Tsolakis A I, Spyropoulos M N, Katsavrias E, Alexandridis K
Department of Orthodontics University of Athens, Greece.
Eur J Orthod. 1997 Feb;19(1):9-19. doi: 10.1093/ejo/19.1.9.
The purpose of this study was to investigate the effect of protruded mandibular function on bilaterally condylectomized mandibles of growing rats. Sixty 4-week-old rats were divided into three experimental and two control groups each consisting of 12 animals as follows: (A) bilateral condylectomy was performed and the mandible was left to function normally; (B) the mandible was protracted forward without any condylectomy; (C) after bilateral condylectomy, the mandible was forced to function in a protruded position; (D) the animals were used as controls without any operation or appliance; and (E) a sham operation was performed in the condylar area but no appliance was used. Mandibular protraction was achieved by means of a specific appliance acting via rubber bands pulling the mandible in a straight, forward direction with a force of 25 g for 12 hours/day. The experimental period was 30 days. Lateral and dorsoventral radiographs were taken and vital dyes were administered on days 1 and 30 for all animals. Cephalometric analysis included 10 measurements. Findings resulting from statistical analysis of measurements in the five groups are summarized as follows: (i) between group A and groups D and E, less growth was found in group A; (ii) between group B and groups D and E, more growth was found in group B; (iii) between group A and group B, more growth was found in group B; (iv) between group A and group C, more growth was found in group C; and (v) between group B and group C, more growth was found in group B. These findings support the conclusion that although mandibular propulsion enhances growth even after condylectomy, the condyle seems to be an essential element for normal growth and development.
本研究的目的是探讨下颌前伸功能对生长发育期大鼠双侧髁突切除术后下颌骨的影响。将60只4周龄大鼠分为3个实验组和2个对照组，每组12只动物，分组如下：(A) 进行双侧髁突切除术，下颌骨正常行使功能；(B) 未进行任何髁突切除术，下颌骨向前牵引；(C) 双侧髁突切除术后，下颌骨被迫处于前伸位行使功能；(D) 动物作为对照组，未进行任何手术或佩戴矫治器；(E) 在髁突区域进行假手术，但未使用矫治器。通过一种特殊的矫治器实现下颌骨的前伸，该矫治器通过橡皮筋以25 g的力将下颌骨沿直线向前牵引，每天牵引12小时。实验期为30天。在第1天和第30天对所有动物拍摄侧位和背腹位X线片，并注射活性染料。头影测量分析包括10项测量指标。对五组测量结果进行统计分析得出的结果总结如下：(i) A组与D组和E组相比，A组生长较少；(ii) B组与D组和E组相比，B组生长较多；(iii) A组与B组相比，B组生长较多；(iv) A组与C组相比，C组生长较多；(v) B组与C组相比，B组生长较多。这些结果支持以下结论：虽然即使在髁突切除术后下颌前伸也能促进生长，但髁突似乎是正常生长发育的一个重要因素。
