Masseter Muscle Thickness and Dental Arch Width

"Objectives:" Various studies have shown an association between the functional capacity of the masticator muscles and craniofacial morphology . Since there is a correlation between masticator muscle size and craniofacial width , a similar association with dental arch width might be expected to exist . The purpose of this study was to investigate the correlation between the ultrasonographic thickness of masseter muscle and dental arch width of tooth jaws .

"Methods:" 44 subjects( 22males and22 females) aged 21_28 years with class 1 occlusion and orthognatic face were considered to measure the thickness of the masseter muscle ultrasonographically( with a 7/5 MHZ linear array transducer) . Records were performed bilaterally both in reciprocal relaxed and contracted conditions of masseter muscles. Alginate impressions were taken from all subjects , models were cast in dental stone and intermolar (the distance between the lingual surfaces of the first permanent molars) and intercanine width( the distance between the cingulum of canines) were measured with caliper .

"Results:"'There was a statistically significant correlation between gender and muscle thickness in relaxed and contracted condition in both sides( PV=0/001, PV=0/003 ) . The correlation between gender and arch width in mandibular first molar area , but not in any other locations , was significant ( PV= 0/037 ) . There was a direct significant correlation between masseter muscle thickness in right side and arch width ( intermolar and intercanine )in maxilla (PV= 0/050 , PV= 0/037 ) and intercanine width in mandible ( PV=0/028 ).

"Conclusion:" The findings of this study indicated that the thickness and functional capacity of the masseter muscle may be considered as one of the factors influencing the width of the maxillary dental arch( inter molar and intercanine) and intercanine mandibular dental arch .