Preventing Porcelain Fractures During Endodontic Treatment.

Attempting endodontic access through ceramic or veneering porcelain can be wrought with challenges. Clinicians must take every precaution to assist patients who are in pain without causing harm through chipping or fracturing the restoration. This article discusses strategies clinicians can consider when facing the task of achieving endodontic access through an all-ceramic crown.

Effect of grain size on the monoclinic transformation, hardness, roughness, and modulus of aged partially stabilized zirconia.

Objective: Low-temperature-degradation (LTD) has been reported to cause property changes in yttria-tetragonal zirconia polycrystals (Y-TZP). The current study measured monoclinic phase transformation of Y-TZP with different grain sizes and corresponding property changes due to artificial aging.

Null Hypothesis: the grain size of aged Y-TZP will not influence its transformation, roughness, hardness or modulus of elasticity.

Phase transformation of dental zirconia following artificial aging.

Aims: Low-temperature degradation (LTD) of yttria-stabilized zirconia can produce increased surface roughness with a concomitant decrease in strength. This study determined the effectiveness of artificial aging (prolonged boiling/autoclaving) to induce LTD of Y-TZP (yttria-tetragonal zirconia-polycrystals) and used artificial aging for transformation depth progression analyses. The null hypothesis is aging techniques tested produce the same amount of transformation, transformation is not time/temperature dependent and LTD causes a constant transformation throughout the Y-TZP samples.