改良牙冠延长术后组织愈合的动物实验研究

目的: 明确改良牙冠延长术后的组织愈合方式, 为改良牙冠延长术的临床推广应用提供生物学基础。方法: 对5只比格犬的右上中切牙、左上中切牙和左上第一侧切牙分别进行翻瓣术、常规牙冠延长术和改良牙冠延长术, 右上第一侧切牙为对照牙, 不进行手术, 术后36周获取标本进行组织学观察。结果: 颊舌向软硬组织切片苏木素-伊红(hematoxylin-eosin, HE)染色发现翻瓣术的愈合方式为再附着, 与对照组一致。常规牙冠延长术组5只比格犬的根面均存在薄片状的牙骨质缺损, 其中4只比格犬的组织愈合为新附着, 表现为牙骨质缺损区内有新牙骨质形成, 胶原纤维呈一定角度插入其中; 另1只比格犬的组织愈合方式为长结合上皮愈合, 表现为长结合上皮根向移位止于牙骨质缺损区的根方水平。改良牙冠延长术组中4只比格犬根面存在牙骨质缺损(薄片状和浅台阶样缺损各2只), 其中3只比格犬的组织愈合为新附着, 但胶原纤维与根面平行, 1只比格犬的愈合方式为长结合上皮愈合; 另外1只比格犬因组织块未能完整分切而无法观察组织愈合方式。结论: 改良牙冠延长术后的组织愈合方式与常规法相似, 包括新附着和长结合上皮愈合两种方式, 根面处理(根面平整或根面改形)以及根面缺损的类型(薄片状或浅台阶样牙骨质缺损)并未影响组织的愈合方式。

Healing of the dento-gingival junction following modified crown lengthening procedure in beagle dogs

Objective: To evaluate the type of wound healing following modified crown lengthening surgery in dog model to provide a biological basis for its clinical application. Methods: Flap surgery, traditional crown lengthening procedure and modified crown lengthening procedure were performed on the right maxillary central incisor, the left maxillary central incisor and the left maxillary first lateral incisor respectively of five male beagle dogs. The right maxillary first lateral incisors with no surgical intervention were used as controls. Thirty-six weeks after the experimental procedure, tissue blocks were harvested and prepared for histological examination and analysis. Results: Histometric examination of buccolingual sections stained with hematoxylin-eosin demonstrated that the type of wound healing in the flap surgery group was re-attachment, similar to the control group. For the traditional crown lengthening surgery group, all of the five beagle dogs had lamellar cementum defects on root surface, the wound healing of four beagle dogs was new attachment accompanied by new cementum formation at cementum defect areas and the suprac-restal connective tissue was functionally oriented perpendicular to the new cementum. The wound healing of the other beagle dog was long junctional epithelial attachment, in which the junctional epithelium extended to the apical terminus of the cementum defect. In the modified crown lengthening surgery group, four beagle dogs had cementum defects on root surface (two lamellar cementum defects and two shallow platform-like cementum defects), the wound healing of three beagle dogs was new attachment, however, the supracrestal connective tissue was parallel to the root surface. The type of wound healing of another one beagle dog was long junctional epithelial attachment. Wound healing of one beagle dog in this group could not be characterized due to incomplete dissection. Conclusion: Wound healing in the modified crown lengthening surgery group was similar to the traditional crown lengthening surgery group, and two types of wound healing were observed: new attachment and long junctional epithelium attachment. Neither type of root treatment procedure (root planing or root reshaping) nor root surface defect pattern (the lamellar cementum defect or shallow platform-like cementum defect) influenced the observed type of wound healing.