It was with anticipation and interest that we read this article by the same group that had published similar data on a pilot study investigating the risk of root resorption associated with piezocision (Chan E, Dalci O, Petocz P, Papadopoulou AK, Darendeliler MA. Physical properties of root cementum: part 26. Effects of micro-osteoperforations on orthodontic root resorption: a microcomputed tomography study. Am J Orthod Dentofacial Orthop 2018; 153:204-13). We had previously raised some concerns about that pilot study and as a closing remark in their response to our commentary, the authors previewed yet-to-be published data that declared statistically significant root resorption in patients undergoing micro-osteoperforations (MOPs). We would like to take this opportunity to seek some clarification from the authors and provide some comments to help the specialty understand the limitations of these findings.
The use of a cantilever spring to produce exaggerated buccal tipping of what appears to be a well-positioned premolar against the buccal cortical plate is not a movement that we use in orthodontic treatment. Indeed, the authors not only investigated this atypical and clinically undesirable orthodontic movement, but they then extrapolated the data to support what might happen in conventional orthodontic movement when teeth move through the trabecular alveolar trough in the absence or presence of MOPs. Since conventional orthodontic movements associated with routine procedures such as space closure, alignment, and leveling use force vectors specifically designed to prevent the kind of pathology that Chan et al produced, we must ask why did they not simply use conventional force vectors in their experimental design? Did they try lower force levels and find no significant effect of MOP treatment on the roots? Are they asking critical readers of their work to accept that MOPs, rather than excessive force, are the major contributor to root resorption in their study subjects?
Iatrogenic damage was 1 concern that we raised in regard to their pilot study on piezocision, and it seems that the authors have taken heed of our concerns. They did state that “emphasis was placed on obtaining adequate interradicular space to permit the . . . placement of micro-osteoperforations with minimal risk of iatrogenic damage” and that “No evidence of iatrogenic trauma was observed in this study.” However, we believe that the authors could have been clearer about the evidence, or the lack thereof, in regard to iatrogenic damage. Was there standardization of the clinician(s) performing the procedure? How was it determined whether the crater formed was, indeed, a result of root resorption rather than iatrogenic damage from the procedure?
Furthermore, there was no mention of blinding in the study. Although we agree that it may not be feasible to have the samples blinded when the procedures are being performed, single blinding of the analysis could easily have been performed. No information was provided on blinding during the data analysis in this study. If this group’s previous study was indeed the pilot model for this study, then it would be a concern because in the pilot study, the same operator who did the orthodontic procedures also performed the extractions and the microcomputed tomography analyses. Without any mention of blinding, the risk of bias in the analysis of the data is inherent in the current study.
Lastly, the clinical significance of the study is questionable. The only measurements with statistical significance were the total resorption volume and resorption in the middle third, with the values of these differences being 0.169 mm 3 (SD, 0.181 mm 3 ) and 0.091 mm 3 (SD, 0.177 mm 3 ), respectively. Put into perspective, the clinical significance of 0.169 mm 3 of total resorption averages to only 0.042 mm 3 per root surface. The authors were correct to state that the “clinical significance of this is debatable,” yet they chose to highlight this 1 finding with self-admitted debatable clinical significance in both the conclusions and the abstract. Possible conclusions derived from the same data could have been “there was no statistical significance in root resorption when the sides of the control and experiment groups were compared with each other” or “of a total of 7 site-specific comparisons, there was statistical significance only between the vertical middle third (mean, 0.091 mm 3 ; SD, 0.177 mm 3 )” or “20% of the control group demonstrated more resorption than the experimental group.” With such intense focus on 1 statistically but clinically dubious result in light of all potential positive effects of the procedure (which the authors also stated), one cannot help but be reminded of the idiomatic expression of “throwing the baby out with the bath water.”
We are fervent supporters and producers of innovative approaches to improve orthodontic treatment. The recent uptick in new techniques, materials, and devices, each claiming to be the next best thing since sliced bread, obligates us and our colleagues who share our passion for orthodontic research to be vigilant for weak methodology, overstated conclusions, and outright negligence in research. The advent of accelerated orthodontic techniques serves as a case study in how we should carry out this obligation. There are many outstanding animal and human studies by researchers with strong basic and translational science backgrounds supporting the safe use of these techniques. Researchers focused on the negative aspects of accelerated tooth-movement techniques are welcomed in this quest if their motives are to produce the safest techniques possible. But they are equally obligated to ensure that their data and conclusions are accurate, not exaggerated or overstated. We believe that ongoing scientific and logical debate is good for our profession and ultimately for our patients. However, sensationalized fear mongering, unintended or otherwise, is counterproductive and detrimental to these efforts.