Small-diameter titanium Grade IV and titanium-zirconium implants in edentulous mandibles: three-year results from a double-blind, randomized controlled trial

ObjectiveThe aim of this study was to compare crestal bone-level changes, soft tissue parameters and implant success and survival between small-diameter implants made of titanium/zirconium (TiZr) alloy or of Grade IV titanium (Ti) in edentulous mandibles restored with removable overdentures. Materials and MethodsThis was a randomized, controlled, double-blind, split-mouth multicenter clinical trial. Patients with edentulous mandibles received two Straumann bone-level implants (diameter 3.3mm), one of Ti Grade IV (control) and one of TiZr (test), in the interforaminal region. Implants were loaded after 6-8weeks and removable Locator-retained overdentures were placed within 2weeks of loading. Modified plaque and sulcus bleeding indices, radiographic bone level, and implant survival and success were evaluated up to 36months. ResultsOf 91 treated patients, 75 completed the three-year follow-up. Three implants were lost (two control and one test implant). The survival rates were 98.7% and 97.3%, and the mean marginal bone level change was -0.780.75 and -0.60 +/- 0.71mm for TiZr and Ti Grade IV implants. Most patients had a plaque score of 0 or 1 (54% for test and 51.7% for control), and a sulcus bleeding score of 0 (46.1% for test and 44.9% for control). No significant differences were found between the two implant types for bone-level change, soft tissue parameters, survival and success. ConclusionsAfter 36months, similar outcomes were found between Ti Grade IV and TiZr implants. The results confirm that the results seen at 12months continue over time.