骨量、牙量和切牙复发：正畸稳定性的三维分析。

Bone volume, tooth volume, and incisor relapse: a 3-dimensional analysis of orthodontic stability.

出版信息

Am J Orthod Dentofacial Orthop. 2010 Dec;138(6):778-86. doi: 10.1016/j.ajodo.2009.02.032.

DOI:10.1016/j.ajodo.2009.02.032

Abstract

INTRODUCTION

Orthodontic relapse is a common and significant problem. Few risk factors have been identified, and the role of bone has only recently been investigated. The purpose of this study was to examine the influence of alveolar bone volume and tooth volume on dental relapse.

METHODS

The sample was chosen from the postretention database at the Department of Orthodontics of the University of Washington in Seattle. Based on the 10-year postretention (T3) irregularity index (II), 40 relapse subjects (T3 II > 6 mm) and the 40 most stable subjects (lowest T3 II < 1.5 mm) were identified for the study. Cone-beam computed tomography (CBCT) scans were taken of the posttreatment (T2) models. Total volume (V) was defined laterally by the distal contact points of the canines and vertically by the cusp tips of the canines to a depth 7 mm below the most inferior gingival margin. Alveolar volume (AV) was defined as the region below a vertical line at the most inferior gingival margin and tooth volume (TV) as the region above that line. The ratio TV:AV was calculated. Logistic regression analysis was used to determine the association between relapse and AV, and to adjust for potentially confounding variables (TV, initial II, sex, age, retention time, and postretention time). Mandibular cortical thickness (CT) measured on T2 lateral cephalograms was used as another measure of bone quantity. Nine patients from the graduate orthodontic clinic who had pretreatment CBCT scans were identified. V, AV, and TV were measured on both the in-vivo scans and the scans of their dental casts to verify the method.

RESULTS

The relapse group had significantly greater V and AV and significantly lower CT. TV:AV was not different between the groups. T2 II was found to be a significant predictor of relapse based on logistic regression analysis, whereas AV was not. CT was poorly correlated with AV. V and AV were highly correlated between in-vivo scans and dental cast scans, whereas TV approached significance.

CONCLUSIONS

Although postretention relapse was associated with increased V and AV, when other variables were controlled, bone volume was not a significant predictor of relapse.

摘要

简介

正畸复发是一个常见且严重的问题。虽然已经确定了少数几个风险因素，但骨骼的作用直到最近才被研究。本研究的目的是探讨牙槽骨量和牙齿量对牙齿复发的影响。

方法

该样本选自西雅图华盛顿大学正畸系的保留期后数据库。根据 10 年保留期后（T3）不整齐指数（II），确定了 40 名复发患者（T3 II > 6mm）和 40 名最稳定患者（最低 T3 II < 1.5mm）作为研究对象。对治疗后（T2）模型进行锥形束 CT（CBCT）扫描。总容积（V）由犬牙的远侧接触点在外侧定义，由犬牙的牙尖在垂直方向定义，深度为最下牙龈缘下方 7mm。牙槽骨容积（AV）定义为最下牙龈缘下方的垂直线区域，牙体容积（TV）定义为该线以上的区域。计算 TV:AV 的比值。使用逻辑回归分析来确定复发与 AV 之间的关联，并调整潜在的混杂变量（TV、初始 II、性别、年龄、保留时间和保留后时间）。在 T2 侧位头颅侧位片上测量下颌皮质厚度（CT）作为骨量的另一种测量方法。从研究生正畸诊所确定了 9 名有治疗前 CBCT 扫描的患者。在活体扫描和牙模扫描上测量 V、AV 和 TV，以验证该方法。