We read with great interest the article in the May issue entitled “Comparative assessment of alignment efficiency and space closure of active and passive self-ligating vs conventional appliances in adolescents: A single-center randomized controlled trial” (Songra G, Clover M, Atack NE, Ewings P, Sherriff M, Sandy JR, Ireland AJ. Am J Orthod Dentofacial Orthop 2014;145:569-78).

The article answered many questions and must be appreciated for comparing the various bracket systems in a single trial. However, we were concerned about a few methodologies in the study. The authors have rightly concluded that the recall interval of 6 weeks for conventional brackets and 12 weeks for self-ligating brackets could have contributed to the findings that indicate a greater aligning time for self-ligation. Therefore, we were curious to know whether the “intention to treat” analysis and related statistics were efforts to overcome this issue.

Although the authors need to be appreciated for standardizing the archwire sequence and thereby eliminating a major variability, this standardization, we feel, would have done a disservice to the self-ligation systems, particularly the Damon Self Ligation system. We also feel that since “manufacturers’ recommendations” were followed for the recall time interval, a similar manufacturer recommendation for the archwire sequence for Damon could have been considered.

When the authors considered the rate of space closure, was anchorage loss, if any, evaluated? Also, were there any debonded or broken brackets? If yes, was this considered when the final results were being computed?

It also appears that there were 8 operators, and hence this could have also contributed to the results, since there would be an interobserver variability not only in deciding on the actual timing of stepping up to the next aligning archwire in the sequence followed, but also with the actual completion of the aligning stage. Lastly, there appears to be a typo in Table I, where the total of the Frankfort mandibular plane angles (low, average, and high) adds up to 105 when the original sample was only 100.