Ultrasonographic evaluation of masseter muscle thickness in chronic areca nut/ tobacco chewers and oral submucous fibrosis patients

Abstract

The benign increase in the size of the masseter muscle is referred to as masseter muscle hypertrophy (MMH). It may affect unilaterally or bilaterally. Frequent and prolonged chewing of areca nut, betel quid, and tobacco exerts undue pressure on muscles of mastication. This may lead to hypertrophy of masticatory muscles, especially the masseter. The objective of the study is to evaluate the difference in cross-sectional thickness of masseter muscle at rest and at maximum clenching position using USG in chronic areca nut/tobacco chewers, OSMF patients, and the control group.The study included 20 chronic areca nut/tobacco chewers and 18 OSMF consecutive patients. The control group comprised of 42 age, sex, and body mass index-matched healthy individuals. Ultrasonographic measurements were performed in all the subjects in both contracted and relaxed states. Intergroup comparison of ultrasonographic cross-sectional thickness was done using ANOVA with post hoc.Masseter muscle thickness significantly increased in chronic chewers in both relaxed & contracted states bilaterally when compared to OSMF & control group. Muscle thickness decreased in the OSMF group compared to controls.In patients with chronic chewing habits without OSMF, due to prolonged chewing muscle thickness increased whereas, in OSMF patients, reduction in mouth opening leads to a decrease in bite force and consequent atrophy of muscle.