Evaluation of two instrumentation techniques and obturation methods in mandibular first premolar C- shaped canals by Micro-CT

Abstract Aim To investigate the effect of instrumentation using Protaper Next (PN, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) and Waveone Gold (WG, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) systems on the area of untouched surface (US), accumulated hard tissue debris (AHTD), and the filling ability of two obturation techniques on the percentage of void within C-shaped root canals of mandibular first premolars. Methodology: 64 mandibular first premolars with C-shaped canals were scanned, matched and assigned to 2 shaping groups (n = 32): PN and WG. Following instrumentation, specimens were randomly assigned into two obturation subgroups (n = 16): continuous wave compaction (CWC) and single-cone (SC) techniques. The US% and AHTD% after instrumentation and the vol% of void after obturation were calculated from micro-computed tomography. Data were analyzed using comparisons for two groups (PN vs WG) or two subgroups (CWC vs SC) at α = 0.05. Results For PN and WG, 18.75% and 22.69%, respectively, of the canal wall remained untouched (p > 0.05). For both groups, the apical third had higher US% than the coronal third (p < 0.05). Instrumentation with WG left more debris (26.48%) than PN (8.36%) in the apical 1-3mm (p < 0.05). In PN and WG group, the vol% of void had no significant difference between the CWC and SC subgroups(p > 0.05). The apical region had significantly more voids than the coronal region of the canal space in the two obturation subgroups regardless of which system was applied (p < 0.05). Conclusions Both PN and WG systems were associated with similar US after instrumenting C-shaped canals of the mandibular first premolar. WG left significantly more AHTD compared with PN in the apical region. In PN or WG group, SC yielded similar obturation quality when compared with CWC. Both CWC and SC obturation techniques provided poorer filling quality in the apical region than in the coronal region. Clinical Significance: Micro-CT evaluation of the PN and WG shaping C-shaped canals in mandibular first premolars showed similar effects on the percentages of untouched canal wall. The PN produced less hard tissue debris in the apical regions compared with the WG. The SC yielded similar obturation quality compared with the CWC.