# Effect of Post-Processing Heat Treatment on Micro-Contact Damage of Zirconia-Reinforced Lithium Silicate Dental Materials

## TL;DR

This paper studies how heat treatment affects the durability of a dental material used for crowns, finding it improves resistance to damage without changing basic strength properties.

## Contribution

The novel contribution is demonstrating that heat treatment improves contact damage resistance in ZLS dental material through flaw refinement.

## Key findings

- Heat treatment does not alter elastic modulus, hardness, or indentation fracture toughness of ZLS.
- Heat treatment increases resistance to fracture and chipping in axial and sliding contact modes.
- Refined flaw population from heat treatment enhances crack initiation resistance in sliding tests.

## Abstract

Zirconia-reinforced lithium silicate (ZLS) is utilized as a material for prosthetic tooth crowns, offering enhanced strength compared to other dental glass-ceramics. In this study, we investigate a commercial ZLS material, provided in a fully crystallized form. We examine the effects of an optional post-processing heat treatment on micro-contact damage using controlled indentation tests simulating the primary modes of contact during chewing: axial and sliding. Our findings indicate that the heat treatment does not affect mechanical properties such as the elastic modulus, hardness and indentation fracture toughness. However, it does enhance the resistance to contact damage by fracture and chipping in both axial and sliding modes, as well as the resistance to crack initiation measured from sliding tests. This improvement is attributed to the refinement of the flaw population achieved through the heat treatment. The results are analysed using principles of contact and fracture mechanics theory, discussing their significance in prosthetic dentistry.