Setting Reaction of Polyacid Modified Composite Resins or Compomers

“Objectives:” In the present work, we have studied the compomer hardening reaction using FTIR looking at the changes in the bands attributed to the methacrylate double bonds and a conventional ionomer to evaluate a possible acid-base reaction.“Methods:” Three commercial materials were  used in the present  study. The Ketac-fil (KF. 3M, Espe) a conventional ionomer;  Hytac (HY. 3M, Espe) and Compoglass (CP. Ivoclar, Vivadent), both compomers. The spectra were obtained following the KBr method. IR spectra were obtained using a Nicolet Magna II spectrometer (Madison, Wisconsin), at a nominal resolution of 2 cm^-1, averaging 1000 scans. “Results:” KF glass ionomer: the decrease in polycarboxylic acid is very rapid and in 10 minutes arrives at around 35% of the percentage in equilibrium. However, in the bands corresponding to the COO^- components, it is also the maximum for the 1630 cm^-1 band at 10 min, where there is a 1590 cm^-1 band increase at the expense of the other component. Regarding the HY and CP compomers, we found a patent decrease in the C=C band at 1638 cm^-1 from the methacrylate that can be clearly seen together with the disappearance of other methacrylate  bands around 1300 and 1150 cm. This change in the spectrum does not indicate involvement of an acid-base process in the hardening reaction, but rather a polymerization of methacrylate present in the cement. The change in shape and position observed in the band at 1720 cm^-1 would imply involvement of the carboxylic acid in the cross-linked organization obtained after the polymerization reaction. “Conclusion:”In  view of the results, we can conclude that no acid-base reaction was observed as a hardening mechanism in the Polyacid -modified composite restorative resins or compomers Hytac and Compoglass. Furthermore, both compomers may be lacking the fluoride release inherent in such a reaction system.