A longitudinal study of normal asymmetric mandibular growth and its relationship to skeletal maturation

Introduction: Our aims in this investigation were to assess asymmetric mandibular growth relative to skeletal maturation and to determine whether asymmetric growth occurs during a period of high growth velocity. Methods: We evaluated lateral oblique and hand-wrist radiographs of 30 male and 30 female Class I participants in the Burlington Growth Study who were assessed at 3 time periods with the skeletal maturation index (SMI). The body, the ramus, the effective length, and the gonial angle on each side of the mandible were measured. Asymmetry between the right and left sides was analyzed with the SMI and for sex dependency. Results: The left ramus was consistently longer than the right in all evaluation periods (P <.05). The right body was consistently longer than the left in all evaluation periods (P <.05). The effective length showed no asymmetry until the last maturation group, when the right side was longer (P <.05). The gonial angle had no significant differences. Tests to determine differences between the sexes showed no significance in asymmetry, but the body, the ramus, and the effective length were longer in males than in females (P <.05). Conclusions: Asymmetry does not occur or increase during any specific growth period.