Degree of conversion of self-adhesive cements: effect of restorative material and polimerization time.

Abstract

The present in vitro study aims to evaluate the conversion degree (%) of self-adhesive resinous cement Rely X U100. Three factors will be study: 1- restoration type used above the cement: without restoration, all reinforced ceramic restoration (CR) or metal-ceramic (MC), 2 - Type of photoactivation unit (halogen Lamp or LED) and 3- Period of time after polymerization: after 10 minutes (T1), after 1 hour (T2) and after 24 hours (T3). The analysis method that will be used is the spectrometric of infrared rays transformed of Fourier-FTIR. The samples (10mm of diameter and 0.5 mm of thickness) will be made through a silicon mold previously built. The samples will be positioned on the crystal of the spectrometer, it will be obtained infrared spectra with the program Spectrum (PerkinElmer) connected in a microcomputer. The program will be used with a resolution of 4 cm-1 and the spectra being collected in the interval from 1665 to 1580 cm-1. 32 readings will be accomplished for each sample. For the calculation of the conversion degree, the baseline technique will be used (Rueegeberg et al., 1990), that it will be drawn by the own program Spectrum. The corrected intensity of the picks observed in the wavelengths 1638 and 1608 cm-1 it will be used in the following formule: R = intensity in 1638cm-1 / intensity in 1608cm-1, being the conversion degree (%) = 100-(R of the cured cement / R of the no cured cement)*100. The data will be tabulated and submitted to the factorial statistical analysis (3X2X3) and test of multiple comparison of averages.