Kiomarsi Nazanin, Saburian Pardis, Chiniforush Nasim, Karazifard Mohammad-Javd, Hashemikamangar Sedighe-Sadat
Assistant professor, Department of operative dentistry, Dental school, Tehran University of Medical Sciences, International campus, Tehran, Iran.
Tehran University of Medical Science, International campus, Tehran, Iran.
J Clin Exp Dent. 2017 Aug 1;9(8):e945-e951. doi: 10.4317/jced.53721. eCollection 2017 Aug.
Repair of composite restorations is a conservative method that can increase the longevity and durability of restorations while preserving the tooth structure. Achieving a suitable bond between the old and new composite is difficult. To overcome this problem, some methods have been recommended to increase the repair bond strength of composite.This study aimed to assess the effect of aging by thermocycling (5,000 and 10,000 cycles) and mechanical surface treatments (Er,Cr:YSGG laser and bur) on repair shear bond strength of composite resin.
Totally, 120 composite blocks measuring 6x4x4 mm were fabricated of Filtek Z250 composite and were randomly divided into three groups (n=40) based on initial aging protocol: (a) no aging: storage in distilled water at 37°C for 24 hours, (b) 5,000 thermal cycles, (c) 10,000 thermal cycles. Each group was then randomly divided into two subgroups (n=20) based on mechanical surface treatment (laser and bur). The laser and bur-prepared surfaces were silanized and Adper Single Bond 2 was then applied. The repair composite was bonded to surfaces. Half of the samples in each subgroup (n=10) were subjected to 5,000 thermal cycles to assess durability of bond. The remaining half were stored in distilled water at 37°C for 24 hours and all samples were then subjected to shear bond strength testing in a universal testing machine with a crosshead speed of 1mm/min. Data (in megapascals) were subjected to one-way ANOVA and Tukey's test (P=0.05). Mode of failure was determined under a stereomicroscope.
Bur preparation significantly improved the bond strength compared to laser (<0.001). Aging by 10,000 thermal cycles significantly decreased the repair bond strength of composite (<0.001). No significant difference was noted in this regard between distilled water and 5,000 thermal cycles groups (=0.699). Primary bond strength and bond strength after 5,000 thermal cycles in the same subgroups were not significantly different either (=0.342).
Aging by 10,000 thermal cycles significantly decreases the repair bond strength of composite and surface preparation by bur provides a higher bond strength compared to laser. Thermocycling, Composite, Repair, Laser.
复合树脂修复体的修复是一种保守的方法，可在保留牙体组织的同时提高修复体的使用寿命和耐久性。在新旧复合树脂之间实现合适的粘结较为困难。为克服这一问题，已推荐了一些方法来提高复合树脂的修复粘结强度。本研究旨在评估热循环（5000次和10000次循环）和机械表面处理（铒铬：钇钪镓石榴石激光和车针）对复合树脂修复体剪切粘结强度的老化影响。
用Filtek Z250复合树脂制作120个尺寸为6×4×4mm的复合树脂块，并根据初始老化方案随机分为三组（n = 40）：（a）未老化：在37°C蒸馏水中储存24小时；（b）5000次热循环；（c）10000次热循环。然后根据机械表面处理（激光和车针）将每组随机分为两个亚组（n = 20）。对激光和车针处理过的表面进行硅烷化处理，然后应用Adper Single Bond 2。将修复复合树脂粘结到表面。每个亚组中的一半样品（n = 10）进行5000次热循环以评估粘结的耐久性。其余一半在37°C蒸馏水中储存24小时，然后所有样品在万能试验机上以1mm/min的十字头速度进行剪切粘结强度测试。数据（以兆帕为单位）进行单因素方差分析和Tukey检验（P = 0.05）。在体视显微镜下确定失效模式。
与激光处理相比，车针处理显著提高了粘结强度（<0.001）。10000次热循环老化显著降低了复合树脂的修复粘结强度（<0.001）。在这方面，蒸馏水组和5000次热循环组之间未观察到显著差异（=0.699）。同一亚组中初始粘结强度和5000次热循环后的粘结强度也无显著差异（=0.342）。
10000次热循环老化显著降低了复合树脂的修复粘结强度，与激光处理相比，车针进行表面处理可提供更高的粘结强度。热循环、复合树脂、修复、激光。
