The search strategy identified 185 titles and abstracts. From this we obtained 105 full reports for the review. Eight trials, based on data from 592 patients who presented with Class II Division 1 malocclusion, were included in the review.
Early treatment comparisons: Three trials, involving 432 participants, compared early treatment with a functional appliance with no treatment. There was a significant difference in final overjet of the treatment group compared with the control group of -4.04 mm (95% CI -7.47 to -0.6, Chi2 117.02, 2 df, P < 0.00001, I2 = 98.3%). There was a significant difference in ANB (-1.35 mm; 95% CI -2.57 to -0.14, Chi2 9.17, 2 df, P = 0.01, I2 = 78.2%) and change in ANB (-0.55; 95% CI -0.92 to -0.18, Chi2 5.71, 1 df, P = 0.06, I2 = 65.0%) between the treatment and control groups.
The comparison of the effect of treatment with headgear versus untreated control revealed that there was a small but significant effect of headgear treatment on overjet of -1.07 (95% CI -1.63 to -0.51, Chi2 0.05, 1 df, P = 0.82, I2 = 0%). Similarly, headgear resulted in a significant reduction in final ANB of -0.72 (95% CI -1.18 to -0.27, Chi2 0.34, 1 df, P = 0.56, I2 = 0%).
No significant differences, with respect to final overjet, ANB, or ANB change, were found between the effects of early treatment with headgear and the functional appliances.
Adolescent treatment (Phase II): At the end of all treatment we found that there were no significant differences in overjet, final ANB or PAR score between the children who had a course of early treatment, with headgear or a functional appliance, and those who had not received early treatment. Similarly, there were no significant differences in overjet, final ANB or PAR score between children who had received a course of early treatment with headgear or a functional appliance.
One trial found a significant reduction in overjet (-5.22 mm; 95% CI -6.51 to -3.93) and ANB (-2.27 degrees; 95% CI -3.22 to -1.31, Chi2 1.9, 1 df, P = 0.17, I2 = 47.3%) for adolescents receiving one-phase treatment with a functional appliance versus an untreated control.
A statistically significant reduction of ANB (-0.68 degrees; 95% CI -1.32 to -0.04, Chi2 0.56, 1 df, P = 0.46, I2 = 0%) with the Twin Block appliance when compared to other functional appliances. However, there was no significant effect of the type of appliance on the final overjet.