Two groups, matched for age and gender, will be defined after block randomisation for smoking. The test group will receive titanium-zirconium implants and the control group titanium implants. For a power of 80% and for p < 0.05, (SD = 1.66 according to previous studies, estimates made from 1 mm difference in margin bone level between the groups), the size of the groups has been defined as 44 patients per group. The investigators anticipate a loss of approximately 10% and therefore, the investigators have increased each patient group to 48 individuals. The data collection is completed when the number of patients has been reached.