Effect of translucent zirconia at different colours and thicknesses on resin cement polymerization

Patient expectations were arised with in the development of full ceramic restorations. Monolithic zirconia (Translucent Zirconia, TZI) is a zirconia material that's developed for this purpose. The purpose of this study was to evaluate the degree of conversion of two resin cements which polymerized beneath different thickness and colour of TZI specimens. TZI specimens were prepared as three different thicknesses (0.5, 1, 2 mm) and four different colours (A1, A2, A3, A4) from partially sinterized TZI blocks (n=5). Dual cure and light cure resin cements used for this study. Resin cements were applied into teflon molds and irradiated with LED curing unit with 20s beneath TZI specimens (n=10). Resin specimens were stored at room temperature with dry conditions. Each sample's monomeric metacrylate (aliphatic) and polymeric metacrylate degree measured by fourier transform infrared spectoscopy (FT-IR) after 1th and 10th days. Degree of conversions were calculated. Data were analysed with two-way repeated-measured analyses of variance, three-way repeated-measured analyse of variance and Tukey LSD tests (p<0.05). Light cured resin groups showed higher degree of conversion than dual cure groups. Degree of conversion of both resin cements reduced by increased TZI thickness. Degree of conversion reduced when TZI specimens coloured with dark colours. Although there was not statitstically meaning difference on light cure resin groups between 1th day and 10th day values, there was a statistically meaning increase on 10th day values of dual cure resin groups. Within the limitations of this study light cure resin cements could be offered for luting TZI restorations.