Materials and methods

Study design and setting

An institution-based study was conducted in the Department of Prosthodontics and Crown & Bridge, Regional Dental College, Guwahati, Assam, India, affiliated with Srimanta Sankaradeva University of Health Sciences, Guwahati. The study was approved by the Institutional Ethics Committee of the Regional Dental College, Guwahati (approval number: RDC/29/2011/Pt.-I/1746). The study was conducted from August 2024 to January 2026. The study included patients reporting to the Department of Prosthodontics and Crown & Bridge with partial edentulism in the posterior maxillary region who opted for implant-supported fixed prosthetic rehabilitation.

Before inclusion, all patients were informed about the purpose, nature, and design of the study. The implant placement procedure, radiographic assessments, possible surgical risks, expected benefits, postoperative instructions, and follow-up requirements were explained to each patient. Written informed consent was obtained from all participants before enrollment.

Study sample and grouping

A total of 20 subjects were included in the study and categorized into two groups according to the preoperative CBCT assessment of bone quality. Group 1 included 10 patients with D3 bone at the proposed posterior maxillary implant site, while Group 2 included 10 patients with D4 bone.

Inclusion criteria

Patients aged ≥18 years with partial edentulism requiring placement of at least one dental implant in the posterior maxilla were included in the study. Only patients with an edentulous period of at least three months following extraction were considered. The implant site was required to have D3 or D4 bone quality, a residual alveolar bone height of ≥12 mm from the nearest anatomical landmark to the crest (or 1-2 mm above the crest), and a minimum ridge width of 4 mm throughout the implant site length. Sites free from local infection, cystic lesions, or other pathological abnormalities were selected. All participants were required to provide informed consent and demonstrate willingness to undergo surgery, adhere to postoperative instructions, and attend follow-up visits.

Exclusion criteria

Patients with American Society of Anesthesiologists (ASA) physical status III or higher, pregnant or lactating women, and individuals with parafunctional habits such as bruxism or clenching were excluded. Chronic smokers or tobacco users, patients with traumatic occlusion, insufficient inter-arch space for prosthetic rehabilitation, active oral infection, untreated periodontal disease, or poor oral hygiene were also excluded. Additionally, any local or systemic condition that could compromise healing or implant success was considered an exclusion criterion. Patients unwilling to provide consent or unable to comply with the follow-up protocol were not included.

Preoperative assessment

A detailed case history was recorded for each patient, including demographic details, medical history, dental history, history of extraction, oral habits, and general clinical findings. A thorough intraoral examination was performed to assess the edentulous area, adjacent teeth, mucosal condition, oral hygiene status, and available prosthetic space. Preoperative CBCT was performed for diagnosis and treatment planning.

Bone quality was assessed using gray-scale values obtained from CBCT and expressed in Hounsfield units (HU). Alveolar ridge width and alveolar bone height were measured at the proposed implant site. Radiographic evaluation was performed using the Carestream CS 9000 3D imaging system, with a 4 × 4 cm field of view, 120 kVp, 6.3 mA, 0.18 × 0.18 × 0.18 mm voxel size, and an effective radiation dose of approximately 150 μSv. Standardized imaging parameters were maintained for all patients, and measurements were performed using Blue Sky Plan software (Figure 1).

Figure 1: Representative cone-beam computed tomography image showing assessment of peri-implant bone density and alveolar ridge width in the posterior maxilla at L1, L2, and L3 levels.L1 = at the crestal level; L2 = 5 mm above L1; L3 = 5 mm above L2

All radiographic measurements were performed by a single examiner using a standardized measurement protocol to minimize inter-examiner variability.

Surgical protocol

All implant placement procedures were performed under strict aseptic conditions. The operative site was prepared using routine sterilization and draping procedures. Local anesthesia was administered using 2% lignocaine with adrenaline 1:80,000. A mid-crestal incision with a vertical releasing incision was placed at the proposed implant site, followed by elevation of a full-thickness mucoperiosteal flap using Molt’s No. 9 periosteal elevator. Dentis System implants (4.0 × 10 mm), featuring a tapered root-form threaded design with an SLA surface, were used in all patients. All implants were inserted with a final insertion torque of 35 Ncm, following which cover screws were placed.

The implant osteotomy was prepared according to the osseodensification protocol using Densah burs. Osteotomy preparation was initiated using a pilot drill, followed by sequential use of Densah burs (2.0 mm, 2.5 mm, 3.0 mm, and 3.5 mm) in counterclockwise densifying mode. A pilot drill was used initially to establish the implant site, angulation, and depth. Sequential Densah burs were then used in a counterclockwise densifying mode at 800-1,500 rpm under copious irrigation. After completion of the osteotomy, endosseous root-form dental implants were placed. Postoperative care was provided according to routine institutional protocol, and patients were recalled for postoperative evaluation and radiographic follow-up (Figure 2).

Figure 2: Clinical sequence showing implant osteotomy preparation and implant placement using the osseodensification protocol.(A) Preoperative occlusal view. (B) Flap retraction for osteotomy. (C) Osteotomy with Densah bur. (D) Endosseous implant placement. (E) Primary closure after implant placement.

Prosthetic rehabilitation was performed after an uneventful healing period of four to five months.

Outcome assessment

The primary outcome variables were peri-implant bone density and alveolar ridge width. Peri-implant bone density was measured in Hounsfield units, while alveolar ridge width was measured in millimeters. Both parameters were evaluated at the following three levels: L1, representing the crestal level; L2, representing the mid-apical level; and L3, representing the apical level. Measurements were performed at the following three time intervals: preoperative, immediate postoperative, and four months postoperative. The mean of L1, L2, and L3 was calculated for both peri-implant bone density and alveolar ridge width.

Statistical analysis

Descriptive statistics were calculated as mean and standard deviation. Intergroup comparisons between D3 and D4 bone were performed using independent t-tests. Intragroup comparisons between different time intervals were performed using paired t-tests. Correlation analysis was performed to evaluate the relationship of age with peri-implant bone density and alveolar ridge width. Gender-based comparisons were performed to assess possible differences between male and female subjects. A p-value <0.05 was considered statistically significant.