Authors’ response

We appreciate the chance to respond to the comments on our article, “Evaluation of corticotomy-facilitated orthodontics and piezocision in rapid canine retraction,” published in April 2016.

All patients in our study were candidates for canine retraction and would benefit from the anticipated tooth acceleration regardless of their age. The mean ages were 20.7 and 19.8 years for the corticotomy and piezocision groups, respectively ( Table ). There was no significant difference between the mean ages to affect the treatment results. Each group had only 1 patient who was 15 years old.

Table
Means, standard deviations, and results of t tests for comparison of age between groups
Corticotomy group Piezocision group P value
Mean SD Mean SD
Age 20.7 3.4 19.8 2.7 0.52

We addressed our wire- and slot-size selections in the discussion section, mentioning that the 0.016 × 0.022-in wire size might lead to canine tipping. Yet, the low force used with the substantial time given by the reasonable acceleration of tooth movement was a great help for the canines to upright and prevent excessive tipping as shown in Table II in our article. The smaller wire size was preferred to avoid high friction.

To our knowledge, there is no conclusive evidence that tooth movement is faster in either the early or later stages. Yaffe et al reported that the regional acceleratory phenomenon (RAP) begins a few days after the surgery (ie, not immediately) and peaks between 1 and 2 months. This indicates that tooth movement might be greater in later stages than earlier. They also stated that it takes from 6 to 24 months to resolve completely. Although RAP is transient, orthodontic force prolongs the RAP ; thus the frequent orthodontic force application (biweekly). The lag phase at the start of any tooth movement—shortened in surgical patients yet still present—might be a reason for less tooth movement in the initial time interval.

The idea that surgical intervention improves anchorage was a target we aimed to prove or defeat. The subjects were intentionally mild to moderate anchorage patients as mentioned, to count the probable anchorage loss. Since no anchorage was used, we expected 50% movement of the first molar. The transmissibility of RAP is a possible reason to enhance molar movement as well. Unlike with other surgical modalities, we warned that the surgical interventions used in this study have no role in improving anchorage, and thus conventional means of anchorage should be used.

Using corticotomy on one side and piezocision on the other is no guarantee that both sides will close at the same time. In our study, we didn’t initiate the step after canine retraction until both canines were retracted to Class I relationships in order that we could use symmetric mechanics.

Delay of treatment was a question not answered before the study results were obtained. This design decreases biologic variability among groups because the patient is his own control. Using the contralateral side as a conventional control is a protocol previously used in the literature.

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Apr 4, 2017 | Posted by in Orthodontics | Comments Off on Authors’ response
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