Quantitative and qualitative analyses of ceramic chipping.

Objective: To evaluate edge chip resistance (R) 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 R 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 R values at d = 0.5 mm (S0.5) 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 R 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.