A preliminary study of the percentage of gutta-percha-filled area in the apical canal filled with vertically compacted warm gutta-percha

Aim The aim of this study was to determine the influence of the width of apical root canals and the depth of heat application during warm vertical compaction on the percentage of gutta-percha-filled area (PGFA) in the apical root canal. Methodology Two groups of extracted human canines (total 60) were instrumented and filled with vertically compacted warm gutta-percha up to the apical foramen (AF). Using the Touch 'n Heat device heat was applied 4 mm from the AF in one group and 2 mm in the other. The number of teeth with gutta-percha extrusion was recorded. A horizontal section was cut 1.5 mm from the AF of each tooth. The cross-sectional area of the canal and the gutta-percha was measured using an image-analysis programme. The PGFA was then calculated. Multiple linear regression was performed to investigate the association between the experimental variables and the PGFA, and the occurrence of gutta-percha extrusion. Results A significant association was seen between the depth of heat application and the PGFA (P = 0.000), and between the canal area and the PGFA (P = 0.038). The average PGFA reached 96.1% when heated to 2 mm, as compared with 87.0% when heated to 4 mm. PGFAs were lower in wide apical canals than in small canals. Gutta-percha extruded in seven teeth (12%) and was independent of experimental variables. Conclusions After warm vertical compaction, the quality of adaptation of gutta-percha to the wall of the apical root canal varies; the influencing factors in this study were the depth of heat application and the width of the apical root canal.