The Retrievability of Calcium Silicate-Based Sealer during Retreatment and the Effectiveness of Additional Passive Ultrasonic Irrigation: A Microcomputed Tomographic Study

Abstract

This study investigated the retreatability of EndoSeal MTA (Maruch, Wonju, Korea) according to the presence or absence of a canal isthmus and the additional use of passive ultrasonic irrigation (PUI) through microcomputed tomography (micro-CT) imaging. An epoxy resin sealer (AH Plus (Dentsply DeTrey, Konstanz, Germany)) was used as a reference for comparison. Forty-five artificial mandibular molars (TRUETOOTH #19, DELABS, Santa Barbara, CA) with a mesial canal with an isthmus and a distal canal without an isthmus were obturated using gutta-percha and one of the following sealers (n = 15 each): AH Plus, EndoSeal MTA, and EndoSeal MTA + PUI. Micro-CT scanning was performed to assess the void volume (as a percentage) at three root levels. After the root fillings were removed, second micro-CT scanning was conducted to evaluate the amount of remaining root filling material. The Kruskal-Wallis H test and post hoc analysis were used for between-group comparisons. The Mann-Whitney U test was used for comparisons between canals with and without an isthmus (p < 0.05). In the EndoSeal MTA group, the void volume and remaining filling materials were higher irrespective of the presence or absence of an isthmus. In apical lesions in the EndoSeal MTA group, the void ratio was significantly lower, and there was a significantly higher amount of remaining filling material. Regardless of the presence of an isthmus, the amount of remaining filling material of the EndoSeal + PUI group was reduced to a similar degree as the AH plus group. When performing retreatment for root canals filled with EndoSeal MTA, removal of the filling material can be more difficult in the apical region. The additional use of PUI can improve the efficacy of removal.

Figure 1

An artificial mandibular molar with an isthmus in the mesial canal.

Figure 2

Micro-CT reconstructed images of the remaining filling materials. Blue color indicates the remaining filling materials in the canal without isthmus, and orange indicates the remaining filling materials in the canal with isthmus: (a) AH Plus group; (b) EndoSeal MTA group; (c) EndoSeal MTA + PUI group.

Figure 3

Distribution of the percentage of voids in the filling material in canals with an isthmus between the AH Plus group and the EndoSeal MTA group. Data are presented as median (interquartile range). p values were computed using the Mann–Whitney U test. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.

Figure 4

Distribution of percentage of voids in the filling material in canals without an isthmus between the AH Plus group and the EndoSeal MTA group. Data are presented as median (interquartile range). p values were computed using the Mann–Whitney U test. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.

Figure 5

Distribution of the remaining ratio in canals with an isthmus among the AH Plus, EndoSeal MTA, and EndoSeal MTA + PUI groups. Data are presented as median (interquartile range). p values were adjusted using the Bonferroni post hoc method. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.

Figure 6

Distribution of the remaining ratio in canals without an isthmus among the AH Plus, EndoSeal MTA, and EndoSeal MTA + PUI groups. Data are presented as median (interquartile range). p values were adjusted using the Bonferroni post hoc method. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001.