Department of Orthodontics, Faculty of Dentistry, Ankara University, Ankara, Turkey.
Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Lokman Hekim University, Ankara, Turkey.
Acta Odontol Scand. 2024 Oct 9;83:582-587. doi: 10.2340/aos.v83.42076.
Third molars (M3) remaining impacted in Class II malocclusion characterised with sagittal mandibular deficiency is a high probability. The null hypothesis of this study is that mesioangular M3s changes position through the eruption way in Class II malocclusion treatment requiring moderate anchorage with four first premolars extraction. The aim of this study is to reconsider the decision to surgically extract impacted third molars in four premolars extraction treatment of Class II malocclusion.
The materials consisted of the pre-treatment and post-treatment lateral cephalograms and orthopantomographs of 30 individuals with skeletal and dental Class II malocclusion with a mean chronological age of 13.48 years, who were treated by the same clinician (H.G.) with four first premolar extractions via the straight wire technique at the Ankara University Faculty of Dentistry Department of Orthodontics, Ankara, Turkey. The sagittal position of the upper and lower incisors and molars, M3 position and M3 space were evaluated with the paired-t test; the relationship between the sagittal position of the upper and lower incisors and molars and the change in M3 position were evaluated with correlation analysis. Results: The study found the retroclination and mesial movement of the upper incisors and molars, and an increase in the M3 space by the fixed orthodontic treatment. An insignificant steepening of both the upper right M3 position and the lower right M3 position was found. A statistically significant increase in the lower right and left side M3 spaces was found. Positive correlations between lower right M3 angulation and the sagittal position of the lower incisors and first molars were found.
Improvement in the mesioangulation of the M3s and an increase in the M3 space were achieved in this study. Based on the findings, it is useful to review the decision for prophylactic surgical extraction of the M3s before orthodontic treatment in such cases, taking into account the risks of postoperative complications.
在伴有下颌骨矢状向不足的 II 类错颌中，第三磨牙（M3）未完全萌出的概率较高。本研究的零假设是，在需要中度支抗的四前磨牙拔除的 II 类错颌治疗中，近中倾斜的 M3 会通过萌出方式改变位置。本研究旨在重新考虑在四前磨牙拔除治疗 II 类错颌中预防性外科拔除阻生第三磨牙的决定。
本研究的材料包括 30 名骨骼和牙齿均为 II 类错颌的个体的治疗前和治疗后侧位头颅侧位片和全景片，平均年龄为 13.48 岁，均由同一位医生（H.G.）使用直丝弓技术在土耳其安卡拉大学牙科学院正畸科进行四前磨牙拔除治疗。使用配对 t 检验评估上颌和下颌切牙和磨牙的矢状位置、M3 位置和 M3 间隙；使用相关分析评估上颌和下颌切牙和磨牙的矢状位置与 M3 位置变化之间的关系。结果：研究发现，固定正畸治疗导致上颌切牙和磨牙的后倾和近中移动，以及 M3 间隙增加。还发现右上颌 M3 位置和右下颌 M3 位置的斜率增加不明显。发现右下颌和左侧 M3 间隙有统计学意义的增加。发现右下颌 M3 角度与下颌切牙和第一磨牙的矢状位置呈正相关。结论：本研究中，M3 的近中倾斜得到改善，M3 间隙增加。根据这些发现，考虑到术后并发症的风险，在这种情况下，在正畸治疗前重新考虑预防性外科拔除 M3 的决定是有用的。
