Dental Hypotheses

ORIGINAL RESEARCH
Year
: 2022  |  Volume : 13  |  Issue : 2  |  Page : 45--48

Comparison of Fracture Resistance of the Endodontically Treated Roots with Two Sealer Types: An In Vitro Study


Neda Hajihassani1, Soolmaz Heidari2, Mohammad Ghanati3, Navid Mohammadi4,  
1 Department of Endodontics, Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
2 Department of Operative Dentistry, Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
3 General Dentistry, Student Research Committee, Qazvin University of Medical Sciences, Qazvin, Iran
4 Children Growth Research Center, Research Institute for Prevention of Non-communicable Diseases, Qazvin University of Medical Sciences, Qazvin; Researcher, Canada Optimax Access Consulting, Port Coquitlam, BC, Iran

Correspondence Address:
Neda Hajihassani
Dental Caries Prevention Research Center, Qazvin University of Medical Sciences, Bahonar Blvd., Qazvin
Iran

Abstract

Introduction: This study aimed to compare the fracture resistance using a bioceramic sealer and an epoxy resin-based sealer. Materials and Methods: One hundred maxillary central incisors were randomly assigned to three experimental groups: AH Plus sealer using the single-cone technique, AH Plus sealer using the lateral compaction technique, SureSeal Root sealer, and two positive and negative control groups. Then the fracture resistance of the prepared tooth roots was determined. The data were analyzed with one-way ANOVA and Tukey Post Hoc tests. Results: There were statistically significant differences between the five study groups (P < 0.001). There was no significant difference between the negative control and Sureseal groups (P = 0.183). There were significant differences between the SureSeal and AH Plus groups (P < 0.05). Conclusion: SureSeal Root sealer significantly increased the fracture resistance of the teeth compared to AH Plus sealer.



How to cite this article:
Hajihassani N, Heidari S, Ghanati M, Mohammadi N. Comparison of Fracture Resistance of the Endodontically Treated Roots with Two Sealer Types: An In Vitro Study.Dent Hypotheses 2022;13:45-48


How to cite this URL:
Hajihassani N, Heidari S, Ghanati M, Mohammadi N. Comparison of Fracture Resistance of the Endodontically Treated Roots with Two Sealer Types: An In Vitro Study. Dent Hypotheses [serial online] 2022 [cited 2022 Aug 10 ];13:45-48
Available from: http://www.dentalhypotheses.com/text.asp?2022/13/2/45/350786


Full Text



 Introduction



Gutta-percha, as a root filling material, cannot sufficiently strengthen the root against vertical root fractures due to its low modulus of elasticity.[1] Sealers are necessary to seal the space between the dentinal wall and the obturating material. The ability of the sealer to bond to dentin and penetrate the dentinal tubules is an advantage that results in the integrity of the intracanal structure, increasing root fracture resistance.[2] Bioceramic sealers have unique physical properties, including high biocompatibility for periapical cells and low shrinkage and dimensional changes.[3] They are hydrophilic, and their hydroxyapatite component bonds with the dentinal wall.[4] They are premixed, and also they are the best choice in the single-cone obturation technique.[5] SureSeal Root sealer is a calcium silicate-based sealer that requires water for setting. It does not shrink during the setting reaction and exhibits very good physical properties.[6] Epoxy resin-based sealers have easy handling, better wettability of the dentin surface, good sealing, and good dentinal tubule penetration.[7] The single-cone technique in association with bioceramic sealers has been suggested by manufacturers, claiming that they provide a hermetic apical seal. The present study compared the effects of a bioceramic and an epoxy resin-based sealer on the root fracture resistance and two obturation techniques.

 Materials and Methods



The study was approved by the research ethics committee of Qazvin University of Medical Sciences (IR.QUMS.REC.1399.356).

A total of 184 maxillary central incisors, extracted due to severe caries, periodontal diseases, and orthodontic treatment, were collected. Hundred teeth with a round cross section of the root canal and intact root without curvature, resorption, root canal obliteration, and calcification were selected. An optical microscope (Zeiss, Oberkochen, Germany) was used for this purpose. The transverse cross section of each tooth was measured with a digital Vernier (1117-802, Chand Company, Dehli, India) at Cementoenamel Junction (CEJ) to include teeth with almost equal dimensions buccolingually and mesiodistally. After cleaning the residual tissues on the tooth surfaces, radiographs were provided in two horizontal directions to confirm the presence of one root canal and the absence of previous root canal therapy. The teeth were immersed in 0.5% chloramine T solution (Iran Discus, Iran) for 1 week, followed by immersion in distilled water at 4ºC. The tooth crowns were removed at CEJ to achieve a 13-mm root length and were measured with a digital Vernier. A #10 K-file (Mani, Tochigi, Japan) was used to evaluate the patency of the apex. The root canal and working length from the sectioned cross section to the apical were measured with a #10 file. Then, were prepared to the working length with the NiTi ProTaper Universal file system (Dentsply-Malliefer, Switzerland) up to file F3 using an NSK rotary motor (ENDO-MATE DT, Japan) at a 1:16 ratio with speed and torque similar to those recommended by the manufacturer. During the preparation steps, 1 mL of 2.5% NaOCl (Hyponic, Iran) was used for irrigation. To remove the smear layer, 2 mL of 17% EDTA (META BIOMED Co., LTD, South Korea) was used for 3 minutes, followed by 3 mL of 5.25% NaOCl for 1 minute. They were irrigated with distilled water.[8] Finally, the teeth were randomly assigned to three experimental groups and two negative and positive control using WinPepi 11.61 software (http://www.brixtonhealth.com/pepi4windows.html) for randomization.

AH Plus (AHP) (lat) group

AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) was prepared according to the manufacturer’s instructions. A standard #40 gutta-percha point (Diadent Inc., Chang Chang Buch Do, Korea) was used as the master cone and obturated by lateral compaction technique (n = 20).

AHP (single) group

A #40 gutta-percha point with a %4 taper was selected as the master cone. AH Plus sealer after preparation with a Lentulu spiral (Dentsply-Maillefer, Switzerland) was moved into the root canal gently to avoid creating voids and placed up to the working length. Excess gutta-percha was removed at the root canal orifice (n = 20).

Sureseal group

A #40 gutta-percha point with a 4% taper was selected as the main cone. SureSeal Root sealer (Suredent Corp., Gyeonggi-do, South Korea) was injected into the root canal using its special syringe according to the manufacturer’s instructions. The main gutta-percha point was coated with sealer and gently placed within the root canal up to the working length to avoid creating voids (n = 20).

The orifice of canals was sealed with light-cured glass ionomer in the experimental groups.

Positive control group

The root canals were prepared but were not obturated (n = 20).

Negative control group

The samples were not prepared without obturation.

All the samples were incubated at 99% humidity at 37ºC for 1 week (Kavooshmega Co., Iran) (n = 20).

The specifications of the root canal filler were mentioned in the supplementary table (figshare. Dataset: 2022. https://doi.org/10.6084/m9.figshare.19588450.v1).

Fracture resistance test

To simulate the periodontal ligament, 4 mm of the apical area of the roots was covered with 0.2 to 0.3 mm of wax. The samples were vertically placed in prefabricated molds, 20 mm in width, which had been filled with self-cure acrylic resin (Acropars, Marlic, Iran) (Supplementary Figure: figshare. Figure: 2022 https://doi.org/10.6084/m9.figshare.19596940.v1), with 4 mm of the root within the acrylic resin and 9 mm of the root out of the acrylic resin. Immediately after the polymerization of acrylic resin began, the samples were retrieved from the acrylic resin, and the wax layer was separated from the roots and covered with a thin layer of polyvinyl siloxane (Panasil, Kettnbach, Germany) and placed again within the acrylic resin. After complete polymerization of the acrylic resin, the samples were placed in a universal testing machine (Zwick-Roel, utm, Z050, Germany) for the compressive test. To carry out the fracture resistance test, the acrylic resin blocks were placed on the lower plate of the machine. The force was applied at a right angle to the root surface at a rate of 1 mm/min until the samples fractured.

Data analysis

One-way ANOVA and Tukey post hoc test were used to analyze results by a blinded data analyst using the Python 3.10.4 (The Python Software Foundation, https://www.python.org).

 Results



Results related to the fracture resistance test among the five study groups are presented in Figure [Figure 1]. There were statistically significant differences between the five study groups (P < 0.001).{Figure 1}

 Discussion



Sureseal bioceramic sealer exhibited the highest fracture resistance among all the experimental groups. Bioceramic sealers contain calcium phosphate, which improves the sealer properties during the setting reaction.[9] The exact mechanism of the bonding of bioceramic sealers to dentin is still unknown. This material is precipitated between the collagen fibers and forms an inorganic nucleus, creating a surface layer with dentin properties.[8] In the presence of dentin moisture, calcium silicate is converted to calcium silicate hydrogel. Subsequently, the relative reaction of phosphate with calcium silicate hydrogel and calcium hydroxide leads to the production of hydroxyapatite, a crystalline structure similar to dentin.[10] Bonding of bioceramic sealers to dentin creates a monoblock and uniform structure between the root canal filling material and the dentinal wall, which improves the fracture resistance of the obturated root canal.[11]

The AH Plus resin sealer group exhibited higher fracture resistance than the control group; therefore, the AH Plus sealer increases the fracture resistance of the tooth.

Owing to the penetration of the dentinal tubules, some studies have shown that the AH Plus sealer exhibits better penetration into the dentinal tubules due to its creeping property and long setting time; therefore, it increases the fracture resistance of the root.[2],[12] In this study, the fracture resistance of the roots obturated with the SureSeal was significantly higher than the AH Plus. In Sarhan’s et al.[13] study, SureSeal had much deeper penetration into the dentinal tubules in all three coronal, middle, and apical areas than the AH Plus sealer, which might be attributed to its high fluidity, small particle size, and low film thickness (19 mm versus 26 mm in the epoxy resin-based sealer).[6],[13],[14] The smaller size of the particles of these sealers is significant[15] in better and deeper penetration of sealers into the dentinal tubules.[16] Bioceramic sealers have smaller particles (less than 2 μm).[14],[17]

Small particles have a high surface-to-volume ratio and are hydrated at a higher rate, resulting in low film thickness, high fluidity, and proper viscosity, which are ideal properties for an obturation material.[8],[18] Also, the hydrophilicity of bioceramic sealers can decrease their contact angle, resulting in deeper penetration of these sealers into the areas of the root canal, with difficult access.[5] The root canal filling materials should have a modulus of elasticity similar to dentin to create a monoblock structure.[19] It is important to select a material that can strengthen the tooth structure against fracture.[8] Owing to the lower elastic modulus of gutta-percha than dentin, the tooth structure is not sufficiently strengthened against vertical root fracture.[1] According to the study by Chakraborty and Basu, the zirconium oxide in the structure of calcium silicate sealers has some special properties, including high fracture resistance, high tensile strength, and low Young’s modulus.[20] The modulus of elasticity of calcium silicate sealers is higher than epoxy resin-based sealers, which are close to dentin, increasing the fracture resistance.[19] AH Plus and gutta-percha don’t form a monoblock structure due to their lower modulus of elasticity than dentin; therefore, they can’t significantly increase the fracture resistance of teeth.[1] In a comparison of the lateral compaction and the single-cone techniques between the AHP (lat) and AHP (single) groups, the latter exhibited higher fracture resistance than the former, but there was no significant difference between the two obturation techniques. Therefore, it might be concluded that the obturation technique cannot significantly increase or decrease the fracture resistance of teeth. Also, using a spreader in the lateral compaction technique may increase stresses on the tooth by the wedging effect, resulting in a decrease in fracture resistance.

 Conclusion



Both sealers increased the fracture resistance compared to unobturated teeth. SureSeal bioceramic sealer significantly increased the fracture resistance compared to the AH Plus sealer. The obturation technique wasn’t effective in fracture resistance.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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