Authors' response

Abstract

We thank our colleagues for their keen interest in our article. We agree that a mean wear time of 12 hours does not represent full-time wear. As such, we highlighted this as an outcome of the study and referred to “prescribed” full-time and part-time wear protocols throughout the article and in the conclusion section. Our aim was to compare the responses and compliance to varying wear instructions in a real-world scenario. Clearly, compliance was suboptimal in both groups. This finding is intuitive and resonates with a number of recent studies involving objective wear assessment with removable appliances.1Čirgić E. Kjellberg H. Hansen K. Lepp M. Adolescents’ experiences of using removable functional appliances.Orthod Craniofac Res. 2015; 18: 165-174Crossref PubMed Scopus (16) Google Scholar, 2Schäfer K. Ludwig B. Meyer-Gutknecht H. Schott T.C. Quantifying patient adherence during active orthodontic treatment with removable appliances using microelectronic wear-time documentation.Eur J Orthod. 2015; 37: 73-80Crossref PubMed Scopus (39) Google Scholar Although we all hope for diligent, full-time wear of removable orthodontic components, we have yet to meet the unicorn who actually does so. The sample size calculation was based on detecting a 2-mm difference between the 2 groups as a result of the intervention (not, as the writers intimate, on a total reduction in overjet values). We feel this level of difference between the 2 groups as a result of intervention would indeed be clinically relevant and significant. It was also suggested that there was a risk of contamination bias, because subjects were recruited from the same peer group. Although this is conceivable, we do not believe this to be likely, because recruitment and subsequent random allocation were done within a large department with a broad catchment area. Though we cannot exclude this possibility, it is highly unlikely that participants were derived from the same peer group. Special measures to mitigate potential contamination bias were therefore not deemed necessary. Finally, the writers refer to the use of the ANB angle as a measure of skeletal response and suggest the use of articulare gnathion. We did record articulare gnathion for completeness in relation to baseline data. We assessed the skeletal response inferentially using a combination of the ANB value, Pogonion-Sella vertical, and A-sella vertical, which are commonly used techniques for assessment of skeletal response. It is important that a finite number of key cephalometric outcomes be included in orthodontic research studies; an excessive number of outcomes can result in problems related to multiple hypotheses with associated likelihood of false positive outcomes. Moreover, interrelationships do exist between cephalometric variables. Like the writers, we do not believe that now is the time to rejoice; however, we do feel this research has shed new light on wear regimes and their associated effects. Coupled with the findings from our complementary qualitative study,3El-Huni A. Colonio Salazar F.B. Sharma P.K. Fleming P.S. Understanding factors influencing compliance with removable functional appliances: a qualitative study.Am J Orthod Dentofacial Orthop. 2019; 155: 173-181Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar we continue to advocate near full-time wear during Twin-block therapy. However, armed with the knowledge that removable wear regimes are effective, we now tend to taper the introduction of the appliance during the initial weeks to reduce imposition of the appliances. Moreover, where wear is not forthcoming and the onus of full-time wear is a barrier, we will now suggest graduating to a nights-only regime before considering alternative means of Class II correction. Overall, our findings represent an incremental gain in our appreciation of the effects of wear regimes and the impact of functional appliance therapy; however, as ever, further research is required to better understand this. Part-time vs full-time wear of Twin-block appliance: Can we rejoice?American Journal of Orthodontics and Dentofacial OrthopedicsVol. 156Issue 3PreviewWith great enthusiasm, we read the article comparing part-time (PT) and full-time (FT) wear protocols for the Twin-block appliance (Parekh J, Counihan K, Fleming PS, Pandis N, Sharma PK. Effectiveness of part-time vs full-time wear protocols of Twin-block appliance on dental and skeletal changes: A randomized controlled trial. Am J Orthod Dentofacial Orthop 2019;155:165-72). This was a much-awaited study for any clinician who treats Class II malocclusion with removable functional appliances. We thought the results of this research would be a “clinician's delight” and herald a paradigm shift in functional appliance wear time. Full-Text PDF