Longitudinal predictability of AF-BF value in Angle Class I patients.

AF-BF is a linear cephalometric measure of the anteroposterior jaw relationship in the sagittal plane. A retrospective, longitudinal study was made to determine the mean Caucasian American AF-BF values at ages 8 and 18 years for 30 male and 32 female participants of the Bolton Growth Study. Mean AF-BF values (+/- s.d.) for males were 7.3 +/- 2.7 mm at 8 years and 6.5 +/- 4.2 mm at 18 years. Mean AF-BF values (+/- s.d.) for females were 6.7 +/- 2.1 mm at 8 years and 5.2 +/- 2.9 mm at 18 years. No significant difference was found between the mean AF-BF values for males and females at either age group (P < 0.05). The decrease in AF-BF mean values with increasing age both for males and females was statistically significant. The correlation (r) for the AF-BF values was 0.49 (P < 0.05) for females and 0.86 (P < 0.05) for males. With increasing age, the mean difference between ANB values for females was 1.40 +/- 1.60 and 1.10 +/- 1.40 for males. The correlation of ANB angle and AF-BF provides a clinically useful tool for the cephalometric assessment of anteroposterior sagittal discrepancies of maxillary and mandibular denture bases.