Influence of the geometry of the screwdriver-screw connection on the reverse torque of UCLA screws.
| Autor: | Reis WL, Malheiros AS, Neves FD, Maia-Filho EM, Gonçalves LM, Bandeca MC, Tavarez RRJ |
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| Jazyk: | angličtina |
| Zdroj: | General dentistry [Gen Dent] 2021 Sep-Oct; Vol. 69 (5), pp. 62-66. |
| Abstrakt: | The aim of this study was to evaluate the influence of the geometry of the screwdriver-screw connection on the reverse torque of UCLA screws after repeated cycles of tightening and loosening in an implant-supported prosthesis. Thirty sets of external hex titanium implants, UCLA abutments, and UCLA abutment screws were divided into 3 experimental groups (n = 10). In the square group, the implant and UCLA abutment system were mounted in an upright position using a screw with a square screwdriver-screw connection. In the hexagonal group, the implant and UCLA abutment system were mounted in an upright position using a screw with a hexagonal screwdriver-screw connection. In the hexalobular group, the implant and UCLA abutment system were mounted at 70° using a dynamic UCLA abutment and screw with a hexalobular screwdriver-screw connection. Ten alternating torque-reverse torque cycles were applied to each screw using a screwdriver fixed at the end of a digital torque meter. The screws with a square connection resulted in less loss of reverse torque than the other types. Screws with a hexagonal connection showed a statistically significant loss of torque initially but remained constant for the remaining cycles. For the screws with a hexalobular connection, the loss of torque was greater, and substantial deformation of the plastic in the microstructure was noted. The screwdriver-screw connection geometry had a direct influence on the reverse torque of UCLA screws, and the initial reverse torque of the abutment screws with a square connection was greater than that of the hexagonal and hexalobular designs. Competing Interests: The authors report no conflict of interest pertaining to any of the products or companies discussed in this article. |
| Databáze: | MEDLINE |
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