Letters From Our Readers

To: Editor, The Angle Orthodontist

Re: Treatment effects produced by the Twin-block appliance vs the Forsus Fatigue Resistant Device in growing Class II patients. Giutini V, Vangelisti A, Masucci C, Efisio Defraia C, McNamara J, Franchi L. The Angle Orthodontist. 2015;85:784–789

We read with great interest the paper entitled “Treatment effects produced by the Twin-block appliance vs the Forsus Fatigue Resistant Device in growing Class II patients”. Results showed that both mechanisms of correction were effective but the Twin-block resulted in more skeletal effects while the Forsus (FRD) had more dentoalveolar changes, including mandibular incisor proclination.

The Twin-block and Forsus patients were treated in different practices but average treatment time in both groups was 2.3 years (T1 – T2). Also, both groups began treatment when they were considered “circumpubertal”. Because treatment sequencing is different for the two appliances, do you think that could have affected the skeletal vs dentoalveolar contributions to Class II correction that were observed? Twin-block may have induced more skeletal changes because it was used at the start of treatment when patients were more actively growing while the FRD group was undergoing only alignment during this earlier growth stage. Then, when FRD was used later in treatment, more patients may have been considered “postpubertal” so more dentoalveolar changes occurred, rather than mandibular growth. With the retrospective design, it would be difficult to control for these timing differences but do you think that the outcomes would have been different if the sequencing between Twin-block and FRD with fixed appliances had been the same in both groups?

Thank you for conducting this study that raises interesting questions to discuss. We look forward to your response.