A radiographic evaluation of cervical bone loss associated with immediate and delayed implants placed for fixed restorations in edentulous jaws

Background: Placement of dental implants is considered a successful and predictable procedure. An important biological benefit is the preservation of bone height following implantation. The purpose of this study was to examine the cervical bone loss (CBL) and its correlation with implant characteristics and anatomic factors, 1 to 8 years post-implantation of immediate and delayed implants. Methods: A total of 381 implants (144 immediate and 237 delayed) were placed in 44 edentulous patients (53 jaws) for fixed ceramometal restoration from 1989 to 1996. The mean mesial and distal cervical bone resorption of each implant was measured using panoramic radiographs, by an objective examiner using a computerized scanner before second stage surgery and 1 to 8 years (mean 3.5 years) follow-up. The length of the implant served as an internal standard. The examiner had no prior information on the examined implants. Results: Total CBL was 0.78 ± 1.22 mm. There was a significant difference (P = 0.049) between CBL of immediate implants compared to delayed ones. Implants >13 mm showed a significantly (P <0.001) lower CBL than shorter implants. Hydroxyapatite-coated implants had a higher CBL (P <0.001) compared to commercially pure titanium implants (P <0.001). The CBL of maxillary implants was higher than mandibular implants (P <0.001). Step-wise multiple regression probability tests demonstrated that implant location followed by coating, length, and timing of placement were the most important parameters for implant success (R² = 0.102). Conclusion: Cervical bone loss around dental implants is influenced by location, coating, length, and implant timing.