Quantitative and qualitative analyses of ceramic chipping

Objective To evaluate edge chip resistance (ReA) and fractographic features of ceramic systems submitted to edge chipping. Methods Samples were fabricated using the following materials: YZ-yttria-stabilized tetragonal zirconia ceramic (IPS e.max® Zir-CAD); LG-leucite-reinforced glass-ceramic (IPS Empress® CAD); LD-lithium-disilicate glass-ceramic (IPS e.max® CAD); ZF- YZ veneered by a pressable fluorapatite glass-ceramic (IPS e.max® Zir-CAD + IPS e.max® Zir-Press); ZD- YZ-LD fused together by a glass-ceramic (IPS e.max® Zir-CAD + IPS e.max® crystall./connect + IPS e.max® CAD). Half of the sample size was bonded (B) to a dentine analogue substrate (NEMA G10) and the remaining samples were kept non-bonded (NB). Structures were indented (n = 25) at different edge distances (d = 0.3, 0.4, 0.5, 0.6, 0.7 mm) using a universal testing machine to produce chips. Force (F) and d values were recorded and ReA was calculated. Data were statistically analyzed using ANOVA, Student t and Tukey tests (α = 0.05). Chipping was evaluated visually and under optical and scanning electron microscopy based on fractography principles. Results Data (F vs d) showed a positive linear trend for all groups. There was no significant difference in ReA values at d = 0.5 mm (SE0.5) between NB and B for same ceramic system. Fracture pattern was similar between NB and B for same ceramic system at d = 0.5 mm. Conclusions Bonding neither influenced ReA values nor the fracture pattern that were similar between NB and B structures from same ceramic system. The greater the distance from structure edge, the lesser the chance of chipping occurred.