Cone-beam CT evaluation of temporomandibular joint in skeletal class Ⅱ female adolescents with different vertical patterns / 北京大学学报(医学版)

OBJECTIVE@#To compare temporomandibular joint (TMJ) morphology and position among skeletal class Ⅱ female adolescents with different vertical patterns using cone-beam CT (CBCT).@*METHODS@#Diagnostic CBCT images of 80 female patients aged 11 to 14 years were assessed retrospectively. According to subspinale-nasion-supramental angle (ANB) and Frankfort horizontal plane-gonion-gnathion angle (FH-GoGn), the participants were categorized into four groups (20 subjects each), i.e. class Ⅰ normal angle (group 1, 0°≤ANB < 4°, 22°≤FH-GoGn≤32°), class Ⅱ low (group 2, ANB≥4°, FH-GoGn < 22°), normal (group 3, ANB≥4°, 22°≤FH-GoGn≤32°) and high angle (group 4, ANB≥4°, FH-GoGn > 32°). Cephalometrics, morphology and position of TMJ were measured in Dolphin software. Using paired-samples t test to analyze TMJ symmetry, One-way analysis of variance (One-way ANOVA) and Chi-square tests to detect differences among the groups. The correlations between cephalometrics and TMJ measurements were also analysed within the skeletal class Ⅱ patients.@*RESULTS@#(1) Analysing TMJ morphologic symmetry, some measurements differed statistically although the mean diffe-rences were negligibly relative to their values. No statistically significant difference was found among the groups though group 4 showed the highest probability of condylar position asymmetry (65%). (2) Comparing group 1 with group 3, statistical difference was found in condylar position (χ2=6.936, P < 0.05) instead of morphologic measurements. Anterior and concentric condylar position were more frequently observed in group 1, yet posterior position was more prevalent in group 3. (3) In groups 2, 3, and 4, statistically, group 2 had the deepest glenoid fossa depth (H2&4=10.517, P=0.002), biggest superior (LSD-t2&3=3.408, LSD-t2&4=5.369, P < 0.001) and lateral (LSD-t2&3=2.767, LSD-t2&4=3.350, P=0.001) joint spaces, whereas group 4 showed the shortest condylar long axis diameter (H2&4=13.374, P < 0.001), largest glenoid fossa vertical distance (LSD-t2&4=4.561, P < 0.001, LSD-t3&4=2.713, P=0.007), smallest medial (LSD-t2&4=-4.083, P < 0.001) and middle (LSD-t2&4=-4.201, P < 0.001) joint spaces. The posterior condylar position proportion gradually increased from groups 2 to 3 to 4. Correlation analysis revealed ANB correlated with anterior joint space positively (r=0.270, P=0.037) and condylar long axis angle negatively (r=-0.296, P=0.022). FH-GoGn correlated with superior (r=-0.488, P < 0.001), posterior (r= -0.272, P=0.035), mesial (r=-0.390, P=0.002), middle (r=-0.425, P=0.001), and lateral (r=-0.331, P=0.010) joint spaces, articular eminence inclination (r=-0.259, P=0.046), as well as condylar long axis diameter (r=-0.327, P=0.011) negatively, and glenoid fossa depth (r=0.370, P=0.004) positively.@*CONCLUSION@#TMJ characteristics of skeletal class Ⅱ sagittal pattern mainly reflected in condylar position rather than morphology. TMJs of different vertical patterns differed more in joint spaces, position of condyle and glenoid fossa than in morphologic measurements. Vertical position of glenoid fossa and proportion of posterior condyle increased gradually from hypodivergent to hyperdivergent. Highest glenoid fossa position, maximum ratio of posterior positioned condyle, smallest joint spaces, shallowest glenoid fossa depth, and narrowest condylar long axis diameter were found in skeletal class Ⅱ high angle group, which means that patients with this facial type have considerable joint instable factors, and we should especially pay attention when orthodontic treatment is carried out on them.

The effects of activator treatment on the hard and soft tissue profile of different skeletal patterns / 实用口腔医学杂志

Objective:To evaluate skeletal,dentoalveolar and soft tissue profile changes by activator therapy in patients with different skeletal patterns of Class Ⅱ1 malocclusions.Methods:22 subjects(10 girls,12 boys,mean age 11.5 ±0.67 years) in the mixed or early permanent dentition,were included and divided into low angle(n =15) and average angle(n =7) groups on the basis of skeletal pattern.All patients were treated with a traditional activator.The skeletal,dentoalveolar and soft tissue profile changes were compared on lateral cephalograms before and after treatment.Statistical analysis was performed with t-test of SPSS 13.0 at a level of significance of P ＜ 0.05.Results:Activator treatment in these growing patients resulted in a correction of the skeletal Class Ⅱ relationship (decrease of ANB,Wits and NA-Pg),an advancement of the mandibular structures(increase of Co-Pg and L1-APg),and changes of the teeth(increase of L6-MP).The changes of Wits,NA-Pg and L1-APg value of low and average angle groups were 1.34° ± 1.82 ° and 3.50 ° ± 1.77°,(3.06 ± 2.00) mm and (5.80 ± 3.17) mm,(-1.16-± 1.74) mm and (-2.83 ± 1.48) mm respectively(P ＜0.05).No statistical significance was found in the soft tissue profile changes whether intra-class or inter-group comparison.Conclusion:The activator appliance is effective in treating growing patients with mandibular deficiency,and mandibular reconstruction,in patients with average angle it is more effective than in those with low angle.

A lateral cephalometric study of perioral soft tissue of the sbjects with ClassⅡDivisionⅠand various verti-cal patterns / 实用口腔医学杂志

Objective:To study the perioral soft tissue characteristics of the subjects with ClassⅡDivisionⅠand various vertical pat-terns. Methods:Lateral cephalograms of 90 adults ( half men, half women) were divided into 3 groups based on GoGn-SN angle:low angle, normal angle and high angle(n=30). The perioral soft tissues were measured and compared for the determination of the vertical skeletal variables influencing soft tissue characteristics. Results: The subjects with low angle showed significantly smaller values than those with high angle for basic lower lip thickness and lower lip length(P<0. 05). Most measurements of soft tissue thickness were greater in men than in women in all groups, especially for basic upper lip thickness and upper lower lip thickness(P<0. 05). Conclu-sion:Orthodontists need to pay more attention to the differences of perioral soft tissue in the subjects with various vertical patters to ob-tain balance of the facial harmony in orthodontic treatment.