Objective: This study was conducted to evaluate the dento-skeletal effects of hard and soft chin cup in treatment of class III cases. Also, their effect on the skin of the chin was assessed.
Methods: The sample consisted of fifty five growing children and was randomly allocated into three groups. In group 1 (n=22) hard chin cup applying 300 g force/side was used, group 2 (n=22) soft chin cup was utilized, while in group 3 (n = 11) no treatment was performed. Lateral cephalograms were taken for all participants before and after 12 months of treatment. The skin of the chin was evaluated using Skin Irritation Index (SII). Cephalometric data was statistically analyzed using one-way ANOVA and Tukey test while Chi-square test was utilized to evaluate the SII.
Results: There were significant reduction in SNB, 1-MP angles and Ar-Go and an increase in the ANB, SN-MP angles, Wits appraisal and N-Me measurements in the treatment groups compared to control group (P ≤ 0.05). In addition, 1-MP angle was significantly decreased with soft chin cup than the hard chin cup (P ≤ 0.05). Erythema of the skin was the common effect for both chin cup type. There was no significant differences between hard and soft chin cup (X2 =2.59, P=0.28) although laceration was grater with hard chin cup.
Conclusions: Hard and soft chin cups are effective in treatment of class III malocclusions. Erythema of the chin skin was the main effect of both types and lacerations were greater with hard chin cup.