Department of Restorative Dentistry, University of North Parana, Londrina, Brazil.
Department of Dentistry, University Paranaense, Umuarama, Brazil.
Dent Traumatol. 2021 Apr;37(2):256-263. doi: 10.1111/edt.12618. Epub 2020 Dec 12.
BACKGROUND/AIMS: Traumatic dental injuries are highly prevalent and are considered an important health problem. The aim of this study was to evaluate the in vitro stress distribution around simulated traumatized teeth subjected to different types of splints by photoelastic analysis.
For each group, five models of maxillary and mandibular arches were made in photoelastic resin using prefabricated teeth models, which were fixed and adjusted in a semi-adjustable articulator. All splints were bonded with composite resin on the labial surfaces of the maxillary central incisors, the lateral incisors and the canine teeth, simulating trauma to the 11. The groups were divided according to the type of splint: control-without splint; rigid-brackets and 0.021 × 0.025 inch stainless steel wire; semi-rigid-brackets and 0.016 × 0.016 inch cobalt-chromium wire; fiber-fiberglass ribbon; and flexible-nylon thread. The groups were submitted to an occlusal force in a special device attached to a universal test machine in balanced, protrusive, and lateral occlusions. Then, the incisal edge of the 11 was ground to simulate infra-occlusion, and the tests were performed again. Five points were analyzed around tooth 11 with a polariscope, and the data were submitted to ANOVA and Tukey tests at a 5% level of significance.
When centric occlusion was analyzed by comparing normal occlusion to infra-occlusion, all groups showed high stress values in infra-occlusion with statistical differences-except for the control group. When lateral occlusion was analyzed, the nylon splint showed lower statistical differences compared with the control, fiberglass, and rigid splint groups, which did not differ between each other. The semi-rigid splint did not differ from any group.
Fiberglass and semi-rigid splints showed better stress distribution around the traumatized tooth under occlusal loads. The nylon splint showed characteristics of non-stress distribution.
背景/目的：外伤性牙损伤的发病率很高，被认为是一个重要的健康问题。本研究的目的是通过光弹分析评估不同类型夹板固定模拟外伤性牙齿时的体外应力分布。
对于每组，使用预制牙齿模型在光弹树脂中制作五个上颌和下颌弓模型，然后在上半可调节关节器上固定和调整。所有夹板均通过复合树脂粘结在上颌中切牙、侧切牙和尖牙的唇面，模拟 11 牙外伤。根据夹板类型将组分为：对照组-无夹板；刚性托槽和 0.021×0.025 英寸不锈钢丝；半刚性托槽和 0.016×0.016 英寸钴铬丝；纤维玻璃纤维带；和弹性尼龙线。将各组置于特殊装置中，通过万能试验机在正中、前伸和侧方咬合时施加咬合力。然后，磨除 11 的切缘以模拟亚咬合，再次进行测试。在偏振光镜下分析牙 11 的五个点，将数据进行方差分析和 Tukey 检验，置信度为 5%。
当比较正中咬合与亚咬合时，所有组在亚咬合时都显示出高的应力值，除对照组外均具有统计学差异。当分析侧方咬合时，与对照组、玻璃纤维和刚性夹板组相比，尼龙夹板显示出较低的统计学差异，而这些组之间没有差异。半刚性夹板与任何组都没有差异。
玻璃纤维和半刚性夹板在咬合负荷下对受伤牙齿的应力分布更好。尼龙夹板显示出非应力分布的特性。
