Osteointegration of Tissue-Level Implants With Very Low Insertion Torque in Soft Bone: A Clinical Study on SLA Surface Treatment

Introduction: Evidence shows lower percentage of osteointegration when implants are placed without sufficient primary stability. The present work tested the hypothesis that implants unstable at insertion could achieve osteointegration with proper implant surface treatment. Materials and Methods: Eleven Straumann tissue-level implants with sandblasted, large-grit, acid-etched (SLA) surface treatment were placed in soft bone unfavorable to primary stability, as indicated by insertion torque lower than 10 N/cm and slight mobility on the application of a lateral load of 250 g. After 4 to 6 months of healing, a reverse torque of 35 Ncm was applied to assess osteointegration. Results: All implants appeared to be clinically osseointegrated and were successfully restored and loaded with fixed partial dentures or single crowns. After 28.5 months, all implants remained functional. Conclusions: Within the limitations of the low number of implants analyzed, it can be concluded that tissue-level implants with sand-blasted and acid-etched surface treatment can achieve osteointegration, even in the absence of primary stability.