Letter to the Editor

To: Editor, The Angle Orthodontist

Re: Effect of injectable platelet-rich fibrin (i-PRF) on the rate of tooth movement: A randomized clinical trial. Emire Aybuke Erdur, Kuter Karakaslı, Elif Oncu, Bahadır Ozturk, Sema Hakkı. Angle Orthod. 2021;91:285-292.

We read this article with great interest. However, in the Materials and Methods section, it said that “movement of the canine was evaluated by measuring the distance between the midpoints of the vertical lines drawn from the incisal edge to the cervical line over the marginal ridge of the lateral and canine teeth on the dental cast”, which means that the movements and positions of both the lateral incisor and canine directly affected the accuracy of measurement of canine retraction. However, the authors say that “Canine distalization was conducted using Ni-Ti closed-coil springs connected from a miniscrew to a hook placed in front of the canine brackets”, as shown in Figure 1, which means that the incisors and canine may have been retracted together with an en mass retraction pattern. Thus, the lateral incisor was retracted along with the canine, making the measured distance of canine movement less than the actual value. Do you think it would have been better to measure canine movement relative to a more stable landmark, or that the method of retraction could have been achieved differently for this study?