A comparative study of lateral condensation, heat-softened gutta-percha, and a modified master cone heat-softened backfilling technique

Aim The aim of the study was to compare the quality of root fillings completed by lateral condensation (LC), Thermafil (TF), and a new technique using Thermafil for backfilling (BF), with special emphasis on control of overfilling. Methodology Sixty curved canals in plastic blocks were prepared with the ProFile system to size 40/04 taper in the apical half and to 06 taper in the coronal half. The canals were divided into three groups of 20. Apical patency was verified with a size 15 K-file. The canals were then filled using three different techniques: LC ( 20 canals), TF ( 20 canals), and BF, where a size 40 master point with sealer was seated prior to the introduction of a size 30 Thermafil point (20 canals). The same resin-based sealer was used on each occasion. The root fillings were assessed using stereomicroscopy for material extrusion, digital radiography for occurrence of voids, and microscopy of sections for voids and thickness of sealer layer. Results Extrusion of both gutta-percha and sealer occurred in all 20 canals filled with the TF technique, but only three and five cases of sealer extrusion were detected with LC and BF techniques, respectively. No voids were detected in the TF group, whereas small voids were present in most fillings in the LC and BF groups. The average total length of the voids was less than 1 mm per canal. The thickness of the sealer layer in the middle and apical parts was greater in the LC and BF groups than in the TF group. Conclusions LC and BF techniques resulted in fewer overfills than TF. Voids were absent in TF fillings, whilst small voids were found in the LC and BF groups.