Cephalograms of 30 male and 28 female participants in the Iowa Growth Study were used [IRB approval]. Dial calipers were used to measure mandibular length between articulare-pogonion (Ar-Pg). Standing height measurements were obtained from the Iowa Growth Study. Spearman correlations were used to correlate growth of standing height and articulare-pogonion in subjects with CINO (15 males and 15 females) and CIIM (15 males and 13 females). The Fisher Z method tested for significant differences in correlation coefficients of growth measures.
Result: CINO correlation coefficients ranged from -0.01 to 0.7. No CINO males had significant correlations but CINO females aged 9 and 10 had significant correlations (r=0.7235 p=0.0052, r=0.5804, p=0.0479). CIIM correlation coefficients ranged from -0.2 to 0.8. CIIM males age 13 and females age 11 had significant correlations (r=0.8333, p=0.0102, r=0.6993, p=0.0114, respectively). The only significant difference in correlations between the two occlusion groups occurred at age 9 in females (r=0.7235 [CINO]; r= -0.0070 [CIIM], p=0.0448). Growth curves for mandibular length and for standing height were similar but key differences occurred in growth acceleration in both genders in both occlusion groups. Conclusion:
Correlations between growth in standing height and length of mandible in CINO and CIIM subjects were low to moderate positive. The correlations have minimal clinical application.
Study support: University of Iowa Dows Research Award
Keywords: Growth & development, Human, Occlusion and Orthodontics