Technique for Darkening of Extracted Teeth Simulating Pulpal Necrosis Staining

Objectives: The aim of this study was to present a technique for darkening extracted teeth simulating pulpal necrosis staining, for in vitro models.
Methods: Samples of human blood were processed to obtain solutions of hemolysates I and II and aliquots of them were submitted to laser (442nm) for 1h, with homogenizations every 15min. Samples were analyzed immediately after collection and after 3 and 40 days. The concentration of oxyhemoglobin (oxyHb) was analyzed by transmittance spectroscopy (ST) and oxyhemoglobin concentration (oxyHb) by ultraviolet / visible (UV / VIS) spectroscopy in triplicate. For the evaluation of the darkening, bovine incisors (n=6) had the cervical third of the root sectioned, and hemolysate solution II and hemolysate II solution + laser were inserted inside the pulp chamber. After sealing it with glass-ionomer cement the tooth was immersed in artificial saliva for 40 days at 37°C, with changes every 24h. The color changes obtained on the extracted teeth were measured with the calorimeter and from the parameters of the CIELab system the ΔE was calculated.
Results: The hemolysate II solution submitted to laser action for one hour was the one with the lowest concentration of oxyHb and higher concentration of metaHb. The conversion of oxyHb to metaHb in the laser irradiated sample was 42% higher than the non-irradiated sample.
Conclusions: According to the parameters of the NBS, the analysis of the results proved the effectiveness of the proposal technique for darkening extracted teeth simulating pulpal necrosis staining. The use of hemolysate II solution promoted an intense color difference in relation to the natural color of the darkened teeth in vitro, however, with the application of laser in this solution, most of the teeth changed color according to the NBS parameters.