Statement Of Problem: Flaws developed during polymerization of restorative materials cause a decrease in mechanical properties.
Purpose: The aim of this study was to determine the effect of polymerization under pressure on the indirect tensile mechanical properties (stiffness and diametral tensile strength) of several light-polymerized composites.
Material And Methods: Five light-polymerized composites were tested: Brilliant, Z100, TPH Spectrum, Prodigy, and Pertac Hybrid. A total of 80 cylindrical disk specimens (6 mm x 2 mm) were prepared for each material in a special mold that enabled polymerization under pressure (PUP). An equal number of specimens were polymerized under surface pressures of 0,.35,.71 and 1.06 MPa (n = 20). Stiffness (N/mm) and diametral tensile strength (DTS) (MPa) were analyzed while loading the specimen to failure with a loading machine. Two-way analysis of variance and Weibull analyses were applied (alpha=5%).
Results: Material type had a statistically significant influence on both DTS and stiffness (P<.0001). Differences up to 33% in DTS and up to 70% in stiffness values were found among the tested materials. Loading (PUP) had a significant influence on stiffness (P<.03) and DTS (P<.0001). PUP caused an increase in DTS values for Brilliant, Z100, and Prodigy of about 20% (P<.001) and increased stiffness only for Brilliant (15%). However, the amount of pressure needed for the improvement was different between materials (interaction between materials and loadings) (P<.0005). Weibull statistics showed that PUP improved the chances for reducing flaws in a material.
Conclusion: Polymerizing material under pressure can improve its DTS and stiffness. However, the pressure needed for the procedure is material dependent.
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| http://dx.doi.org/10.1067/mpr.2002.128100 | DOI Listing |
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