Counter-torque of CeraOne and Esteticone abutments : a Strain-gauge evaluation

Objective: The counter-torque (CT) device is recommended to reduce or to eliminate the transmission of forces for the bone/implant interface during the screw tightening of prosthetic abutments. The objective of this in vitro study was to verify, by means of the strain gauge analysis, the microstrain around titanium implants during the screw tightening of prosthetic abutments (i.e. Cera One and Estheticone), with and without the use of the CT device. Methods: In a polyurethane block a cylindrical external hex implant was placed. The abutments were connected to the implants and the screws were tightened with an electronic torque-controlling device (Nobel Biocare Torque Controller) using torque of 30Ncm for Cera One and 20Ncm for the Esteticone abutments, with and without the CT device (n=5). During the screw tightening, perimplant microstrain (µε) was monitored with four strain gauges bonded around implant platform, in the upper surface of the polyurethane block. Results: Average microstrain values were calculated for the groups (CeraOne with CT: 222,06 µε and without CT: 446,01µε – Estheticone with CT: 134,32 µε and without CT: 327,63 µε), and data were submitted to statistical analysis. The differences between the techniques that used or not the CT device had statistical significance. Conclusion: In the group where the CT device was used, significant reduction in the transmission of force to the perimplant region occurred.