IADR Abstract Archives
Ageing Assessment of Zirconia Abutments by Different Quantitative Assessment Techniques
Objectives: Major drawback of yttrium stabilized tetragonal zirconia polycrystals (Y-TZP) is phase transformation related low temperature degradation (ageing). For the better understanding of ageing behavior in dental zirconia, clinical resemblance of artificial ageing conditions and effectiveness of ageing assessment techniques are important. Objectives: to evaluate the influence of cyclic loading on phase transformation of zirconia abutments and to compare the effectiveness of three different quantitative ageing assessment techniques.
Methods: Thirty two Y-TZP abutments fabricated from two brands: Incoris Zi and Ceramill Zi, were cemented to titanium base and equally divided into two groups for each brand (n=8): control groups without any treatment and aged groups with cyclic loading between 20N and 98N for100,000 cycles at 4Hz frequency in distilled water at 37degree Celsius. Tetragonal-monoclinic phase transformation was assessed and quantified by (i) conventional X-ray diffraction (XRD), (ii) micro X-ray diffraction ( µXRD2 ) and (iii) micro-Raman spectroscopy. Monoclinic-phase fractions (M%) were compared by three-way ANOVA and Tukey tests.
Results: Incoris Zi presented significantly higher M% (~3%) than Ceramill Zi in both control and aged groups (P<0.001). Both materials exhibited significant phase transformation at all three techniques with monoclinic-phase of 1 to 2% more in aged groups than controls (P=0.008). Slightly higher M% (<1%) was quantified by µXRD2 than XRD (P=0.73). Lowest M% was assessed with micro-Raman spectroscopy (P≤0.001).
Conclusions: Cyclic loading induced significant phase transformation in Y-TZP abutments. Different values of M% extracted by each technique may be due to differences in sample volume assessed by respective technique.
Methods: Thirty two Y-TZP abutments fabricated from two brands: Incoris Zi and Ceramill Zi, were cemented to titanium base and equally divided into two groups for each brand (n=8): control groups without any treatment and aged groups with cyclic loading between 20N and 98N for100,000 cycles at 4Hz frequency in distilled water at 37degree Celsius. Tetragonal-monoclinic phase transformation was assessed and quantified by (i) conventional X-ray diffraction (XRD), (ii) micro X-ray diffraction ( µXRD2 ) and (iii) micro-Raman spectroscopy. Monoclinic-phase fractions (M%) were compared by three-way ANOVA and Tukey tests.
Results: Incoris Zi presented significantly higher M% (~3%) than Ceramill Zi in both control and aged groups (P<0.001). Both materials exhibited significant phase transformation at all three techniques with monoclinic-phase of 1 to 2% more in aged groups than controls (P=0.008). Slightly higher M% (<1%) was quantified by µXRD2 than XRD (P=0.73). Lowest M% was assessed with micro-Raman spectroscopy (P≤0.001).
Conclusions: Cyclic loading induced significant phase transformation in Y-TZP abutments. Different values of M% extracted by each technique may be due to differences in sample volume assessed by respective technique.