DECOLORATION OF 1-PERCENT METHYLENE-BLUE SOLUTION IN CONTACT WITH DENTAL FILLING MATERIALS

Objectives: Leakage studies have been performed frequently, since a ti ght seal provided by various dental fillings has been considered clini cally important. The dye penetration experiment using a methylene blue solution as a tracer is one of the most common methods applied in the se types of studies. The stability of the colour of methylene blue in contact with six dental filling materials was observed. Methods: Silic on rubber tubes and human tooth roots of 10 mm in length and 1.5 mm in ner diameter were filled with amalgam, calcium hydroxide, Cavit, Fuji II, mineral trioxide aggregate, or zinc oxide eugenol, 10 tubes or roo ts for each material. Groups of five tubes or roots filled with the sa me material were immersed in 0.8 ml 1% methylene blue dye solution. Th e optical density of the methylene blue solution before immersion and after 24, 48 and 72 h of immersion was measured in a spectrophotometer at 596 nm. Results: The methylene blue solution was found to be decol oured over time by all the test materials (P < 0.01) except for Fuji I I, in both silicone tubes and roots. At 24 h, the optical density valu e of methylene blue decreased by 73% for the Ca(OH)(2)/silicone group and 84% for the mineral trioxide aggregate/silicone group. Conclusion: Methylene blue is decoloured by some dental filling materials, which may result in unreliable results for these materials in dye leakage st udies. (C) 1998 Elsevier Science Ltd. All rights reserved.