Mechanical reliability of dental grade zirconia after laser patterning

Abstract

The aim of this work is to test the mechanical properties of dental zirconia surfaces patterned with Nd:YAG laser interference (λ = 532 nm and 10 ns pulse). The laser treatment produces an alteration of the topography, engraving a periodic striped pattern. Laser-material interaction results mainly in thermal effects producing microcracking, phase transformation and texturization. The role of such microstructural modifications and collateral damage on the integrity and mechanical performances has been assessed. Laser patterned discs of zirconia doped with 3% mol yttria (3Y-TZP) have been tested before and after a thermal treatment to anneal residual stresses and revert phase transformation. Both groups of samples behave in a similar manner, excluding residual stresses and phase transformation from the origin of properties modification. Result show that laser patterning induces a minor decrease in mechanical properties and surface integrity of 3Y-TZP surfaces. The biaxial strength decreases as a consequence of the damage induced by laser patterning. Fractographic observations identify preexisting defects enlarged by local laser interaction as the fracture origins. The Hardness and Young modulus of treated surfaces tested with nanoindentation also decrease slightly after laser treatment and this may be attributed to laser-induced microcracking.

Effects of Finish Line Design and Fatigue Cyclic Loading on Phase Transformation of Zirconia Dental Ceramics: A Qualitative Micro-Raman Spectroscopic Analysis

“…Zirconia is a restorative material widely used in dentistry and extensively tested for mechanical properties [46], fracture load [47], bond strength [48], cell proliferation [49], and translucency [10,50]. To date, in the authors’ knowledge, in the literature there are no reports that studied the top and the finish lines of zirconia copings with Raman spectroscopy, evaluating crystallographic changes soon after manufacturing milling and after chewing simulation.…”

Surface Modifications for Zirconia Dental Implants: A Review

“…Laser treatment is a fast, clean, contact-less, and easy-operating technique with high accuracy on material surfaces (32). The application of laser in dentistry began from the end of the 1990s on endodontic, periodontal, and oral surgery (33).…”

Microstructure and hydrothermal ageing of alumina-zirconia composites modified by laser engraving

“…The surface and subsurface modifications also affect the mechanical properties. This was studied in particular by Roitero et al [17] who observed a decrease in strength (but an increase of Weibull modulus) after lasing zirconia samples with a nanosecond Nd:YAG laser.…”