Department of Oral Health Sciences-Orthodontics, KU Leuven and Dentistry, University Hospitals Leuven, Leuven, Belgium.
OMFS IMPATH, Department of Imaging & Pathology, Faculty of Medicine, University Leuven & Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium.
J Dent. 2017 Jun;61:55-66. doi: 10.1016/j.jdent.2017.03.007. Epub 2017 Mar 27.
To analyse the effect of first and second premolar extractions on eruption space for upper and lower third molars and on third molar position and angulation during orthodontic treatment.
The sample consisted of 296 patients of which 218 patients were orthodontically treated without extraction and 78 patients with extraction of first or second premolars. The eruption space for third molars was measured on pre- and posttreatment lateral cephalograms, whereas the angulation, vertical position, the relation with the mandibular canal and the mineralization status of third molars were evaluated using pre- and posttreatment panoramic radiographs. All data were statistically analyzed.
The increase in eruption space and the change in vertical position of upper and lower third molars significantly differed between patients treated with and without premolar extractions, whereas the change in angulation, relationship with the mandibular canal and mineralization status of the third molars did not significantly differ between patients treated with and without premolar extractions.
The retromolar space and the position of third molars significantly change during orthodontic treatment in growing patients. Premolar extractions have a positive influence on the eruption space and vertical position of third molars, whereas they do not influence the angular changes of third molars. Due to the retrospective character of the study, these conclusions should be carefully considered. Further prospective research is necessary for better insights into this complex topic.
This study stresses the importance of considering the possible effects of orthodontic treatment on third molars during treatment planning.
分析第一和第二前磨牙拔除对上、下颌第三磨牙萌出间隙以及正畸治疗中第三磨牙位置和角度的影响。
样本包括 296 名患者，其中 218 名患者接受非拔牙正畸治疗，78 名患者接受第一或第二前磨牙拔除。第三磨牙萌出间隙在治疗前后的侧位头颅侧位片上进行测量，而第三磨牙的角度、垂直位置、与下颌管的关系以及矿化状态则通过治疗前后的全景片进行评估。所有数据均进行统计学分析。
接受和不接受前磨牙拔除的患者之间，第三磨牙萌出间隙的增加和上下第三磨牙垂直位置的变化存在显著差异，而第三磨牙角度、与下颌管的关系以及矿化状态的变化在接受和不接受前磨牙拔除的患者之间无显著差异。
在生长中的患者中，磨牙后间隙和第三磨牙的位置在正畸治疗期间会发生显著变化。前磨牙拔除对上、下颌第三磨牙的萌出间隙和垂直位置有积极影响，而对第三磨牙的角度变化没有影响。由于研究的回顾性特征，这些结论应谨慎考虑。进一步的前瞻性研究对于更好地了解这一复杂问题是必要的。
本研究强调了在治疗计划中考虑正畸治疗对第三磨牙可能产生的影响的重要性。
