Temperature rise on the external root surface during removal of endodontic fractured instruments.

OBJECTIVES

To investigate the temperature rise (TR) on the external root surface while preparing a staging platform, for removing intra-canal fractured instruments, using Gates Glidden (GG) drills.

MATERIALS AND METHODS

Thirty extracted mandibular incisors were decoronated and 3-3.5 mm of F3 ProTaper files were fractured 3 mm from the most coronal end of the root. Roots were divided into three groups. GG drills were used in a size-2 to size-5 sequence to prepare the staging platform coronal to the fractured segment. They were rotated at three speeds according to the study groups: group A for 2,000 revolutions per minute (rpm); group B for 4,000 rpm; and group C for 8,000 rpm. Temperature changes were recorded at the proximal and buccal or lingual external root surfaces while preparing the staging platform. Data were analyzed using the paired sample T, one- and two-ways ANOVA tests at p ≤ 0.05.

RESULTS

Overall, TR at the proximal root surface (5.44 °C) was significantly higher than that at the buccal or lingual surface (3.25 °C) (p < 0.001). Generally, TR increased significantly as the size of GG drills or the revolution speed increased (p < 0.05). GG5 drills rotated at 8,000 rpm produced the highest TR (10.85 °C). There was no interaction effect of the GG drill size and the revolution speed on TR (p = 0.272).

CONCLUSION

The highest TR on the external root surface, associated with preparation of a staging platform and produced by using GG drills size-5 rotating at up to 8,000 rpm, was lower than the damaging threshold.

CLINICAL RELEVANCE

A staging platform can be performed by modified GG drills (no 2 to 5) rotating at 8,000 rpm without generating a hazardous TR.