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 vith 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.