Antibiotic Prophylaxis Versus Placebo in Alveolar Bone Grafting: A Randomized Controlled Trial

Alveolar bone grafting plays a central role in modern oral rehabilitation by preserving vertical and horizontal dimensions of the alveolar ridge following tooth extraction. The procedure is fundamental for optimizing future implant placement, reducing the need for additional regenerative surgeries, and improving long-term functional and esthetic outcomes. Despite its widespread use, postoperative management varies substantially among clinicians, particularly concerning the prescription of systemic antibiotic prophylaxis. Although antibiotics are often used empirically to prevent postoperative infection and graft failure, current scientific evidence remains inconclusive regarding their real benefit in healthy patients undergoing intraoral grafting under controlled aseptic conditions.

Antibiotic overprescription has important implications. Globally, antibiotic resistance is recognized as one of the most serious public health threats. Misuse of antibiotics in dentistry contributes significantly to this problem, especially when they are prescribed in situations where clinical benefit has not been firmly established. Additionally, unnecessary antibiotic use exposes patients to risks of adverse reactions, gastrointestinal disturbances, allergies, drug interactions, and increased treatment costs. In the specific context of alveolar bone grafts, the low incidence of postoperative infections reported in the literature raises questions about whether routine antibiotic prophylaxis is truly necessary.

This randomized, double-blind, placebo-controlled clinical trial was designed to rigorously evaluate whether postoperative amoxicillin provides measurable clinical, microbiological, or regenerative benefits compared with placebo in patients undergoing alveolar bone grafting using Plenum® OssHP, a synthetic biphasic bioceramic composed of hydroxyapatite and beta-tricalcium phosphate (HA/β-TCP; 70:30 ratio). The biomaterial is used in regenerative dentistry due to its osteoconductive properties and long-term volumetric stability. Its predictable behavior offers an ideal experimental environment to assess whether antibiotics influence early healing, infection rates, or the quality of regenerated bone.

Participants aged 18 years and older who require alveolar ridge preservation or augmentation with Plenum® Oss HP following tooth extraction will be recruited and screened according to the protocol approved by the Research Ethics Committee. After signing informed consent, eligible subjects will be randomly assigned in a 1:1 ratio to either the antibiotic group or the placebo group. Randomization will be stratified to reduce selection bias, and both participants and investigators will remain blinded throughout the study period. Individuals in the intervention group will receive amoxicillin 500 mg every 8 hours for 7 days, whereas the placebo group will receive identical capsules without active drug.

Surgical procedures will follow a standardized protocol, including atraumatic extraction when applicable, careful debridement of the alveolus, biomaterial placement, and tension-free flap closure. Postoperative care instructions and rescue medication protocols will be identical for all participants. Follow-up evaluations will occur at 7, 14, and 30 days, and again at 6 months during the re-entry procedure, allowing for multiple types of outcome assessment.

A comprehensive set of clinical, radiographic, histological, microbiological, proteomic, and metabolomic outcomes will be evaluated to understand the biological and clinical consequences of antibiotic use. The primary outcome is the incidence of postoperative infection at 7, 14, and 30 days. Infection will be clinically defined based on established diagnostic criteria including erythema, purulence, fever, increased pain, and delayed wound healing.

The secondary outcomes encompass a multidimensional assessment of healing. Radiographically, cone-beam computed tomography (CBCT) imaging will be obtained at baseline and at 6 months to evaluate bone volume gain, density, and mineralization patterns within the grafted region. These measurements provide insight into the structural maturation of the regenerated bone and allow quantitative comparison between groups.

Histomorphometric analysis will be performed using standardized biopsies collected at the time of implant placement or re-entry surgery. Samples will be processed and stained to quantify percentages of newly formed bone, residual biomaterial particles, and connective tissue. These indicators offer a precise understanding of the regenerative dynamics and the quality of bone formation influenced-or not-by antibiotic exposure.

Microbiological analysis will be carried out using sterile endodontic paper points placed in the surgical site at 7 and 14 days. Bacterial load will be quantified using established molecular or culture-based methods, enabling assessment of whether antibiotics modify early colonization patterns or microbial composition.

Beyond these measures, this study includes an innovative component: proteomic and metabolomic profiling of bone biopsy specimens. These high-throughput analyses provide a molecular-level understanding of tissue remodeling, inflammation, cellular metabolism, and bone regeneration pathways. Differences in protein expression profiles or metabolic signatures between antibiotic and placebo groups may reveal subtle biological effects not detectable through clinical or radiographic evaluation alone. This integrative biological approach may help identify biomarkers associated with bone healing and clarify mechanisms through which antibiotics could influence regenerative processes.

Patient-reported outcomes such as pain intensity, swelling, functional limitation, and overall treatment satisfaction will also be systematically recorded. Adverse events, including allergic reactions, gastrointestinal symptoms, or other complications, will be monitored to evaluate safety. By combining traditional clinical endpoints with advanced biological and imaging techniques, the study offers a comprehensive evaluation of healing trajectories following alveolar bone grafting.

The overarching goal of this trial is to determine whether postoperative antibiotic prophylaxis provides significant advantages over placebo in terms of infection control, bone regeneration quality, or patient comfort. If no measurable benefit is identified, the findings will support a reduction in unnecessary antibiotic use in dental regenerative procedures, contributing to antimicrobial stewardship and promoting safer, evidence-based clinical practice. Conversely, if antibiotics demonstrate clear advantages, their use can be better justified and applied selectively to patients who stand to benefit most.

Ultimately, this study is expected to generate high-quality evidence to inform clinical guidelines and optimize postoperative care in alveolar ridge preservation and augmentation procedures. By addressing an important knowledge gap, the trial seeks to improve patient safety, refine regenerative protocols, and contribute to global efforts against antibiotic overuse.

• Volumetric bone formation and mineral density assessed by CBCT [Time frame: Baseline and 6 months]
• Histomorphometric characteristics of regenerated bone [Time frame: 6 months]
• Bacterial load at grafted sites [Time frame: 7 and 14 days]
• Proteomic and metabolomic profile of regenerated bone tissue [Time frame: 6 months]