부산대학교 도서관

Purpose: This study investigated the influence of intensity of occlusal contact, or occlusal height of an implant-retained single restoration on the stress in the crown surface and supporting bone.Methods: A two-dimensional finite element model of the maxillary and mandibular first molars with supporting periodontal structures was created (Model M-M). One of the molars was replaced by a restoration retained by a thread-type implant to produce Model I-M (implant in maxilla) and Model M-I (implant in mandible). The models were isotropic and linearly elastic, except for the periodontal ligament with a non-linear material property to simulate the tooth movements. The tooth-to-tooth contact under the bite force was simulated by the vertical displacement of the mandible up to 0.24 mm from the initial occlusal contact. Non-linear contact analysis was conducted to calculate the stress in both the restoration and the supporting tissues.Results: To obtain a restoration that shows the same stress in the occlusal surface as that in the natural molars under the maximum bite force, the occlusal heights in Models I-M and M-I were to be reduced by 0.10 mm and 0.11 mm, respectively. The restorations were not expected to occlude with their natural molar antagonists under bite force lower than 13.0% and 15.8% of the maximum force, respectively.Conclusion: Reduction in the intensity of the occlusal contact, or decreased occlusal height of an implantretained single restoration, allows the establishment of an equivalent occlusal stress with the natural molars under the maximum bite force. This adjustment, either during fabrication or try-in procedure, can suppress excessive stress that may be created in the tissues. With this procedure, however, the restoration does not contact the antagonistic tooth under a relatively low bite force.