Filling Quality of MTA Canal Obturation in Type Ⅲ Root Canal with Isthmus

Abstract

Objectives The objective of this study was to compare the filling quality of mineral trioxide aggregate (MTA) canal obturation with lateral compaction (LC) and continuous wave of condensation (CW) in type III mesial root canals with isthmuses of the mandibular first molars using micro-computed tomography (micro-CT). The null hypothesis was that there is no significant difference in filling quality among the three obturation techniques in the main root canals and the isthmus.

Materials and Methods The mesial roots of 60 extracted human mandibular first molars with type Ⅲ canal configuration by Weine that had an interconnecting isthmus were prepared to an apical size of #40. The specimens were allocated into three groups of 20 roots for obturation by either LC or CW using a gutta-percha and AH Plus sealer, or by MTA canal obturation with OrthoMTA (MTA). The obturated roots were scanned by micro-CT (Skyscan 1172). The filled volume ratio (%) in the main canal or in the isthmus at the apical third was calculated using CTAn software. The filled volume ratio was defined as the ratio of the sum of the obturated gutta-percha and sealer volume or MTA to the main canal or isthmus volume. Data were statistically analyzed using the Kruskal-Wallis test or Mann-Whitney U test applying a significance level of 0.05.

Results Reconstructive micro-CT images demonstrated that the LC group had lower filling densities in the isthmus than either CW or MTA. Unfilled radiolucent voids were shown in two samples in the MTA group. The filled volume ratio was not significantly different among the three groups for the main canals (p > 0.05). In the isthmus, the filled volume ratio for LC was lower than in CW and MTA (p < 0.05). The volume ratio of the gutta-percha for LC was significantly lower in the isthmus than that of CW, whereas the volume ratio of the sealer was significantly greater (p < 0.05).

Conclusions MTA canal obturation showed comparable filling quality to LC or CW techniques in the main canal or isthmus.