Bonding surface pretreatment of zirconia ceramic dental restorations with a nanostructured alumina coating (NAC) provides a substantially stronger and durable bond than clinically established air-particle abrasion. However, the synthesis of NAC should completely comply with everyday dental laboratory practices. In the present study, the effect of various dental laboratory firing procedures, such as glaze, veneer and regeneration firings of zirconia, on the temperature-dependent phase evolution of NAC was studied (XRD) and related to the resin-cement shear-bond strength of as-sintered, high-pressure (4 bar) and low-pressure (1 bar) air-particle-abraded zirconia surfaces with or without a combination of MDP primer. Half of each sample groups (n = 20) were subjected to 12000% thermocycles in water. The results were statistically analysed using t-test and one-way ANOVA. When fired at 900 and 1050°C and topotactically transformed to gamma- or a mixture of delta- and theta-aluminas, NAC provided highest and clinically acceptable bond-strengths ()20Mpa) not affected by thermocycling.
COBISS.SI-ID: 34446553
We report on a new approach to increase the fracture resistance of endodontically treated teeth. We propose a preparation of horizontal internal plateau (IP) in dentine and the use of retentive zirconia posts to achieve a more favourable load transmission. The aim of our work was to investigate the effect of the IP depth and the post diameter on the fracture resistance and the failure mode of maxillary central incisors. Seventy-two teeth were, divided into six groups of 12. IP 4 mm in diameter and 0, 1 or 2 mm in depth was prepared and zirconia posts of two diameters luted. Specimens were loaded until failure and fractures were classified as reparable or not. Two-way ANOVA, Tukey%s HSD test and Poisson regression were used for statistical analysis (% = 0.05). Significantly improved fracture resistance and predominantly favourable failure modes were found when 2-mm deep IP is prepared.
COBISS.SI-ID: 31645735