Success and failure rates of cylinder implants in type IV bone.

It is well documented that implant success rates are much lower in Type IV bone than in Types I, II, and III. However, all of these studies have reported on the use of screw type implants. The present study demonstrates the efficacy of cylinder implant use in Type IV bone. A total of 513 cylinders were placed in Type IV bone and were followed for 0 to 60+ months in function. The absolute success rate was 95.7%. Of the 22 fixture failures encountered, 8 were discovered at the time of second stage surgery, 3 during the first year following uncovering, and 11 occurred after 24 to 36 months in function. A possible rationale for the higher success rate of cylinders as compared to that reported for screw type implants in Type IV bone is presented. Further well-controlled studies directly comparing various implant designs in a range of bony sites are needed to better understand and to fully document the differences suggested by the present study.