牙根纵裂患者的咬合应力分析

Occlusal contact force and stress analysis of molars with vertical root split

目的 研究牙根纵裂致病的咬合力因素。方法 用光法分析 34例患者 39颗患牙的接触合力分布 ,用三维有限元法分析下颌第一恒磨牙在 11种受力状况下的内应力分布。结果 2 6例患者 (31颗患牙 )全口牙齿接触合力分布不均 ,患牙接触合力最大 ;下第一恒磨牙受到咬合力与牙长轴方向呈 30° ,水平力与偏纵向力时 ,近中根根尖部根管壁出现了较大的拉应力且集中于其颊舌中线部位。结论 接受较大咬合力和有害应力并长期集中在患牙近中根根管壁的颊舌中线部位 。

Objective To study the induction of vertical root split by occlusal force. Methods 1. The occlusal contact force was studied in 34 cases (39 teeth) by photocclusion. 2. The stress analysis for the first mandicular molar was studied by three dimensional definite element. Results 1. The occlusal contact force didn't distribute balancedly in 26 cases (31 teeth) and the suffering teeth bore greater force. 2. The bucco lingual central line of the mesial root canal wall underwent greater tensile stress when tooth bore load with 30° angle to axis, or buccal lingual lateral load or logitudinal occlusive load on the masial or distal cusp. Conclusion The vertical root split of molar is associated with greater occlusal force and the stress that concentrated on the buccolingual central line of the mesial root wall for a long time.