Influence of an iodonium salt on the properties of dual-polymerizing self-adhesive resin cements.
BACKGROUND
Dual-polymerizing self-adhesive resin cements present mechanical properties that may adversely affect the clinical performance of luted fiber-reinforced posts.


OBJECTIVE
The purpose of this in vitro study was to evaluate the properties of dual-polymerizing self-adhesive resin cements after the addition of an onium salt.


METHODS
The experimental groups were set according to the molar concentration of diphenyliodonium hexafluorphosphate (DPIHFP) (0.5, 1, and 2 mol%). The resin cements were submitted to a push-out bond strength test and assessed for flexural strength (ISO 4049/2009), degree of conversion (Fourier-transformed infrared spectroscopy), depth of polymerization, swelling coefficient, and degradation in solvent. The data were statistically analyzed by ANOVA, Tukey test, Kruskal-Wallis test, Dunn multiple comparison, and paired Student t test (α=.05).


RESULTS
All the RelyX U100 groups with onium salt showed the highest degree of conversion after 24 hours and 7 days (P<.001). However, no statistical difference was found among the BisCem groups (P=.054). The addition of 0.5 mol% DPIHFP increased the push-out bond strength and microhardness of RelyX U100 and promoted less degradation after immersion in solvent. The BisCem control group did not present a statistical difference from the experimental groups in terms of bond strength; the control group and the 0.5 mol% group showed no degradation in solvent. For swelling coefficient and flexural strength, no difference was found between the BisCem groups (P=.067 and P=.173), and the RelyX U100 2 mol% group presented the lower value (P<.001 and P=.048). Depth of polymerization was not statistically different in the experimental groups for either resin cement (P=.999).


CONCLUSIONS
The addition of 0.5 mol% DPIHFP improved the physical properties of dual-polymerizing self-adhesive resin cements.
Graduate student, Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Carolina Rocha
CR
Augusto
Professor, Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
Vicente Castelo Branco
VCB
Leitune
Professor, Materials Engineering School, Federal University of Pelotas, Pelotas, Brazil.
Fabrício Aulo
FA
Ogliari
Professor, Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. Electronic address: fabricio.collares@ufrgs.br.
Fabrício Mezzomo
FM
Collares
D001713:Biphenyl Compounds; D003764:Dental Materials; D008422:Materials Testing; D009861:Onium Compounds; D058105:Polymerization; D019279:Resin Cements; D012492:Salts
D001713:Biphenyl Compounds; D003764:Dental Materials; D009861:Onium Compounds; D019279:Resin Cements; D012492:Salts; C031291:diphenyliodonium