Comparison of a warm gutta-percha obturation technique and lateral condensation

The imaging of root canal obturation using micro-CT

AIM

To examine the potential and accuracy of micro-computed tomography (micro-CT) for imaging of filled root canals.

METHODOLOGY

The root canals of five extracted maxillary teeth were shaped manually with K-files. After irrigation and drying, the root canals were filled by lateral condensation using gutta-percha cones and AH plus (Dentsply Maillefer, Ballaigues, Switzerland) as sealer. The filled root canals were examined by micro-CT at resolutions <11 microm. Three-dimensional reconstructions of the root canal fillings were made. The roots were sectioned histologically and standard photographs of the sectioned surfaces were taken. Digitized photographic images and the corresponding micro-CT sections were correlated qualitatively by superimposition. Quantitative morphometric data were obtained with respect to the surface area of the root canal filling and the individual gutta-percha points of the histological and the micro-CT sections. Pearson correlation coefficients were calculated.

RESULTS

There was a good qualitative correlation between the images from the histological and the micro-CT sections. The fillings were clearly differentiated from the root canal walls. Individual gutta-percha cones and sealer were discernable. Pearson correlation coefficients showed a highly significant correlation between the two methods (P < 0.001) with respect to the area of the complete root canal filling (r = 0.992) and the gutta-percha cones (r = 0.968).

CONCLUSIONS

The micro-CT technique was a highly accurate and nondestructive method for the evaluation of root canal fillings and its constituents. Qualitative and quantitative correlation between histological and micro-CT examination of root canal fillings was high.

Outcome of root canal treatment using Thermafil and cold lateral condensation filling techniques

AIM

To evaluate the outcome of root canal treatment (RCT) using either Thermafil (TF) or lateral condensation (LC) as filling technique, and to compare the time required for the treatment when either filling technique was used.

METHODOLOGY

This study involved all patients attending the dental clinic of a university in Hong Kong who required primary, nonsurgical RCT. It was a prospective clinical trial involving 85 teeth in 79 patients aged 15-69 years (mean 48 +/- 12 years), which required root treatment and finally filling with either TF or LC by one of four dentists following a standard treatment protocol. The time used for the entire course of treatment was recorded. The treated teeth were examined both clinically and radiographically 3 years after the treatment by a single examiner who did not know their group assignment.

RESULTS

A total of 85 teeth from 79 patients were included in this study and 71 teeth from 64 patients were examined after 3 years. Thirty-four teeth were root filled with LC and 37 with TF. The overall attrition rate was 16% (14/85). There were 22 incisors and canines, 21 premolars and 28 molars for evaluation. Post-treatment disease with clinical symptoms and/or radiographic radiolucency was observed in seven teeth (21%) of the LC group and in seven teeth (19%) in the TF group. There was no statistically significant difference (P > 0.05) for the presence of disease between the two groups. It was found that irrespective of the filling method used, teeth later restored with extracoronal restorations had a lower association with disease than those receiving intracoronal restorations (7% vs. 30%; P = 0.037). RCT took, on average, 20 min less when TF was used for filling compared with LC (98 min vs. 78 min, P = 0.003).

CONCLUSIONS

Using TF or LC in the filling of root canals did not result in significant difference in the clinical treatment outcome. TF consumed significantly less time than LC. The type of postendodontic restoration had a significant association with the presence of post-treatment disease.

Apical Extrusion of Thermoplasticized Obturating Material in Canals Instrumented with Profile 0.06 or Profile GT

The purpose of this in vitro study was to compare the extrusion of thermoplacticized gutta-percha in teeth instrumented with Profile 0.06 or Profile GT, and obturated with Thermafil Plus and Thermafil GT, respectively. A total of 120, extracted, human maxillary central incisors were divided into four equal groups. Group 1 was instrumented with Profile 0.06 and obturated with Thermafil Plus. Group 2 was instrumented with Profile 0.06 and obturated using warm vertical condensation (negative control). Group 3 was instrumented with Profile GT and obturated with Thermafil GT. Group 4 was instrumented with Profile GT and obturated like Group 2 (negative control). Extrusion was graded as present or absent. Results found 9 of 30 extruded for group 1, 1 of 30 for group 2, 15 of 30 for group 3, and 2 of 30 for group 4. The results suggest that, in vitro, Thermafil GT may be more prone to extruding gutta-percha past the apical foramen than Thermafil Plus.

Evaluation of Apical Filling After Warm Vertical Gutta-Percha Compaction Using Different Procedures

The aim of the present study was to evaluate the quality of endodontic sealing in the apical 4 mm of narrow and curved canals using different filling techniques. Human teeth were selected and assigned to four different techniques: group A, Schilder's warm vertical condensation; group B, Schilder's technique modified by using an electric heater; group C, Schilder's technique modified by compaction of the apical tract at body temperature; and group D, a modified vertical compaction with apical back-filling. A dye penetration test was performed, and specimens of group D showed increased apical sealing and reduced extension of voids. The use of the vertical compaction with apical back-filling technique allowed the creation of an effective apical plug and an excellent adaptation of back-filling to apical gutta-percha and to root canal walls.

The effect of insertion rates on fill length and adaptation of a thermoplasticized gutta-percha technique

The purpose of this in vivo study was to determine the effect of the insertion rate of a thermoplasticized gutta-percha obturation technique (Thermafil Plus) on the quality of the root canal obturation. A calibrated practitioner obturated the tooth in each of three groups with insertion rates of 18, 6, and 3 mm/s, respectively. The quality of the obturation was assessed by measuring the length of fill and the replication of induced canal irregularities, consisting of dimples and grooves. All measurements were made on a single tooth, with a working length of 18 mm from the canal orifice, embedded in a split mold, with 20 measurements for each insertion rate. Measurements were made under a low-power microscope, with the images recorded on videotape. The length of fill decreased with decreasing the insertion rate, from a mean overextension of +0.88 mm (SD 1.12 mm) for the 18 mm/s rate to a mean underfill of -0.13 mm (SD 1.03 mm) for the 3 mm/s rate. A trend of decreasing fill with decreasing insertion rate was observed, with the difference between the insertion rates of 18 mm/s and 3 mm/s being statistically significant at p < 0.05 using a single comparison test. Replication of dimples decreased with decreasing the insertion rate from a mean reproduction of 99% for the 18 mm/s rate to a mean reproduction of 90% for the 3 mm/s rate. The replication of grooves also decreased with decreasing the insertion rate from a mean reproduction of 100% for the 18 mm/s rate to a mean reproduction of 88% for the 12 mm/s rate. Statistical analysis of the data for both the dimples and the grooves using a paired comparison post hoc Scheffe test found these differences are significant at p < 0.05.