Mandibular arch width changes during mandibular movement

Abstract

I recorded and analysed mandibular arch width changes between the right and left first molars during opening and protrusive jaw movement, together with incisal movements and electromyograms of the inferior head of the lateral pterygoid muscle (LPt). In five subjects, the average maximum mandibular arch width decrease was 397.7μm during opening, and 585.0μm during protrusion. There was a significant correlation between the decrease in mandibular arch width and electromyographic activity of the LPt (p<0.01). The results suggest that the LPt is the primary cause of decreases in the mandibular arch width during opening and protrusion.