Autogenous Dentin Graft for Alveolar Ridge Preservatio

Following tooth extraction, the alveolar ridge undergoes progressive dimensional changes, primarily due to bundle bone resorption, which may compromise the volume and quality of bone available for future implant placement. Alveolar ridge preservation (ARP) procedures aim to minimize this resorption through the use of various grafting materials.

This prospective, randomized, controlled clinical trial was conducted at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Ankara Yıldırım Beyazıt University. Eligible participants were systemically healthy individuals aged ≥18 years (ASA I-II) who required extraction of a radiographically non-infected tooth. Patients with acute infection at the extraction site, advanced systemic disease, use of medications affecting bone metabolism, smoking or alcohol consumption, or anticipated non-compliance with follow-up visits were excluded.

A total of 56 extraction sockets from nine patients (six women and three men; age range, 24-55 years) were randomly allocated into four groups: Control (spontaneous healing without grafting, n = 13), Dentin (grafted with autogenous dentin particles, n = 14), Dentin + PRF (grafted with autogenous dentin combined with leukocyte- and platelet-rich fibrin, n = 15), and FDBA (grafted with freeze-dried bone allograft, n = 14). All surgical procedures were performed by the same operator to eliminate inter-operator variability.

The sample size was calculated using G*Power version 3.1.9.6 (Universität Kiel, Germany), based on a repeated-measures ANOVA design, an effect size of 0.20, a statistical power of 80%, and an alpha level of 0.05. The analysis indicated that a minimum of 52 extraction sockets (13 per group) was required.

Autogenous dentin grafts were prepared immediately after extraction according to the method described by Binderman et al. Soft-tissue remnants, enamel, and cementum were removed from the extracted teeth using a tungsten carbide bur under water cooling. The cleaned teeth were processed using a Smart Dentin Grinder (KometaBio, Israel) to obtain particulate graft material with a particle size of 300-1200 µm. The particles were subsequently disinfected for 10 min in a solution containing 20% ethanol and 0.5 M NaOH and rinsed with a buffered saline solution to neutralize the pH before graft placement.

For the Dentin + PRF group, platelet-rich fibrin was prepared from 10 mL of venous blood collected in sterile tubes without anticoagulant and centrifuged at approximately 2700-3000 rpm for 10-12 min according to the Choukroun protocol. The resulting PRF clot was compressed into a membrane, cut into small fragments, and homogeneously mixed with the dentin particles before placement into the extraction sockets.

Full-thickness mucoperiosteal flaps were elevated as required in the Dentin and Dentin + PRF groups, and the graft materials were adapted to ensure close contact with the socket walls. In the FDBA group, the commercially available allograft was placed with minimal or no flap elevation. In the Control group, the extraction sockets were allowed to heal spontaneously through blood clot formation without graft placement or flap surgery. The flaps were closed using 3-0 silk sutures. In selected cases in which primary closure could not be achieved, a free gingival graft was used as a "socket seal." Postoperative care consisted of a standard antibiotic regimen (amoxicillin/clavulanic acid, 1000 mg twice daily for 7 days), an NSAID analgesic, and a chlorhexidine/benzydamine mouth rinse. Sutures were removed on postoperative day 10, and patients were followed clinically at monthly intervals.

Four months after grafting, at the time of dental implant placement, cylindrical bone-core biopsies were obtained from the treated alveolar ridge using a trephine bur. Specimens were fixed in 10% neutral buffered formalin, decalcified in 10% formic acid, and processed for routine histological embedding. Sections (5 µm thick) were stained with hematoxylin and eosin for histomorphometric evaluation of newly formed bone, connective tissue, vascularization, and residual graft particles.

Immunohistochemical staining for bone morphogenetic protein-2 (BMP-2) was performed following antigen retrieval. BMP-2 expression was quantified using a semi-quantitative HSCORE method combining staining intensity (0-3) and the percentage of positively stained cells. Five randomly selected fields per section were evaluated at ×40 magnification independently by two blinded observers.

Statistical analyses were performed using IBM SPSS Statistics version 21. The normality of continuous variables was assessed using the Shapiro-Wilk test. Normally distributed variables were analyzed using one-way ANOVA followed by Bonferroni post hoc comparisons, whereas non-normally distributed variables were analyzed using the Kruskal-Wallis test followed by Bonferroni-corrected Mann-Whitney U tests for pairwise comparisons. A p-value ≤ 0.05 was considered statistically significant.