# In vitro assessment of internal implant-abutment connections with different cone angles under static loading using synchrotron-based radiation

## TL;DR

This study examines how different implant-abutment connection designs behave under static loading using high-precision imaging techniques.

## Contribution

The study introduces a high-accuracy method using synchrotron-based radiation to assess microgap behavior and abutment displacement in implant systems.

## Key findings

- Microgaps increased with loading force and angle, reaching up to 40.5 μm under 100 N at 90°.
- Friction-fit connections with small cone angles caused outer implant wall deformation.
- Implant-abutment design significantly affects force distribution and potential bone stability.

## Abstract

The stability of implant-abutment connection is crucial to minimize mechanical and biological complications. Therefore, an assessment of the microgap behavior and abutment displacement in different implant-abutment designs was performed.

Four implant systems were tested, three with a conical implant-abutment connection based on friction fit and a cone angle < 12 ° (Medentika, Medentis, NobelActive) and a system with an angulated connection (< 40°) (Semados). In different static loading conditions (30 N − 90º, 100 N − 90º, 200 N − 30º) the microgap and abutment displacement was evaluated using synchrotron-based microtomography and phase-contrast radioscopy with numerical forward simulation of the optical Fresnel propagation yielding an accuracy down to 0.1 μm.

Microgaps were present in all implant systems prior to loading (0.15–9 μm). Values increased with mounting force and angle up to 40.5 μm at an off axis loading of 100 N in a 90° angle.

In contrast to the implant-abutment connection with a large cone angle (45°), the conical connections based on a friction fit (small cone angles with < 12°) demonstrated an abutment displacement which resulted in a deformation of the outer implant wall. The design of the implant-abutment connection seems to be crucial for the force distribution on the implant wall which might influence peri-implant bone stability.