Ultrastructural Analysis of Masseter and Left Medial Pterigoid Muscles, After Unilateral Mandibular Molar Extraction: Experimental Study/Analisis Ultrastructural de los Musculos Masetero y Pterigoideo Medial Izquierdo, despues de la Extraccion Molar Mandibular Unilateral: Estudio Experimental

• Published in: International journal of morphology 2017-06, Vol.35 (2), p.430
• Main Authors: Benigno, Maria Ivone Mendes, Libe, Conde, Airton Mendes, Jr, de Sousa Leal, Noelia Maria, Rodrigues, Karla Emanuelle Lopes, Mota, Vanessa Benigno, Amstalden, Eliane Maria Ingrid
• Format: Article
• Language: Spanish
• Subjects: Analysis; Animal experimentation
• ISSN: 0717-9367

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. Doce ratas Wistar machos adultos (220 g de peso promedio) se dividieron en 3 grupos experimentales: GI-15, GII-30 y GIII-60 dias, despues de una extraccion molar mandibular. En cada grupo se dispusieron tres animales experimentales y un animal como control. Cualitativamente, se observaron cambios ultraestructurales de filamentos de proteinas de miofibrillas de estos musculos masticadores ipsilaterales a las extracciones. Se observo asimetria de la ultraestructura y desorganizacion de la linea Z y la banda I, en el musculo pterigoideo medial del grupo experimental GII, (MPT). La disfuncion temporomandibular, estimulada por las extracciones unilaterales de los molares mandibulares en ratas, puede conducir a modificaciones en la linea Z y en la banda I, que mostraron ser sensibles a esta disfuncion. Los cambios en el musculo pterigoideo medial, se debieron, probablemente, con sus propias caracteristicas funcionales y una mayor participacion en la dinamica de la masticacion, en comparacion con el musculo masetero. Sin embargo, las fibras musculares parecen adaptarse a las nuevas condiciones a lo largo del experimento. PALABRAS CLAVE: Fibra muscular esqueletica; Musculos masticadores; Alteraciones oclusales; Articulacion temporomandibular; Microscopia electronica de transmision.