Letter to the Editor

To: Editor, The Angle Orthodontist Re: The effect of platelet-rich fibrin (PRF) on maxillary incisor retraction rate. Kuter Karakasli, Emire A Erdur. The Angle Orthodontist. 2021; 91: 213–219.

Thank you for publishing this article on the effect of platelet-rich fibrin (PRF) on maxillary incisor retraction rate. We read it with great interest and have some questions for the authors:

1. In another study¹ published by the same authors, the site and technique of i-PRF (injectable platelet-rich fibrin) was discussed. However, the present study does not give details of the injection at the four incisors. Kindly provide details regarding site, technique, amount of i-PRF injected per site, and mechanism behind its distribution around the injected teeth.

2. Kindly provide input on the pain associated with these injections and whether any criteria was utilized to assess pain perception.

3. The paper describes this technique as minimally invasive but is it non-invasive to draw the patient's blood every 2 weeks for i-PRF preparation and is it justified to increase the frequency of patient visits to every 2 weeks, which is two to three times as frequent compared to routine visits?

4. It is unclear why temporary anchorage device placement was done after canine retraction, and why was posterior anchorage still reinforced using a transpalatal arch?

5. The study described the results of only 4 weeks of incisor retraction. Is it possible to generalize the results to complete treatment, which will last much longer?

We would really appreciate the authors' comments for better understanding of this interesting approach.