are called erosive tooth wear (ETW), such as fluorides, calcium, and phosphate-based products; however, there is a need for a further increase in efficacy. Recently, the ability of polymers to interact with the tooth surface, forming acid resistant films, has come into the focus of research; nevertheless, there is still the need for a better understanding of their mode of action. Thus, this article provides an overview of the chemical structure of polymers, their mode of action, as well as the effect of their incorporation into oral care products, acid beverages, and antacid formulations, targeting the prevention of ETW. Recent evidence indicates that this may be a promising approach, however, additional studies are needed to confirm their efficacy under more relevant clinical conditions that consider salivary parameters such as flow rate, composition, and clearance. The standardization of methodological procedures such as acid challenge, treatment duration, and combination with fluorides is necessary to allow further comparisons between studies. In conclusion, film-forming polymers may be a promising cost-effective approach to prevent and control erosive demineralization of the dental hard tissue.

Erosion of CAD/CAM restorative materials and human enamel: An in vitro study

This in vitro study used the same frequency and duration of acid contact as a previous in situ/in vivo study to evaluate the effect of erosion on CAD/CAM restorative materials and human enamel and to compare the effects of in vitro and in situ/in vivo acid challenges on CAD/CAM restorative materials and human enamel. The CAD/CAM restorative materials (IPS e.max CAD, Lava Ultimate, and PMMA block) and human enamel were eroded by immersion in 150 ml of cola drink for 14 days (4 × 5 min/day). The surface microhardness and surface roughness of the specimens were measured at baseline (T1), day 7 (T2), and day 14 (T3). The substance losses were measured at T2 and T3. The data were statistically analyzed using repeated measures ANOVA and Bonferroni's test (α = 0.05). Erosion significantly decreased the surface microhardness of the CAD/CAM restorative materials and human enamel (all P < 0.001). The overall percentage of surface microhardness loss (%SMH_l) of the PMMA block and enamel due to in vitro erosion was significantly higher than that due to in situ/in vivo erosion (P = 0.02 and P < 0.001, respectively). Consistent with in situ/in vivo erosion, the surface roughness and profile of the tested restorative materials remained unchanged after in vitro erosion. A significant increase in the surface roughness and substance loss was observed for enamel after in vitro erosion (all P < 0.001). The overall substance loss of enamel due to in vitro erosion was significantly higher than that due to in situ/in vivo erosion (P < 0.001). In conclusion, erosion decreased the surface microhardness of the CAD/CAM restorative materials and human enamel. Moreover, erosion negatively influenced the substance loss and surface roughness of human enamel. For the substance loss of enamel and %SMH_l of PMMA block and enamel, the in vitro erosive effects were approximately 1-2 times greater than the in situ/in vivo effects. However, for the surface roughness and profile of the CAD/CAM restorative materials, no significant difference was found between in vitro and in situ/in vivo erosion.

Bioavailable gluconate chelated stannous fluoride toothpaste meta-analyses: Effects on dentine hypersensitivity and enamel erosion

OBJECTIVES

To compare the effect of bioavailable gluconate-chelated stannous fluoride (SnF₂) toothpaste with control toothpastes for treatment of dentine hypersensitivity (DH) and enamel erosion.

DATA AND SOURCES

A Procter & Gamble Oral Care archive of clinical studies was reviewed from 2000 to 2020. Eligible studies were Randomised Controlled Trials (RCTs) investigating bioavailable gluconate-chelated SnF₂ toothpaste efficacy compared to controls in adult participants measured following tactile (Yeaple force) and/or evaporative stimuli (Schiff score) in-vivo, duration <2 months (DH); or by erosive toothwear (profilometry) from in-situ samples, duration 10-15 days. Two authors independently assessed eligibility and resolved disagreements by discussion. A meta-analysis was undertaken and Risk of Bias (RoB) assessed using the Cochrane collaboration RoB tool for randomized parallel-group and cross-over trials.

RESULTS

Fourteen RCTs (1287 participants) assessed DH relief and Six RCTs (184 participants) enamel erosion protection. For DH SnF₂ toothpastes provided a 57 % (evaporative air) and 142 % (tactile) benefit versus negative controls (sodium fluoride/monofluorophosphate, 8 studies; p < 0.001). Compared to positive controls (potassium nitrate or arginine, 6 studies), a 22 % advantage (p = 0.036) was seen for evaporative air. In erosion studies, SnF₂ toothpastes provided an 83 % benefit versus control toothpastes (arginine or sodium fluoride; p < 0.001) with a change (95 %CI) in average surface profilometry level (μm) of -2.02(-2.85, -1.20).

CONCLUSIONS

The use of these bioavailable SnF₂ toothpastes, as part of a daily oral hygiene regimen, will provide patients with enamel erosion protection, combined with alleviation of DH pain when present, improving quality of life.

Stannous Fluoride Preventive Effect on Enamel Erosion: An In Vitro Study

The aim of this in vitro study was to evaluate the effects of a single dose application of two daily toothpastes on enamel exposed to acid attack. The research was conducted on human molars enamel fragments (n = 72). The two different toothpastes active ingredients were sodium fluoride (NaF) and stannous fluoride (SnF₂). They were compared in protecting the surface of the enamel exposed to three acids: citric acid, lactic acid and hydrochloric acid. A spectrophotometer was used to measure the calcium ions and phosphate released in the solutions by the enamel specimens. Afterward, ionic concentrations were analyzed through the t-Student test, in order to estimate the significance level (p < 0.05) of the solubility differences obtained between the treatment and control groups. Finally, sample surfaces were analyzed with scanning electron microscopy and X-ray energy dispersive spectroscopy (SEM/EDX). The two analyzed toothpastes did not reveal any statistically significant variation in the release of calcium and phosphate (p > 0.05). Nevertheless, acid-resistant deposits were detected in samples treated with stannous fluoride and exposed to lactic acid, though the presence of tin ion deposits on samples treated with stannous fluoride was not shown. A single dose of a fluoride-based toothpaste before different acids attack, in simulated oral cavity conditions, did not show a significant preventive effect.

Hydraulic conductance of dentin after treatment with fluoride toothpaste containing sodium trimetaphosphate microparticles or nanoparticles

OBJECTIVES

To evaluate the hydraulic conductance of dentin after treatment with fluoride toothpastes containing sodium trimetaphosphate microparticles (TMPmicro) or nanoparticles (TMPnano).

MATERIALS AND METHODS

The dentinal tubules of bovine dentin blocks (4 × 4 × 1 mm) were unobstructed for determination of the maximum hydraulic conductance of the dentin. The dentin blocks were randomized into four groups (n = 15/group) of toothpastes (placebo, 1100 ppm F, and 1100 with 3% TMPmicro or 3% TMPnano) which were applied for 7 days (2×/day) using a brushing machine. The dentin surface (5/group) was analyzed by scanning electron microscopy. The hydraulic conductance post-treatment was measured in the other ten blocks. Thereafter, the same blocks were immersed in citric acid (pH 3.2) for 1 min, and the conductance was determined again. The data were submitted to 2-way ANOVA repeated measures, followed by the Student-Newman-Keuls test (p < 0.05).

RESULTS

The percentage conductance reduction post-treatment for the groups were placebo = 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). After acid attack, the percentage reduction was placebo < 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). The toothpastes containing TMP showed the highest obliteration of dentinal tubules.

CONCLUSIONS

The addition of TMPmicro to fluoride toothpaste produced a greater reduction in hydraulic conductance when compared with 1100 ppm F toothpaste.

CLINICAL RELEVANCE

The increased capacity of toothpastes containing TMP to reduce hydraulic conductance indicates their potential to reduce symptoms of dentinal hypersensitivity.

Role of desensitizing/whitening dentifrices in enamel wear

OBJECTIVES

To analyze the impact of desensitizing (D) and/or whitening (W) dentifrices on erosion and erosion-abrasion.

METHODS

Enamel specimens were allocated into 10 groups (n = 20): 1. Artificial saliva (control); 2. Sensodyne Repair&Protect (SRP-D); 3. Sensodyne Repair&Protect Whitening (SRP-W); 4. Colgate Sensitive Pro-Relief (CSPR-D); 5. Colgate Sensitive Pro-Relief Real White (CSPRR-W); 6. Colgate Total 12 (CT); 7. Colgate Total 12 Professional Whitening (CTP-W); 8. Sensodyne True White (ST-W); 9. Curaprox Black is White (CB-W); 10. Oral-B 3D White Perfection (OB3D-W). For abrasion (n = 10), 30,000 brushing strokes were performed and surface roughness (SR) was evaluated. Erosion-abrasion (n = 10) consisted of 1 % citric acid (2 min), artificial saliva (60 min); 6×/day; 5 days. Toothbrushing was carried out 2×/day (45 strokes). Surface loss (SL) was determined with an optical profilometer. Data were statistically analyzed (α = 0.05).

RESULTS

Relative to SR, only OB3D-W had a significantly rougher surface than the control (p = 0.014). SRP-D, CSPR-D and ST-W showed no difference from the baseline. High SL was observed for ST-W, OB3D-W and CTP-W, without significant differences from the control. CT showed the lowest SL, not differing from SRP-D and SRP-W. There was a weak negative correlation between SL and concentration of free fluoride in the slurries, SL and SR, and SL and pH, all p > 0.05.

CONCLUSIONS

Only one dentifrice increased surface roughness of enamel to a higher degree than brushing with saliva. Brushing with the test dentifrices did not cause higher enamel erosive wear than brushing with saliva.

CLINICAL SIGNIFICANCE

This study enhances our knowledge on the effect of desensitizing and whitening dentifrices, indicating that they do not worsen enamel loss due to abrasion and they might be a safe option for individuals with erosive tooth wear.

Evaluating the buffering and acid-resistant properties of eggshell-titanium dioxide composite against erosive acids

OBJECTIVE:

This paper reports on the buffering and acid-resistant properties of a modified eggshell-titanium composite against citric acid attack.

MATERIALS AND METHODS:

Eggshell-titanium EB-TiO₂ was prepared by ball-milling eggshell powder and titanium dioxide. Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) were used to characterize EB-TiO₂. The buffering property against citric acid at pH values of 2, 4, and 5 was measured using a pH meter. Five brands of toothpaste (Colgate, Colgate Sensitive, Aquafresh, Oralwise, and Sensodyne) were used to assess the acid-resistant properties of EB-TiO₂. Enamel models were simulated by dissolving each brand of toothpaste with eggshell (control) and EB-TiO₂. The samples were exposed to citric acid of pH 2. The average slope (kPa/s) was measured using a pressure sensor. An analysis of variance was used to analyze the kPa/s values (α =.05).

RESULTS:

The FTIR and XRD analyses suggest the surface modification of EB-TiO₂. The TEM image revealed spherical-shaped particles in EB-TiO₂. The pH test results showed that the buffering properties of eggshell and EB-TiO₂ were comparable. Significant differences were observed in the acid resistance properties of the samples exposed to citric acids ( P < .05). The Colgate toothpaste infused with eggshell powder had the highest mean kPa/s values, whereas Sensodyne infused with EB-TiO₂ had the lowest kPa/s values.

CONCLUSION:

The salient features of this study indicate that modification of eggshell with titanium dioxide does not affect its carbonate buffering properties. Connecting the kPa/s values to acid-resistant properties, EB-TiO₂ effectively reduces erosive attacks when added to toothpaste.

Antierosive Effect of Topical Fluorides: A Systematic Review and Meta-Analysis of In Situ Studies

BACKGROUND:

The effectiveness of the application of topical fluorides in prevention of erosive tooth wear has been an issue of controversy in the literature. The objective of this systematic review was to assess in situ studies investigating the effects of using topical fluorides on prevention of erosive tooth wear

MATERIAL AND METHODS:

Two electronic databases PubMed/MEDLINE and Cochrane Central Register of Controlled Trials were searched. Eligibility criteria included in situ-controlled studies that assessed the effect of the erosive process without additional tooth brushing. The search involved English-written articles only. A total of 684 potentially relevant titles and abstracts were found after removal of duplicates, of which 22 full-text articles were selected. Seventeen studies were included in the qualitative synthesis of which 6 studies included in the meta-analysis. The following data were obtained for each study: authors, year of publication, country, study design, periods of study, duration, blinding, interventions (type/concentration/form), tooth substrate, location of the intraoral appliance, number of samples attached to each appliance, type of acidic media used for erosive challenge, duration of erosive challenge, subjects (number/age/sex), reported side effects -if any-, measuring device, amounts of tissue loss.

RESULTS:

The risk of bias of the included studies was assessed using the Cochrane Collaboration tool for assessing the risk of bias. A meta-analysis of the present study was performed using Comprehensive Meta-Analysis version 2.2.048 software.

CONCLUSION:

The use of oral hygiene products containing AmF/NaF/SnCl2 or NaF may be effective in the prevention of erosive tooth wear.

Effects of dentifrices on mechanical resistance of dentin and restorative materials after erosion and abrasion

The aim of this study was to evaluate the mechanical resistance of dentin and restorative materials submitted to erosive/abrasive challenges with different dentifrices. The dentin was restored using a resin-modified glass-ionomer (RMGIC) or a composite resin (RC). One hemiface of the sample was protected, and the other was subdivided according to the applied dentifrice (n = 10): without fluoride (SF), sodium fluoride (NaF) and stannous fluoride (SnF). The specimens were submitted to erosive/abrasive cycles, the varnish was removed, and the Martens hardness (HMV) and elastic modulus (Eit) were evaluated. The data were analyzed by repeated two-way ANOVA measurements and Tukey tests (alpha = 0.05). When analyzing the HMV on the test side, there was no influence of the dentifrices in the dentin; however, the orders of NaF < SnF = SF in RC and SnF > NaF = SF in RMGIC were observed. Comparing the treated surfaces, there were no differences in the dentin, and only the SF since CR presented an HMV superior to that of RMGIC. Comparing control and test sides, both dentins obtained a decreased HMV after the erosive/abrasive challenge; for the restorative materials, superior values were found only for SnF in the RMGIC. The Eit values were influenced more by the dentifrices on the test side for the dentin adjacent to the RMGIC, with the lowest values shown for the SF, and for both materials, the highest values were shown for the SnF group. No differences were found when comparing each dentin treated with the same dentifrice; however, the RMGIC presented a superior Eit than the CR when brushed with both dentifrices with a fluoride. Comparing the control and test sides, the same results were obtained for the HMV. The dentifrices showed little influence on the dentin substrate, whereas the dentifrice with SnF enhanced the mechanical properties of the restorative materials, which was more evident in the RMGIC.

Is the dentifrice containing calcium silicate, sodium phosphate, and fluoride able to protect enamel against chemical mechanical wear? An in situ/ex vivo study

OBJECTIVES

The aim of this study was to investigate the effect of a dentifrice that contains calcium silicate, sodium phosphate, and fluoride on erosive-abrasive enamel wear.

MATERIAL AND METHODS

This randomized, single-blind in situ/ex vivo study was conducted with four crossover phases of 5 days (one group tested per phase). Bovine enamel blocks (n = 256) were allocated to 16 volunteers and 8 groups. The groups under study were test dentifrice, with calcium silicate, sodium phosphate, and 1450 ppm sodium monofluorophosphate; tin dentifrice, with 3500 ppm stannous chloride, 700 ppm amine fluoride, and 700 ppm sodium fluoride; conventional dentifrice, with 1450 ppm sodium monofluorophosphate; and control (deionized water). Half of the enamel blocks were subjected to erosion and the other half to erosion plus abrasion. The daily extraoral protocol consisted in four citric acid exposures (2 min) and two applications of dentifrice slurry on all blocks for 30 s; after, half of the blocks were brushed for 15 s. The response variable was enamel loss. Data were analyzed by two-way ANOVA and Fisher's test (p < 0.05).

RESULTS

For erosion, the test dentifrice promoted less enamel loss than water (4.7 ± 3.1 and 5.8 ± 2.5 μm, respectively, p < 0.05), and did not differ from tin (4.8 ± 2.5 μm) and conventional (4.8 ± 1.4 μm) dentifrices (p > 0.05). However, the test dentifrice (7.7 ± 3.8 μm) promoted higher wear after erosive plus abrasive procedures than tin (5.4 ± 1.5 μm) and conventional (6.2 ± 1.7 μm, p < 0.05) dentifrices, and did not differ from water (6.9 ± 2.0 μm).

CONCLUSIONS

The investigated dentifrice reduced enamel loss against acid challenge but had no effect against acid and brushing challenge.

CLINICAL RELEVANCE

Little is known regarding the preventive effect of dentifrices indicated for dental erosion. The tested anti-erosive dentifrice was unable to protect enamel when erosion was associated to toothbrushing abrasion.

Chitosan Biomaterials for Current and Potential Dental Applications

Chitosan (CHS) is a very versatile natural biomaterial that has been explored for a range of bio-dental applications. CHS has numerous favourable properties such as biocompatibility, hydrophilicity, biodegradability, and a broad antibacterial spectrum (covering gram-negative and gram-positive bacteria as well as fungi). In addition, the molecular structure boasts reactive functional groups that provide numerous reaction sites and opportunities for forging electrochemical relationships at the cellular and molecular levels. The unique properties of CHS have attracted materials scientists around the globe to explore it for bio-dental applications. This review aims to highlight and discuss the hype around the development of novel chitosan biomaterials. Utilizing chitosan as a critical additive for the modification and improvement of existing dental materials has also been discussed.

A novel approach to study in situ enamel erosion and abrasion lesions

OBJECTIVES

This study investigated previous hypotheses that the tongue can abrade acid softened/eroded enamel surfaces.

METHODS

Twelve upper removable appliances each retaining 2 anterior and 2 posterior human enamel specimens were constructed. Each specimen was exposed to acid on both surfaces, but only one surface was allowed contact with the tongue. Therefore, 96 surfaces were assessed. Appliances were worn from 9.30 to 17.00 Monday to Friday for 22days. Acid eroded lesions were created by immersing the specimens for 5min in 50ml orange juice three times daily. Enamel loss was measured using Quantitative light- induced fluorescence (QLF) and Non- contact profilometry (NCLP) and the differences (D) between tongue (D_t) and palate facing (D_P) surfaces determined.

RESULTS

%ΔF_D(t-p) from the two anterior specimens were greater than from those placed posteriorly with mean values of 15.9% (±9.1) and 14.4% (±8.4), 5.6% (±8.7) and 4.5% (±6.6) respectively. Similarly, NCLP data showed anterior specimens had greater differences for mean step height (MSH) between tongue- facing and the palate- facing (control) surfaces than posterior specimens. MSH_D(t-p) values were 59.4μm (±30.3) for anterior tongue facing surfaces and 55.5μm (±29.4) for posterior palate facing surfaces. For the posterior specimens MSH was 48.1μm (±26.1) and 51.7μm (±30.4) respectively (p<0.05).

CONCLUSION

The greater enamel surface loss of the anterior specimens demonstrates that abrasion by the tongue on acid softened/eroded enamel in situ is likely.

Do Abrasives Play a Role in Toothpaste Efficacy against Erosion/Abrasion?

Abrasives may counteract the efficacy of anti-erosion toothpastes either due to physical effects or due to interaction with active agents. This study aimed to investigate whether the amount of abrasives is a determinant for the efficacy of Sn2+-containing toothpastes with or without chitosan additive. Enamel samples were eroded (0.50 wt% citric acid, pH 2.5; 6 × 2 min/day) on a shaking desk - 30/min in experiment 1 (E1) and 35/min in experiments 2 (E2) and 3 (E3) - and immersed in toothpaste slurries (2 × 2 min). Half of the samples were additionally brushed (15 s, load 200 g) within the immersion time. The toothpastes contained 0, 5, 10, 15, and 20% silica. In E1 and E2 the active ingredients were F- (700 ppm as amine fluoride, 700 ppm as NaF) and Sn2+ (3,500 ppm as SnCl2); in E3 chitosan (0.5%) was additionally added. The placebo contained 20% silica. Tissue loss was determined profilometrically. In E1, slurries completely inhibited tissue loss; distinct surface deposits occurred. With brushing, tissue loss significantly increased up to an abrasive content of 10%, but decreased significantly with higher amounts; 20% silica revealed similar values as the abrasive-free formulation. In E2, all slurries inhibited tissue loss distinctly irrespective of the amounts of abrasives. With brushing, a similar trend as in E1 was observed but with much less efficacy. The chitosan-containing formulations in E3 were much more effective; similar results as in E1 were found. In conclusion, the amount of abrasives had no effect when toothpastes were applied as slurries, but played an important role with brushing.

Effect of toothpastes containing different NaF concentrations or a SnF2/NaF combination on root dentine erosive lesions, in vitro

BACKGROUND

Fluoride toothpastes presumably offer some protection against acid erosion. However, uncertainty exists towards fluoride's efficacy relatively to the concentration and the type of chemical compound used. This in vitro study evaluated the relative efficacy of toothpastes containing sodium fluoride in different concentrations or a stabilized stannous fluoride/sodium fluoride system on root dentine erosion.

MATERIAL AND METHODS

Bovine dentin specimens were allocated into four groups (n=10): control (no F), 1450ppm F (as NaF), 5000ppm F (as NaF) and 1450ppm F (1100ppm as stabilized SnF2 and 350ppm as NaF)/sodium hexamethaphosphate. The specimens were submitted to 6 daily cycles of erosion (0.3% v/v citric acid, pH=3.2, 20 min) and remineralization (~22h), interspersed by 2-min immersions in 1:3 w/v of dentifrice/distilled water slurries. Subsequently, they were subjected to a 24-h acid resistance test (0.3% v/v citric acid, pH=3.2) without any further treatments. Surface loss was quantified by contact profilometry. Data were analysed through one-way ANOVA and Bonferroni's tests (p≤0.05).

RESULTS

In both experiments, all fluoride groups, showed significantly less tissue loss compared to the control (p<0.001-p=0.018). During erosion cycling, no significant differences were found among the fluoride groups. During the acid resistance test, the 5000ppm F toothpaste produced significantly superior effect than both 1450ppm F products (p=0.010, (p<0.001), which performed similarly.

CONCLUSIONS

Under less aggressive erosive conditions, fluoride toothpastes did not differ in their ability to protect dentine surfaces. However, in severely erosive environment, the 5000ppm F toothpaste performed superiorly to the other tested products. Key words:Dentine, sodium fluoride, stannous fluoride, tooth erosion, toothpaste, contact profilometry.

Demineralization-remineralization dynamics in teeth and bone

Biomineralization is a dynamic, complex, lifelong process by which living organisms control precipitations of inorganic nanocrystals within organic matrices to form unique hybrid biological tissues, for example, enamel, dentin, cementum, and bone. Understanding the process of mineral deposition is important for the development of treatments for mineralization-related diseases and also for the innovation and development of scaffolds. This review provides a thorough overview of the up-to-date information on the theories describing the possible mechanisms and the factors implicated as agonists and antagonists of mineralization. Then, the role of calcium and phosphate ions in the maintenance of teeth and bone health is described. Throughout the life, teeth and bone are at risk of demineralization, with particular emphasis on teeth, due to their anatomical arrangement and location. Teeth are exposed to food, drink, and the microbiota of the mouth; therefore, they have developed a high resistance to localized demineralization that is unmatched by bone. The mechanisms by which demineralization-remineralization process occurs in both teeth and bone and the new therapies/technologies that reverse demineralization or boost remineralization are also scrupulously discussed. Technologies discussed include composites with nano- and micron-sized inorganic minerals that can mimic mechanical properties of the tooth and bone in addition to promoting more natural repair of surrounding tissues. Turning these new technologies to products and practices would improve health care worldwide.

Enamel lesions: Meta-analysis on effect of prophylactic/therapeutic agents in erosive tissue loss

This study aims to perform a meta-analysis on the effect of prophylactic/therapeutic agents in enamel tissue loss due to erosion. A paper search was done on Medline, PubMed, Embase, and Cochrane Library, and 732 papers were identified. The inclusion criteria were very restrictive in order to be able to compare different protocols and methodologies used on those studies. Sixteen papers were eligible, grouped according to the measurement method of enamel tissue loss, and a meta-analysis was done for each type of fluoride- and casein-based agent applied. Standardized mean differences were pooled across studies. There was a significant difference between all the treatment groups and their respective control groups. The highest standardized mean difference on enamel tissue loss (mean; 95% confidence interval) was obtained by stannous fluoride (4.789 μm; 1.968-7.610; P < 0.001), followed by amine fluoride (2.485 μm; 0.746-4.225; P < 0.010), and titanium tetrafluoride (1.787 μm; 1.106-2.469; P < 0.001); the lowest difference was obtained by casein phosphopeptide-amorphous calcium phosphate (0.869 μm; 0.007-1.731; P < 0.050) and sodium fluoride (0.820 μm; 0.417-1.223; P < 0.001). Stannous fluoride as a fluoride-based prophylactic/therapeutic agent allowed the lowest enamel tissue loss in erosive conditions. Standardization among future study protocols will allow better comparison regarding the prophylactic/therapeutic agent with the best clinical efficacy.

Erosion protection benefits of stabilized SnF2 dentifrice versus an arginine-sodium monofluorophosphate dentifrice: results from in vitro and in situ clinical studies

Objectives

The aim of these investigations was to assess the ability of two fluoride dentifrices to protect against the initiation and progression of dental erosion using a predictive in vitro erosion cycling model and a human in situ erosion prevention clinical trial for verification of effectiveness.

Materials and methods

A stabilized stannous fluoride (SnF₂) dentifrice (0.454 % SnF₂ + 0.077 % sodium fluoride [NaF]; total F = 1450 ppm F) [dentifrice A] and a sodium monofluorophosphate [SMFP]/arginine dentifrice (1.1 % SMFP + 1.5 % arginine; total F = 1450 ppm F) [dentifrice B] were tested in a 5-day in vitro erosion cycling model and a 10-day randomized, controlled, double-blind, two-treatment, four-period crossover in situ clinical trial. In each study, human enamel specimens were exposed to repetitive product treatments using a standardized dilution of test products followed by erosive acid challenges in a systematic fashion.

Results

Both studies demonstrated statistically significant differences between the two products, with dentifrice A providing significantly better enamel protection in each study. In vitro, dentifrice A provided a 75.8 % benefit over dentifrice B (p < 0.05, ANOVA), while after 10 days in the in situ model, dentifrice A provided 93.9 % greater protection versus dentifrice B (p < 0.0001, general linear mixed model).

Conclusion

These results support the superiority of stabilized SnF₂ dentifrices for protecting human teeth against the initiation and progression of dental erosion.

Clinical relevance

Stabilized SnF₂ dentifrices may provide more significant benefits to consumers than conventional fluoride dentifrices.

Influence of Bristle Stiffness of Manual Toothbrushes on Eroded and Sound Human Dentin--An In Vitro Study

Aim

The aim of this study was to determine the influence of manual toothbrushes with different bristle stiffness on the abrasivity on eroded and sound human dentin.

Materials and Methods

Dentin specimens were made from impacted third molars and attributed to three groups: erosion-abrasion (EA), abrasion (A) and erosion (E). The specimens from EA and E were treated with 1% citric acid (pH 2.3) for 1 min rinsed, and neutralized with artificial saliva for 15 min. This cycle was repeated five times. Thereafter, specimens from EA and A were treated with three toothbrushes types with different bristle stiffness (soft, medium, and hard) in a custom-made toothbrushing machine. The brushing was performed at a load of 3 N with a toothpaste slurry for 630 s. This procedure was repeated five times, in group EA after each erosion cycle. EA and A groups passed through five cycles with a total of 6300 strokes. The abrasivity was analyzed by contact-free profilometry. Kruskal-Wallis and Mann-Whitney U tests were performed for statistical analysis.

Results

With respect to bristle stiffness there was no statistically significant difference in dentin loss within the EA group. In group A, a statistically significantly higher dentin loss was found for the soft in comparison to the hard bristles. No statistically significant differences were measured between soft/medium and medium/hard toothbrushes. The amount of dentin loss from specimens in the EA group was significantly higher than in the A group.

Conclusions

Within the limitations of this study, the dentin loss in the Abrasion group was higher with soft bristles than with hard ones. This result might have an influence on the toothbrush recommendations for patients with non-carious cervical lesions.

Effects of polyphosphates and fluoride on hydroxyapatite dissolution: A pH-stat investigation

OBJECTIVES

This study investigated the immediate and sustained effect of sodium trimetaphosphate (TMP) and sodium hexametaphosphate (HMP) associated or not with fluoride (F) on hydroxyapatite (HA) dissolution using an erosion-like model, considering as well as the influence of salivary coating.

DESIGN

Baseline dissolution rates were determined for HA discs using a pH-stat system. In the first set of experiments, HA discs were treated with 1100μgF/mL, 1% or 8% of HMP, 1% or 8% of TMP and 1100μgF/mL associated with 1% or 8% of HMP or TMP, totaling 9 groups (n=8). In a second phase, HA discs were kept in pooled human saliva at 37°C for 2h before treatment with deionised water and 1100μgF/mL associated with 1% or 8% of HMP or TMP, totaling 5 groups (n=8). The post-treatment dissolution rate was determined from three consecutive 30-min assays. Data were analysed using 2 and 3-way ANOVA followed by Fisher and Holm-Sidak methods, respectively (α=0.05).

RESULTS

All test solutions promoted reduction in HA dissolution rate when compared to baseline control in the first post-treatment run (p<0.001). However, a synergistic effect was only observed between fluoride and 1% HMP. Moreover, the duration of inhibitory effect was greater when 8% HMP and 1 or 8% HMP associated with F were assessed (p<0.001). The presence of salivary coating led to higher protection for all groups when compared to discs without coating (p<0.001).

CONCLUSION

The reduction of HA dissolution rate, as well as the duration of this effect were influenced by fluoride, type and concentration of phosphate salt and the presence of a salivary coating.

A randomised clinical study to measure the anti-erosion benefits of a stannous-containing sodium fluoride dentifrice

Background:

To compare the enamel protection efficacy of stannous-containing sodium fluoride and sodium monofluorophosphate (MFP)/triclosan dentifrices marketed in India in an in situ erosion model with acidic challenge.

Materials and Methods:

This randomised and controlled, in situ, supervised, double-blind clinical trial employed a two-treatment, four-period crossover design, wherein subjects wore an appliance fitted with human enamel samples 6 h/day during each 10 day treatment period and swished twice daily with their assigned dentifrice slurry: Oral-B^® Pro-Health (maximum 1,000 ppm F as sodium fluoride with stannous chloride) or Colgate^® Strong Teeth with Cavity Protection (maximum 1,000 F as sodium MFP and triclosan). Subjects swished with 250 ml of orange juice over a 10 min period after each treatment and twice daily for the acidic erosive challenge. Enamel samples were measured for tooth surface loss using contact profilometry at baseline and day 10.

Results:

A total of 34 subjects were randomised to treatment; 32 subjects completed the final visit. Baseline profilometry measurements of the specimen surfaces were near zero within ± 0.3 μm, and no statistically significant difference (P > 0.48) on average was observed between the two test dentifrices. At day 10, the stannous-containing dentifrice demonstrated 88% less erosion (P < 0.0001) relative to the MFP/triclosan dentifrice. Estimated medians (95% confidence intervals) were 0.21 μm (0.17, 0.25) for the stannous-containing dentifrice versus 1.66 μm (1.39, 1.99) for the MFP/triclosan dentifrice. Both dentifrices were well-tolerated.

Conclusions:

Compared with MFP/triclosan toothpaste, a stabilised stannous-containing sodium fluoride dentifrice gave statistically significantly greater protection against tooth enamel surface loss in situ following repeated acid erosive challenge.

The Future of Fluorides and Other Protective Agents in Erosion Prevention

The effectiveness of fluoride in caries prevention has been convincingly proven. In recent years, researchers have investigated the preventive effects of different fluoride formulations on erosive tooth wear with positive results, but their action on caries and erosion prevention must be based on different requirements, because there is no sheltered area in the erosive process as there is in the subsurface carious lesions. Thus, any protective mechanism from fluoride concerning erosion is limited to the surface or the near surface layer of enamel. However, reports on other protective agents show superior preventive results. The mechanism of action of tin-containing products is related to tin deposition onto the tooth surface, as well as the incorporation of tin into the near-surface layer of enamel. These tin-rich deposits are less susceptible to dissolution and may result in enhanced protection of the underlying tooth. Titanium tetrafluoride forms a protective layer on the tooth surface. It is believed that this layer is made up of hydrated hydrogen titanium phosphate. Products containing phosphates and/or proteins may adsorb either to the pellicle, rendering it more protective against demineralization, or directly to the dental hard tissue, probably competing with H+ at specific sites on the tooth surface. Other substances may further enhance precipitation of calcium phosphates on the enamel surface, protecting it from additional acid impacts. Hence, the future of fluoride alone in erosion prevention looks grim, but the combination of fluoride with protective agents, such as polyvalent metal ions and some polymers, has much brighter prospects.

Clinical enamel surface changes following an intra-oral acidic challenge

OBJECTIVES

Investigation of early enamel erosion using replica impressions to compare changes in enamel surface topography in vivo prior to and over a 24 h period following acid challenge.

METHOD

A single treatment, blinded, enamel replica clinical study was undertaken in 20 healthy subjects. Replica tooth impressions were taken at baseline, following acid challenge and 2, 4, 7 and 24 h post challenge. Subjects consumed 500 ml of acidic soft drink over 30 min. Scanning electron microscopy of surface tomography was characterised with a descriptive 5 point scale by four judges. Duplicate impressions were taken to assess reproducibility.

RESULTS

18 subjects had scorable sequences. Descriptive analyses showed erosive changes following acid consumption and reparative changes in the subsequent 24 h period. Comparing baseline replica to the 24 h replica, there were no significant differences (p=0.26) in tooth surface characteristics. Comparing the replica taken immediately following acidic challenge with the subsequent replicas at 2, 4, 7 and 24 h, showed clear reduction of erosive effects on the enamel surface at 2 h (p=0.02) and a highly significant reduction at 4, 7 and 24 h (p<0.001).

CONCLUSION

This methodology demonstrated the ability to follow the progression and recovery of early erosive enamel lesions over 24 h being accurate and reproducible. This study suggests enamel repair commences within 2 h following a substantial acidic challenge and is completed 4-24 h later. After 24 h, the tooth surface appeared visibly indistinguishable from the original tooth surface, suggestive of a recovery process occurring.

CLINICAL SIGNIFICANCE

Healthy erosive lifestyles often culminate in tooth wear. The time taken for enamel remineralisation following acidic challenge is unknown however, this study suggests the repair process is relatively slow following a substantial acidic challenge, and at least 4-24 h should elapse prior to further acidic consumption to allow for recovery.

May caries-preventive fluoride regimes have an effect on dental erosive wear? An in situ study

OBJECTIVE

High and low concentration NaF regimes have shown caries protective properties, but the preventive effect against erosive/abrasive wear is unclear. AIM. To measure the inhibiting effect on enamel wear of low and highly concentrated sodium fluoride (NaF) toothpastes and a stannous (SnF2) fluoride gel in a single-blind, randomized in situ study, using a White Light Interferometer.

MATERIALS AND METHODS

Sixteen human molars were each divided into four specimens, mounted on acrylic mouth appliances and worn by eight volunteers for 9 days. Experimental procedures were performed in the laboratory. The enamel specimens were brushed every day with fluoride-free toothpaste. Treatments; group 1: no fluoride treatment (control), group 2: SnF2 gel 2500 ppm F (5 min) every third day, group 3: NaF toothpaste 5000 ppm F 5 min every third day and 2 min the other days, group 4: NaF toothpaste 1450 ppm F (2 min) every day. In order to mimic gastric reflux/vomiting, the specimens were etched with 0.01 M HCl for 2 min twice a day.

RESULTS

The mean step height (µm) for the control specimens was -32.9 (SD = 6.8). The mean values for the other groups were -22.2 (SD = 8.4) (group 2), -30.8 (SD = 7.8) (group 3) and -31.4 (SD = 7.7) (group 4). Compared with the control, the SnF2 treated specimens showed significantly lower wear. The NaF toothpastes gave no significant protective effect.

CONCLUSIONS

Application of SnF2 gel every third day gave protection against erosive-abrasive challenges. Daily application of both low concentration and high concentration NaF toothpaste provided no protection.

Preventive effect of a high fluoride toothpaste and arginine-carbonate toothpaste on dentinal tubules exposure followed by acid challenge: a dentine permeability evaluation

Background

Considering the current high use of high fluoride toothpastes, the aim of the study was to quantify alterations in the root dentine permeability submitted to treatment with a high fluoride toothpaste and 8% arginine, calcium carbonate, sodium monofluorophosphate toothpaste as a preventive treatment for dentinal tubules exposure followed by acid challenge.

Methods

Thirty-third molars were sectioned below the cementoenamel. The root segments were connected to a hydraulic pressure apparatus to measure dentine permeability after the following sequential steps (n = 10 per group): I) Baseline; II) treatment with phosphoric acid for 30 s (maximum permeability); III) Toothbrushing (1 min) according to the experimental groups (G1- control; G2- 5000 ppm fluoride toothpaste; G3- 8% arginine-calcium carbonate toothpaste); IV) acid challenge for 5 min (orange juice). The data were converted into percentage, considering stage II as 100%.

Results

The results have shown a statistically significant decreasing on dentine permeability after treatment with toothpaste (Friedman test and Dunn’s post hoc test). Comparison among groups demonstrated a high increasing on dentine permeability when acid challenge was performed after toothbrushing with distilled water (control group) (Kruskal-Wallis and Dunn’s post hoc test).

Conclusion

The toothpaste treatment may provide sufficient resistance on dentine surface, preventing dentinal tubules exposure after acid challenge.

Protective effects of SnF2 - Part I. Mineral solubilisation studies on powdered apatite

PURPOSE

To compare the ability of two active ingredients - sodium fluoride (NaF) and stannous fluoride (SnF2 ) - to inhibit hydroxyapatite (HAP) dissolution in buffered acidic media.

METHODS

Two in vitro studies were conducted. HAP powder, which is representative of tooth mineral, was pretreated with: test solutions of NaF or SnF2 , 10 g solution per 300 mg HAP powder (Study 1); or NaF or SnF2 dentifrice slurry supernatants, 20 g supernate per 200 mg HAP powder for 1 minute followed by three washes with water, then dried (Study 2). About 50 mg of pretreated HAP was exposed to 25 ml of acid dissolution media adjusted to and maintained at pH 4.5 in a Metrohn Titrino reaction cell. Exposure of HAP to the media results in dissolution and release of hydroxide ion, increasing the pH of the solution. The increase in pH is compensated for by automatic additions of acid to maintain the original pH (4.5) of the reaction cell. Total volume of titrant added after 30 minutes was used to calculate the percentage reduction in dissolution versus non-treated HAP control.

RESULTS

Both F sources provided protection against acid dissolution; however, in each study, SnF2 -treated HAP was significantly more acid-resistant than the NaF treated mineral. In study 1, at 280 ppm F, representing concentrations of F found in the mouth after in vivo dentifrice use, the reduction in HAP dissolution was 47.7% for NaF and 75.7% for the SnF2 -treated apatite (extrapolated). In study 2, the reduction in HAP dissolution was 61.3% for NaF and 92.8% for SnF2 -treated samples. Differences in percentage reduction were statistically significant (Paired-t test).

CONCLUSIONS

Results of these studies demonstrate that both of the fluoride sources tested enhance the acid resistance of tooth mineral and that resistance is significantly greater after treatment with SnF2 compared with treatment of tooth mineral with NaF.

Protective effects of SnF2 - Part III. Mechanism of barrier layer attachment

OBJECTIVE

To assess the ability of various fluoride salts to protect enamel against acid attack via a barrier mechanism.

METHODS

Extracted human enamel specimens were cleaned and rinsed, then soaked in pooled human saliva for 1 hour to initiate formation of an early pellicle. Groups of three specimens each were etched for 10 minutes in 1% citric acid (pH 2.3), treated in a 1:3 slurry of dentifrice [1,100 ppm F as stannous fluoride (SnF2 ), 1,100 ppm F as sodium fluoride (NaF), 1,000 ppm F as sodium monofluorophosphate (SMFP), or 1,400 ppm F as amine fluoride (AmF)] and saliva for 2 minutes, exposed to 2% alizarin red-S (a calcium-selective dye) and rinsed again. The relative ability of each test product to deposit a barrier layer on the enamel surface was measured by its ability to protect against attachment of the calcium-selective dye.

RESULTS

Specimens treated with the SnF2 dentifrice showed the least dye attachment, indicating a high level of surface protection. On a five-point scale, with 0 being no dye deposition (100% protection) and four being complete dye coverage (0% protection), the SnF2 -treated specimens scored an average of 0.25, with NaF scoring 3.4, SMFP scoring 3.4 and AmF scoring 3.7. Protection of the enamel surface was significantly higher for the SnF2 product than for the other products (P < 0.05), with no significant differences among the other three F salts.

CONCLUSIONS

These results demonstrate that after an aggressive acid challenge, SnF2 deposits a barrier layer onto the pellicle-coated enamel surface, and the barrier layer which attaches onto acid challenged tooth surfaces is different from any that might be provided by treatment with the other fluoride compounds tested.

A randomised in situ trial, measuring the anti-erosive properties of a stannous-containing sodium fluoride dentifrice compared with a sodium fluoride/potassium nitrate dentifrice

OBJECTIVES

To determine if a stabilised, stannous-containing sodium fluoride dentifrice provides greater enamel protection in situ against intraoral dietary erosive challenges compared with a sodium fluoride/potassium nitrate dentifrice.

METHODS

A single-centre, investigator blind, randomised, supervised, two-treatment, non-brushing, four-period crossover in situ study was undertaken, with each test period being 15 days. Thirty-five healthy adult subjects were recruited to participate in the study, which included four erosive acid challenges per day. Subjects were randomised to product treatment, which included either: (1) a stannous-containing sodium fluoride dentifrice (Oral-B(®) Pro-Expert Sensitive) or (2) a sodium fluoride/potassium nitrate dentifrice (Sensodyne(®) Pronamel(®) ). Each study subject wore an intraoral appliance retaining two sterilised, polished human enamel samples for 6 hours/day. Subjects swished with an allocated dentifrice slurry twice a day and with 250 ml of orange juice for 10 minutes (25 ml/minute over a 10-minute period) four times per day. The primary and secondary outcomes for this study were enamel loss measured using contact profilometry at days 15 and 5, respectively, using parametric analysis methods.

RESULTS

At day 15, a 38% lower enamel loss (P < 0.0001) was observed, with estimated medians of 2.03 μm (SE 0.247) and 3.30 μm (SE 0.379), in favour of the stannous-containing dentifrice. At day 5, specimens treated with the stannous-containing sodium fluoride dentifrice demonstrated 25% less enamel loss than those treated with the sodium fluoride/potassium nitrate dentifrice. Treatment differences at day 5 were also statistically significant (P < 0.05), with estimated medians of 1.37 μm (SE 0.177) and 1.83 μm (SE 0.223), respectively.

CONCLUSIONS

Results of this in situ study suggest the stabilised, stannous-containing sodium fluoride dentifrice could be used to provide significantly greater protection to enamel from erosive acid challenge compared with that provided by conventional fluoride-containing products.

Protective effects of SnF2 - Part II. Deposition and retention on pellicle-coated enamel

Deposition of an acid-resistant barrier onto enamel represents a potentially superior means for delivering protection against dietary, erosive acid challenges.

PURPOSE

The purpose of this study was to demonstrate the ability of a stabilised stannous fluoride (SnF2 ) dentifrice to: (1) deposit a SnF2 barrier layer onto pellicle-coated enamel surfaces; (2) increase the intensity of the barrier layer over time; and (3) be retained on the enamel surface for hours after product use.

METHODS

Squares of human enamel were exposed to pooled saliva for 1 hour (pellicle formation) and separated into six sets. Set 1 was treated with the supernatant of a 1:3 slurry of the test dentifrice (Crest(®) Pro-Health(®) : water for 2 minutes), then rinsed. Set 2 was treated in the same manner and then placed into saliva (6 hours). Set 3 was cycled through seven repeated treatments. Set 4 was treated for seven cycles and then placed into saliva (6 hours). Set 5 was a water control, and set 6 was a water control that remained in saliva for 6 hours. Surface analysis of specimens was done using laser ablation Inductively Coupled Plasma Mass Spectroscopy (ICP-MS).

RESULTS

Deposition of a barrier layer was demonstrated, beginning with the initial treatment, with Sn (using isotopes (117) Sn + (120) Sn) measured on the enamel surface as the reference marker. Deposition of the barrier layer was greater after seven cycles, and the retention of this layer was highly significant (P = 0.05, anova: 6 hours).

CONCLUSIONS

This study confirms that: (1) the stabilised SnF2 dentifrice deposits a barrier layer onto the enamel surface, beginning with the first use of the product; (2) this barrier is enhanced following multiple treatments; and (3) the barrier layer is retained on the enamel surface for hours after product use.