Marginal leakage of Gallium Alloy root-end fillings: an in-vitro assessment

The sealing ability of amalgam and Gallium Alloy Gallium Filling (GF) root-end fillings was evaluated in vitro using a highly uniform collection of sheep incisor roots. Following ultrasonic canal debridement and orthograde obturation with gutta-percha and sealer, root-end cavities were prepared in 100 roots and filled with amalgam (50 teeth) or Gallium Alloy GF (50 teeth), Twenty-five teeth from each group were subjected to immediate dye leakage assessment under vacuum conditions with methylene blue dye (2%), pH 7. Linear dye penetration was measured following longitudinal splitting. The other 25 teeth from each group were incubated in Ringer's solution for 12 weeks before leakage assessment by the same method. Control teeth were included in each component of the study. Mean linear dye penetration was: amalgam--5.17 mm at baseline, 2.33 mm after 12 week's incubation; Gallium Alloy GF--2.21 mm at baseline, 1.41 mm after 12 week's incubation. The apical marginal seal of both materials improved significantly following storage in Ringer's solution (P<0.001). Gallium Alloy GF provided a better apical seal than amalgam, both at baseline and following storage (P<0.001). Subjective evaluation of the general handling characteristics of Gallium Alloy GF revealed that it was a more difficult material to manipulate than amalgam, largely because of its wetting ability and consequent adhesion to dental instruments.