A 4-year prospective clinical and radiological study of maxillary dental implants supporting single-tooth crowns using early and delayed loading protocols

Background: Recent studies have showed that immediate/early loading of dental implants is a clinically feasible concept with results similar to those for standard two-stage procedures, especially in the mandible. However, there are only a few studies regarding the immediate/early loading of maxillary implants supporting single-tooth crowns. Purpose: The aim of this study was to compare the clinical and radiological outcomes of early- and delayed-loaded dental implants supporting single-tooth crowns in the maxilla. Materials and Methods: Twenty-nine patients were consecutively treated between 2000 and 2002 with 59 Branemark System MK III TiUnite implants ( Nobel Biocare AB, Goteborg, Sweden) in the maxilla. Two groups were formed according to the loading protocols. In the test group, definitive implant-supported single crowns were delivered to 19 patients 6 weeks after the implant placement. In the control group, definitive implant-supported single crowns were delivered to 10 patients 6 months after the implant placement. Clinical and radiographic parameters were recorded at baseline, 1 to 4 years. Implant stability measurements have only been performed at 4-year follow-up recall. Results: Overall, three implants were lost during the study period. Two implants were lost in the test group including 36 implants, which indicated a survival rate of 94.4%. One of the lost implants was replaced and then osseointegrated successfully. One implant was lost in the control group during the healing period, which indicated a survival rate of 95.7%. The average marginal bone loss was 1.11 mm for 56 implants after 4 years. There were no significant differences in marginal bone levels, insertion torque, and resonance frequency values between the two groups. Conclusion: The results of this study indicate that 6 weeks of early loading period for TiUnite-surface titanium implants in the maxilla is reliable and predictable for this patient population and may offer an alternative to the standard loading protocol.