Objective: To assess the effects of loupes and microscope on the posture of prosthodontists when preparing the laminate veneer, and to assess the clinical value of loupes and microscope from the ergonomic aspects.
Methods: Twenty young prosthodontists from Department of Prosthodontics, Peking University School and Hospital of Stomatology were recruited into this study, which was a prospective, single blind, self-control trials. The research hypothesis was concealed and the participants were deceived about the precise purpose of the study to counterbalance the lack of direct blinding. The prosthodontists prepared laminate veneers of open window type in the artificial dental model, under routine visual field (control group), 2.5× headwear loupes (loupes group), and 8× operating microscope (microscopic group) by turning. The participants were photographed from profile view and front view. Thereafter, the subjective assessment was performed by themselves using the visual analogue score (VAS). The expert assessment was performed by two professors using modified-dental operator posture assessment instrument on the basis of photographs of the profile view and front view.
Results: The subjective assessment scores for the control group, loupes group and microscopic group were 4.55±1.96, 7.90±1.12, and 9.00±0.92, respectively. There was significant difference between the three groups' subjective scores (P < 0.05). The expert assessment scores for the control group, loupes group and microscopic group were 16.38±1.52, 15.15±1.30, and 13.60±0.88, respectively. There was significant difference between the three groups' expert assessment scores (P < 0.05). Specifically, the three groups' expert assessment scores were significantly different (P < 0.05) in trunk position (front to back) (1.33±0.41, 1.03±0.11, 1.00±0.00), head and neck position (front to back) (2.75±0.38, 2.13±0.36, 1.23±0.38), elbows level (1.38±0.43, 1.40±0.45, 1.13±0.22), and shoulders level (1.43±0.41, 1.23±0.34, 1.13±0.28). Thereinto, the microscopic group was better than loupes group in head and neck position (front to back) and elbows level (P < 0.05).
Conclusion: Loupes and microscope improve the posture of the prosthodontist when preparing the laminate veneer, in which the microscope is better than loupes. Therefore, the magnification devices have clinical value from the ergonomic aspects.
目的: 研究放大镜和显微镜对口腔修复医生贴面牙体预备时体位的影响，从人体工程学角度对放大镜和显微镜的临床应用价值进行评价。
方法: 从北京大学口腔医院修复科选择20名口腔修复医生进行前瞻性、单盲、自身对照试验。研究过程中不告知受试者研究的试验假设和真实目的，每人依次在常规视野下(空白对照组)、2.5倍头戴式放大镜下(放大镜组)和8倍医用显微镜下(显微镜组)在仿头模内完成右上中切牙开窗型贴面牙体预备，试验过程中拍摄医生的侧面和正面体位照片。贴面牙体预备完成后，由医生本人利用视觉模拟评分法对自身体位进行主观评分，由两名专家利用侧面和正面体位照片按照“改良口腔医生体位评分表”对医生的体位进行专家评分。
结果: 空白对照组、放大镜组和显微镜组的主观评分分别为4.55±1.96、7.90±1.12、9.00±0.92，三组之间差异有统计学意义(P < 0.05)；专家评分分别为16.38±1.52、15.15±1.30、13.60±0.88，三组之间差异有统计学意义(P < 0.05)。三组的专家评分在躯干前后向位置(1.33±0.41、1.03±0.11、1.00±0.00)、头颈前后向位置(2.75±0.38、2.13±0.36、1.23±0.38)、肘关节位置(1.38±0.43、1.40±0.45、1.13±0.22)和肩部高度(1.43±0.41、1.23±0.34、1.13±0.28)这4项评分上的差异有统计学意义(P < 0.05)，其中，在头颈前后向位置和肘关节位置方面，放大镜组与显微镜组之间的差异有统计学意义(P < 0.05)。
结论: 放大镜和显微镜均能改善口腔修复医生牙体预备时的体位，其中显微镜的效果更好，从人体工程学的角度二者均具有较高的临床应用价值。
Keywords: Dentists; Human engineering; Loupes; Microscopes; Posture.