Márcio Vieira Lisboa

Influence of Laser Therapy and Muscle Relaxant on the Masseter Muscle under Occlusal Wear: An Ultrastructural Study

El objetivo del estudio fue analizar la influencia de la terapia laser de baja intensidad y del relajante muscular sobre las caracteristicas ultraestructurales del musculo masetero en el desgaste oclusal. 40 ratas macho Wistar, se dividieron al azar en cuatro grupos: grupo de control (GI), desgaste oclusal (G-II), laserterapia desgaste oclusal (G-III), y relajante muscular desgaste oclusal (G-IV). Bajo anestesia general por via intraperitoneal, los animales de los grupos II, III y IV sufrieron amputacion unilateral de las cuspides de los molares superiores e inferiores para simular una situacion de desgaste oclusal. El musculo masetero del G-III recibio la terapia con laser (830nm, 4J/cm2, 40mW, f ~ 2mm) despues del procedimiento el cual se repitio durante 14/30 dias. Los animales del G-IV fueron tratados con una inyeccion diaria de Dantroleno® (2,5 mg/Kg en 0,5 ml de H2O). Los animales fueron sacrificados con una sobredosis de anestesia general en los dias 14 y 30. Despues de la remocion de las cuspides el musculo masetero ipsilateral se extirpo y se dividio en dos, una mitad fue procesada para microscopia de luz y la otra para microscopia electronica. No hubo diferencias estadisticamente significativas entre cada grupo experimental y el control, asi como, entre los periodos en cada grupo experimental. Sin embargo, las fibras musculares en el G-II mostraron los cambios mas pronunciados. En conclusion no existe relacion causal entre las lesiones de las fibras musculares y la oclusion, a pesar que los signos de lesion de los tejidos musculares fue mas evidente en el grupo con desgaste oclusal. Los resultados indican una accion moderada ejercida por la terapia laser y de los relajantes musculares sobre el musculo esqueletico.

Assessment of the effect of the use of laser light or dantrolene on facial muscle under occlusal wear: a Raman spectroscopic study in a rodent model.

OBJECTIVE The aim of the present study was to use Raman spectroscopy to measure levels of CaPi in muscles under occlusal wear and treated with laser phototherapy (LPT) or muscle-relaxant therapy or both on rodents. BACKGROUND The etiology of temporomandibular disorders is multifactorial. Malocclusion may influence the masticatory muscles, causing fatigue. A major type of fatigue is the metabolic, caused by the increased accumulation of metabolites such as inorganic phosphate. Raman spectroscopy allows nondestructive analysis of the biochemical composition of tissues. METHODS The 30 male Wistar rats were randomly divided into three groups: occlusal wear (G-1), occlusal wear + LPT (G-2), and occlusal wear + muscle relaxant (G-3). Ten untreated animals were used for baseline data. Under intraperitoneal general anesthesia, animals of groups 1, 2, and 3 had unilateral amputation of molar cusps to simulate an occlusal-wear situation. The masseter muscle of G-2 received LPT (lambda830 nm, 4 J/cm(2), 40 mW, phi approximately 2 mm) after the procedure and repeated every other day for 14-30 days. Animals of G-3 were treated with a daily injection of dantrolene (2.5 mg/kg in 0.5 ml of H(2)O) beginning 24 h after cusp removal. Animals were killed with an overdose of general anesthetics at days 14 and 30 after cusps removal, and the ipsilateral masseter muscle was excised and divided into two parts. One part was routinely processed and underwent histologic analysis; the other was kept in liquid nitrogen for Raman spectroscopy. The mean value of the intensity of the peak 958 per centimeter was determined. RESULTS No morphologic changes were seen. Raman analysis showed significantly less Raman intensity in the laser group at 30 days (p < 0.01). CONCLUSION Occlusal wear did not caused morphologic alterations in the masseter muscle but resulted in changes of the levels of CaP(i) that were less compromising when the laser light was used.

An interview with Kotaro Tanimoto

If I had to describe Tanimoto Sensei using a single word I would say kindness. When I was attending the PhD course in Hiroshima University, I frequently looked at him and thought: “If I have the chance to be an educator, I would like to be like that man.” The generosity, respect and friendship he employed to treat the students is fascinating. By that time, Professor Tanimoto had just come back from his post-doc in the USA full of ideas and dreams. Since that, many of the ideas had become projects and many of the projects had become a real benefit for the patients. Tanimoto Sensei has an extensive and relevant scientific production and some of them are described in the next pages. I believe this interview is especially interesting because it is enriching to know how professors from the other side of the globe conduct orthodontic education and science. Finally, I would like to express my sincere gratitude to the other professors that assisted in this article and to Dental Press Journal of Orthodontics for the opportunity to conduct the present interview with Professor Tanimoto, a great friend of mine. Emanuel Braga – interview coordinator » DDS, Hiroshima University, Japan. » PhD in Orthodontics, Hiroshima University, Japan. » Head of Department, Department of Orthodontics, Hiroshima University Institute of Biomedical & Health Sciences, Japan.

Ultrastructural features of masseter muscle exhibiting altered occlusal relationship—a study in a rodent model

The role of occlusion on Tempormandibular Disorders (TMD) is still unclear, mainly regarding muscular function. The aim of this study was to evaluate the occlusion highlights on masseter ultra morphology. Twenty Wistar rats were randomly divided in four groups: 10 for control group, 10 for occlusal alteration group (CCO). Rats underwent unilateral amputation of the left inferior and superior molar cusps to simulate an occlusal wear situation. The rats of control group had no occlusal wear. Half of the animals of each group was sacrificed in 14 days after the occlusal consuming and half 30 days after the occlusal consuming. The masseter muscles ipsilateral to the amputated molars were excised and processed for light microscopy, electron microscopy. The light microscopy did not show differences between the groups. The electron microscopy was able to detect a degree of intracellular damage in muscle fibers of CCO group: swollen mitochondria with disrupted cristae and cleared matrix, signs of hypercontraction of I bands and myofibril disorganization.