Evaluation of three thermoplasticized gutta-percha filling techniques using a leakage model in vitro

Evaluation of the Quality of Obturation with Obtura at Different Sizes of Apical Preparation Through Microleakage Testing

INTRODUCTION

Obturation of the root canal system is required to prevent recontamination of the root canal after cleaning and shaping procedures and to seal the root canal completely, both the apical and coronal avenues of potential leakage and to maintain the disinfected status.

AIM

The aim of this study was to determine the microleakage by dye leakage method at 1mm, 3mm and 5mm short of the apex with different sizes of apical preparation, obturated by Obtura.

MATERIALS AND METHODS

Sixty freshly extracted human single rooted teeth were randomly distributed into six equal groups. Group I (control group) was obturated by lateral compaction technique. Group II to VI were experimental groups (apical preparations done upto ISO sizes 20, 30, 40, 50 and 60 respectively), obturated by Obtura technique. After storing the samples at 100% humidity for seven days and one day in 2% methylene blue, the roots of the teeth were sectioned at 3mm short of the apex. They were observed under stereomicroscope at 20X magnification and the images were analysed for microleakage using the scoring criteria. The data obtained were analysed by One-way ANOVA followed by Tukey pair-wise multiple comparison test and p ≤ 0.05 was considered as the level of significance.

RESULTS

The lowest mean microleakage score was seen in Group VI (0) and the highest mean leakage score was seen in Group II (1.5). There was statistically significant difference between Group II and Group V (p = 0.044), Group II and Group VI (p = 0.013). There was no significant difference between all the other groups (p> 0.05).

CONCLUSION

Comparison of microleakage between different groups from ISO sizes 20-60 recommends a minimum apical preparation of ISO size 30.

Root canal obturation by ultrasonic condensation of gutta-percha. Part II: an in vitro investigation of the quality of obturation

AIM

To compare the quality of root canal obturation using ultrasonic or cold condensation of gutta-percha and to determine the effect of power setting and activation time on the quality of obturation using the former technique.

METHODOLOGY

An extracted human maxillary canine was used in an in vitro split tooth model to allow repeated obturation of the same root canal system using an ultrasonic device to thermocompact gutta-percha without sealer. After each obturation, the root filling was removed from the tooth to allow evaluation of its quality and for the tooth to be re-obturated. The influence of combinations (n = 10 per combination) of power setting (1, 3, 5) and activation times (4, 10, 15 s) was tested on the quality of root filling, assessed by measuring the voids within the body of the root filling as well as at the surface. Image analysis was used to quantify the voids within the body of the root filling. Cold lateral condensation of gutta-percha served as a control.

RESULTS

Both surface and cross-sectional analyses revealed that different power setting and activation time combinations produced significantly fewer voids than cold lateral condensation (P < 0.05) at the apical, mid-root and coronal levels.

CONCLUSIONS

Taking surface and cross-sectional analysis together only power setting 5 and activation times of 10 and 15 s consistently produced ultrasonically thermocompacted root canal fillings with fewer voids than cold lateral condensation without sealer.

Increased density of gutta-percha using a controlled heat instrument with lateral condensation

The purpose of this study was to compare quantitatively the density of standard cold lateral gutta-percha condensation and warm lateral gutta-percha condensation using the System B heating instrument in a low-heat warm lateral condensation technique in an artificial root canal in vitro. Thirty-degree simulated root canals in 30 transparent acrylic blocks were instrumented using Gates-Glidden burs and Quantec (NT Company, Chattanooga, TN) rotary files. The canals were then obturated with gutta-percha using standard cold lateral condensation without sealer. Warm lateral condensation without sealer using the System B instrument at 101 degrees C was then performed on the same 30 canals. A second treatment of warm lateral condensation was then applied to these same canals. The blocks were weighed after the initial canal preparation and after each obturation treatment. Results showed warm lateral condensation of gutta-percha using the System B resulted in a significant increase in density by weight when compared with standard cold lateral condensation. A 23.97% increase in weight was realized after the first heat application, compared with standard lateral condensation. A second heat application produced an additional 2.59% increase in weight over that produced by the first heat application. Data were analyzed using a t test for repeated measures. Both increases were statistically significant (p < 0.001). Warm lateral condensation using the System B instrument results in denser gutta-percha fills by weight when compared with standard cold lateral condensation.

Current trends in endodontic treatment: report of a national survey

The authors surveyed 360 general dentists and 291 endodontists to obtain information on routine, nonemergency endodontic treatments adapted to clinical practice. Frequent practices and recent advances in treatment modalities-including instrumentation, obturation, intracanal preparations, medications and restorations-are highlighted.

Comparison of the sealing capacity of three endodontic filling techniques

This study compared the sealing capacity of three different endodontic gutta-percha filling techniques. Forty-seven upper central incisors with straight canals were instrumented and randomly divided into three equal groups of 14. An additional group of five teeth with unobturated canals served as positive controls. The following gutta-percha filling techniques were evaluated: Trifecta (group A), lateral condensation (group B), and a combination of SuccessFil gutta-percha and lateral condensation (group C). Tubli-Seal was used as a sealer. The teeth were radiographed in mesiodistal and bucco-lingual directions to study the quality of the filling. Afterward, the teeth were immersed in India ink and subsequently cleared. The maximal depth of penetration was measured using a light microscope. The mean value of ink penetration for group A was 1.073 mm, for group B was 0.522 mm, and for group C was 0.765 mm. No statistically significant differences were seen among groups (p < 0.05).

Improved density of gutta-percha after warm lateral condensation

Simulated straight root canals in 30 transparent acrylic blocks were instrumented and obturated with gutta-percha without sealer using standard lateral condensation (group A). The "zap and tap" method of warm lateral condensation was then used on the same 30 canals (group B). A second treatment of warm lateral condensation was then applied to these same canals (group C). The acrylic blocks were weighed after initial canal preparation and after each subsequent obturation. A 14.63% increase in weight of the gutta-percha occurred in group B compared with group A, and a 2.43% increase in weight occurred in group C compared with group B. Both differences were statistically significant (p < 0.001).

Obturation of a C-shaped canal using an improved method of warm lateral condensation

Pilot studies conducted by the authors seem to indicate that obturation of a root canal system by the lateral condensation of gutta-percha using an electrically heated spreader results in a more homogeneous mass of gutta-percha than standard lateral condensation. This article describes an improved variation which prevents inadvertent dislodgement of the mass of gutta-percha during the obturation. The authors refer to this technique as "zap and tap" and a case report describes its use to obturate a C-shaped canal system of a mandibular second molar.

Evaluation of the dimensional stability of different thermoplasticized gutta-percha fillings using simulated glass root canals

The dimensional stability of different thermoplasticized gutta-percha fillings was analyzed using simulated glass canals. For comparison, gutta-percha fillings obtained with the cold lateral condensation technique was used. The evaluation was done at 0 min, 2 min, 5 min, and 30 min after the filling was completed. The general analysis showed statistically significant differences between 0 min and 5 min-30 min recordings. No significant differences were found between 0 min and 2 min, and between 2 min, 5 min, and 30 min. Although warm lateral condensation resulted in a poor obturation, it was the only thermoplasticized technique analyzed that did not produce significant volumetric changes between 0 min and 30 min. All the other thermoplasticized filling techniques showed important shrinkage during cooling.

Master core apical movement during compaction: evaluation of two in vitro models

This study evaluated two in vitro models (a split hard metal model and a split natural tooth model) for the assessment of master cone apical movement. Gutta-percha cones were fitted 0.5 and 1.0 mm short of the apical ends of the artificial canals. Photographs were taken before and after vertical or lateral compaction and measurements were made. The results demonstrated no significant difference between the two models.

A comparison of thermoplasticized injectable gutta-percha obturation techniques

This study compared the quality of obturation of high- and low-temperature thermoplasticized injectable gutta-percha techniques and standard lateral condensation. A new model system was developed to more closely simulate the clinical environment. All obturations were performed in this same model which allowed direct comparisons between the different techniques. The resultant mass of gutta-percha was visually examined and graded for each obturation. Statistical analysis of the results indicated that both thermoplasticized injectable techniques were significantly better than lateral condensation. There was no significant difference between either of the thermoplastic obturation techniques.

In vivo findings associated with heat generation during thermomechanical compaction of gutta-percha. 1. Temperature levels at the external surface of the root

Temperature elevations of 10 degrees C above body temperature, of duration greater than 1 minute, may be sufficient to cause bone tissue injury. Temperature rises on the root surface in excess of 10 degrees C have been shown in studies in vitro of thermoplasticized gutta-percha root filling techniques. To determine whether results in vitro at room temperature could be extrapolated to conditions in vivo, temperature elevations were recorded at the mid-point on the root surface of the canine tooth in the ferret during thermomechanical compaction of gutta-percha. The time taken for the temperature to return to normal was also measured. There was no statistically significant difference between temperature elevations recorded in vitro and those measured in vivo. A linear extrapolation may therefore be made from results recorded at room temperature. Temperature elevations dissipated more rapidly in vivo than in vitro; this may be due to the cooling effect of the microvasculature of the periodontal membrane.