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Objective: To study the effects of estrogen on the degenerative changes of condylar cartilage and subchondral bone in rats. Methods: 18 female SD rats aged 6 weeks were divided into control(C),unilateral anterior cross-bite(UAC) and UAC treated with estrogen(UAC + E) groups(n = 6). UAC metal prosthesis was cemented to the left incisors of maxilla and mandible of the rats in group UAC and UAC + E. Rats in UAC + E group were given pexitoneal injection of 80 μg 17β-estradiol per day. The rats in group C were untreated. Animal were sacrificed at the 4th weeks. The micro-structure of subchondral bone was observed by Micro-CT scanning. HE staining,Safranin O staining,immunohistochemical staining,TUNEL staining and TRAP staining for the observation of pathological changes of histomorphology,extracellular matrix,chondrocyte apoptosis in condylar cartilage,and osteoclasts number in subchondral bone. Results: UAC and UAC + E group showed evident osteoarthritis(OA)-like lesions. Compare with UAC group,there was a significant decrease in the expression of proteoglycan(P ＜ 0. 05),type Ⅱ collagen(P ＜ 0. 01),and a significant increase in the number of apoptotic chondrocytes(P ＜ 0. 01) in UAC + E group. As for subchondral bone,the BV/TV,Tb. Th parameters in C and UAC + E groups were significant higher than in UAC group(P ＜ 0. 01),while the BS /BV,Tb. N,Tb. Sp parameters and the osteoclasts number in C and UAC + E groups were significant fewer than in UAC groups(P ＜ 0. 01). There was no significant difference in bone ultra-parameters and osteoclasts number between C and UAC + E groups(P＞ 0. 05). Conclusion: In the model of rat TMJOA induced by unilateral anterior crossbite prosthesis,supra-physiological level of estrogen can reverse bone loss in subchondral bone,but accelerate the degradation of condylar cartilage.
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<p><b>OBJECTIVE</b>To compare the ultra-microscopic changes of periodontal Ruffini's corpuscle induced by different patterns of tooth movement, and investigate the influence of different changes of the periodontal mechanical environment on the periodontal mechanoreceptor.</p><p><b>METHODS</b>Thirty-two eight-weeks-old SD rats were divided into control group (n = 4), none-extraction group (n = 12) and extraction group (n = 12), and none-extraction group and extraction group were further divided into three subgroups, namely 3 day and 14 day and 28 day. For control group, no intervention was performed. For none-extraction group and extraction group, the following interventions were conducted. In none-extraction group, the maxillary left and mandibular right third molars were moved distally. In extraction group, the maxillary left third molar was moved distally, and the bilateral mandibular third molars were extracted. The ultra-structures of periodontal Ruffini's corpuscle in the periodontal ligament of the distal root of the bilateral maxillary third molars were observed under the transmission electron microscope.</p><p><b>RESULTS</b>The ultra-structrural changes in the none-extraction group were mainly characterized by degeneration or abnormal distribution of mitochondria in the axon terminal, which were almost recovered at 28 d. In the extraction group, the changes were mainly characterized by deficiency or abnormal elongation of the Schwann sheath and were not recovered at 28 d.</p><p><b>CONCLUSIONS</b>The ultra-structures of periodontal Ruffini's corpuscle might be influenced by tooth movement and occlusal changes, and the mechanorecepting function of it might be affected by changes of the periodontal mechanical environment.</p>
Subject(s)
Animals , Rats , Mechanoreceptors , Physiology , Molar , Molar, Third , Periodontal Ligament , Tooth Movement Techniques , Tooth RootABSTRACT
<p><b>OBJECTIVE</b>To study the effect of gradually induced occlusal disorders on the expression of basic fibroblast growth factor (bFGF) of condylar cartilage in rat.</p><p><b>METHODS</b>The model of gradually induced occlusal disorders was established in rat. The expression of bFGF was examined by SABC technique of immunohistochemistry. The expression of bFGF was analyzed by amount of positive cells.</p><p><b>RESULTS</b>bFGF was expressed positively in the proliferative cell layer, maturative layer and hypertrophical cell layer in the rat mandibular condyle cartilage. In control group, expression of bFGF increased from 2-week-old to 6-week-old, then it had a decrease during experiment. Compared with the control group, bFGF of experiment group was increasing at 2 week, 6 week and 8 week during experiment. But there was decreaseing at 4 week. There was no difference between young experiment group and the adult experiment group.</p><p><b>CONCLUSION</b>The gradually induced occlusal disorders may lead to significant increase of expressiong of bFGF in condyle cartilage, which suggests that the bFGF may be involve in the procedure of repairing process of articular cartilage.</p>
Subject(s)
Animals , Rats , Cartilage , Cartilage, Articular , Fibroblast Growth Factor 2 , Mandibular CondyleABSTRACT
objective: To evaluate the clinical effect of various materials used in the reconstruction of mandibular defects retrospectively. Methods: 467 patients with mandibular defects were treated with various implantation materials during last 30 years and 395 of them were followed up.Results: 217 were satisfied with their mouth opening, occlusion and maxillofacial contour after sugery, 189 of them had bone transplanation and 28 had non biomateria transplantaion; 91 were partly satisfied, 72 of them had bone trasplantation and 19 had non biomateria; 87 were not satisfied, 11 of them had bone trasplantation and 76 had non biomaterial. Conclusion: Bone especially auto bone transplantation is more effective than non biomaterial in the reconstruction of mandibular deffects.
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Objective: To investigate the root canal curvatures of anterior teeth in the Han nationality in Shaanxi province.Methods:392 permanent anterior teeth were examined by indirect digital radiography both from labiolingual and mesiodistal directions according to Schneider method, root canal curvatures were analyzed by electronic rule.Results:Root canals of the anterior teeth were mainly of type I. High rate of root canal curvature was found in maxillary canines (68.5%), and most of curves were in the apical third. There was a relationship between the root canal curvatures of maxillary canine and age(P=0.03). Conclusion:Root canal curvatures of maxillary canine are complicated,especially in maxillary canines. The root canal curvatures of maxillary canine decreased with aging.
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Objective:To investigate the effect of tooth wear on the morphological features of mandibular first molars. Methods:15 extracted mandibular first molars with tooth wear and 15 without wear were investigated. Data about the morphological features of tooth were collected through the general measurement and the image measurement by electronic meter. Results:①In non-tooth-wear group, mesiodistal width of tooth was greater than buccolingual width(P0.05); ②The vertical distance between the lowest point of pulp chamber roof and occlusal surface in non-tooth-wear group was greater than that in tooth-wear group(P05); ④The distance between distolingual pulp horn and distal proximal plane was greater than that between mesiolingual pulp horn and mesial proximal plane in both two groups(P0.05). Conclusion:For different parts of tooth, the effect of tooth wear differs. As for mandibular first molars, the distal part of occlusal surface and the buccal part of distal proximal plane are susceptible to tooth wear, which is mainly due to occlusal factors and the features of biomechanical system.
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Objective:To investigate the expression of estrogen receptor ? and ?(ER? and ER?) in temporomandibular joints(TMJs) of Sprague-Dawley rats.Methods:The expression of ER? and ER? in TMJs was examined by SABC technique of immunocytochemistry, meanwhile the co-expression of them was detected by double-staining technique of immunocytochemistry.Results:①Intense ER? and ER? immunoreactivity was localized in the hypertrophic layer of condyle cartilage,and some immunoreactivity was found in osteocytes of mandible and temporal bone. ②The immunoreactivity of ER? and ER? was found in both nuclei and cytoplasms. Most of immunoreactivity of ER? was localized in nuclei, while ER? was distrubuted more evenly. ③The expression of ER? was wider than that of ER?.Conclusions:TMJ is one of target organs of estrogen.The expression of ER? is different from that of ER?,which suggests there may be different mechanisms directed by ERs.