Influence of thermo-mechanical cycling on porcelain bonding to cobalt-chromium and titanium dental alloys fabricated by casting, milling, and selective laser melting

Maja Antanasova; Andraž Kocjan; Janez Kovač; Borut Žužek; Peter Jevnikar

doi:10.1016/j.jpor.2017.08.007

Influence of thermo-mechanical cycling on porcelain bonding to cobalt-chromium and titanium dental alloys fabricated by casting, milling, and selective laser melting

J Prosthodont Res. 2018 Apr;62(2):184-194. doi: 10.1016/j.jpor.2017.08.007. Epub 2017 Sep 6.

Authors

Maja Antanasova¹, Andraž Kocjan², Janez Kovač³, Borut Žužek⁴, Peter Jevnikar⁵

Affiliations

¹ University of Ljubljana, Faculty of Medicine, Department of Prosthodontics, Ljubljana, Slovenia.
² Jožef Stefan Institute, Department for Nanostructured Materials, Ljubljana, Slovenia.
³ Jožef Stefan Institute, Department of Surface Engineering and Optoelectronics, Ljubljana, Slovenia.
⁴ Institute of Metals and Technology, Ljubljana, Slovenia.
⁵ University of Ljubljana, Faculty of Medicine, Department of Prosthodontics, Ljubljana, Slovenia. Electronic address: peter.jevnikar@mf.uni-lj.si.

PMID: 28886950
DOI: 10.1016/j.jpor.2017.08.007

Abstract

Purpose: The aim has been to determine the effect of thermo-mechanical cycling on shear-bond-strength (SBS) of dental porcelain to Co-Cr and Ti-based alloys fabricated by casting, computer-numerical-controlled milling, and selective-laser-melting (SLM).

Methods: Seven groups (n=22/group) of metal cylinders were fabricated by casting (Co-Cr and commercially pure-cpTi), milling (Co-Cr, cpTi, Ti-6Al-4V) or by SLM (Co-Cr and Ti-6Al-4V) and abraded with airborne-particles. The average surface roughness (R_a) was determined for each group. Dental porcelain was applied and each metal-ceramic combination was divided into two subgroups - stored in deionized water (24-h, 37°C), or subjected to both thermal (6000-cycles, between 5 and 60°C) and mechanical cycling (10⁵-cycles, 60N-load). SBS test-values and failure modes were recorded. Metal-ceramic interfaces were analyzed with a focused-ion-beam/scanning-electron-microscope (FIB/SEM) and energy-dispersive-spectroscopy (EDS). The elastic properties of the respective metal and ceramic materials were evaluated by instrumented-indentation-testing. The oxide thickness on intact Ti-based substrates was measured with Auger-electron-spectroscopy (AES). Data were analyzed using ANOVA, Tukey's HSD and t-tests (α=0.05).

Results: The SBS-means differed according to the metal-ceramic combination (p<0.0005) and to the fatigue conditions (p<0.0005). The failure modes and interface analyses suggest better porcelain adherence to Co-Cr than to Ti-based alloys. Values of R_a were dependent on the metal substrate (p<0.0005). Ti-based substrates were not covered with thick oxide layers following digital fabrication.

Conclusions: Ti-based alloys are more susceptible than Co-Cr to reduction of porcelain bond strength following thermo-mechanical cycling. The porcelain bond strength to Ti-based alloys is affected by the applied metal processing technology.

Keywords: Bond strength; CAD/CAM; Metal–ceramic; Selective laser melting; Titanium.

MeSH terms

Alloys
Chromium Alloys*
Cobalt*
Dental Alloys*
Dental Bonding*
Dental Porcelain*
Dental Stress Analysis
Freezing
Lasers
Shear Strength*
Stress, Mechanical
Titanium*

Substances

Alloys
Chromium Alloys
Dental Alloys
Dental Porcelain
titanium alloy (TiAl6V4)
Cobalt
Titanium