Does Pigment Incorporation into Regular Composite Resins for Posterior Buildups Alter Their Bond Strength?

Abstract Posterior build-ups are auxiliary devices to orthodontic treatment which are made with resin-based or glass ionomer composites. Their removal requires care to protect the tooth surface, therefore, pigmented materials are preferred for a better visualization. This study proposed a pigmentation experimental technique of a regular composite resin, evaluating the microshear bond strength test (µ-SBT) of this experimental pigmented resin and comparing with a blue-colored polyacid-modified composite resin, used for posterior buildups. Forty-eight buccal and lingual surfaces of human teeth were used and randomly divided into 4 groups (n=12). The groups were divided into: C (control), regular composite resin; P, regular composite resin pigmented; UBL, Ultra Band Lok™; OB, Ortho Bite™. The composites were bonded using a matrix to obtain microcylinders and prepared for each experimental groups. The samples were then stored in distilled water for 24h at 37°C followed by a µ-SBT. The types of bond failures were evaluated using a stereoscopic magnifying glass (10×). The data were analyzed by ANOVA with Fisher post hoc and Dunnett´s test. Means of µ-SBT± standard deviation (MPa) were: C (39.98a±13.0), P (40.09a± 14.3); UBL (33.26ab±8.6); OB (28.70b±5.5). The most prevalent type of failure was adhesive (80.4%). Further, was not observed a statistically significant correlation between the bond strength values and failure patterns. The pigmentation of a commercially available resin did not alter the µ-SBT and exhibited similar adhesiveness as a polyacid-modified composite resin.

后牙垫高垫（posterior buildups）是正畸治疗的辅助装置，由树脂基复合材料或玻璃离聚物复合材料制备而成。其拆除过程需小心操作以保护牙体表面，因此为获得更好的可视性，临床常选用带色素的这类材料。本研究针对普通复合树脂开发了一种染色实验工艺，对该实验性染色树脂的微剪切粘结强度试验（microshear bond strength test，µ-SBT）进行评估，并与一款用于后牙垫高垫的蓝色聚酸改性复合树脂开展对比研究。本研究选取48颗人类恒牙的颊舌面作为样本，随机分为4组（每组n=12）。各组分别为：C组（对照组）：普通复合树脂；P组：染色普通复合树脂；UBL组：Ultra Band Lok™；OB组：Ortho Bite™。各组均通过成型模具制备微圆柱状粘结试件，随后将所有试件置于37℃蒸馏水中储存24小时，再进行微剪切粘结强度试验。采用10倍立体放大镜对粘结失效类型进行评估。采用单因素方差分析（analysis of variance，ANOVA）结合Fisher事后检验与Dunnett检验对数据进行统计学分析。各组微剪切粘结强度均值±标准差（单位：MPa）分别为：C组39.98±13.0（标注字母a）、P组40.09±14.3（标注字母a）、UBL组33.26±8.6（标注字母ab）、OB组28.70±5.5（标注字母b）。最常见的失效类型为粘结界面失效（占比80.4%）。此外，粘结强度数值与失效模式之间未发现具有统计学意义的相关性。普通商用复合树脂经染色处理后，其微剪切粘结强度未发生改变，且与聚酸改性复合树脂的粘结性能相当。