Efficacy of Liquid Phase Concentrated Growth Factors as an Adjunct to EDTA in the Treatment of Recession Type 1 Defect With Free Gingival Graft

Gingival recession is defined by the American Academy of Periodontology, as the exposure of the root surface caused by an apical displacement of the gingival margin relative to the cementoenamel junction. While it seldom leads to tooth loss, gingival recession can contribute to several clinical issues, including root caries, cervical abrasion, dentinal hypersensitivity, and aesthetic concerns .

The etiology of gingival recession is not yet fully understood. Nevertheless, a variety of predisposing factors have been identified, including mechanical trauma, plaque accumulation, periodontal phenotype, tooth malposition, high frenum attachment, and orthodontic treatment. Clinical evidence suggests that gingival recession commonly develops in the presence of multiple interacting risk factors rather than as a result of a single causative factor.

Several classification systems for gingival recessions have been proposed in the literature, with the aim of creating specific categories related to diagnosis, prognosis, and treatment plan. The main classifications were the following: Sullivan \& Atkins (1968) ; Mlinek et al (1973) ; Miller (1985) ; Smith (1997) , Mahajan (2010) ; Cairo (2011) ; Kumar (2013) , Cortellini and Bissada (2018) 3and Chambrone and Avila-Ortiz (2021) .

Even though Miller's classification is still very popular, inherent drawbacks associated with the Miller's system have started to emerge, suggesting either a modification or replacement of the Miller's classification system with some of the more recent and updated classification systems.

Cairo et al., introduced a classification system of gingival recession using the level of interdental clinical attachment as an identification criterion. This system identified three recession types namely: recession type 1 (RT1) included defects without loss of interproximal attachment while recession type 2 (RT2) showed interproximal attachment loss .In recession type 3 (RT3), the interproximal attachment loss was more than the buccal site and may be associated with an interproximal intrabony defect .

Modern periodontal plastic surgery comprises a multitude of procedures to treat and prevent periodontal recessions. According to the suggestions of Miller and Harris , surgical coverage of periodontal recessions should achieve the goal to reestablish a complete root coverage with a sufficient width of keratinized gingiva (≥2 mm), an aesthetically acceptable result and a physiologic form of the gingiva.

Pedicle soft-tissue graft procedures used in the treatment of recession defects may basically be classified into advanced flap procedures (coronally repositioned flap, semilunar coronally repositioned flap), rotational flap procedures (laterally sliding flap, double papilla flap, oblique rotated flap), regenerative procedures (with barrier membrane or with the application of enamel matrix proteins) and free soft-tissue graft procedures.

The free gingival graft (FGG) is a well-established surgical technique that can be performed as either a single-stage or two-stage procedure for root coverage. Although subepithelial connective tissue grafts have demonstrated high effectiveness in treating Miller Class I and Class II gingival recessions, FGG remains advantageous in areas with insufficient attached gingiva and shallow vestibular depth. Its strengths lie in its simplicity, ability to treat multiple teeth simultaneously, ease of tissue management, and applicability in cases with limited adjacent keratinized gingiva. Furthermore, FGG offers some degree of root coverage through creeping attachment.

Attempts have been directed toward improving the success and predictability of FGG procedures. It has been shown that pathological alterations of exposed root surfaces may interfere with the establishment of new connective tissue attachment. Consequently, considerable attention has been given to root surface conditioning techniques aimed at creating a biologically favorable environment for cell adhesion, removing the smear layer, and enhancing the biocompatibility of the treated root surface. Various agents have been suggested including citric acid, tetracycline HCI,ethylenediaminetetraacetic acid (EDTA), phosphoric acid, enamel matrix proteins , and growth factors including, platelet-rich plasma, injectable Platelet- rich fibrin (I-PRF) and liquid phase of concentrated growth factors.

EDTA is a chelating agent that combines to calcium molecules from root surfaces removing them from the tooth surface . which appears to promote early cell and tissue colonization by providing a more biocompatible surface for cell and tissue attachment. Being independent on a low pH, therefore no any toxicological side effects. This eliminates the necrotizing effect on the surrounding periodontal tissues. The recommended concentration of EDTA should be somewhere between15 to 24% in order to obtain an acceptable smear removing and collagen exposing effect.

Biologic constructs, especially growth factors, have gained significant interest for their ability to enhance the proliferation and adhesion of cultured periodontal ligament (PDL) cells on periodontally affected root surfaces. These agents show considerable promise in clinical periodontics, offering both biological efficacy and potential economic benefits.

The two most important families of growth factors can be classified as: bone-derived growth factors, namely the bone morphogenic protein (BMPs) family, and the autologous blood-derived growth factors which are released upon platelet activation. Accordingly, autologous blood-derived growth factor e.g., Platelet rich plasma (PRP), platelet rich fibrin (PRF) and concentrated growth factors (CGF) could be used in the treatment of gingival recessions to accelerate wound healing and repair.

However, the early generations of platelets concentrate have not been used as a root surface conditioner due to lack of the liquid phase. In recent years, major developments and advancements have been made with the aim of developing a liquid formulation of PRF (injectable platelet-rich fibrin, (I-PRF). Furthermore, modifications to centrifugation tubes have further allowed for a working liquid-phase concentrated growth factors (LPCGF) that may be used as a periodontal root surface conditioner.

In vitro study, was conducted to assess the effectiveness of EDTA and/or LPCGF on periodontally diseased root surfaces through their effects on PDL cells and revealed that the combination of LPCGF, which contains abundant chemotactic factors, with EDTA could induce greater recruitment of PDL cells than EDTA alone, accelerating the periodontal healing process. Moreover, they showed that, the application of LPCGF alone did not remove the smear layer, and its effect was poorer than that of combined LPCGF and EDTA application. Therefore, the combined treatment for root surface treatment/root surface biological modification is more effective due to slow sustained release of growth factors from LPCG which promote cell growth for a long period of time.

Therefore, our clinical study was conducted to determine whether LPCGF has a valuable role in improving wound healing and recession coverage after free gingiva graft surgery for the management of Cairo type 1 gingival recession defects.