Table 2.

Details of platelet-rich concentrates.^a

	Study ID	Intervention	Preparation protocol	Application method	Sites	Dose	Application interval
1	Tehranchi 2018 [19]	L-PRF clot	2700 rpm, 12 min	L-PRF plugs were placed gently into sockets, and sutured using 4-0 Vicryl sutures	Extraction socket of premolars	Not recorded	only once immediately after premolar extraction (day 0)
2	El-Timamy 2020 [20]	PRP injection	Not recorded	Intraligamental injection	Middle, distobuccal and distopalatal areas of distal surface of canines, together with submucosal injections buccally and palatally	25 units	0, 21, 42 days
3	Pacheco 2020 [21]	L-PRF membrane	2700 rpm, 14 min	The experimental alveolus was preserved with L-PRF membranes and sutured with a 4–0 nylon suture	Alveoli after first premolars extractions	Not recorded	only once 15 days before retraction initiation
4	Çağlı Karcı 2021 [22]	PRF injection	800 rpm, 3 min	Submucosal injection	Buccal, palatal and distal surfaces of maxillary canine	0.7 mL	0, 4, 8 weeks
5	Erdur 2021 [23]	PRF injection	700 rpm, 3 min	Intraligamental injection	Distobuccal and distopalatal sides of canine tooth	4 mL	0, 2 weeks
6	Karakasli 2021 [24]	PRF injection	700 rpm, 3 min	Intraligamental injection	Periodontal ligament space of incisors	2–3 mL	0, 2 weeks
7	Zeitounlouian 2021 [25]	PRF injection	700 rpm, 3 min	Submucosal injection	Buccal and palatal sides through attached gingiva	3 mL	0, 1 month
8	Joy 2021 [26]	PRP injection	1000 rpm, 12 min	Submucosal injection	Attached buccal gingiva and lingual mucosa of canine and first premolar extraction site.	1 mL	Only once at same appointment as canine retraction initiation (day 0).
9	Angel 2022 [27]	PRP injection	Not recorded	Submucosal injection	Buccal, palatal and distal sites around canine.	1.8 mL	Only once at same appointment as canine retraction initiation (day 0).

^aL-PRF, leukocyte platelet-rich fibrin; PRF, platelet-rich fibrin; PRP, platelet-rich plasma.