RESUMEN
The purpose of the present study was to investigate the immunohistochemical distribution of matrix metalloproteinase-12 [MMP-12] in the rabbit mandibular condyle following experimental induction of anterior disc displacement. The right temporomandibular Joint [TMJ] of nine rabbits was exposed surgically and all discal attachments were severed except for the posterior attachment. The disc was then repositioned anteriorly. The left TMJ served as a control. Mandibular condyles were excised at 2, 4 and 7 weeks following surgery. These specimens were prepared and stained by Haematoxyline and eosin [H and E] for routine histological examination. For immunohistochemical staining with MMP-12, five micron thick sections were cut and mounted on positively charged slides. After two weeks the current study revealed the presence of numerous intense immunoreactivities at the bone cartilage interface. Some of the chondrocytes showed intense granuliform reactivity for MMP-12. The subchondral bone showed also intense immunoreactivities surrounding both Haversian and Volkmann canals as well as along the entire borders of large resorbed bone marrow spaces. These immunohistochemical results concomitant with the breakdown of the articular cartilage and degradation of the extracellular matrix as well as splitting phenomena at the bone cartilage interface observed histologically during this period. After four weeks, the articular cartilage was lost and the mandibular condyle showed formation of coarse fibered woven bone. The immunohistochemical staining for MMP-12 was relatively weak at the surface of the woven bone and appeared to be moderate in the deep layer. After seven weeks, the mandibular condyle showed irregular remodeling of bone with negligiable immunoreactivity in the remodeled bone trabeculae. On the other hand, in the control group the MMP-12 was relatively weak at the surface of the woven bone and appeared to be moderate in the deep layer. After seven weeks, the mandibular condyle showed irregular remodeling of bone with negligiable immunoreactivity in the remodeled bone trabeculae. On the other hand, in the control group the MMP-12 immunoreactivites were noticed relatively weak mainly around the Haversian canals. In conclusion, the increased expression of MMP-12 in rabbit mandibular condyle was detected obviously after two weeks rather than after four and seven weeks postoperatively. These results provide evidence for a potential role of MMP-12 in the pathogenesis of osteoarthritis and imply that the inhibition of MMP-12 may be potentially therapeutic for the treatment of degenerative joint diseases
RESUMEN
This study was conducted to evaluate as well as to compare the ability of two different screw systems used as a fixation devices in maxillofacial trauma, orthognathic surgery and bone augmentation. A quantitative assessment using the image analysis software was used to assess the ability for new bone formation as well as maturation at the screw-bone interface. The histological as well as the histochemical results revealed more bone formation in response to titanium screws more than absorbable ones. This variability in osteogenesis was found to be statistically significant after 2 and 4 weeks of post-surgical follow up periods while after 8 weeks this difference did not showed any statistical significance. These data suggested that the biological fixation of both systems is challenging and although early osteogenesis of titanium screw system is more favorable, yet the absorbable screw system represents a good alternative solution
RESUMEN
This retrospective study analyzed lateral profile soft and hard tissue changes that occurred shortly two months after bilateral sagittal split ramus osteotomy [BSSRO] and set back mandibular surgery in both horizontal and vertical planes, it also assessed the significance and correlations between the soft tissue changes and the dentoskeletal changes. The subjects enrolled were six patients suffering from mandibular prognathism [4 males and 2 femals] operated with BSSRO and rigid fixation. This study was conducted using digitized lateral profile cephalometric radiographs immediate presurgical and 2 months after surgery. Soft and hard tissues were traced and landmarks located in relation to an X and Y coordinate system. Variables corresponding to the horizontal and vertical relationships of the skeletal and soft tissue profiles and incisal relationships were measured. The statistical elaboration of the data made by means of paired t-test and Pearson's coefficient of correlation to examine relationships between tissue and hard tissue changes. The assessment of the results showed changes of the lower anterior 1/3 of the facial profile characterized by significant decrease in height as a result of cranial movement of soft landmarks of the lip [subnasale and superior sulcus] and chin landmarks [gnathion and pogonion]. On the other hand significant cranial movement was found including bony landmarks A point B, pogonion and menton. Also facial profile changed as a result of significant posterior movement of bony tissues and soft tissues below the stomion with increase in the lower facial 1/3 convexity. Both incisors showed upward movement and retroclination which was more significant in lower incisors. A strong correlation was found between both soft and hard tissue changes. In conclusion, lateral cephalometric analysis in this study proved that there was short term lateral profile soft and hard tissue changes after BSSRO and set back surgery with significant correlation between changes. Cephalometry is a valuable method used for assessment of these changes in spite of the existent limitations
RESUMEN
This study was designed to evaluate long term structural and positional changes of the fractured condyles after open reduction and rigid internal fixation by mini dynamic compression plates [mini-DCP] using computerized tomography [CT] through assessment of the different radiographic variables including condylar angles, distances and measurements of superior joint spaces. Six patients were included in the study [6 males] with age ranged from 19 to 39 years. Assessment of the unilateral displaced condylar fractures is done after 13 years of follow up. The results of this study showed negative structural changes and insignificant differences between the various linear and angular measurements of the fractured and non-fractured joints, which indicates proper repositioning of the fractured condyles. In conclusion, the use of maxillomandibular fixation [MMF] before and during placement of the plates, surgical approach, proper reduction using mini dynamic plates with compression were all factors contributed to the proper three-dimensional repositioning of the fractured condyles. Computerized tomography is an acceptable method for assessment of the structure and position of the condyles as it allows accurate linear and angular measurements from different scans in different planes without superimnosing structures projecting over them