Abstract：
Previous studies have reported successful clinical outcomes after regenerative endodontic procedures (REPs) for immature permanent teeth with pulpal infection. However, it remains unclear whether the procedures promote true regeneration or repair. This case report describes the histologic and electron microscopic characteristics of a human immature permanent premolar with a chronic apical abscess that was treated with an REP. Tooth #20 of a 9-year-old girl underwent an REP. At the 6-year follow-up, the patient was asymptomatic, and closure of the apex and thickening of the dentinal walls were observed. However, 16 years after the procedure, apical periodontitis recurred, necessitating apical surgery. The resected root fragments were obtained during the surgery and analyzed using micro-computed tomography, light microscopy, and scanning electron microscopy. Distinct dentinal tubules and interglobular dentin were observed in the regenerated hard tissue. Cementum-like tissue and a root canal were also observed in the apical fragment. The regenerated root tissue in this case exhibited a structure similar to the native root structure. Therefore, we believe that cell-free REPs possess regenerative potential for teeth diagnosed with pulp necrosis and chronic apical abscess.
摘要：
先前的研究已经报道了再生牙髓手术（REPs）治疗牙髓感染的未成熟恒牙后的成功临床结果。然而,目前尚不清楚该程序是否促进真正的再生或修复。此病例报告描述了用REP治疗的人类未成熟永久前磨牙伴慢性根尖脓肿的组织学和电子显微镜特征。一个9岁女孩的20号牙齿接受了REP。在6年的随访中，病人无症状,并观察到根尖的闭合和牙质壁的增厚。然而,手术16年后，根尖周炎复发，需要根尖手术。手术期间获得切除的根碎片，并使用显微计算机断层扫描进行分析，光学显微镜,和扫描电子显微镜。在再生的硬组织中观察到明显的牙本质小管和球间牙本质。在根尖碎片中还观察到了牙骨质样组织和根管。在这种情况下，再生的根组织表现出与天然根结构相似的结构。因此,我们认为无细胞REP对诊断为牙髓坏死和慢性根尖脓肿的牙齿具有再生潜能.
