A comparison of two different techniques for early correction of Class III malocclusion

Abstract

Objective: To compare the effectiveness of Reverse Twin-Block therapy (RTB) and protraction face mask treatment (PFM) with respect to an untreated control in the correction of developing Class III malocclusion. Materials and Methods: A retrospective comparative study of subjects treated cases with either PFM (n 5 9) or RTB (n 5 13) and untreated matched controls (n 5 10) was performed. Both the PFM and control group samples were derived from a previously conducted clinical trial, and the RTB group was formed of consecutively treated cases. The main outcome variables assessed were skeletal and dental changes. Lateral cephalograms were taken at the start and end of treatment or during the observation period. Analysis of variance was used to compare changes in cephalometric variables arising during the study period in the lateral group. Linear regression analysis and an unpaired t-test were used to determine the impacts of treatment duration and gender, respectively. Results: Significantly greater skeletal changes arose with PFM therapy than with RTB therapy or in the control group (SNA, SNB, and ANB; P , .001). The dentoalveolar effects of RTB therapy exceeded those of PFM treatment, with significantly more maxillary incisor proclination (P , .001) and mandibular incisor retroclination (P , .006) arising with treatment. Conclusions: Both appliances are capable of correction of Class III dental relationships; however, the relative skeletal and dental contributions differ. Skeletal effects, chiefly anterior maxillary translation, predominated with PFM therapy. The RTB appliance induced Class III correction, primarily as a result of dentoalveolar effects. (Angle Orthod. 2012;82:96-101.)

Comparison of double-plate appliance/facemask combination and facemask therapy in treating Class III malocclusions

“…In several FM studies, a backward rotation of the mandible and an increase in lower facial height were reported. 11,27 However, some studies 5,28 reported that the posterior/anterior face-height ratio remained unchanged; in accordance with this finding, a nonsignificant change was observed in the SN/GoGn angle. The significant decrease in overbite in the treatment groups might be due to maxillary incisor protrusion and changes in lower facial height.…”

“…Tortop et al 30 concluded that changes in upper incisors resulting from treatment with modified tandem traction bow appliance could be responsible for the overjet difference compared with FM treatment. Seehra et al 27 reported that both FM and reverse twin block therapies resulted in similar overjet changes. In molar relation, the significant increase was greater in the DPA-FM group than in the FM group.…”

“…20,21 In Class III malocclusion treatment with functional appliances, backward rotation associated with a reduction in mandibular growth was reported. [4][5][6]17,18,[22][23][24][25][26] Seehra et al 27 reported that FM therapy had a greater effect on SNB than reverse twin block therapy, indicating a greater downward and backward rotational effect.…”

Treatment of Class III Malocclusion with Reverse Twin Block in the Growing Child (Case Report)

“…If left untreated, Class III malocclusion in the growing children will become worse with age, presented by the growth of the mandible exceeding the growth of the maxilla [1,2,5]. This unfavourable growth can also occur late in adolescence or in early adulthood, especially in relation to mandibular prognathism.…”

“…This unfavourable growth can also occur late in adolescence or in early adulthood, especially in relation to mandibular prognathism. Hence, although in Class III cases that are successfully treated, there is still a risk thatthe Class III growth pattern may re-establish itself [1,5,6].…”