Measurement of Crestal Cortical Bone Thickness at Implant Site: A Cone Beam Computed Tomography Study

Dental implants have emerged as a new treatment modality for the majority of patients complaining of missing teeth. Bone quantity and bone quality are among various factors which ensure the longevity of dental implant in the patient's mouth. The assessment of cortical bone thickness of the outer layer and the cancellous bone density by cone beam computed tomography (CBCT) has proved beneficial for the patient. This study aimed at presurgical measurement of crestal bone thickness at various implant sites using CBCT images.

This study was conducted in the Department of Prosthodontics in the year 2015. It included 218 patients who wanted to replace missing teeth. Patients were subjected to CBCT scan using NewTom CBCT machine operating at 120 kVp and 5 mA with a resolution of 0.1 × 0.1 × 0.1 mm³. New Net Technologies (NNT) software with a slice thickness of 0.1 mm was used in this study. A total of 780 implant sites were identified on images of 218 patients. In all patients, the measurement of crestal bone thickness in the region of implant site was performed with NNT software. The buccolingual measurement of crestal bone was done in cross sections obtained after CBCT Results: Out of 218 patients, males were 110 and females were 108. The difference between gender was nonsignificant (p > 0.05). Out of 780 implant sites, 370 were in the maxilla and 410 were in mandible. The difference was nonsignificant (p > 0.05). Out of 780 implant sites, 210 were in anterior maxilla and 160 were in the posterior maxilla. Totally, 235 sites were in anterior mandible and 175 were in the posterior mandible. The distribution was nonsignificant (p = 0.15). The mean crestal bone thickness in anterior maxilla was 0.82 mm, in posterior maxilla was 0.76 mm, in anterior mandible was 1.08 mm, and in posterior mandible was 1.18 mm. The difference among regions was significant (p = 0.01).

The highest thickness of cortical bone was observed in posterior mandible followed by anterior mandible, anterior maxilla, and posterior maxilla. Thus, considering the less cortical thickness in the posterior maxillary region, the implant placement should be done with proper attention.

Dental implant is the need of the hour. It is beneficial to patients in terms of longer survival rates. With CBCT, all measurements, such as bone quality and quantity have become easy because of three-dimensional nature. This has proved to be beneficial in the analysis of cortical bone thickness as well as measuring the distance from anatomical structures.