Comparison of warm vertical compaction protocols to obturate artificially created defects in the apical one-third

The purpose of this study was to evaluate the ability of 4 different warm vertical compaction protocols to obturate artificially created defects in the apical one-third of a root canal system by using a split-tooth model.

Four warm vertical protocols used (A) continuous down-pack and continuous backfill, (B) continuous down-pack and incremental backfill, (C) incremental down-pack and continuous backfill, and (D) incremental down-pack and incremental backfill. Three artificially created defects were placed 2, 3, and 4 mm from the apex of the split-tooth model. Before obturations, a fine-medium System B plugger was prefitted 4 mm from the working length. The root canal system was obturated according to each of the experimental protocols. Resultant obturations (N = 10/protocol) were separated from the model, and replicated defects were assessed by a blinded evaluator who used an ordinal scale (0-4) that was based on how much each defect was replicated by GP.

By using nonparametric analyses with Bonferroni adjustment (α = 0.01), with the apical 2-mm defect, protocol D demonstrated significantly (P ≤ .01) better defect replication as compared with protocols A, B, and C. For the apical 3-mm defect, protocols B and D were significantly better (P ≤ .01) than protocols A and C. However, there was no difference (P > .01) between protocols with apical 4-mm defect (100% replication).

The incremental down-pack with incremental backfill appears better able to replicate the most apical defect, which suggests benefits of repeated heat application and packing force to manipulate the GP in the apical plug area.