2021 Volume 9 Issue 1
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Reham Ibrahim El Gazzar1*, Ahmed Mohamed Hafez1, Marwa Sameh Shamaa1, Mohammad Hosam Eldeen Zaghloul1, Yasser Lotfy Abdelnaby1

1 Department of Orthodontics, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. [email protected]


Different methods have been introduced for acceleration of orthodontic tooth movement. Because it is less invasive with minimal side effects, Platelet rich plasma (PRP) is one of the most recently used techniques. To evaluate the effect of submucosal injection of PRP on maxillary canine retraction and to report any associated pain. Twenty patients were selected and randomly assigned in a split mouth trial designed to obtain PRP injection in one side (study side) while the other received no injection and served as a control. Before canine retraction, injection was done and not repeated again. After extraction, leveling and alignment; canine retraction was done on 0.017x0.025-inch stainless steel arch wire with closed coil spring from the canine hook to a mini-screw inserted between upper second premolar and first molar on both sides. The study duration was 4 months. Alginate impression was taken before canine retraction and every month for four months. Data was obtained from digitized models to measure the amount of canine retraction. Pain assessment was carried out by visual analogue scale (VAS). The canine retraction rate in the study side was faster than the control side with a statistically significant difference (P<0.05) in all the four months of the study duration. The total distance travelled by the canine was greater in the study side with a statistically significant difference (P=0.022). Higher pain levels were observed in the study side. Submucosal injection of PRP is a minimal invasive and safe approach for accelerating canine retraction and reducing overall treatment time.

Key words: Acceleration, Platelet rich plasma, Pharmacological approaches, Canine retraction.


Orthodontic remediation is considered one of the most time-consuming dental treatments [1-4]. The estimated duration of the orthodontic treatment using conventional orthodontics is 24 months which may vary according to the severity of the case, individual characteristics, and treatment plan [2], prolonged treatment has a lot of adversities including caries [5, 6], external root resorption [7, 8], periodontal diseases and patient burnout [9]. Many attempts have been made to shorten the duration of orthodontic treatment including surgical, physical, and biological approaches [10], but there is still a lot of uncertainty and unanswered questions about most of these technologies. Several investigations have estimated the impact of many biological materials on the rate of orthodontic tooth movements (OTM) such as prostaglandin [11-13], vitamin D [14, 15], vitamin C [16], and parathyroid hormone [17] demonstrating favorable results. However, the use of supplementary hormones or other allogenic products require frequent injection and can cause undue systemic effect [18]. One of the lately applied biological agents to increase the rate of OTM is PRP. PRP is an autologous concentration of human platelets in a small volume of plasma [18]. PRP contains a lot of α granules which contain a lot of autologous growth factors and cytokines. These growth factors and cytokines play a very important role in osteoblastic and osteoclastic activity stimulating the alveolar bone remolding process [19, 20]. Liou [21] reported that PRP can accelerate different types of tooth movement clinically. Rashid et al. [22] and Gulec et al. [23] reported a positive relationship between local injection of PRP and acceleration of OTM in animal studies. On the contrary Akbulut et al. [24] reported that PRP was not beneficial in accelerating OTM. Also, Timamy et al. [25] reported the short-term acceleration effect of PRP. As the effect of PRP is still controversial, further clinical studies have to be conducted to confirm the effectiveness of PRP on OTM acceleration. The purpose of the present trial was to evaluate the influence of submucosal injection of PRP on maxillary canine retraction and to record any related pain.

Materials and Methods

This trial is a split-mouth randomized clinical study with 1:1 allocation. The trial was carried out at Mansoura University and approved by the faculty of dentistry ethical committee (No. M08070519).

The sample size was calculated using G power version based on a type I error frequency of 5%. Taking into consideration the vitro studies done by Rashid et al. [22] and Gulec et al. [23], we assumed the effect size difference between groups to be large (0.4). The calculation using repeated Anova had revealed that 17 patients were needed. The sample was increased by 10% to 20 patients to guard against any dropout during the trial. A simple randomization procedure drawing lots was used to allocate the side of the maxilla for the PRP injection, while the opposing side will serve as the split-mouth control. All patients were recruited from subjects attending the orthodontic department, faculty of dentistry, Mansoura University.

The following inclusion characteristics were applied: (1) Both male and female subjects with class II division 1 malocclusion that require therapeutic extraction of the upper first premolars, (2) Age ranging from 16 to 22 years, (3) Good general and oral health, (4) Maximum anchorage required using a mini implant. The exclusion characteristics were: (1) Systemic diseases or medication that are probable to influence bone biology, (2) Evidence of root resorption, (3) Poor oral hygiene, (4) Previous orthodontic treatment.

All patients were acquainted with the study and the injection procedures and then they were invited to sign a consent.


All patients were treated using fixed orthodontic brackets MBT prescription; 0.022-inch slot brackets (Dentaurum, Germany). After initial leveling and alignment, each patient received two mini-screws (3M-Unitek, 1.8x8 mm) buccally on both sides between the upper second premolar and the upper first molar, 5 mm from the alveolar crest to be used as direct anchorage. The patients were referred for extraction of the upper first premolars within the same week of the mini-screw insertion. After that, leveling and alignment were completed until reaching 0.017x0.025-inch stainless steel wire to minimize binding and friction during canine retraction. The canine retraction was started after 6 months to ensure complete healing of the extraction socket [26].

PRP preparation and injection

PRP preparation was done under aseptic processing procedures by double spin technique as described by Liou [21]. A thirty ml from whole blood was drawn from the patient and was put in 3 PRP tubes (Golden VAC), each contains sodium citrate as an anticoagulant. The tubes were turned 180o upside down, shook, and mixed 6-8 times. The blood was first centrifuged under 1000 rpm for 12 minutes to separate red blood cells then pursued by a second centrifuge under 3000 rpm for 8 minutes to concentrate platelets. A high PRP concentration was obtained (5 times the concertation in whole blood) (Figure 1).



Figure 1. AZZOTA USA B-LSC-6K Centrifuge was applied producing high concentration PRP (5 times the concentration in the entire blood)

Before PRP injection, local anesthesia was used in the study side for pain control. Then 30 units of PRP have injected submucosally in six injection sites into the buccal and palatal mucosa distal to the canine. There are three sites of injection on the buccal mucosa. The first one was at 3 mm distal to the canine. The second one was marked 3 mm from the first one. And the third point of injection was 3 mm from the second one. The same procedure was conducted on the palatal surface (Figures 2 and 3). All the injections were volumetrically equal (5 units each area) and performed only before canine retraction and not repeated. No injection was done on the control side.

Figure 2. Submucosal injection of PRP buccally on the study side.