Growth modulation using functional appliances--cephalometric predictors of successful response.

Aim: The aim of this study was to determine any skeletal morphologic features evident on a pretreatment lateral cephalogram that may be used to predict improvement in the sagittal relationship during functional appliance therapy in Class II patients and compare changes between cases with and without a favorable response to growth modulation.

Method: Pretreatment and postfunctional lateral cephalograms were analyzed, and the change in the ANB angle was used to determine the skeletal response to treatment with a functional appliance. Based on the change in the ANB angle, the patients were divided into two groups of 12 patients each. Comparisons were made between the mean pretreatment (T1) cephalometric parameters of group I (skeletal) and group II (nonskeletal) to assess any pretreatment parameters that were significantly different between the groups. Changes due to functional appliance therapy from the pretreatment (T1) to postfunctional (T2) stage was measured as T2-T1 in both groups. The mean changes seen in group I and group II were then compared to assess the difference between changes brought about by growth modulation using functional appliances. Comparative statistical analysis of the data was done using one-way analysis of variance F test.

Results and conclusion: This study showed that not all cases respond favorably to growth modulation. The pretreatment parameters that correlated to a favorable response were low mandibular plane angle, low basal plane angle, and a high Jarabak ratio. In those cases that responded favorably, the changes seen were an increase in Co-Go (ramus height), decrease in overjet, increase in SNB, and increase in the Jarabak ratio.