Homogeneity of root canal fillings performed by undergraduate students with warm vertical and cold lateral techniques

The aim of this study was to determine radiographic and microscopic appearances of root canal fillings performed by undergraduate students using vertical and lateral compaction techniques.

Thirty dental students were instructed how to fill curved simulated canals with gutta-percha and sealer using lateral and vertical compaction. Digital radiographs were taken in buccolingual and mesio-distal projections; radiographs were evaluated for homogeneity and root canal wall contact. Plastic blocks with simulated canals were sectioned and cross sections were assessed under a light microscope for voids. Probabilities were expressed as odds ratios (OR) with 95% confidence intervals (CI).

Radiographs showed that the chances of obtaining a homogeneous root canal filling by using a vertical compaction technique were 3 times higher in the coronal canal third (OR 3.2; CI: 1.9, 5.3), the same in the middle third, and 2 times higher in the apical third (CI: 1.1, 2.4) than when using lateral compaction. Microscopic evaluation of the same canals revealed that the chances of obtaining a homogeneous root canal filling by vertical compaction were 3 times higher in the coronal canal third (CI: 1.6, 5.8), almost 3 times higher in the middle canal third (CI: 1.6, 4.7), and about 10 times higher in the apical canal third (OR 9.8; CI: 2.2, 43.4) than by lateral compaction. The chances of transporting filling material beyond the apex were almost 5 times higher (OR 4.6; CI: 2.8, 7.6) when using vertical rather than lateral compaction.

Inexperienced students obtained more homogeneous root canal fillings with the vertical compaction method; however, the probability of overextruding filling material with this method was high.