The percentage of gutta-percha-filled area in simulated curved canals when filled using Endo Twinn, a new heat device source

A critical analysis of research methods and experimental models to study root canal fillings

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11,000 articles, an impressive number that is much higher than "root canal disinfection" (5,544 articles) or even the popular "root canal preparation" (8,527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. Since filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology-based review, this paper aims to present an in-depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long-term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long-term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques.

Ultrasonic vibration and thermo-hydrodynamic technique for filling root canals: Technical overview and a case series

AIM

To present a novel root canal filling technique: Ultrasonic Vibration & Thermo-Hydrodynamic Obturation (VibraTHO), and its rationale with a series of cases.

SUMMARY

The VibraTHO technique was used to fill the root canals of three clinically challenging cases: A C-shaped mandibular molar with complex anatomy, a C-shaped mandibular molar with an infected root canal system and a periapical lesion that required retreatment, and apically bifurcating mesiobuccal canals with a common orifice in a maxillary second molar. The cases were followed up for 15, 7 and 37 months, respectively. After follow-up, normal periapical status was observed without any noticeable radiographic change in the root canal fillings in each case. Periapical radiographs revealed complete healing of the periapical area in cases with pre-operative periapical lesions.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique

OBJECTIVES

The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1.

MATERIALS AND METHODS

Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth.

RESULTS

Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region.

CONCLUSIONS

These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system.

CLINICAL RELEVANCE

These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

System B, Endo-Twinn and E-Fill. True temperatures inside the canal

Background:

The aim of this study is to verify the variations of the temperature inside the root canal with three different gutta-percha heating systems.

Materials and Methods:

A split-tooth model was built with a lateral groove at 3.5-mm from working length (WL) in order to insert a Chromel-Alumel K-type thermocouple placed in contact with gutta-percha. The thermocouple was connected to a digital thermometer. Sixty obturations were made with medium gutta-percha points. For 20 specimens the System B was used with the Buchanan fine plugger and the temperature was set at 200°C; for other 20 specimens the Endo-Twinn with a fine plugger was used and for the last 20 specimens we used the E-Fill with a 40.04 plugger. All pluggers were pushed to 3.5 mm from WL so that the tips were in contact to the probe.

Results:

The analysis of 60 samples showed the highest temperature average using the System B after 10 seconds (86.85°C), after 15 seconds (94.9°C), after 20 seconds (100.4°C) and after 25 seconds (104.5°C). The Endo-Twinn average values are similar to System-B ones. The E-Fill average values are lower (69.9°C) than the other two systems evaluated only after 10 seconds due to limited working time. The temperatures average obtained using different systems of warm vertical compaction are lower than what was declared by the producing companies.

Conclusion:

Time is one the most important parameters to consider using these systems. Temperatures reached from the System B and Endo-Twinn after 25 seconds; however, seem to be sufficient to ensure an optimal adaptation of the gutta-percha in the anatomical complexity of root canals. The temperatures obtained from the E-Fill, only after 10 seconds, instead seems to be insufficient to assure the rheological characteristics of gutta-percha.

A comparative evaluation of gutta-percha filled areas in curved root canals obturated with different techniques

The aim of this study was to compare different obturation techniques in severely curved canals in terms of the percentage of gutta-percha filled area and voids. The obturation times and the incidence of extrusion of filling material were also compared. Curved root canals (curvature, 25-35°) of 48 extracted human teeth were enlarged with Mtwo rotary NiTi instruments and obturated as follows: Group A: 0.04/35 matched-single-cone; Group B: cold lateral compaction with 0.04/35 gutta-percha master cone; Group C: warm vertical compaction; Group D: lateral compaction with standardized gutta-percha master cone. In all groups AHPlus was used as sealer. The teeth were sectioned horizontally at 2, 3, 4, 6 and 8 mm from the apex. The total area of each canal segment was measured and the areas of gutta-percha, sealer and voids were converted to percentages of the total area. Data were subjected to the Kruskal-Wallis and post hoc Dunn test. Obturation times were compared using ANOVA and post hoc Student-Newman-Keuls test. The matched-single-cone obturation (group A) was significantly the fastest method while warm vertical compaction (group C) required significantly more time than all other techniques (p < 0.05). No significant differences were obtained between the groups in terms of percentage of voids at any level (p > 0.05). At all levels, groups B, C, and D produced significantly higher gutta-percha filled areas (p < 0.05) and lower sealer-filled areas (p < 0.05) than group A. No significant differences were found between groups B, C, and D (p > 0.05) regarding gutta-percha and sealer-filled areas. Within the limitations of the in vitro study, it can be concluded that lateral compaction of greater taper gutta-percha cones is a fast and efficient method for obturation of curved canals.