Ability to control directional lip-closing force in skeletal class III patients

Ayumi Maruyama; Kazuhiro Yamada; Toru Kageyama; Tatsuya Naramoto; Kanako Fukasawa; Yuji Masuda

doi:10.1111/joor.13561

Ability to control directional lip-closing force in skeletal class III patients

J Oral Rehabil. 2023 Nov;50(11):1261-1269. doi: 10.1111/joor.13561. Epub 2023 Jul 19.

Authors

Ayumi Maruyama¹, Kazuhiro Yamada², Toru Kageyama¹, Tatsuya Naramoto¹, Kanako Fukasawa¹, Yuji Masuda^{3

4}

Affiliations

¹ Department of Orthodontics, Matsumoto Dental University, Nagano, Japan.
² Asunaro Pediatric Dental Clinic, Toyama, Japan.
³ Division of Oral and Maxillofacial Biology, Institute for Oral Science, Matsumoto Dental University, Nagano, Japan.
⁴ Department of Oral and Maxillofacial Biology, Graduate School of Oral Medicine, Matsumoto Dental University, Nagano, Japan.

PMID: 37437190
DOI: 10.1111/joor.13561

Abstract

Background: The relationship between the maximum lip-closing force (LCF) and malocclusion has long been studied. Recently, a method to measure the ability to control directional LCF from eight directions (upper, lower, right, left and the four directions in between) during lip pursing was established.

Objective: It is considered important to evaluate the ability to control directional LCF. The aim of this study was to investigate the ability of skeletal class III patients to control directional LCF.

Methods: Fifteen skeletal class III patients (mandibular prognathism group) and 15 people with normal occlusion (normal occlusion group) were recruited. The maximum LCF and the accuracy rate (the ratio of the matched time in which the participant was able to keep the LCF in the target range over a total time of 6 s) were measured.

Results: The maximum LCF was not significantly different between the mandibular prognathism group and the normal occlusion group. The accuracy rate in the mandibular prognathism group was significantly lower in all six directions than that in the individual normal occlusion group.

Conclusion: As the accuracy rate in all six directions was significantly lower in the mandibular prognathism group than that in the normal occlusion group, occlusion and craniofacial morphology might influence lip function.

Keywords: function; lip; malocclusion; mandible; muscle; prognathism.