An Indirect Method to Measure Abutment Screw Preload: A Pilot Study Based on Micro-CT Scanning

Abstract

This study aimed to measure the preload in different implant platform geometries based on micro-CT images. External hexagon (EH) implants and Morse Tapered (MT) implants (n=5) were used for the preload measurement. The abutment screws were scanned in micro-CT to obtain their virtual models, which were used to record their initial length. The abutments were screwed on the implant with a 20 Ncm torque and the set composed by implant, abutment screw and abutment were taken to the micro-CT scanner to obtain virtual slices of the specimens. These slices allowed the measurement of screw lengths after torque application and based on the screw elongation. Preload values were calculated using the Hooke's Law. The preloads of both groups were compared by independent t-test. Removal torque of each specimen was recorded. To evaluate the accuracy of the micro-CT technique, three rods with known lengths were scanned and the length of their virtual model was measured and compared with the original length. One rod was scanned four times to evaluate the measuring method variation. There was no difference between groups for preload (EH = 461.6 N and MT = 477.4 N), but the EH group showed higher removal torque values (13.8 ± 4.7 against 8.2 ± 3.6 N cm for MT group). The micro-CT technique showed a variability of 0.053% and repeatability showed an error of 0.23 to 0.28%. Within the limitations of this study, there was no difference between external hexagon and Morse taper for preload. The method using micro-CT may be considered for preload calculation.

Systematic analysis of factors that cause loss of preload in dental implants

“…It is then followed by Ti alloys, surface-treated Ti, and pure Ti type of material [Table 2]. [14162831373840414244]…”

Marginal and internal fit of CAD/CAM frameworks in multiple implant‐supported restorations: Scanning and milling error analysis

“…A good noninvasive method to analyze ID is the CT . Research has used the aforementioned method for measuring the microgap on single, crown/abutment, implants . The present study is the first one using this methodology to analyze MD/ID on multiple implant‐supported suprastructures.…”

In vitro microtomography evaluation of the implant-abutment interface - Gap microtomography evaluation/ Avaliação da microtomografia in vitro da interface implante-pilar - Avaliação da microtomografia de Gap

“…The dental implants, all 8.0-mm-long, were placed in a cylindrical plastic ring filled with colorless self-curing JET acrylic resin (Classic™, Dental Articles -SP), aided by a dental surveyor to establish accuracy in both horizontal and vertical positions. The length of the implant inserted in the resin was 6 mm, with 2 mm of the implant outside the base (Rezende, et al, 2015;Tripodi, et al, 2012).…”

“…Several studies have used the 3D Micro-CT method to evaluate the micro-space at the implant-abutment interface (Abdelhamed, et al 2015;Scarano, et al 2016;Jorn, Kohorst, Besdo, Borschers, Stiesch, 2016;Mattheos, et al, 2017;Rezende, et al, 2015), as well as implant morphology, internal implant volume (Jorn, et al 2016), and preload (Maeda, Satoh, Sogo, 2006).…”