ABSTRACT
<p><b>OBJECTIVE</b>The relationship between occlusion and temporomandibular disorders (TMD) remains disputed. The related epidemiological studies have been carried out focused on the occlusal characteristics in motion, for example in protrusion, retrusion or laterally extension and on some of malocclusion features. Very few studies were carried out on the intercuspal occlusion which is the most important occlusal relationship. Angle's classification of occlusion and the relationship of over-jet and over-bite are two prominent features now generally used in clinical practice for occlusal evaluation. In present study two kinds of features of occlusion were compared among TMD patients, malocclusion patients and university student volunteers, who of the laters represented nature population.</p><p><b>METHODS</b>100 continued cases visiting our TMD Clinic during the year of 2 000 with complain of TMD problem, 100 malocclusion patients in continued orthodontic department records, and 268 university student volunteers were included. All subjects were with complete dentitions, except of age-related third or second molar tooth eruption difference. Study cast were obtained for all 468 subjects involved and following characters were studied. 1. Angle's classification; 2. Over-jet and over-bite relationship. Anteriorly it included cross-bite, cusp-to cusp bite, deep over-bite (without deep over-jet), deep over-jet (with or without deep-bite), open bite, and others. Posteriorly it included cross-bite, reverse cross-bite and others. 3. Abnormal occlusal index: For the purpose of quantitatively comparing the abnormal occlusal relationship of over-bite and over-jet, the occlusal index was introduced. The anterior continued abnormal was scored as 3 while posterior continued oclcusal abnormal scored as 5. The sum of the scores in the same subject was taken as his abnormal occlusion index.</p><p><b>RESULTS</b>1. Ratio of Angle's I patients in malocclusion group was significantly lower than those in TMD group and US group (P < 0.05), while the later two groups had no difference (P > 0.05). 2. The ratios of anterior cross-bite and deep over-jet were higher in malocclusion group than those in other two groups. No significant difference for the other kinds of abnormal over-jet and over-bite relationship were found among the three groups. 3. The abnormal occlusion index of malocclusion group was higher than that of US group, but not than that of TMD group which had no difference with US group either.</p><p><b>CONCLUSIONS</b>1. Aesthetic related anterior abnormal occlusion such as anterior cross-bite and deep-over-jet attract more attention of popular. But they had no relationship with TMD. 2. TMD patients had not significant occlusal features on Angle's classification and over-jet and over-bite relationship compared to malocclusion and nature population subjects.</p>
Subject(s)
Humans , Dental Occlusion , Malocclusion , Epidemiology , Students , Temporomandibular Joint Disorders , UniversitiesABSTRACT
Objective:To investigate the effect of partial p osterior teeth with reverse cross-bite at one side of mandible on the chewing m ovement. Methods: 16 university students with partial posterior teeth reverse cross-bite and 12 with normal occlusion were included, 5 cycles o f gum chewing movement with left and right side separately were recorded with K6 -Ⅰmandibular kinesiograph (MKG) for the trace and velocity. Results: ①The chewing movement recorded in frontal plane was with a typical cycl e in controls while that in reverse cross-bite individuals was vertically in an d/or out type (59.38%), as well as in and out in same direction type (21.88%). ②Chewing movement in reverse cross-bite patients was in posterior direction, together with a larger angle of closing trace to horizontal plane and higher che wing terminal velocity. Conclusion: Partial posterior teeth with reverse cross-bite at one side have significant effect on both direction and v elocity of chewing movement.
ABSTRACT
砄bjective:To elucidate the effects of gradually induced occlusal disorder on the expression of TGF ?1 in temporomandibular condyle of monkey. Methods:In a monkey after extraction of right upper first molar and left lower first molar, a fixed orthodontic appliance was used to cause the adjacent teeth inclined to the space and to occlude with opposite in coordinately. Another monkey was used as the control.8 months later, the animals were sacrificed and bilateral temporomandibular condyles were examined with histologic and immunohistochemical methods.Results:In the animal with teeth extraction, degenerative changes were found in anterior medial part of condyles, the thickness of condylar cartilage decreased significantly, especially in the anterior parts of medial and central thirds, and also the intermediate part of medial third ( P
ABSTRACT
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.
