# Torsional resistance of additively, subtractively, and conventionally manufactured occlusal devices

## TL;DR

This study compares the torsional strength of different manufacturing methods for dental devices before and after aging.

## Contribution

It evaluates how aging affects the torsional resistance of additively, subtractively, and conventionally manufactured occlusal devices.

## Key findings

- Additively manufactured materials showed lower torsional resistance compared to subtractively and conventionally manufactured ones.
- Thermal cycling reduced torsional resistance in all materials, with additively manufactured ones showing the most significant decline.
- Material choice should consider clinical requirements due to varying torsional behavior after aging.

## Abstract

To investigate the torque load (TL) and angular rotation (AR) of additively, subtractively and conventionally manufactured occlusal devices.

Specimens (N = 120) were fabricated from four additive manufacturing resins (GR-10 guide, ProArt Print Splint clear, V-Print Splint, V-Print Splint comfort), five subtractively (BioniCut, EldyPlus, ProArt CAD Splint clear, Temp Premium Flexible, Thermeo) and one conventionally manufactured (Pro Base Cold) materials. The TL and AR were tested initially (24 h, 37 °C, H2O) as well as after thermal cycling (5,000 thermal cycles, 5/55°C). Data were analyzed using Kolmogorov–Smirnov, one-way ANOVA, Scheffé post-hoc, t-test, chi-square and Ciba-Geigy table (p < 0.05).

Initially, the mean TL values ranged from 63.7 to 104 Ncm for additively, 39.2 to 265 Ncm for subtractively, and 204 Ncm for conventionally manufactured materials. The initial mean AR values were 41.7 to 143 deg for additively, 38.4 to 138 deg for subtractively, and 29.3 deg for conventionally manufactured materials. After thermal cycling, the mean TL values ranged from 45.7 to 88.1 Ncm for additively, 31.2 to 246 Ncm for subtractively, and 138 Ncm for conventionally manufactured materials. The mean AR values after aging ranged from 19.9 to 124 deg for additively, 48.1 to 131 deg for subtractively, and 19.5 deg for conventionally manufactured materials.

The torsional resistance of additively, subtractively, and conventionally manufactured materials for occlusal devices varies and is affected by aging processes.

Material selection for occlusal devices should be guided by the clinical needs of the patients.