Ultrastructural Analysis of Masseter and Left Medial Pterigoid Muscles, After Unilateral Mandibular Molar Extraction: Experimental Study

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Maria Ivone Mendes Benigno; Edson Aparecido Liberti; Airton Mendes Conde Jr; Noélia Maria de Sousa Leal; Karla Emanuelle Lopes Rodrigues; Vanessa Benigno Mota & Eliane Maria Ingrid Amstalden


Twelve adult male Wistar rats (220 g average weight) were divided in 3 experimental groups: GI -15. GII – 30 and GIII – 60 days, after mandibular molar extraction, with three experimental animals and one control per group. Qualitatively, ultrastructural changes of protein filaments from myofibrils of these muscles and ipsilateral to the extractions were observed. Ultrastructure asymmetry and disorganization of Z line and I band, in the experimental group GII, of Medial Pterigoid muscle (MPT) were observed. The temporomandibular dysfunction, stimulated by the unilateral extractions of mandibular molars in rats may lead to modifications in the Z line and I band, which showed to be sensitive to this dysfunction. Changes in the MPT muscle, probably related to its own functional characteristics and major participation in the dynamics of mastication, compared to Masseter were also observed. However, the muscular fibres seem to adapt to the new conditions along the experiment.

KEY WORDS: Skeletal muscular fibre; Masticator muscles; Occlusal alterations; Temporomandibular joint; Transmission electron microscopy.

How to cite this article

BENIGNO, M. I. M.; LIBERTI, E. A.; CONDE JR., A. M.; DE SOUSA LEAL, N. M.; LOPES RODRIGUES, K. E.; MOTA, V. B. & AMSTALDEN, E. M. I. Ultrastructural analysis of masseter and left medial pterigoid muscles, after unilateral mandibular molar extraction: experimental study. Int. J. Morphol., 35(2):430-434, 2017.