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CC BY 4.0 · Eur J Dent 2023; 17(02): 381-386
DOI: 10.1055/s-0042-1749364
Original Article

Evaluation of Skeletal Changes after Mandibular Setback Surgery Using the NM-Low Z Plasty Technique in Skeletal Class III Patients

Sarunpong Imampai 
1   Division of Orthodontics, Faculty of Dentistry, Thammasat University, Pathum Thani, Thailand
,
Siripatra Patchanee
1   Division of Orthodontics, Faculty of Dentistry, Thammasat University, Pathum Thani, Thailand
2   Thammasat University Research Unit in Mineralized Tissue Reconstruction, Thammasat University, Pathum Thani, Thailand
,
Awiruth Klaisiri
3   Division of Restorative Dentistry, Faculty of Dentistry, Thammasat University, Pathum Thani, Thailand
4   Thammasat University Research Unit in Restorative and Esthetic Dentistry, Thammasat University, Pathum Thani, Thailand
,
Narissaporn Chaiprakit 
2   Thammasat University Research Unit in Mineralized Tissue Reconstruction, Thammasat University, Pathum Thani, Thailand
5   Division of Oral and Maxillofacial Surgery, Faculty of Dentistry, Thammasat University, Pathum Thani, Thailand
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Abstract

Objective The study's objective was to evaluate skeletal changes in 38 skeletal class III patients following mandibular setback surgery using NM-Low Z plasty.

Materials and Methods Thirty-eight skeletal class III patients (ANB angle lower than 0) who underwent the NM-Low Z plasty technique for surgical mandibular setback procedure at Thammasat University Hospital between January 2017 and March 2020 were included in the study: 29 patients had two jaw surgeries, and 9 patients had one jaw surgery. An additional 14 patients had genioplasty. Three lateral cephalograms were traced and digitized with Dolphin Imaging software: T0, T1, and T2. The distance between the B-point and the SN7 perpendicular line defined immediate changes after surgery (T1-T0) and stability after surgery (T2-T1). The reliability test included 6 cephalograms retraced after 2-week interval. At point B, the principal result was horizontal movement forward.

Statistical Analysis The analysis used paired t-tests.

Results The mean mandibular setback was 9.78 mm, and the mean skeletal relapse was 2.61 mm, or 26.69%. Statistical analysis showed postoperative differences (p < 0.05). Vertical measurement in B-SN7 reduced immediately and postoperatively.

Conclusion Postoperatively, the mandible relapsed significantly forward and upward. Rotational relapse is a concern with NM-Low Z plasty in hypo-/normodivergent patients.

Keywords

malocclusion - mandibular setback - orthodontics - orthognathic surgery - skeletal class III - skeletal relapse


Publication History

Article published online:
04 July 2022

© 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

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