Dental erosion is a growing health problem linked to the exceptional increase in the consumption of soft drinks, fruit juices, and sport drinks in many countries including Bangladesh. Dental erosion is the chemical dissolution of the dental hard tissues by acids without the involvement of microorganisms. Hydrogen ions (H + ) from acidic solutions can replace the calcium ions (Ca 2+ ) of the enamel, consequently breaking the crystal structure of the enamel and initiating dental erosion. Erosive tooth wear can lead to severe impairment of esthetics along with loss of hardness and functionality. Sources of the erosive acidic challenges can be intrinsic (i.e., gastroesophaegal reflux disease) and/or extrinsic (i.e., exposure from acidic foods and beverages). Continuous intake of drinks or food with pH lower than the critical erosive pH of enamel (5.2-5.5) and root dentin (~6.7) are considered to be responsible for dental erosion. Drinks with low pH and high titratable acidity (TA) have more potential to dissolved enamel and root dentin; on the other hand, drinks with low degree of saturation can stimulate leaching of minerals. In Bangladesh, there is limited scientific information available to assess the potential of dental erosion of the commercially available beverages and drinking water. This research aims to characterize the dental erosion potential of soft drinks, energy drinks, fruit juices, and bottled drinking water available in Bangladesh by determining their pH, TA, calcium (Ca 2+ ), and phosphate (PO 4 3− ). The degrees of saturation of the selected samples were calculated from the experimental results of pH, calcium, and phosphate levels. Soft drinks were found to have high erosion potential followed by energy drinks, fruit juices, and bottled drinking water. Most of the beverages locally available were found highly acidic. Phosphate levels were high in black cola drinks. Total TA was highest for the energy drinks, and moderate for soft drinks and fruit juices. Fruit juices contained high level of calcium compared with other beverages. The degree of saturation was moderate for fruit juices, and very low for few of the soft drinks and most of the bottled drinking waters. This study will be useful as a reference line for the health professionals and regulatory authorities for quality control of the beverages and bottled drinking water available in the local market. ARTICLE HISTORY

The aims of this study were 1) to determine whether the Compare software Comparison% score provided appropriate feedback for preparation depth on a non-anatomical tooth and 2) to define an acceptable tolerance for use in calculating the Comparison% for virtual assessment of cavity depth on a non-anatomical mandibular first molar. Forty-six non-anatomical ivorine teeth with laser-marked outlines on their occlusal surfaces were used for this study. One tooth was prepared at a 1.5 mm depth, approved by participating faculty at a U.S. dental school, and served as the standard preparation. The remaining teeth were divided into three groups (n=15 per group) for cavity preparation depths of 1 mm, 1.5 mm, and 2 mm in the laser-engraved external outline. Teeth were prepared using an electric handpiece with a 330 bur and a hatchet. Virtual images of the standard and experimental tooth preparations were recorded using an intraoral scanner. Virtual comparison software was then used to superimpose a three-dimensional (3D) image of each experimental preparation on the 3D image of the standard preparation. The software calculated comparison surface percentage values (Comparison%) at a 100 and 200 micron tolerance for each specimen. Two-way mixed linear models (α=0.01) were adopted to compare outcomes for the two levels of tolerance for teeth with different depths of preparation. Using a tolerance level of 200 μm, Comparison% scores for the acceptable preparation depth of 1.5 mm were found to be significantly different (p<0.01) from those of the unacceptable 1 mm and 2 mm depth preparations. These findings suggest that virtual comparison software may be used to assess an acceptable depth for cavity preparation within a defined external outline.

The aim of this study was to evaluate the impact of a contemporary preclinical technique skills course on early dental student performance in a preclinical operative course. Ivorine teeth prepared for Class I resin restorations by the Classes of 2020 and 2021 in one U.S. dental school were evaluated in this study (N=184). Ivorine teeth were prepared during the first practical exam of the operative dentistry course. Students in the Class of 2021 had been enrolled in a contemporary technique skills course a semester prior to the operative dentistry course, while students in the Class of 2020 were not. The preparations were randomly evaluated by three calibrated and blinded faculty members using magnification loupes, an explorer, and a periodontal probe to evaluate external outline form, internal form, depth, and margin following an established rubric. The results showed that students in the Class of 2021 (who had taken the technique skills course) performed significantly better than students in the Class of 2020 for all criteria evaluated (p<0.05). In this study, incorporation of the preclinical technique skills course improved student performance in the subsequent operative dentistry course.

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