Reduction of intracanal bacteria using GT rotary instrumentation, 5.25% NaOCl, EDTA, and Ca(OH)₂

This study was conducted to determine the bacterial reduction using Profile GT® files and a strict irrigation protocol utilizing 5.25% NaOCl and EDTA. The additive antibacterial effect of Ca(OH)₂ was also evaluated. In addition, the study compared the bacterial reduction with the GT protocol versus larger instrumentation. Thirty-one subjects with apical periodontitis were recruited. Bacterial samples were taken upon access (S1), after instrumentation and a strict irrigation protocol (S2), and following >1 wk of Ca(OH) ₂ (SC). A log₁₀ transformation of colony forming units was done since sample bacterial counts are not normally distributed. At S1, 93.55% of canals sampled bacteria. At S2, 52.72% of the cases sampled bacteria. At SC, 14% of the cases cultured bacteria. The McNemar test showed a significant reduction (p < 0.0009) in bacteria between S1 and S2. This was also true between S2 and SC (p < 0.0019). It was concluded the GT protocol significantly reduced the number of bacteria in the canal but failed to render the canal bacteria free in more than half of the cases Ca(OH)₂ application significantly further reduced bacteria. Lastly, large apical instrumentation removed more bacteria than small apical instrumentation.