RESUMO
Objectives@#This study aimed to evaluate the ability of lithium disilicate ceramics to reproduce the A2 shade and to mask A4 substrates. @*Materials and Methods@#Twenty-four discs (8 mm in diameter, shade A2) of high translucency (groups 1–3) and low translucency (groups 4–6) of IPS e.max ceramic with different thicknesses (0.5, 0.75, and 1 mm) were fabricated as monolithic structures. In addition, discs of medium opacity (group 7–8) with different core/veneer combinations (0.3 mm/0.7 mm and 0.5 mm/0.5 mm) were fabricated as bilayer structures. Specimens were superimposed on an A4 substrate (complex). The color changes of the complex were measured using a spectrophotometer on a black background, and the ΔE values of the complex were compared with either the A4 substrate or the A2 shade tab. One-way analysis of variance, the Tukey honest significant difference test, and the Fisher test were used to analyze the data (p < 0.05). @*Results@#Significant between-group differences were found for comparisons to both the A4 substrate and the A2 shade (p < 0.05). When compared with the A4 substrate, the ΔE values in all groups were in the non-acceptable range. When compared with the A2 shade, the ΔE values in all groups, except groups 2 and 3, were in the clinically acceptable range. @*Conclusions@#All translucencies and thicknesses masked the underlying dark substrate.However, the low-translucency IPS e.max Press better reproduced the A2 shade.
RESUMO
Objectives@#This study aimed to evaluate the ability of lithium disilicate ceramics to reproduce the A2 shade and to mask A4 substrates. @*Materials and Methods@#Twenty-four discs (8 mm in diameter, shade A2) of high translucency (groups 1–3) and low translucency (groups 4–6) of IPS e.max ceramic with different thicknesses (0.5, 0.75, and 1 mm) were fabricated as monolithic structures. In addition, discs of medium opacity (group 7–8) with different core/veneer combinations (0.3 mm/0.7 mm and 0.5 mm/0.5 mm) were fabricated as bilayer structures. Specimens were superimposed on an A4 substrate (complex). The color changes of the complex were measured using a spectrophotometer on a black background, and the ΔE values of the complex were compared with either the A4 substrate or the A2 shade tab. One-way analysis of variance, the Tukey honest significant difference test, and the Fisher test were used to analyze the data (p < 0.05). @*Results@#Significant between-group differences were found for comparisons to both the A4 substrate and the A2 shade (p < 0.05). When compared with the A4 substrate, the ΔE values in all groups were in the non-acceptable range. When compared with the A2 shade, the ΔE values in all groups, except groups 2 and 3, were in the clinically acceptable range. @*Conclusions@#All translucencies and thicknesses masked the underlying dark substrate.However, the low-translucency IPS e.max Press better reproduced the A2 shade.
RESUMO
Objectives: periapical Granulomas [PGs] and Radicular Cysts [RCs], as the most common odontogenic lesions have yet unclear pathogenesis. This study was aimed to compare PCNA and Ki-67 expression in PGs and RCs and evaluate their possible relationship with two lesions
Methods: in this cross-sectional descriptive study, twenty PGs and twenty RCs were evaluated immunohistochemically using an anti-PCNA and anti-Ki-67 polyclonal antibodies. PCNA[+] and Ki-67[+]cells were counted in connective tissue wall and epithelial lining [in RCs]. Statistical analysis was performed by using Mann-Whitney U test and Spearman's rank correlation coefficient
Results: in PGs, percentage of PCNA and Ki-67 expression were found 70% and 30%, respectively; In RCs, PCNA and Ki-67 expression were observed 90% and 55%, respectively. Additionally, in RCS, Immunoexpression of PCNA [85%] and Ki-67 [60%] were detected at epithelial lining area. The positive immunoexpression of PCNA in RCs was greater than PGs [p<0.05]
Conclusion: immunoexpression of PCNA and Ki-67 were detected in both lesions which may be mentioned as valuable markers for the prediction of biologic behavior of PGs and RCs