The objective of this randomized controlled clinical trial was to evaluate the effects of particulate xenogeneic bone grafts associated with autogenous bone graft or Leukocyte-and-Platelet-Rich Fibrin (L-PRF) for horizontal alveolar ridge augmentation. Twenty-eight patients presenting edentulous regions and requiring horizontal bone augmentation prior to dental implant placement were included in this study and randomly divided into two groups according to the proposed guided bone regeneration (GBR) treatment.

Fourteen surgical sites corresponding to Group A received bone regeneration with particulate autogenous bone tissue associated with deproteinized bovine bone graft (Bio-Oss Small®; Geistlich AG, Wolhusen, Switzerland). In Group B, fourteen surgical sites were regenerated with deproteinized bovine bone graft (Bio-Oss Small®) associated with L-PRF. In both groups, the grafted region was protected by a collagen membrane (Bio-Gide® Compressed; Geistlich AG, Wolhusen, Switzerland) fixed to the buccal and palatal bone plates using titanium pins.

Cone-beam computed tomography (CBCT) scans were performed preoperatively, immediately after the GBR surgical procedure, after 8 months of GBR healing, and immediately after dental implant placement to measure linear and volumetric changes in the alveolar ridge. At the time of dental implant placement, after an average period of 8 months following the guided bone regeneration procedures, bone biopsies were taken from the grafted area for histological, histomorphometric, and micro-CT analysis.

After a period of 6 months, the dental implants were reopened to receive implant-supported prosthetic rehabilitation. Implant stability was assessed using resonance frequency analysis at the time of implant placement in the grafted area and after an average of 6 months during the reopening surgical stage. Patient pain perception following bone regeneration procedures was assessed using a visual analog scale. All obtained data were statistically analyzed.

Inclusion Criteria:

• a requirement for the placement of one to four dental implants exclusively in the maxilla;
• insufficient horizontal bone remaining for dental implant placement (maximum width of 4mm);
• sufficient vertical bone height for subsequent placement of dental implant(s).

Exclusion Criteria:

• any contraindication for dental implant placement;
• the need for vertical bone augmentation;
• inflammatory or autoimmune disease in the oral cavity;
• use of immunosuppressants, corticosteroids, or bisphosphonates;
• a history of malignancy in the past 5 years;
• smokers;
• patients reporting excessive alcohol consumption;
• decompensated systemic condition;
• uncontrolled periodontal disease;
• insulin-dependent diabetic patients;
• patients with blood-related diseases.