The effect of photoactivation time and light tip distance on the degree of conversion of light and dual-cured dentin adhesives.

BACKGROUND

The degree of conversion of dental adhesive is an important parameter since poor mechanical properties are related to low percentage of monomer-to-polymer conversion within resin-based materials.

OBJECTIVES

To evaluate the influence of polymerization time and light guide distance on the degree of conversion (DC) of three contemporary dental adhesives.

MATERIALS AND METHODS

The spectral data of ExciTE DSC, Single Bond ® , and Adper ® Prompt L-Pop were analyzed using FTIR spectroscopy after 20 s, 40 s, and 60 s of photoactivation times. Light tip distances were kept at 1, 3, and 6 mm during the exposures.

STATISTICS

Data were analyzed using ANOVA and Tukey's test (α = 0.05).

RESULTS

Within groups, greater DC values were found using a tip distance of 1 mm or a 60-s curing time for Single Bond ® (59%) and Adper ® Prompt L-Pop (65%). No statistically significant difference (P > 0.05) was found using either 1 mm or 3 mm tip distances after 20 s, 40 s, and 60 s of light curing time for Single Bond ® . ExciTE ® DSC showed the greatest DC values with light tip distances of 1 mm (90%) and 3 mm (89%), using 60 s of light curing.

CONCLUSION

The self-etch adhesive Adper ® Prompt L-Pop could be applied in shallow cavity preparations and must be light cured for at least 40 s. The light-cured total-etch adhesive ExciTE ® DSC could be applied in every restorative scenario if the curing time is extended up to 60 s or if the tip distance is extended up to 3 mm.