RESUMEN
The purpose of this study was to evaluate the effect of gravity and capillarity on penetration of human salivary bacteria into the entire length of obturated root canals, and to demonstrate the dye penetration configuration. Fifty single-rooted premolars were decoronated, prepared to a standardized length of 15 mm, instrumented, and randomly divided into two groups [A and B] of 25 teeth each. Each group consisted of experimental [15 samples] and negative and positive controls [five samples each]. The experimental groups were obturated with gutta-percha and root canal sealer. The positive control groups were obturated with a single cone of gutta-percha and root canal sealer. The outer surfaces [except for the apical 2 mm] were covered with two layers of nail varnish. An apparatus containing Brain Heart Infusion broth was designed, in which the teeth were placed. The samples in Group A were placed upside down, while Group B was placed normally. The coronal portions of the samples were placed in contact with fresh saliva. The number of days required for bacteria to penetrate the entire length of canals was determined. The samples were then immersed in India ink to determine the dye penetration configuration. Data were analyzed using Student's Mest. The extent of dye penetration was significantly greater in Group B compared to Group A, and they were in a pattern rather than linear form. Gravity and capillarity insignificantly affected bacterial leakage. Although gravity and capillarity did not affect bacterial penetration when applied to the coronal access of endodon-tically treated teeth, it seems that they can promote penetration of India ink into the canal after the bacterial test on the same tooth