Retrievability of Fractured Abutment Screws in Dental Implants Using Three Removal Techniques: An In Vitro Pilot Study

TL;DR

This study compares three methods for removing broken screws in dental implants and finds differences in retrieval time and mechanical effects.

Contribution

Presents a controlled in vitro comparison of three screw removal techniques for fractured dental implant abutment screws.

Findings

Fracture torque was higher when abutments were present during screw fracture.

Screws fractured without abutments engaged more internal threads and extended deeper into the screw channel.

The screw removal kit and fissure bur showed shorter retrieval times compared to the ultrasonic scaler.

Abstract

Introduction: The fracturing of abutment screws is a recurrent technical complication in implant-supported prostheses that may compromise prosthetic maintenance. Although multiple retrieval approaches have been described, comparative data under controlled experimental conditions remain limited. Materials and Methods: This in vitro pilot study evaluated the retrievability of fractured abutment screws when using three commonly applied instruments: an ultrasonic scaler, a fissure bur, and a screw removal kit. Eighteen implants from a single implant system were embedded in epoxy resin, and abutment screws were fractured under clockwise monotonic torque either with (w/A) or without (w/oA) abutments (n= 3 per retrieval method). Retrieval success and procedure time were recorded. Scanning electron microscopy (SEM) was performed to qualitatively assess deformation of the implant internal hex and screw thread morphology. Results: Fracture torque values were higher in specimens fractured with abutments compared with those without abutments. Fractures induced without abutments appeared to extend deeper within the screw channel, engaging a greater number of internal threads. In this pilot study, a shorter retrieval time was observed with the screw removal kit and fissure bur compared with the ultrasonic scaler, although retrieval outcomes varied between specimens. SEM observations suggested differing patterns of internal hex deformation between the retrieval techniques. Conclusions: Within the limitations of this in vitro pilot study, different retrieval approaches demonstrated characteristic mechanical behaviors and deformation patterns in the implant internal connection. These preliminary findings provide descriptive insight into the retrievability of fractured screws and may serve as a basis for future studies with larger sample sizes and clinically relevant fracture models.

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