FLUID TRANSPORT AND DYE PENETRATION ALONG ROOT-CANAL FILLINGS

Dye penetration along root canal fillings may be hindered by the prese nce of entrapped air. In this study, the sensitivity of a dye penetrat ion method was compared with that of a fluid transport model. Sixty ro ot sections from human maxillary central incisors were prepared and ob turated by a modified technique to ensure a slight amount of leakage, and divided into three equal groups. Twenty root sections were first m ounted in a fluid transport device and assessed for fluid transport un der 10 kPa (0.1 atm.) pressure. Another 20 root sections were mounted in the same device before being subjected to air transport under the s ame pressure. The remaining 20 root sections were not exposed to fluid or air transport. Then, all the 60 root sections were assessed for pe netration of a 2% methylene blue solution. The results showed that flu id transport was a much more sensitive method of detecting voids along root canal fillings than dye penetration. After fluid transport for 3 h under low pressure, to eliminate entrapped air, dye penetrated sign ificantly deeper than without previous fluid transport, which suggeste d that entrapped air in voids along the root canal filling prevented d ye penetration.