目的: 观察成年人后牙失去邻牙合接触后的三维位置变化,从近远中向、颊舌向、牙合龈向以及三维方向的移动幅度和移动速度等方面进行探讨。方法: 选择北京大学口腔医院修复科2019年1月1日至2月28日20例金属桩核修复的病例,进行观察性研究,所修复牙齿在治疗前均存在完整的近中、远中及咬合接触,桩核牙体预备时去除全部邻牙合接触。在桩核修复牙体预备后当日和戴入金属桩核当日,分别使用口内扫描仪获取桩核预备体的三维位置。在软件内测量牙齿在近远中向、颊舌向、牙合龈向的移动幅度,并由此计算牙齿在三维方向的移动幅度,再根据两次扫描的时间间隔计算牙齿的移动速度。结果: 受试者女性和男性各10人,平均年龄为(29.5±4.9)岁,平均观察时间为(10.9±2.7) d。牙齿的平均移动幅度在近远中向为(134.8±61.2) μm、颊舌向为(110.3±39.5) μm、牙合龈向为(104.8±57.5) μm、三维方向为(211.4±71.0) μm。女性的牙齿移动幅度在近远中向、颊舌向和三维方向上显著高于男性(P<0.05)。牙齿的平均移动速度在近远中向为(13.1±7.8) μm/d、颊舌向为(10.6±4.5) μm/d、牙合龈向为(10.1±6.8) μm/d、三维方向为(20.5±9.7) μm/d,女性的牙齿移动速度在近远中向和颊舌向上显著高于男性(P<0.05),在三维方向上女性的牙齿移动速度略高于男性[(24.0±11.2) μm/d vs. (16.9±6.7) μm/d],但二者间差异无统计学意义(P>0.05)。结论: 天然牙在失去邻牙合接触后,其三维位置会发生变化,且女性比男性的牙齿移动幅度更大、速度更快。

Objective: To observe the movement of posterior teeth after losing the interproximal and occlusal contacts in adults from the amount and speed of mesial-distal, buccal-lingual, occlusal-gingival and three-dimensional movements. Methods: Twenty cases of metal post-core restoration from the Department of Prosthodontics, Peking University School and Hospital of Stomatology were recruited into this study, which was an observational study. The restored teeth had complete mesial, distal, and occlusal contacts before treatment. All the interproximal and occlusal contacts were removed during the preparation for the post-core. The three-dimensional positions of the post-core preparation were obtained by the intraoral scanner at the day of tooth preparation and that of post-core placement. The amounts of mesial-distal, buccal-lingual and occlusal-gingival tooth movement were measured in the software. On this basis, the amount of three-dimensional tooth movement was calculated. The speed of tooth movement was calculated based on the elapsed time between the two scans. Results: Ten females and ten males with an average age of (29.5±4.9) years were recruited. The average elapsed time was (10.9±2.7) days. The amount of the mesial-distal tooth movement was (134.8±61.2) μm, of the buccal-lingual tooth movement was (110.3±39.5) μm, of the occlusal-gingival tooth movement was (104.8±57.5) μm, and of the three-dimensional tooth movement was (211.4±71.0) μm, respectively. The amounts of mesial-distal, buccal-lingual and three-dimensional tooth movements were larger in female than in male (P<0.05). The speed of the mesial-distal tooth movement was (13.1±7.8) μm/d, of the buccal-lingual tooth movement was (10.6±4.5) μm/d, of the occlusal-gingival tooth movement was (10.1±6.8) μm/d, and of the three-dimensional tooth movement was (20.5±9.7) μm/d, respectively. The speed of mesial-distal and buccal-lingual tooth movements were larger in female than in male (P<0.05). The speed of three-dimensional tooth movement was slightly larger in female than in male, while there was no significant difference between different genders (P>0.05). Conclusion: The three-dimensional position of posterior teeth changed after losing the interproximal and occlusal contacts in adults. The female had more significant and faster tooth movement than the male.