Study design
Nine consecutive patients between 18 and 78 years of age, with resorbed mandibular posterior ridges subsequent to tooth extraction who met the study inclusion criteria, were included. In total, 10 lateral ridge augmentation were performed using in situ hardening biphasic calcium phosphate graft material using the subperiosteal tunneling approach.
Inclusion criteria
Patients who presented with edentulous lateral mandible with at least the second premolar, and the first and second molars missing and horizontally atrophied alveolar crest that impairs prosthodontic rehabilitation were included in the study.
Exclusion criteria
Patients with severe alveolar ridge deficiencies (> 4 mm) as compared to the dentate segments, recent extractions (within 6 months), and patients with residual root stumps in the site, or periapical lesions, and infections or abscesses adjacent to prospective surgical sites were excluded from the study. Similarly, pregnant or lactating women, patients with known systemic diseases or metabolic disorders (e.g., HIV and diabetes) or those on medications known to be detrimental to bone healing (e.g., treatment with bisphosphonates and steroids), smokers or smokeless tobacco users, alcohol and psychotropic drug abusers, and patients with a history of malignant or other diseases treated with radiotherapy, or with chemotherapy within the last 5 years, were also excluded.
A signed, written informed consent was sought from each participant only after a full explanation had been given, a patient information leaflet offered, and time allowed for consideration. The right of the patient to refuse to participate in the clinical study without giving reasons was respected.
Surgical procedure
Before scheduling the surgery, a preoperative CBCT scan was performed to assess the ridge atrophy at the edentulous site and to decide if the patient fulfills the inclusion criteria. The surgical procedure was performed under local anesthesia with Lidocaine HCl 2% (Lignospan Special, Septodont, France) with adrenaline 1: 80,000. Figure 1a, b represents the initial CBCT and clinical presentation of one case.
A 5-mm vertical incision was made 8–10 mm away from the site to be augmented (Fig. 1c). The augmentation was performed with Tunnel Control instrument set (Hager & Meisinger, Neuss, Germany). A primary tunnel (pouch) was formed by detaching the periosteum from the underlying bone with the raspatorium supplied with the instrument set. Next, the cortical bone was partially removed in the tunnel, forming a furrow in the bone surface, exposing the underlying cancellous bone structures in the tunnel. This was achieved with a water-cooled round bur protected towards the soft-tissue component of the tunnel (supplied in the Tunnel Control instrument set). The bone graft substitute was prepared in the syringe according to the manufacturer’s instructions for use. The material was inserted into the tunnel (Fig. 1d), formed into the desired shape in situ, and pressed against the bone for 1–2 min by the surgeon. In contact with blood, the material hardened within this time span into a solid, porous body. Approximately, two to three applications of graft material 0.4 ml were used (1.2 ml per augmented site), as needed to restore the shape of the alveolar ridge. The wound was closed using an interrupted 4-0 vicryl suture. Figure 3a shows postoperative healing after 3 weeks of the grafting procedure.
CBCT scanning
Cone beam computer tomography (CBCT) scans were performed preoperatively and at 4 months post operatively to assess the gain in horizontal dimensions of the ridge. CBCT scanning was performed using a K9500 CBCT scanner (Kodak Dental Systems, Carestream Health Inc. Rochester, NY). For the present study, the medium mode with 15 × 9 cm field of view was used and the spatial resolution of each voxel was 0.2 mm3. Dental image processing was performed with interactive CT/CBCT image processing software (3D™ Cyber-Med Inc., Seoul, South Korea). The augmented volume was estimated by CBCT using the image processing software, graft outlines were marked manually on the scans. All augmented sites were treated for Dental implant placement. At the healing phase, the area was re-entered after reflection of a full thickness muco-periosteal flap (Fig. 2a). Dental implants were placed in the grafted area (Fig. 2b, c). In one patient, a core biopsy was obtained using a trephine drill (Komet Dental, Germany) in a bucco-lingual direction to harvest the tissue sample for histo-morphometric analysis. Figure 2d shows the final prosthetic rehabilitation done with individual crowns in the augmented sites.
Histological preparation and histomorphometric analysis
Histological sections were prepared from a bone core biopsy obtained in an oblique direction from the buccal cortex in one patient at the site of subsequent implant placement. Sample fixation for tissue samples were done in 4% buffered formaldehyde for at least 1 week at 4 °C before shipping to the histology lab. Qualitative, histomorphometric evaluation were performed of histological sections of two specimens from the same patient. Qualitative evaluation assessed bone formation (woven and lamellar bone), implant resorption, and presence of fibrous tissue and assessed cellular infiltration and type of cells, and finally, quantitative evaluation included histomorphometric measurements of percentage new bone, fibrous tissue, and remaining bone graft substitute using a special software program (Qwin, Quips, Leica, Glattbrugg, Switzerland). Figure 3a–e shows the results of the core biopsy. The graft material particles were tightly integrated into the newly formed bone. The area was also rich in osteoid tissue with osteoblasts and osteocytes. There was no inflammatory tissue present in the analyzed tissue, and the matrix was densely vascularized.
Statistics
Data were expressed as means ± standard deviations (SD). A non-parametric Wilcoxon rank-sum test was used to assess significance of intra-group longitudinal changes for ridge width changes as measured by CBCT analysis.
This study had been approved by IRB (Approval Number SHRAB/DS/2012).