Galyan Gayatri, Padda Bhupinder Kaur, Kaur Taman Preet, Sharma Mehak, Kapur Ishita, Kaur Sunpreet
Department of Conservative Dentistry and Endodontics, M.M. College of Dental Sciences and Research, Mullana, Ambala, Haryana, India.
Department of Conservative Dentistry and Endodontics, Hazaribag College of Dental Sciences and Hospital, Hazaribag, Jharkhand, India.
J Contemp Dent Pract. 2019 May 1;20(5):566-570.
The aim of the study is to evaluate fracture resistance of nanocomposites with and without fiber reinforcement with different cavity designs used for obliquely fractured incisal edge restoration.
In the present study, 60 sound extracted maxillary central incisors were mounted on autopolymerizable acrylic resin up to the cementoenamel junction, out of which, 10 intact teeth were kept as control (group 1) and the remaining 50 samples were reduced incisally in an oblique manner up to 3 mm. All incisally reduced samples were divided into five groups ( = 10) based on the restoration techniques as follows: group 2 (conventional bevel), group 3 (single central palatal slot on the incisal edge), group 4 (single palatal slot with central 2 mm fiber), group 5 (two palatal slots on the incisal edge with a distance of 0.5 mm to 1 mm between them), and group 6 (two slots on the incisal edge with two 2 mm fibers). All samples were built incrementally with nanocomposites followed by finishing and polishing. All samples including control were then stored in distilled water before their fracture resistance was measured using a universal testing machine. Failure modes were visually examined and the results were subjected to statistical analysis.
The mean fracture resistance among the experimental groups was observed, group 4 with single fiber in the central position had the highest (832.68 N) followed by group 3 (490.84 N), group 5 (446.175), and group 2 (270.1359), and the least in group 6 (223.443). The mean fracture resistance of group 4 is comparable to intact teeth, i.e., group 1 (1096.40). The mean of all samples was compared using the one-way Anova test, and it was found that there is statistically significant difference in fracture resistance among groups ( < 0.001**).
Fibers certainly have the reinforcing effect and the position of fibers determines their reinforcing effects. A single central slot with fiber (Ribbond) showed maximum fracture resistance almost equivalent to natural teeth. Modifying conventional beveled cavity design with an additional slot in the center also increases the fractural strength of restoration.
Nanocomposites reinforced with single fiber in the central palatal slot used for restoring fractured incisors provide strength almost equivalent to natural teeth. In case when the fiber is not available for preparing a single palatal slot also, we can increase the fracture resistance.
本研究旨在评估用于修复斜形折断切缘的不同窝洞设计的含纤维增强和不含纤维增强的纳米复合材料的抗折强度。
在本研究中，60颗完整拔除的上颌中切牙被固定在自凝丙烯酸树脂上至牙骨质釉质界，其中10颗完整牙齿作为对照（第1组），其余50个样本切端以斜形方式降低3mm。所有切端降低的样本根据修复技术分为五组（每组n = 10），如下：第2组（传统斜面），第3组（切缘中央单腭侧沟），第4组（中央2mm纤维的单腭侧沟），第5组（切缘两个腭侧沟，间距0.5mm至1mm），第6组（切缘两个沟，含两根2mm纤维）。所有样本用纳米复合材料逐层构建，然后进行修整和抛光。所有样本包括对照样本在使用万能试验机测量其抗折强度之前均储存在蒸馏水中。肉眼观察失败模式，并对结果进行统计分析。
观察到各实验组的平均抗折强度，中央位置有单根纤维的第4组最高（832.68N），其次是第3组（490.84N）、第5组（446.175N）和第2组（270.1359N），第6组最低（223.443N）。第4组的平均抗折强度与完整牙齿即第1组（1096.40N）相当。使用单因素方差分析对所有样本的平均值进行比较，发现各组之间的抗折强度存在统计学显著差异（P < 0.001**）。
纤维确实具有增强作用，纤维的位置决定其增强效果。带有纤维（Ribbond）的中央单沟显示出最大抗折强度，几乎与天然牙相当。在传统斜面窝洞设计中央增加一个沟也可提高修复体的抗折强度。
用于修复折断切牙的中央腭侧沟内有单根纤维增强的纳米复合材料提供的强度几乎与天然牙相当。如果也无法获得纤维来制备单腭侧沟，我们也可以提高抗折强度。
