Investigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source

doi:10.1016/j.joen.2013.09.026

Journal of Endodontics

Volume 40, Issue 4, April 2014, Pages 555-561

https://doi.org/10.1016/j.joen.2013.09.026 Get rights and content

Abstract

Introduction

During warm vertical compaction of gutta-percha, root canal sealers with different chemical compositions absorb the heat generated inside the root canal. The aim of this research was to assess physicochemical modifications of sealers subjected to the System B heat source (Analytic Technology, Redmond, WA) and to evaluate the effect that the use of different sealers has on the heat transfer to the external root surface.

Methods

Three proprietary brand sealers (AH Plus [Dentsply International, Addlestone, UK], Pulp Canal Sealer [Kerr Corporation, Orange, CA], MTA Fillapex [Angelus Dental Solutions, Londrina, PR, Brazil]) and a prototype sealer based on Portland cement were assessed. The heat generated on the surfaces of System pluggers and the heat dissipation at different levels (apical, midroot, and cervical) over root surface while using different sealers was assessed using thermocouples. Data were collected in 3 different environmental conditions with the tooth suspended in air, immersed in Hank's balanced salt solution, or gelatinized Hank's balanced salt solution. Chemical changes in the sealers induced by the heat were monitored by Fourier transform infrared spectroscopy. The effect of heat changes on the setting time and compressive strength of the sealers was also assessed.

Results

The continuous wave plugger sustained a rise in temperature at a maximum of 80°C at the instrument shank. The highest change in temperature on the external root surface was recorded after 1.5 minutes from the start of heating, and it was restored to body temperature by 6 minutes. Environmental conditions affected heat dissipation for all the sealers in the midroot and cervical regions and the highest increase in temperature (∼60°C) recorded in air. In the midroot and cervical regions, the type of sealer used did not affect the rise in temperature. In the apical region, AH Plus obturations resulted in a greater rise in temperature, and the chemical composition of this sealer was affected by high temperature; it also induced a reduction in sealer setting time and strength.

Conclusions

It could be concluded that surrounding conditions, such as temperature and humidity, exerted influence on heating dissipation during the continuous wave of the condensation obturation technique and that root canal sealers presented different conductive/isolating properties. Furthermore, the physical and chemical properties of AH Plus were negatively affected by the changes in temperature.

Section snippets

Materials and Methods

The materials used in this study included the following conventional sealers and an experimental root canal sealer: AH Plus (Dentsply International, Addlestone, UK), MTA Fillapex (Angelus Dental Solutions, Londrina, PR, Brazil), Pulp Canal Sealer (Kerr Corporation, Orange, CA), and Prototype Sealer (Araraquara Dental School, São Paulo State University, Brazil).

AH Plus, MTA Fillapex, and Pulp Canal Sealer sealers were manipulated according to manufacturers' instructions. Prototype Sealer was

Analysis of Heat Produced by System B

The temperatures recorded at different levels along the surface of the System B continuous wave plugger are shown in Figure 2A. The temperature of the continuous wave plugger rose immediately upon application of heat. Once the System B was switched off, the plugger cooled in 30 seconds. The tip of the plugger and the middle part of the instrument sustained a rise in temperature to a maximum of 50°C, whereas the shank of the System B plugger exhibited the highest rise in temperature with a

Discussion

Obturation techniques performed with thermoplasticized gutta-percha result in a temperature rise on the external root surface, which can potentially cause irreversible damages to the surrounding tissues (25). Specific devices such as thermistor (26), infrared cameras 18, 21, finite element analysis 22, 23, and thermocouples 1, 11, 16, 17, 18, 20, 27 have been used to measure the heat generated inside the root canal and dissipated to the interconnecting periodontium and bone. In the current

Acknowledgments

The authors thank Mr N. Azzopardi of the Department of Civil and Structural Engineering, Faculty for the Built Environment and Mr J. Spiteri of the Department of Chemistry, Faculty of Science, University of Malta for their technical expertise.

Supported by “Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP - 2010/10769-1 and 2010/17976-2)” and the University of Malta Research Grant Committee.

The authors deny any conflicts of interest related to this study.

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Final root canal irrigation should ideally maintain the physicochemical stability of root canal sealers. We seek to assess the effect of contact with 2% chlorhexidine digluconate (CHX) on the physicochemical properties of AH Plus, BioRoot™ RCS, and Pulp Canal Sealer (PCS).
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Evaluation of the Physicochemical and Biological Properties of EndoSequence BC Sealer HiFlow
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Citation Excerpt :
Therefore, in order to simulate a clinical scenario, in addition to normal body temperature (37°C), we also investigated how an increase in temperature would influence the setting time of sealers. During warm vertical obturation procedures, heat is applied with a carrier set to 200°C, although the actual carrier temperature has been reported to be around 100°C6,9,22. Our results showed that at 37°C, the final setting time was approximately 17 hours for AHP and 55 hours for BC and BCH, which is a 223% increase in comparison with AHP.
Understanding the physicochemical and biological properties of endodontic sealers is important for endodontic treatment planning. This study evaluated the properties of EndoSequence BC Sealer HiFlow (BCH; Brasseler USA, Savannah, GA), EndoSequence BC Sealer (BC, Brasseler USA), and AH Plus (AHP; Dentsply DeTrey, Konstanz, Germany). The effect of temperature on the setting time and flow of these sealers was also evaluated.
The setting time, flow, radiopacity, pH, solubility, and calcium release were investigated following ISO guidelines. The morphology and chemical composition of the sealers were evaluated by scanning electron microscopy and energy-dispersive spectroscopy. The antibacterial activity of sealers was tested against 2 strains of Enterococcus faecalis. Sealer cytotoxicity and the effects on messenger RNA expression of proinflammatory and mineralization genes were also investigated. Data analysis was performed using analysis of variance, Tukey, Kruskal-Wallis, and Dunn multiple comparison tests. P ≤ .05 was considered statistically significant.
The setting time and flow rate of all sealers were affected by heat (P ≤ .05). The setting times and solubility of BCH and BC were significantly higher than AHP (P ≤ .0001). The radiopacity of AHP was higher than BCH and BC (P ≤ .0001). All sealers were alkaline and had antibacterial effects. Cell viability was higher for BCH and BC than AHP (P ≤ .0001). No significant differences in messenger RNA expression of proinflammatory and mineralization genes were observed.
Overall, BCH and BC had similar physicochemical and biological properties. The observed high solubility of BCH and BC as well as the high cytotoxicity of AHP might negatively impact the clinical performance of these materials. The application of heat affected the setting time and flow of all sealers.
Antimicrobial and physicochemical characterization of endodontic sealers after exposure to chlorhexidine digluconate
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Assess the antibacterial, physical and chemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) in contact with 2% chlorhexidine digluconate (CHX) used as final irrigant prior to root canal obturation.
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CHX increased the antibacterial activity of all the sealers investigated against planktonic bacteria and biofilms with PCS exerting the highest antimicrobial activity with and without the presence of CHX. The setting of AH Plus and BioRoot RCS was retarded, while for PCS accelerated in the presence of CHX. AH Plus and PCS were more hydrophilic after contact with CHX, whilst BioRoot RCS was hydrophobic in a time-dependent manner. The microhardness of sealers was compromised and the surface roughness increased after CHX exposure for AH Plus and BioRoot RCS, and decreased for PCS. CHX did not affect the sealers’ chemistry, but PCS that exhibited two extra phases.
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The heat carriers exhibited a different heat output to the setting on the dial. This has been reported previously [5,6,8,26] and is a cause of concern since the temperature cannot be controlled. In accordance with previous research, the highest temperatures were generated at the coronal aspect of the root canal [5] and the temperatures of the heat carriers recorded inside the root canal ranged from 45 to 70 °C [7].
Warm vertical compaction of gutta-percha is a technique that is used by most specialists for root canal obturation. The sealers currently available exhibit irriversible chemical changes when heated. New biologically active sealers that do not sustain irreversible changes when heated are an attractive alternative to be used with warm vertical compaction obturation technique. The aim of this study was to measure the heat generated by warm vertical compactors inside the root canal, characterize a newly developed root canal sealer at different temperatures and verify its suitability at the actual temperature window used clinically.
The typical temperatures generated by two heat carriers in a root canal were assessed by thermocouples. Two premixed root canal sealers TotalFill BC and HiFlow BC (FKG, Switzerland) were allowed to set and they were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD) immediately after setting and by XRD after 28 days in physiological solution. The ion leaching in solution was assessed by inductively coupled plasma (ICP). The organic component was extracted in acetone and assessed by Fourier transform infrared spectroscopy (FT-IR) for both the unset sealer and sealer subjected to different temperatures. The heat profiles of both sealers were investigated by FT-IR and thermographic analysis.
None of the devices tested achieved the temperatures set on the dial. The highest temperatures were coronal followed by apical for both devices. The sealers were identical except for the vehicle. The inorganic components included tricalcium silicate, dicalcium silicate and zirconium oxide. No calcium hydroxide was produced by any of the sealers after immersion in physiological solution but calcium was released in solution. The chemistry of both sealers was modified when heated but both recovered when cooled.
The heat carriers were unreliable and the heat generated inside the canal was not the same as the temperature set on the dial. Since both sealers had identical chemistry save for minimal modifications to the organic component and were both resistant to heat, TotalFill BC sealer is recommended for use with warm vertical compaction technique as it is cheaper and as effective as the HiFlow.
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Basic ResearchInvestigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source

Abstract

Introduction

Methods

Results

Conclusions

Section snippets

Materials and Methods

Analysis of Heat Produced by System B

Discussion

Acknowledgments

J Endod

Dent Clin North Am

J Endod

J Endod

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Endod

J Prosthet Dent

J Endod

J Endod

J Endod

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Endod

J Endod

Basic Research
Investigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source