A Novel Method to Quantify Longitudinal Orthodontic Bone Changes with In Vivo Micro-CT Data.

Yubo Fan,Chao Wang,Li Cao,Chongshi Yang

doi:10.1155/2018/1651097

Abstract

Orthodontic tooth movement (OTM) is the result of region-specific bone modeling under a load. Quantification of this change in the alveolar bone around a tooth is a basic requirement to understand the mechanism of orthodontics. The purpose of this study was to quantify subregional alveolar bone changes during orthodontic tooth movement with a novel method. In this study, 12 Sprague-Dawley (SD) rats were used as an orthodontic model, and one side of the first upper molar was used to simulate OTM. The alveolar bone around the mesial root was reconstructed from in vivo micro-CT images and separated from other parts of the alveolar bone with two semicylinder filters. The amount and rate of OTM, bone mineral density (BMD), and bone volume (BV) around the root were calculated and compared at 5 time points. The results showed that the amount of tooth movement, BMD, and BV can be evaluated dynamically with this method. The molar moved fastest during the first 3 days, and the rate decreased after day 14. BMD decreased from day 0 to day 14 and returned from day 14 to day 28. BV deceased from day 0 to day 7 and from day 14 to day 28. The method created in this study can be used to accurately quantify dynamic alveolar bone changes during OTM.

Highlights

Orthodontic tooth movement (OTM) results from the modeling and remodeling of the alveolar bone under a prolonged and moderate load
Different processes of bone modeling can be observed at different sides under the same orthodontic load. e pressure side and tension side show bone resorption mediated by osteoclasts and bone apposition mediated by osteoblasts, respectively [1, 2]. erefore, partitioning the alveolar bone around the root is necessary when evaluating the amount and characteristics of bone changes in orthodontics
The main approach is 2D measurement by determining the distance of the landmarks on the molars with X-ray films [7, 8]. This method suffers from more errors caused by inconsistent X-ray magnification, projection angulation, and other factors, such as interference from artifacts caused by other anatomic structures

Summary

Introduction

Orthodontic tooth movement (OTM) results from the modeling and remodeling of the alveolar bone under a prolonged and moderate load. Erefore, partitioning the alveolar bone around the root is necessary when evaluating the amount and characteristics of bone changes in orthodontics Bone morphologic measures, such as bone mineral density (BMD), bone volume (BV), and other microstructure parameters, were calculated by definition of regions of interest (ROIs) in previous studies [3,4,5]. In these studies, a cube of the alveolar bone near the root was extracted as a ROI to evaluate bone resorption and apposition. E objective of this study was to accurately quantify dynamic bone resorption and apposition with this novel method and to evaluate the modeling of the alveolar bone on tooth movement

Materials and Methods

Image Processing

Discussion