Summary:
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
Materials/Methods:
- 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.


