Assessment of Dental Implant Stability Using Two Platelet-Rich Fibrin Protocols ( A Comparative Clinical Study )

Aims: The current study aimed to compare implant stability of dental implants covered with one of two platelet rich fibrin preparation protocols namely Standard-Platelet Rich Fibrin and Advanced-Platelet Rich Fibrin) using radiofrequency assessment. Materials and methods: A total of ten male patients with an age range of 28-51 years participated in this split-mouth clinical study. The patients were divided into two groups based on the platelet rich fibrin (PRF) protocol to be used with dental implant insertion into positive control (S-PRF) and study group (A-PRF). Each patient represented the two groups in which he received 2 dental implants; ten implants for each group (a total of 20 dental implants) of standard length and diameter in the posterior mandibular extraction sites of ipsilateral or contralateral side. In the positive control group, the standard PRF protocol was to be used to prepare the PRF clot. In the study group, the advanced PRF protocol was to be used to prepare the PRF clot. Both PRF membranes were to be instilled inside the osteotomy bed during dental fixture installation. Following the installation of dental implants; radiofrequency assessment using Osstell Mentor Device immediately after insertion, four, eight; twelve weeks post-operative as secondary outcomes were conducted. Results: When comparing ISQ means of dental implants between both group protocols, the Friedman test values of ISQ means showed no statistically significant difference between them at the immediate day of surgery, four weeks, eight weeks and twelve weeks post-surgery yet showed increased levels of ISQ at end of the trial. Conclusions: Both S-PRF and A-PRF, similarly enhanced and maintained dental implant stability hence maintain osseointegration (synergistic effect) throughout the period of study and as disclosed by ISQ values. The use of PRF in its current forms seems to be an accepted minimally invasive approach with good clinical results.


INTRODUCTION
Achieving a short and uneventful implant osseointegration period could make immediate or early loading of a dental implant more reasonable and predictable. Platelet-rich fibrin (PRF) is frequently used to accelerate wound healing. The activated platelets in the PRF clot secret growth factors, which in turn enhance cellular proliferation, collagen synthesis, and osteoid production (1) .
Platelet concentrates for topical use have evolved as surgical adjuncts or suspensions in the field of regenerative medicine. They are autologous blood extracts transplanted to an injured site to improve local healing. Improving healing is a constant issue in all surgical disciplines (2) .
Platelet Rich Fibrin (PRF), is a second-generation platelet concentrate developed by Choukroun et al. in 2000 in France (3) . Platelet -rich fibrin (PRF) is a simple, low cost and minimally invasive method to obtain a natural concentration of autologous growth factors that is widely used to accelerate soft and hard tissue healing, thus, PRF is used in different fields of medicine. Unlike its predecessor, platelet rich plasma (first generation), platelet rich fibrin is strictly an autologous fibrin matrix containing a large quantity of platelets and leukocytes with a simpler preparation technique that avoids artificial or exogenous biochemical modifications (4,5,6,7,8) . The PRF preparation protocol is a simple technique by which a 10 ml sample of blood is collected in a vacutainer glass or glass coated plastic tube and immediately centrifuged at 3000 rpm for 10 minutes. At the completion of the centrifuge cycle, three parts can be localized in the tube: the red blood cells at the bottom, a fibrin clot that represents the PRF in the middle, and the acellular plasma at the top. 4) To improve its quality and content, hence efficiency, two preparation protocols from the original one have been added and are currently being used:
The PRF can either be used as a membrane (S-PRF or A-PRF), liquid or injectable form (i-PRF), or can be cut in fragments, and applied either in standalone therapies; additive therapies; or used in combination therapies with other biomaterials (4,9,10) .
The current conducted study aimed to compare bone density means around dental implants using two platelet rich fibrin protocols at four scheduled intervals with first (day of surgery) day as a baseline for comparison with 4, 8 and 12 weeks.  Centrifugation was performed according to the following two protocols designed for the current study:

MATERIALS AND METHODS
1-Standard PRF: The centrifuge cycle is 3000 revolutions per minute (r.p.m) for 10 minutes. (4) 2-Advanced PRF: The centrifuge cycle is 1500 (r.p.m) for 14 minutes. (9) At the completion of the designated centrifugation cycle, the two tubes were removed and placed in a plastic rack to allow the formed clots to rest and mature for 10 minutes. After ten minutes, the caps of tubes are removed and each PRF clot was gently picked up using sterile tweezers and laid on the PRF collection box grid (Figure1 ). The red blood cell layer was gently scraped off from each clot using scissors and a compression tray was laid over the clots for 5 minutes. This will release exudates from the clot turning it into a membrane with uniform thickness ready to be used during surgery.

Surgical Procedure
The same surgical protocol was fol-

RESULTS
The total number of patients enrolled in the current study included ten     (Table 3).  (9,10) .Several researches have been recognized dealing with standard platelet rich fibrin (S-PRF) to enhance osseointegration around dental implant beds and were defined as study groups for the basis of comparison (12,13,14) and a positive control group in another (15) whom considered the dental implant with S-PRF as a positive control group and a study group using diode laser to evaluate the biostimulatory effect of Low Level laser treatment on dental implants in bilaterally missing mandibular posterior teeth. Advanced platelet rich fibrin (A-PRF), a new concept in PRF has also become a topic of interest (16) . To the scope of our knowledge, this was the first study carried Clark et al. (19) used A-PRF with freeze-dried bone allograft to improve alveolar bone osseiogenesis and stability of the inserted dental implants. Cabaro et al. (20) compared between standard and advanced rich fibrin according to quantity of growth factors released from the trapped leukocytes in the fibrin mesh and found that the A-PRF is the best candidate for hard and soft tissue repair. Caruana et al. (21) demon-