Effect of Dose-dependent Platelet Rich Fibrin(PRF)

Miller Class I Gingival Recessions (GR) have been treated by using Coronally Advanced Flap (CAF) with Platelet Rich Fibrin membrane (PRF membrane) or Connective Tissue Graft (CTG). The aim of this study was to evaluate the effect of different multiple layers of PRF membranes for the treatment of GR and compare the results with CTG procedure.

The Coronally Advanced Flap (CAF) has been used in combination with various techniques to increase the coverage and obtain the CRC. CAF+connective tissue graft and CAF+platelet concentrated graft are some of these procedures.

Because of a high success rate in the treatment of GR, CAF combined Connective Tissue Graft (CTG) procedure (bilaminar technique) is considered the gold standard for Miller Class I and II recession defects. According to recent studies CAF + CTG is described as a successful technique with a high CRC value and the percent root coverage achieved with this technique ranges from 79.9% to 89.6%. The advantage of this technique is the enhancement of keratinized tissue width which can be explained by the determination of surface epithelium characteristics of CTG. Moreover, there are disadvantages such as patient's discomfort because of postoperative pain or bleeding and second surgical area.

Therefore, the aim of this study was to evaluate the different doses of PRF membranes for the treatment of Miller Class I gingival recessions and compare with CTG procedure that is considered the gold standard.

MATERIALS AND METHODS In this study, sixty-three Miller Class I gingival recessions in twenty two subjects (10 males and 12 females, aged 21 to 52 years) were treated.

Study design This study was a randomized, controlled clinical trial, with a parallel design comparing different amount layers of PRF membranes and CTG for the treatment of Miller Class I gingival recessions. In the test group-1, 21 randomly selected GR were treated with 2 layers PRF membranes(2PRF)+CAF; in the test group-2, 21 randomly selected GR were treated with 4 layers PRF membranes (4PRF) +CAF and in the control group 21 randomly selected GR were treated with CTG+CAF.

Randomization Subjects were defined to one of the three groups with the use of computer-generated randomization scheme. Allocation concealment was obtained with number labeled opaque envelopes that were opened just before the surgery.

Sample size A software program‡ was used to calculate sample size. The power was calculated 85% when there was 20 gingival recession per each group, using the α value as 0.05.

Clinical measurements All clinical measurements were carried out by one of the examiners. Individual acrylic stents were prepared for all patients to take measurements on the constant points. The following clinical measurements were taken 1 week before surgery (baseline) and at the 1, 3 and 6 months follow up visits: 1) Recession Depth(RD) 2) Recession Width(RW) 3) Keratinized Tissue Height (KTH) 4) Plaque Index(PI), 5) Gingival Index(GI), 6) Probing Depth(PD), 7) Keratinized Tissue Thickness(KTT) 8) Clinical Attachment Level(CAL), 9) Root Coverage(RC). Post operative discomfort and bleeding were recorded using a visual analogue scale (VAS).

Surgical Procedure All surgical operations were performed by the same examiner. Patients received local anesthesia at recession sites and donor sites in the control group. Chlorhexidine mouthwash was performed for intraoral disinfection and antiseptic solution for extraoral disinfection.

Before the surgery, intravenous blood samples were collected from the test group patients. Samples were centrifuged and PRF clots were obtained according to the procedure described by Choukroun.14, 17 Two tubes of blood samples were collected and two layers of PRF membranes were prepared for patients in . Four tubes of blood samples were collected and four layers of PRF membranes were prepared for patients in 4PRF+CAF.

Following this, in test groups, a horizontal sulcular incision was designed at the buccal side of recession area at the level of CEJ. The incision was extended in the interdental area to be connecting CEJ. A split thickness flap was raised without vertical incision. The papillae were disepithelialized. The root was planned and hard accumulations were removed but no chemical root treatment was performed. In 2PRF+CAF group, two layers of stacked PRF membranes were positioned over the recession area at the level of CEJ . In 4PRF+CAF group, four layers of stacked PRF membranes were positioned over the recession area at the level of CEJ. Membranes were sutured to the recipient bed by a 6.0 resorbable suture at the level of CEJ. Split thickness flap was coronally advanced and sutured by a 5.0 resorbable suture.

Eligibility Criteria:
Inclusion Criteria:

1. Periodontally and systemically healthy patient, ≥ 18 years.
2. Miller Class I gingival recession at the buccal aspect of lower and upper incisors, canines or premolars.
3. The presence of ≥ 2 mm keratinized tissue apical to the recession.
4. The presence of identifiable cemento enamel junction (CEJ).
5. ≤ 2 mm probing depth (PD)

Exclusion Criteria:

1. Smoking
2. Pregnancy
3. Periodontal surgery in the past six months.
4. Caries, deep abrasion, restoration or pulpal pathology on the involved tooth.