Periapical Inflammation after Coronal Microbial Inoculation of Dog Roots Filled with Gutta-Percha or Resilon

A dog model was used to assess and compare in vivo the efficacy of gutta-percha and AH26 sealer versus Resilon with Epiphany primer and sealer [Resilon “Monoblock” System (RMS)] filled roots in preventing apical periodontitis subsequent to coronal inoculation with oral microorganisms. There were 56 vital roots in the premolars of seven adult beagle dogs aseptically instrumented, filled, and temporized. The roots were randomly divided into four experimental groups (Coronal Leakage Model) and one negative control group and filled as follows: group 1-lateral condensation of gutta-percha and AH26 sealer (n=12); group 2-vertical condensation of gutta-percha and AH26 sealer (n=12); group 3-lateral condensation of RMS (n=12); group 4-vertical condensation of RMS (n=10); negative control (n=10)-gutta-percha and AH26 sealer or RMS root fillings using lateral or vertical condensation techniques as in groups 1 to 4. Positive control-57 additional premolar roots were instrumented, infected and not filled (beginning of the Entombment Model experiment). The premolars in groups 1 to 4 were accessed again, inoculated with dental plaque scaled from the dog's teeth, and temporized. This fresh innoculum of microorganisms was repeated on two more occasions at monthly intervals. The teeth in the negative control group were not accessed again and remained undisturbed. On the 14-wk postcoronal inoculation, dogs were euthanized, and jaw blocks prepared for histologic evaluation under a light microcope. Mild inflammation was observed in 82% (18 of 22) of roots filled with gutta-percha and AH26 sealer that was stastistically more than roots filled with RMS (19% or 4 of 21) and roots in the negative control (22% or 2 of 9) (McNemar paired analysis, p < 0.05). The Resilon “Monoblock” System was associated with less apical periodontitis, which may be because of its superior resistance to coronal microleakage.