Push-out bond strength of Resilon/Epiphany self-etch and gutta-percha/AH26 after different irrigation protocols

What Are the Chances of Resilon to Dominate the Market Filling Materials for Endodontics?

This paper is a literature review with additional virtual analyses of the authors’ own experimental research results. Knowledge from various areas was synergistically combined, appropriately for concurrent engineering, presenting several possible methodological approaches used in research, optimizing the selection of engineering materials and the conditions of their application with particular application in endodontics. Particular attention was paid to the theoretical aspects of filling material strengths, weaknesses, opportunities, and threats SWOT analysis. Attention was paid to the original concepts of Sustainable Dentistry Development in conjunction with Dentistry 4.0, which includes endodontics as an important element. The dentists’ actions, among others, in conservative dentistry, along with endodontics, requires close cooperation with engineers and the enginering sciences. Methods of root canal preparation were described, together with selected tools, including those made of nitinol. Principles concerning the process of cleaning and shaping the pulp complex are presented. The importance of obturation methods, including the Thermo-Hydraulic-Condensation THC technique, and the selection of filling materials with the necessary sealants for the success of endodontic treatment are discussed. The experimental studies were carried out in vitro on human teeth removed for medical reasons, except for caries, for which two groups of 16 teeth were separated. After the root canal was prepared, it was filled with studs and pellets of a filling material based on polyester materials, which has gained the common trade name of resilon or, less frequently, RealSeal (SybronEndo) with an epiphany sealant. The teeth for the first group were obturated by cold lateral condensation. In the second case the obturation was performed using the Thermo-Hydraulic-Condensation technique using System B and Obtura III. The experimental leakage testing was done using a scanning electron microscope SEM and a light stereoscopic microscope LSM, as typical research tools used in materialography. The research results, in a confrontation with the data taken from the literature studies, do not indicate the domination of resilon in endodontics.

Virtual Approach to the Comparative Analysis of Biomaterials Used in Endodontic Treatment

The importance of endodontics is presented within our own concept of Dentistry Sustainable Development (DSD) consisting of three inseparable elements; i.e., Advanced Interventionist Dentistry 4.0 (AID 4.0), Global Dental Prevention (GDP), and the Dentistry Safety System (DSS) as a polemic, with the hypothesis of the need to abandon interventionist dentistry in favour of the domination of dental prevention. In view of the numerous systemic complications of caries that affect 3−5 billion people globally, endodontic treatment effectively counteracts them. Regardless of this, the prevention of oral diseases should be developed very widely, and in many countries dental care should reach the poorest sections of society. The materials and methods of clinical management in endodontic procedures are characterized. The progress in the field of filling materials and techniques for the development and obturation of root canals is presented. The endodontics market is forecast to reach USD 2.1 billion in 2026, with a CAGR of 4.1%. The most widely used and recognized material for filling root canals is gutta-percha, recognized as the “gold standard”. An alternative is a synthetic thermoplastic filler material based on polyester materials, known mainly under the trade name Resilon. There are still sceptical opinions about the need to replace gutta-percha with this synthetic material, and many dentists still believe that this material cannot compete with gutta-percha. The results of studies carried out so far do not allow for the formulation of a substantively and ethically unambiguous view that gutta-percha should be replaced with another material. There is still insufficient clinical evidence to formulate firm opinions in this regard. In essence, materials and technologies used in endodontics do not differ from other groups of materials, which justifies using material engineering methodology for their research. Therefore, a detailed methodological approach is presented to objectify the assessment of endodontic treatment. Theoretical analysis was carried out using the methods of procedural benchmarking and comparative analysis with the use of contextual matrices to virtually optimize the selection of materials, techniques for the development and obturation of root canals, and methods for assessing the effectiveness of filling, which methods are usually used, e.g., in management science, and especially in foresight research as part of knowledge management. The results of these analyses are presented in the form of appropriate context matrices. The full usefulness of the research on the effectiveness and tightness of root canal filling using scanning electron microscopy is indicated. The analysis results are a practical application of the so-called “digital twins” approach concerning the virtual comparative analysis of biomaterials used in endodontic treatment.

Comparative Evaluation of Retreatability of Endodontically Treated Teeth using AH 26, Fluoride Varnish and Mineral Trioxide Aggregate-based Endodontic Sealers

Background and Objectives:

Endodontic sealers are used to fill the gap between the root filling material and canal walls. Retrievability is an important requirement for sealers and root filling materials in non-surgical endodontic retreatment. This study sought to assess the retreatability of fluoride varnish, AH 26 and Mineral Trioxide Aggregate (MTA)-based sealers using Cone-Beam Computed Tomography (CBCT).

Materials and Methods:

This in vitro, experimental study evaluated 45 extracted single-rooted, single-canal human mandibular premolars. Teeth with cracks or fracture were excluded. The root canals were prepared using ProTaper Universal rotary system up to size F4 according to the manufacturer’s instructions. The teeth were then randomly divided into three groups of 5% fluoride varnish, AH 26 and MTA Fillapex. CBCT scans were obtained of the teeth with 200 μm voxel size. MATLAB R2012 software was used to quantify the amount of sealer remaining in the canal. Two observers evaluated the images. Data were analyzed using SPSS via the Kruskal-Wallis and Mann Whitney tests.

Results:

The amount of sealer remaining in the root canals was significantly different among the three groups (P<0.05). The amount of AH 26 sealer remaining in the root canals (1.91±1.46) was significantly greater than MTA Fillapex (0.62±0.26) and fluoride varnish, but the latter two were not significantly different in this respect (P>0.05).

Conclusion:

Considering the adequate adhesion of fluoride varnish to dentin, its cariostatic effect and low cost, it seems to be a suitable alternative to the commonly used endodontic sealers.

Design Variability of the Push-out Bond Test in Endodontic Research: A Systematic Review

INTRODUCTION

There is limited literature on the impact of testing variables on the push-out bond test (POBT). This review identified designs of the POBT used in the endodontic literature and aimed to determine which experimental variables may influence the push-out bond strength (POBS).

METHODS

A systematic review based on PRISMA guidelines was performed by searching the PubMed, SCOPUS, and Cochrane library databases using terms including push-out and dislocation resistance and descriptions of endodontic materials. Test variables assessed included method of root preparation, timing of sectioning compared with filling, thickness, diameter and taper of sections, and plunger size and velocity. The POBS of 3 common materials (gutta-percha and AH Plus, mineral trioxide aggregate, and Biodentine) were collected from investigations, and a comparison was attempted.

RESULTS

One hundred thirty-three studies assessed the POBS of root-filling materials, 68 assessed root repair cements/root-end filling materials, and 16 assessed orifice barrier materials other than mineral trioxide aggregate. There was significant variation in all of the assessed variables, resulting in a large range of reported values for the POBS of the various materials. Because of this heterogeneity in study design, no further statistical analysis of the impact of the test variables on POBS was possible.

CONCLUSIONS

There was considerable variation in the POBT design used in endodontic research. Greater standardization is required for future research as well as accurate reporting for all test variables to assess the impact of specific design variables on POBS.

Influence of a calcium hydroxide-based intracanal dressing on the quality of the root canal filling assessed by capillary flow porometry

OBJECTIVE

The objective of this study is to evaluate the influence of a calcium hydroxide intracanal dressing (CH) on the short- and long-term sealing ability of the root canal filling using capillary flow porometry (CFP).

MATERIALS AND METHODS

To verify the repeatability of the method, five obturated specimens were submitted to CFP. Measurements were repeated three times and compared with the non-parametric Friedman test. Forty-five instrumented palatal roots were randomly divided into three groups. Group 1: specimens were obturated in one step without placement of any dressing. Group 2: CH was placed and removed after 1 week with syringe irrigation before obturation. Group 3: CH was placed and removed after 1 week with ultrasonic activation before obturation. CFP measurements were conducted at 1 week and 6 months after obturation. The inter-group comparisons were performed using the Kruskal-Wallis test and the intra-group comparison over time using the Wilcoxon signed-rank test. Significance level was set at 0.05.

RESULTS

In the five specimens, no difference could be detected between the consecutive measurements for minimum, mean flow, and maximum pore diameter indicating repeatability of the method. No difference in sealing ability could be detected neither between the 3 groups at 1 week and at 6 months nor within each group between the 1 week and the 6 months measurements.

CONCLUSIONS

Placement of a CH did not affect significantly the short- and long-term sealing ability of the root canal filling.

CLINICAL RELEVANCE

The use of an intermediary CH does not negatively influence the quality of the root canal filling.

Effect of photon induced photoacoustic streaming (PIPS) on bond strength to dentine of two root canal filling materials

OBJECTIVES

The aim of this study was to evaluate the effect of photon induced photoacoustic streaming (PIPS) technique in combination with EDTA on bond strength of gutta-percha/AH Plus and Resilon/RealSeal SE root canal fillings to root dentine.

MATERIALS AND METHODS

Forty freshly extracted human maxillary anterior teeth with intact straight roots, were instrumented endodontically with rotating ProTaper instruments and randomly divided into two experimental groups. In group 1 (n = 20), root canals were rinsed for 1 minute with 2 ml of 17% EDTA. In group 2 (n = 20), Er:YAG laser, with a 14 mm long 400 μ diameter tapered PIPS tip, was used for 1 minute with 2 ml of 17% EDTA. The laser parameters used were: 20 mJ per pulse, 15 Hz, 50 microsecond. In each experimental group, half of the root canals (n = 10) were obturated with gutta-percha/AH Plus and other half (n = 10) with Resilon/RealSeal SE. A micropush-out test was performed on sectiond specimens of the filled roots using a universal testing machine and resistance to failure plus failure modes were determined.

RESULTS

Both gutta-percha/AH Plus groups had higher bond strength to root dentin than the Resilon/RealSeal SE groups (P < 0.05). The smear layer removal protocol, with EDTA only or combining PIPS technique with EDTA, had no influence on bond strength of either gutta-percha/AH Plus, or Resilon/RealSeal SE (P > 0.05).

CONCLUSION

Within the limitations of this study, it was found that the application of the PIPS technique did not have an affect on the push-out bond strength of Resilon/RealSeal SE root canal filling to dentin nor on the gutta-percha/AH Plus. A significant difference in bond strength was noted between the two root canal filling materials. Lasers Surg. Med. 48:951-954, 2016. © 2016 Wiley Periodicals, Inc.

In vitro study of the apical microleakage with resilon root canal filling using different final endodontic irrigants

Background

Endodontic microleakage or microfiltration refers to the percolation of fluids and micro-organisms at the interface of the obturation material and the walls of the root canal system. The aim of this in vitro study was to compare apical microfiltration of Resilon root canal filling by employing three different final irrigant solutions.

Material and Methods

128 single-rooted teeth were employed. The crowns were sectioned horizontally at the cemento-enamel junction and instrumented with 5.25% sodium hypochlorite (NaOCl) and 17% EDTA gel to obtain an instrumented 040 apical caliber. An intermediate irrigation was performed with distilled water. The roots were then randomly assigned to three experimental groups with three different final irrigants: (A) 20% citric acid (CA); (B) 2% chlorhexidine digluconate (CHX); and (C) 5.25% NaOCl, plus two control groups (positive and negative). They were then dried, obturated with RealSeal™, and cleared by Robertson’s technique. Apical microleakage was measured by the dye penetration method and assessed with a 4.5x stereomicroscope. Data were statistically analyzed by one way ANOVA and post hoc analysis for multiple comparisons.

Results

Mean and standard deviations for apical microleakage were: 2% CHX (0.24 mm ± 0.22), 20% CA (0.25 mm ± 0.20), and 5.25% NaOCl (0.87 mm ± 0.32). Significant differences were reported among the group irrigated with NaOCl, CHX and CA (P<0.001).

Conclusions

A higher rate of apical microleakage was observed when the final irrigation was performed with NaOCl whilst lower rates were reported for CHX and CA.

Key words:Apical filtration, endodontic irrigation, resin-based sealers, adhesion, root canal filling.

Resilon: Review of a New Material for Obturation of the Canal

Resilon is a thermoplastic synthetic polymer-based endodontic material alternative to gutta-percha. It contains bioactive glass and also radiopaque fillers. It has the same handling properties as gutta-percha. For endodontic retreatment, it may be dissolved with some solvents, such as chloroform or softened with heat. The composition of Resilon and its sealer (Epiphany) bond to dentin and form a monoblock. A review of the literature and a discussion of its properties comparing to other root canal filling materials are presented.

Ethylenediaminetetraacetic acid in endodontics

Ethylenediaminetetraacetic acid (EDTA) is a chelating agent can bind to metals via four carboxylate and two amine groups. It is a polyamino carboxylic acid and a colorless, water-soluble solid, which is widely used to dissolve lime scale. It is produced as several salts, notably disodium EDTA and calcium disodium EDTA. EDTA reacts with the calcium ions in dentine and forms soluble calcium chelates. A review of the literature and a discussion of the different indications and considerations for its usage are presented.

Bond strength to root dentin and fluid filtration test of AH Plus/gutta-percha, EndoREZ and RealSeal systems

OBJECTIVES

To investigate the bond strength and seal ability produced by AH Plus/gutta-percha, EndoREZ and RealSeal systems to root canal dentin.

MATERIAL AND METHODS

Sixty extracted single-root human teeth, instrumented manually to size 40, were divided into three groups (n=20) according to the sealer used; G1: AH Plus, G2: EndoREZ, and G3: RealSeal sealers. After filling using the lateral condensation technique, each sealer group was randomly divided into two subgroups according to the tests applied (n=10 for µPush-out test and n=10 for fluid filtration test). A fluid filtration method was used for quantitative evaluation of apical leakage. Four 1-mm-thick slices (cervical and medium level) were obtained from each root sample and a µPush-out test was performed. Failure modes were examined under microscopy at 40x, and a one-way ANOVA was applied to analyze the permeability. Non-parametrical statistics for related (Friedman's and Wilcoxon's rank tests) or unrelated samples (Kruskal-Wallis' and Mann-Whitney's tests) allowed for comparisons of µPush-out strength values among materials at the different levels. Statistical significance was accepted for p values <.05.

RESULTS

There are no significant differences among fluid filtration of the three sealers. The sealer/core material does not significantly influence the µPush-out bond strength values (F=2.49; p=0.10), although statistically significant differences were detected with regard to root level (Chi2=23.93; p<0.001). AH Plus and RealSeal obtained higher bond strength to intraradicular dentin in the medium root slices.

CONCLUSIONS

There are no significant differences between the permeability and global µPush-out bond strength to root canal dentin achieved by AH Plus/gutta-percha, EndoREZ and RealSeal systems.

Resilon: a comprehensive literature review

Background and aims. An ideal root canal filling material should completely seal the entire root canal space and block communication between the root canal system and its surrounding tissues; it should also be nontoxic, noncarcinogenic, non-genotoxic, biocompatible, insoluble in tissue fluids and dimensionally stable. Bonding to dentin is a promising property, which can prevent leakage and improve the sealing ability of root canal filling materials. Resilon was developed and rec-ommended initially because the existing rootcanal filling materials did not bond to root canal dentin. Since its introduction in 2004, numerous reports have been published regarding various aspects of this material. The aim of this literature review is to present investigations regarding Resilon's physical and chemical properties and leakage studies. Materials and methods. A review of the literature was performed by using electronic and hand searching methods for Resilon from May 2004 to April 2012. Results. There are many published reports regarding Resilon. The searchshowed that Resilon is composed of a parent polymer, polycaprolactone or Tone, which is a biodegradable aliphatic polyester, with filler particles consisting of bioactive glass, bismuth oxychloride and barium sulfate. It possesses some antibacterial and antifungal properties. It is a promising material for root canal filling. Despite the presence of numerous case reports and case series regarding these applications, there are few designed research studies on clinical applications of this material. Resilon has some drawbacks such as high cost. Conclusion. Resilon seals well and is a biocompatible material. However, more clinical studies are needed to confirm its efficacy compared with other materials.

The effects of calcium hydroxide removal methods on bond strength of Epiphany SE with two irrigation protocols

OBJECTIVE

The purpose of this study was to compare the effects of five calcium hydroxide removal methods on the bond strength of Epiphany SE sealer after canal irrigation with NaOCl+EDTA or NaOCl+MTAD.

MATERIALS AND METHODS

The 120 roots were instrumented by using the ProTaper rotary system under irrigation with 2.5% sodium hypochlorite and randomly divided into two major groups according to the final irrigation: 1.3% NaOCl + MTAD and 5% NaOCl + 17% EDTA. For controls, 10 roots from each of the final irrigations with NaOCl + MTAD and NaOCl + EDTA (20 roots) were not filled with Ca(OH)2. The intra-canal paste, Ca(OH)2 was applied to each of the 100 remaining roots and stored at 37°C for 7 days. Each group was sub-divided into five sub-groups (n = 10) according to the removal technique for the intra-canal dressing: Group-1: recapitulation with size 30 K file + 3 ml of saline solution, Group-2: recapitulation with size 30 K file + 3 ml of 5% NaOCl, Group-3: using 5% NaOCl + 17% EDTA, Group-4: using 5%NaOCl + 15% citric acid, and Group-5: using 1.3% NaOCl + 5 ml MTAD. The root canals were filled with Resilon and Epiphany SE sealer. The bond strength was measured.

RESULTS

The mean bond strength of Epiphany SE to root dentine irrigated with NaOCl + MTAD was lower than that of NaOCl + EDTA. The highest bond strengths were 3.31 ± 0.057 and 2.60 ± 0.054 in the NaOCl + citric acid group when Ca(OH)2 was applied to roots treated with NaOCl + EDTA and NaOCl + MTAD, respectively (p < 0.05).

CONCLUSION

For root canals treated with NaOCl + EDTA or NaOCl + MTAD, the use of NaOCl + chelating agent for Ca(OH)2 removal does not adversely affect the bond strength of Epiphany SE to dentin.

Adhesion of real seal to human root dentin treated with different solutions

The aim of this study was to evaluate the effects of different irrigants on sealer-dentin bond strength when using Real Seal. Thirty single-rooted teeth were divided into 3 groups. In one group, the teeth were irrigated with 3 mL of 2.5% NaOCl after each file change, flushed with 17% EDTA for 3 min and finally rinsed with 3 mL of 2.5% NaOCl. In the other two groups, rinse with NaOCl was replaced with 2% chlorhexidine gluconate (CHX) and 0.9% saline, respectively. Each root was sectioned transversally into apical, middle and coronal thirds to obtain 2-mm-thick slices. Each slice was filled with Real Seal and Resilon. Push-out test was used to analyze bond strength and failure modes were classified as adhesive, cohesive or mixed, according to SEM observations. The push-out test did not reveal any statistically significant difference (p>0.05) between the irrigants. However, the groups exhibited significantly different (p<0.05) bond strengths in terms of the root canal third. Higher bond strength was observed at the apical third when compared with coronal third, while middle third presented intermediary values. Fifteen specimens were analyzed by SEM (5 per group). Eleven specimens exhibited adhesive failures (5 in saline, 4 in NaOCl and 2 in CHX group); 2 cohesive failures were observed in the CHX group, and 1 mixed failure each was observed in the CHX and NaOCl groups. The tested irrigants did not influence the bond strength of Resilon and Real Seal to dentin. The apical third exhibited higher mean bond strengths and adhesive failures were predominant.