PURPOSE: The aim of this study was to evaluate the effect of repeated firings on the color of zirconia restoration with different shading method. MATERIALS AND METHODS: Three different types of zirconia frameworks (adding metallic pigments to the initial zirconia powder before sintering (Group NM), dipping the milled frameworks in dissolved coloring agents (Group KI), or application of liner material to the sintered white frameworks (Group KW) were used to support A3 shade dentin porcelain. Repeated firings (3, 5, or 7) were performed, color differences among ceramic specimens were measured using a colorimeter. Repeated measurements analysis of variance (ANOVA) was used to analyze the data for significant difference. The Tukey Honestly Significant Different (HSD) test was used to perform multiple comparisons (alpha = .05). RESULTS: 1. L*a*b* values of the ceramic systems were affected by the number of firings (1, 3, 5 or 7 firings) (P < .001) and shading methods (P < .001). 2. As the number of firings increased, the L* (for all groups) and a* value (for KW and NM groups) decreased and the b* value(for all groups) increased. 3. The mean color differences caused by repeated firings were perceptible (DeltaE > 1) for group KW and KI fired after 3 times, except for group NM fired after 7 times. 4. In order of decreasing DeltaE value fired after 7 times, the values were group KI(DeltaE = 2.26) > group KW (DeltaE = 1.47) > group NM (DeltaE = 1.08) (P < .001). CONCLUSION: Repeated firings influenced the color of the zirconium-oxide all-ceramic specimens with different shading methods.
Ceramics ; Coloring Agents ; Dental Porcelain ; Dentin ; Fires ; Humans ; Zirconium

BACKGROUND: Osteogenesis imperfecta (OI) is a congenital disorder of type I collagen, with variable phenotypes, due to increased bone fragility and low bone mass. Previous pharmacological treatments for OI have been attempted with calcitonin and growth hormone but with little beneficial effects. Recently, Glorieux reported the beneficial effects of bisphosphonates in OI. METHODS: In this study, the effects of pamidronate treatment were evaluated in 9 patients with OI. All patients received intravenous pamidronate infusions, which was dose adjusted according to the patients' age. The outcome measures included the biochemical bone markers; serum alkaline phosphatase, urine deoxy-pyridinoline, urine Ca/Cr ratio, and bone mineral density (BMD). RESULTS: Serum alkaline phosphatase, urine deoxypyridinoline, and urine Ca/Cr ratio were slightly decreased after 1 year of therapy, although these changes were not statistically significant. The BMDs of the lumbar spine and proximal femur were significantly increased after 1-year of pamidronate treatment. No fractures were reported during the 1 year treatment periods. CONCLUSION: Pamidronate treatment had an effect on the BMD in osteogenesis imperfecta, probably due to decreasing bone resorption
Alkaline Phosphatase ; Bone Density ; Bone Resorption ; Calcitonin ; Collagen Type I ; Congenital, Hereditary, and Neonatal Diseases and Abnormalities ; Diphosphonates ; Femur ; Growth Hormone ; Humans ; Osteogenesis Imperfecta* ; Osteogenesis* ; Outcome Assessment (Health Care) ; Phenotype ; Spine