Micro-Raman Assessment of the Ratio of Carbon-Carbon Double Bonds of Two Adhesive Systems Cured with LED or Halogen Light-curing Units

Purpose The purpose of the study was to compare the ratio of carbon carbon double bonds (RDB) of two adhesive systems cured by five different light curing units (LCUs) using micro Raman spectroscopy

Materials and Methods Ten samples of an etch and rinse (Excite) a two-step self etching adhesive system (AdheSE) - ie primer and bond mixed - and AdheSE Bond only were prepared and cured with one of the following LEDs Elipar Freelight2 Bluephase Smart Lite, Coltolux, each for 10 s, or a conventional halogen Prismetics Lite for 10 s or 20 s Micro-Raman spectra were obtained from uncured and cured samples of all three groups to calculate the RDB Data were statistically analyzed using ANOVA

Results The mean RDB values were 62% to 76% (Excite), 36% to 50% (AdheSE Primer+Bond) and 58% to 63% (Ad heSE Bond) At 20 s, Prismetics Lite produced significantly higher RDB in Excite than the other LCUs and Prismetics Lite at 10 s (p < 0 05) Prismetics Lite at 20 s and Elipar produced comparable RDB values of AdheSE Bond and Ad heSE Primer+Bond (p > 0 05) Excite showed significantly higher RDB values than AdheSE (p < 0 05) whilst AdheSE Bond showed significantly higher RDB than AdheSE Primer+Bond (p < 0 05)

Conclusion The etch and rinse adhesive cured with the halogen LCU for 20 s gave higher conversion than LED LCUs or halogen for 10 s curing time The highest intensity LED [Elipar] produced higher or comparable conversion compared to the lower intensity LED LCUs for the same curing time The etch and rinse adhesive showed higher RDB than the self etching adhesive system The presence of the primer in the self etching adhesive compromised polymerisaton