Objectives: It is difficult to detect a misfit or define the fitness of a framework clinically. This study was to compare differences in continuous torque measurements (CTM) during screw-tightening of a ²passive-fit² and a 60 µm ²misfit² frameworks. Methods: A metal framework of 4x5x24mm (WxHxL) was fabricated on a model with two Nobel Biocare multiunit abutment analogs separated by 16 mm. A passive-fit model (P model) was fabricated by connecting the framework to two multiunit abutments and implant analogs that were then embedded into a block of epoxy resin. A misfit model (M model) was fabricated as the P model except that we inserted a spacer of 60 µm, which was removed during testing, between the framework and one of the abutments. The framework was first placed on the models and one retaining screw of P model and the retaining screw on the fit abutment of M model was tightened to 10 N-cm. Then, with a Osseocare equipment, CTM (torque value during every rotating degree change) were taken during tightening of the screw on the other fit abutment of P model and the 60 µm misfit abutment of M model to 10 N-cm. Measurements from 15 screws were taken in each model. Comparisons of CTM were made by (1) observing the rotating degrees of screw between the initial rising torque and final 10 N-cm, and (2) calculating the area under the torque-rotating degree curve. Results: The rotating degrees between the initial torque and final 10 N-cm were significantly different between the fit (58± 5 degrees, mean± sd) and misfit (98± 7 degrees) framework (T-test, p<0.05). The areas under the torque-rotating degree curve were also significantly different between the fit (276± 47 N-cm·degree) and misfit (357± 26 N-cm·degree) framework (p<0.05). Conclusions: The data suggested that continuous torque measurements may be useful in differentiating the fitness of a framework.

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