Fourier-transform (FT)-Raman and infrared (IR) spectroscopy were employed to investigate the function of the aqueous 2-hydroxyethylmethacrylate (HEMA)/glutaraldehyde (GA) solution (Gluma) as a desensitizer.Materials and Methods:
HEMA, GA, and the mixture of HEMA + GA were used to interact with dentin, collagen, hydroxyapatite (HAP), and bovine serum albumin (BSA) individually. To look at dentin, freshly extracted molars were sectioned into 1.5-mm thick dentin slices, pretreated with 37% phosphoric acid for 30 seconds, washed, and dried. The slices were cut into four blocks which were immersed in the solutions. Then collagen and HAP were immersed as well. BSA was diluted 1:3 to simulate dentinal fluid and the materials tested with it.Results:
The FT-Raman spectrum of dentin, the interaction of GA, HEMA, and Gluma with collagen and HAP, and the interaction of GA, HEMA, and Gluma with BSA were tabulated. HEMA was shown to be absorbed onto the dentin surface and because of the hydrogen bond between HEMA and dentinal collagen, it could not be removed by washing, indicating that HEMA acts as a preprimer attaching to collagen. Collagen was cross-linked by glutaraldehyde, which strengthens the collagen fibrils. There is a compound formed when BSA is cross-linked with GA. The cross-linking of BSA by Gluma results in precipitation that occludes the dentinal tubules.Conclusions:
When Gluma is applied in vivo, two reactions occur. First, GA reacts with part of the serum albumin in dentinal fluid, which induces a precipitation of serum albumin. Second, the reaction of GA with serum albumin induces the polymerization of HEMA. The function of Gluma as a desensitizer to block dentinal tubules is completed by these two reactions.