Vertical Deviation Caused by Tightening Torque on Implant Scan Body: An In Vitro Study

This study evaluated the effects of manipulator level (ML) on implant scan body (ISB) seating. It also investigated ISB vertical deviation with various levels of tightening torque.

In total, 10 standard acrylic resin models were prepared with the implant on the first molar site. ISBs were placed on the models by six operators with three MLs, manually and with a torque of 15 Ncm using an electronic torque driver. Digital scans were completed with an intraoral scan device. After superimposition in the software, ISB vertical deviation was compared between the 15 Ncm torque level and manual operation. One experienced operator then placed the ISB with different torque levels (20, 25, 30, and 35 Ncm) using an electronic torque driver. The ISB vertical deviation was also compared among torque levels. Vertical deviations within ML were analyzed using one-way analysis of variance (ANOVA). One-way repeated measures ANOVA was used to analyze the differences between torque levels (α = .05).

ISB vertical deviations differed among MLs (P < .01). Significant vertical deviations were observed between 20 and 30 Ncm (P < .01), 20 and 35 Ncm (P < .05), and 25 and 35 Ncm (P < .05). The largest estimated marginal mean was 13.5 ± 4.11 μm with a torque of 35 Ncm.

Significant differences in ISB vertical deviation were observed according to MLs and tightening torque levels. The amounts of those deviations did not exceed the previously described occlusal threshold.