Tooth extraction is among the most common dental treatments. The procedure results in the formation of a bone defect. During the healing phase, the vertical and horizontal diameters of the alveolar ridge decrease, which has a negative impact on planned prosthetic or implantoprosthetic therapies.

The socket preservation technique involves filling the socket with an augmentation biomaterial to reduce vertical and horizontal alveolar atrophy. This prospective clinical study compares two biomaterials suitable for alveolar ridge preservation: xenogeneic versus allogeneic. Histological analysis and radiographic parameters related to the dimensions of the alveolar ridge and bone optical density are evaluated during a 180-day follow-up period.

Tooth extraction is among the most frequently conducted procedures in the field of dentistry. The immediate result of this procedure is the formation of a bone defect that becomes occupied by a blood clot. The healing process of the socket is complex and unfolds over several stages, extending for many months or even years. Throughout this duration, there is a noticeable decrease in both the vertical and horizontal dimensions of the alveolar ridge. This reduction in volume can negatively impact any planned prosthetic or implantoprosthetic treatment. One of the numerous factors that influence the healing of the alveolar ridge is the thickness of the buccal bone plate. Sockets that possess a thin buccal bone plate (less than 1mm) are particularly susceptible to dimensional changes during the healing phase.

The technique of socket preservation, which involves filling the socket with an augmentation biomaterial, mitigates alveolar atrophy. The biomaterial placed within the socket serves as a scaffold that aids in stabilizing and maturing the blood clot during the initial phases of healing, while also facilitating the development of new bone by osteoblasts in the subsequent stages.

A variety of materials can be utilized for socket preservation, including autogenous bone, allogeneic bone, xenogeneic bone, and alloplastic materials. Each of these materials possesses distinct properties, which include osteoconduction, osteoinduction, and osteogenesis.

Osteoconduction refers to the capacity of a material to create a framework for the development of new bone tissue. Osteoinduction denotes the capability of a biomaterial to encourage undifferentiated mesenchymal cells to transform into osteoblasts, thus promoting bone formation. Osteogenesis is defined as the ability of living cells within the augmentation material to produce new bone.

Xenografts are biological materials derived from animal sources that demonstrate solely osteoconductive properties. These grafts are created from bone that has been meticulously processed to eliminate its organic elements and minimize immunogenic responses, resulting in a mineral framework predominantly made up of hydroxyapatite. Although bovine-derived materials (e.g., Bio-Oss®) are the most frequently utilized, alternatives from various other species are also accessible.

Allogeneic bone grafts are sourced from either living donors or cadavers and are subjected to processing techniques such as freeze-drying (FDBA) or demineralization (DFDBA). These methods aim to eliminate immunogenic elements while retaining the mineral and collagen matrix. Freeze-dried bone allografts possess mainly osteoconductive properties, in contrast to demineralized freeze-dried bone allografts, which exhibit both osteoconductive and osteoinductive properties due to the exposure of bone morphogenetic proteins (BMPs) during the demineralization process. The removal of the mineral component, however, compromises the volumetric stability of the graft. To attain osteoinductive potential while preserving volumetric stability, a partial demineralization of the allograft can be executed, resulting in a material with intermediate characteristics (e.g., BioBank®).

This prospective, randomised comparative clinical investigation is designed to evaluate two biomaterials used in the socket preservation technique. Adult patients presenting with an unrestorable maxillary premolar or mandibular molar are screened for eligibility and randomly assigned to one of two groups according to the augmentation material, using Research Randomizer software (https://www.randomizer.org/).

In the experimental group, socket preservation is performed using an allogeneic material (BIOBank®, cortico-cancellous bone powder, 0.5 mm granules). In the control group, socket preservation is performed using a xenogeneic material (Geistlich Bio-Oss®, 0.25-1 mm granules). A collagen membrane (Geistlich Bio-Gide®) is used to cover the socket in all patients, and it is stabilized with nylon 4-0 sutures.

The dimensional alteration of the alveolar ridge and the optical density of the bone are measured by superimposing cone-beam computed tomography (CBCT) scans with a field of view (FOV) of 5 x 5 cm, taken 7-10 and 180 days after surgery. Histological analysis is performed on bone biopsies taken with a trephine during implant surgery. Both groups received standardised perioperative management, including socket debridement, pharmacotherapy and scheduled postoperative follow-up.

Inclusion Criteria:

• Maxillary premolar or mandibular molar unsuitable for restorative treatment
• Vestibular lamina width of less than 1 mm
• Age between 18 and 65 years
• Absence of vestibular lamina defects, such as fenestrations or dehiscences
• Ability and willingness to attend scheduled follow-up visits
• Provision of written informed consent

Exclusion Criteria:

• Alcoholism
• Nicotine addiction
• Immunosuppressive medications
• Systemic diseases that could affect the healing of soft or hard tissues
• Chemotherapy or radiation therapy to the head and neck region within the past 5 years
• Poor oral hygiene
• Extensive tooth loss

Patients are unaware of the type of biomaterial used during surgery. Radiographic and histological examinations are performed by trained, independent investigators who are not involved in the surgical procedures. The surgeon is not masked due to the nature of the surgical interventions.