Assessment of Keratinized Gingiva With and Without PRF Application in Patients With Dental Implant

Clinical oral implant related research is facing many interesting challenges. One of them is to create and maintain stable soft and hard tissues around osseointegrated oral implants.

It was suggested in a classic study that a minimum of 2 mm of keratinized mucosa (KM) around natural teeth is necessary to maintain gingival health. The lack of a sufficient wide zone of KM has been investigated as a potential contributing factor for peri- implant disease and therefore might influence the long- term success of oral implants.

Various studies have found a negative influence of the absence of KM on plaque accumulation. Oral implants with a narrow zone of KM (\<2 mm) frequently exhibit significantly higher plaque scores than those with wider zones of KM. Even a subdivision can be made between KM and attached KM (AKM). A statistically significant higher plaque accumulation and gingival inflammation around implants in the groups with KM \<2 mm and AKM \<1 mm was observed. However, this could not be confirmed in another study.

Interestingly, the presence of an adequate band of KM adjacent to the implant seems to reduce inflammation, hyperplasia and recession of the marginal peri- implant soft tissues. Furthermore, it might facilitate restorative procedures, improve aesthetics and enable the patient to maintain an adequate oral hygiene without irritation or discomfort.

In particular, in the lower jaw, a scarce amount of KM can be regularly encountered. A reduced height of the alveolar process, due to crestal bone resorption, result in loss of KM due to the reduced distance between the bone crest and "genetically defined" position of the mucogingival line. Notably, in the posterior segments of the lower jaw, a narrow KM might be related to muscle pull, high frenulum attachments and a shallow vestibule.

Today, the golden standard to augment KM is a free gingival graft (FGG) harvested from the palate. The main problem with this technique is the morbidity for the patient as it involves a second surgical site. Reported problems following FGG procedure are pain, change in diet, paresthesia, herpetic lesion, mucocele, arteriovenous shunt and excessive bleeding.

To overcome this problem, different authors have proposed alternative techniques and materials to augment keratinized tissue around teeth and oral implants.

Various studies have substantiated the viability of platelet concentrates on enhancement of osseous and associated tissue healing and PRF is one of the recent innovations of various platelet concentrates.

Platelet- rich fibrin (PRF) is a 2nd generation platelet concentrate, which was introduced by Choukroun et al in 2001. It is obtained by a simple and inexpensive procedure that does not require biochemical blood handling. Its 3- dimensional fibrin network promotes neovascularization, accelerates wound closing and fast cicatricle tissue remodeling. Platelet concentrates are considered a source of autologous growth factors that promote cell migration and proliferation. Given that PRF is produced without using any additive, the fibrin polymerization occurs in a physiological way, resulting in a similar fibrin network as the one formed during natural healing.

Studies show a constant release of growth factors such as PDGF (platelet-derived growth factor) or TGF-b (transforming growth factor) for at least 1 week up to 28 days and proved its accelerating effect on the healing process.