Evidence for Prosthodontic Intervention to the Shortened Dental Arch (SDA)

目的：在过去的二十年里，缩短牙弓（SDA）的概念已被引入作为后牙缺失患者的治疗策略！即不需要修复缺失的磨牙区域。另一方面，临床经验表明，从咬合不稳定开始的功能障碍的各种可能性。本研究的目的是阐明SDA的概念是否适用于所有的后牙缺失患者。研究选择：10例单侧后牙缺失的患者入组本研究，并对他们的SDA条件进行了多重评价。该评价包括客观评价（TMJ的X线片评价和最大自主咬合时髁突位移的测量）和主观评价（问卷调查）。咬合过程中无牙侧髁突的位移值显著高于有牙侧髁突。40%的受试者表现出高水平的投诉SDA conditions.Conclusions：这些结果表明口腔功能的潜在风险。我们希望提出临床指南，以决定是否“等待和观望”SDA患者没有任何积极的治疗或立即开始修复干预。

Purpose : In the last two decades, the Shortened Dental Arch (SDA) concept has been introduced as a treatment strategy for posterior edentulous patients! i.e. there is no need to restore the missing of molar region. On the other hand, clinical experience suggests various possibilities for functional disturbance starting from instability of occlusion. The purpose of this study is to clarify whether SDA concept fits for all posterior edentulous patients.Study selection : Ten patients with unilaterally posterior tooth missing were enrolled in this study, and a multiple evaluation for SDA condition was applied to them. This evaluation consists of the objective evaluation (radiographic evaluation for TMJ and measurement of condylar displacements during maximum voluntary clenching) and the subjective evaluation (questionnaire).Result : Abnormal radiographic appearances were observed in 50% of subjects. Condylar displacements during clenching were significantly high value in the edentulous-side condyle compared to that in the dentulous-side condyle. 40% of subjects showed high level of complains for SDA conditions.Conclusions : These results indicated the potential risks for the oral functions. We wish to propose the clinical guidelines for making a decision whether to "wait and see" the SDA patients without any positive treatment or to start prosthetic intervention immediately.