Cho Sin-Yeon, Kim Euiseong
Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, Yonsei University College of Dentistry, Seoul, Korea.
Restor Dent Endod. 2013 May;38(2):59-64. doi: 10.5395/rde.2013.38.2.59. Epub 2013 May 28.
Apical surgery cuts off the apical root and the crown-to-root ratio becomes unfavorable. Crown-to-root ratio has been applied to periodontally compromised teeth. Apical root resection is a different matter from periodontal bone loss. The purpose of this paper is to review the validity of crown-to-root ratio in the apically resected teeth. Most roots have conical shape and the root surface area of coronal part is wider than apical part of the same length. Therefore loss of alveolar bone support from apical resection is much less than its linear length.The maximum stress from mastication concentrates on the cervical area and the minimum stress was found on the apical 1/3 area. Therefore apical root resection is not so harmful as periodontal bone loss. Osteotomy for apical resection reduces longitudinal width of the buccal bone and increases the risk of endo-perio communication which leads to failure. Endodontic microsurgery is able to realize 0 degree or shallow bevel and precise length of root resection, and minimize the longitudinal width of osteotomy. The crown-to-root ratio is not valid in evaluating the prosthodontic prognosis of the apically resected teeth. Accurate execution of endodontic microsurgery to preserve the buccal bone is essential to avoid endo-perio communication.
根尖手术会切除根尖部分，导致冠根比变得不理想。冠根比已应用于牙周受损的牙齿。根尖切除术与牙周骨丧失是不同的情况。本文的目的是回顾冠根比在根尖切除术后牙齿中的有效性。大多数牙根呈圆锥形，相同长度的冠部牙根表面积比根尖部宽。因此，根尖切除导致的牙槽骨支持丧失远小于其线性长度。咀嚼产生的最大应力集中在颈部区域，而最小应力出现在根尖1/3区域。因此，根尖切除术不像牙周骨丧失那样有害。根尖切除的截骨术会减小颊侧骨的纵向宽度，并增加牙髓-牙周相通的风险，从而导致治疗失败。牙髓显微外科手术能够实现0度或浅斜面以及精确的牙根切除长度，并将截骨术的纵向宽度降至最低。冠根比在评估根尖切除术后牙齿的修复预后方面并不有效。准确实施牙髓显微外科手术以保留颊侧骨对于避免牙髓-牙周相通至关重要。
