OBJECTIVEThis study investigates the differences in condylar position between centric relation (CR) and maximum intercuspation (MI) in Angle's Class II orthodontic patients before treatment.

METHODS80 cases, who were Angle's Class II pretreatment patients, and 50 cases, who were normal(ideal) occlusion were accepted. Dental casts were mounted on Panadent articulator with CR bite record, taken by bilateral manipulation and load testing. The differences in condylar position between CR and MI in all three spatial planes were measured using the Panadent condylar position indication (CPI).

RESULTS(1) The positive rate of CR-MI discrepancy was 92.50%(74 cases) in the group of Angle's Class II malocclusion and 10.00% (5 cases) in the group of normal occlusion(P< 0.001). 2)74.32% (55 cases) CR-MI discrepancy in 74 cases in the group of Angle's Class II pretreatment patients were coincidence discrepancy. (3)91.25% patients in the group of Angle's Class 11 malocclusion and 66.00% in the group of normal occlusion present occlusion interferences which located at the posterior teeth.

CONCLUSIONThe results suggested that orthodontists should be aware of a high incidence of condylar displacement in Angle's Class ii pretreatment patients, and measure condylar displacement before the start of comprehensive orthodontic treatment to unmask real jaw relationships and avoid possible misdiagnoses.

Adult ; Centric Relation ; Dental Arch ; Dental Articulators ; Dental Occlusion ; Female ; Humans ; Male ; Malocclusion ; Mandibular Condyle

To validate the use of the Index of Complexity, Outcome and Need (ICON) in assessing orthodontic treatment need among 12-13 year-olds in southern China, we determined the threshold value of ICON based on Chinese orthodontists' judgments. The samples consisted of 335 students in grade 7 from 16 randomly selected middle schools in Chengdu, China. Three associate professors provided ICON scores for each participant and the results were compared with the gold standard judgments from 25 experts on treatment needs. Based on the gold standard, 195 casts belonged to the treatment category, while the rest 140 belonged to the no-treatment category. With the international cutoff point of 43, the sensitivity and specificity of the ICON score were 0.29 and 0.98.The best compromise between sensitivity and specificity in Chengdu, compared with the gold standard, was found at a cutoff point of 29, and the sensitivity and specificity were 0.88 and 0.83. When used to evaluate the treatment need of 12-13 year-olds in southern China, the international ICON cutoff value did not correspond well with Chinese orthodontists' judgments; a lower cutoff value of 29 offered a greater sensitivity and specificity with respect to expert orthodontists' perception of treatment need.
Adolescent ; Child ; China ; epidemiology ; Cross-Cultural Comparison ; Data Collection ; Dental Health Surveys ; methods ; standards ; Female ; Health Services Needs and Demand ; statistics & numerical data ; Humans ; Male ; Malocclusion ; diagnosis ; epidemiology ; Needs Assessment ; statistics & numerical data ; Observer Variation ; Orthodontics, Corrective ; standards ; statistics & numerical data ; Reference Values ; Reproducibility of Results ; Sensitivity and Specificity