Alumina implants: Ten clinical studies (eight prospective and two retrospective), with 395 patients and 967 implants, were included. Sample size ranged from 15 to 101 patients. The risk of bias in the included studies was moderate to high and the quality was medium to low. Follow-up periods ranged from two to 12 years. The survival or success rate ranged from 23 to 98% for single tooth replacement, partially dentate patients, and edentulous patients.
Zirconia implants: Three clinical studies (all retrospective), with 231 patients and 650 implants, were included. One study included 234 titanium implants. Sample size ranged from 36 to 124 patients. The risk of bias was high in all studies. Follow-up was one year in two studies and 1.8 years in the third. The survival or success rate ranged from 84 to 98%.