Peri-implant Tissue Changes Using Dual Zone Concept with Connective Tissue Graft Versus Concentrated Growth Factor

Maintaining the natural esthetic appearance, particularly in the esthetic zone, together with the volume and contour of the soft tissue in harmony with the surrounding teeth soft tissue, is believed to be critical. However, postponing implant placement until hard and soft tissues have fully healed usually necessitates additional surgical intervention steps, such as guided bone regeneration or ridge splitting, or implant placement in undesirable positions with a low esthetic appearance to overcome alveolar ridge resorption.

In clinical practice, immediate implant placement (IIP) in the esthetic zone has been regarded as an ongoing concern. Immediate implant placement (IIP) aims to minimize the duration of therapy overall, cost-effectiveness, and patient aesthetic expectations. However, the physician needs to be aware of potential risks and undesirable effects associated with this surgery, such as early implant loss and dimensional alterations in soft and hard tissues. Clinical research continues to advance to improve predictability and minimize the occurrence of undesirable consequences following IIP due to evolving patients\' esthetic demands and expectations.

Over the years, numerous surgical techniques have been proposed to preserve the soft and hard tissues in the esthetic zone. These techniques include proper 3D implant positioning, flapless approach, the addition of bone graft, the use of grafts containing growth factors such as concentrated growth factor (CGF) and platelet-rich fibrin (PRF) membranes, the application of connective tissue grafts (CTG), the socket shield technique, or the use of customized healing abutments. In order to offset the peri-implant tissue reduction, various treatments were also devised, including vestibular socket therapy, the dual-zone concept (DZ), and immediate dentoalveolar restoration.

From the above-mentioned approaches, Dual Zone technique was utilized in conjunction with CTG, and CGF graft were primarily advised for peri-implant soft tissue phenotypic preservation, stability, and health. The dual-zone (DZ) concept was developed to reduce the amount of buccal contour change at the extraction site while enhancing the thickness of the peri- implant soft tissues by filling the buccal gap with bone graft in two zones: the bone zone up to the crest of the socket bone and the soft tissue zone. To illustrate, graft particles are absorbed into tissues, increasing their thickness while also providing stability and maintaining soft tissue volume. As a result, the DZ concept aims to maintain the gingival contour while providing excellent soft tissue esthetics.

Connective tissue graft (CTG) and concentrated growth factor (CGF) graft are two commonly used materials for soft tissue augmentation in implant dentistry. CTG has a long history of success in improving soft tissue volume and quality around dental implants by forming a scaffold for cell migration and tissue regeneration. On the other hand, CGF, a newer autologous platelet concentrate rich in growth factors, has demonstrated promising results in stimulating tissue healing and regeneration, potentially outperforming standard graft materials.

To begin with, the success of utilizing CTG in covering exposed roots and increasing the width of the keratinized mucosa (WKM) prompted research into its usage in conjunction with immediate dental implants to improve their final esthetic effects. CTG is thought to be the gold standard for dimensional stability together with IIP in the esthetic zone. Furthermore, inserting CTG concurrently with IIP was claimed to reduce the likelihood of advanced mid-facial mucosal recession, prevent papillae loss, improve soft tissue contour, and reduce crestal bone resorption independent of tissue biotype. Other researches, however, argued that using CTG resulted in bone resorption and lost dimensional stability over time.

Platelets naturally produce Growth factors (GF) such as platelet-derived GF, Transforming GF (TGF)-β1 and β2 (TGF-β2), fibroblast GF, vascular endothelial GF, and insulin-like GF, which promote cell proliferation, matrix remodeling, and angiogenesis. Concentrated GF (CGF) is prepared by centrifuging venous blood, which concentrates platelets in a gel layer made up of a fibrin matrix rich in GFs and leukocytes. CGF operates by degranulating alpha granules in platelets, which play an important role in early wound healing. CGF has been shown to contain more GFs than other platelet-based preparations such as platelet rich fibrin (PRF) and platelet-rich plasma (PRP), and unlike PRP, CGF does not dissolve quickly after application. Furthermore, it was demonstrated that CGF may release GFs for at least 13 days.

CGF, first introduced by Sacco, has recently gained popularity. It is produced by centrifugation of venous blood, similar to PRF, but at a different speed (2400-2700 rpm) to separate cells in the venous blood, resulting in fibrin rich blocks that are much larger, denser, and richer in GF than common PRF. This demonstrates improved regeneration capacity and versatility when utilizing the fibrin-rich block. Furthermore, many studies showed that CGF has higher tensile strength, more growth factors, higher viscosity, and adhesive strength than PRF. As a result, surgeons can utilize CGF as a barrier membrane to speed up soft tissue healing or mix it with bone graft to expedite new bone growth.

Despite the growing interest in immediate dental implants and soft tissue augmentation techniques, limited comparative evidence exists regarding the efficacy of different grafting materials in the dual zone approach, particularly in the esthetic zone. Therefore, there is a need for well-designed randomized controlled clinical trials to evaluate the comparative effectiveness of CTG and CGF grafts in immediate dental implants using the dual zone technique.

This randomized clinical trial aims to address this gap in the literature by comparing the clinical and radiographic outcomes of immediate dental implants with dual zone technique using CTG versus CGF graft in the esthetic zone. By assessing parameters such as volumetric soft tissue alterations, pink esthetic score, clinical measurements, and radiographic bone dimensional changes, this study aims to provide evidence-based guidance for clinicians in selecting the most appropriate grafting material for achieving optimal esthetic outcomes in implant dentistry.

III. Research Question:

Are soft and hard tissue changes following immediate implant placement with dual zone concept and concentrated growth factor graft the same as dual zone concept and connective tissue graft on volumetric analysis, pink esthetic score, clinical, and radiographic measures at baseline, 6 months, and 1 year?

PICOTS Elements:

Patient/Problem :Patients with hopeless teeth requiring extraction in maxillary esthetic zone.

Intervention : Guided immediate implant placement with dual zone technique using concentrated growth factor graft Comparator : Guided immediate implant placement with dual zone technique using connective tissue graft Outcome: Volumetric analysis, Pink Esthetic Score (PES), clinical assessment and radiographic assessment. Time: Baseline and 6 months. Setting : Faculty of Dentistry, Ain Shams University.