Department of Orthodontics and Dentofacial Orthopedics, Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India, Phone: +91 8872362240, e-mail:
Department of Orthodontics and Dentofacial Orthopedics, Dr Harvansh Singh Judge Institute of Dental Sciences and Hospital, Panjab University, Chandigarh, India.
J Contemp Dent Pract. 2020 Oct 1;21(10):1182-1188.
The study aimed to compare the prospective changes in mandibular third molar angulation in high anchorage cases treated with first premolar extractions vs non-extraction orthodontic treatment.
The sample consisted of 56 nongrowing patients: Group I had 26 patients with a high anchorage requirement who underwent first premolar extractions and group II had 30 patients who underwent non-extraction treatment. Pretreatment, mid-treatment, and posttreatment panoramic radiographs were obtained for group I and pretreatment and posttreatment for group II. Angle between M2 (second molar)-horizontal reference plane (HRP), M3 (third molar)-HRP, and M2-M3 were measured bilaterally. Data were analyzed using Student test and ANOVA test ( value < 0.05).
Statistically significant increase was found between the pretreatment, mid-treatment, and posttreatment values of M2-M3 in group I ( value = 0.02 R and value = 0.049 L) and between pretreatment to posttreatment values of M2-HRP in group II bilaterally ( value = 0.001). Significant increase was found in the M2-M3 angulations in group II on the right side ( value = 0.036). M3-HRP decreased in group I without reaching statistical significance. No statistically significant intergroup differences were found between the two groups in relation to M2-HRP, M3-HRP, and M2-M3 angulations.
M2-M3 angulations increased significantly bilaterally in group I and on the right side in group II, indicating worsening of third molar angulation. M3-HRP worsened in group I without reaching statistical significance. Extraction therapy in high anchorage cases does not lead to an improvement in third molar angulation.
The extraction of first premolars in high anchorage cases does not lead to an improvement in the angulation of mandibular third molars; moreover, the angulation worsened with extraction therapy. Prospective orthodontic patients need to be cautioned against any improvement in mesioangular impaction of mandibular third molars in high anchorage premolar extraction cases.
本研究旨在比较高支抗病例中，经第一前磨牙拔牙和非拔牙正畸治疗后下颌第三磨牙角度的前瞻性变化。
该样本包括 56 名非生长患者：第 I 组 26 例患者需要高支抗，行第一前磨牙拔牙；第 II 组 30 例患者行非拔牙治疗。第 I 组获得治疗前、治疗中期和治疗后全景片，第 II 组获得治疗前和治疗后全景片。双侧测量 M2（第二磨牙）-水平参考平面（HRP）、M3（第三磨牙）-HRP 之间的角度以及 M2-M3。使用学生 t 检验和方差分析（ 值 < 0.05）进行数据分析。
第 I 组 M2-M3 在治疗前、治疗中期和治疗后之间的数值有统计学显著增加（ 值=0.02 R 和 值=0.049 L），第 II 组双侧 M2-HRP 在治疗前至治疗后之间的数值有统计学显著增加（ 值=0.001）。第 II 组右侧 M2-M3 角度显著增加（ 值=0.036）。第 I 组 M3-HRP 减少，但无统计学意义。两组间 M2-HRP、M3-HRP 和 M2-M3 角度无统计学显著差异。
第 I 组双侧和第 II 组右侧 M2-M3 角度显著增加，表明第三磨牙角度恶化。第 I 组 M3-HRP 恶化，但无统计学意义。高支抗病例中第一前磨牙的拔除并不能改善第三磨牙的角度。
高支抗病例中第一前磨牙的拔除并不能改善下颌第三磨牙的角度；此外，拔牙治疗会使角度恶化。需要告诫有前瞻性正畸治疗需求的患者，在高支抗前磨牙拔牙病例中，下颌第三磨牙近中阻生的角度不会有所改善。
