Antimicrobial effect of root canal débridement in teeth with immature root. A clinical and microbiologic study

The aim of present investigation was to compare the antibacterial effect of biochemical root canal cleansing in permanent non-vital upper incisors with immature with those with mature root. The material comprised three groups made up of 34, 46 and 28 teeth in which the mechanical cleansing was accompanied by flushing with sterile saline and sodium hypochlorite solutions giving 0.5 or 5.0% active chloride, respectively. Samples were taken in root canals initially after removal of necrotic tissue and after completed cleansing, transferred to solid and liquid media for aerobically and anaerobically and incubated until growth appeared or up to 10 days. The microorganisms were identified by biochemical tests and gas-chromatographic analysis. The antibacterial effect of mechanical cleansing with sterile saline was very low (9%) and limited to the teeth with mature root. The flushing with sodium hypochlorite increased the antibacterial effect to about 25%. No statistical difference was found in the antibacterial effect between flushing with 0.5 % or 5.0% sodium hypochlorite solutions. The antibacterial effect was, however, irrespective of the sodium hypochlorite concentrations, less good in teeth with immature root at the statistically significant 5% level. It was concluded that mechanical cleansing of root canals in teeth with immature root with the instruments now available is inadequate. This inadequacy cannot be compensated for by use of highly concentrated solution, with dissolving effect on necrotic tissue, for flushing. The use of such substances which also have toxic effect on the tissue should be avoided.