Fig. 1

Experimental procedures. (a) Root canal after instrumentation. The outer root surface was covered with aluminum foil. (b) Matched gutta-percha cones were coated with BCS iRoot SP in CC, AC, and NC groups, respectively. (c) A matched gutta-percha cone was inserted into the root canal under an operating microscope. (d) A heat carrier was inserted into the canal to 4 mm from the working length using the continuous wave of condensation technique. (e) Gutta-percha was condensed with a BL-S Kondenser. The root canal was cleaned with paper points until BCS was not visible under an operating microscope. (f) A DT Light-Post Illusion X-RO finishing drill size 1 and a DT Light-Post Illusion X-RO size 1. (g) A fibre post was tried-in. (h) The post was fixed with Bond 1 as a primer and adhesive and Blue Build-it F.R. dual cure core material following the manufacturer’s recommendations. (i) Root canal after post fixation and removal of excess material. (j) Sample preparation: The red solid line and red cross indicate the apical 4 mm of the root was removed. The blue solid line indicates the dividing line between each third of the root. ‘C’ indicates the cervical third, ‘M’ indicates the middle third, and ‘A’ indicates the apical third of the root. The blue dashed line indicates the dividing line between specimen preparation for SEM study and PBS test. (k) PBS test: A pin was set at the center of the post and loaded in the apico-coronal direction at the rate of 1 mm/min until post dislodgement. Images a-j were captured by the same operating microscope with controlled magnification and settings set at 1.6 magnification (13.6-fold magnification)