I would like to question the methodology used in the article, Treatment effects of bonded spurs associated with high-pull chincup therapy in the treatment of patients with anterior open bite (Cassis MA, de Almeida RR, Janson G, de Almeida-Pedrin RR, de Almeida MR. Am J Orthod Dentofacial Orthop 2012;142:487-93). The aim of this prospective study was to cephalometrically analyze the dentoalveolar and skeletal changes produced by bonded spurs associated with high-pull chincup therapy. The authors mentioned that the spurs might be an excellent treatment option to allow normal development of the anterior dentoalveolar region, since spurs prevent thumb or dummy sucking, tongue thrusting, and anterior tongue rest posture. But oral habits were not evaluated while selecting subjects for this study. How can the mere presence of an anterior open bite be an indication to use bonded spurs without considering its etiology?
Assuming that the etiology of the anterior open bite was considered, the best possible design for this study would have been to include 4 groups: group 1 (control, no treatment), group 2 (only bonded spurs), group 3 (only high-pull chincup therapy), and group 4 (high-pull chincup therapy and bonded spurs). This design would have allowed evaluating and comparing not only the individual therapeutic effects of bonded spurs and high-pull chincup therapy, but also the combined effect of high-pull chincup therapy and bonded spurs.
Alternatively, the authors could have included 3 groups: group 1 (control, no treatment), group 2 (only high-pull chincup therapy), and group 3 (high-pull chincup therapy and bonded spurs). This design would have allowed evaluating and comparing the therapeutic effects in a step-up manner—ie, no treatment followed by what happens when high-pull chincup therapy alone is used, followed by high-pull chincup therapy combined with bonded spurs.
The authors have shown that, during treatment, there were a significantly greater decrease of the gonial angle, an increase in overbite, palatal tipping of the maxillary incisors, and vertical dentoalveolar development of the maxillary and mandibular incisors in the treated group. Now the question is how much did the high-pull chincup therapy and the bonded spurs contribute individually in increasing the overbite of the treated patients? It looks as if both the high-pull chincup therapy and the bonded spurs have become confounding factors.
In the control group, spontaneous correction occurred in 4 of 30 subjects. Is it possible that spontaneous corrections might have occurred in the experimental group also, that would have been attributed to the therapeutic effect of bonded spurs? Spontaneous correction becomes a confounding factor here. This was not considered by the authors before concluding that correction of the open bite occurred in 86.7% of the patients. Failure in overbite correction occurred in 4 subjects in the treated group. So if one considers cases of spontaneous correction along with failed cases in the treated group, the evidence for the therapeutic effect of bonded spurs becomes weaker.