This randomized controlled trial evaluated whether grafting the peri-implant "jumping gap" with injectable β-tricalcium phosphate (β-TCP) improves outcomes after immediate implant placement in sites where the horizontal gap between the implant surface and the surrounding socket wall exceeds 2 mm. Sixteen patients (a total of 39 immediate implants in the maxillary anterior and premolar regions) were randomly allocated in a 1:1 ratio to a test group (peri-implant gap filled with injectable β-TCP) or a control group (no grafting). The patient was the unit of analysis. The primary outcome was implant stability, measured by resonance frequency analysis and expressed as the implant stability quotient (ISQ) at baseline, 3 months, and 6 months. The secondary outcome was peri-implant bone density, monitored on standardized digital periapical radiographs (baseline, 3, and 6 months) and quantified at 6 months by a single cone-beam computed tomography (CBCT) scan.

Design: single-center, prospective, parallel-group, randomized controlled trial with a 1:1 allocation ratio. Ethical approval was obtained from the Research Ethics Committee, Faculty of Dentistry, Suez Canal University (approval no. 682/2023), and all procedures were performed in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants.

Participants: patients aged 20-50 years requiring extraction of a non-restorable maxillary anterior or premolar root, with a peri-implant jumping gap greater than 2 mm at the implant site.

Interventions: after atraumatic extraction and prosthetically driven osteotomy preparation, implants were placed at the crestal level. In the test group the peri-implant gap was filled with injectable β-TCP; in the control group no grafting was performed.

Randomization and blinding: the allocation sequence was computer-generated by an investigator not involved in surgery, with concealment by sequentially numbered, opaque, sealed envelopes. Outcome assessors, including the radiographic bone-density readers, were blinded to group allocation.

Outcomes: the primary outcome was implant stability (ISQ) at baseline, 3, and 6 months. Secondary outcomes were peri-implant bone density on periapical radiographs (Digora grayscale, 0-255) and on a single 6-month CBCT (gray-value-derived HU-equivalent radiodensity), and implant survival. Analysis used independent-samples t tests for between-group and repeated-measures ANOVA for within-group comparisons (α = 0.05), with the patient as the unit of analysis.

Inclusion Criteria:

• Age 20 to 50 years
• Non-restorable maxillary anterior or premolar tooth requiring extraction and immediate implant placement
• Peri-implant jumping gap greater than 2 mm at the implant site
• Adequate inter-arch space
• Good patient compliance

Exclusion Criteria:

• • Systemic disease affecting healing

  • Smoking of more than 10 cigarettes per day
  • Parafunctional habits
  • Poor oral hygiene
  • Active periodontal disease

Single (Outcomes Assessor)