In vitro temperatures produced by a new heated injectable gutta-percha system

The effect of canal preparation on fill length in straight root canals obturated with GuttaCore

INTRODUCTION

A common critique of using thermoplasticized carrier-based obturators is the incidence of overextension. It would be of benefit to clinicians to have a technique for canal preparation that would allow for predictable length control. This study compared straight canals instrumented to a size 40 file using a 0.04 standardized taper preparation (STP) and a varied taper preparation (VTP) by evaluating the extension of GuttaCore (GC) obturators (Dentsply Tulsa Dental, Tulsa, OK).

METHODS

Eighty extracted mature human premolars with single straight canals were randomly divided into 2 experimental groups (n = 40). The STP group was instrumented to size 40/.04 at the working length (WL). The VTP group was instrumented to size 40/.02 at the WL. Both groups were obturated with a size 40 GC obturator. Extension of the material, in relation to the WL, was evaluated and assessed ordinally. Statistically significant differences were determined by a 2-group chi-square test with a 2-sided P value set at P = .05 and a Fisher exact test of equal proportions.

RESULTS

Significant differences in extrusion existed between the STP and VTP groups when controlling for the type of apical preparation (P = .0005). The STP group resulted in a 47.2% incidence of overextension, whereas the VTP group resulted in 10.5% overextension of obturating material.

CONCLUSIONS

The results indicate that when filling straight canals with GC obturators the canal can be instrumented using a varied tapered canal preparation with a low likelihood of overextension.

In vitro evaluation of the thermal alterations on the root surface during preparation with different Ni-Ti rotary instruments

The present study evaluated, in vitro, the temperature alterations on the external root surface during instrumentation with four different rotary systems. A total of 20 extracted human maxillary lateral incisors were instrumented using either the ProFile, MicroMega, Quantec or K³ systems and the thermal alterations on the root surface were recorded by means of three thermocouples attached to the coronal, middle and apical portions of the root. Mean temperature increases no higher than 0.4ºC ± 1.0ºC (ProFile system) were recorded, which indicates that these instruments are safe for the surrounding periodontal tissues.

Clinical and Radiographic Evaluation of Root-canal Obturation with Obtura II

This study evaluated clinical and radiographic healing of 236 root-canal treatments in 131 cases obturated with the Obtura II system. One operator performed all canal preparation and obturation with sealer. A standardized apical-coronal preparation technique instrumented all canals. Clinical symptoms, periodontal condition, and radiographic findings were evaluated at 3, 6, and 12 months. Radiographs taken immediately postobturation were compared to recall radiographs. The level of the final root filling was classified as short (more than 2 mm short of the apex), flush (within 2 mm), or over (beyond) in 12.7%, 81.4%, and 5.9% of cases, respectively. More than 96% of cases were treated successfully by the Obtura II system. Where roots were filled flush, over, or short, lesions healed in 97%, 93%, and 93% of cases, respectively, with no significant differences (p < 0.05). Root filling excess had no impact on the healing process.