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

Thank you for giving us the chance to respond to Dr. Jain and colleagues' comments about our article. We appreciate the opportunity to clarify some aspects of our research further.

The study group received injectable platelet-rich fibrin (i-PRF) in the periodontal ligament space of the incisors two times: just before incisor retraction (T0) and at the second week (T2) of the retraction. The amount of i-PRF was standardized as 2 mL and was injected at the distopalatal side of the lateral incisors and palatal side of the central incisors (0.5 mL for each side).

The participants were not evaluated for their level of discomfort or pain on the day of injection with a numeric rating scale, and we did not observe any complaints of pain that required discontinuation of the injections.

Many researchers used the term “minimally invasive non-surgical technique” for injectable pharmaceutical agents (corticosteroid injections, platelet-rich plasma, Botox, dextrose injections) in the literature. Therefore, we described this technique as minimally invasive. There is no consensus for the application of i-PRF on tooth movement. In our previous study, results showed that, during the total follow-up period, the canine experienced nearly twice as much movement on the study side than the control side when i-PRF was applied twice with an interval of 2 weeks. Based on these results, we applied i-PRF twice with an interval of 2 weeks in this study. Patients were called every week to measure the amount of tooth movement and to see the effectiveness of i-PRF during a 1-month period. In routine practice, of course, the patient does not need to visit every week.

This study was carried out with measurements made during the retraction of the incisors after the canine distalization processes were completed. The measurements were bilaterally assessed as the distances between the lateral and canine teeth on the plaster models. It was important not to move the canine to ensure the reliability of the measurements. Posterior anchorage was reinforced using a transpalatal arch to prevent the movement of the canines.

All our patients completed the treatment process. We will also share their results; i-PRF application accelerated the tooth movement.