Concentración de la enzima AST (aspartato aminotransferasa) en dientes sometidos a fuerzas ortodónticas intrusivas / Enzyme concentration AST (aspartate transaminase) teeth in orthodontic forces under intrusive

Introducción: Reportes en la literatura describen, como las fuerzas ortodónticas aplicadas durante los movimientos dentales conllevan a reacciones pulpares, alteraciones y molestias en un tratamiento de ortodoncia. La aspartato aminotransferasa (AST) es una enzima catalogada como un indicador de necrosis celular; sin embargo, es necesario evaluar su actividad en dientes sometidos a las diferentes fuerzas que se aplican durante un tratamiento ortodóntico. Objetivo: Comparar las concentraciones de aspartato aminotransferasa en tejido pulpar de dientes sometidos a fuerzas ortodónticas intrusivas y dientes libre de fuerzas. Método: Se realizó un estudio cuasi-experimental de boca dividida en 34 premolares superiores procedentes de 20 sujetos que requerían extracción de los mismos para fines ortodónticos. 20 premolares fueron expuestos por 48 horas a fuerzas intrusivas (75 g/fuerza). Los dientes contralaterales fueron usados como grupo control. Se extrajo el tejido pulpar y se midió la concentración de AST. Se tuvo en cuenta una significancia estadística de p<0,05. Resultados: Al realizar las comparaciones de las concentraciones de la enzima en ambos grupos no se encontró una diferencia estadísticamente significativa (p= 0,436). El grupo control mostró una concentración promedio de 1,78±1,13 U/mg mientras que los premolares expuestos a fuerzas intrusivas reportaron una media de 1,94±1,2 U/mg. Conclusión: La actividad de la AST a nivel del tejido pulpar no tiene variación significativa al inducir movimientos intrusivos con fuerzas aproximadas de 75 g/fuerza en la muestra estudiada

Background: Reports in the literature describe as orthodontic forces applied during dental movements lead to pulp reactions, alterations and discomfort in orthodontic treatment. Aspartate aminotransferase (AST) is an enzyme classified as an indicator of cell necrosis; However, it is necessary to evaluate their activity in teeth subjected to various forces applied during orthodontic treatment. Objective: To compare aspartate aminotransferase concentrations in teeth pulp tissue subjected to intrusive orthodontic forces and forces free teeth. Method: A quasi-experimental study of mouth divided into 34 premolars from 20 subjects requiring removal thereof for orthodontic purposes was performed. 20 premolars were exposed for 48 hours to intrusive forces (75 g/force). Contralateral teeth were used as control group. the pulp tissue was removed and the concentration of AST was measured. statistical significance of p <0.05 was taken into account. Results: When making comparisons of enzyme concentrations in both groups not a statistically significant difference (p= 0.436) was found. The control group showed an average concentration of 1.78±1.13 U/mg while the premolars exposed to intrusive forces reported an average of 1.94±1.2 U/mg. Conclusion: AST activity level does not vary pulp tissue by inducing movements intrusive forces approximate 75 g/force

Changes in the expression of aromatase, estrogen receptor α and ß in mandibular condylar cartilage of rats induced by disordered occlusion.

BACKGROUND: Estrogens play an important role in modulating the morphology and function of temporomandibular joints (TMJs), which is suggested to act via estrogen receptors (ERs). The present study was to investigate the expression of aggrecan, collagen type II (Col II), Col X, aromatase, ERα and ERß in degenerative changes of mandibular condylar cartilage. METHODS: Forty male and 40 female 8-week-old rats were enrolled in this study. In experimental groups, the disordered occlusion was created by moving the first molars mesially and the third ones distally. Immunohistochemistry and real-time PCR were performed at the end of the second or fourth week. RESULTS: Degenerative changes, characterized by interrupted continuity of hypertrophic layer, pyknotic and eosinophilic lesion with few nuclei, areas filled with eosinophilic nuclei, were observed in more joints from female experimental groups than male ones. However, thickening changes in hypertrophic layer were only found in male experimental groups. The gene expression of Col II, Col X and aggrecan increased in 4-wk male experimental subgroup (both P < 0.01), but decreased in 2-wk and 4-wk female subgroups (P < 0.05). The gene expression of ERα decreased in 2-wk male and female experimental subgroups (both P < 0.01), however, that of ERß increased except the 2-wk female experimental subgroup (all P < 0.01). The expression of aromatase decreased in both male and female experimental subgroups (all P<0.01). CONCLUSIONS: Mandibular condylar cartilage responses differently to the disordered occlusion in male and female rats. The levels of locally synthesized estrogen, ERα and ERß may have limited attribution, if any, to the sex-specific cartilage response.

Identification of matrix metalloproteinases and their tissue inhibitors type 1 and 2 in human masseter muscle.

Changes in masticatory muscle structure and function are either developmental, as seen in anomalies of facial form, or adaptive, as seen during procedures such as orthognathic surgery and functional-appliance orthodontic therapy. Remodelling of muscle extracellular matrix is pivotal in these processes. This turnover is mediated via members of the family of enzymes known as matrix metalloproteinases (MMP) and inhibited by the tissue inhibitors of metalloproteinases (TIMP). The aim here was to investigate the in vivo pattern of expression and distribution of MMPs and TIMPs in masseter muscle of humans with both normal and abnormal facial forms. Masseter muscle biopsies were taken from 10 patients, four with long-face syndrome and six normal controls as confirmed by cephalometry. Immunohistochemical techniques were used to show the pattern and distribution of MMPs and TIMP proteins in the muscle. Zymography of tissue extracts was used to determine the presence of MMP activity. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the presence of MMP and TIMP-2 mRNA. MMP-1 was expressed around the individual muscle fibres, especially in those fibre surfaces in contact with the interstices of the connective tissue and around blood vessels. MMP-9 staining was less intense and was expressed in the interstices of the connective tissue and around blood vessels. Zymography of protein extracts confirmed that MMP-9 activity was present. MMP-2 and MMP-3 were not expressed in the samples, although MMP-2 mRNA could be detected by RT-PCR and its activity could be detected by zymography. Intense TIMP-1 staining was present around each muscle fibre, in the interstices of the connective tissue and surrounding blood vessels; TIMP-2 mRNA could be detected in all samples. These staining patterns were seen in all biopsies examined and were irrespective of the facial form of the donor. These findings provide evidence that the mechanisms required for matrix remodelling are present in the human masseter muscle.

Collagenolytic and phosphatase activity in the rat mandible after functional protrusion.

The effect of chronic mandibular protrusion on the collagenolytic and phosphatase activity of several mandibular bone sites and the condylar cartilage was evaluated. Ninety-three male Sprague-Dawley rats were equally divided into two experimental and one control group. One experimental group wore a protrusive appliance for 2 weeks, the other for 4 weeks. All animals were killed at 59 days of age. Collagenolytic, alkaline and cid phosphatase activities were determined in the condylar cartilage, the subchondral bone and condylar neck, and in the gonial angle and coronoid process. In the cartilage and subchondral bone, the protrusive appliance caused a reduction in collagenolytic and alkaline phosphatase activity. In the condylar neck, it caused a large increase in collagenolytic activity and a decrease in alkaline phosphatase activity in both experimental groups. In the gonial angle and coronoid process, the appliance increased the collagenolytic activity only in the 2-week group. In the 4-week group, the alkaline phosphatase and collagenolytic activities were not different from the activities in those tissues in the control animals. Thus a protrusive appliance induced quantitative changes in enzyme activities in condylar cartilage and mandibular bone. The increase in collagenolytic activity (representing increased bone resorption) occurred typically in areas of muscle attachment and might have been the result of the neuromuscular changes induced by the protrusive appliance. The recovery to normal values of collagenolytic activity in the coronoid process and gonial angle of the 4-week group suggests that at these sites the muscles (and subperiosteal bone) might have adapted to their new biomechanical environment after the longer period of appliance wear.