Immediate vs. early loading of dental implants: 3-year results of a randomized controlled clinical trial.

OBJECTIVES The aim of the present study was to test whether or not immediately loaded implants exhibit the same survival rates as early loaded implants. MATERIAL AND METHODS Eleven patients with bilateral free end mandibles were randomly assigned to treatment either with immediately (test) or early loaded implants (control). Test implants received provisionals in occlusion on the day of surgery, control implants 6 weeks later. Parameters assessed included implant stability quotient (ISQ), plaque, prosthesis stability and radiographs at baseline (implant insertion), 1 and 3 years. The statistical analysis was performed by means of Student's paired t-test and Wilcoxon's signed-rank test. The level of significance was set at P<0.05. RESULTS After a mean observation period of 39.8 months (36.7-53.1), three test implants were lost in two patients resulting in a survival rate of 85% compared with 100% for control implants. At baseline, the mean marginal bone level was significantly higher at test implants (mean=0.36 mm, SD +/-0.5) compared with control implants (1.08+/-0.37 mm). For both test and control implants, the bone level significantly decreased from baseline to 3 years (test: 1.51+/-0.79 mm; control: 0.89+/-0.94 mm). The bone loss until 3 years was not significantly different between test and control group. There was no significant difference for ISQ both at test and control implants between baseline (test: 63.59+/-4.62 mm, control: 65.35+/-7.43 mm) and 3 years (test: 66.47+/-7.47 mm, control 68.80+/-8.75 mm). CONCLUSIONS Immediate loading was associated with a lower implant survival rate. Although the test implants were placed with increased sink depth compared with the control implants, the marginal bone levels were not different between test and control at 3 years.