Morphological and histochemical study of the masseter muscle after occlusal alteration

ABSTRACT

The aim of this study was to evaluate alterations in the masseter muscle of 30 male guinea-pigs submitted to occlusal alteration. The animals were divided into 2 equal groups, the control group (C) only submitted to surgical stress, and the occlusal altered group (T) submitted to teeth extraction. Each group was subdivided into 3 groups, with 5 animals, for the following studies macroscopy and vessels distribution, light microscopy and histochemical analysis, with animals' perfusion 2 months after surgery. Data were submitted to statistical analysis. Macroscopically, an anteroposterior orientation of the muscular fibers was found and statistical difference between C and T groups in width (p<0.05). Microscopically, C and T groups showed polygonal muscular fibers with variable diameters, and on the left side of the T group these differences were more pronounced. Histochemically, in both groups, the prevalence of intermediate reactivity fibers and several high reactivity fibers spread out in the deeper area was observed, with no significant differences between superficial fibers on both sides of C and T groups. It was possible to conclude that the masseter muscle in guinea-pigs was sensible to functional chewing alteration.