›› 2018, Vol. 38 ›› Issue (11): 1375-.doi: 10.3969/j.issn.1674-8115.2018.11.019

• Original article (Clinical research) • Previous Articles     Next Articles

Comparison of alveolar bone changes in maxillary anterior area secondary to different kinds of retraction method of anterior teeth: a cone-beam computed tomography study

ZHOU Di, WU Yan, WANG Yun-ji, FAN Xiao-ping   

  1. Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences; Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Stomatological Hospital of Chongqing Medical University, Chongqing 401147, China
  • Online:2018-11-28 Published:2018-12-15
  • Supported by:
    The Second Batch of Scientific and Technological Projects in Chongqing, 2014 No.42 of Yubei District Education Finance; Program for Innovation Team Building at Institutions of Higher Education in Chongqing in 2016, CXTDG201602006; Project SupportedChongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education; Fund of Chongqing Municipal Committee for Health and Family Planning, 2015MSXM054

Abstract: Objective · Using cone-beam computed tomography (CBCT) to compare alveolar bone changes in maxillary anterior area secondary to maxillary incisor retraction adjunct with tip (R&Tp) and retraction adjunct with torque (R&Tq) movements. Methods · Forty teenagers with Angles class Ⅱ division 1 malocclusion who had completed orthodontic treatment met the inclusion criteria and were selected, and all of their 160 maxillary incisors were classified into two categories, namely R&Tp group and R&Tq group, according to their actual retraction pattern. Pre- and post-treatment CBCT images and 3D measurement software were used to measure and analyze tooth retraction and alveolar bone height and thickness changes within each group and to compare treatment changes of teeth and alveolar bone between two groups. Results · Anterior teeth in each group were intensively retracted and uprighted, with a longer retraction distance of incisal edge and a greater retraction angle of teeth in R&Tp group than in R&Tq group (both P0.000). Alveolar bone thickness was significantly decreased at L3 and P1 in R&Tp group (both P<0.05), while it was significantly decreased at P1 and P2 in R&Tq group (both P<0.05). Total alveolar bone thickness decreased at T1 in R&Tp group (P0.000) and at all levels in R&Tq group (all P0.000). Finally, alveolar ridge height in two groups dropped both in the buccal (both P0.000) and palatal (both P0.000) sides, with a more prominent extent in the palatal side, and ridge height dropped most in palatal side of the teeth in R&Tq group. Conclusion · The buccal root apex area and the palatal alveolar ridge area of alveolar bone in the R&Tp group and the cervical and middle area of incisor root in palatal side of alveolar bone in the R&Tq group are high-risk areas for alveolar bone resorption when anterior teeth in teenagers with Angles class Ⅱ division 1 malocclusion are intended to have en masse retraction.

Key words: cone-beam computed tomography (CBCT), anterior teeth retraction, alveolar bone remodeling, Angles class Ⅱ division 1 malocclusion

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