Efficacy of intralesional injections of platelet‐rich plasma in patients with oral lichen planus: A pilot randomized clinical trial

Abstract Objective To evaluate the clinical efficacy of intralesional platelet‐rich plasma (PRP) injections compared to intralesional triamcinolone acetonide (TA) injections in the treatment of erosive oral lichen planus (EOLP). Material and Methods Twenty patients with EOLP were assigned randomly to either PRP or TA group. Patients received weekly intralesional injections for 4 weeks, and then followed up for 3 months on regular visits every 2 weeks. Pain scores using numerical pain score and clinical score were recorded by a blinded assessor each visit for all patients and remission score at the end of the trial was recorded. Results Both groups showed significant improvement in the clinical parameters (pain and clinical score) “p = .001.” Regarding remission of the lesions, 80% of patients in the PRP group showed complete remission compared to 70% in the TA group. However, there is no statistical significance when comparing the two groups in pain score, clinical score, or remission. Conclusions PRP injections could be considered as an effective alternative single treatment modality for EOLP. The protocol for this study registered in Clinicaltrials.gov registry under the identifier number: NCT03293368.

swallowing. Patients with symptomatic OLP often require treatment to reduce signs and symptoms of the lesions (Thongprasom & Dhanuthai, 2008). Different treatment modalities for OLP have been documented, such as corticosteroids, laser, antioxidants, topical anesthetic agents, and many more, but still, no treatment modality has been proven yet to be the single effective measure for controlling or curing the disease (Lodi et al., 2005).
Corticosteroids are considered the first-choice pharmacological remedy for managing OLP lesions because of their anti-inflammatory and immunosuppressive properties. Intralesional injections of corticosteroids were also used in managing OLP and proved effective.
Although intralesional corticosteroids maintain a high concentration of the drug at the injected site, prolonged use is associated with many systemic adverse effects, such as bad taste, dryness of the mouth, candidal infection, mucosal atrophy, delayed wound healing, and in later stages, suppression of hypothalamus pituitary adrenal axis (Lee et al., 2013).
Due to the several side effects of the current treatments, there is a need to establish an effective and efficient treatment modality for erosive OLP with lesser or no adverse effects. Platelet-rich plasma (PRP) is concentrated plasma of the patient's blood that contains a high concentration of platelets along with increased growth factors (GFs). PRP is emerging as an increasingly demanding clinical application as an alternative source of GFs for several dental procedures and oral mucosal lesions (Dhillon et al., 2012).
Activated platelets release various GFs, such as platelet-derived GFs, transforming GF, fibroblast GF, and vascular endothelial GFs; these are the main contributing and leading factors for cell proliferation, differentiation, neoangiogenesis, toxins withdrawal, and cellular regeneration. PRP decreases the associated morbidity and promotes wound healing with anti-inflammatory action. On the other hand, no adverse effects had been linked to PRP application and because it is usually prepared using the patient's own blood it does not elicit any immunological or allergic reactions (Pietrzak & Eppley, 2005).
Intraoral applications of PRP and PRF have been investigated in many fields, such as sinus elevation and ridge preservation where healing time, postoperative complications, bone quality, and volume were tested. But the results were inconsistent and the cumulative evidence shows insignificant differences between PCs and other comparable interventions (Bae et al., 2011;Del Fabbro et al., 2014).
The rationale for conducting this study was to provide a safe alternative treatment for patients suffering from resistant erosive OLP, which had proved a promising regenerative potential in the management of several refractory skin and mucosal lesions.
The aim of the present study was to evaluate the clinical efficacy regarding pain score and ulcer size of intralesional injections of PRP versus intralesional triamcinolone acetonide (TA) in the management of patients with erosive oral lichen planus (EOLP).

| Study design and sitting
This pilot randomized controlled clinical trial was conducted at the faculty of dentistry, Cairo University, from September 2017 to December 2020.

| Ethical approval
The study protocol has been approved (n. 17-10-7) by the research ethics committee (reference for Faculty of Dentistry, Cairo University).

Inclusion criteria
Patients with an age range from 18 to 70, presenting with a clinical picture that suggests the diagnosis of erosive OLP; bilateral, more or less symmetrical erosive lesions with a lacelike network of slightly raised gray-white lesions (reticular pattern), and histopathological findings that confirms the diagnosis (liquefaction degeneration of the basal cell layer with irregular-saw teeth like rete pegs) are considered eligible for the study.

Exclusion criteria
Any patient suffering from systemic disorders, such as hematological diseases, severe cardiovascular diseases, or patients with platelet count <150,000/mm 3 ; Hgb <11 g/dl, pregnant or active breastfeeding females, patients who had a lesion(s) with dysplasia, and patients who received treatment with any drugs that could cause oral lichenoid reactions, or receiving therapy with topical treatment for OLP in the last 2 weeks or systemic treatment for OLP in the past 3 months, anticoagulants or immunosuppression drugs are excluded.

| Interventions
PRP was prepared at the oral medicine department clinic from autologous venous blood collected in the same visit according to Mostafa et al. (2013). In the control group, TA 40 mg/1 ml aqueous suspension (Synthecortin Ampoule; *Medical Union Pharmaceuticals MUP.; Egypt*) was used (Lee et al., 2013).
The patients in both groups had received intralesional injections once every week for 4 weeks. The injections in both groups were applied after a field block with Mepevicaine 3% *Alexandria Co.; Egypt* anesthetic without vasoconstrictor. An amount of 0.5 ml of each treatment was injected per 1 cm 2 of ulcerated mucosa using a 25-gauge needle.
After the fourth week of intralesional TA application in the control group, topical Miconazole oral gel was prescribed for 1 week three times per day.

| Primary outcome
The pain was self-assessed by the patient using an 11-point (0-10) numerical rating scale, in which (0 = no pain) and (10 = the worst possible pain) (Seymour, 1982 (Thongprasom et al., 1992), the measures were recorded using a periodontal probe measuring the highest length and width of the lesion giving an average area space as follows: Score 0 = no lesions, normal mucosa Score 1 = mild white striae, no erythematous area Score 2 = White striae with an atrophic area less than 1 cm 2 Score 3 = White striae with an atrophic area more than 1 cm 2 Score 4 = White striae with an erosive area less than 1 cm 2 Score 5 = White striae with an erosive area more than 1 cm 2 2. Remission time according to Conrotto et al. (2006), the measures were recorded using a binary scale ([yes/stable or no/not stable]: yes indicates signs score more than 1; no indicates signs score equals 1 or less).
The main investigator H. A. and the assessor who was blinded recorded outcomes before the treatment as baseline data and at the beginning of each visit using the previous scale and scores.

| Sample size
Based on a previous study by Xia et al. (2006), a total sample size of 8 (4 in each group) will have 90% power to detect a difference in the VAS means between the two groups using t-test with a 0.05 two-sided significance level. The number is increased to a total sample size of 10 to allow for the use of a nonparametric test. The sample was further increased to 20 (10 participants in each group) to allow dropout loss. Sample size estimation was performed by nQuery statistical package.

| Sequence generation
Simple randomization using computer-based sequence generation software was used after patients' consent of enrollment.

| Allocation concealment mechanism
This trial used no concealment, as the interventions cannot be blinded from the patients or the investigator (too obvious to know).

| Implementation
The main investigator H. A. was responsible for the sequence generation, allocation, and enrollment of the participants.

| Blinding
The assessor of outcomes was blinded; she was NOT involved in any step during patients' allocation or during treatment delivery.

| Statistical methods
The mean and standard deviation values were calculated for each group in each test. Data were explored for normality using Kolmogorov-Smirnov and Shapiro-Wilk tests, and showed nonparametric distribution. Mann-Whitney test was used to compare between two groups in nonrelated samples. Wilcoxon test was used to compare between two groups in related samples. The significance level was set at p ≤ .05. Statistical analysis was performed with IBM ® SPSS ® Statistics Version 20 for Windows.

| Participant timeline
A biopsy of the lesion was performed for histopathologic examination for the confirmation of the diagnosis of new undiagnosed patients.
Then, recruited patients were assigned to one of the groups (intervention or control), after that, all participants in the intervention group had provided a recent complete blood picture to confirm that their platelets count is over 150,000, and pretreatment records were obtained for the lesions. Then, each week the same treatment protocol for each group was followed for consecutive 4 weeks; in total four injections were injected for each participant. After the last injection, the patients were followed up for 1 week to obtain the endpoint measures. The main investigator H. A. and the assessor followed up with all participants every 2 weeks for 3 months from the last visit to report flare episodes of the disease.

| Recruitment
The patient's database from the department of oral medicine and periodontology was filtered by their condition; eligible subjects were HIJAZI ET AL. | 709 contacted to ask for a follow-up visit. Those who agreed to be enrolled in the trial were asked to sign an informed consent, and then all participants were allocated randomly to either study group according to the computer-generated sequence.
The present study included 20 patients divided into two groups (10 in each group) suffering from EOLP, with the age range 24-65 years. Group (A) received intralesional PRP injections, while Group (B) received intralesional TA injections. Both treatments were administered once a week for four consecutive weeks. Photographs for the oral lesions, numerical pain score, and measuring of ulcer size were registered at baseline and at every visit after. The patients were followed up after treatment every 2 weeks for 3 months. The remission of the clinical outcomes was recorded at the end of the follow-up period.
Regarding mean age and gender distribution, there was no statistically significant difference between Group (A) and Group (B) where (p = .098). Mean age distribution in groups is shown in Table 1.

| DISCUSSION
Since OLP is a chronic disease, a complete cure is very difficult to achieve. Topical steroids are the mainstay of palliative therapy of symptomatic OLP. Due to the lack of strong evidence to support the single usage of any treatment for symptomatic OLP lesions, alternative remedies are frequently considered. With inconsistent therapeutic efficacies, many drugs and interventions have been investigated in symptomatic OLP with an urge to get more tolerable and safe treatment (Thongprasom et al., 2013).  are believed to mimic the physiological healing process through nuclear factor-kappa beta (NF-κβ) suppression (Chakravdhanula et al., 2016).

T A B L E 1 Age distribution among groups
All participants in the present study were free from any systemic disease that compromise the diagnosis of idiopathic OLP, nor taking drugs that affected platelet function. The patients had complete blood picture at baseline. Only patients with platelet counts ≥150,000/µl were included in the study. One of the main factors affecting platelets number in PRP is baseline platelets count in the whole blood (Andrade et al., 2008).
The response to PRP injections was variable among participants in the present study, which required the increase of treatment peri- Pain reduction in EOLP patients after intralesional PRP or i-PRF treatment was significant after 2 months (Bennardo et al., 2021;Sethi Ahuja et al., 2020) and 3 months of follow-up (Sobhy et al., 2020). Also, these results were similar to Loré et al. (2016) and Merigo et al. (2018) where they had reported significant symptoms reduction after 8 weeks of topical PRP application in erosive OLP, despite different frequencies of application (weekly and daily application, respectively) they showed the efficacy of PRP treatment for erosive OLP.
Regarding the clinical scores in each group at the end of the trial, there was no statistical difference between the two groups. However, a significant statistical difference was observed in clinical score between

| Study limitations
The small sample size and relatively short follow-up period are the main limitations of the current pilot study. Moreover, challenges in standardization of baseline measurements as lesion site, size, and pain score were also found during patients' recruitment. These limitations may have affected the overall estimation of the PRP injections healing effect.

| CONCLUSIONS
Based on the findings of this study it can be concluded that intralesional

CONFLICT OF INTERESTS
The authors declare no conflict of interest.

AUTHOR CONTRIBUTIONS
W. Ahmed and S. Gaafar designed and supervised the study.
A. Hijazi conducted sample recruitment, treatment delivery, data collection, and results analysis. All authors read and approved the final manuscript.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.