Although clinicians routinely aim to provide prosthesis with accurate fit on implants, a degree of prosthesis misfit is inevitable. This exploratory animal study evaluated the effects of framework vertical misfit and the timing of implant loading on implant position and screw loosening. Four implants were placed in healed ridges of each side of mandibles of 3 sheep. On the right side, 2 immediate frameworks were placed after 2 days. One framework was fitting, and the other one had a vertical gap of 0.5 mm on the distal implant. After 8 weeks (1 st review), the left side received 2 conventional frameworks with similar fit conditions to the right side. All the animals were euthanised after 8 weeks (2 nd review). At the 1 st and 2 nd reviews, implant level impressions were taken to measure the vertical displacement of distal implants, and the retaining screws loosening torque values were measured. The loosening torque values for the immediate fitting frameworks were considerably greater than the immediate misfitting frameworks. This was noticeable at the 1 st review. At the 2 nd review, the loosening torque values were comparable for the immediate fitting and misfitting frameworks. Vertical implant displacement was observed for all the misfitting frameworks. However, much more implant displacement occurred under immediate frameworks. Therefore, implant frameworks with vertical misfit in the present study were associated with less screw stability and more implant displacement. Retightening the retaining screws during the maturation of bone seemed to maintain the torque values.

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