下颌牙列缺失固定种植修复的(牙合)学研究

目的 探讨下颌牙列缺失固定种植修复的咬合及肌电特点,为无牙颌固定种植修复的治疗提供参考。方法 选取60例下颌牙列缺失固定种植修复的患者,其中A组上颌为固定种植修复,B组上颌为天然牙列,C组上颌为可摘局部义齿,每组20例患者。使用T-scan记录4种颌位的咬合特点,采用肌电仪记录静息状态及牙尖交错位最大紧咬时颞肌前束和咬肌的电位变化,探讨咬合与肌电之间的联系。结果 咬合分析结果：C组的咬合接触时间、最大咬合力时左右侧咬合力平衡度及咬合力中心左右向偏移度、咬合力中心位移、前伸颌及侧方颌的咬合分离时间均大于A、B两组（P<0.05）,3组最大咬合力时咬合力中心前后向偏移度及前牙区咬合力百分比的差异均无统计学意义（P>0.05）。肌电分析结果：C组的静息状态下肌电幅值、牙尖交错位最大紧咬时咀嚼肌不对称指数大于A、B两组（P<0.05）,A、B组的牙尖交错位最大紧咬时肌电幅值大于C组（P<0.05）。结论 在下颌牙列缺失固定种植修复中,当上颌为可摘局部义齿时,咬合不稳定程度及咬合力中心偏移大于上颌为固定种植修复和天然牙列的患者。咬合与肌电息息相关,上颌可摘局部义齿可造成肌电活动增加,降低咀嚼肌的潜力,双侧肌电的不对称与咬合不平衡有关。

Gnathology in implant-supported fixed restoration in edentulous mandible

Objective This study aims to investigate the occlusal and myoelectric characteristics of implant-supported fixed denture in the mandibular region and provide reference for the design of fixed restoration. Methods Sixty edentulous patients with implant-supported fixed denture were selected and divided into three groups: group A, 20 cases with implant-supported fixed restoration in the maxillary region; group B, 20 cases with natural dentition, and group C, 20 cases with removable partial denture. The T-scan 8.0 digital occlusion analysis system was used to evaluate the occlusal characteristics of patients in the three groups at intercuspal, protrusion, and left and right lateral positions. Electromyography was used to analyze the myoelectric amplitude and bilateral asymmetry index of the anterior temporalis and masseter of the three groups in different states such as resting and clenching. The relationship between occlusion and myoelectricity was also investigated. Results In the occlusion analysis by T-scan, the occlusion time, the balance of left and right bite force, the left and right asymmetry of the occlusion center, the trajectory of central occlusion force, and the disclusion time were higher in group C than in groups A and B (P<0.05). No significant differences were observed in the anterior and posterior asymmetry of the occlusion center and percentage of bite force at anterior region among the three groups. In the analysis of myoelectricity, the myoelectric amplitude at resting state and the asymmetry index of masticatory muscles in group C were higher than those in groups A and B (P<0.05). The myoelectric amplitude during clenching in groups A and B groups was higher than that in group C (P<0.05). Conclusion In implant-supported fixed restoration at edentulous mandibular, when maxillary includes the removable partial denture, degree of occlusal instability and left and right asymmetry of occlusion center are greater than those with the natural dentition and implant-supported fixed denture at maxillary. The myoelectricity is closely related to occlusion. The removable partial denture can increase the myoelectric activity and reduce the potential of the masticatory muscle. The asymmetry of bilateral myoelectricity is related to the occlusion imbalance.