FLUID TRANSPORT AND BACTERIAL PENETRATION ALONG ROOT-CANAL FILLINGS

Convective transport of water from the coronal to the apical end of ob turated root canals was determined by the movement of an air bubble in a capillary glass tube connected to the apex of the experimental root section using a headspace pressure of 120 kPa (1.2 atm). Water transp ort through existing voids in the obturated canals could be measured r eproducibly in this way. The root canals of 60 human maxillary canines were filled with gutta-percha and sealer by the cold lateral condensa tion technique. Thirty of these were first exposed to a small motile b acterium, Pseudomonas aeruginosa, growing in a reservoir at the corona l end of each root. After 50 days, two specimens allowed penetration o f bacteria to a reservoir at the apical end. All the roots were then a ssessed quantitatively for convective transport of water. The results were divided into three defined categories: 39 obturated canals were i n the 'bacteria tight' category, 14 canals in the 'slight leakage' and 7 canals in the gross leakage' category. The two specimens that showe d bacterial penetration fell into the slight and gross leakage categor ies. The previous test for bacterial passage did not statistically inf luence the fluid transport pattern of these roots which was measured s ubsequently. These findings indicate that fluids transport through obt urated root canals, most of which do not allow the passage of bacteria .