Alveolar Ridge Preservation Versus Spontaneous Healing

Rationale: To determine the effect of alveolar ridge preservation (ARP) versus spontaneous healing (SH) in large buccal bone defects in the posterior mandible. Objective: To evaluate whether ARP using a xenograft (XG) (Cerabone plus) or an allograft (AG) (Maxgraft granules) covered by a membrane (Jason membrane) reduces the need for additional bone augmentation either prior to or during implant placement in the posterior mandible compared to spontaneous healing Study design: Prospective randomized clinical study with 10-year follow-up. Study population: Inclusion criteria: patients are 18 years or older and in need for extraction of a (pre)molar in the posterior mandible with at least one adjacent tooth and a buccal bone defect of \>50%. Exclusion criteria: the presence of active periodontal disease, uncontrolled diabetes mellitus, a history of or current use of chemotherapy or radiation in the head and neck area, history of or current use of medication related to osteonecrosis of the jaw, smoking (\> 5 cigarettes a day, disability (physical and/or mental), making the patient unable to maintain basic oral health or follow the study protocol, pregnancy (in case of pregnancy, the treatment is postponed until after the delivery). Intervention (if applicable): Atraumatic extraction of a (pre)molar in the posterior mandible will be performed. Patients will then be included based on the dimensions of the buccal bone defect (buccal bone defect of \>50%). 66 patients will be randomly divided in either the XG group, the AG group or the SH group (control). In the ARP groups (XG and AG), following tooth extraction, ARP will be performed using either a XG (Cerabone plus) or an AG (Maxgraft granules), both covered by a membrane (Jason membrane). In the control group, the alveolus will be left for spontaneous healing, following tooth extraction. After 4-6 months, a cone bean computed tomography (CBCT) scan will be performed to determine the possibility of implant placement with or without additional augmentation. Implant placement will be performed in all groups with or without guided bone regeneration (GBR). Main study parameters/endpoints: Frequency of additional augmentation at implant placement.

Extraction of the teeth in the posterior region of the mandible may be an indication for the placement of dental implants. However, after extraction of the teeth, the alveolar ridge undergoes changes due to resorption. Resorption is most pronounced on the buccal side and might complicate implant placement as is could lead to proximity issues with the inferior alveolaris nerve of the mandible. Alveolar ridge preservation (ARP) is commonly performed technique aimed at preserving available bone after tooth extraction. It facilitates delayed implant placement, reducing morbidity and providing optimal esthetic outcomes for implant placement. This procedure is performed using autogenous bone grafts, bone substitutes such as xenografts or allografts or a mixture of both. Also, membranes can be used to direct the growth of new bone. A thin buccal bone wall is an indicator for bone loss that may compromise the integrity of the buccal bone and lead to biologic and esthetic complications. When the buccal bone wall has a width of \< 1.5mm, it is considered an indication for ARP. ARP is found to be effective in reducing bone loss and facilitating implant placement after extraction in the anterior region and for multi-rooted sides. However, most available evidence including RCTs, involves patients with at least 50% of buccal bone intact. Consequently, it is uncertain whether the efficacy ARP is also applicable in situations involving damaged sockets (buccal bone loss \>50%).