The aim of this study was to determine the effect of variations in indentation load and time on the Knoop and Vickers hardness numbers (KHN and VHN) for enamel and dentin. Twenty molar teeth were divided into twenty enamel and twenty dentin specimens. Each specimen was tested using a Knoop or Vickers microhardness tester at different loads and times. The difference in hardness between the groups was analyzed with two-way ANOVA followed by a Tukey test. The results revealed that a difference of indentation time did not influence the microhardness number of enamel and dentin. The KHN values of enamel and the VHN values of dentin were affected by variation of test loads. Therefore, the tooth hardness number for different loads may not be acceptable for comparison.

This study aimed to determine the anti-erosive effects of xylitol, fluoride and a xylitol/fluoride combination used as an additive in an acidic drink or as mouthrinse after enamel was exposed to an acidic drink, in vitro. Human third molars were divided into 7 groups (A-G). Samples from groups A to D were immersed for 5 min in orange juice only (A), orange juice plus either 25% xylitol (B), F(-) 1 ppm (C) or a 25% xylitol/F(-) 1 ppm combination (D), respectively. Samples from groups E to G were immersed in orange juice for 5 min and then in either 40% xylitol (E), F(-) 227 ppm (F) or a 40% xylitol/F(-) 227 ppm combination (G), for 1 min respectively. This process was performed four times daily for 14 days. Mineral loss was determined from the lesion depth and surface hardness. Erosion depth progressively increased in all groups, except E, where erosion depth was significantly lower than group A. Surface microhardness progressively decreased in all groups, except E, where hardness was significantly higher than group A. This study demonstrated that addition of xylitol, fluoride or a xylitol/fluoride combination to an acidic drink or post-treatment with fluoride or a xylitol/fluoride combination could reduce, but not prevent, enamel erosion.

Background/purpose: The purpose of this study was to evaluate how well the pH and titratable acidity (TA) of beverages can predict dental enamel erosion. Materials and methods: The erosive potential of 16 beverages was assessed by measuring their pH and TA. Six beverages were used for training purposes to derive a prediction equation. The ten remaining beverages were set aside to test the prediction equation. Enamel samples were immersed in each beverage for 60 minutes. Enamel loss was measured before and after immersion in different beverages using a profilometer. The equation was formulated from the pH, TA, and enamel loss of the training group. The enamel loss of the test group was calculated using the prediction equation and was compared with the experimental results. Results: Using the prediction equation [enamel loss (mm) Z 6.676 À 1.726 pH þ 0.233 TA], the difference between the calculated enamel loss and experimental enamel loss ranged 3.0e14.6% for these beverages. Conclusions: The erosive potential of several beverages can be predicted by the pH and TA.

The aim of this study was to measure the difference in the erosion depth of enamel measured by profilometry (PM) and a measuring microscope (MM). Sixty enamel specimens were divided into ten groups. Each specimen group was exposed to 50 ml of a carbonated drink with pH 2.38 or orange juice with pH 3.67 for 15, 30, 60, 120, and 180 minutes. Depths of eroded areas were measured with a profilometer and a measuring microscope. Data of average enamel loss were measured by PM and MM for all erosion times and were scatter plotted on a graph with regression fit. Correlations between the enamel loss measured by PM and MM were analyzed with a paired sample t-test to compare the discriminatory abilities of the two methods of analysis for all erosion times. The regression fit in all study cases showed a high linear relationship (R(2) = 0.90) between measurements by PM and MM, but in cases where the erosion depth was lower than the depth of focus (DOF) of the MM objective lens, there were weak correlation coefficients (-0.007 - 0.303) for comparison between the two measurement methods.

The purpose of this study was to evaluate the flexural properties and surface topography of fiber posts surface-treated with various etching protocols. Seventy each of three types of fiber posts: RelyX Fiber Post, Tenax Fiber Trans, and D.T. Light-Post Illusion X-Ro, were randomly divided into 7 groups: no surface treatment, surface treated with hydrofluoric acid (HF) 4.5% for 60 s, HF 4.5% for 120 s, HF 9.6% for 15 s, HF 9.6% for 60 s, HF 9.6% for 120 s, and treated with H2O2 24% for 10 min. The specimens were then subjected to a three-point bending test. Surface topographies of the posts were observed using a SEM. The results indicate that fiber post surface pretreatments had no adverse effects on the flexural properties. However, the fiber posts treated with high HF concentrations or long etching times seemed to have more surface irregularities.

Eighty per cent of patients sought dental treatment because of symptoms. Age, sex, occupation, and distance were associated with the utilisation of dental services.

The aim of this study was to determine the extent to which fermented shrimp paste (which has a high calcium concentration) reduces dental erosion in vitro. In experiment 1, enamel specimens were exposed to various concentrations of shrimp paste in tamarind juice for 15 min, once a day, for a total of 29 days. In experiment 2, pre-softened enamel specimens were exposed to different concentrations of shrimp paste in water, using an exposure method similar to experiment 1. Profilometry and a microhardness test were used to assess changes in enamel loss and softening. The results showed that shrimp paste can reduce the erosive potential of tamarind juice and re-harden softened enamel.