Abstract
BackgroundAim of the study was to verify the efficiency of Martens hardness measurements in detecting the degradation of composite resin cements during artificial aging.MethodsFour cements were used: Variolink II (VL2), RelyX Unicem 2 Automix (RUN), PermaFlo DC (PDC), and DuoCem (DCM). Specimens for Martens hardness measurements were light-cured and stored in water at 37 °C for 1 day to allow complete polymerization (baseline). Subsequently the specimens were artificially aged by water storage at 37 °C or thermal cycling (n = 6). Hardness was measured at baseline as well as after 1, 4, 9 and 16 days of aging. Specimens for indirect tensile strength measurements were produced in a similar manner. Indirect tensile strength was measured at baseline and after 16 days of aging (n = 10). The results were statistically analyzed using one-way ANOVA (α = 0.05).ResultsAfter water storage for 16 days hardness was significantly reduced for VL2, RUN and DCM while hardness of PDC as well as indirect tensile strength of all cements were not significantly affected. Thermal cycling significantly reduced both, hardness and indirect tensile strength for all cements. No general correlation was found between Martens hardness and indirect tensile strength. However, when each material was analyzed separately, relative change of hardness and of indirect tensile strength revealed a strong linear correlation.ConclusionsMartens hardness is a sensible test method to assess aging of resin composite cements during thermal cycling that is easy to perform.
Highlights
Aim of the study was to verify the efficiency of Martens hardness measurements in detecting the degradation of composite resin cements during artificial aging
Priming is accomplished by bifunctional monomers in the primer such as HEMA, which are applied at first and bind to the tooth substance with a hydrophilic end while the hydrophobic end contains a polymerizable group that can bind to the resin composite cement [15]
After water storage for 16 days hardness was significantly reduced for Variolink II (VL2) (p = 0.008), RelyX Unicem Automix (RUN) (p = 0.006), DCM (p = 0.022) and PermaFlo DC (PDC) (p < 0.001) while indirect tensile strength of all cements were not significantly affected (p > 0.05)
Summary
Aim of the study was to verify the efficiency of Martens hardness measurements in detecting the degradation of composite resin cements during artificial aging. Ceramic materials provide high aesthetic options but they are susceptible to tensile stress, which implies a higher risk of failures during functional loading, such as veneer chipping or fractures [9,10,11]. To prevent any tensile stress in the ceramic, the restoration should not exhibit mechanical retention on the prepared tooth [12]. In a second step the tooth surface must be primed in order to make it wettable to a hydrophobic resin composite cement. Priming is accomplished by bifunctional monomers in the primer such as HEMA, which are applied at first and bind to the tooth substance with a hydrophilic end while the hydrophobic end contains a polymerizable group that can bind to the resin composite cement [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
