Cephalometric Measurements in Mixed Dentitions with Class I Normal Occlusion

Objectives: Using cephalometric (C) radiographs of mixed dentition (MD) subjects who had Class I normal  occlusion in adolescence, (1) describe C norms for 8 year old children, (2) test hypothesis that C variables are similar in genders, and (3) test hypothesis that 8 and 12 year old C measurements taken by JJG are similar.

Methods: Longitudinal radiographs from 19 males (M) and 19 females (F) in the Iowa Growth Study [IRB permission] with Class I normal occlusion in permanent dentition (PD) were measured in MD at 8 years (Jessica) and 12 years in PD (Jeremy).   C variables (11 angular, 3 linear) were measured with protractor and ruler. Intra-rater reliability correlations (r = .9700-.9978, p < 0.0001) and inter-rater reliability correlations (r=.9548-.9986, p < 0.0001) were acceptable.  Student’s t-tests/Wilcoxon compared genders and ages.   Histograms of MD variables were generated.   

Results: One variable, N-Me mm, differed between MD genders (M > F) (p=0.0152).  Comparison of MD and adolescent PD variables revealed significant differences in both genders for six variables: SNB° (F: p=0.0209; M: p=0.0085), SNPog° (F: p=0.0000; M: p=0.0005), N-Me mm (F: p=0.0000; M: p=0.0000), MP : SN° (F: p=0.0053; M: p=0.0003), ┴ : ┬ ° (F: p=0.0052; M: p=0.0012), ┬ : FH° (F: p=0.0221; M: p=0.0406), and ┬ : NB mm (F: p=0.0023; M: p=0.0040).  Other MD-PD differences were males, ┴ : SN° (p=0.0080) and females, SNA° (p=0.0209), ┬ : MP° (p=0.0434), and ┴ : APog mm (p=0.0098).    

Conclusions: The null hypothesis for differences between MD genders was accepted for all variables except N-Me mm.  The null hypothesis for differences between MD and PD variables was rejected for 10 F variables and 8 M variables.  Norms for age 8 are recommended.     

Support University of Iowa College of Dentistry Dows Research Award.