Prasanna Arvind T R, Ramasamy N, Subramanian A K, Selvaraj A, Siva S
Department of Orthodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Chennai, India.
Department of Orthodontics, SRM Dental College, SRM University, Chennai, India.
Orthod Craniofac Res. 2024 Apr;27(2):211-219. doi: 10.1111/ocr.12704. Epub 2023 Aug 8.
Root resorption in orthodontics is associated with direction and magnitude of force application as primary etiological factors. Well-controlled trials that utilize three-dimensional segmentation to detect volumetric changes in tooth structure are required to assess the quantitative nature of root resorption.
To assess the severity of root resorption (RR) during retraction of maxillary anteriors with three different force vectors (with and without skeletal anchorage) via cone-beam computed tomography (CBCT) superimpositions.
Three-arm parallel randomized clinical trial (RCT).
Forty-two (16 males, 26 females) patients, (17-28 years), in permanent dentition with bimaxillary protrusion were randomly allocated to three groups of 14 patients each using block randomization (1:1:1 ratio) and allocation concealment. En-masse anterior retraction post first premolar extractions was carried out with modified force vectors in the three groups based on anchorage type [Molar, Mini-implant and Infrazygomatic crest (IZC) bone screws]. Volumetric root loss and linear dimensional changes were blindly assessed on initial (T0) and final (T1, end of space closure) CBCT scans. Normality distribution of values was done using Shapiro-Wilk's test. ANOVA and Post-hoc Tukey HSD test were done to compare measurements between groups at significance levels (P < .05).
Forty patients were analysed (14, 14, and 12 in three groups). Significant volumetric loss was noted in all groups. Central incisors demonstrated a significant reduction in IZC group (81.5 ± 21.1 mm ) compared to conventional (50.1 ± 26.5 mm ) and mini-implant groups (76.1 ± 27.6 mm ). Canines demonstrated a significant reduction in mini-implant group (108.9 ± 33.9 mm ) compared to conventional (68.8 ± 42.5 mm ) and IZC groups (103.1 ± 29.1 mm ). Regarding linear parameters, central incisors and canines revealed significant root length reduction in both skeletal anchorage groups. Lateral incisors showed no significant changes between groups.
Intrusive force vectors generated during skeletally anchored retraction can predispose anteriors to an increased risk of resorption. Greater loss of root volume was noted in the centrals and canines when retracted with skeletal anchorage.
Small sample size and variations during CBCT acquisition.
Low-dose CBCT scans were taken at T0 and T1 treatment intervals.
正畸治疗中的牙根吸收与力的施加方向和大小作为主要病因相关。需要通过三维分割来检测牙齿结构体积变化的严格对照试验，以评估牙根吸收的定量性质。
通过锥形束计算机断层扫描（CBCT）叠加，评估三种不同力向量（有和没有骨支抗）在上颌前牙内收过程中牙根吸收（RR）的严重程度。
三臂平行随机临床试验（RCT）。
42名（16名男性，26名女性）患者（年龄17 - 28岁），恒牙列伴有双颌前突，采用区组随机化（1:1:1比例）和分配隐藏，随机分为三组，每组14名患者。根据支抗类型[磨牙、微型种植体和颧牙槽嵴（IZC）骨螺钉]，在三组中采用改良力向量进行第一前磨牙拔除后的整体前牙内收。在初始（T0）和最终（T1，间隙关闭结束时）CBCT扫描上，对牙根体积损失和线性尺寸变化进行盲法评估。使用夏皮罗 - 威尔克检验对数值进行正态分布检验。进行方差分析和事后Tukey HSD检验，以比较组间在显著性水平（P < 0.05）下的测量值。
分析了40名患者（三组分别为14名、14名和12名）。所有组均观察到显著的体积损失。与传统组（50.1 ± 26.5 mm³）和微型种植体组（76.1 ± 27.6 mm³）相比，IZC组中切牙的体积损失显著减少（81.5 ± 21.1 mm³）。与传统组（68.8 ± 42.5 mm³）和IZC组（103.1 ± 29.1 mm³）相比，微型种植体组尖牙的体积损失显著减少（108.9 ± 33.9 mm³）。关于线性参数，两个骨支抗组的中切牙和尖牙牙根长度均显著减少。侧切牙组间无显著变化。
骨支抗内收过程中产生的侵入性力向量可使前牙牙根吸收风险增加。采用骨支抗内收时，中切牙和尖牙的牙根体积损失更大。
样本量小以及CBCT采集过程中的变化。
在T0和T1治疗间隔期间进行了低剂量CBCT扫描。
