Photoelastic stress analysis of four kinds of prosthodontia design for mandibular molar with hemisection

AIM:To investigate the stress distribution of alveolar bone caused by four kinds of fixed prosthesis design for first mandibular molar after hemisection. METHODS:The photoelastic model of normal mandibular first molar in D area was selected as the control group. Photoelastic stress freeze sectioning analysis was employed to investigate the stress distribution around the reserved distal root of the first mandibular molar with four kinds of fixed prosthesis designs. After the hemisection,the restorations of combined crowns of the second mandibular premolar,the first and second mandibular molars,combined crowns of the second mandibular premolar and first mandibular molar com-bined crowns of the first and second mandibular molars and single crown of the first mandibular molar were designed. RESULTS:The stress peak value of the combined crowns of the second mandibular premolar and first mandibular molar was nearly equal to that of the combined crowns of the second mandibular premolar,the first and second mandibular molars and it was slightly larger than that of the control group. The stress peak value of the combined crowns of the first and second mandibular molars was twice of the control group,while in the models of the single crown,the value was over 3 times of the control group. CONCLUSIONS:The restoration of the combined crown of the second mandibular premolar and first mandibular molar,is well as the combined crown of the second mandibular premolar,the first and second mandibular molars are more applicable for the reserved root following the hemisection therapy.