RESUMO
Statement of Problem: Fracture of veneering porcelain has been described as the most frequent reason for the failure of zirconia-based fixed restorations
Objectives: The purpose of this study was to evaluate and compare the shear bond strength of a zirconium oxide core material to three commercial veneering ceramics
Materials and Methods: Three types of veneering ceramics were selected including IPS -emax Ceram, Vita VM9, and Cerabien. Thirty block specimens of zirconia core material were prepared in 4x4x9 mm dimensions. Three groups were created and the veneering ceramic was added to each of 10 blocks. Shear bond test was conducted with universal testing machine. Data were analyzed using one-way ANOVA [p = 0.05]
Results: Mean shear bond strength values and standard deviations were 26.03 MPa [6.32], 23.85 MPa [4.01], and 19.16 MPa [3.72] for Vita VM9, IPS emax Ceram, and Cerabien, respectively. Cerabien ceramic showed more failure as compared to the other ceramics. However, there was no significant difference among the three veneering groups
Conclusions: Within the limitation of this study, it can be concluded that shear bond strength between zirconia core and three veneering ceramics was not significantly different
Assuntos
Resistência ao Cisalhamento , Colagem Dentária , Cerâmica , ZircônioRESUMO
Statement of Problem: Dental prosthesis is usually made indirectly; therefore dimensional stability of the impression material is very important. Every few years, new impression materials with different manufacturers' claims regarding their better properties are introduced to the dental markets which require more research to evaluate their true dimensional changes
Objective: The aim of this study was to evaluate dimensional stability of additional silicone impressionmaterial [Panasil[R] and Affinis] in different time intervals
Materials and Methods: In this experimental study, using two additional silicones [Panasil[R] and Affinis[R]], we made sixty impressions of standard die in similar conditions of 23 °C and 59% relative humidity by a special tray. The die included three horizontal and two vertical lines that were parallel. The vertical line crossed the horizontal ones at a point that served as reference for measurement. All impressions were poured with high strength dental stone. The dimensions were measured by stereo-microscope by two examiners in three interval storage times [1, 24 and 168 hours].The data were statistically analyzed using t-test and ANOVA
Results: All of the stone casts were larger than the standard die. Dimensional changes of Panasil and Affinis were 0.07%, 0.24%, 0.27% and 0.02%, 0.07%, 0.16% after 1, 24 and 168 hours, respectively. Dimensional change for two impression materials wasn't significant in the interval time, expect for Panasilafter one week [p = 0.004]
Conclusion: According to the limitations of this study, Affinis impressions were dimensionally more stable than Panasil ones, but it was not significant. Dimensional change of Panasil impression showed a statistically significant difference after one week. Dimensional changes of both impression materials were based on ADA standard limitation in all time intervals [< 0.5%]; therefore, dimensional stability of this impression was accepted at least until one week