| Summary: | 碩士 === 高雄醫學大學 === 牙醫學研究所 === 96 === Abstract
Some reports point out the weakness of endodontically treated teeth, that it would reinforce the teeth by use of posts. However, residual tooth structure has major influence on resistance of tooth fracture. Teeth with proximal caries often need endodontic treatment. In those teeth, there are no tooth structure in mesial or distal side. Study for those situation is rare. The purpose of this study was to analyze the stress of post and core for mandibular first premolar with different mesial proximal decay during normal masticatory load by finite element method (FEM). In this study, the three-dimensional finite element method was employed to analyze the stress difficult to calculate by traditional clinical observation or experimental approaches. Solid models of the mandibular first premolar with five height of mesial tooth structure (2 mm, 1.5 mm, 1.0 mm, 0.5 mm, 0 mm) and casting post was build up. Solid model was transferred to the mesh model in FE package(ANSYS) to process the stress analysis. Five different force all 100 N were applied on buccal cusp tip: (1)PV: vertical force along tooth axis; (2)PB: 45 degree force from buccal to lingual direction. ; (3)PL: 45 degree force from lingual to buccal direction. ; (4)PM: 45 degree force from mesial to distal direction. ; (5)PD: 45 degree force from distal to mesial direction. The results showed that there are stress concentration increase in contact area between tooth and post with mesial tooth structure decrease in PV force. We also found that the stress decreased with mesial tooth structure decrease in PB and PL. But when tooth structure not enough of 1 mm, the stress concentrate increase observably. The conclusions of this study were that stress will concentrate in the area between post and tooth structure in PV force. PB and PL have more influence than PM and PDwhen proximal tooth structure loss. Lateral force has more influence on post and tooth structure than vertical force.
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