Effect of Impression Techniques On Screw Loosening for Screw Retained Implant Supported Restorations Under Cyclic Loading: “An in-Vitro Study”

El Sayed, Ahmed Amr; Kheiralla, Lamia; Kamel, Mostafa Hussein

doi:10.21608/jfcr.2025.291746.1082

Effect of Impression Techniques On Screw Loosening for Screw Retained Implant Supported Restorations Under Cyclic Loading: “An in-Vitro Study”

Document Type : Original research articles

Authors

¹ Post Graduate Researcher, Fixed Prosthodontics Department, Faculty of Oral and Dental Medicine, Misr International University, Cairo, Egypt.

² Professor of Fixed Prosthodontics, Fixed Prosthodontics Department, Faculty of Oral and Dental Medicine, Cairo University, Egypt

³ Lecturer of Fixed Prosthodontics Conservative Dentistry Department, Fixed Prosthodontic Division, Faculty of Oral and Dental Medicine, Misr International University, Cairo, Egypt

10.21608/jfcr.2025.291746.1082

Abstract

Background: screw loosening is a common mechanical complication in dental implants. Ensuring stable connections between implant components is crucial for long term success of the treatment.
Aim: The purpose of this in-vitro study was to assess the screw loosening of two implants impression techniques (Conventional vs digital) by measuring the removal torque value (RTV) of screw abutment before and after subjecting the specimens to cyclic loading.
Materials and methods: twenty -four implant fixtures were placed in epoxy resin blocks. Implant fixtures were divided into two groups (n= 12); where half of the samples had open tray conventional impression technique for recording implant fixture position using transfer coping (group C), while the other half had digital impressions using scan bodies (group D). Then screwmentable zirconia crowns were fabricated for all the samples using CAD-CAM technique. The suprastructures were screwed with 30 Ncm tightening torque, then they were subjected to cyclic loading for 37500 cycles. A digital torque gauge was used to record the removal of torque values before and after cyclic loading. The removal torque loss ratio was calculated before and after cyclic loading and analyzed using the SPSS statistical analysis.
Results: For Group C, the post load removal torque values (22.15±0.77) (Ncm) had a statistically significant higher values than Group D (20.63±0.91) (Ncm).
Conclusion Within the limitations of this study, the results suggested that the screwmentable suprastructure fabricated from conventional impression technique showed a better screw stability than that fabricated from digital ones.

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