Carlos Lilian Nascimento, Jorge Olivia Santana, Paranhos Luiz Renato, de Freitas Vincenti Sergio Augusto, de Carvalho Panzeri Pires-de-Souza Fernanda
Department of Dental Materials and Prosthodontics, University of São Paulo, Ribeirao Preto School of Dentistry, São Paulo, Brazil.
Department of Dentistry, Federal University of Sergipe, São Cristóvão, Brazil.
Turk J Orthod. 2018 Dec;31(4):110-116. doi: 10.5152/TurkJOrthod.2018.17055. Epub 2018 Dec 1.
The aim of the present study was to compare the shear bond strength (SBS) of orthodontic brackets bonded to the enamel after at-home and in-office bleaching treatments.
Sixty bovine incisors were subjected to initial color readings and then classified into three groups: CP (16% carbamide peroxide), HP (35% hydrogen peroxide), and C (control). After treatments, new color readout was obtained, and orthodontic brackets were bonded to the bleached area. Half of the samples of each group (n=10) were subjected to thermal-mechanical cycling (TMC) testing (1,200,000 cycles; 44.2 N; 2 Hz/s), whereas the other half were stored in distilled water at 37 °C for 24 h. Samples were subjected to the SBS test at a speed of 0.5 mm/min. The mean SBS was analyzed (two-way ANOVA, Bonferroni test, p<0.05), and the fracture patterns were classified as adhesive, cohesive, and mixed types.
There was no difference (p>0.05) in SBS values between the samples subjected to TMC and the cycled samples in any group. Samples subjected to carbamide peroxide presented lower SBS (p<0.05) than the non-cycled ones. Enamel adhesive fractures were higher in the bleached groups than in the control group, which presented mixed fractures prevalence, regardless of whether it was subjected to TMC or not.
Thermal-mechanical cycling was not significant for SBS of orthodontic brackets, but tooth bleaching was a factor.
本研究旨在比较在家用和诊室漂白治疗后正畸托槽与牙釉质之间的剪切粘结强度（SBS）。
对60颗牛切牙进行初始颜色读数，然后分为三组：CP（16%过氧化脲）、HP（35%过氧化氢）和C（对照组）。治疗后，获得新的颜色读数，并将正畸托槽粘结到漂白区域。每组样本的一半（n = 10）进行热机械循环（TMC）测试（1200000次循环；44.2 N；2 Hz/s），而另一半在37℃蒸馏水中保存24小时。以0.5 mm/min的速度对样本进行SBS测试。分析平均SBS（双向方差分析、Bonferroni检验，p < 0.05），并将断裂模式分为粘结型、内聚型和混合型。
在任何组中，进行TMC的样本与循环样本之间的SBS值均无差异（p > 0.05）。用过氧化脲处理的样本的SBS低于未循环样本（p < 0.05）。漂白组的牙釉质粘结性骨折高于对照组，对照组无论是否进行TMC，均以混合型骨折为主。
热机械循环对正畸托槽的SBS无显著影响，但牙齿漂白是一个影响因素。
