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Purpose: To test different kinds of mechanical and chemical pre-treatments of previously sealed dentin before re-sealing. Methods: 75 bovine dentin samples were precycled for 3 days (per day: 6x1 minute erosion (HCl; pH 2.3), and kept in artificial saliva in dwell time and overnight. Group 1 samples (n=15) remained untreated (control). Remaining samples were sealed with Seal&Protect (S&P). After thermo-mechanical loading (5,000 cycles, 50/5°C, 11,000 blushing strokes) a first measurement was performed to evaluate permeability of the sealant. Permeability was tested by storing the samples in HCl (pH 2.3; 24 hours) and measuring the calcium release into the acid by atomic absorption spectroscopy. Based on these calcium release values, the previously sealed samples were allocated to four groups (2-5) according to a stratified randomization. Samples of Groups 2-5 were re-sealed with S&P after either being treated with ethanol (Group 3), silane-coupling-agent (Group 4) or sandblasting (Group 5). After re-sealing, all samples had a second measurement of permeability. After another thermo-mechanical loading, a third evaluation of permeability was conducted. Results: At all measurements, calcium release was significantly higher in the untreated control group than in the sealed Groups 2-5 with no significant differences among the sealed groups. Within Groups 2-5, calcium release at the first and third measurement was higher compared with that at the second measurement (P< 0.05). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective. Application of SnCl2/AmF/NaF containing mouth rinse showed good protection against erosion. The aim of the study was to evaluate if this is due to the amount of KOH-soluble fluoride (KOHsF) formed or its resistance under erosive conditions. Methods. One hundred and fifty bovine enamel samples were allocated to five groups (n = 30) and were once eroded in 0.05 mol/l citric acid (5 min). Samples were stored in artificial saliva for 4 days. Samples of two groups (erosive-SnCl2 + erosive-NaF) were eroded 6 × for 5 min. The remaining samples were stored in aqua dest deionised water. Each day the samples were treated twice for 2 min with 1 ml SnCl2/AmF/NaF-solution (erosive-SnCl2;neutral-SnCl2/AmF/NaF) or NaF-solution (erosive-NaF;neutral-NaF). The fifth group remained untreated (control). On day 5, 10 samples of each group were used for determination of KOHsF (series 1). The remaining samples were again eroded (erosive-SnCl2 + erosive-NaF) or stored in artificial saliva (neutral-SnCl2 + neutral-NaF). KOHsF of another 10 samples of each group was measured (series 2). The last 10 samples of each group were also treated as described above and the amount of KOHsF was measured (series 3). Results. In each series 1-3 KOHsF in group erosive-SnCl2/AmF/NaF were significantly higher. No significant loss of KOHsF between the series 1-3 was observed (except for control). Conclusion. SnCl2/AmF/NaF containing mouth rinse revealed a better formation of KOH-soluble fluoride as the NaF-solution, although the applied fluoride compound has no influence on the stability of the KOHsF under erosive conditions, leading to the conclusion that the resistance of KOHsF is not responsible for the difference in the protection against dental erosion. [ABSTRACT FROM AUTHOR]

Objectives. This in-situ study aimed to investigate the potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) crème and fluoride mouth rinse to re-harden erosively softened enamel and to evaluate the influence of an intra-oral or extra-oral application. Methods. Ten volunteers performed five experimental series. Per series, four bovine enamel samples were extra-orally softened by immersion in Sprite light® (2 min) and subsequently worn intra-orally for 5 min in intra-oral appliances. Thereafter, samples were treated (3 min) with either 250 ppm AmF/SnF2 solution (Meridol) (series 1 and 3) or CPP-ACP crème (Tooth Mousse) (series 2 and 4). Application of the substances was performed extra-orally (series 1 and 2) or intra-orally (series 3 and 4). Untreated specimens served as control (series 5). The appliances were worn for 4 h afterwards. Knoop microhardness (KHN) measurement was performed at baseline, after softening and after completing of the respective run. Data were statistically analyzed by ANOVA and Bonferroni/Dunn post-hoc test. Results. No significant difference in baseline microhardness was observed, while immersion in Sprite light reduced the microhardness significantly. Significant re-hardening after intra-oral exposure occurred in all series, but baseline microhardness was not achieved. Microhardness in series 2 was significantly higher than that in series 1 and 5. No significant differences in KHN were detected between series 3, 4 and 5. The re-hardening ΔKHN (final microhardness - microhardness after erosion) was not significant different in all five series. Conclusion. Intra-oral application of CPP-ACP crème or fluoride solution provides no benefit regarding re-hardening of erosively softened enamel. [ABSTRACT FROM AUTHOR]

Objective: To determine how differences in abrasiveness (RDA) influence cleaning capabilities of toothpastes., Methods: For this in vitro trial, 60 bovine dentin samples were prepared and divided into six groups (G1-G6; n = 10). Groups G1-G5 were arranged in order from low to high toothpaste abrasiveness (G1: RDA: 12, G2: RDA: 29, G3: RDA: 43, G4: RDA: 71, and G5: RDA: 143). Samples in group G6 were used as a negative control and later brushed with pure artificial saliva. In preparation for testing, the dentin samples were stained with a black tea mixture. The respective toothpastes were mixed with artificial saliva in a 1:2 ratio to produce a toothpaste slurry. The samples were brushed for a total of 25 min (with measurement intervals at 2-, 5-, 10-, and 25-min) using a manual toothbrush in an automated brushing machine. The cleaning efficacy of the toothpastes was determined using photographs connected to a planimeter computer program and statistically evaluated., Results: Analysis of the median cleaning efficacy values showed that the toothpastes with a higher abrasiveness achieved a greater cleaning effect at each time point. All toothpastes showed a statistically significant difference (p < 0.05) in their cleaning efficacy (taking into account the median, interquartile range (IQR), minimum and maximum values) after 25 min of brushing., Conclusions: With increasing RDA value, the cleaning efficiency of the toothpastes tested rises. However, a doubling of the RDA value does not necessarily elicit a twofold increase in cleaning effect., (© 2024 The Author(s). International Journal of Dental Hygiene published by John Wiley & Sons Ltd.)

Purpose: This in-vitro study aimed to investigate the cleaning efficacy of 18 different manual children's toothbrushes applying horizontal, vertical, and rotational movements, as well as to evaluate the rounding of their filament ends., Materials and Methods: Models equipped with artificial teeth (coated with titanium dioxide) were brushed using a brushing machine with clamped manual children's toothbrushes. The machine carried out horizontal, vertical, and rotational movements for 1 min with a constant contact pressure of 100 g. The percentage of the area of titanium dioxide removed from the buccal, mesial, distal and total surfaces of the artificial teeth corresponded to the cleaning efficacy. To assess the filament design, a scanning electron microscope was used to check the morphology of the filaments which was scored with Silverstone and Featherstone scale. SPSS 22 was used for data analysis., Results: The rotational and the vertical movements achieved the best cleaning efficacy with all tested toothbrushes. The vast majority of the tested toothbrushes had their poorest cleaning efficacy in the horizontal movement. Only a small part of the children's toothbrushes (3 out of 18) had a correct and acceptable proportion of rounded bristle ends., Conclusions: Based on the present results, it could be concluded that the cleaning efficacy of different manual children's toothbrushes varied considerably. The best cleaning efficacy was almost always observed for rotational and vertical movements.

Purpose: This in-vitro study deals with the question of whether the wear and tear of the manual toothbrush over a simulated timeframe up to 24 months has an effect on its cleaning performance. The purpose was to find indications as to whether and when a toothbrush needs to be replaced based on its cleaning performance., Materials and Methods: Models equipped with artificial teeth (coated with titanium dioxide) were brushed in-vitro using a brushing machine with clamped manual toothbrushes. The machine carried out even, horizontal brush strokes (120 brush strokes/min) for 1 min with a constant contact pressure of 2.5 N. The percentage of the area of titanium dioxide removed from the buccal, mesial and distal surfaces of the artificial teeth corresponded to the cleaning performance. The manual toothbrushes were used on bovine roots to simulate the wear and tear after 2, 4, 6, 12, 18, 24 months of use. The cleaning performance was re-evaluated after each simulated timepoint of wear. In addition, the brushes were photographed after each cycle., Results: An increase in the in-vitro cleaning performance of the toothbrush was observed up to 6 months of wear compared to the starting point. After that, the cleaning performance decreased somewhat, but always remained above the initial cleaning performance., Conclusion: Based on the in-vitro cleaning performance after 24 months, the toothbrush would not have to be replaced. However, this in-vitro study cannot determine when a toothbrush should be replaced, because in-vivo it is also dependent on a variety of other factors such as fraying and microbial colonisation. Direct transfer of results from this study to everyday clinical practice is therefore difficult.

Purpose: To determine the salivary flow rate and subsequent dilution of toothpaste and assess the pH of oral fluids during toothbrushing with toothpastes of various pHs., Materials and Methods: The study was conducted as an in-vivo trial involving 30 healthy volunteers. The participants took part in a series of trials distributed over four appointments. After a screening check, in which the participants' stimulated and unstimulated salivary flow rate and buffering capacities were determined, four test series involving toothbrushing were conducted. Participants brushed their teeth using a manual toothbrush for 2 min: once without toothpaste and three times using toothpastes of varying pHs. The salivary flow rate and subsequent dilution of the toothpaste was determined. Additionally, the pH of the collected oral fluid was analysed., Results: Brushing teeth with toothpaste caused a statistically significant increase in salivary flow rate (median/IQR in ml/min) (Elmex Kariesschutz 3.29/1.36, Colgate Total Original 3.23/1.08, Elmex Sensitive Professional 3.18/1.39) when compared to brushing teeth using a manual toothbrush without toothpaste (1.85/0.78) (p < 0.05). The variation in pH of the oral fluid samples was dictated primarily by the pH of the toothpaste used., Conclusion: The salivary flow rate when brushing using toothpaste was similar across all tested toothpastes, independent of pH, and had an average median of 3.23 ml/min. The dilution of 1 g of toothpaste during a standard toothbrushing procedure of 2 min is therefore approximately at a ratio of one part toothpaste to 6.5 parts saliva.

Purpose: This in-situ-study investigated if rinsing the oral cavity with a calcium containing solution or a fluoride containing mouthwash immediately before an erosive attack leads to reduced enamel softening., Materials and Methods: Bovine enamel samples (n = 240) with measured baseline surface microhardness (KHN) were assigned to five series (S1-5). Twelve participants carried out each series as follows: Four enamel samples of the associated test series were placed in an intraoral appliance and carried in each participants' mouth. After 30 min, the participants either rinsed the oral cavity for 60 s with 30 ml of a solution prepared from a 1,000 mg calcium effervescent tablet dissolved in 100 ml water (S2), an 800 mg calcium containing mineral supplement powder (5 g) dissolved in 200 ml water (S3), a fluoride (500 ppm) mouthwash (S4), a fluoride (500 ppm) and stannous chloride (800 ppm) containing mouthwash (S5), or did not rinse with any test solution before the erosive attack (S1, negative control). The participants subsequently rinsed the oral cavity with 100 ml of a soft drink (Sprite Zero) for 60 s to simulate the erosive attack and immediately afterwards with water to stop the erosive process. As final step, surface microhardness was measured a second time and hardness loss (∆KHN) calculated. Differences of ∆KHN between the series were investigated by fitting a mixed effect model to the data set., Results: The highest loss of microhardness and thus softening of enamel (mean of ∆KHN; lower/upper confidence level) was observed in the negative control (S1: 60.2; 67.6/52.8). While no statistically significant difference (P > 0.05) compared to S1 could be found in S2 (50.0; 57.4/42.5) and S3 (54.6; 62.1/47.2), statistically significantly less softening of enamel (P < 0.001) was discovered in S5 (33.8; 41.2/26.4) and S4 (41.8.2; 49.3/34.4). S5 showed the overall lowest values for ∆KHN and thus best protection from enamel softening., Conclusion: Rinsing with a fluoride mouthwash or a fluoride and stannous chloride containing mouthwash immediately before an erosive attack reduces the softening of enamel. None of the investigated calcium-containing solutions was able to reduce erosion induced softening of enamel.

The aim of this study was to examine the wear of three different composite materials usable for vertical bite reconstruction under erosive/abrasive conditions and to compare them with the bovine dental hard tissues enamel and dentin in-vitro. The composite materials Filtek Supreme XTE, CeraSmart and Brilliant Crios and bovine enamel and dentin specimens were evenly allocated to five groups (n=10). Samples were firstly exposed to hydrochloric acid for 1 min, then stored for 30 min in artificial saliva. In the second step, the samples were brushed for 1 min with 100 brushing strokes each and an applied force of 2.5 N in an automated brushing device. After 60 of these erosive/abrasive cycles, wear of the samples was determined by contact profilometry. Filtek Supreme XTE showed significantly less wear (mean ± standard deviation; 0.15 ± 0.11 μm) compared to the other two composite materials (p < 0.05). No significant difference (p > 0.05) could be found between CeraSmart (0.25 ± 0.03 μm) and Brilliant Crios (0.24 ± 0.04 μm). The two bovine dental hard tissues, enamel (13.70 ± 0.94 μm) and dentin (50.08 ± 4.46 μm), each showed a significantly higher amount of wear than the three restorative materials (p <0.05). In conclusion, this study exhibited that the three composite materials, Filtek Supreme XTE, CeraSmart and Brilliant Crios, were more resistant under erosive/abrasive conditions compared to bovine enamel and bovine dentin, respectively.

Purpose: To investigate the possibility of reducing the erosive potential of salad dressings by adding yoghurt., Materials and Methods: Two hundred enamel samples from bovine teeth were allocated to 20 groups (n = 10). Three modified commercially available balsamic dressings (addition of 10%, 20%, 50% yoghurt or 8.8 mM calcium chloride) and two homemade salad dressings with and without modifications were tested. Enamel samples were eroded for 2 min, rinsed for 30 s with tap water and finally abraded (20 brushing strokes with toothpaste slurry). After 40 of these cycles of erosion/abrasion, the dental hard tissue loss was determined by contact profilometry., Results: For commercially available salad dressings, modification yielded a statistically significant decrease in enamel wear. The exception was Anna's Best Dressing Balsamico modified with 8.8 mM calcium chloride, for which no reduction was found compared with the unmodified dressing. For all homemade dressings, a significant reduction was observed when modified with 20% yoghurt. However, when only 10% yoghurt was added to the homemade dressings, an increase of the erosive potential was observed compared to the unmodified dressing., Conclusions: The study shows that increasing the calcium concentration only with calcium chloride in commercially available salad dressings did not show predictable outcomes to reduce erosion. However, mixing 20% plain yoghurt into the dressings reduced the erosive potential statistically significantly.

Purpose: To determine the impact of the brushing protocol on dentin wear by comparing continuous to intermittent brushing, with the same total time of brushing., Materials and Methods: Dentin specimens (n = 120) were evently distributed into six groups (A-F). The samples were brushed with slurries of different relative dentin abrasivity (RDA): Groups A+B (Sident 2480-1; RDA 85), groups C+D (Zeodent 113; RDA 67), and groups E+F (Zeodent 103; RDA 174). Groups A+C+E were brushed continuously (25 min) with one slurry preparation, while groups B+D+F were brushed intermittently (25 x 1 min) with a renewal of the slurry after each sequence. Dentin wear was determined using surface profilometry and statistically analysed with ANOVA and post-hoc tests., Results: Neither the mode of brushing (p = 0.72) nor the interaction (p = 0.18) of the brushing mode with the type of abrasive particles had a significant influence on the abrasive dentin wear. Only the type of abrasive particles had a statistically significant influence on abrasive dentin wear (p < 0.001)., Conclusion: The mode of brushing (continuously or intermittently) has no influence on abrasive dentin wear.

Aim of this study was to get an overview of what dentists estimate to be the reason for failure of adhesive composite restorations and to gain knowledge about potential future foci for targeted further education. Therefore, a survey about the fabrication of composite restorations was conducted in the course of seven dental conferences with the main topic tooth-prevention. A total of 577 dentists participated in the survey. The most often called estimated factor for failure of composite restorations was the "dentist" (70.7%), followed by "indication" (32.2%), "material" (8.5%) and "patient" (8.1%). Participants estimated insufficient drying and fluid management (67.9%), incorrect application of the adhesive system (41.8%), insufficient lightpolymerisation (31.2%) and errors in incremental technique (27.6%) to be the main mistakes. The participating dentists claimed to attach great importance to careful drying and fluid management (60.8%), thorough adhesive application (37.3%), adequate incremental technique (32.6%) and sufficient lightpolymerisation (28.8%) while placing their own restorations. According to the survey participants, the treating dentist has the greatest influence on the quality and longevity of composite restorations. Drying and fluid management was the most often called estimated reason for failure but at the same time the step which is given the greatest caution.

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/mm 2 ] (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., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020. Published by Elsevier Ltd.)

Purpose: To investigate dental enamel wear caused by erosion and abrasion while using a combination of anti-erosive toothbrush/-paste., Materials and Methods: A total of 60 enamel specimens from bovine incisors were randomly assigned into five groups of 12 specimens each (G1-5, n = 12): (G1) control group (no treatment), (G2) standard medium toothbrush Paro M43 and standard toothpaste Elmex Caries Protection, (G3) standard medium toothbrush Paro M43 and anti-erosive toothpaste Elmex Protection Erosion, (G4) anti-erosive toothbrush Elmex Erosion Soft and standard toothpaste Elmex Caries Protection, (G5) anti-erosive toothbrush Elmex Erosion Soft and anti-erosive toothpaste Elmex Protection Erosion. Initially, surface baseline profiles were recorded using profilometry. In a total of 60 cycles, all specimens were exposed to hydrochloric acid (pH = 3) for 1 min, rinsed with tap water to stop the erosive attack and brushed according to the specific protocol of each group (15 brushing strokes per run). Enamel loss was determined by comparing the surface profiles before and after 60 cycles and the results were statistically analysed using analysis of variance (ANOVA)., Results: The significantly highest loss of enamel was observed in the control group G1(1.4 ± 0.20 µm) (p < 0.001). G2 turned out to be the most abrasive toothbrush/-paste combination (1.12 ± 0.15 µm), G3 the least invasive (0.40 ± 0.04 µm) (p < 0.001, respectively)., Conclusion: All combinations of the investigated toothbrushes/-pastes reduce erosive/abrasive enamel wear. However, the highest reduction was observed for the combination of anti-erosive toothpaste and standard toothbrush (G3).

Objectives: This in vitro study aimed to evaluate and compare the effect of two different bioactive glasses, a hydroxyapatite-containing, fluoride-free toothpaste (HTP) and a fluoride toothpaste (FTP) on the remineralization behavior of initial caries lesions., Materials and Methods: A total of 100 bovine enamel samples were randomly allocated to five groups of 20 samples each: NC = negative control group (artificial saliva); HTP = HTP group (Karex); FTP = FTP group (Elmex caries protection, 1,400 ppm); FTP + BGnano = FTP followed by Actimins bioactive glass; FTP + BGamorph = FTP followed by Schott bioactive glass. Radiographic documentation (advanced transversal microradiography; aTMR) was applied before and after all samples were exposed to a demineralizing gel for 10 days. Over a period of 28 days, samples were covered twice a day (every 12 h) with a toothpaste slurry of the respective test group or with artificial saliva in NC for 60 s and brushed with 15 brushing strokes. Samples in FTP + BGnano and FTP + BGamorph were additionally treated with the respective bioactive glass slurry for 30 s after brushing with the FTP. In the meantime, all samples were stored in artificial saliva. After 28 days, the structure of all samples was assessed again using aTMR and compared to the values measured after demineralization. The statistical evaluation of the integrated mineral loss was performed using Kruskal-Wallis test followed by a post hoc Conover test., Results: The FTP revealed the significantly highest increase of mineral content while the HTP showed the significantly lowest remineralization. Compared to artificial saliva, the use of the HTP or the combined application of FTP followed by bioactive glasses (FTP + BGnano and FTP + BGamorph) showed no significant remineralization., Conclusion: Under remineralizing in vitro conditions, brushing with 1,400 ppm FTP induced significantly more remineralization compared to storage in artificial saliva. The additional administration of both bioactive glasses as well as the substitutional brushing with an HTP resulted in significantly less remineralization compared to brushing with 1,400 ppm FTP., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

This review assessed defined specific areas of diagnostic, prophylactic and therapeutic procedures in the field of preventive and restorative dentistry and determined the prevalence and risk of bacteremia, given the assumption that any direct or indirect manipulation of perfused dental and periodontal tissues may lead to bacterial access to the systemic circulatory vascular system. We found that all of the evaluated interventions presented at least some risk of bacteremia. With increasing “degree of invasiveness”, the probability of a possible bacteremia increased. A targeted and synoptic case planning remains therefore mandatory, especially in cases with increased risk, for instance for endocarditis.

Objectives: The study evaluated the suitability of pure crystalline hydroxyapatite (HA) as a substitute for human (H) and bovine (B) enamel in erosion experiments., Methods: Human and bovine enamel and hydroxyapatite specimens (n = 18 each) were submitted to demineralisation by HCl at pH values of 3.0, 2.6 and 2.0 (1.0, 2.5, and 10 mmol/l concentration). Specimens were eroded in a superfusion chamber for 7 min (flow rate: 1 μl/s). Multiple fluid samples were taken per specimen throughout the exposure period. The dissolved calcium content was measured using a colorimetric assay with Arsenazo III reagent, to serve as surrogate for erosive substance loss. Additionally, erosive tissue loss was quantified by profilometry. Differences in erosive substance loss were assessed by the Kruskal-Wallis and Conover's posthoc test., Results: Good agreement in erosive substance loss between HA and human specimens was found at pH 2.6, as no statistically significant difference and considerable overlap of their respective interquartile ranges was observed. At pH 2.0 and 3.0, a statistically significant difference between HA and human and bovine enamel was determined. HA consistently tended to have lower mean dissolution rates, with a maximum deviation from human enamel of -16% at pH 3. It displayed lower specimen variability with an average coefficient of variation of 17%, compared to 25% (H) and 25% (B), respectively., Conclusions: Crystalline hydroxyapatite may not be suitable for full substitution of biologic enamel in erosion experiments focusing on absolute measurement values, but is useful for establishing consistent relative trends between erosive agents due to biosimilar erosion behavior and lower experimental variability. This is especially true for preliminary studies where approval for use of biological samples is restricted., Clinical Significance: Crystalline hydroxyapatite is a useful substitute of human or bovine enamel in experiments studying chemical aspects of dental erosion., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Tooth Erosions Associated with Gastroesophageal Reflux: Cause, Prevention and Restorative Therapy Abstract. Dental erosions are caused by the recurring contact of solutions which are unsaturated in tooth minerals,ith hard tooth substances. This initially leads to softening and later to an irreversible loss of hard tooth substance. Erosion is observed particularly with excessive consumption of acidic foods (e.g. soft drinks or citrus fruits) but also in connection with gastrointestinal (gastroesophageal reflux disease) or psychosomatic diseases (anorexia nervosa or bulimia nervosa). The aim of this article is to define dental erosions, their causes, prevalence and consequences as well as possible preventive measures. Based on a clinical example of a patient with reflux-related erosions, a therapy option with direct composite tooth build-up is presented.

We compared the prevention of erosive and erosive/abrasive enamel loss by a medical minerals gel system (R.O.C.S.) to that by an anti-erosive toothpaste. Seventy-two bovine enamel samples were randomly allocated to six groups (E1–E3 and EA1–EA3; n=12). Per day, samples were eroded (2 min) 9 times using HCl (pH 2.6). Between erosive challenges and over night samples were stored in artificial saliva. Per day, samples were stored (100 s; groups E1–E3) or additionally brushed (20 brushing strokes; groups EA1–EA3) in/with slurries prepared from artificial saliva plus: no additional toothpaste (control groups E1 and EA1), elmex erosion protection toothpaste (groups E2 and EA2), or R.O.C.S. toothpaste (groups E3 and EA3). Once per day, samples of groups E3 and EA3 were additionally treated (40 min) with a slurry prepared from artificial saliva and R.O.C.S. medical minerals gel. After 7, 14 and 21 days enamel loss was measured by surface profilometry and analyzed by Kruskal-Wallis tests and Conover post-hoc tests. Under erosive conditions only (groups E1–E3), at each time point of measurement the significantly lowest enamel loss was observed in group E2. Substance loss in group E3 was significantly higher, but significantly lower compared to that of group E1. Under erosive/abrasive conditions (groups EA1–EA3), at each time point of measurement the significantly lowest enamel wear was observed in group EA2. Wear in group EA3 was significantly higher even compared to that of group EA1. The tested R.O.C.S. medical minerals gel system was able to reduce erosive enamel loss but not erosive/abrasive enamel wear, and it was less effective than the elmex erosion protection toothpaste.

It was the aim of the current in vitro study to test the erosion-preventive potential of an experimental surface sealant (K-0184) and currently marketed self-etch adhesive systems under abrasive conditions. Ninety-six dentine specimens were randomly allocated to eight groups (n=12): (1) positive control (no treatment), (2) K-0184, (3) Shield Force Plus, (4) Xeno Select, (5) Scotchbond Universal, (6) Adhese Universal, (7) OptiBond All-In-One, and (8) Clearfil SE Bond. Before and after sealing, dentine specimens were measured profilometrically to determine the layer thickness of the protective agents.During 12 days, the specimens were demineralized daily for 5 min using hydrochloric acid (pH=3) and abraded by applying 600 brushing strokes (F=2.5 N). Calcium content in the hydrochloric acid was determined using atomic absorption spectroscopy. Calcium concentration was consistently highest in the positive control group (p < 0.05 compared to all other groups). The lowest cumulated Ca release was measured for K-0184; it differed significantly (p < 0.05) from that determined in groups 4, 6, and 7. K-0184 also had the highest layer thickness (p < 0.05 compared to all other groups). It was concluded that the experimental surface sealant K-0184 and the adhesive systems Xeno Select, Scotchbond Universal, Adhese Universal, and Clearfil SE Bond prevent dentine erosion under the current abrasive conditions with a total of 7,200 brush strokes.

Eroded enamel is more susceptible to abrasive wear than sound enamel. New toothpastes utilizing diamond particles as abrasives have been developed. The present study investigated the abrasive wear of eroded enamel by three commercially available toothpastes (one containing diamond particles) and compared it to the respective wear of sound enamel caused by these toothpastes. Seventy-two bovine enamel samples were randomly allocated to six groups (S1–S3 and E1–E3; n=12). Samples were submitted to an abrasive (S1–S3) or erosion plus abrasion (E1–E3) cycling. Per cycle, all samples were brushed (abrasion; 20 brushing stokes) with the following toothpastes: S1/E1: Signal WHITE SYSTEM, S2/E2: elmex KARIESSCHUTZ and S3-E3: Candida WHITE DIAMOND (diamond particles). Groups E1–E3 were additionally eroded with HCl (pH 3.0) for 2 min before each brushing procedure. After 30, 60 and 90 cycles enamel wear was measured by surface profilometry. Within the same toothpaste and same number of cycles, enamel wear due to erosion plus abrasion was significantly higher than due to mere abrasion. After 30, 60 and 90 cycles, no significant difference in the wear in groups S1 and S2 was observed while the wear in group E1 was significantly (p<0.05, ANOVA, Scheffecyc) lower than that in group E2. After 90 cycles, wear in group S3 was about 5 times higher than that in group S2, while wear in group E3 was about 1.3 times higher than that in group E2. As compared to the other two investigated toothpastes, the dentifrice containing diamond particles caused slightly higher abrasive wear of eroded enamel and distinctly higher wear of sound enamel compared to the conventional toothpastes under investigation.

Purpose: To evaluate the influence of different pretreatments on the microtensile bond strength (µTBS) of an etch-and-rinse adhesive to eroded dentin., Materials and Methods: Thirty-six human teeth were ground down to their dentin layer and randomly divided into six groups (G1-G6; n = 6), G1 being the control group. Only in the test groups (G2-G6) were samples subjected to erosion using citric acid (pH 2.6) 10 x 2 min per day for five days. Between the erosive attacks, samples were stored in artificial saliva. After pretreatment - none (G1); none (G2); 2% chlorhexidine (30 s) (G3); prolonged primer application (1 min) (G4); roughening with a diamond bur (G5) and 10.5% NaOCl (1 min) (G6) - the adhesive OptiBond FL was applied. After the application of composite, samples were stored in water (7 d) and µTBS was determined. Data were evaluated using one-way ANOVA and Dunnett-T post-hoc test (p < 0.05)., Results: Eroded dentin without pretreatment (G2) resulted in significant reduction of µTBS compared with uneroded dentin (G1). µTBS after pretreatment with a diamond bur (G5) or NaOCl (G6) was not significantly different from that of the uneroded control group (G1). µTBS after pretreatment with chlorhexidine (G3) or with prolonged primer application (G4) was significantly lower than in the uneroded control group (G1), and not significantly different from the eroded control group (G2)., Conclusion: The present data suggests that µTBS to eroded dentin pretreated with bur abrasion or NaOCl is similar to the µTBS to sound, uneroded dentin.

The condition of dental erosion is defined as acid-related loss of tooth structure which does not involve microorganisms. Depending on the origin of the acid, extrinsic (usually caused by acids in food) and intrinsic (caused by endogenous acid) erosion can be distinguished. The presence and severity of erosive defects depend on various parameters such as nutrition, saliva, general diseases, and mechanical stress by abrasion and attrition. As an example, dietary habits which involve frequent intake of acidic food and beverages, occupational acid exposure, as well as certain drugs or diseases that affect saliva flow rate are accompanied by an increased risk of erosive dental hard tissue defects. By a thorough clinical examination and an accurate anamnesis, various erosion-related risk factors can be identified and strategies to reduce or eliminate these factors be identified.

Objectives: This study investigated the influence of proximal box elevation (PBE) with composite resin when applied to deep proximal defects in root-filled molars with mesio-occluso-distal (MOD) cavities, which were subsequently restored with computer-aided designed/computer-aided manufacturing (CAD/CAM) ceramic or composite restorations., Materials and Method: Root canal treatment was performed on 48 human mandibular molars. Standardized MOD cavities were prepared with the distal box located 2 mm below the cemento-enamel junction (CEJ). The teeth were randomly assigned to one of four experimental groups (n = 12). In groups G1 and G2, the distal proximal box was elevated up to the level of the CEJ with composite resin (PBE). No elevation was performed in the remaining two groups (G3, G4). CAD/CAM restorations were fabricated with feldspathic ceramic (Vita Mark II, CER) in groups G1 (PBE-CER) and G3 (CER) or with resin nano-ceramic blocks (Lava Ultimate, LAV) in groups G2 (PBE-LAV) and G4 (LAV). Replicas were taken before and after thermomechanical loading (TML; 1.2 Mio cycles; 49 N; 3,000 thermocycles between 50 °C and 5 °C). Following TML, load was applied until failure. Fracture analysis was performed under a stereomicroscope (×16). Marginal quality before and after TML (tooth restoration, composite restoration) was evaluated using scanning electron microscopy (×200)., Results: After TML, lower percentages of continuous margins were observed in groups G1-G3 compared with pre-TML assessments; however, the differences were not statistically significant. For group G4-LAV, the marginal quality after TML was significantly better than in any other group. The highest mean fracture value was recorded for group G4. No significant difference was found for this value between the groups with PBE compared with the groups without PBE, regardless of the material used. The specimens restored with ceramic onlays exhibited fractures that were mainly restricted to the restoration while, in teeth restored with composite onlays, the percentage of catastrophic failures (fractures beyond bone level) was increased., Conclusion: PBE had no impact on either the marginal integrity or the fracture behavior of root canal-treated mandibular molars restored with feldspathic ceramic onlays. CAD/CAM-fabricated composite onlays were more favorable than ceramic onlays in terms of both marginal quality and fracture resistance, particularly in specimens without PBE., Clinical Relevance: Composite onlays with or without PBE may be a viable approach for the restoration of root-filled molars with subgingival MOD cavities.

Purpose: To determine the influence of the relative enamel abrasivity (REA) of fluoridated toothpaste on the uptake of KOH-soluble and structurally bound fluoride into enamel., Materials and Methods: Bovine enamel samples were randomly allocated to 6 groups (n=36 per group). Groups A to C were treated with sodium fluoride (NaF) toothpastes and groups D to F with amine fluoride (AmF) toothpastes (1500 ppm F each). The REA in groups A and D was 2, in groups B and E it was 6 and in groups C and F it was 9. Twice a day, 18 samples of each group were immersed for 2 min in a slurry (toothpaste:artificial saliva=1:3), while the remaining samples were brushed with the respective slurry (2.5 N force; 60 strokes/min; 2 min). All samples were stored at 37°C and 100% humidity. After five days, the amount of KOH-soluble and structurally bound fluoride was determined and statistically compared by Scheffe's post-hoc tests., Results: REA value and mode of application (immersion or brushing) had no significant influence on the amount of either kind of fluoride from NaF toothpastes. Only for the NaF toothpaste with REA 6 was the amount of KOH-soluble fluoride significantly higher after brushing. With AmF toothpastes, KOH-soluble and structurally bound fluoride concentrations were significantly higher when the samples were brushed. Furthermore, in the REA-2 group, the amounts of KOH-soluble fluoride (brushed or immersed) and structurally bound fluoride (brushed) were significantly higher than in the other groups., Conclusion: The REA dependency of KOH-soluble and structurally bound fluoride was found only for the AmF toothpastes. Using AmF toothpaste, the mode of application influenced the uptake of KOH-soluble and structurally bound fluoride into enamel.

Objectives: To give an overview of the impact of erosive conditions on the behavior of tooth-colored restoratives and performance of dental adhesives., Methods: Acid-induced erosive lesions of enamel and dentin often need restorative procedures for rehabilitation. Nowadays, mostly tooth-colored restoratives (ceramics or resin composites), which are adhesively fixed to the dental substrate are used for this purpose. In some cases it might be necessary to seal the exposed dentin before achieving this goal in order to combat hypersensitivities and to protect those teeth from further erosive and abrasive loss. Moreover, it is conceivable that patients will fall back into their old "erosive behavior" after the application of restoratives. The following overview describes in how far intra-oral erosive conditions might affect the integrity of restorative materials, such as composite resins and ceramics, or of dentin sealants. Additionally, the use of erosively altered enamel and dentin as substrate for adhesive technologies is elucidated., Results: In the literature, information of the behavior of tooth-colored restoratives under still persisting erosive conditions are limited and mostly based on in vitro-studies. There is information that the adhesion of dental adhesives to eroded dentin is compromised as compared to regular dentin. The impact of erosive conditions relevant for the oral cavity on ceramics and resin composites seems to be rather low, although only few clinical studies are available., Significance: The review showed that erosive conditions might have only little impact on behavior of tooth-colored restorative materials, such as composites and ceramics. Dentin sealants also seem to be rather resistant against erosive conditions and might therefore serve as an intermediary treatment option for exposed dentin surfaces. The adhesion of dentin adhesives to eroded dentin might be increased by mechanical pre-treatment of the substrate, but needs further investigation., (Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Background: The authors conducted an in vitro study to investigate the influence of several internal bleaching regimens on the composite-to-composite shear bond strength of a dental core buildup material., Methods: The authors fabricated 72 specimens from a resin-based composite core buildup and assigned them randomly to six groups (four experimental and two control groups) (n = 12 per group), according to the following bleaching agents: sodium perborate mixed with distilled water (SP/W); sodium perborate mixed with 3 percent hydrogen peroxide (SP/HP-3); sodium perborate mixed with 30 percent hydrogen peroxide (SP/HP-30); 35 percent hydrogen peroxide (HP-35). After the 12-day bleaching procedures, the authors applied a calcium hydroxide dressing for two weeks. The two control groups consisted of unbleached specimens that either did not receive (C1) or did receive (C2) the calcium hydroxide dressing. The authors cleaned and silanized the resin-based composite specimens and coated them with an intermediate adhesive resin before applying fresh composite material. They measured composite surface roughness and shear bond strength and performed statistical analyses of the data., Results: Unbleached specimens in groups C1 and C2 exhibited significantly lower composite-to-composite bond strength and significantly lower surface roughness than did specimens in groups SP/W and SP/HP-3. Bond strength in group HP-35 was significantly lower than that in group SP/W., Conclusion: Internal bleaching regimens that involve the use of sodium perborate mixed with water or 3 percent hydrogen peroxide might increase the composite-to-composite interfacial bond strength., Clinical Implications: None of the internal bleaching regimens in this study had an adverse effect on the composite-to-composite interfacial bond strength.

Objective: This study investigated effects of cerium-chloride on fibroblast and osteoblast differentiation and proliferation., Methods: MC3T3-E1 cells were plated for an alkaline phosphatase (ALP) activity test. On day 3, CeCl(3)-solutions (1, 5 or 10, w/v%) were added. After 10s, the solutions were aspirated and washed to remove residual CeCl(3). On day 6 ALP activity was determined. Cell activity and proliferation was assessed by thiazolyl blue tetrazolium dye reduction assay (MTT-test) also 3 days after exposure to the CeCl(3)-solutions. Calcium deposition by preosteoblastic cells was determined 4 weeks after the exposure of the cells by alizarin red staining. Furthermore, in all experiments the influence of adding rhBMP-2 was tested. Statistical analysis was performed by repeated-measures ANOVA using the post hoc Fisher least significant difference (LSD) test. Statistical significance was set at p < 0.05., Results: Exposure to a Ce-solution of 1% or higher reduced ALP activity significantly. The addition of rhBMP-2 was able to elevate ALP activity above control level. MTT-test showed a significant decrease in cellular activity by 5% Ce or higher. The addition of rhBMP-2 had no positive effect. For human foreskin fibroblasts, exposure to even 10% Ce yielded a significant increase in cellular activity. Ce reduced calcium deposition to a level of below 50% of the control. The addition of rhBMP-2 restored mineral deposition to control levels for all Ce concentrations., Conclusion: CeCl(3) had a stimulating effect on fibroblasts but a depressing influence on osteoblasts. However, adding rhBMP-2 could compensate the latter influence., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Introduction: Pulpal diagnostics might be improved by using molecular markers found in dentinal fluid. In the current pilot study, we tested whether matrix metallopeptidase 9 (MMP-9) levels in dentinal fluid were detectable and differed between pulps from symptomatic teeth diagnosed with irreversible pulpitis and healthy counterparts., Methods: Thirty-one patients participated; 19 were diagnosed with irreversible pulpitis, and 12 were in need of replacement of a filling close to the pulp space in a clinically healthy tooth. Dentinal fluid was collected during a period of 2 minutes from dentin cavities by using folded polyvinylidene difluoride (PVDF) membranes, which were then transferred to microcentrifugation tubes containing physiologic saline solution. Total MMP-9 levels in these solutions were assessed by using a human MMP-9 fluorescent assay, detection limit 0.25 ng/mL. MMP-9 levels between groups were compared by using Mann-Whitney U test (alpha <0.05)., Results: Three specimens from the symptomatic teeth were not included because coronal pulps proved to be necrotic on access. Dentinal fluid samples from symptomatic teeth had significantly higher MMP-9 levels than those from clinically healthy counterparts (P < .05). However, merely 7 of the 16 pulpitis samples contained detectable levels of MMP-9. None of the clinically healthy control specimens contained any detectable amounts of MMP-9., Conclusions: With a sensitive assay, it was possible to detect an enzyme linked with pulp tissue destruction (MMP-9) in dentinal fluid. However, the collection method needs to be improved to provide predictable fluid yields. Longitudinal studies should be performed to assess the predictive value of molecular markers in dentinal fluid on pulpal pathosis., (Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the effect of cerium chloride, cerium chloride/fluoride and fluoride application on calcium release during erosion of treated dentine., Methods: Forty dentine samples were prepared from human premolars and randomly assigned to four groups (1-4). Samples were treated twice a day for 5 days, 30s each, with the following solutions: group 1 placebo, group 2 fluoride (Elmex fluid), group 3 cerium chloride and group 4 combined fluoride and cerium chloride. For the determination of acid resistance, the samples were consecutively eroded six times for 5 min with lactic acid (pH 3.0) and the calcium release in the acid was determined. Furthermore, six additional samples per group were prepared and used for EDS analysis. SEM pictures of these samples of each group were also captured., Results: Samples of group 1 presented the highest calcium release when compared with the samples of groups 2-4. The highest acid resistance was observed for group 2. Calcium release in group 3 was similar to that of group 4 for the first two erosive attacks, after which calcium release in group 4 was lower than that of group 3. Generally, the SEM pictures showed a surface coating for groups 2-4. No deposits were observed in group 1., Conclusion: Although fluoride showed the best protective effect, cerium chloride was also able to reduce the acid susceptibility of dentine significantly, which merits further investigation., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The study aimed to compare the wear behaviour of human and bovine dentine due to toothbrushing with different relative dentin abrasivity (RDA) toothpastes. Forty human and 40 bovine dentine samples were prepared from bovine lower incisors or human premolars roots, and baseline surface profiles were recorded. The samples were distributed to four groups (each group n = 10 human and 10 bovine samples) and brushed with fluoridated experimental toothpastes with different RDAs (group A: RDA 10, B: RDA 20, C: RDA 50, and D: RDA 100). Toothbrushing was performed in an automatic brushing machine with a brushing frequency of 60 strokes per minute and a brushing force of 2.5 N. After 2, 5, 10, and 25 min of toothbrushing, new surface profiles were recorded, and the dentine wear was calculated with a customized computer programme. The dentine wear of human and bovine dentine within the four groups was compared with unpaired t tests. No statistically significant difference was recorded for the dentine wear of human and bovine samples within the different groups.

Objective: To investigate the effect of various fluoride compounds and casein phosphopeptide/amorphous calcium phosphate (CPP-ACP) on the reduction of erosive/abrasive tooth wear., Methods: Forty enamel samples were prepared from bovine lower incisors, stratified and allocated to 4 groups (1-4). Samples in group 1 remained untreated and served as negative controls. The test samples were treated for 2 min/day as follows: group 2 amine/sodium fluoride gel (pH 4.8; 12,500 ppm), group 3 sodium fluoride gel (pH 7.1; 12,500 ppm) and group 4 CPP-ACP-containing mousse. De- and remineralization cycling was performed for 20 days with 6 erosive attacks for 20 s with HCl (pH 3.0) per day. Samples were stored in artificial saliva between cycles and overnight. Toothbrushing (15 s; 60 strokes/min; load 2.5 N) with a toothpaste slurry was performed each day before the first and 1 h after the last erosive exposure. Tooth wear was measured by comparing baseline surface profiles with the corresponding posttreatment profiles., Results: Tooth wear was significantly reduced in groups 2 and 3 compared with group 1, while the enamel loss of group 4 was not significantly lower compared to the negative control group 1. Between the fluoride groups 2 and 3, no significant difference in tooth wear was recorded., Conclusion: Erosive/abrasive tooth wear under the conditions used could be reduced significantly by the daily application of fluoride gels, irrespective of the fluoride compound, while the application of CPP-ACP-containing mousse was less effective., (Copyright 2010 S. Karger AG, Basel.)

Objectives: The aim of this study was to investigate the effects of erosion and toothbrush abrasion on different restorative materials and human enamel., Methods: Human enamel and 5 kinds of tooth-colored restorative materials were used. The restorative materials included three composite resins (Filtek Silorane, Tetric EvoCeram, and Tetric EvoFlow), a polyacid-modified composite (Dyract Extra), and a conventional glass-ionomer cement (Ketac Fil Plus). For each type of the material, 40 specimens were prepared and embedded in ceramic moulds and divided into four groups (n=10): control group (C), erosion group (E), abrasion group (A), and erosion-abrasion group (EA). The specimens were subjected to six daily erosive attacks (groups E and EA; citric acid, pH 2.3, 1 min) and/or six abrasive attacks (groups A and EA; toothbrush abrasion, 100 strokes, 1 min), while the control specimens (group C) were maintained in artificial saliva. After 10-day treatment, the substance loss and surface changes were determined by surface profilometry and scanning electron microscopy., Results: Human enamel presented higher substance loss when compared to restorative materials. Generally, combined erosion-abrasion (EA) caused the highest substance loss, followed by erosion, abrasion, and storage in artificial saliva. Composite resin presented highest durability under erosive and/or abrasive attacks. Enamel and restorative materials showed degradation in groups E and EA through SEM observation., Conclusions: Toothbrush abrasion has a synergistic effect with erosion on substance loss of human enamel, polyacid-modified composite and glass-ionomer cement. The acid- and abrasive-resistance of human enamel was lower compared to restorative materials.

Objective: To determine the association between KOH-soluble and structurally bound fluoride uptake and the erosion resistance of enamel, respectively. Additionally, the effect of enamel pre-treatment with ethanol before fluoridation was assessed., Methods: Sixty bovine incisors (4 specimens/tooth) were randomly allocated to six groups (A-F). Samples 1 and 2 remained untreated, serving as control at baseline. Pre-treatment of the samples was performed for 5 min with 99% ethanol (groups A, B and C) or physiologic saline (groups D, E and F). Samples 3 and 4 were treated either with 0.5% (groups A and D), 1.0% (groups B and E) or 1.5% (groups C and F) fluoride solution. In samples 1 and 3, uptake of KOH-soluble and structurally bound fluoride was determined. Samples 2 and 4 were used for the determination of acid susceptibility by immersion in 1 ml HCl for 30s. Calcium release into HCl was assessed by atomic absorption spectroscopy. Differences between the groups were calculated by unpaired t-tests (p<0.05)., Results: Mode of pre-treatment showed no influence on fluoride acquisition. KOH-soluble and structurally fluoride uptake increased with increasing fluoride concentrations. Highest acid resistance was observed after treatment with 1% fluoride solution for both kinds of pre-treatment followed by 1.5% and 0.5% fluoride solution., Conclusion: Dose-dependency was observed for enamel fluoride acquisition but not for acid resistance.