As experience with osseointegrated implants has grown, greater use has been made of placement in the posterior jaw. To reduce the risk of implant failure and increase the ability of posterior implants to tolerate the occlusal forces, it is beneficial to create a wider base either by using wider (eg, 5-mm) implants or by placing two or even three standard implants at one site. In the present series, unpaired 5-mm Nobelpharma implants were placed in 38 sites in the mandible and 21 sites in the maxilla. All implants were uncovered and restored with ceramometal crowns, with follow-up ranging from 3 to 26 months (mean 16 months) postloading. Two implants in one patient failed and were replaced successfully at 14 months. At 20 sites, pairs of 5-mm implants were placed and restored, and with a loading period of 3 to 26 months (mean 14 months), all of these implants were successful. At 34 sites, a 5-mm implant was paired with a 3.75-mm or 4-mm implant. With a loading period of 3 to 24 months (mean 13 months), one implant 5 mm wide and 8 mm long failed and was replaced successfully at 13 months, and an implant 4 mm wide and 10 mm long failed and was not replaced. The failure rate for this group of implants therefore was 3%. Double 3.75-mm or 4-mm implants were placed at 149 sites in the mandible and 13 sites in the maxilla. All of these double-root implants were uncovered and restored with ceramometal crowns. With follow-up ranging from 4 to 78 months (mean 37 months) postloading, there were five implant failures in four patients, for a failure rate of 1.2%. The failure rate for all 5-mm implants was 2.3%, and that for all double implants was 1.6%. The use of either 5-mm or double implants necessitates changes in surgical technique, and both are highly dependent for their success on proper surgical execution.
Keywords: endosseous dental restoration, dental implantation