Occlusion is a term for the contact relation between upper and lower dentitions.It is a three dimensional relationship.The vertical occlusal contact relation includes convex-to-concave contact relation between structures on occlusal surfaces of the upper and lower teeth at status of intercuspal occlusion,as well as that during protrusion,retrusion and lateral excursive movements.Occluding function depends on the contact condition of occlusion.However,the morphological criterion of the vertical occlusal contact is still lacking.Widely practical criterion for dental treatment includes only mesial-distal relation,such as one-to-two teeth contact relation between upper and low dentitions,and labial/buccal-lingual relation,such as over jet and over bite.To establish a vertical occlusal contact criterion that meets the need for individual occlusal treatment is one of the main subjects in Occlusion field.

0.05).(2)The relative tooth attrition:significant differences between CTS and control group in upper premolar lingual cusp and lower first molar buccal cusp were found.(3)Tooth cracked direction:it was mesial-distal direction in 91.67% maxillary premolar and 88.89% maxillary second molar in CTS but no obvious direction taxis in first molar and mandibular second molar in CTS.Conclusion:There are close correlations between insufficient tooth attrition in maxillary premolar lingual cusp,mandibular first molar mesial buccal cusp and CTS.

Objective:To investigate the effects of occlusal adjustment in the treatment of TMD . Methods: 7 cases of TMD were treated by occlusal adjusment and occlusal contact points were measured with T-scan II system before and after treatment . VAS pain analysis table was used to evaluate the pain control effect of occlusal adjustment method. Results:The number of occlusal contact points increased obviously after occlusal adjustment,and distribution of contact on two sides tended to be balanced.Pain release was indicated by VAS table . Conclusion: Occlusal ajustment method is necessary for the treatment of TMD

Objectives: To investigate the characteristics and their functional significance of TMJ disc and its attachment. Methods: Each of the 23 TMJs from 12 cadavers were divided into quadrants sagitall y, and total 92 histological slices were obtained and stained with HE.The morpho logical characteristics of the samples was observed microscopically. Results: ①Both temporal posterior and anterior mandibualr attachment s were loose while mandibular posterior and anterior temporal attachments were d ense in which the fibers run anterior posteriorly. ②Fibers in the intermediate zone ran predominantly in anterior posterior direction while those in both ant erior and posterior bands were mixed with transverse fibers. ③At the posterior portion of disc there were 33 out of 92 slices from 6/12 cadavers (11/23 TMJs) s howed the structure of "the fourth band" which was featured by dense fibers alik e those of inner disc. There were 36 out of 92 slices from 6/12 cadavers (10/23 TMJs) showed the structure of "turned fibers" which was featured by a sudden tu rning of fibers from the thick posterior band back and downward, providing an angle like sign. Conclusions: There is great difference o f fiber direction in various parts of disc and its attachments, reflecting the functional demands.

Objective: To investigate the expression and distribution of G protein and protein kinase C (PKC) under the mechanical pressure in rabbit mandibular condylar chondrocytes (MCCs) and to study the role of G protein in PKC signalling pathway. Methods:MCCs from two-week-old New Zealand rabbits were cultured. After treatment under continuous pressure of 90 kPa for 60 min or 360 min by hydraulic pressure controlled cellular strain unit, the expression of G?q/11 protein was examined by Western Blot. The expression and distribution of PKC was observed by immunocytochemical staining. Results:Gaq/11 protein in MCCs treated by 90 kPa for 60 min and 360 min was increased by 163.7% and 65.8% respectively(P0.05). PKC in control cells distributed uniformly in the cytoplasm. After been pressed under 90 kPa for 60 min,PKC translocated to the membrane and, partly,into nuclei. When the pressure prolonged to 360 min, PKC distributed uniformly again in cytoplasm. By treatment of G protein inhibitor, the translocation of PKC under 90 kPa of 60 min was not observed. Conclusion:Feasible pressure may promote G protein expression and activate PKC. The activation of PKC signalling pathway is mediated by G protein.

Centric Relation ; Dental Occlusion, Centric ; Humans ; Orthodontics

Objective: To investigate the distribution of abnormal occlusion of permanent dentition in adolescents. Methods: 304 Junior university students aged 16- 18 years old were investigated with their occlusion casts according to the Angle classification and the relationshop of over-jet and over-bite in both anterior and posterior teeth. Asymmetrical Angle category was given to those whose bilateral classifications were different. Results: 19.73% of the subjects were found with normal occlusion. Among the abnormals 58. 05%, 8. 90%, 8. 90% and 24. 15% were found with Angle Ⅰ, Ⅱ, Ⅲ and asymmetrical Angle category respectively. Anterior edge-to-edge relationship, cross-bite, deep over bite, deep-over jet and open bite were 12.71 %, 11.02 %, 5.08%, 5.08 % and 2.12% respectively, posteriorly cross-bite, reverse crosss bite and combination of the two were 19.07%, 17.37% and 0.85 % respectively. Conclusion: The asymmetrical Angle malocclusion and abnormal over-jet and over-bite of both anterior and posterior teeth stand a large ratio in Junior university students.

Objectives: To study the clinical meaning of condyle-form asymmetry and its osseous changes shown on TMJ images of lateral oblique transcranial projection and lateral tomography. Methods: 113 patients with partial posterior teeth lose were enroled in the study.Among them 25 were with temporomandibular disorder (TMD group),39 with slight TMD sings (sub-TMD group) and 45 without TMD(TMD-free group). Radiographs were taken and studied for each patient. Results: It was found that the condyle form asymmetry and osseous changes were not significantly different among the three groups. Osseous change was related to the number of teeth-lose (P0.05). The symptoms and signs of TMD had close relationship with occlusal interferences. Conclusions: The changes shown on TMJ images do not show close relationship with TMD symptoms and signs. Occlusal interferences resulted from teeth-lose are related to the clinical symptoms and signs of TMD.

Objective: To investigate the characters of the ageing changes in TMJ of New Zealand rabbit from 7 to 10 months old. Metho ds: 12 New Zealand rabbits aged 7,8,9 and 10 months old and 3 in eac h age group, were killed under anesthesia. Bilateral TMJs were histologically examined with HE stainnig. Results: Quite similar histolo gical structures were found in the TMJs in different age groups. Very few change s occurred in the fibre layer of osteo-articular surface. The thickness of the proliferate layer was decreased slightly in anterior and middle part saggitally, resulting in comparable increase of the hypertrophy layer with age. No hypertro phy layer was found in the cartilage over tempora articular surface. The thickne ss of the cartilage-like osteo layer was uneven, the thickest part was in the area towards condyle anterior slope and without age change. The thickness of d isc increased a little bit with age. Conclusion: The thick ness of the cartilage over TMJ articular surface of New Zealand rabbit at the a ge from 7 to 10 months old changes a little. The layer structures keep considera bly constant.

0.05).During unilateral contact maximal biting EMG activity of the temporalis-anterior muscle on the bitting-side was higher than that on the disoccluded side(P0.05).Conclusion: Vertical distance occlusion contact may affect the EMG activity of temporalis-anterior muscle but not on that of masseter muscle during the central biting.