Filling Quality Assessment of Four Obturation Techniques in Mandibular First Molar Mesial Root Canals Using Micro-CT

Objectives: This study assessed the filling quality of four canal obturation techniques in mandibular first molar mesial root canals using micro-computed tomography (MCT).
Methods: Forty extracted human mandibular first molar mesial roots with two separate canals were prepared to an apical size 30/.06. They were randomly allocated to four groups for obturation by either lateral compaction (LC), continuous wave of condensation (CW), or a hybrid (HY) technique, which all used gutta-percha and AH Plus sealer; or by an orthograde MTA obturation using OrthoMTA (BioMTA, Seoul, Republic of Korea). The obturated roots were scanned by MCT and assessed for the volumetric ratio (%) of gutta-percha, sealer, OrthoMTA, and void within the main canals or isthmuses in the apical 5 mm area. Additionally, the obturated roots were cross-sectioned and examined by stereomicroscopy. Measurements were analyzed statistically for differences among the obturation techniques, and between the main canals and isthmuses.
Results: The filled volume ratio in the main canal was higher than that in the isthmus (p < 0.001). The filled volumes within isthmus were not significantly different among groups (p > 0.05). The gutta-percha volume within isthmus in CW was significantly higher than that in the LC (p = 0.021). HY showed significantly lower filled volume ratio in the main canals than LC, CW, or MTA (p < 0.05). Abundant smear layer was identified within unfilled isthmus space by stereomicroscopy.
Conclusions: HY demonstrated lower filling density than LC, CW and MTA. OrthoMTA showed comparable filling quality to gutta-percha with sealer.