Hashemipour Maryam Alsadat, Mohammadpour Ali, Nassab Seiied Abdolreza Gandjalikhan
Kerman Oral and Dental Diseases Research Center, Iran.
Indian J Dent Res. 2010 Apr-Jun;21(2):158-64. doi: 10.4103/0970-9290.66624.
In this paper, the temperature and stress distributions in an exact 3D-model of a restored maxillary second premolar tooth are obtained with finite element approach.
The carious teeth need to restore with appropriate restorative materials. There are too many restorative materials which can be used instead of tooth structures; since tooth structures are being replaced, the restorative materials should be similar to original structure as could as possible.
In the present study, a Mesial Occlusal Distal (MOD) type of restoration is chosen and applied to a sound tooth model. Four cases of restoration are investigated: two cases in which base are used under restorative materials and two cases in which base is deleted. The restorative materials are amalgam and composite and glass-inomer is used as a base material. Modeling is done in the solid works ambient by means of an exact measuring of a typical human tooth dimensions. Tooth behavior under thermal load due to consuming hot liquids is analyzed by means of a three dimensional finite element method using ANSYS software. The highest values of tensile and compressive stresses are compared with tensile and compressive strength of the tooth and restorative materials and the value of shear stress on the tooth and restoration junctions is compared with the bond strength. Also, sound tooth under the same thermal load is analyzed and the results are compared with those obtained for restored models.
Temperature and stress distributions in the tooth are calculated for each case, with a special consideration in the vicinity of pulp and restoration region. Numerical results show that in two cases with amalgam, using the base material (Glass-ionomer) under the restorative material causes to decrease the maximum temperature in the restorative teeth. In the stress analysis, it is seen that the principal stress has its maximum values in composite restorations.
The maximum temperatures are found in the restoration case of amalgam without base. Besides, it is found that restoration has not any influence on the stress values at DEJ, such that for all cases, these values are close to sound tooth results.
本文采用有限元方法获取上颌第二前磨牙修复体精确三维模型中的温度和应力分布。
龋坏牙齿需要用合适的修复材料进行修复。有太多修复材料可用于替代牙齿结构；由于牙齿结构被替换，修复材料应尽可能与原始结构相似。
在本研究中，选择近中咬合远中（MOD）型修复并应用于健康牙齿模型。研究了四种修复情况：两种在修复材料下使用基底的情况和两种不使用基底的情况。修复材料为汞合金和复合树脂，玻璃离子水门汀用作基底材料。通过精确测量典型人类牙齿尺寸在SolidWorks环境中进行建模。使用ANSYS软件通过三维有限元方法分析因饮用热液体而产生的热负荷下牙齿的行为。将拉伸和压缩应力的最高值与牙齿和修复材料的拉伸和压缩强度进行比较，并将牙齿与修复体交界处的剪应力值与粘结强度进行比较。此外，还分析了相同热负荷下的健康牙齿，并将结果与修复模型的结果进行比较。
计算了每种情况下牙齿中的温度和应力分布，特别考虑了牙髓和修复区域附近的情况。数值结果表明，在两种汞合金修复的情况下，在修复材料下使用基底材料（玻璃离子水门汀）可降低修复后牙齿中的最高温度。在应力分析中，可以看到主应力在复合树脂修复体中具有最大值。
在无基底的汞合金修复情况下发现最高温度。此外，发现修复对牙本质-釉质交界（DEJ）处的应力值没有任何影响，对于所有情况，这些值都接近健康牙齿的结果。
