Dentin Erosion Research Articles

The Effect of Salivary Factors on Dental Erosion in Various Age Groups and Tooth Surfaces

Saliva, tooth experiences and tooth position may be associated with dental erosion. To identify factors that may provide a potential protective effect against erosion, the authors compared salivary factors and behavioral aspects in participants in three age groups. The authors evaluated 79 volunteer participants in three age groups: 16 through 20 years, 26 through 30 years and 46 through 50 years. They classified all teeth as having no erosion, having erosion involving only enamel or having erosion involving dentin on at least one surface. They collected saliva from each participant and determined pH, flow rate, buffering capacity, urea, total protein and volume required to neutralize orange juice. Unstimulated salivary buffering capacity and urea concentration in salivary samples of participants aged 16 through 20 years with no erosion (facial/buccal surface) were significantly greater than those in the group with enamel erosion (P < .05). In participants aged 26 through 30 years (occlusal surface), the stimulated salivary flow rate was higher in the group with enamel erosion than in the group with dentin erosion (P < .05). In the group aged 46 through 50 years (lingual and palatal surfaces), only stimulated salivary total protein was significantly higher in the group with enamel erosion (P < .05). In groups aged 16 through 20 years and 46 through 50 years, erosion appeared to be related to a preference for sour (acidic) tastes (P < .05). Saliva protects enamel and dentin from erosion. Its effectiveness in this role depends partly on salivary factors and may differ according to a person's age and to the severity and site of erosion. Salivary factors including flow rate, urea, buffering capacity and neutralization capability help prevent dental erosion. The protective level of saliva varies by age and tooth experiences.

The effect of casein phosphopeptide-amorphous calcium phosphate on erosive dentine wear

The effect of casein phosphopeptide-amorphous calcium phosphate on erosive dentine wear

The effect of different concentrations of EDTA on instrumented root canal walls

The purpose of this study was to investigate smear layer removal and erosive capacity of different concentrations of EDTA on instrumented root canal walls. Forty single-rooted teeth were instrumented using step-back technique and 2.5% NaOCl. The teeth were randomly divided into 4 groups, and final flushes were preformed with different concentrations of EDTA (15%, 10%, 5%, and 1%). All specimens were prepared for scanning electron microscope evaluation. The results showed that there was no significant difference on the smear layer removal between different concentrations of EDTA (P = .1959). Only coronal versus apical thirds showed significant difference regarding presence of smear layer (P = .0176). Whereas 15%, 10%, and 5% EDTA solutions demonstrated similar erosion patterns on the root canal walls (P > .05), 1% EDTA caused restricted erosion (P < .0001). There was no significant difference among the regions in terms of erosion (P = .6399). Lower concentrations of EDTA can be recommended for clinical usage to avoid excessive erosion of root canal dentin.

TiF 4 and NaF at pH 1.2 but not at pH 3.5 are able to reduce dentin erosion

Objective This study aimed to analyse and compare the protective effect of buffered (pH 3.5) and native (pH 1.2) TiF 4 in comparison to NaF solutions of same pH on dentin erosion. Design Bovine samples were pretreated with 1.50% TiF 4 or 2.02% NaF (both 0.48 M F) solutions, each with a pH of 1.2 and 3.5. The control group received no fluoride pretreatment. Ten samples in each group were eroded with HCl (pH 2.6) for 10 × 60 s. Erosion was analysed by determination of calcium release into the acid. Additionally, the surface and the elemental surface composition were examined by scanning electron microscopy (two samples in each group) and X-ray energy-dispersive spectroscopy in fluoridated but not eroded samples (six samples in each group). Cumulative calcium release (nmol/mm 2) was statistically analysed by repeated measures ANOVA and one-way ANOVA at t = 10 min. Results TiF 4 and NaF at pH 1.2 decreased calcium release significantly, while TiF 4 and NaF at pH 3.5 were not effective. Samples treated with TiF 4 at pH 1.2 showed a significant increase of Ti, while NaF pretreatment increased F concentration significantly. TiF 4 at pH 1.2 led to the formation of globular precipitates occluding dentinal tubules, which could not be observed on samples treated with TiF 4 at pH 3.5. NaF at pH 1.2 but not at pH 3.5 induced the formation of surface precipitates covering dentinal tubules. Conclusion Dentin erosion can be significantly reduced by TiF 4 and NaF at pH 1.2, but not at pH 3.5.

The effect of casein phosphopeptide‐amorphous calcium phosphate on erosive dentine wear

Erosive tooth wear is a growing concern in clinical dentistry. Our aims were to assess the effect of Tooth Mousse (TM) in managing erosive dentine wear in vitro. Opposing enamel and dentine specimens from 36 third molar teeth were worn under a load of 100 N for 75 000 cycles in electromechanical tooth wear machines. In experiment 1, TM was applied continuously at the wear interface and the mean dentine wear rate was compared with those of specimens subjected to continuous application of hydrochloric acid (HCl, pH 3.0) and deionized water (DW, pH 6.1) as lubricants. In experiment 2, specimens were subjected to TM application every 1600 cycles at both pH 3.0 and 6.1, and the mean dentine wear rates were compared with those of specimens worn with continuous application of HCl and DW lubricants. Dentine wear was reduced significantly with continuous application of TM compared with HCl and DW lubricants. Specimens prepared with continuous TM application displayed smooth wear facets, whereas more pronounced microwear details were observed with HCl and DW lubricants. Both remineralization and lubrication seem to contribute to reduction in dentine wear associated with TM application, although lubrication appears to have a more pronounced effect.

Prevalence of dental erosion and associated drinks in 12-year-old population of Beijing

To investigate the prevalence of dental erosion and associated drinks in 12-year-old adolescence of Beijing. A random sample of 12-year-old adolescence of Beijing (n=844) was examined for dental erosion and required to fill a questionnaire of acidic drink intake. The grade criteria suitable for the survey of the dental erosion was used in the study. The prevalence of dental erosion was 61.8%, of which mild enamel was 74.1%, severe enamel erosion 24.9% and dentine erosion 1.0%. Statistic analysis showed that a large amount of intake of carbonated drink or juice were risk factors. Attention should be paid to the prevalence of dental erosion among Chinese adolescence.

The effect of casein phosphopeptide–amorphous calcium phosphate on erosive enamel and dentine wear by toothbrush abrasion

Objective In addition to its role as a remineralizing agent in preventing dental caries, calcium product (CPP–ACP) delivered as a mousse (Tooth Mousse ®, TM) can reduce erosion of enamel and dentine. The aim of this study was to determine whether CPP–ACP could also reduce erosive tooth wear involving toothbrush abrasion. Methods Flat, polished enamel and dentine specimens ( n = 72) were subjected to 10 wear regimes, with each regime involving erosion in 0.3% citric acid (pH 3.2) for 10 min followed by toothbrush abrasion in a slurry of fluoride-free toothpaste and artificial saliva (1:3 ratio by weight) under a load of 2N for 200 cycles. The specimens were immersed in artificial saliva for 2 h between wear regimes. In the experimental group 1, TM (containing CPP–ACP) was applied at the beginning of each wear episode for 5 min whereas TM− (without CPP–ACP) was applied in the experimental group 2. No mousse was applied in the control group. Results TM significantly reduced enamel wear (mean ± S.E., 1.26 ± 0.33 μm in the experimental group 1 vs 3.48 ± 0.43 μm in the control group) and dentine wear (2.16 ± 0.89 μm in the experimental group 1 vs 10.29 ± 1.64 μm in the control group), and dentine wear was significantly less in the experimental group 1 than in the experimental group 2 (5.75 ± 0.98 μm). Conclusion The finding that TM reduced erosive tooth wear involving toothbrush abrasion, probably by remineralizing and lubricating eroded tooth surfaces, may have implications in the management of tooth wear.

The Role of Saliva in Dental Erosion and a Prosthetic Approach to Treatment: A Case Report

The aim of this report is to describe the relationship of some salivary parameters to dental erosion resulting from excessive citric acid consumption and present a description of a prosthetic approach used to restore the damaged dentition of a patient with severe erosion. The high consumption of dietary sources of acids can lead to erosion or the excessive wear of dental hard tissues. Erosion may be modified by salivary parameters such as flow rate, pH, and buffering capacity. Porcelain-fused-to-metal (PFM) restorations and composite resin veneers can be used successfully to restore impaired esthetics and eliminate tooth hypersensitivity in such cases. A 37-year-old woman with a history of excessive lemon consumption presented with a complaint of tooth hypersensitivity and the poor appearance of her dentition due to erosion. Stimulated and unstimulated salivary samples of the patient were evaluated for flow rate, pH, and buffering capacity before and after treatment. The pre-treatment values were found to be higher than post-treatment values. Stimulated samples showed an increase of salivary flow rate, pH, and buffering capacity. The measured parameters put forth the defensive potential of saliva against the acidic diet, and the salivary flow rate and buffering capacity decreased after reducing acidic consumption. The excessively eroded teeth were restored using PFM restorations whereas the superficially eroded teeth were restored with composite resins. The introduction of acidic foods, beverages, or other agents can exceed the natural buffering capacity of saliva. The result is a lowering of the pH of the oral environment which can lead to erosion of enamel and dentin. Loss of tooth structure due to erosion can compromise the esthetics of the dentition and lead to hypersensitivity of the teeth. Teeth damaged by erosion can be successfully restored by composite resin or porcelain restorations and esthetics and function of dentition can be improved. This report is a profound example of how the over consumption of acidic agents affect not only dental tissues but also the chemical balance of the oral environment as well as the oral habitat.

Effect of Nd:YAG Irradiation and Fluoride Application on Dentine Resistance to Erosionin Vitro

In this paper we evaluated the effect of two fluoridated agents and Nd:YAG irradiation separately and in combination on dentine resistance to erosion. The morphological changes in dentin induced by laser treatment may reduce the progression of erosive lesions. Due to the possibility of a synergistic effect of laser with fluoride, this study was conducted. Eighty bovine dentine samples (4 x 4 mm) were randomly divided into eight groups, according to the following treatments: G1: untreated (control); G2: acidic phosphate fluoride gel (APF 1.23%) for 4 min; G3: fluoride varnish (NaF 2.26%) for 6 h; G4: 0.5 W Nd:YAG laser (250 microsec pulse, 10 Hz, 35 J/cm2, 30 sec); G5: 0.75 W Nd:YAG laser (52.5 J/cm2); G6: 1.0 W Nd:YAG laser (70 J/cm2); G7: APF + 0.75 W Nd:YAG laser; and G8: NaF + 0.75 W Nd:YAG laser. After the treatments, half of each dentine surface was protected with nail varnish. The samples were stored in artificial saliva (30 mL/sample) for 24 h and submitted to four erosive 1-min cycles. Between the erosive attacks, the blocks were maintained in artificial saliva for 59 min. The erosive wear was evaluated by profilometry. The mean wear (+/-SD, microm) was: G1: 1.20 +/- 0.20; G2: 0.47 +/- 0.06; G3: 0.81 +/- 0.11; G4: 1.47 +/- 0.32; G5: 1.52 +/- 0.24; G6: 1.49 +/- 0.30; G7: 0.49 +/- 0.11; and G8: 1.06 +/- 0.31 (Tukey's test, p< 0.05). Laser irradiation was not able to reduce dentine erosion. However, fluoride application was able to increase the dentine's resistance to erosion, and APF showed better results than fluoride varnish.

TSG-6 Regulates Bone Remodeling through Inhibition of Osteoblastogenesis and Osteoclast Activation

TSG-6 is an inflammation-induced protein that is produced at pathological sites, including arthritic joints. In animal models of arthritis, TSG-6 protects against joint damage; this has been attributed to its inhibitory effects on neutrophil migration and plasmin activity. Here we investigated whether TSG-6 can directly influence bone erosion. Our data reveal that TSG-6 inhibits RANKL-induced osteoclast differentiation/activation from human and murine precursor cells, where elevated dentine erosion by osteoclasts derived from TSG-6-/- mice is consistent with the very severe arthritis seen in these animals. However, the long bones from unchallenged TSG-6-/- mice were found to have higher trabecular mass than controls, suggesting that in the absence of inflammation TSG-6 has a role in bone homeostasis; we have detected expression of the TSG-6 protein in the bone marrow of unchallenged wild type mice. Furthermore, we have observed that TSG-6 can inhibit bone morphogenetic protein-2 (BMP-2)-mediated osteoblast differentiation. Interaction analysis revealed that TSG-6 binds directly to RANKL and to BMP-2 (as well as other osteogenic BMPs but not BMP-3) via composite surfaces involving its Link and CUB modules. Consistent with this, the full-length protein is required for maximal inhibition of osteoblast differentiation and osteoclast activation, although the isolated Link module retains significant activity in the latter case. We hypothesize that TSG-6 has dual roles in bone remodeling; one protective, where it inhibits RANKL-induced bone erosion in inflammatory diseases such as arthritis, and the other homeostatic, where its interactions with BMP-2 and RANKL help to balance mineralization by osteoblasts and bone resorption by osteoclasts.

A Longitudinal Study of Tooth Erosion in Adolescents

Incidence studies on tooth erosion among adolescents are scarce. This longitudinal study aimed at estimating the prevalence, incidence, progression, and distribution of erosion in young adolescents over a 1.5-year period. Erosion at baseline was present in 32.2% of the 622 children (mean age, 11.9 +/- 0.9 yrs) and increased to 42.8% over 1.5 yrs. The prevalence of deep enamel or dentin erosion increased from 1.8% to 13.3%. It was hypothesized that more boys will suffer from erosion than girls. At baseline, no difference was found (p = 0.139), whereas 1.5 yrs later, more boys showed erosion than girls (p = 0.026). Of the erosion-free children, 24.2% developed erosion. Progression of erosion in terms of lesion depth and/or in number of lesions was 61.0% and was found more frequently in boys than in girls (p = 0.034). The distribution of erosion showed a predominance of occlusal surfaces of molars, especially the mesiobuccal cusp top, and palatal surfaces of upper anterior teeth.

Protective Effect of Different Tetrafluorides on Erosion of Pellicle-Free and Pellicle-Covered Enamel and Dentine

The aim was to analyze the protective effects of titanium, zirconium and hafnium tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine in vitro. Eight groups of 20 specimens each of bovine enamel and bovine dentine were prepared. Half the specimens in each group were immersed in human saliva for 2 h for pellicle formation. Specimens were then left untreated (controls) or were treated for 120 s with TiF₄, ZrF₄ or HfF₄ solutions (0.4 or 1%) or 1.25% AmF/NaF gel. All specimens were eroded by exposure to hydrochloric acid, pH 2.6, for 25 min. Cumulative calcium release into the acid was monitored in consecutive 30-second intervals for 5 min, then at 2-min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were analyzed by ANOVA. 1% TiF₄ solution offered the best protective effect, especially in dentine (reduction of calcium loss about 50% at 25 min). 1% ZrF₄, 1% HfF₄ and 0.4% TiF₄ also reduced calcium loss, but to a lesser extent. Long-term effects were limited to dentine, while reduction of enamel erosion (about 25%) was restricted to 1-min erosion. The fluoride gel had a protective effect only in dentine. The efficacy of the tetrafluorides was influenced by the presence of the pellicle layer, in that the protection against dentine erosion by TiF₄ and ZrF₄ was greater on pellicle-covered specimens. Tetrafluoride solutions, especially 1% TiF₄, could decrease dental erosion, but were more effective on dentine than on enamel.

Strong effect on dentin after the use of high concentrations of citric acid: An assessment with co-site optical microscopy and ESEM

Objectives To perform a longitudinal analysis of the effect of four substances (citric acid at 1%, 5% and 10% concentrations and 17% EDTA) on dentin. Methods Sixteen human molars had their crowns removed exposing cervical root dentin. A grinding procedure was used to produce a standardized smear layer and to create a smooth surface for analysis. Environmental scanning electron microscopy (ESEM) was used for qualitative observations while co-site optical microscopy (CSOM) and image analysis (IA) provided a quantitative comparison of the effect of the substances for several experimental times from 15 to 300 s. The methods allowed the observation of the same areas after each experimental time. The open tubule area fraction was measured for several CSOM image fields, at each experimental time, for the four substances. Thus, it was possible to follow the phenomenon and quantitatively analyze the effect of the substances. Kolmogorov–Smirnov, Kruskal–Wallis H and Wilcoxon signed-ranks (with Bonferroni correction) tests were used to analyze the data. The level of significance was set at p < 0.05. Results The CA solutions showed the greatest chelating effect, which was proportional to concentration (EDTA: 9.4–32.8% (15–300 s); 1% CA: 21.1–32.2% (15–300 s); 5% CA: 32.4–43.1% (15–300 s); 10% CA: 35.1–39.5% (15–30 s). Erosive effects were observed on inter and peritubular dentin for 5% CA and 10% CA after 60 s. Significance ESEM allowed a detailed qualitative comparison of the effect of the four substances. CSOM and IA provided a quantitative comparison method with good statistical significance. Future studies should focus on the consequences of dentin erosion caused by citric acid.

Effect of Different Concentrations of Fluoride in Dentifrices on Dentin Erosion Subjected or Not to Abrasion in situ/ex vivo

This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion ex vivo in a cola drink (60 s, pH 2.6) 4 times daily. During this step, the volunteers brushed their teeth with one of three dentifrices D (5,000 ppm F, NaF, silica); C (1,100 ppm F, NaF, silica) and placebo (22 ppm F, silica). Then, the respective dentifrice slurry (1:3) was dripped on dentin surfaces. While no further treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced in the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Bonferroni test (a = 0.05). Dentin loss after erosive-abrasive wear was significantly greater than after erosion alone. Wear was significantly higher for the placebo than for the D and C dentifrices, which were not significantly different from each other. It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to reduce dentin wear by erosion and erosion + abrasion, but the protective effect does not increase with fluoride concentration.

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 (α=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.

The Effect of Saliva Derived from Different Individuals on the Erosion of Enamel and Dentine

The aim of this study was to determine if saliva from 14 subjects afforded different levels of protection to human enamel and dentine against erosion in vitro. Test specimens were exposed for 2 h to saliva and control specimens to water for 2 h followed by citric acid for 10 min. This cycle was carried out 12 times. Tissue loss measured by contact profilometry was highly significantly different between subjects. Erosion was significantly reduced by pre-treatment with saliva from 7 subjects (enamel) or 6 subjects (dentine). Saliva from 1 subject resulted in significantly more enamel erosion than control. Conclusion: Saliva from different donors affords different levels of protection against erosion.

Effect of olive oil and an olive-oil-containing fluoridated mouthrinse on enamel and dentin erosion in vitro

Objective. The study aimed to analyse the impact of olive oil and an olive-oil-containing fluoridated mouthrinse on enamel and dentin erosion. Material and Methods. Bovine enamel and dentin specimens were submitted to 10 alternating demineralization and remineralization cycles each consisting of 5 min pretreatment with the test solutions, i.e. distilled water as negative control, 100% olive oil, 2% olive oil emulsion, 2% olive-oil-containing mouthrinse (Xerostom®), acidic 13.2 mmol·l−1 (250 ppm) fluoride solution as positive control, storage in artificial saliva (30 min), demineralization in citric acid (3 min, pH 2.3) and again storage in artificial saliva (60 min). Each group contained 10 enamel and dentin samples. Enamel and dentin loss was analyzed by profilometry after 10 cycles. Results. Treatment with 100% olive oil was not effective in reducing enamel and dentin loss. Application of 2% olive oil or the olive-oil-containing mouthrinse also showed protection against erosion, but to a lesser degree compared to the positive control. Conclusion. Olive oil offered protection against enamel and dentin erosion when applied as 2% emulsion or 2% olive-oil-containing mouthrinse, but is not effective when applied as pure oil (100%). However, 2% olive oil emulsion is less effective in reducing erosion compared to the acidic 13.2 mol·l−1 fluoride solution.

Protective effect of the in situ pellicle on dentin erosion–an ex vivo pilot study

Aim The acquired pellicle is well known as an anti-erosive proteinaceous layer on enamel, but its protective properties on dentin have not been investigated in detail until now. The aim of the present ex vivo study was to evaluate the erosive effects on pellicle coated dentin. Methods Bovine dentin slabs were exposed to the oral cavity of one subject for 120 min for in situ pellicle formation. Subsequently, the slabs were incubated with HCl (pH 2.3) in vitro for 5 min and erosive calcium-release was measured photometrically. In addition, the acid treated specimens were evaluated by transmission electron microscopy (TEM). Pellicle free samples served as controls. Results Calcium erosion from the pellicle coated dentin slabs amounted to 23.5 ± 2.9 μg Ca/min (pellicle free samples: 32.2 ± 4.2 μg Ca/min). The difference was statistically significant ( p ≤ 0.05). In pellicle coated as well as in uncoated dentin samples, TEM-evaluation showed a demineralised dentinal surface layer which thickness ranged between 3 and 6 μm. The pellicle itself was partially dissolved but not removed by hydrochloric acid treatment. Conclusion The protective properties of the acquired pellicle against an erosive challenge of the dentinal surface are limited. The dentinal pellicle functions like an ion permeable network rather than a barrier.

Effect of an iron mouthrinse on enamel and dentine erosion subjected or not to abrasion: An in situ/ ex vivo study

Objectives This in situ/ ex vivo study evaluated whether a rinse with an iron solution could reduce wear and the percentage of microhardness change of human enamel and dentine submitted to erosion followed by brushing after 1 or 30 min. Design During 2 experimental 5-day crossover phases (wash-out period of 10 days), 10 volunteers wore intraoral palatal devices, with 12 specimens (6 of enamel and 6 of dentine) arranged in 3 horizontal rows (4 specimens each). In one phase, the volunteers immersed the device for 5 min in 150 mL of cola drink, 4 times a day. Immediately after immersion, no treatment was performed in one row. The other row was brushed after 1 min using a fluoride dentifrice and the device was replaced into mouth. After 30 min, the remaining row was brushed. In the other phase, the procedures were repeated, but after immersion the volunteers rinsed for 1 min with 10 mL of a 10 mM ferrous sulphate solution. Changes in surface microhardness (%SMH) and wear (profilometry) of enamel and dentine were measured. Data were tested using ANOVA and Tukey's tests ( p < 0.05). Results The enamel presented more wear than dentine, under all experimental conditions. The iron solution caused a significant reduction on the %SMH in enamel, and a significant reduction on the wear in dentine, regardless the other conditions. Conclusions Rinsing with an iron solution after an erosive attack, followed or not by an abrasive episode, may be a viable alternative to reduce the loss of dental structure.

Impact of the acid flow rate on dentin erosion

The study aimed to evaluate the erosive effects of acids flowing with different velocities and duration on dentin previously pre-treated with distilled water or human saliva. Bovine dentin surfaces were submitted to a 10 min demineralisation with hydrochloric or citric acid (pH 2.3, 37 degrees C) in an artificial mouth at flow rates of 3, 2.25, 1.5, 0.75 or 0.15 ml/min or in 30 ml of the respective acid without movement (each subgroup n=16 specimens). Prior to the demineralisation, half of the specimens of each group were either pre-treated with distilled water or human saliva for 120 min. After 2, 5 and 10 min demineralisation, profilometric traces of dentin loss were performed perpendicular to the direction of acid flow at three sites (A-C) with intervals of 500 microm. The first profile (A) was taken in a distance of 1.5 mm from the acid starting to flow over the sample. Thus, median dentin loss at each site was calculated and statistically analysed by five-way ANOVA. Dentin loss increased with increasing acid flow rate and demineralisation time and was higher for demineralisation with citric acid compared to hydrochloric acid. For given flow rates of 0.15 to 3 ml/min, measurement of dentin loss yielded highest values for site A and decreasing values for sites B and C. For all groups, no significant differences of dentin loss were observed between specimens pre-treated with distilled water or human saliva. Under the conditions of this study, both duration of demineralisation and acid flow rate but not pre-treatment with distilled water or saliva influence the extent of dentin erosion.