# Novel nonmagnetic abutment designs for facial prostheses: an experimental study

## TL;DR

This study tested new nonmagnetic abutments for facial prostheses and found they provided better retention than traditional magnetic systems.

## Contribution

The paper introduces and evaluates two novel nonmagnetic abutment designs as alternatives to magnetic systems for facial prostheses.

## Key findings

- Nonmagnetic abutments showed significantly higher retentive forces than magnetic systems at all dislodging cycles.
- Retention forces decreased over time in all groups, but the nonmagnetic systems retained more force than the magnetic system.
- The highest initial retentive force was observed in the nonmagnetic abutment type 1 system.

## Abstract

This in vitro study was undertaken with the aim of evaluating and comparing the retentive forces of novel nonmagnetic abutment designs developed as alternatives to conventional magnetic abutments for facial prostheses.

A plexiglass model was constructed and two extraoral implants were placed in these blocks in a parallel position. Nonmagnetic abutments made of titanium were fabricated and screwed onto the implants. The nonmagnetic systems represent a novel design and include two different abutment designs (type 1 and type 2) with silicone attachments. Retentive force values for the three abutment types of a conventional magnetic system (CMS), the nonmagnetic abutment type 1 system (NMS1), and the nonmagnetic abutment type 2 system (NMS2) were measured at the 0th, 120th, 360th, 720th, and 1440th dislodging cycles using a test machine. Given the data’s distribution characteristics, nonparametric tests were used for analysis. The Kruskal–Wallis test was used to evaluate significant differences among groups, followed by Dunn’s posthoc test for specific group comparisons. The Friedman test compared the number of dislodging cycles for each group, and the Benjamini–Hochberg adjusted Wilcoxon sign-rank test was used for pairwise comparisons.

Both NMS1 and NMS2 exhibited significantly higher retentive forces compared to CMS for the same dislodging cycles (p < 0.01). The NMS1 group showed the highest initial retentive force (9.98 ± 0.89 N), followed by the NMS2 group (9.65 ± 0.35 N), but this difference was not statistically significant. Significant differences in retention force values were observed among the three groups across the dislodging cycles (p < 0.001). The lowest retentive force in the last dislodging cycle was observed in the CMS group (3.39 ± 0.04 N). Additionally, the retention forces decreased in all groups with each increasing dislodging cycle.

The two newly developed nonmagnetic systems displayed higher retentive forces compared to the magnetic systems and can be considered viable alternative abutment options for facial prostheses.