Realigning biomedical science instruction in predoctoral curricula: a proposal for change.

Currently in North America, there is an active dialogue going on about the state of predoctoral dental education and the need for curriculum change, innovation, and the adoption of contemporary, competency-based educational models. At the institutional level, curriculum committees struggle with requests from faculty to add new content to an overburdened didactic and clinic schedule. This article will describe potential solutions centering on the role and scope of the biomedical sciences in predoctoral dental education. The authors propose that dental educators and institutions reconsider the current admission prerequisites and curriculum content of the biomedical sciences in predoctoral programs. The proposed changes are intended to eliminate content redundancy between undergraduate and predoctoral dental education by integration of the biomedical sciences--in particular, biochemistry, microbiology, and physiology--into other clinically oriented coursework and learning experiences in the curriculum based on a pathophysiology model that fosters students' comprehension of the etiology of oral and systemic diseases encountered by the general dental practitioner. The authors explore how changes in the biomedical science prerequisites for dental school matriculation and associated modifications in curriculum focus and content would impact admissions testing, composition of national board exams, and strategies for teaching and learning within dental schools.

Effect of surface roughness on stain resistance of dental resin composites.

BACKGROUND: Surface quality of dental restorations is one of the important factors that determine the success of the restoration. Unfortunately, exterior discoloration is still a problem for dental resin composites. PURPOSE: The purpose of the study was to investigate the influential factors on stain resistance of dental resin composites. MATERIALS AND METHODS: Filtek Supreme (nanocomposite), Filtek A110 (microfilled composite), Filtek Z250 (microhybrid composite), and Filtek P60 (microhybrid composite) (all products from 3M ESPE, St. Paul, MN, USA) were tested. Thirty-six specimens per material were prepared and randomly assigned to 6 groups. The specimens in 5 groups were polished against 1,000-, 1,200-, 1,500-, 2,000-, and 2,500-grit sandpaper, respectively. The specimens in a sixth group were polished with 2,500-grit or 1,200-grit sandpaper and used as controls. Surface roughness (Ra) and gloss of the specimens were measured with a profilometer and a glossmeter, respectively. Specimens were immersed in a coffee solution (control group in distilled water) and kept in a 37 degrees C incubator. Color was measured by a spectrophotometer at baseline, 3 days, 7 days, and 14 days, and color change (DeltaE*(ab)) was calculated. RESULTS: Coffee, material, Ra, and the interaction of material x Ra had statistically significant influences on the stain resistance of the dental composites tested. For most materials in coffee solution, time squared and Ra had significant effects on the discoloration. CONCLUSIONS: Coffee had a significant influence on discoloration of the dental resin composite materials tested. The different composites behaved differently in coffee solution. Discoloration increased as Ra increased for the composites tested, except with Filtek A110. The discoloration process was accelerated with time.

Surface roughness of resin composite prepared by single-use and multi-use diamonds.

PURPOSE: To compare the surface roughness of a resin composite caused by two 30- and 40-microm, multi-use finishing diamonds with two 30- and 40-microm, single-use finishing diamonds of comparable grit size before and after steam sterilization. METHODS: Resin composite specimens 6 mm in diameter and 3 mm in depth were light cured. Surface roughness (Ra, microm) of surfaces formed by Mylar, after finishing with a bur, and after polishing with fine and superfine aluminum oxide disks was measured for the as-received and after sterilization conditions with a surface profilometer. RESULTS: Ra of Mylar surfaces (baseline) ranged from 0.02-0.05 microm. Ra of surfaces prepared with 30-microm diamond burs ranged from 1.42-1.90 microm. Ra of surfaces prepared with 40-microm diamond burs ranged from 2.22-2.42 microm. Ra of surfaces polished sequentially with fine and superfine aluminum oxide disks ranged from 0.07-0.11 microm in the as-received condition and from 0.12-0.14 microm in the sterilized condition. Sterilization and reuse of all types of diamond finishing burs resulted in equal or rougher resin composite surfaces after final polish when compared to final polish surfaces that were initially finished with as-received diamonds. CLINICAL SIGNIFICANCE: Surface roughness of a resin composite prepared with single- and multi-use diamond finishing burs was equivalent when compared at the final polish.

Effect of polishing systems on the surface roughness of microhybrid composites.

PURPOSE: This study was undertaken to examine the effect of three different polishing systems on surface roughness of five newly developed resin composites. MATERIALS AND METHODS: Three microhybrid composites (Point 4, Kerr, Orange, CA; Esthet-X, Dentsply/Caulk, Milford, DE; Vitalescence, Ultradent, South Jordan, UT, USA), one microfilled composite (Renamel Microfill, Cosmedent, Chicago, IL, USA), and one experimental microhybrid composite (FZB, Ivoclar Vivadent, Schaan, Liechtenstein) were light cured with a Mylar strip. Fifteen specimens of each composite (6 mm in diameter and 3 mm in depth) were fabricated and randomly assigned to three groups. Specimens in each group were finished with a carbide bur (16 fluted) and three polishing systems (Astropol, Ivoclar Vivadent; Diagloss, Axis Dental, Irving, TX, USA; Sof-Lex, 3M, ESPE, St. Paul, MN, USA). The average surface roughness (Ra) and the mean peak spacing (Sm) were measured with a surface profilometer after polishing. Five tracings at different locations on each specimen were made. Data were analyzed by analysis of variance. RESULTS: For Astropol, Ra ranged from 0.10 to 0.15 microm and Sm ranged from 24 to 40 microm for the five composites; for Diagloss, Ra ranged from 0.24 to 0.34 microm and Sm from 38 to 74 pm; for Sof-Lex, Ra ranged from 0.06 to 0.10 microm and Sm ranged from 16 to 22 microm. Significant differences between materials and polishing systems were observed. Polishing systems had the most important role in determining the surface roughness of resin composites. CLINICAL SIGNIFICANCE: Of the polished systems tested, Sof-Lex discs provided the lowest roughness for polishing microfilled and microhybrid composites, and the microfilled resin composite showed the lowest roughness.