This study will compare the effect of standard-dose and micro-dose recombinant human bone morphogenetic protein-2 (rhBMP-2) with a placebo control on dental implant stability in the posterior mandible. Sixty patients requiring a single dental implant will be randomly assigned to one of three groups: standard-dose rhBMP-2, micro-dose rhBMP-2, or sterile saline only. Implant stability will be measured using Resonance Frequency Analysis at baseline, 2 weeks, 4 weeks, and 12 weeks. Marginal bone loss, peri-implant bone density, ectopic bone formation, and postoperative sequelae including swelling, pain, trismus, and soft tissue healing will also be evaluated during follow-up. The aim is to determine whether micro-dose rhBMP-2 can improve implant stability while reducing postoperative complications compared with the standard dose.

This prospective, double-blind, randomized controlled clinical trial is designed to evaluate the effect of locally applied recombinant human bone morphogenetic protein-2 (rhBMP-2) on peri-implant stability, marginal bone loss, peri-implant bone density, postoperative sequelae, and ectopic bone formation following dental implant placement in the posterior mandible.

Sixty systemically healthy adult patients requiring a single implant-supported restoration in the posterior mandible will be enrolled and randomly allocated in a 1:1:1 ratio into three parallel groups (20 participants per group). Group A will receive the standard dose of rhBMP-2 (0.1 mg), Group B will receive a micro-dose of rhBMP-2 (0.02 mg), and Group C will receive sterile saline as the placebo control. Randomization will be computer-generated, and an independent assistant will prepare identical coded syringes to maintain allocation concealment. Patients, the operating surgeon, the clinical outcome assessor, and the statistician will remain blinded until completion of the final statistical analysis.

All implants will be placed by the same surgeon using the MegaGen AnyRidge implant system following a standardized surgical protocol. The allocated solution will be delivered into the prepared implant osteotomy immediately before implant insertion. Healing abutments will be connected at the time of surgery to allow non-invasive longitudinal resonance frequency analysis without disturbing the peri-implant tissues.

The primary outcome is peri-implant stability measured using Resonance Frequency Analysis (Osstell Beacon) at baseline, 2 weeks, 4 weeks, and 12 weeks after implant placement. Secondary outcomes include marginal bone loss and peri-implant bone density assessed using standardized CBCT at baseline, 6 months, and 12 months. Postoperative sequelae (pain, facial swelling, trismus, and early soft tissue healing) will be evaluated on postoperative days 1, 3, and 7. Ectopic bone formation will be assessed radiographically during follow-up. Statistical analyses will follow the intention-to-treat principle using repeated-measures and between-group analyses with statistical significance set at P < 0.05.

Inclusion Criteria:

• Patients aged 20 to 55 years requiring a single dental implant for a single tooth missing in the posterior mandible (strictly limited to one implant per patient to prevent clustering effects and intra-subject correlation).

Patients must be systemically healthy or medically well-controlled, categorized as ASA I or ASA II according to the American Society of Anesthesiologists classification.

Surgical sites must exhibit D2 or D3 bone quality with adequate residual alveolar bone volume (minimum 6 mm width and 10 mm height).

Patients must maintain optimal oral hygiene, suitable for a prosthetically driven implant treatment workflow.

Exclusion Criteria:

• Patients presenting with uncontrolled systemic conditions (e.g., unmanaged diabetes mellitus, active osteoporosis).

A history of radiotherapy or chemotherapy in the maxillofacial region. Current heavy smoking habits (>10 cigarettes per day). Active and untreated periodontal disease. Pregnancy or lactation.

Individual participant data will not be shared to protect participant confidentiality.

Participants and postoperative care providers will be blinded to treatment allocation. Randomization codes will be concealed until completion of data analysis.