Leakage along apical root fillings with and without smear layer using two different leakage models: a two-month longitudinal ex vivo study

In vitro comparative evaluation of apical leakage using a bioceramic sealer with three different obturating techniques: A glucose leakage model

Context

Bioceramic sealers have improved sealing ability by forming an interfacial apatite layer that chemically bonds the sealer and radicular dentin thus decrease apical leakage.

Aim

This study aims to evaluate and compare the apical leakage of Cerafill RCS bioceramic sealer and gutta percha when used with three different obturating techniques.

Materials and Methods

Thirty-four extracted single-rooted premolars were decoronated and prepared up to size F3. Then, the specimens were randomly divided into 3 experimental groups (n = 10) cold lateral obturation technique, warm vertical obturation technique, single-cone obturation technique, positive and negative control groups (n = 2), according to the obturation technique used along with a bioceramic sealer. To evaluate apical leakage, all specimens were mounted in a glucose leakage model and assessed at 7 and 14 days using an ultraviolet-visible spectrophotometer.

Statistical Analysis

The results were subjected to ANOVA/Kruskal-Wallis ANOVA; followed by post hoc analysis using Bonferroni correction.

Results

Significant differences were found in the cumulative leakage of all the three experimental groups. Significantly higher leakage was found in groups obturated using single-cone obturation technique as compared to warm vertical compaction technique at both 7 and 14 days.

Conclusions

Warm vertical compaction showed a better sealing result than single-cone obturation techniques at all observation periods.

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.

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.

A Confocal Microscopic Study on Percentage Penetration of Different Sealers into Dentin

Context:

Three-dimensional seal of the root canal space has always been challenging. The incorporation of gutta-percha and sealer prevents microleakage by bacteria, ensuring a shielded root canal space. However, the penetration of sealer to various depths within the root canal has always been looked with curiosity.

Aims:

Thus, the present in vitro study was undertaken to evaluate the percentage and average depth of penetration of Endoflas F. S., AH Plus, and Epiphany sealers into dentinal tubules among the coronal, middle, and apical thirds of the roots following obturation with a lateral compaction technique using Confocal Laser Scanning Microscopy.

Settings and Design:

The study is an in vitro randomized control trial.

Subjects and Methods:

Thirty sound central incisors were decoronated at the level of the cementoenamel junction. Working length determination was done followed by a meticulous cleaning, shaping, and under copious irrigation. The teeth were then randomly divided into three groups: Endoflas FS sealer, AH Plus sealer, and Epiphany sealer. On fluorescence treatment, the teeth were sectioned at the midpoint of coronal, middle, and apical third of each root and viewed under confocal laser scanning microscope.

Statistical Analysis Used:

The results were analyzed using one-way ANOVA, and the significant difference between groups was analyzed with post hoc Tukey test.

Results:

Epiphany sealer provided with better percentage and depth penetration in comparison to Endoflas FS and AH Plus sealers. Furthermore, the coronal third of the root had better percentage and sealer penetration than the middle and apical thirds.

Conclusions:

Sealers tend to provide a firm bond between the tooth and the gutta-percha. They bind, lubricate, and seal the gutta-percha cones to fill the accessory canals. Within the limitations of this study, the superior flow and enhanced setting time Epihany sealers provide better percentage and depth of penetration than AH Plus and Endoflas FS.

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

The paper is an extensive monographic review of the literature, and also uses the results of the authors’ own experimental research illustrating the noticed developmental tendencies of the filling material based on gutta-percha. The whole body of literature proves the correctness of the research thesis that this material is the best currently that can be used in endodontics. Caries is one of the most common global infectious diseases. Since the dawn of humankind, the consequence of the disease has been the loss of dentition over time through dental extractions. Both tooth caries and tooth loss cause numerous complications and systemic diseases, which have a serious impact on insurance systems and on the well-being, quality, and length of human life. Endodontic treatment, which has been developing since 1836, is an alternative to tooth extraction. Based on an extensive literature review, the methodology of qualifying patients for endodontic treatment was analyzed. The importance of selecting filling material and techniques for the development and obturation of the root canal during endodontic treatment was described. Particular attention was paid to the materials science aspects and the sequence of phase transformations and precipitation processes, as well as the need to ensure the stoichiometric chemical composition of Ni–Ti alloys, and the vacuum metallurgical processes and material processing technologies for the effects of shape memory and superelasticity, which determine the suitability of tools made of this alloy for endodontic purposes. The phenomena accompanying the sterilization of such tools, limiting the relatively small number of times of their use, play an important role. The methods of root canal preparation and obturation methods through cold side condensation and thermoplastic methods, including the most modern of them, the thermo-hydraulic condensation (THC) technique, were analyzed. An important element of the research hypothesis was to prove the assumption that to optimize the technology of development and obturation of root canals, tests of filling effectiveness are identified by the density and size of the gaps between the root canal wall, and the filling methods used and devices appropriate for material research, using mainly microscopy such as light stereoscopic (LSM) and scanning electron (SEM). The most beneficial preparations were obtained by making a longitudinal breakthrough of 48 natural human teeth, extracted for medical reasons, different from caries, with compliance with all ethical principles in this field. The teeth were prepared using various methods and filled with multiple obturation techniques, using a virtual selection of experimental variants. The breakthroughs were made in liquid nitrogen after a one-sided incision with a narrow gap created by a diamond disc using a materialographic cutter. The best effectiveness of the root canal filling was ensured by the technology of preparing the root canals with K3 rotary nitinol tools and filling the teeth with the THC thermoplastic method using the System B and Obtura III devices with studs and pellets of filling material based on gutta-percha after covering the root canal walls with a thin layer of AH Plus sealant. In this way, the research thesis was confirmed.

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.

Dental Adhesive Interfaces Reinforced with Magnetic Nanoparticles: Evaluation and Modeling with Micro-CT versus Optical Microscopy

Dental adhesives are used in a wide range of applications, including to place direct composite restorations in frontal or posterior teeth. One of the most frequent causes for the failure of composite resin restorations is microleakages. The first aim of this work is to introduce a new type of self-etched dental adhesive doped with magnetic nanoparticles (MPs) synthetized in the laboratory. The scope is to produce adhesives with a minimized width/thickness to decrease the risk of microleakages. The second aim is to assess the width/thickness of the adhesive layer in all the characteristic areas of the teeth using both the less precise but most common optical microscopy and the more accurate and volumetric micro-Computed Tomography (CT) investigations. Twenty extracted teeth have been divided into four groups: Group 1 includes 'blank' samples with adhesives that are not doped with MPs; Group 2 includes samples with adhesives doped with MPs; Groups 3 and 4 include samples with adhesives doped with MPs that are subjected to an active magnetic field for 5 and 10 min, respectively. Microscopy investigations followed by micro-CT and EDAX are performed on the adhesive. While a rather good agreement is obtained between the microscopy and micro-CT results, the capability of the latter to offer a full volumetric reconstruction of the layer is exploited to analyze the adhesion of the four considered dental materials. Thus, from micro-CT results the graphs of the surface areas as functions of the adhesive layer width are modeled mathematically, as well as the volume of sealants, for each of the four groups. To our knowledge, it is the first time that such a methodology is used. Characteristic parameters are extracted and the ascertainment of the optimal parameter that should be utilized for such assessments is discussed. The study demonstrates the adhesion improvement produced for Groups 3 and 4, where MPs are used. It also concludes that the magnetic field should be applied to the adhesive material for the longest possible exposure time (with a trade-off with the clinical duration of the treatment).

The Effectiveness of Laser-Activated Irrigation on the Apical Microleakage Qualities of MTA Repair HP and NeoMTA Plus in Simulated Immature Teeth: A Comparative Study

There are limited data regarding the potential effect of erbium, chromium: yttrium–scandium–gallium–garnet (Er,Cr:YSGG) laser-activated irrigation (LAI) on the microleakage qualities of calcium silicate-based cements. The objective of the present study was to assess the effect of LAI on the microleakage qualities of MTA Repair HP (MTA-HP) and NeoMTA Plus (Neo) used in root-end filling and to compare the antimicrobial effectiveness of MTA- HP. Two experimental sets were conducted: antimicrobial activity (agar diffusion test/at 24, 48 h) and microleakage (glucose leakage model/at 1st, 10th, 20th days). Antimicrobial activities of MTA-HP, Neo, Biodentine, ProRoot and MTA Angelus were evaluated, and inhibition zones were observed not only against a range of Gram-positive and Gram-negative bacteria but also against yeast at 48h. For microleakage evaluation, fifty teeth were prepared to simulate the clinical situation where the root-tips (apex) are open, and randomly divided into two experimental groups (n = 20/group) according to the cement type (MTA-HP and Neo), and two control (n = 5/group) groups. Each experimental group was further divided into two subgroups (n = 10/group) with respect to LAI: MTA-HP, L-HP, Neo, L-Neo. A statistical difference was only detected between Neo and L-HP groups on day 1. Subsequently, MTA-HP exhibited superior microleakage quality compared to Neo in the short-term. Er,Cr:YSGG laser-activated irrigation could be used as a reliable technique without creating adverse effects on the sealing abilities of MTA Repair HP and NeoMTA Plus.

Analysis of sealing ability of endodontic cements apical plugs

Background

It is unknown whether the bioactivity of Biodentine characterized by the precipitation of hydroxyapatite and formation of tags into the dentinal tubules improve its sealing ability as an apical plug. Aim: To evaluate the sealing ability provided by Biodentine and mineral trioxide aggregate (MTA) apical plugs, with or without phosphate-buffered saline (PBS) intracanal dressing, using a glucose leakage method.

Material and Methods

The space of the canal of 100 root segments with about 12 mm long was shaped using Gates-Glidden. After created an apical retrograde cavity, the root segments were randomly divided into 4 groups (n = 25): G1 - Biodentine; G2 - Biodentine + PBS intracanal dressing; G3 - MTA and G4 - MTA + PBS intracanal dressing. All access openings were filled with temporary cement and all root segments were introduced in floral foams moistened with PBS. After 2 months, all root segments were prepared to evaluate the glucose leakage. The amount of glucose leakage was quantified by a spectrophotometer and the data were analyzed using chi-square test (p<0.05).

Results

Traces of the glucose were observed in a higher of samples that received Biodentine apical plug (p<0.05). The exposure to intracanal PBS did not influence the sealing provided by Biodentine and MTA.

Conclusions

The Biodentine had lower sealing ability than MTA. The interaction with PBS intracanal dressing did not improve the sealing ability provided by sealers. Key words:Apexification, dental cements, dental leakage, glucose, pressure.

Micro-CT and nano-CT analysis of filling quality of three different endodontic sealers

OBJECTIVES

To investigate voids in different root canal sealers using micro-CT and nano-CT, and to explore the feasibility of using nano-CT for quantitative analysis of sealer filling quality.

METHODS

30 extracted mandibular central incisors were randomly assigned into three groups according to the applied root canal sealers (Total BC Sealer, Sure Seal Root, AH Plus) by the single cone technique. Subsequently, micro-CT and nano-CT were performed to analyse the incidence rate of voids, void fraction, void volume and their distribution in each sample.

RESULTS

Micro-CT evaluation showed no significant difference among sealers for the incidence rate of voids or void fraction in the whole filling materials (p > 0.05), whereas a significant difference was found between AH Plus and the other two sealers using nano-CT (p < 0.05). All three sealers presented less void volume in the apical third; however, higher void volumes were observed in the apical and coronal thirds in AH Plus using micro-CT (p < 0.05), while nano-CT results displayed higher void volume in AH Plus among all the sealers and regions (p < 0.05).

CONCLUSIONS

Bioactive sealers showed higher root filling rate, lower incidence rate of voids, void fraction and void volume than AH Plus under nano-CT analysis, when round root canals were treated by the single cone technique. The disparate results suggest that the higher resolution of nano-CT have a greater ability of distinguishing internal porosity, and therefore suggesting the potential use of nano-CT in quantitative analysis of filling quality of sealers.

Importance and methodologies of endodontic microleakage studies: A systematic review

INTRODUCTION

It is very important to obtain a tight seal in obturated root canal, making it necessary to conduct clinical or laboratory studies on the sealability of endodontic materials. Different methodologies have been historically used to assess microleakage of different endodontic materials. The aim of the present study was to comprehensively review different material testing methods used in microleakage studies, their interpretation and importance in endodontic literature.

MATERIAL AND METHODS

A systematic search was conducted in Medline, Cochrane, and Web of Science databases. In addition, the reference lists of review articles on the topic were searched. No language restriction was applied. Two independent reviewers screened the article.

RESULTS

Microleakage is considered the single most important risk factor responsible for apical periodontitis. Dye penetration, dye diffusion, bacterial and endototoxin infiltration, fluid filtration, glucose, caffeine and protein infiltration, radioisotope penetration, animal studies, and electrochemical or 3D evaluation are different methodologies used to assess dental leakage. 91 out of 177 articles in the primary search were included in the study. These methods are very divergent in their viewpoints; that is why their results cannot be easily compared. It is necessary to standardize microleakage detection methods in order to more correctly evaluate the phenomena that are found between the root canal wall and the root canal filling materials.

CONCLUSIONS

All the methods are useful if studies are performed strictly with large sample sizes and proper control groups and if the technique can be standardized. Furthermore, more evaluations of the reliability of the methods are strongly recommended. Key words:Dental leakage, review, root canal, material testing methods, data interpretation.

Influence of Sealer and Light-Curing Units on Push-Out Bond Strength Of Composite Resin to Weakened Roots

The aim of this study was to assess the influence of sealer and light-curing unit on regional bond strength of resin composite to the weakened roots. Ninety roots of incisors were experimentally weakened, subjected to biomechanical preparation and filled with either Endofill, AH Plus or MTA Fillapex The roots were desobturated e reinforced with resin composite and fiber post light-activated with one of the light sources: halogen at 600 mW/ cm2 (QTH-600), LED at 800 mW/ cm2 (LED-800) and LED at 1500 mW/ cm2 (LED-1500). The roots were sectioned in slices from cervical, middle and apical root-reinforcement regions and analyzed by push out test, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Bond strength data were analyzed using three-way ANOVA and Tukey´s test (α=0.05). Specimens filled with AH Plus had higher bond strength, followed by MTA Fillapex and Endofill (p<0.05). For light-curing unit, LED-1500 presented superior bond strength than LED-800, which was higher than QTH-600 (p<0.05). The cervical region had the greatest mean values (p<0.05) while apical part showed the lowest bond strength (p<0.05). CLMS revealed remaining filling material in the dentinal tubules for all groups. The eugenol-containing sealer (Endofill) compromised the push-out bond strength of composite resin to the root dentin. Bond strength was favored in the cervical region, and when LED-1500 was used.

Longevity of Bonding of Self-adhesive Resin Cement to Dentin

Objective: To evaluate the effect of root dentin treatment on the bonding of self-adhesive resin cement after 24 hours and after 6 months.

Methods: A total of 48 single-rooted premolars were endodontically treated and divided into four groups (n=12): Adper Scotchbond Multi-Purpose + RelyX ARC (ARC); RelyX U200 (U200); EDTA + RelyX U200 (EU200); and phosphoric acid (H3PO4) + RelyX U200 (HU200). After filling the roots, an Exacto No. 2 fiber post was cleaned, treated with silane (60 seconds), positioned, and light cured (LED; 60 seconds at 1200 mW/cm2). After storage (37°C/24 h), the roots were cut to obtain two discs (1 mm) of each third. They were stored in distilled water (24 hours at 37°C); one disc of each root-third was subjected to the push-out test (0.5 mm/min) at 24 hours and the other disc after six months of water storage (37°C). The data on the root-thirds were averaged for statistical purposes. The average values of bond strength (MPa) were analyzed by two-way analysis of variance and post hoc Student-Newman-Keuls (5%).

Results: There were statistical differences for the treatment of dentin (p&lt;0.001), for time (p=0.003), and the interaction of treatment and time (p=0.017). After 24 hours, we observed lower bond strength in the HU200 group when compared with other groups (ARC, U200, and EU200). After six months, HU200 showed the lowest bond strength. Higher strengths were observed for EU200 and U200 similarly, which were higher than ARC.

Conclusion: The bonding of the self-adhesive resin cement varied over time in the tested groups.

Evaluation of effect of addition of 2% chlorhexidine on the sealing ability of Biodentine: An in vitro study

Aim:

To evaluate the effect of the addition of 2% chlorhexidine on the sealing ability of Biodentine.

Materials and Methods:

Forty-six extracted human premolar teeth with single canal and apical foramen were selected, cleaned, and decoronated to standardize the length of 17 mm. Canals were prepared using ProTaper rotary files till size F4. The samples were divided into 2 experimental groups of 20 samples each on the basis of absence/presence of 2% chlorhexidine in liquid: Group B_M = Biodentine mixed with the provided liquid, Group B_C = Biodentine mixed with 2% chlorhexidine in provided liquid. Three samples, each were assigned to control groups: Group B_P (positive control) = No root end filling was placed, Group B_N (negative control) = Root ends were filled as in Group B_M, and entire external surface was coated with sticky wax. The samples were then evaluated for the apical sealing using fluid filtration method.

Results:

Results were analyzed using Student's t-test (P ≤ 0.05). Group B_C showed the better sealing ability (3.06) as compared to Group B_M (3.85). However, the difference was statistically insignificant (P > 0.05).

Conclusion:

Addition of 2% chlorhexidine to the liquid enhanced the sealing ability of Biodentine.

Applying liquid chromatography-tandem mass spectrometry to assess endodontic sealer microleakage

The objective of this study was to describe a new method for the quantitative analysis of a microleakage of endodontic filling materials. Forty extracted single-rooted teeth were randomly divided into three experimental groups. After root canal shaping, the experimental groups were filled using the lateral condensation technique with the Epiphany system (G1), with gutta-percha + Sealapex (G2), and with gutta-percha + AH Plus (G3). Each root was mounted on a modified leakage testing device, and caffeine solution was used as a tracer (2000 ng mL-1, pH 6.0), applied in the coronal direction towards the tooth apex, creating a hydrostatic pressure of 2.55 kPa. Presence of caffeine in the receiving solution was measured after 10, 30, and 60 days, using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). None of the groups presented microleakage at 10 days. At 30 days, G2 and G3 showed similar infiltration patterns (means: 16.0 and 13.9 ng mL-1, respectively), whereas G1 showed significantly higher values (mean: 105.2 ng mL-1). At 60 days, leakage values were 182.6 ng mL-1 for G1, 139.0 ng mL-1 for G2, and 53.5 ng mL-1 for G3. AH Plus showed the best sealing ability and HPLC-MS/MS showed high sensitivity and specificity for tracer quantification.

Quantitative microleakage analysis of endodontic temporary filling materials using a glucose penetration model

OBJECTIVE

The purpose of this study was to analyze the sealing ability of different temporary endodontic materials over a 6-week period using a glucose penetration model.

MATERIALS AND METHODS

Standardized holes were formed on 48 dentin discs from human premolars. The thicknesses of the specimens were distributed evenly to 2 mm, 3 mm and 4 mm. Prepared dentin specimens were randomly assigned into six groups (n = 7) and the holes in the dentin specimens were filled with two kinds of temporary filling materials as per the manufacturers' instructions as follows: Caviton (GC Corporation, Tokyo, Japan) 2 mm, 3 mm, 4 mm and IRM (Dentsply International Inc., Milford, DE) 2 mm, 3 mm, 4 mm. The remaining specimens were used as positive and negative controls and all specimens underwent thermocycling (1000; 5-55°C). The sealing ability of all samples was evaluated using the leakage model for glucose. The samples were analyzed by a spectrophotometer in quantitative glucose microleakage test over a period of 6 weeks. As a statistical inference, a mixed effect analysis was applied to analyze serial measurements over time.

RESULTS

The Caviton groups showed less glucose penetration in comparison with the IRM groups. The Caviton 4 mm group demonstrated relatively low glucose leakage over the test period. High glucose leakage was detected throughout the test period in all IRM groups. The glucose leakage level increased after 1 week in the Caviton 2 mm group and after 4 weeks in the Caviton 3 mm and 4 mm groups (p < 0.05).

CONCLUSIONS

Caviton had better sealing ability than IRM in the glucose penetration model during 6 weeks. Temporary filling of Caviton to at least 3 mm in thickness is necessary and temporary filling periods should not exceed 4 weeks.

A microleakage study of gutta-percha/AH Plus and Resilon/Real self-etch systems after different irrigation protocols

The development and maintenance of the sealing of the root canal system is the key to the success of root canal treatment. The resin-based adhesive material has the potential to reduce the microleakage of the root canal because of its adhesive properties and penetration into dentinal walls. Moreover, the irrigation protocols may have an influence on the adhesiveness of resin-based sealers to root dentin.

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.

Lack of correlation between obturation limits and apical leakage

The aim of this paper was to evaluate a possible correlation between obturation limits and leakage. Thirty-six extracted human mandibular incisors were used, characterized by straight and single canals, non-anatomical complexities, absence of previous endodontic treatment, complete root formation and patent foramen. For standardization of the specimens for the leakage analysis, foraminal instrumentation was performed up to a Flexofile #25 (Dentsply-Maillefer, Ballaigues, Switzerland). All specimens were instrumented and filled following the same protocol, and the obturation limits were measured using Axiovision 4.5 Software (Carl Zeiss Vision, Hallbergmoos, Germany). The specimens were then separated into three groups (n=12) according to the following variables: Group I--obturation limits ranging from 0 mm to 0.76 mm of the main apical foramen. Group II--obturation limits ranging from 0.77 mm to 0.98 mm of the main apical foramen. Group III--obturation limits ranging from 0.99 mm to 1.68 mm of the main apical foramen. Apical leakage was quantified by fluid filtration. The analyses were confronted using Pearson's test (p>0.05). Groups I, II and III showed Pearson correlation values (r2) of -0.152, -0.186 and 0.058, respectively. No correlation was found between the obturation limits and apical leakage.

Can the Cure Time of Endodontic Sealers Affect Bond Strength to Root Dentin?

The cure time of endodontic sealers may influence the bond strength of fiber posts to root dentin. Forty teeth were selected and endodontically filled using calcium hydroxide cement and then divided into 2 groups according to the time elapsed between endodontic filling and post luting (n = 20): Immediately - glass fiber post luting immediately after endodontic filling; and Delayed - post luting performed 7 days after endodontic filling. The roots were also subdivided according to resin cement used for post luting (RelyX ARC and RelyX Unicem). The specimens were stored at 37°C for 24 h and sectioned in six 1-mm-thick slices from cervical, middle and apical thirds. The slice specimens were submitted to a push-out test at a crosshead speed of 0.5 mm/min, and the bond strength values obtained (MPa) were submitted to two-way ANOVA in a split-plot arrangement and Tukey's test (α=0.05). For both RelyX ARC and Unicem, the bond strength was significantly higher when the posts were cemented 7 days after the endodontic treatment. RelyX Unicem showed significantly higher bond strength values than RelyX ARC for both cementation periods. It was concluded that post luting should be made after the complete setting of the root canal sealer. Self-adhesive resin cement should be preferred for fiber post luting.

Quality of root fillings performed with two root filling techniques. An in vitro study using micro-CT

Objective.

The aim of this study was to compare the presence of voids in root fillings performed in oval and ribbon-shaped canals with two root filling techniques, lateral compaction technique (LCT) or hybrid technique (HT), a combination of a gutta-percha masterpoint and thermoplastic gutta-percha. Furthermore, the obturation time for the two techniques was evaluated.

Materials and methods.

Sixty-seven roots with oval and ribbon-shaped canals were prepared using Profile Ni-Ti rotary files. After preparation, the roots were randomly allocated to two groups according to root filling technique. All roots were filled with AH plus and gutta-percha. Group 1 was filled using LCT (n = 34) and group 2 was filled using HT (n = 33). The obturation time was measured in 30 cases evenly distributed between the two techniques. Voids in relation to the root canal fillings were assessed using cross-section images from Micro-computed Tomography scans.

Results.

All root canal fillings had voids. Permutation test showed no statistically significant difference between the two root filling techniques in relation to presence of voids (p = 0.092). A statistically significant difference in obturation time between the two techniques was found (p < 0.001).

Conclusion.

The present study found no statistically significant difference in percentage of voids between two root filling techniques. A 40% reduction in obturation time was found for the HT compared to the LCT.

In Vitro Effects of External Pressure Changes on the Sealing Ability under Simulated Diving Conditions

Aim. To measure and validate the permeability of pressure changes in correlation to different root filling techniques. Methods. Eighty extracted single-rooted teeth were randomly assigned to one of eight groups of ten teeth. Following standardized instrumentation and irrigation, root canal fillings were performed using either cold lateral condensation, a warm carrier-based gutta-percha obturation technique, a warm carrier-based Resilon, or warm gutta-percha compaction with the downpack/backfill technique. After insertion of a pressure sensor within the pulp chamber ten teeth of each group then underwent simulated dives with pressure measurement and the other ten a dye penetration test during simulated dives to 5.0 bar. Differences were analyzed statistically (P < 0.05) using one-way analysis of variance (ANOVA). Results. When the warm carrier-based gutta-percha obturation technique and vertical gutta-percha obturation techniques were used, there was significant lower intrapulpal pressure to experimental chamber pressure (P > 0.05). When cold lateral condensation or carrier-based Resilon as used, pressure was sometimes almost completely equalized. Conclusions. Warm gutta-percha obturation techniques provide a largely pressure-tight seal whereas the Resilon obturation technique and cold lateral condensation appear to be unsuitable to pressure changes.

Comparative evaluation of sealing properties of different obturation systems placed over apically fractured rotary NiTi files

Aim:

To evaluate sealing properties of different obturation systems placed over apically fractured rotary NiTi files.

Materials and Methods:

Forty freshly extracted human mandibular premolars were prepared by using Protaper (Dentsply-Maillefer, Ballaigues, Switzerland) or the RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) systems (n=20 for each), after which half of the specimens were subjected to instrument separation at the apical level. Roots with and without apically separated instruments (n=5) were filled with the two obturation systems i.e. Thermafil and lateral compaction technique. The modified glucose penetration setup was used to assess the microleakage. The leakage data was statistically analyzed.

Results:

The amount of leakage was significantly lower in specimens containing fractured instruments, regardless of the obturation method used. Roots obturated with Thermafil displayed significantly less leakage than cold lateral compaction technique, both, in the presence and absence of separated instruments. There was no significant difference among specimens prepared with ProTaper and RaCe when Thermafil obturation was done. But with cold lateral compaction technique, RaCe system showed less leakage as compared to ProTaper system.

Conclusion:

The type of obturation may play more important role than the type of instrument or retained/non-retained instrument factor.

The influence of pressure changes on endodontically treated teeth during simulated dives

AIM

  To measure and evaluate pressure changes in the pulp chambers of extracted teeth exposed to hyperbaric conditions during root canal treatment.

METHODOLOGY

  A pressure sensor was inserted and sealed into the pulp chambers of extracted human molars (n = 6). The teeth were subjected to simulated dives to 4.5 bar in a diving chamber. During the simulated ascents and descents, the pressure within the pulp chamber was measured, and the difference between the pressure inside the pulp chamber and the pressure in the diving chamber was calculated. Each tooth underwent two dives with an intact pulp chamber, with a calcium hydroxide dressing, after root canal filling, and after adhesive sealing of the pulp chamber floor with a composite. Differences were analyzed statistically (P < 0.05) using one-way analysis of variance (anova).

RESULTS

  There were no significant pressure differences in teeth with an intact pulp chamber and teeth with a calcium hydroxide dressing. After root filling, however, the increase in pressure inside the pulp chamber was significantly lower (P < 0.05) than that in the diving chamber. After adhesive sealing of the pulp chamber floor with a composite, the pressure inside the pulp chamber was significantly lower (P < 0.05) than the pressure in the diving chamber.

CONCLUSIONS

  In root canal treatment, canal orifices should be sealed with an adhesively bonded composite filling before a dive. The use of a calcium hydroxide dressing after root canal preparation does not disqualify patients from diving.

Is endodontic re-treatment mandatory for every relatively old temporary restoration? A narrative review

OBJECTIVES AND BACKGROUND

In this review, the authors examine whether there is any decisive evidence to support the revision of root fillings that have been exposed to the oral environment for more than three months, undertaken solely because of suspicions of microleakage. Researchers in numerous endodontic studies have addressed the evaluation of coronal microleakage by using different tracers and techniques. The need to achieve a tight, permanent coronal seal as soon as possible after the completion of endodontic treatment is obvious. However, the clinical importance of microleakage studies recently has been questioned because of their wide range and even contradictory results, and findings from only a few clinical investigations have demonstrated a clear relationship between the endodontic success rate and failure rate owed to coronal microleakage in cases involving high-quality endodontic therapy.

METHODS

The authors analyzed commonly cited articles regarding the clinical relevance of microleakage studies and the success rate of teeth with compromised restorations.

CONCLUSIONS

In a review of the literature, the authors found no clear evidence to support immediate replacement of well-obturated endodontic treatment that has lasted more than three months solely because of suspicions of microleakage. It may be prudent in such cases to make a new coronal restoration immediately and to observe the tooth for at least three months before placing the permanent crown.

Identification of root filling interfaces by microscopy and tomography methods

AIM

To assess differences in observed cross-sectional areas of root canals and filling materials, as imaged by three microscopy and two tomography methods.

METHODOLOGY

Six roots filled with laterally compacted Gutta-percha and AH26 were scanned with phase-contrast enhanced microtomography in a synchrotron facility. Reconstructed virtual slices were compared with sections of both wet and acrylic-embedded roots, evaluated also by light and electron microscopy (EM) and laboratory-based microtomography (μCT). The different contrasts of Gutta-percha, voids, sealer and root dentine were identified and correlated. Inner canal border, outer Gutta-percha rim and the external margin of a void were manually delineated, and the enclosed areas were repeatedly measured by three observers. Interobserver and interimaging method differences were tested by 2-way anova with Bonferroni adjustments (P < 0.05). Percentages of Gutta-percha-filled canal areas (PGP) were determined.

RESULTS

Phase-contrast enhanced microtomography revealed internal interfaces and detailed 3D volumes of accentuated voids as well as micrometre-sized particles and gaps within the treated roots. Overestimates in the cross-sectional areas were obtained by light microscopy, whereas underestimates were obtained by μCT and EM. Differences exceeded 40%; however, PGP values by all methods were within 5% for the same slice. Differences between observers were sometimes significant, but they were not method related (<3%).

CONCLUSIONS

Phase-contrast enhanced microtomography is a powerful non-destructive ex vivo investigation method for studying the interfaces within root canals and filling materials at a micrometre resolution. The method does not require damage-prone sectioning/polishing during sample preparation procedures. Caution should be used when quantifying the extent of Gutta-percha in root fillings by measurements using μCT, light and EM.

Interfacial adaptation of the Epiphany self-adhesive sealer to root dentin

OBJECTIVE

The present study was designed to investigate interfacial quality between both Epiphany and Epiphany SE and the surrounding dentin having conventional gutta-percha/AH plus root filling as reference for comparison.

STUDY DESIGN

A sample of 36 human maxillary canines was prepared and assigned to experimental groups of 12 teeth each, designated as G1, Resilon/Epiphany; G2, Resilon/Epiphany SE; and G3, gutta-percha/AH Plus. After the filling procedures, each specimen was horizontally sectioned at 3, 6, and 8 mm from the apex and a metallographic preparation was performed to enable the evaluation under Confocal Laser Scanning Microscopy (CLSM). The integrity of the interface was determined by calculating the ratio between the total sealer/dentin interface and the sealer/dentin interface that presented gap-containing regions. Additionally, the width of each gap was measured and pooled per each specimen for comparison. Statistical analysis was performed using nonparametric methods.

RESULTS

Nonbonding AH Plus/gutta-percha root fillings showed a significantly higher amount of gap-free regions (P < .05). In the same way, nonbonding AH plus root fillings displayed significantly narrower gaps compared with the 2 adhesive root-filling groups (P < .05).

CONCLUSIONS

Under the present in vitro conditions, the quality of the interfacial adaptation of the current adhesive root fillings is compromised even when teeth with simple anatomic features were obturated under well-monitored laboratory conditions.

Correlation between sealer penetration and microleakage following the use of MTAD as a final irrigant

The relationship between sealer penetration and apical microleakage following the use of MTAD as an irrigant in root canal procedures was evaluated. A collection of 120 human teeth was divided into three groups of 40 in each group. The final rinse was varied as follows: group 1 - the final rinse was saline solution, group 2 - ethylene diamine tetraacetic acid and for group 3 - MTAD. Each group was then divided into two subgroups (20 teeth) and filled with gutta percha and either AH Plus or Dorifill sealer. Half of the teeth were selected for dye penetration testing and the sealer penetration in the remaining teeth was evaluated using scanning electron microscope. There were no significant differences between the three irrigants, but there was less dye penetration in teeth sealed with AH Plus than Dorifill. Penetration of the sealer was better in the MTAD and ethylene diamine tetraacetic acid groups than in the saline group. Statistically, there was no significant difference between the sealer penetration into the dentinal tubules and the dye penetration.

[Microleakage of root canal fillings with GuttaFlow and Resilon compared with lateral condensation]

Epiphany/Resilon and GuttaFlow are newly developed methods for obturation of the root canal system. Epiphany/Resilon is a thermoplastic, synthetic polymer-based root canal filling material which enables the bonding to the dentin root canal wall during root canal obturation. GuttaFlow is a cold flowable filling system for the obturation of root canals, combining sealer and gutta-percha in one product. The purpose of this study was to assess the leakage of the Epiphany/Resilon or GuttaFlow root canal filling compared with lateral condensation of gutta-percha. For this study were used 45 human extracted teeth, chemo mechanically prepared, divided into three groups and obturated with gutta-percha/AH Plus, Epiphany/Resilon and GuttaFlow. For dye penetration all teeth were centrifuged for three minutes at 30 g in 2% methylene blue and dissolved in 65% nitric acid for 3 days. The extracted methylene blue was determined with Photometer. Root Canal fillings with Epiphany/Resilon showed less dye penetration than lateral condensation of gutta-percha and GuttaFlow. Epiphany/Resilon is ideally suited as a root canal filling material.

Comparative analysis of leakage in root canal fillings performed with gutta-percha and Resilon cones with AH Plus and Epiphany sealers

OBJECTIVE

The aim of this study was to compare the leakage of root canal fillings of gutta-percha or Resilon cones in association with AH Plus or Epiphany sealer.

STUDY DESIGN

Four groups of premolars (n = 64) were instrumented to size 45/.04 ProFile and filled with laterally compacted gutta-percha cones or Resilon cones in association with AH Plus or Epiphany sealer. The specimens were stored for 2 weeks at 37 degrees C and 100% humidity. After that, leakage was measured using the fluid filtration method and determined as microL/min.10 psi.

RESULTS

Homogeneity of variance and multiple comparisons tests were performed and indicated that root fillings with the combination of gutta-percha cones and AH Plus sealer showed lower leakage values (P < .05) than the other groups.

CONCLUSION

Considering the experimental conditions and the results obtained, it was concluded that fillings made with gutta-percha cones in combination with AH Plus sealer had the best performance.

Microleakage of various root filling systems by glucose filtration analysis

OBJECTIVE

The aim of this study was to evaluate the microleakage of Resilon + Epiphany, EndoRez, Activ GP, and conventional AH Plus + gutta-percha technique using the glucose filtration model.

STUDY DESIGN

One hundred twenty maxillary incisors were divided into 5 experimental and 2 control groups. After root canal shaping, the experimental groups were filled with AH Plus + gutta-percha (lateral compaction), Resilon + Epiphany (lateral compaction), AH Plus + Protaper's proprietory cone, EndoRez + sealer, or Activ GP + sealer). The specimens were mounted on a glucose model and samples were taken for 3 weeks for leakage measurement.

RESULTS

No statistically significant difference was observed between the leakage of all groups at the 3 testing periods (P > .05).

CONCLUSION

The filling materials with the monoblock concept do not seem to be superior to the conventional AH Plus + gutta-percha system regarding microleakage.