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Abstract
Purpose
This study evaluated the detorque values of screws in a multiple implant-supported superstructure using stone casts made with 2 different impression techniques.
Material and methods
A fully edentulous mandibular master model and a metal framework directly connected to four implants (Brånemark System®; Nobel Biocare AB) with a passive fit to each other were fabricated. Six experimental stone casts (Group 1) were made with 6 non-splinted impressions on a master cast and another 6 experimental casts (Group 2) were made with 6 acrylic resin splinted impressions. The detorque values of screws (TorqTite® GoldAdapt Abutment Screw; Nobel Biocare AB) were measured twice after the metal framework was fastened onto each experimental stone cast with 20 Ncm torque. Detorque values were analyzed using the mixed model with the fixed effect of screw and reading and the random effect of model for the repeated measured data at a .05 level of significance.
Results
The mean detorque values were 7.9 Ncm (Group 1) and 8.1 Ncm (Group 2), and the mean of minimum detorque values were 6.1 Ncm (Group 1) and 6.5 Ncm (Group 2). No statistically significant differences between 2 groups were found and no statistically significant differences among 4 screws were found for detorque values. No statistically significant differences between 2 groups were also found for minimum detorque values.
Conclusion
In a multiple external hexagon implant-supported prosthesis, no significant differences between 2 groups were found for detorque values and for minimum detorque values. There seems to be no significant differences in screw joint stability between 2 stone cast groups made with 2 different impression techniques. (J Korean Acad Prosthodont 2010;48:280-6)
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Fig. 1.
Master model with four external hexagon implant replicas made from a pickup impression of the superstructure to establish a passive fit relationship.
Table 1.
Means and SDs in parenthesis of detorque values (Unit: Ncm)
Table 2.
Type 3 tests of fixed effects for detorque values
| Effect | Num DF | Den DF | F value | P-value∗ |
|---|---|---|---|---|
| Group | 1 | 80 | 0.24 | .627 |
| Screw | 3 | 80 | 0.37 | .776 |
| Reading | 1 | 80 | 13.07 | .0005∗ |
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