การเปลี่ยนแปลงพื้นผิวและความแข็งผิวของผิวเคลือบฟันและวัสดุบูรณะฟันหลังจากสัมผัสกับสภาวะความเป็นกรดและการแปรงฟัน (การศึกษาในห้องปฏิบัติการ)

Abstract

Introduction: Tooth and restorative materials exposed to the complex oral environment. One of these environment is acidic food and beverages consumptions. These could affect on tooth surface and restorative materials in the oral cavity. After acidic food consumptions, in the case of toothbrushing has been done consequently, tooth and restorative materials may be altered progressively. Therefore, these may affected on the longevity of tooth and restorative materials. Objectives: This 'in vitro' study was to investigate the effect of acidic conditions and brushing on surface hardness, surface profile changes and scanning electron micrographs. Materials and methods: Human enamel and 3 types of tooth-colored restorative materials were used. These restorative materials included capsulated glass-ionomer cement (FujiR BULK), resin composite (Filtek Z350XT) and ceramic (Feldspathic: Vitablocs Mark II) were used here. For glass-ionomer cement and resin composite, specimens were prepared and embedded in plastic moulds. For enamel and ceramic, the specimens were embedded in self-cured acrylic resin. Before experiment, all specimens were coated with nail varnish in order to provide the testing area of 5×5 mm2 for surface microhardness measurement and 3×5 mm2 for surface profile measurement (Ra and Rz). Surface hardness and surface profile of each specimens were investigated prior to erosion- abrasion cycle as a baseline data. The specimens were immersed in acidic solutions either vinegar or artificial lemon juice for 1 hr. and follow with tooth brushing for 5 min. (150 strokes) with a load of 150 g. Acidic immersion and following with brushing cycle 2d time was done, which meant to complete Erosion-abrasion:A. Surface hardness and surface profile changes were then measured. After Erosion-abrasion:A, the specimens were immersed and brushed again at the same manner for 4 cycles. These meant to finish Erosion-abrasion:B. All specimens were investigated surface hardness, surface profile changes and scanning electron microscope. Surface hardness and surface profile changes were analyzed by Friedman test and Wilcoxon signed ranks test (p<0.05). Results: The mean hardness and surface profile of specimens in each group were measured before experiment were greatly various. These different values depended on compositions of each materials, chemical and physical properties by themselves. Surface hardness of enamel and glass- ionomer cement immersed either vinegar and artificial lemon juice were significantly decreased after Erosion-abrasion:A and progressively reduced after Erosion-abrasion:B when compared with baseline data of each group. Surface hardness of resin composite and ceramic have been showed moderate changes. Surface profile parameter (Ra and Rz) values of enamel and glass-ionomer cement showed the same manner of surface hardness changes whereas resin composite was not significantly changed in both solutions. Scanning electron micrographs showed obviously surface alterations in all groups. Conclusion: Enamel and 3 types of restorative materials immersed in acidic solutions and following with brushing have shown that surface hardness and surface profile have been changed greatly various depend on their chemical and physical properties. In order to investigate erosion and abrasion effect, the experiment should have multiple measurements.