Medical Journal of the Islamic Republic Of Iran

en Ultrasonographic Evaluation of the Masseter Muscle in Skeletal Malocclusions (Class I, II, and III) Radiology Radiology Original Research Original Research Background: There is limited research on the sonographic view of people with skeletal malocclusions. Therefore, this study aimed to evaluate the sonographic findings of the masseter muscle in patients with skeletal malocclusions.    Methods: In this descriptive study, 48 patients aged 15-20 years with skeletal class I, II, and III malocclusions (n = 16) who were referred to Mashhad Dental School for treatment were selected. The masseter muscle was evaluated by ultrasound, including transverse and longitudinal scans on both sides of the face in resting and contraction states. The age, gender, muscle thickness, muscle pattern (Malocclusion were classified based on A-point, nasion, B-point (ANB): 0< ANB <4 as class I, ANB > 4 as class II, ANB < 0 as class III), side of chewing, and body mass index (BMI) parameters were measured for each patient. Paired t-tests compared masseter muscle states; ANOVA assessed differences among malocclusion groups.    Results: The most commonly observed pattern in the masseter muscle of patients with class III skeletal malocclusions was type II, and in people with class II malocclusions was type I. There was a positive and significant correlation between the thickness of masseter muscle and BMI in each group separately (P < 0.001). However, the masseter muscle pattern did not show a significant correlation with BMI, gender, and age. A significant difference was observed between the thickness of the masseter muscle in the resting and contracted states in each group (P < 0.001).    Conclusion: This study showed that skeletal malocclusions can affect the pattern and internal structure of the masseter muscle in the anterior-posterior dimension of the face. Ultrasound can be a suitable diagnostic tool for these patients.   Ultrasound, Skeletal Malocclusions, Masseter Muscle, Thickness, Muscle Pattern 683 690 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-8863-1&slc_lang=en&sid=1 Mahrokh Imanimoghaddam imaniM@mums.ac.ir 200319475328460089506 200319475328460089506 No Department of Oral and Maxillofacial Radiology, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Fahimeh Farzanegan farzaneganf@mums.ac.ir 200319475328460089507 200319475328460089507 No Department of Orthodontics, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran Mohammad Taghi Shakeri Shakerimt@mums.ac.ir 200319475328460089508 200319475328460089508 No Department of Epidemiology and Biostatistics, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran Farzaneh Soleymani Farzaneh.soleimani@gmail.com 200319475328460089509 200319475328460089509 No Oral and Maxillofacial Radiologist, Neyshabur Health Center, Neyshabour, Iran Zahra Jamali Paghaleh JamaliZ4011@mums.ac.ir 200319475328460089510 0009-0006-7692-9387 Yes Department of Oral and Maxillofacial Radiology, School of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran