Maxillofacial growth changes after maxillary protraction therapy in children with class III malocclusion: a dual control group retrospective study

Xu et al. BMC Oral Health (2024) 24:7 https://doi.org/10.1186/s12903-023-03790-6 BMC Oral Health Open Access RESEARCH Maxillofacial growth changes after maxillary protraction therapy in children with class III malocclusion: a dual control group retrospective study Shukui Xu1†, Yang Liu1†, Yan Hou1, Yinghui Li1, Xiaolei Ge1, Linna Wang1, Liru Zhao1 and Wensheng Ma2,3* Abstract Purpose To investigate the balance between post-treatment effect and continued nature growth after maxillary protraction treatment in patients with skeletal class III malocclusion. Methods 31 patients aged 8.79 ± 1.65 years with skeletal Class III malocclusion had been treated with maxillary protraction and the treatment lasted an average of 1.16 years. The average observation duration after treatment in the maxillary protraction group was 2.05 ± 0.39 years. In the control groups, a sample of 22 patients (9.64 ± 2.53 years) with untreated skeletal class III malocclusion and 24 patients (9.28 ± 0.96 years) with skeletal class I malocclusion were matched to the treatment group according to age, sex and observation period. The mean observation interval of the control groups was 2.39 ± 1.29 years in the class III group and 1.97 ± 0.49 years in the class I group. Results The active orthopedic treatment effect showed a opposite trend to the natural craniomaxillofacial growth effect after treatment in many aspects. In the observation duration of treatment group, decrease in ANB, Wits appraisal and BAr-AAr were statistically significant compared to class I control group (p < 0.001), and there was a significant increase in NA-FH (P < 0.001) which was contrary to class III control group. Treatment group presented a significant increase in Gn-Co (P < 0.01) and Co-Go (P < 0.001), except for changes in the extent of the mandibular base (Pog-Go, P = 0.149) compared to class I control group. The vertical maxillomandibular skeletal variables (Gonial; MP-SN; MP-FH; Y-axis) in treatment group decreased significantly compared to those in class III control group (P < 0.01). U1-SN and L1-MP showed a significant increase, which was similar to the class I group (P > 0.05), and overjet decreased significantly relative to both of the two control groups (P < 0.05). Conclusion Maxillary protraction therapy led to stable outcomes in approximately 77.42% of children with Class III malocclusion approximately 2 years after treatment. Unfavorable skeletal changes were mainly due to the greater protrusion of the mandible but maxillary protraction did have a certain degree of postimpact on the mandibular base. † Shukui Xu and Yang Liu as co-first authors due to their equally contribution to this work. *Correspondence: Wensheng Ma Full list of author information is available at the end of the article © The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Xu et al. BMC Oral Health (2024) 24:7 Page 2 of 11 Protraction therapy does not fundamentally change the mode of maxillary growth in Class III subjects except for the advancement of the maxilla. Craniomaxillofacial region tend to restabilize after treatment and lead to skeletal growth rotation and more dentoalveolar compensation. Keywords Maxillary protraction therapy, Skeletal class III malocclusion, Stability, Growth, Orthopedic treatment Background Skeletal class III malocclusion is a common pathological phenomenon in clinical orthodontics and is characterized by maxillary retrognathism or mandibular prognathism alone, or these two situations can exist simultaneously [1]. Recently, some studies have achieved a consensus on early interventions for the development of skeletal class III malocclusion, and a series of orthopedic treatment approaches have been proposed [2, 3]. However, clinicians do not always have the chance to modify a patient’s aberrant Class III growth pattern at an early age, and relapse following orthopedic treatment continues to be a major clinical issue, as the long-term stability of maxillofacial growth improvement for skeletal class III malocclusion patients has inherent uncertainty [4, 5]. Given this, growth represents the main component of the uncertainty in class III malocclusion subjects, whether it is undergrowth of the maxilla or overgrowth of the mandible, as seen in those who relapsed severely, eventually leading to the final treatment option of orthognathic surgery in adults [6]. Maxillary protraction is one of the commonly used clinical approaches for skeletal class III malocclusion in young patients as a kind of dentofacial orthopedic treatment [7, 8], causing anterior movement of the maxilla and restricting or redirecting mandibular growth to some extent, leading to a clockwise rotation trend of the mandible and reducing the compensatory effects of dental inclinations [9, 10]. However, the remaining skeletal remodeling effect after maxillary protraction remains controversial. Several studies have indicated that the early use of maxillary protraction may have favorable stability, with a stable rate of maxillary bone growth after lifting the restriction from negative anterior overjet [11, 12]. While some studies have questioned whether the development of skeletal class III malocclusion can be changed and the precise growth mechanisms after maxillary protraction, they have indicated that excessive growth of the mandible after removal of the restrictive counterforce from maxillary protraction may cause relapse of the sagittal jaw-face relationship [4, 13, 14]. Therefore, it appears that the posttreatment stability of Class III malocclusion should focus on the correction of maxillary deficiency and the growth potential of the mandible. Considering that previous studies often focused only on the possibility of relapse after treatment by comparing with skeletal class III control group. Notably, a continued nature growth will still exists which is attributed to the fact that the treatment have been basically completed before the e (...truncated)