Purpose: To determine the significance of primary stability, as measured by insertion torque (IT) and/or implant stability quotient (ISQ), in achieving osseointegration of nonimmediately loaded implants. Materialsand Methods: Three electronic databases were searched. Studies were included if they measured IT and/ or ISQ at time of placement and reported survival for up to 1 year. For studies where at least one implant failed, a random effects meta-analysis was carried out for the odds of survival. Results: In total, 3,431 publications were screened, and 79 were accepted for analysis. These included 28 RCTs, 12 CCTs, 10 cohort studies, and 29 case series. Overall, 21 studies provided individual implant data for a total of 1,413 implants, and 7 studies were included for meta-analysis. A total of 264 implants were placed with ISQ < 60 and 249 with IT < 35. Survival of implants placed with ISQ < 60 and IT < 35 were 97.7% and 95.2%, respectively. Meta-analysis found no evidence that an ISQ ≥ 60 was less likely to fail compared to ISQ < 60 (OR 0.54, 95% CI 0.17 to 1.75, P = .31), or that an IT ≥ 35 resulted in higher odds of failure compared to IT < 35 (OR 0.82, 95% CI 0.13 to 5.40, P = .84). Conclusions: This study found no evidence to support that an IT ≥ 35 or ISQ ≥ 60 for nonimmediately loaded implants results in higher survival than those below these values.
