Postgraduate student, Department of Restorative Dentistry, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará (UFC), Fortaleza, Ceará, Brazil.
Adjunct Professor, Department of Restorative Dentistry, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará (UFC), Fortaleza, Brazil.
J Prosthet Dent. 2019 Apr;121(4):711.e1-711.e6. doi: 10.1016/j.prosdent.2019.02.001.
Computer-aided design and computer-aided manufacturing (CAD-CAM) has enhanced the physicomechanical stability of ceramics. However, various factors in the oral cavity may impair the longevity of restorations by negatively affecting their properties. Appropriate surface treatments such as glaze application or mechanical polishing are necessary to diminish these effects.
The purpose of this in vitro study was to evaluate the influence of common beverages and toothbrushing on the surface roughness, microhardness, and color stainability of a vitreous CAD-CAM lithium disilicate ceramic with a glazed or mechanically polished surface.
Specimens (N=160) were divided into 2 groups according to the surface treatment method: polishing with abrasive disks or glaze application. Each group was subdivided (n=8) according to the immersion solution and toothbrushing: distilled water and distilled water plus brushing; coffee and coffee plus brushing; black tea and black tea plus brushing; red wine and red wine plus brushing; and cola and cola plus brushing. Before and after simulating a 5-year period of immersion and toothbrushing, a contact profilometer and a Vickers microhardness tester were used to measure the surface roughness and microhardness. CIELab parameters were assessed by using a portable spectrophotometer, and color differences were calculated by using the CIEDE2000 formula (ΔE). Data were compared by using 3-way ANOVA/Bonferroni test for post hoc analysis (α=.05).
Surface roughness increased irrespective of solution (P=.763), being influenced by surface treatment (P<.001), with the glazed groups presenting higher values. Microhardness decrease was influenced by solutions (P<.038) and surface treatment (P<.001), and glazing was associated with lower values. Irrespective of the surface treatment, color stainability was influenced by solutions (P<.001), with ΔE values for red wine being above the perceptibility threshold (ΔE>1.30). No influence of toothbrushing was found for any parameter (P>.05).
Despite its excellent mechanical properties, CAD-CAM lithium disilicate ceramic degraded after exposure to commonly consumed beverages. Irrespective of surface treatment, beverages decreased microhardness and caused color changes. Surface roughness increased, showing higher variation for glazed groups. Toothbrushing was unable to potentiate or diminish the observed effects. In general, the results showed that proper mechanical polishing can produce a surface with desirable properties.
计算机辅助设计和计算机辅助制造（CAD-CAM）提高了陶瓷的物理力学稳定性。然而，口腔中的各种因素可能会通过影响其性能从而降低修复体的寿命。因此，有必要进行适当的表面处理，如上釉或机械抛光。
本体外研究的目的是评估常见饮料和刷牙对上釉或机械抛光的玻璃 CAD-CAM 锂硅陶瓷表面粗糙度、显微硬度和颜色可染性的影响。
将标本（N=160）根据表面处理方法分为两组：用研磨盘抛光或上釉。每组根据浸液和刷牙进一步分为 4 组：蒸馏水和蒸馏水加刷牙；咖啡和咖啡加刷牙；红茶和红茶加刷牙；红酒和红酒加刷牙；和可乐和可乐加刷牙。在模拟 5 年浸泡和刷牙后，使用接触式轮廓仪和维氏显微硬度计测量表面粗糙度和显微硬度。使用便携式分光光度计评估 CIELab 参数，并使用 CIEDE2000 公式（ΔE）计算颜色差异。使用 3 因素方差分析/ Bonferroni 检验进行事后分析（α=.05）比较数据。
无论溶液如何，表面粗糙度均增加（P=.763），受表面处理影响（P<.001），上釉组的数值更高。显微硬度降低受溶液（P<.038）和表面处理（P<.001）影响，上釉与较低的值相关。无论表面处理如何，颜色可染性均受溶液影响（P<.001），红酒的ΔE 值超过可察觉阈值（ΔE>1.30）。刷牙对任何参数均无影响（P>.05）。
尽管 CAD-CAM 锂硅陶瓷具有优异的机械性能，但暴露于常用饮料后会降解。无论表面处理如何，饮料都会降低显微硬度并导致颜色变化。表面粗糙度增加，上釉组的变化更大。刷牙无法增强或减弱观察到的效果。总的来说，结果表明适当的机械抛光可以产生具有理想性能的表面。
