Evaluation of Different Techniques for Filling Simulated C-shaped Canals of 3-dimensional Printed Resin Teeth

The purpose of this study was to compare the ability of different root canal filling methods on the C1 root canal anatomy using 3-dimensional (3D) printer technology.

Mandibular molars were scanned with cone-beam computed tomographic (CBCT) imaging. A mandibular molar tooth with a C1 root canal configuration was selected according to images obtained from CBCT technology. The root canals were shaped with ProTaper Universal rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) and hand files. After the root canal shaping procedure, the tooth was scanned with micro-computed tomographic imaging, and 80 replicas of the tooth were produced with a 3D printer. Replicas were assigned into 4 groups (n = 20) and were filled using one of the following techniques: a core carrier system (GuttaCore [GC]; Dentsply Tulsa Dental Specialties, Tulsa, OK), a continuous wave obturation system (Elements Free [CW]; Kerr/SybronEndo, Orange, CA), a cold lateral compaction technique (CLC), or the injectable cold filling method (GuttaFlow Bioseal [GFB]; Coltène/Whaledent AG, Altstatten, Switzerland). All specimens were sectioned horizontally at 2, 4, 6, 8, and 10 mm from the apices of the specimens. The sections were examined at 32× magnification under a stereomicroscope, and the percentage areas of gutta-percha, sealer, and voids were measured. Statistical analysis of data was performed using multivariate analysis of variance and Tukey honestly significant difference tests (P < .05).

The CW group had the highest mean percentages for void and the least mean percentages for gutta-percha at 2-mm sections (P < .05). A pairwise comparison between the groups showed significantly less void in the CLC and GFB groups and more void in the CW and GC groups at 2 mm (P < .05). In the total area, the CLC and GFB groups showed a significantly lower percentage of gutta-percha and more sealer compared with the other groups (P < .05), and there was no significant difference between the CLC and GFB groups (P > .05).

At the apical part of the canal, the cold lateral compaction and cold injectable filling techniques were more successful compared with the warm gutta-percha filling techniques in C1 root canal configuration.