Andreasen J O, Paulsen H U, Yu Z, Bayer T
Department of Oral Surgery and Oral Medicine, University Hospital (Rigshospitalet), Copenhagen, Denmark.
Eur J Orthod. 1990 Feb;12(1):38-50. doi: 10.1093/ejo/12.1.38.
The purpose of the present study was to analyse the extent of root development subsequent to transplantation in a material of 370 transplanted premolars. Before transplantation, the grafts were classified according to stage of root development (i.e. quarters of root length and constriction of the apical foramen) and length of tooth development (measured in mm from the cusp tip to the apical foramen). At radiographic controls the extent of root formation was registered. These figures were compared to the final tooth length of 288 non-transplanted premolars from the present material as well as to tooth length determinations of 534 premolars extracted for orthodontic purposes. Furthermore, intra-individual and inter-individual differences in tooth length were examined in a skull material with 40 pairs of premolars. These method studies indicated that root growth was probably determined genetically with great right-left accuracy and variation related to location of premolar (maxilla or mandible) and sex. A statistical analysis of the transplant material revealed that stage as well as length of tooth development assessed prior to transplantation were significantly related to final tooth length after transplantation. In most cases of transplantation performed at early stages of root development, a reduction in the final root length was seen. When a qualitative analysis of root development was performed in teeth with incomplete root formation at the time of transplantation, and where a homologous non-transplanted premolar was present, it was found that 14 per cent showed total arrest of root formation, 65 per cent partial arrest whereas 21 per cent showed no arrest (i.e. normal root formation). Premolars in ectopic position in the mandible before transplantation showed a significantly reduced root growth compared to matched pairs with normal position of the tooth graft. The present study indicated that no, partial or total damage to the Hertwig's epithelial root sheath was probably the explanatory factor for variations in root growth.
本研究的目的是分析370颗移植前磨牙材料移植后牙根发育的程度。移植前，根据牙根发育阶段（即牙根长度的四分之一和根尖孔的缩窄情况）和牙齿发育长度（从牙尖到根尖孔的毫米数）对移植物进行分类。在影像学检查时记录牙根形成的程度。将这些数据与本材料中288颗未移植前磨牙的最终牙长以及534颗因正畸目的拔除的前磨牙的牙长测定结果进行比较。此外，在一个有40对前磨牙的颅骨材料中检查了牙长的个体内和个体间差异。这些方法研究表明，牙根生长可能由基因决定，左右精度很高，且变异与前磨牙的位置（上颌或下颌）和性别有关。对移植材料的统计分析表明，移植前评估的牙根发育阶段和长度与移植后的最终牙长显著相关。在牙根发育早期进行的大多数移植病例中，最终牙根长度会缩短。当对移植时牙根形成不完全且存在同源未移植前磨牙的牙齿进行牙根发育的定性分析时，发现14%的牙齿牙根形成完全停止，65%的牙齿牙根部分停止发育，而21%的牙齿牙根没有停止发育（即正常牙根形成）。移植前在下颌异位的前磨牙与牙齿移植位置正常的匹配对相比，牙根生长显著减少。本研究表明，赫特维希上皮根鞘无损伤、部分损伤或完全损伤可能是牙根生长变异的解释因素。
