Microbial status of apical root canal system of human mandibular first molars with primary apical periodontitis after ‘‘one-visit’’ endodontic treatment

By Nair PN, Henry S, Cano V, Vera J

Date: 04/2006
Journal: OOO Endo


Purpose:  To assess the in vivo intracanal microbial status of the apical root canal system of mesial roots of human #36 or 46 with primary apical periodontitis using transmission electron microscopy

N= 16 apical mesial roots of mandibular first molars


  • LA, RD isolation, disinfected by NaOCl, access, WL. All MB canals were instrumented using K hand files #25. All ML canals were instrumented using Lightspeed NiTi until a #40 apical size.
  • Irrigation with 5.25% NaOCl, 17% EDTA, obturated by lateral condensation of GP & ZOE cement.
  • The apical third of mesial roots was carefully removed by surgery after completing the  RCT.
  • Control: +ve , extracted teeth with  PA;  -ve, extracted healthy premolars

Most highlighted Results: 

1.Microorganisms were found in the apical root canal system in 14/16 (88%)

2.11\16 root tips revealed an isthmus between canals, 10/11 showed presence of microorganisms.

3.Accessory root canals were present in 8 \16, of which 5 contained a mixed microbial flora.

4.The microbes were located in inaccessible intercanal isthmus, and accessory canals, mostly as biofilms.

Clinical significance:

Findings highlight the importance of chemomechanical measures in order to disrupt the biofilms to ensure the most favorable long-term prognosis for treatment of infected root canals.