The effect of Alumina, Silica and Zirconia infiltration on the flexural strength and fracture toughness of glass ceramic blocks

Abstract

Introduction: Ceramics are inherently fragile and prone to defeat under bending forces. In the intraoral condition, the restoration must have sufficient strength to withstand repeated masticatory forces. The aim of this study was to compare the flexural strength and fracture toughness of two types of glass ceramics IPS e-max CAD and Suprinity after infiltration with the silica, alumina and zirconia sols. Materials and Methods: 160 specimens of both glass ceramics were divided into four groups (10 samples) based on the type of infiltration sols (zirconia, silica and alumina) and tested for flexural strength (80 samples) and fracture toughness (80 samples). Flexural strength and fracture toughness were measured using a three-point bending test according to ISO 6872:2015. X-ray diffraction (XRD) of the samples was performed with the aid of Cu kα radiation (MIRA 3 XMU, TESCAN) and the surface analysis of the samples was carried out by FE-SEM (FEI Helios Nanolab 650). Results: The highest flexural strength and fracture toughness were observed in IPS e-max CAD glass ceramics. IPS e-max CAD glass ceramics infiltrated with Zirconia sol and Suprinity glass ceramics infiltrated with Silica sol had the highest fracture strength(343/68±65/80 and 312/05±59/15 respectively). Also, the highest fracture toughness in IPS e-max CAD ceramics and Suprinity ceramic were observed after infiltration with Zirconia. (170/22±22/08 and 105/39±15/74) Conclusion: IPS e-max CAD glass ceramics are the best high strength materials for dental restorations. Also, their strength is further improved by the zirconia nanoparticles addition. Zirconia infiltrated IPS e-max CAD and silica infiltrated Suprinity glass ceramics had the highest flexural strength compared to their control groups(P=0.008 , P=0.001). Also the highest fracture toughness was seen in zirconia infiltrated glass ceramics(IPS e-max CAD and Suprinity) compared to control groups.