LIGHT-CURED GLASS-IONOMER CEMENT AS A RETROGRADE ROOT SEAL

A light-cured glass ionomer cement was investigated as a retrograde root seal, without a retrograde cavity. This was compared with the material used in a retrograde cavity, and with a conventional glass ionomer cement, as a seal. The adaptation and sealing ability of the test materials were assessed using a confocal optical microscope with a fluorescent dye. The root canals of 40 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were subsequently apicected, then divided into four equal groups. In one group, a retrograde cavity was prepared, and the light-cured glass ionomer cement was placed as a retrograde root filling. No retrograde cavities were prepared in the three remaining groups. The light-cured glass ionomer cement was applied directly onto the apicected root face. Two different thicknesses of light-cured glass ionomer cement were tested, a thin layer (almost-equal-to 1 mm) in one group, and a thicker layer (> 1 mm) in another group. A conventional glass ionomer cement was used in the last group, and applied directly onto the root face in a single thickness (almost-equal-to 1 mm). In the group where the light-cured glass ionomer cement was used in a retrograde cavity, the material was often well adapted to one cavity wall, but gaps were found on the opposite wall. The light-cured and conventional glass ionomer cement retrograde root seals were well adapted to the root face, regardless of the thickness of material used. The thinly applied (almost-equal-to 1 mm) light-cured glass ionomer cement retrograde root seals permitted the least leakage. This was significantly less than the light-cured glass ionomer cement used with a retrograde cavity (P < 0.001). The greatest extent of dye penetration was found with the thick (> 1 mm) light-cured and conventional glass ionomer cement (almost-equal-to 1 mm) root seals; the differences between these were not significant. The light-cured glass ionomer cement was only suitable as a retrograde root seal when a thin layer (almost-equal-to 1 mm) was used.