Comparative Evaluation of the Remineralization Potential of Fluoride-containing Toothpaste, Honey Ginger Paste and Ozone. An In Vitro Study

Introduction

A drop in pH of the oral cavity results in demineralization, which, if continued, leads to loss of minerals from tooth structure, resulting in dental caries. A goal of modern dentistry is to manage noncavitated caries lesions noninvasively through remineralization in an attempt to prevent disease progression.

Materials and methods

A total of 40 extracted premolar teeth were selected for the study. The specimens were divided into four groups, group I, the control group; group II, remineralizing agent as fluoride toothpaste; group III, the treatment material as ginger and honey paste; and group IV, the treatment material as ozone oil. An initial reading of surface roughness and hardness was recorded for the group (control group). Repeated treatment has continued lasting 21 days. This saliva was changed each day. Following the lesion formation procedure, the surface microhardness was measured for all specimens. The parameters were 200 gm force for 15 seconds with a Vickers indenter and the roughness of the demineralized area of each specimen was obtained by using the surface roughness tester.

Results

Surface roughness was checked by using a surface roughness tester. Before starting the pH cycle, the baseline value for the control group was calculated. The baseline value for the control group was calculated. The surface roughness average value for 10 samples is 0.555 µm and the average surface microhardness is 304 HV; the average surface roughness value for fluoride is 0.244 µm and the microhardness is 256 HV, 0.241 µm, and 271 HV value for honey-ginger paste. For ozone surface roughness average value is 0.238 µm and the surface microhardness average mean value is 253 HV.

Conclusion

The future of dentistry will rely on the regeneration of tooth structure. There is no significant difference seen between each treatment group. Considering the adverse effect of fluoride, we can consider honey-ginger and ozone as good remineralizing agents for fluoride.

How to cite this article

Kade KK, Chaudhary S, Shah R, et al. Comparative Evaluation of the Remineralization Potential of Fluoride-containing Toothpaste, Honey Ginger Paste and Ozone. An In Vitro Study. Int J Clin Pediatr Dent 2022;15(5):541-548.

Erosive loss of tooth substance is dependent on enamel surface structure and presence of pellicle - An in vitro study

OBJECTIVE

Aim of this in vitro study was to investigate erosive tooth loss in dependence of the enamel surface structure and presence of an acquired pellicle.

METHODS

Enamel specimens from 19 bovine incisors (4 specimens/incisor) were allocated to four experimental groups (n = 19). The surfaces of half of the specimens were polished (two groups), while the other half was left native (two groups). Specimens of one polished and one native group were placed in pooled human saliva (30 min) for the formation of an acquired pellicle. Thereafter, all specimens were demineralized by superfusion with hydrochloric acid (17 min, pH 2.3) with collection of the superfluent. Erosive substance loss was determined by measuring the dissolved calcium content using a colorimetric assay with Arsenazo III reagent. Differences in erosive substance loss were statistically analyzed with respect to enamel surface and pellicle. A linear mixed effects model was fitted to the data and pairwise differences between groups were evaluated (significance level α= 0.05).

RESULTS

Enamel surface structure (p < 0.001) and presence of pellicle (p = 0.01) had a significant effect on erosive substance loss. Polished surfaces with pellicle showed the lowest cumulative calcium release [nmol Ca/mm²] (means ± standard deviation: 48+/-5), followed by polished specimens without (51+/-9) and native specimens with pellicle (54+/-10). No significant differences were found between these groups. Highest cumulative calcium release was found for native specimens without pellicle (61+/-9; p < 0.05).

CONCLUSIONS

Both enamel surface structure and the acquired pellicle are important determinants of the susceptibility to erosive tooth loss.

Bonding durability of titanium tetrafluoride treated glass fiber post with resin cement

This study evaluated the effect of titanium tetrafluoride (TiF₄) solution on the bond strength of glass fiber post to resin cement. The specimens were divided into eight groups according to the method of surface treatment performed. Flexural properties and microtensile bond strength (µTBS) were determined. Data were analyzed using two-way ANOVA and Tukey's post hoc tests. The highest µTBS achieved with the TiF₄ (4 wt/v%-4 min) group compared with the other groups (p<0.05). This finding could be attributed to the effectiveness of TiF₄ (4 wt/v%-4 min) on removing the surface layer of the resin matrix of fiber posts that provides more uncovered surface areas of posts which improved the micromechanical retention of the resin cement. Surface treatments did not affect the flexural properties of fiber posts (p>0.05). Surface treatment of fiber post with TiF₄ (4 wt/v%-4 min) solution exhibited higher bond strength to resin cement compared with other surface treatments.

Effect of Phosphorylated Chitosan on Dentin Erosion: An in vitro Study

The aim of this study was to evaluate the antierosive effect of phosphorylated chitosan in dentin. Bovine dentin specimens were randomly distributed into the following groups: (1) no treatment (NoTx/negative control), (2) phosphate-buffered saline solution (PBS), (3) AmF/NaF/SnCl2 (positive control), (4) 0.5% chitosan solution (Chi), (5) 0.5% neutral phosphorylated (NP)-Chi, and (6) 0.5% alkaline phosphorylated (AP)-Chi. The specimens were submitted to de-remineralization treatment cycles for 5 days: 0.5% citric acid (2 min), remineralizing solution (30 min), and surface treatment according to assigned groups (2 min, 6×/day). The loss of dentin surface was measured by profilometry. Hardness and modulus of elasticity were measured using a nanoindenter equipped with a Berkovich diamond tip. The dentin surface was analyzed by scanning electron microscopy (SEM). The largest loss of dentin was observed in the No Tx and PBS groups (approx. 25 µm). The group treated with AmF/NaF/SnCl2 showed less loss of dentin (67% reduction vs. NoTx and PBS), followed by the groups treated with NP-Chi and AP-Chi (33% reduction), and Chi (18% reduction). Nanohardness and modulus of elasticity were similar in the NoTx and PBS groups, with a small increase in stiffness in all other groups. SEM revealed that the experimental solution of AP-Chi had a favorable effect on maintaining the integrity of collagen fibrils. AmF/NaF/SnCl2 showed a preserved mineralized collagen surface. Further studies are warranted to explore this nontoxic phosphorylated chitosan polymer as an effective agent in the prevention and treatment of dental erosion.

Comparative evaluation of microhardness of dentin treated with 4% titanium tetrafluoride and 1.23% acidic phosphate fluoride gel before and after exposure to acidic pH: An ex vivo study

AIM

The aim of this study was to comparatively evaluate the effect of 4% titanium tetrafluoride (TiF4) and 1.23% acidic phosphate fluoride (APF) gel on the microhardness of human coronal dentin.

MATERIALS AND METHODS

Thirty noncarious extracted premolars were collected and sectioned buccolingually with the help of diamond disk. Exposing the sectioned surface, teeth were embedded in self-cure acrylic. Exposed coronal dentin was polished with abrasive papers starting with 220-5000 grit. Microhardness was evaluated by Vickers microhardness evaluator, at four different stages as follows - stage 1: Baseline values, Stage 2: Exposure of specimens to acidic environment at a pH 1 for 5 min, Stage 3: Application of 1.23% APF gel and 4% TiF4 (after dividing the specimens into two groups, i.e., Group A and B, respectively), and Stage 4: Followed by exposure of fluoridated specimens to acidic protocol as mentioned above.

RESULTS

Paired t-test was used to compare the readings between Groups A and B. Group B has shown greater resistance to decrease in microhardness of coronal dentin (P < 0.05) on exposure to acidic protocol.

CONCLUSION

Due to acidic pH (1.5) of 4% TiF4, amount of increase in microhardness of dentin is <1.23% APF gel. 4% TiF4 was more effective in resisting demineralization than 1.23% APF gel.

Role of TiF4 in Microleakage of Silorane and Methacrylate-based Composite Resins in Class V Cavities

AIM

This study investigated the effect of TiF4 solution pretreat-ment on microleakage of silorane and nanofilled methacrylate-based composites in class V cavities.

MATERIALS AND METHODS

Forty-eight intact premolar teeth were randomly allocated to four groups of 12 teeth. Restorative techniques after standard class V tooth preparations were as follows: Group 1, Filtek P90 composite; group 2, Filtek Z350 XT; group 3, TiF4 solution pretreatment and Filtek P90 composite; group 4, TiF4 solution pretreatment and Filtek Z350 XT. After storing the specimens in distilled water at 37°C for 24 hours and followed by immersion of the specimens in a 0.5% basic-fuchsin solution for 24 hours, they were sectioned buccolingually to obtain four surfaces for each specimen for analysis of microleakage using a stereomicroscope. Data analysis was performed using Kruskal-Wallis test to compare the four groups and the Mann-Whitney test for paired comparisons with Statistical Package for the Social Sciences (SPSS) version 17 software.

RESULTS

At the enamel margins, microleakage score of the Filtek Z350 XT group was lower than those of the Filtek P90 with and without the application of the TiF4 (p = 0.009 and p = 0.031 respectively). At the dentin margins, groups 3 and 4 (TiF4+Filtek P90 and TiF4+Filtek z350 XT respectively) showed significantly lower microleakage than group 1 (Filtek P90). However, there was no significant difference between other groups (p > 0.05).

CONCLUSION

At the enamel margins, microleakage score of the silorane-based composite was more than that of the nanofilled composite. No significant differences were observed between the other groups. At the dentin margins, for the silorane-based composite restorations, TiF4 solution pretreatment resulted in significantly lower microleakage. However, the similar result was not observed for Filtek Z350 XT. Also, no significant difference was observed between microleakage scores of Filtek P90 and Filtek Z350 XT with or without TiF4 pretreatment.

CLINICAL SIGNIFICANCE

In spite of better mechanical and physical properties of modern composites than earlier methacrylate-based composites, polymerization shrinkage has been remaining as one of the main shortcomings of them. Different methods, such as using new low shrinkage resin composites and different dentin pretreatments, have been suggested to overcome this problem. This study evaluated the effect of TiF4 as pretreatment on microleakage of class V tooth preparations restored with a nanocomposite and a silorane-based resin composite.

Artificial Saliva Formulations versus Human Saliva Pretreatment in Dental Erosion Experiments

The aim of this study was to evaluate the erosion-preventive effect of different artificial saliva formulations and human saliva in vitro compared to human saliva in situ. In the in vitro experiment, bovine enamel and dentin specimens were stored in artificial saliva (4 different formulations, each n = 20), deionized water (n = 20) or human saliva (n = 6 enamel and dentin specimens/volunteer) for 120 min. In the in situ experiment, each of the 6 enamel and dentin specimens was worn intraorally by 10 volunteers for 120 min. The specimens were then eroded (HCl, pH 2.6, 60 s). Half of the specimens were subjected to microhardness analysis (enamel) and the determination of calcium release into the acid (enamel and dentin), while the other half were again placed in the respective medium or worn intraorally, respectively, for 120 min before a second erosion was performed. Knoop microhardness of enamel and the calcium release of enamel and dentin into the acid were again determined. Statistical analysis was conducted by two-way repeated-measures ANOVA or two-way ANOVA (α = 0.05). Enamel microhardness was not significantly different between all test groups after the first and the second erosive challenge, respectively. Enamel calcium loss was significantly lower in situ compared to the in vitro experiment, where there was no significant difference between all test groups. Dentin calcium loss was significantly lower than deionized water only after the first and than all except one artificial saliva after the second erosion. Under the conditions of this experiment, the use of artificial saliva formulations and human saliva in vitro does not reflect the intraoral situation in dental erosion experiments adequately.

Comparative In Vitro Effect of TiF4 to NaF and Potassium Oxalate on Reduction of Dentin Hydraulic Conductance

Dentin hypersensitivity (DH) is related to an increase in dentin permeability. This study tested the effect of titanium tetrafluoride (TiF4) compared with sodium fluoride (NaF) and potassium oxalate gel on reducing hydraulic conductance (Lp) from the perspective of diminishing dentin permeability. The Lp of the dentin disks (1.0 ± 0.2 mm) was evaluated using Flodec. The maximum Lp values of each disk were taken after phosphoric acid etching (15 seconds) and randomly allocated to seven groups (n=8) according to the treatments. The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Treatments were performed for 4 minutes as follows: 1) NaF varnish 2) and solution (2.45% F, pH 5.0), 3) TiF4 varnish and 4) solution (2.45% F, pH 1.0), 5) 3% potassium oxalate gel, 6) free fluoride varnish (placebo, pH 5.0), 7) and no treatment (control). The Lp after each treatment was assessed. Samples were exposed to an erosive challenge (6% citric acid, pH 2.1, 1 minute), and the final Lp was recorded. The data were statistically analyzed using repeated measures two-way analysis of variance (p&lt;0.05). All treatments were effective in reducing dentin Lp compared with the control immediately after the application. However, only potassium oxalate and NaF varnish significantly differed from placebo varnish (p&lt;0.0001). The same results were found after the erosive challenge. Therefore, the TiF4 was less effective than the NaF varnish and potassium oxalate gel in reducing dentin permeability. Using this experimental model, both NaF varnish and potassium oxalate gel reduced the Lp similarly to the presence of smear layer.

The effect of casein phosphopeptide-amorphous calcium phosphate paste and sodium fluoride mouthwash on the prevention of dentine erosion: An in vitro study

Aim:

The purpose was to compare the effect of 0.2% sodium fluoride mouthwash and casein phosphopeptide-amorphous calcium phosphate paste on prevention of dentin erosion.

Materials and Methods:

Buccal surfaces of 36 sound premolar teeth were ground flat and polished with abrasive discs. Half the polished surfaces were covered with tape to maintain a reference surface. Samples were randomly allocated into three groups. Group A was pretreated with tooth mousse (TM) 4 times a day for 5 days. Group B was pretreated with 0.2% sodium fluoride mouthwash 4 times a day for 5 days. Group C was considered as the control group with no pretreatment. In the next step, the samples were exposed to Coca-Cola 4 times a day for 3 days. After each erosive cycle, the samples were rinsed with deionized water and stored in artificial saliva. The surface loss was determined using profilometry.

Results:

The erosion in both Groups A and B was less than the control group. The surface loss in mouthwash group was significantly lower than in the control group. Erosion in TM group was more than the mouthwash group and less than the control group.

Conclusion:

Sodium fluoride mouthwash is more effective for prevention of dentin erosion.

Stability against brushing abrasion and the erosion-protective effect of different fluoride compounds

This study aimed to analyse the impact of brushing on the protective effect of different fluoride solutions on enamel and dentin erosion. Bovine enamel and dentin specimens were rinsed once with TiF4, AmF, SnF2 (0.5 M F, 2 min) or water (control). Specimens were either left unbrushed or brushed with 10, 20, 50, 100 or 500 brushing strokes in an automatic brushing machine (2 N, non-fluoridated toothpaste slurry). Ten specimens per group were eroded with hydrochloric acid (HCl) (pH 2.3) for 60 s, and calcium release into the acid was determined by atomic absorption spectroscopy. Additionally, enamel and dentin surfaces were analysed by X-ray energy-dispersive spectroscopy (EDS) (n = 6/group) and scanning electron microscopy (SEM) (n = 2/group) before brushing and after 500 brushing strokes. Statistical analysis (p < 0.05) was performed by three- and one-way ANOVA (calcium release) or repeated measures ANOVA (EDS). TiF4, AmF and SnF2 reduced the erosive calcium loss in unbrushed specimens to 58-67% (enamel) and 23-31% (dentin) of control. Calcium release increased with increasing brushing strokes prior to erosion and amounted to 70-88% (enamel) and 45-78% (dentin) of control after 500 brushing strokes. Brushing reduced the surface concentration of fluoride (AmF), tin (SnF2) and titanium (TiF4). SEM revealed that surface precipitates were affected by long-term brushing. Brushing reduced the protective potential of TiF4, AmF and SnF2 solutions. However, considering a small number of brushing strokes, the protective effect of fluoride solutions is only slightly affected by brushing abrasion.

Durability of the anti-erosive effect of surfaces sealants under erosive abrasive conditions

OBJECTIVE

To test the durability of sealants applied for prevention of erosive dentine mineral loss under erosive/abrasive conditions.

METHODS

Forty-eight bovine dentine samples doped with (32)P were randomly allocated to four groups (1-4). All samples performed a de- and remineralizations pre-cycling (6 × 1 min erosion in HCl: pH 3.0, mean time and overnight immersion in artificial saliva) for 1 day. Sealing was done as follows; (1) unsealed, (2) Seal & Protect, (3) K-0184 (experimental sealer) and (4) OptiBond FL. After sealing, samples were immersed in HCl for 3 h (baseline measurement). Then, the following erosive/abrasive and remineralisations cycling was performed for 8 days: 3 h/day erosion with HCl, 600 brushing strokes/day and storage in artificial saliva for the rest of the day. Sealer permeability was evaluated by assignation of (32)P in the acid used for the erosive attacks.

RESULTS

At baseline, the significantly highest dentine loss was observed for the unsealed control group, while the mineral loss was not statistically significantly different between the sealed groups 2 and 3. At all days of the erosive/abrasive and remineralizations cycling and cumulatively the significantly highest mineral loss was observed for group 1, while the significantly lowest mineral loss was observed for the samples sealed with Seal & Protect (group 2) and K-0184 (group 3). In all groups, no significant increase in the (32)P release was observed.

CONCLUSION

Surface sealants are able to reduce the erosive dentine mineral loss and maintain this erosion-preventing efficacy over the whole duration (simulating 8 month in-vivo) of the erosive/abrasive cycling.

Influence of prophylaxis paste treatment on the abrasive wear of surface sealants

OBJECTIVE

To investigate the abrasive wear of surface sealants (Seal&Protect and K-0184 (experimental sealant)) and the influence of pre-treatment with mineral deposit forming prophylaxis pastes (NUPRO Sensodyne and NUPRO) on this wear.

METHODS

One hundred and eight bovine dentine samples were randomly allocated to nine groups (1-9). Pre-treatment (10 s): groups 1-3: untreated, groups 4-6: NUPRO, groups 7-9: NUPRO Sensodyne. Sealing: groups 1, 4 and 7: unsealed, groups 2, 5 and 8: Seal&Protect, groups 3, 6 and 9: K-0184 (experimental sealer). Samples were then brushed with 12 000 brushing strokes (BS) with toothpaste slurry in an automatic brushing machine (120 BS/min; F = 2.5 N). Surface profiles were recorded at baseline, after pre-treatment and sealing and after each 2000 BS.

RESULTS

Total profile change (wear or gain due to pre-treatment, treatment and 12 000 BS): groups 1, 4 and 7 (no surface sealant) showed a not significantly different wear of 18.48 ± 2.63 µm, 24.98 ± 3.02 µm and 21.50 ± 5.47 µm, respectively. Remaining groups (sealed) showed a gain in height with no significant difference among each other. Wear in sealed groups (2, 3, 5, 6, 8 and 9) were not significantly different at all numbers of brushing strokes. Starting with 4000 BS, the wear in unsealed groups (1, 4 and 7) was statistically significantly higher compared to all other groups.

CONCLUSION

Stability and wear resistance of surface sealants are not affected by pre-treatment of dentine with NUPRO Sensodyne. The surface sealants tested provide a stable protective surface layer on dentine, which lasts for at least 12 000 brushing strokes.

Impact of laminar flow velocity of different acids on enamel calcium loss

OBJECTIVE

The aim of the study was to evaluate the impact of flow velocity under laminar flow conditions of different acidic solutions on enamel erosion.

MATERIAL AND METHODS

A total of 240 bovine enamel specimens were prepared and allocated to 30 groups (n = 8 each). Samples of 18 groups were superfused in a flow chamber system with laminar flow behavior using 1 ml of citric acid or hydrochloric acid (HCl) of pH 2.0, 2.6 or 3.0. Flow rates in the sample chamber were adjusted to 10, 60 or 100 μl/min. To simulate turbulent flow behavior, samples of six groups were immersed in 1 ml of the respective solution, which was vortexed (15 min, 600 rpm). For simulating non-agitated conditions, specimens of the remaining six groups were immersed in 1 ml of the respective solution without stirring. Calcium in the solutions, released from the enamel samples, was determined using Arsenazo III method.

RESULTS

For acidic solutions of pH 2.6 and 3.0, erosive potential of citric acid was equivalent to that of HCl at a flow of 100 μl/min. The same observation was made for the samples subjected to turbulent conditions at pH 3. At all other conditions, citric acid induced a significantly higher calcium loss than HCl.

CONCLUSION

It is concluded that under slow laminar flow conditions, flow rate variations lead to higher erosive impact of citric acid compared to hydrochloric acid at pH 2.0, but not at pH ≥ 2.6 and increasing laminar flow or turbulent conditions.

CLINICAL RELEVANCE

Erosive enamel dissolution under laminar flow conditions is a complex issue influenced by flow rate and acidic substrate.

Screening of CO(2) laser (10.6 μm) parameters for prevention of enamel erosion

OBJECTIVE

The aim of this study was to screen CO(2) laser (10.6 μm) parameters to increase enamel resistance to a continuous-flow erosive challenge.

BACKGROUND DATA

A new clinical CO(2) laser providing pulses of hundreds of microseconds, a range known to increase tooth acid-resistance, has been introduced in the market.

METHODS

Different laser parameters were tested in 12 groups (n=20) with varying fluences from 0.1 to 0.9 J/cm(2), pulse durations from 80 to 400 μs and repetition rates from 180 to 700 Hz. Non-lased samples (n=30) served as controls. All samples were eroded by exposure to hydrochloric acid (pH 2.6) under continuous acid flow (60 μL/min). Calcium and phosphate release into acid was monitored colorimetrically at 30 sec intervals up to 5 min and at 1 min intervals up to a total erosion time of 15 min. Scanning electron microscopic (SEM) analysis was performed in lased samples (n=3). Data were statistically analysed by one-way ANOVA (p<0.05) and Dunnett's post-hoc tests.

RESULTS

Calcium and phosphate release were significantly reduced by a maximum of 20% over time in samples irradiated with 0.4 J/cm(2) (200μs) at 450 Hz. Short-time reduction of calcium loss (≤1.5 min) could be also achieved by irradiation with 0.7 J/cm(2) (300μs) at 200 and 300 Hz. Both parameters revealed surface modification.

CONCLUSIONS

A set of CO(2) laser parameters was found that could significantly reduce enamel mineral loss (20%) under in vitro erosive conditions. However, as all parameters also caused surface cracking, they are not recommended for clinical use.

Long-term protective effect of surface sealants against erosive wear by intrinsic and extrinsic acids

OBJECTIVE

To test sealants to prevent erosive tooth wear caused by extrinsic and intrinsic acids under long-term exposition.

METHODS

144 bovine enamel samples were randomly allocated to twelve groups (1-12). Samples of groups 1, 5 and 9 remained unsealed (positive controls), 2, 6 and 10 were sealed with Silicon Seal Nano Mix and 3, 7 and 11 with Seal&Protect. Groups 4, 8 and 12 were sealed with flowable composite (negative controls). Groups 1-4 were immersed in artificial saliva, 5-8 in hydrochloric acid and groups 9-12 in citric acid for 28 days, respectively. After 1, 2, 4, 7, 11, 14, 21 and 28 days, solutions were renewed and enamel wear was quantified by assignation of (32)P in the solutions.

RESULTS

In all immersion solutions, lowest mineral loss was observed for the negative controls whilst highest loss was observed for unsealed positive controls. In artificial saliva and citric acid, the loss from samples sealed with Seal&Protect was not significantly different compared with negative controls whilst loss in groups sealed with Silicon Seal Nano Mix was significantly higher. In hydrochloric acid, loss from samples sealed with Seal&Protect was not different compared with that of negative controls up to 4 days. Except day 1, the mineral loss in the Seal&Protect group was significantly lower compared with that of the Silicon Seal Nano Mix group.

CONCLUSION

The tested resin based surface sealant is able to significantly reduce the erosive demineralisation of enamel caused by hydrochloric and citric acid even under long-term exposition.

Anti-erosive potential of amine fluoride, cerium chloride and laser irradiation application on dentine

METHODS

Ninety-six dentine samples were prepared from human premolars and randomly assigned to eight groups (G1-G8). Samples were treated for 30s with the following solutions: placebo (G1/G2), amine fluoride (Elmex fluid; G3/G4), cerium chloride (G5/G6) and combined fluoride/cerium chloride application (G7/G8). Samples of groups G2, G4, G6 and G8 were additionally irradiated with a carbon dioxide laser through the solutions for 30s. Acid resistance was assessed in a six-time 5-min consecutive lactic acid (pH 3.0) erosion model and calcium release was determined by atomic absorption spectroscopy (AAS). Furthermore, six additional samples per group were prepared and subjected to EDS-analysis.

RESULTS

In the non-irradiated groups, specimens of G1 (placebo) showed the highest calcium release when compared to the other treatments (G3, G5 and G7). The highest acid resistance was observed for G7. In G3, calcium release was lower than in G5, but higher than in G7. In general (except for the placebo groups), calcium release in the laser-irradiated groups was higher compared with the respective non-irradiated groups. EDS showed a replacement of calcium by cerium and of phosphor by fluoride.

CONCLUSION

The highest anti-erosive potential was found after combined cerium chloride and amine fluoride application. Laser irradiation had not adjunctive effect.

Prevention of toothbrushing abrasion of acid-softened enamel by CO(2) laser irradiation

OBJECTIVE

The aim of the present study was to evaluate the effect of CO(2) laser irradiation (10.6μm) at 0.3J/cm(2) (0.5μs; 226Hz) on the resistance of softened enamel to toothbrushing abrasion, in vitro.

METHODS

Sixty human enamel samples were obtained, polished with silicon carbide papers and randomly divided into five groups (n=12), receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C). After surface treatment they were submitted to a 25-day erosive-abrasive cycle in 100ml sprite light (90s) and brushed twice daily with an electric toothbrush. Between the demineralization periods samples were immersed in supersaturated mineral solution. At the end of the experiments enamel surface loss was determined using a contact profilometer and morphological analysis was performed using scanning electron microscopy (SEM). For SEM analysis of demineralization pattern, cross-sectional cuts of cycled samples were prepared. The data were statistically analysed by one-way ANOVA model with subsequent pairwise comparison of treatments.

RESULTS

Abrasive surface loss was significantly lower in all laser groups compared to both control and fluoride groups (p<0.0001 in all cases). Amongst the laser groups no significant difference was observed. Softened enamel layer underneath lesions was less pronounced in laser-irradiated samples.

CONCLUSION

Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5μs, 226Hz) either alone or in combination with amine fluoride gel significantly decreases toothbrushing abrasion of softened-enamel, in vitro.

Effect of a single application of TiF4 and NaF varnishes and solutions combined with Nd:YAG laser irradiation on enamel erosion in vitro

OBJECTIVE

This in vitro study aimed to analyze the influence of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and sodium fluoride (NaF) varnishes and solutions to protect enamel against erosion.

BACKGROUND DATA

The effect of Nd:YAG laser irradiation on NaF and AmF was analyzed; however, there is no available data on the interaction between Nd:YAG laser irradiation and TiF(4).

METHODS

Bovine enamel specimens were pre-treated with NaF varnish, TiF(4) varnish, NaF solution, TiF(4) solution, placebo varnish, Nd:YAG (84.9 J/cm(2)), Nd:YAG prior to or through NaF varnish, Nd:YAG prior to or through TiF(4) varnish, Nd:YAG prior to or through NaF solution, Nd:YAG prior to or through TiF(4) solution, and Nd:YAG prior to or through placebo varnish. Controls remained untreated. Ten specimens in each group were then subjected to an erosive demineralization (Sprite Zero, 4 × 90 s/day) and remineralization (artificial saliva, between the erosive cycles) cycling for 5 days. Enamel loss was measured profilometrically (μm). Additionally, treated but non-eroded specimens were additionally analyzed by scanning electron microscope (SEM) (each group n = 2). The data were statistically analyzed by ANOVA and Tukey's post-hoc test (p < 0.05).

RESULTS

Only TiF(4) varnish (1.8 ± 0.6 μm), laser prior to TiF(4) varnish (1.7 ± 0.3 μm) and laser prior to TiF(4) solution (1.4 ± 0.3 μm) significantly reduced enamel erosion compared to the control (4.1 ± 0.6 μm). SEM pictures showed that specimens treated with TiF(4) varnish presented a surface coating.

CONCLUSIONS

Nd:YAG laser irradiation was not effective against enamel erosion and it did not have any influence on the efficacy of F, except for TiF(4) solution. On the other hand, TiF(4) varnish protected against enamel erosion, without the influence of laser irradiation.

Prevention of erosive/abrasive enamel wear due to orange juice modified with dietary supplements

OBJECTIVE

The aim of this study was to evaluate the erosive/abrasive enamel wear after contact with orange juices modified with different dietary supplements.

METHODS

A total of 96 bovine enamel samples were prepared and allocated to eight groups (1-8; n = 12). Samples were eroded (120 s) in 200 ml of the following eight solutions: 1: water (control), 2: orange juice, 3: water + calcium effervescent tablet, 4: orange juice + calcium effervescent tablet, 5: water + 0.75 g acid/base regulating powder (Probase), 6: water + 0.375 g Probase, 7: orange juice + 0.75 g Probase and 8: orange juice + 0.375 g Probase. After erosion, the samples were brushed with 40 brushing strokes (load 2.5 N). Enamel wear was measured using surface profilometry after 20 and 40 cycles of erosion/abrasion respectively.

RESULTS

Highest mean enamel wear (± SD) after 20 and 40 cycles of erosion/abrasion was observed for the unmodified orange juice (group 2) (0.605 ± 0.240 μm; 1.375 ± 0.496 μm respectively). The enamel wear in all other groups (3-8) was significantly lower (P < 0.0001 respectively) with no significant difference within these groups and compared with water (control).

CONCLUSION

Erosive/abrasive enamel wear induces by orange juice and tooth brushing could be reduced significantly by modification with free available dietary supplements.

Effect of titanium tetrafluoride and amine fluoride treatment combined with carbon dioxide laser irradiation on enamel and dentin erosion

OBJECTIVE

This in vitro study aimed to analyze the influence of carbon dioxide (CO(2)) laser irradiation on the efficacy of titanium tetrafluoride (TiF(4)) and amine fluoride (AmF) in protecting enamel and dentin against erosion.

METHODS

Bovine enamel and dentin samples were pretreated with carbon dioxide (CO(2)) laser irradiation only (group I), TiF(4) only (1% F, group II), CO(2) laser irradiation before (group III) or through (group IV) TiF(4) application, AmF only (1% F, group V), or CO(2) laser irradiation before (group VI) or through (group VII) AmF application. Controls remained untreated. Ten samples of each group were then subjected to an erosive demineralization and remineralization cycling for 5 days. Enamel and dentin loss were measured profilometrically after pretreatment, 4 cycles (1 day), and 20 cycles (5 days) and statistically analyzed using analysis of variance and Scheffe's post hoc tests. Scanning electron microscopy (SEM) analysis was performed in pretreated but not cycled samples (two samples each group).

RESULTS

After 20 cycles, there was significantly less enamel loss in groups V and IV and significantly less dentin loss in group V only. All other groups were not significantly different from the controls. Lased surfaces (group I) appeared unchanged in the SEM images, although SEM images of enamel but not of dentin showed that CO(2) laser irradiation affected the formation of fluoride precipitates.

CONCLUSION

AmF decreased enamel and dentin erosion, but CO(2) laser irradiation did not improve its efficacy. TiF(4) showed only a limited capacity to prevent erosion, but CO(2) laser irradiation significantly enhanced its ability to reduce enamel erosion.

Gels containing MMP inhibitors prevent dental erosion in situ

Matrix metalloproteinase (MMP) inhibition has been shown to reduce dentin caries progression, but its role in dental erosion has not yet been assessed. This study tested the hypothesis that gels containing MMP inhibitors (epigallocatechin gallate-EGCG and chlorhexidine) can prevent dental erosion. Volunteers (n = 10) wore palatal devices containing bovine dentin blocks (n = 10/group) treated for 1 min with EGCG at 10 (EGCG10) or 400 microM (EGCG400), chlorhexidine at 0.012%, F at 1.23% (NaF), and no vehicle (placebo). Erosion was performed with Coca-Cola (5 min) 4X/day during 5 days. The wear, assessed by profilometry (mean +/- SD, microm), was significantly reduced by the gels containing MMP inhibitors (0.05 +/- 0.02(a), 0.04 +/- 0.02(a), and 0.05 +/- 0.02(a) for EGCG10, EGCG400, and chlorhexidine, respectively) when compared with NaF (0.79 +/- 0.35(b)) and placebo gels (1.77 +/- 0.35(b)) (Friedman and Dunn's tests, p < 0.01). The use of gels delivering MMP inhibitors was shown to prevent erosion and opens a new perspective for protection against dental erosion.

Influence of two different fluoride compounds and an in vitro pellicle on the amount of KOH-soluble fluoride and its retention after toothbrushing

OBJECTIVE

To determine the influence of two different fluoride compounds and an in vitro pellicle on KOH-soluble fluoride formation - its retention and resistance to toothbrushing.

MATERIAL AND METHODS

Forty bovine incisors were randomly assigned to four groups (A-D). Of five samples prepared per tooth, one remained untreated and served as a baseline control. Groups A and B were pretreated with artificial saliva and groups C and D with human saliva. Groups A and C were treated with amine fluoride and groups B and D with sodium fluoride. After treatment, samples were brushed with 25, 50, and 75 brushing strokes. The amount of KOH-soluble fluoride formed on the enamel samples was measured at baseline, after application, and after 25, 50, and 75 brushing strokes. Fluoride uptake was calculated by unpaired t-tests and fluoride retention by paired t-tests.

RESULTS

No statistically significant differences in the KOH-soluble fluoride uptake of the groups that were pretreated (A vs B and C vs D) or treated equally (A vs C and B vs D) were observed. Retention of the KOH-soluble fluoride in the brushed samples was higher when the samples were pretreated with human saliva and treated with sodium fluoride than when the samples were pretreated with artificial saliva and treated with sodium fluoride.

CONCLUSIONS

The fluoride compound and the acquired human in vitro pellicle have no influence on the uptake of KOH-soluble fluoride, but show a significant influence on abrasion resistance.

Insights into preventive measures for dental erosion

Dental erosion is defined as the loss of tooth substance by acid exposure not involving bacteria. The etiology of erosion is related to different behavioral, biological and chemical factors. Based on an overview of the current literature, this paper presents a summary of the preventive strategies relevant for patients suffering from dental erosion. Behavioral factors, such as special drinking habits, unhealthy lifestyle factors or occupational acid exposure, might modify the extent of dental erosion. Thus, preventive strategies have to include measures to reduce the frequency and duration of acid exposure as well as adequate oral hygiene measures, as it is known that eroded surfaces are more susceptible to abrasion. Biological factors, such as saliva or acquired pellicle, act protectively against erosive demineralization. Therefore, the production of saliva should be enhanced, especially in patients with hyposalivation or xerostomia. With regard to chemical factors, the modification of acidic solutions with ions, especially calcium, was shown to reduce the demineralization, but the efficacy depends on the other chemical factors, such as the type of acid. To enhance the remineralization of eroded surfaces and to prevent further progression of dental wear, high-concentrated fluoride applications are recommended. Currently, little information is available about the efficacy of other preventive strategies, such as calcium and laser application, as well as the use of matrix metalloproteinase inhibitors. Further studies considering these factors are required. In conclusion, preventive strategies for patients suffering from erosion are mainly obtained from in vitro and in situ studies and include dietary counseling, stimulation of salivary flow, optimization of fluoride regimens, modification of erosive beverages and adequate oral hygiene measures.

Impact of the in situ formed salivary pellicle on enamel and dentine erosion induced by different acids

OBJECTIVE

To investigate and compare the protective impact of the in situ formed salivary pellicle on enamel and dentine erosion caused by different acids at pH 2.6.

METHODS

Bovine enamel and dentine samples were exposed for 120 min in the oral cavity of 10 healthy volunteers. Subsequently, enamel and dentine pellicle-covered specimens were extraorally immersed in 1 ml hydrochloric, citric or phosphoric acid (pH 2.6, 60 s, each acid n=30 samples). Pellicle-free samples (each acid n=10) served as controls. Calcium release into the acid was determined by atomic absorption spectroscopy. The data were analysed by two-way ANOVA and Tukey's test (alpha=0.05).

RESULTS

Pellicle-covered samples showed significantly less calcium loss compared to pellicle-free samples in all acid groups. The mean (SD) pellicle protection (% reduction of calcium loss) was significantly better for enamel samples [60.9 (5.3)] than for dentine samples [30.5 (5.0)], but revealed no differences among the acids.

CONCLUSION

The efficacy of the in situ pellicle in reducing erosion was 2-fold better for enamel than for dentine. Protection of the pellicle was not influenced by the kind of acid when enamel and dentine erosion was performed at pH 2.6.