This study evaluated and compared the sealer thickness and interfacial adaptation of bioceramic sealers (Sankin Apatite III, MTA Fillapex^®, EndoSequence^® BC) to root dentin against AH Plus^® sealer. Sixty extracted single-root premolars were prepared and equally divided into four groups. Sealers were labeled with 0.1% Rhodamine B fluorescent dye. Roots were dissected along the transverse plane at 1 mm (apical), 3 mm (middle), and 6 mm (coronal) levels. Sealer-to-whole canal area ratio was evaluated. Percentage of gap-containing region to canal circumference was calculated using a confocal laser microscope. Sealer thickness was significantly higher at apical and middle levels than at coronal level. EndoSequence BC had the significantly highest thickness compared with MTA Fillapex and AH Plus. The coronal level had significantly less interfacial gaps compared with apical and middle levels. Bioceramic sealers showed more gaps compared with AH Plus, with no significant differences among them.