Problematic sample in the study of interception of palatally displaced canines. Author's response

We thank Professor Peck and the Editor for the op- portunity of discussion. Approaching this research, we considered it to be unethical not to treat patients at risk for ectopically erupting canines or potential resorp- tive situations, since resorption of the incisor roots caused by ectopic canines has been found in almost 50% of patients in studies based on 3-dimensional im- aging. It is, therefore, advisable to eliminate the contact between the incisor and the unerupted canine as early as possible to reduce the risk of such a serious complica- tion. Patients with palatally displaced canines and those centrally positioned in the alveolar crest were included in this study because the latter are associated with the highest incidence of root resorption. This might explain the high occurrence rate of bilateral displacement in the study sample. Irrespective of the anteroposterior position of the canine, the common characteristic was the risk for ectopic eruption or potentially resorptive situations, established by using widely accepted clinical and radiographic criteria based on 2-dimensional panoramic radiographs. Some overestimation might have occurred; however, taking into account the complications that might arise and the possibility to prevent them, we believed that it was preferable to overestimate rather than to underestimate. We agree that the ability to distinguish the physio- logic position of the unerupted canine from a position indicating a pathologic eruption pattern at the same age would be particularly relevant for clinicians. 4 But therein lies a problem: 3-dimensional imaging is elective in evaluating the position of the canine, and the costs (from an economic and, more importantly, a biologic point of view) are still prohibitive in many practices. This probably accounts for some diagnostic limit in pa- tient selection. In this situation, it is preferable to per- form deciduous extractions with at least 1 already accepted clinical and radiographic criterion, rather than underestimating the problem. Concerning Professor Peck’s statement that “the extraction of the maxillary deciduous canine alone is still the most prudent conservative interceptive standard of care,” we do not agree. The double extraction of decid- uous canines and first deciduous molars only anticipates a physiologic event; it is no more technically difficult, bi- ologically expensive, or traumatic compared with the single extraction of only the deciduous canine. More fa- vorable changes of the intrabony position of the canine resulted in our study from double vs single extractions, including greater uprighting of the canine’ s long axis and greater distal movement of its crown. These findings were corroborated in a further study conducted on a larger sample, which also highlighted (1) greater uprighting of the first premolar long axis (thus improving local conditions for uneventful eruption of the canine) and (2) greater parallelism between the roots of the canines and the adjacent lateral incisors (thus reducing the risk for iatrogenic root resorption on adjacent teeth). It is our opinion that these data, despite being obtained by means of “randomized sampling methods and multiple statistical manipulations of data,” can provide reliable information that is helpful in making a sound clinical decision.