Department of Prosthetic Dentistry, Faculty of Dentistry, Başkent University, Ankara, Turkey.
J Prosthodont. 2017 Jul;26(5):460-473. doi: 10.1111/jopr.12397. Epub 2015 Nov 30.
Daily consumption of food and drink creates rapid temperature changes in the oral cavity. Heat transfer and thermal stress caused by temperature changes in restored teeth may damage the hard and soft tissue components, resulting in restoration failure. This study evaluates the temperature distribution and related thermal stress on mandibular molar teeth restored via three indirect restorations using three-dimensional (3D) finite element analysis (FEA).
A 3D finite element model was constructed of a mandibular first molar and included enamel, dentin, pulp, surrounding bone, and indirect class 2 restorations of type 2 dental gold alloy, ceramic, and composite resin. A transient thermal FEA was performed to investigate the temperature distribution and the resulting thermal stress after simulated temperature changes from 36°C to 4 or 60°C for a 2-second time period.
The restoration models had similar temperature distributions at 2 seconds in both the thermal conditions. Compared with 60°C exposure, the 4°C condition resulted in thermal stress values of higher magnitudes. At 4ºC, the highest stress value observed was tensile stress (56 to 57 MPa), whereas at 60°C, the highest stress value observed was compressive stress (42 to 43 MPa). These stresses appeared at the cervical region of the lingual enamel. The thermal stress at the restoration surface and resin cement showed decreasing order of magnitude as follows: composite > gold > ceramic, in both thermal conditions.
The properties of the restorative materials do not affect temperature distribution at 2 seconds in restored teeth. The pulpal temperature is below the threshold for vital pulp tissue (42ºC). Temperature changes generate maximum thermal stress at the cervical region of the enamel. With the highest thermal expansion coefficient, composite resin restorations exhibit higher stress patterns than ceramic and gold restorations.
日常饮食会导致口腔内温度迅速变化。修复牙齿的温度变化引起的热传递和热应力可能会损坏硬组织和软组织成分，导致修复失败。本研究通过三维（3D）有限元分析（FEA）评估了三种间接修复体修复下颌磨牙后的温度分布和相关热应力。
构建了下颌第一磨牙的 3D 有限元模型，包括釉质、牙本质、牙髓、周围骨和 2 类间接牙科金合金、陶瓷和复合树脂修复体。进行瞬态热 FEA 以研究模拟 36°C 至 4°C 或 60°C 温度变化 2 秒后的温度分布和由此产生的热应力。
在两种热条件下，修复模型在 2 秒时具有相似的温度分布。与 60°C 暴露相比，4°C 条件导致更大的热应力值。在 4°C 时，观察到的最高应力值为拉伸应力（56 至 57MPa），而在 60°C 时，观察到的最高应力值为压缩应力（42 至 43MPa）。这些应力出现在舌侧釉质的颈部区域。在两种热条件下，修复表面和树脂水门汀的热应力按以下顺序递减：复合>金>陶瓷。
在修复牙齿中，修复材料的特性不会影响 2 秒时的温度分布。牙髓温度低于活髓组织的阈值（42°C）。温度变化在釉质的颈部区域产生最大的热应力。复合树脂修复体具有最高的热膨胀系数，其表现出比陶瓷和金修复体更高的应力模式。
