Nordlander J, Weir D, Stoffer W, Ochi S
Veterans Administration Medical Center, San Francisco, Calif.
J Prosthet Dent. 1988 Aug;60(2):148-51. doi: 10.1016/0022-3913(88)90304-6.
Convergence angles of full-coverage preparations were measured in a clinical environment and compared with each other and the ideal taper of 4 to 10 degrees. Despite educational emphasis, the practical application of preparation design routinely exceeds the ideal taper and casts a different light on retention and resistance characteristics described in both laboratory and theoretical work. Comparison of preparations done by residents and by prosthodontists in this study showed that ideal preparation taper is seldom achieved. Given the complex interrelationships of clinical, theoretical, and mechanical factors that determine the retention and resistance characteristics of a preparation in vivo, it is advisable to design preparations that blend retentive characteristics with functional demands. Because it is difficult to assess preparation taper intraorally, efforts should be directed to using other retentive devices, especially on posterior preparations where ideal taper is difficult to achieve.
在临床环境中测量全冠修复体预备体的聚合角度，并相互比较，同时与4至10度的理想锥度进行比较。尽管在教育中强调了理想锥度，但预备体设计的实际应用通常超过了理想锥度，这对实验室和理论研究中描述的固位和抗力特性提出了不同的看法。本研究中对住院医师和修复专科医师所做的预备体进行比较，结果显示很少能达到理想的预备体锥度。鉴于决定体内预备体固位和抗力特性的临床、理论和机械因素之间存在复杂的相互关系，建议设计出将固位特性与功能需求相结合的预备体。由于在口腔内难以评估预备体锥度，应致力于使用其他固位装置，尤其是在难以达到理想锥度的后牙预备体上。
