Primary and Secondary Stability of Implants in Postextraction and Healed Sites: A Randomized Controlled Clinical Trial.

PURPOSE: This randomized clinical trial aimed to investigate the relationships between insertion torque, implant stability quotient (ISQ), and crestal bone loss (CBL) of implants placed in fresh or 12-week healed extraction sites. MATERIALS AND METHODS: Forty patients were randomly assigned to one of two groups and had one implant placed immediately (test group, n = 20) or 12 weeks after extraction (control group, n = 20) at premolar or molar sites. For all implants, insertion torque and ISQ scores at insertion and loading were recorded. Patients were followed for up to 12 months. RESULTS: Implant success was 100% in both groups. No differences were observed concerning both ISQ at insertion and ISQ at loading. A stronger correlation was detected between ISQ at insertion and insertion torque in the postextractive group (R = 0.83), than in the delayed group (R = 0.39), while ISQ at loading and insertion torque showed no correlation. CBL at 12 months was significantly different between test (0.68 +/- 0.43 mm) and control (0.40 +/- 0.26 mm, P = .02) groups. CONCLUSION: Implant placement timing (immediate or delayed) may affect correlation between insertion torque and ISQ at insertion with ISQ at loading. While insertion torque influences ISQ at insertion, it does not affect ISQ at loading because of successful osseointegration. Postextraction and delayed implants seem to have similar ISQ at insertion and at loading, but different CBL after 12 months of follow-up because of postextraction bone remodeling.