Curing potential of dual-polymerizable resin cements in simulated clinicalsituations

Statement of problem. Little is known about the ability of dual-polymerizab le resin cements to polymerize when they are used in various clinical scena rios. Purpose. This study was conducted to determine whether any of 6 commerciall y available dual-polymerizable resin cements should be classified as an "al l-purpose" resin cement. Material and methods. Chemical conversion values (C=C converted to C-C, or the extent of the curing reaction) of 6 commercially available dual-polymer izable resin cements were determined with infrared spectroscopy in 5 clinic ally relevant scenarios. Scenarios included: using each cement in a dual-po lymerizable mode (mixing of 2 pastes); light polymerizing curing through My lar sheets (dual-Mylar), which served as the control; light polymerizing th rough 3-mm porcelain (dual-3 mm); and no exposure to light (dual-no light). The single-component light-polymerizable product was also tested as follow s: exposed directly through Mylar (light-Mylar) or exposed through 3 mm of porcelain (light-3 mm). Results. For each product, dual-Mylar treatment yielded the highest convers ion value of all treatments (control for each product). For all products, d ual-3 mm conversion was at least 97% of control and equivalent to control, with the exception of Lute-It!. Dual-no light conversion was less than cont rol treatment but at least 86% of control for all products except for Vario link II (62% of control). For all products in dual-no light mode, except Ch oice and Variolink II, conversion was at least equal to the light-Mylar val ues. Only 1 product (Variolink II) did not demonstrate increased conversion values for dual-Mylar compared with light-Mylar treatments. For most other products (Calibra, Insure, and Lute-It!), conversion values for light-3 mm were significantly less than for light-Mylar. Conversion values for Nexus, Choice, and Variolink II were equivalent between light-Mylar and light-3 m m treatments. Conclusion. The choice of a dual-polymerizable cement should be based on it s intended use because not all products polymerize adequately in every clin ical situation. Although no cement met the stated criteria for an "all-purp ose" cement, those tested did produce a range of product-specific results.