Anatomical Characteristics of the Lateral Pterygoid Muscle in Mandibular Prognathism

Hwikang Kim,Jaehyun Kang,Hunjun Lim,Dongsun Shin,Bongchul Kim,Seewoon Kim,Jun Lee

doi:10.3390/app11177970

Abstract

Mandibular prognathism is one of the most concerning subjects in the oral and maxillofacial fields. In our previous studies, we attempted to clarify the etiology of mandibular prognathism. They revealed that one of the major characteristics of mandibular prognathism was the lower volume/length ratio of the mandibular condyle and body compared to normal, and the masseter muscle showed parallelism with this. This study aimed to evaluate the relationship between mandibular prognathism and the lateral pterygoid muscle by measuring the orientation and volume/length ratio of the lateral pterygoid muscle. Computed tomography was used to calculate the volume/length ratio of the lateral pterygoid muscle in 60 Korean individuals. Mimics 10.0 and Maya version 2018 were used to reconstruct the surface area and surface planes. The results showed that the prognathic group showed smaller lateral pterygoid volume/length ratios compared to the normal group (p < 0.05). In addition, the normal group displayed a larger horizontal angle (p < 0.05) to the mandibular and palatal planes than the prognathic group. This demonstrated that the mechanical drawback of the lateral pterygoid in the prognathic group is associated with mandibular prognathism.

Highlights

Mandibular prognathism, which brings about esthetic and functional problems, is one of the major issues in the oral and maxillofacial fields
Similar to the masseter muscle, which attaches to the mandibular body, the lateral pterygoid attaches to the main part of the mandible, the condyle
We found two important points related to the masseter muscle: (1) the volume/length ratio of the masseter for the normal group was larger than that for the prognathic group; (2) the orientation of both deep and superficial masseters of individuals in the normal group were more vertical [10]

Summary

Introduction

Mandibular prognathism, which brings about esthetic and functional problems, is one of the major issues in the oral and maxillofacial fields. Younger patients have other ways to manage mandibular prognathism, such as timing treatment options, predicting the mandibular growth, and regulating the growth pattern [3,4]. Many studies have attempted to investigate the relationship between mandibular growth and influence factors. A previous study has shown that the lateral pterygoid muscle plays a physiological role in regulating the growth rate of the condylar cartilage [8]. The quantitative characteristics of prognathic and normal jaws were revealed by skeletal unit and masseter muscle analyses [9,10]. Similar to the masseter muscle, which attaches to the mandibular body, the lateral pterygoid attaches to the main part of the mandible, the condyle. It is possible to assume that the two muscles are the main muscles related with mandibular growth in prognathism

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