Queries regarding cephalometric effects of Twin-block and van Beek Headgear-Activator in the correction of Class II malocclusion

Regarding the article published by Kirtane et al in this issue (Kirtane RS, Wiltshire WA, Thiruvenkatachari B, Shah A, Bittencourt Dutra Dos Santos P, Henrique de Sa Leitao Pinheiro F. Cephalometric effects of Twin-block and van Beek Headgear-Activator in the correction of Class II malocclusion. Am J Orthod Dentofacial Orthop 2023;163:677-89 [Epub 2023 Jan 6]), we would first like to congratulate the authors on their interesting work; we also would like to raise a few queries. 1.van Beek Headgear-Activator (vBHGA) and Twin-block appliance differ in their mechanism of action on both jaws. Pertaining to which their indications depend on the patient’s morphology, including their lower anterior facial height, overbite, and growth pattern. 1 Dermaut L.R. van den Eynde F. de Pauw G. Skeletal and dento-alveolar changes as a result of headgear activator therapy related to different vertical growth patterns. Eur J Orthod. 1992; 14: 140-146 Crossref PubMed Scopus (34) Google Scholar However, information only about the ANB angle has been mentioned. Please elaborate more on the patient selection criteria for both appliances. 2.There is no mention of the saggital position of the maxilla, whether it was normal or protruded. Could the author describe why they advised headgear components in patients with vBHGA to restain the maxilla or retract it? It has been mentioned that SNA has been reduced by 1.59° in patients with vBHGA, which is a significant change. 3.According to the author, the cervical vertebral maturation (CVM) stage does not influence treatment effects, 2 O’Brien K. Wright J. Conboy F. Sanjie Y. Mandall N. Chadwick S. et al. Effectiveness of treatment for Class II malocclusion with the Herbst or Twin-block appliances: a randomized, controlled trial. Am J Orthod Dentofacial Orthop. 2003; 124: 128-137 Abstract Full Text Full Text PDF PubMed Scopus (176) Google Scholar so they enrolled patients in each CVM stage and formulated the postfunctional changes. However, there was no mention of the treatment effects in each CVM stage. Please mention whether the difference exists or not. 4.According to O’Brien et al, 2 O’Brien K. Wright J. Conboy F. Sanjie Y. Mandall N. Chadwick S. et al. Effectiveness of treatment for Class II malocclusion with the Herbst or Twin-block appliances: a randomized, controlled trial. Am J Orthod Dentofacial Orthop. 2003; 124: 128-137 Abstract Full Text Full Text PDF PubMed Scopus (176) Google Scholar occlusal results and skeletal discrepancy were better for girls than for boys in patients with Twin-block and Herbst appliance. However, the study has mentioned the gender-based distribution of the participants. Please add a note about the gender-based variation in the treatment changes. 5.No retention protocol was mentioned for patients undergoing treatment with the vBHGA appliance. 6.According to the article, the patients wore the Twin-block appliance full-time except during eating. The Twin-block is a patient-friendly appliance 3 Clark W. Design and management of Twin Blocks: reflections after 30 years of clinical use. J Orthod. 2010; 37: 209-216 Crossref PubMed Scopus (18) Google Scholar in which active contraction of muscles plays a more important role than passive tension. 4 Aggarwal P. Kharbanda O.P. Mathur R. Duggal R. Parkash H. Muscle response to the Twin-block appliance: an electromyographic study of the masseter and anterior temporal muscles. Am J Orthod Dentofacial Orthop. 1999; 116: 405-414 Abstract Full Text Full Text PDF PubMed Scopus (30) Google Scholar Then why were patients advised to remove the appliance during eating? Please explain. 7.In the Discussion section, it was mentioned that the Twin-block group experienced a slightly fewer increase in the lower anterior facial height, which could have been in response to the removable clip-overbite plate with an inclined plane worn in conjunction with fixed appliances. The T2 cephalogram was taken in the postfunctional phase, as mentioned. No cephalogram was taken in the retention phase, so the author has tried to justify the finding on the basis of the period for which the lateral cephalogram was not assessed during the study. Cephalometric effects of Twin-block and van Beek Headgear-Activator in the correction of Class II malocclusionAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 163Issue 5PreviewThe Twin-block (TB) and the van Beek Headgear-Activator (vBHGA) are indicated for patients with Class II malocclusion with a retrognathic mandible. Although the former is commonly prescribed for horizontally growing patients, the latter is often recommended for those growing vertically. This study aimed to compare the skeletal, dentoalveolar, and soft-tissue short-term effects of TB and vBHGA, taking growth patterns into account. Full-Text PDF Authors’ responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 163Issue 5PreviewThanks for taking the time to read our manuscript! Full-Text PDF