Comparative Study of the Crestal vs Subcrestal Placement of Dental Implants via Radiographic and Clinical Evaluation

The study aims at using the level/depth of implant placement (equicrestal or cretsal) as the key parameter in measuring the vertical crestal bone loss (CBL) mesially and distally, using periapical radiographs (IOPARs) taken at 1-, 3-, and 6-months interval, postprosthetic loading.

Patients (n = 40; 18-65 years), with edentulous space anteriorly or posteriorly, were randomly divided into two groups, namely, group I (equicrestal) and group II (subcrestal) with 20 patients in each group. Implants were placed at an edentulous site (delayed implants), after obtaining cone-beam computed tomography (CBCT) scans. Prosthetic loading (following osseointegration) was done within 3 months of implant placement. The patients were followed up and IOPAR were taken to measure CBL at 1-, 3-, and 6-months interval, postloading. The CBL between the two groups was compared using IOPARs. The data obtained was compiled and unpaired Student's t-test was done for statistical analysis.

After the statistical analysis of the data obtained during follow-up, CBL was measured radiographically. Mesial and distal vertical bone loss was charted and compared between the two groups. The mean bone loss on the mesial aspect for group I implants is 0.39 mm and for group II implants, it is 0.27 mm, 6 months postloading, determined radiographically.

Subcrestally placed implants are conducive to the overall oral rehabilitation, as it has been seen to preserve marginal peri-implant bone for longer durations than their equicrestally placed counterparts, within the limitations of the current study.

The study prospectively relates the level of implant shoulder with respect to alveolar crestal bone, postloading. Following radiographic comparison between the two groups, significant clinical findings indicated that better esthetics and stability were seen in the subcrestally placed implants. This proves that implant placement level directly influences crestal bone levels; hence, indirectly affects esthetics and function.