Reduction in bacterial counts in infected root canals after rotary or hand nickel–titanium instrumentation – a clinical study


Correspondence: José F. Siqueira Jr, Faculty of Dentistry, Estácio de Sá University, Rua Alfredo Baltazar da Silveira, 580/cobertura, Recreio, Rio de Janeiro, RJ 22790-710, Brazil (e-mail:



To compare the antibacterial efficacy of two instrumentation techniques, one using hand nickel–titanium (NiTi) instruments and the other using rotary NiTi instruments, in root canals of teeth with apical periodontitis.


Root canals from single-rooted teeth were instrumented using either hand NiTi instruments in the alternated rotation motion technique or rotary BioRaCe instruments. The irrigant used in both groups was 2.5% NaOCl. DNA extracts from samples taken before and after instrumentation were subjected to quantitative analysis by real-time polymerase chain reaction (qPCR). Qualitative analysis was also performed using presence/absence data from culture and qPCR assays.


Bacteria were detected in all S1 samples by both methods. In culture analysis, 45% and 35% of the canals were still positive for bacterial presence after hand and rotary NiTi instrumentation, respectively (> 0.05). Rotary NiTi instrumentation resulted in significantly fewer qPCR-positive cases (60%) than hand NiTi instrumentation (95%) (= 0.01). Intergroup comparison of quantitative data showed no significant difference between the two techniques.


There was no significant difference in bacterial reduction in infected canals after instrumentation using hand or rotary NiTi instruments. In terms of incidence of positive results for bacteria, culture also showed no significant differences between the groups, but the rotary NiTi instrumentation resulted in more negative results in the more sensitive qPCR analysis.