The clinical meaning of external cervical resorption in maxillary canine: transoperative dental trauma

External Cervical Resorption in maxillary canines with pulp vitality is frequently associated with dental trauma resulting from surgical procedures carried out to prepare the teeth for further orthodontic traction. Preparation procedures might surgically manipulate the cementoenamel junction or cause luxation of teeth due to applying excessive force or movement tests beyond the tolerance limits of periodontal ligament and cervical tissue structures. Dentin exposure at the cementoenamel junction triggers External Cervical Resorption as a result of inflammation followed by antigen recognition of dentin proteins. External Cervical Resorption is painless, does not induce pulpitis and develops slowly. The lesion is generally associated with and covered by gingival soft tissues which disguise normal clinical aspects, thereby leading to late diagnosis when the process is near pulp threshold. Endodontic treatment is recommended only if surgical procedures are rendered necessary in the pulp space; otherwise, External Cervical Resorption should be treated by conservative means: protecting the dental pulp and restoring function and esthetics of teeth whose pulp will remain in normal conditions. Unfortunately, there is a lack of well-grounded research evincing how often External Cervical Resorption associated with canines subjected to orthodontic traction occurs.

伴牙髓活力的上颌尖牙外颈部吸收（External Cervical Resorption）常与为开展后续正畸牵引而进行的牙体预备外科操作所致的牙外伤相关。牙体预备过程中，术者可能会对釉牙骨质界（cementoenamel junction）进行外科操作，或因施加过大外力、超出牙周膜及颈部组织结构耐受限度的移动测试，造成牙脱位。釉牙骨质界处的牙本质暴露会引发炎症反应，进而通过牙本质蛋白的抗原识别过程诱发外颈部吸收。外颈部吸收无疼痛感，不会引发牙髓炎，且进展缓慢。该病变通常被牙龈软组织覆盖，掩盖了正常的临床体征，因此当病变进展接近牙髓腔时才会被晚期诊断。仅当牙髓腔需实施必要的外科手术操作时，方推荐牙髓治疗；反之，牙髓状态正常的患牙伴发外颈部吸收时，应采用保守治疗方案：保护牙髓，恢复患牙的功能与美观性。遗憾的是，目前尚无充分可靠的研究明确接受正畸牵引的尖牙伴发外颈部吸收的发生率。