Coronal leakage of two root canal sealers containing calcium hydroxide after exposure to human saliva

Antifungal and genotoxic effects of Thymus serpyllum as a root canal irrigant

OBJECTIVES

The aim of this study was the assessment of the efficiency of the ethyl acetate (EthOAc) extract of Thymus serpyllum against Candida albicans and to compare it with sodium hypochlorite (NaOCl) and chlorhexidine (CHX), as well as their genotoxic effect.

MATERIAL AND METHODS

The antifungal effectiveness of the EthOAc extract of Thymus serpyllum was determined using the agar disk diffusion method. The inhibition zones induced by the EthOAc extract were compared after 5 min, 60 min, and 24 h to those induced by standard solutions (2% CHX and 2% NaOCl). An in vitro genotoxicity assay was performed in cultured lymphocytes from the blood of human volunteers to observe micronuclei formation. Statistical analysis of the results was performed using the Kruskal-Wallis test and one-way analysis of variance.

RESULTS

The inhibition zone of combination of CHX with EthOAc extract of Thymus serpyllum against C. albicans was 29.7 mm after 5 min, 28.3 mm after 60 min, and 29 mm after 24 h. The inhibition zone of NaOCl in combination with EthOAc extract of Thymus serpyllum against C. albicans was 0 mm. The EthOAc extract of Thymus serpyllum did not show a genotoxic effect on lymphocyte cells.

CONCLUSIONS

The EthOAc extract of Thymus serpyllum in combination with CHX may be a useful root canal disinfection in endodontic therapy.

Synthesis and characterization of calcium-releasing elastomeric resin-based endodontic sealers

OBJECTIVES

To evaluate the incorporation of halloysite nanotubes (HNTs) loaded with one of two calcium sources (i.e., calcium hydroxide/CaOH2 or beta-tricalcium phosphate/β-TCP) on the physicochemical and biological properties of an experimental resin-based dual-cured endodontic sealer.

MATERIALS AND METHODS

HNTs were encapsulated with CaOH2 or β-TCP at 10 wt.%. HNTs containing CaOH2 or β-TCP were added into the experimental sealers at 50 wt.%. The control sealers were the calcium-free HNT-modified resin-based experimental sealer and AH Plus™, a commercially available endodontic sealer. Degree of conversion, setting time, flow, film thickness, radiopacity, dimensional stability, and calcium ions release were determined. Antibiofilm properties and cytocompatibility of the formulated sealers and commercial control were also evaluated. One and two-way ANOVA analysis followed by Tukey's post hoc test was conducted to evaluate the effect of the independent variable on the evaluated properties.

RESULTS

FTIR confirmed the encapsulation of calcium sources into HNTs. Regarding flow and film thickness, the values obtained from these sealers were in accordance with the specifications provided by ISO 6876. For radiopacity, AH Plus™ achieved the highest radiopacity (p<0.05). Among the experimental formulations, all experimental HNT-containing compositions exhibited values below 3 mm Al. The experimental sealers showed greater dimensional changes when compared to the commercial (AH Plus™) control. The release of calcium ions was observed for the HNT_CaOH2 and HNT_β-TCP sealers without statistical differences. Experimental sealers containing HNT_CaOH2 and HNT_β-TCP significantly reduced the CFU/mL count and showed cell compatibility.

CONCLUSIONS

The findings of this study demonstrate that the incorporation of HNT_CaOH2 or HNT_β-TCP into resin-based experimental sealers promoted antimicrobial effects and gradual calcium release without impairing cytocompatibility or physicochemical properties of the sealers. Still, an adjustment to reach the minimal radiopacity established by ISO 6876 is needed.

CLINICAL RELEVANCE

The experimental resin-based sealers seemed to be an alternative for endodontics. The incorporation of calcium sources exerts promising antimicrobial effects while displaying low cell toxicity.

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.

Nitinol Type Alloys General Characteristics and Applications in Endodontics

A very extensive literature review presents the possibilities and needs of using, in endodontics, the alloys commonly known as nitinol. Nitinol, as the most modern group of engineering materials used to develop root canals, is equilibrium nickel and titanium alloys in terms of the elements’ atomic concentration, or very similar. The main audience of this paper is engineers, tool designers and manufacturers, PhD students, and students of materials and manufacturing engineering but this article can also certainly be used by dentists. The paper aims to present a full material science characterization of the structure and properties of nitinol alloys and to discuss all structural phenomena that determine the performance properties of these alloys, including those applied to manufacture the endodontic tools. The paper presents the selection of these alloys’ chemical composition and processing conditions and their importance in the endodontic treatment of teeth. The results of laboratory studies on the analysis of changes during the sterilization of endodontic instruments made of nitinol alloys are also included. The summary of all the literature analyses is an SWOT analysis of strengths, weaknesses, opportunities, and threats, and is a forecast of the development strategy of this material in a specific application such as endodontics.

Bacterial leakage assessment in root canals sealed with AH Plus sealer modified with silver nanoparticles

BACKGROUND

Successful endodontic therapy requires prevention of bacterial leakage between the root canal filing and root-canal walls. Sealing quality of a root canal filling depends strongly on the sealing ability of the sealer used. The present study aimed to evaluate the bacterial leakage resistance of AH Plus sealer modified with silver nanoparticles.

METHODS

Forty sound teeth were obturated using lateral compaction technique except for five teeth as the negative controls. After considering five teeth as the positive controls (filled without sealer), the remaining teeth were assigned to two groups (n = 15) in terms of the sealer used (AH Plus sealer and silver nanoparticle-modified AH Plus). Bacterial leakage was evaluated in saliva using the two-chamber technique in every 24 h. When all the samples in the test groups were contaminated, the study was terminated. The data were analyzed with log-rank statistical test.

RESULTS

All samples in both experimental groups were contaminated during the 3-months period of observation. There was no significant difference in contamination time between study groups (P > 0.05).

CONCLUSIONS

Silver nanoparticles used in tested concentration did not improve the bacterial leakage resistance of AH Plus sealer.

Comparison of the penetration depth of five root canal sealers: A confocal laser scanning microscopic study

Background:

Sealer penetration into dentinal tubules eliminates the pathways for bacterial leakage and entombs intratubular bacteria.

Aim:

The aim of this study was to evaluate and compare the depth of radicular dentinal tubule penetration of five root canal sealers using confocal laser scanning microscopy.

Methods:

Fifty freshly extracted single-rooted maxillary anterior teeth were used. After decoronation at the cementoenamel junction, they were prepared to ProTaper size F3. After irrigation with 5 mL smear clear, 5 mL 5% sodium hypochlorite and 5 mL distilled water alternatively, the samples were randomly divided into five groups (n = 10) and obturated by lateral compaction technique using the test sealers labeled by fluorescent rhodamine B dye (Mayor Diagnostics, Mumbai, India). Zinc oxide eugenol (ZOE) (Prime Dental Products), EndoREZ (Ultradent), Sealapex (SybronEndo), AH Plus (Dentsply Maillefer), and MTA-Fillapex (Angelus) formed the test groups. Teeth were then positioned in blocks of orthodontic resin. Three horizontal sections of 1-mm representing coronal middle and apical thirds were made and examined with Zeiss (laser scanning microscope [LSM] 780) confocal LSM. Images were analyzed using ZEN 2.1 software.

Statistical Analysis:

Data were recorded and subjected to statistical analysis using one-way ANOVA test.

Results:

Maximum penetration depth was demonstrated by AH Plus in the coronal and apical thirds, MTA-Fillapex in the middle thirds, while minimum penetration depth was seen in ZOE in the coronal and middle thirds and Sealapex in the apical thirds. None of the root canal sealers were able to penetrate the complete depth of radicular dentinal tubules.

Conclusion:

While AH Plus and MTA-Fillapex showed the highest penetration into radicular dentinal tubules, ZOE and Sealapex demonstrated the least penetration.

Development Strategy of Endodontic Filling Materials Based on Engineering and Medical Approaches

This article is a literature review aimed at presenting the general state of knowledge in manufacturing engineering and materials engineering to develop engineering materials applied for endodontic treatment as filling materials. Particular attention was paid to theoretical analyses concerning the selection of methods for developing and obturating root canals and discussing the results of experimental studies available in the literature. These activities aimed to compare the importance of the most commonly used endodontic filling materials based on gutta-percha or polymeric polyester materials, commonly known as resilon, respectively. The motivation to take up this complex, multi-faceted topic in this paper is the extent of caries, periodontal disease, and other oral diseases in 3 to 5 billion people, often affecting toothlessness and contributing to an increase in the index of disability-adjusted life years (number). Endodontics is an important element of the authors’ concept of Dentistry Sustainable Development (DSD) > 2020. The principles of qualifying patients for endodontic treatment are discussed. The introduction of rotary tools, especially manufactured from Nitinol alloy, to develop root canals and the latest thermohydraulic and condensation techniques for obturation guarantee progress in endodontics. The “Digital Twins” methodology was used, rooted in the idea of Industry 4.0 and the resulting idea of Dentistry 4.0, as well as knowledge management methods, to perform experimental research in virtual space, concerning methods of developing and obturating the root canal and assessing the tightness of fillings. Microscopic visualization methods were also used. Significant factors determining the effectiveness of endodontic obturation are the selection of the filling material and the appropriate obturation method. The generalized dendrological matrix of endodontic filling materials considers the criteria of mechanical strength influencing the potential root fracture and the quality of root canal filling. The results of the SWOT point analysis (strengths and weaknesses, opportunities, threats) were also compared. For both filling materials, the weaknesses are much less than the strengths, while the threats are slightly less than the opportunities for the gutta-percha-based material, while for resilon the opportunities are much smaller than the threats. It requires the application of an appropriate development strategy, i.e., MAXI-MAXI in the case of a filling material based on gutta-percha and MAXI-MINI in the case of resilon. Therefore, the analysis of these experimental data does not indicate the real competitiveness of resilon for the gutta-percha-based material. This material deservedly maintains its strong position as the “Gold Standard of Endodontics”.

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.

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.

Comparison of bacterial microleakage of three bioactive endodontic sealers in simulated underwater diving and aviation conditions

BACKGROUND

Bacterial microleakage is an important cause of apical periodontitis and endodontic treatment failure. This study aimed to assess the bacterial microleakage of nano-mineral trioxide aggregate (nano-MTA) as a sealer, Endoseal MTA, and GuttaFlow Bioseal sealers in atmospheric pressure, and simulated underwater diving and aviation conditions.

METHODS

In this in vitro, experimental study, 180 extracted single-rooted teeth were cleaned and shaped, and were then randomly divided into three groups for single-cone obturation using Endoseal MTA, GuttaFlow Bioseal, or nano-MTA as a sealer. Each group was then randomly divided into three subgroups, and subjected to ambient atmospheric pressure, 2 atm pressure (to simulate underwater diving), and 0.5 atm pressure (to simulate aviation) using a custom-made pressure chamber. The teeth then underwent microbial leakage test using Streptococcus mutans (S. mutans), and the percentage of samples showing microleakage was recorded for up to 1 month, and analyzed using the Chi-square test.

RESULTS

The three sealer groups were significantly different regarding bacterial microleakage (P < 0.05). The nano-MTA group showed significantly higher microleakage after 15 days than the other two groups (P = 0.006). The effect of pressure on bacterial microleakage was not significant in any sealer group (P > 0.05).

CONCLUSION

Within the limitations of this in vitro study, it may be concluded that single-cone obturation technique using nano-MTA as a sealer results in lower resistance to bacterial microleakage compared with the use of GuttaFlow Bioseal, and Endoseal MTA. Pressure changes in simulated underwater diving and aviation conditions had no significant effect on bacterial microleakage. Trial Registration Number This is not a human subject research.

Radiographic and antimicrobial evaluation of enterococcus Faecalis and Actinomyces Israelii micro-organisms after photodynamic therapy (aPDT)

This study evaluated the action of Antimicrobial Photodynamic Therapy (aPDT) on Enterococcus faecalis and Actinomyces israelii. Samples were taken from the root canal system, at different stages of treatment and bacteria were identified through qPCR. Fifty teeth (incisors, canines, and premolars) with pulp necrosis and periapical lesion diagnosis were randomly selected and divided into 2 groups: Group 1 (G1) - Endodontic Therapy with Mechanical Chemical Preparation (MPQ) and intracanal medication; Group 2 (G2) - Endodontic therapy with MPQ, intracanal medication, and 2 applications of aPDT. APDT was performed with application of 0.005% methylene blue, wavelength of 660 nm, and 90 seconds. Follow-up was performed with an initial x-ray and an x-ray 60 days after the end of treatment. The radiographs were scored evaluated by two examiners to classify periapical repair: total repair, partial repair, doubtful repair, or no repair. Enterococcus faecalis was found more frequently in G1 than G2. Actinomyces israelii was found equally in G1 and G2. Evaluation of the two bacteria between collections 1, 2 and 3, showed that there was no difference, both in G1 and in G2. There was association between the variables group and repair classification in radiographs evaluation. APDT did not promote better results in endodontic treatment, being similar to conventional treatment. However, this study pointed out that molecular methods may not be efficient in detecting bacteria after treatment, and colony-forming units may complement, being an effective quantifying method. Therefore, new studies must be carried out to show the possible effectiveness of aPDT.

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.

Clinical and radiographic outcome of the root canal treatment of infected teeth with associated sinus tract: A retrospective study

This retrospective study evaluated the outcome of the endodontic treatment/retreatment of teeth with intraoral sinus tracts. Seventy-two teeth from 70 individuals were included. One operator treated all teeth over about 20 years. Time for the sinus tract to heal was recorded. Treatment outcome was evaluated after at least 1 year and classified as healed, healing or diseased. The overall healed rate of periradicular lesions was 73.6% (74.1% for treatment and 72.2% for retreatment). In 6 (8.3%) teeth, lesions were healing. Thirteen teeth (18.1%) exhibited persistent disease. In 68/72 (94.4%) cases, the sinus tract healed in less than 1 month. No preoperative/intraoperative variable affected the outcome (P > 0.05). Missing restorations had a negative impact (P < 0.05). Healing of both the sinus tract quickly after treatment and the periradicular lesion later were usually achieved. Closure of the sinus tract in the first month was a good predictor of lesion healing.

A Novel Polyurethane Expandable Root Canal Sealer

INTRODUCTION

Endodontic sealers play a vital role in the obturation of root canal space. The aim of this study was to evaluate the utility of a recently developed polyurethane expandable sealer (PES), along with its cytotoxicity and dimensional changes.

METHODS

L929 fibroblasts and an cell viability assay (MTS assay) were used to determine the cytotoxicity of dental sealers (AH Plus [Dentsply Maillefer, Ballaigues, Switzerland], Sure-Seal Root [Sure Dent Corporation, Gyeonggi-do, South Korea], and the PES) at 24, 48, 72, and 96 hours. An advanced choroidal neovascularization model was used to assess the effect of these sealers on angiogenesis. Thirty-six extracted single-rooted human teeth were prepared and randomly divided into 3 groups (n = 12). Obturation was performed with gutta-percha and a sealer using lateral compaction as follows: group 1, AH Plus; group 2, Sure-Seal; and group 3, PES. The average depth of sealer penetration into dentinal tubules was measured with a scanning electron microscope. Data were analyzed using 1-way analysis of variance and post hoc Tukey tests (level of significance, P < .05).

RESULTS

The values of MTS, choroidal neovascularization, and the penetration depth of PES were significantly higher than in other experimental groups (P < .05). The lowest values were noted in specimens of AH Plus, whereas the highest were detected in the PES group.

CONCLUSIONS

PES showed promising results in terms of biocompatibility and dentinal tubule adaptation and penetration.

Comparative Evaluation of Fracture Resistance of Endodontically Treated Teeth Restored with Different Core Build-up Materials: An In Vitro Study

The aim is to evaluate the fracture resistance of endodontically treated teeth restored with posterior direct composite (PRC) resin, bulk-fill composite resin, dual-cure composite (DCC) resin, and short fiber-reinforced composite (SFC) resin material.

Sealing Ability of Alkaline Endodontic Cements versus Resin Cements

Penetration of oral bacteria through root fillings leads to their long term failure. Dimensionally stable alkaline cements have been developed. A saliva challenge model was used to compare resistance to bacterial penetration of these alkaline cements to conventional root fillings that combine gutta percha (GP) with epoxy resin sealers. A sample of 140 human roots with single straight canals prepared to standard length and canal size were obturated with mineral trioxide aggregate (MTA) (Nex MTA or MTAmix), with an alkaline calcium hydroxide hard setting cement (Supercal), or with GP and a resin cement (either AH-Plus or Zirmix). Negative control roots were sealed with wax, while positive controls were left open. The test assemblies were gamma sterilised, then the coronal root face was exposed daily to fresh stimulated human saliva diluted in broth. Bacterial penetration was determined by assessing growth in sterile brain-heart infusion (BHI) medium in contact with the root apex. Using Kaplan–Meier survival analysis, in order of performance from highest to lowest: Negative control, Supercal, Nex MTA, Zirmix, MTAmix, GP + AH-Plus, and the positive control. In addition, statistically significant differences were noted between Supercal and AH-Plus, and between the two MTA cements. It can be concluded that alkaline cements, particularly Supercal, can show considerable resistance to bacterial penetration from constant saliva challenge, and provide superior sealing ability in comparison to resin cements. While this property is due mostly to dimensional stability, the release of hydroxide ions could be a contributing factor to impaired bacterial survival, and this aspect should be explored further.

Significant variation in salivation by short-term suggestive intervention: a randomized controlled cross-over clinical study

INTRODUCTION

Most dental procedures require a dry working environment. Although many evaporative drying methods are available, an additional reduction of salivary flow would often be helpful.

METHODS

This prospective randomized cross-over study compares salivary production in 31 volunteers during direct, indirect, and non-suggestive (control group) intervention. Overall, each volunteer underwent four salivation measurements, i.e. two measurements during two different types of hypnotic suggestion (indirect and direct) arranged in random order and two control sections. All four measurements were conducted successively.

RESULTS

Both suggestive methods significantly reduced salivary production in comparison to the two control sections (direct suggestion Δ = 1.46 grams per 5 min, p < 0.001, indirect suggestion Δ = 0.94 grams per 5 min, p = 0.039). Direct suggestion showed a significantly higher reduction of salivary production than indirect suggestion (Δ = -0.53 grams per 5 min, p = 0.001).

CONCLUSIONS

Hypnotic suggestion represents a simple and inexpensive method to reduce salivation and could thus create a better working environment for more comfortable dental treatments for both patients and dentists.

Ex vivo microbial leakage after using different final irrigation regimens with chlorhexidine

Objective:

To assess the influence of final irrigation protocols with chlorhexidine in the coronal leakage of Enterococcus faecalis in filled root canals.

Material and Methods:

Seventy single-root canals from extracted teeth were prepared using ProTaper instruments. The irrigation protocol accomplished an alternating irrigation with 5 mL of 2.5% sodium hypochlorite (NaOCl) and 17% EDTA between each file. The teeth were randomly divided into four experimental groups (n=15) according to the final irrigation regimen: group 1, without final irrigation; group 2, irrigation with 10 mL 2.0% chlorhexidine (CHX); group 3, with a final application of EC40^TM; and group 4, irrigation with the combination (1:1) of 0.2% CHX + 0.1% cetrimide (CTR). All the teeth were mounted in a two-chamber apparatus and the coronal access was exposed to E. faecalis. The presence of turbidity in the BHI broth over a period of 180 days was observed. The Friedman test was used for statistical analysis.

Results:

EC40^TM varnish showed the least leakage at 180 days, and was statistically similar to 2% CHX. No significant differences were observed between the group without final irrigation and the 2% CHX group or 0.2% CHX + 0.1% CTR.

Conclusions:

In this ex vivo study, EC40^TM showed the longest delayed coronal leakage of E. faecalis, although without significant differences from 2% CHX.

Properties and applications of calcium hydroxide in endodontics and dental traumatology

Calcium hydroxide has been included within several materials and antimicrobial formulations that are used in a number of treatment modalities in endodontics. These include, inter-appointment intracanal medicaments, pulp-capping agents and root canal sealers. Calcium hydroxide formulations are also used during treatment of root perforations, root fractures and root resorption and have a role in dental traumatology, for example, following tooth avulsion and luxation injuries. The purpose of this paper is to review the properties and clinical applications of calcium hydroxide in endodontics and dental traumatology including its antibacterial activity, antifungal activity, effect on bacterial biofilms, the synergism between calcium hydroxide and other agents, its effects on the properties of dentine, the diffusion of hydroxyl ions through dentine and its toxicity. Pure calcium hydroxide paste has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. Its main actions are achieved through the ionic dissociation of Ca(2+) and OH(-) ions and their effect on vital tissues, the induction of hard-tissue deposition and the antibacterial properties. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. It has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also an effective anti-endotoxin agent. However, its effect on microbial biofilms is controversial.

A comparative evaluation of the sealing ability of 2 root-end filling materials: an in vitro leakage study using Enterococcus faecalis

OBJECTIVE

The purpose of this study was to evaluate the sealing ability of EndoSequence Bioceramic Root-end Repair (BCRR) material when compared with white mineral trioxide aggregate (WMTA).

STUDY DESIGN

Forty single-rooted teeth were instrumented, obturated with gutta-percha, root-end resected, and retrofilled with 2 different materials: white ProRoot MTA (WMTA) (n = 15) and BCRR (n = 15). Unfilled specimens (n = 10) received no retrofill and were used as controls. All groups received E. faecalis in a created reservoir coronal to the root filling and the presence of microleakage was evaluated by counting the colony-forming units from each specimen. The results were analyzed with 1-way analysis of variance.

RESULTS

There was no significant difference in leakage between the 2 experimental groups, but there was a significant difference with the control (P ≤ .05).

CONCLUSIONS

This study suggests that BCRR is equivalent in sealing ability to WMTA when used as root-end filling material in vitro.

Bacterial leakage in root canals filled with conventional and MTA-based sealers

AIM

To evaluate bacterial leakage after filling root canals with several endodontic sealers, including MTA-based materials.

METHODOLOGY

One hundred and thirty single-rooted extracted human teeth were randomly divided into experimental groups (n = 15) and two control groups (n = 5). Six root canal sealers were namely: AH Plus (AHP), Sealer 26 (S26), Epiphany SE (ESE), Sealapex (SEL), Active GP (AGP), Endofill (EDF), and two MTA-based sealers were namely: Endo CPM Sealer (CPM) and MTA-based sealer (MTAS, MTA Sealer). Teeth in the control groups were either filled with no sealer or made completely impermeable. Root canals were prepared and filled with either gutta-percha and one of the sealers or with Resilon and Epiphany SE. Teeth were sterilized by ethylene oxide prior to the bacterial leakage experiments using Enterococcus faecalis. Leakage was evaluated every 24 h for 16 weeks. Data were analysed by the Kaplan-Meier, Kruskal-Wallis and Dunn tests at 5% significance.

RESULTS

Control groups had either immediate leakage or no leakage. During 120 days, significantly more leaking samples were detected for AGP, CPM and MTAS (P < 0.05). The best sealing ability was observed for AH Plus and Sealapex (P < 0.05).

CONCLUSIONS

All sealers evaluated allowed bacterial leakage. The MTA-based sealers had the most leakage.

Potential systematic error in laboratory experiments on microbial leakage through filled root canals: review of published articles

AIM

To systematically evaluate whether published studies on microbial leakage through filled root canals in human teeth embedded in a two-chamber system were properly controlled. Specifically, the control for the assumption that leakage should occur through the root canal rather than other routes was investigated.

METHODOLOGY

A systematic search was conducted using Medline, Biosis, Cochrane, Embase, and Web of Science databases. In addition, the reference lists of review articles pertaining to the topic were searched. No language restriction was applied. Two independent reviewers screened titles and abstracts. All articles deemed appropriate by either reviewer were included in the full-text evaluation. In case of disagreement, a referee arbitrated between the reviewers.

RESULTS

With 93.8% agreement prior to discussion and arbitration, 67 articles were included. On average, the size of the negative control group was 30% (mean) of the n in the experimental groups (minimum=0.0%, maximum=100%, SD=27%). The majority of studies (57 of 67) used inadequate negative controls. The whole root was covered with the sealing material in these specimens, whilst the root tip was left uncovered in the experimental groups. Consequently, leakage between outer root surface and sealing material was not controlled for. The authors of the remaining 10 communications did not state clearly how negative control assessments were performed.

CONCLUSIONS

Experimental investigations should be performed to assess the routes of microbial leakage in two-chamber models.

Volumetric analysis of root fillings using spiral computed tomography: an in vitro study

AIM

To analyse volumetrically using spiral computed tomography (SCT) the efficacy of various techniques to fill root canals.

METHODOLOGY

Root canals in 40 maxillary central incisors were instrumented with K-files to size 60 and the volume of the canal measured using SCT. The teeth were divided into four groups of 10 each and root filled by lateral compaction, Thermafil, Obtura II and System B techniques, respectively. AH plus was used as sealer with all techniques. The filled volume in each canal was measured using SCT and the percentage of obturated volume (POV) was calculated. The data were statistically analysed using Kruskal-Wallis test and Mann-Whitney U-test.

RESULTS

The four groups were comparable in canal volume. The overall POV was 80.4%, 93.3%, 84.8% and 93.7% for lateral compaction, Thermafil, Obtura II and System B, respectively (P < 0.05).

CONCLUSION

The greatest POV was obtained with System B and Thermafil. Voids were seen in all root fillings.

In vivo evaluation of the sealing ability of two endodontic sealers in root canals exposed to the oral environment for 45 and 90 days

This in vivo study evaluated the sealing ability of a resin-based sealer (AH Plus) and a zinc oxide-eugenol sealer (Endofill) in dogs' teeth, exposed to the oral environment for 45 and 90 days. Forty eight lower incisors from 8 dogs were endodonticaly treated. A stratified randomization determined the sealer use in each root canal. All canals were filled using the lateral condensation technique. The excess filling material at the cervical portion of the root canal was sectioned, leaving a 10-mm obturation length inside the canal. Teeth were provisionally sealed with glass ionomer cement for 24 h and the canals were exposed to the oral environment for either 45 or 90 days. Therefore, the experimental groups were as follows: A45- AH Plus for 45 days; A90- AH Plus for 90 days; E45- Endofill for 45 days; and E90- Endofill for 90 days (n=12). After the experimental period, the dogs were killed and the lower jaw was removed. The incisors were extracted and the roots were covered with two coats of nail varnish. The teeth were immersed in India ink for 96 h and submitted to diaphanization. Dye leakage (in mm) was measured using stereomicroscopy (10x magnification). The results were statistically analyzed using two-way ANOVA and Tukey test for multiple comparisons (á = 0.05). Group E90 (2.03+/-0.94) showed significantly higher mean leakage value than all other groups (p<0.001). None of the sealers, in both study conditions, were able to prevent dye leakage.

Prevalence of apical periodontitis in root canal-treated teeth from an urban French population: influence of the quality of root canal fillings and coronal restorations

This cross-sectional study determined the prevalence of apical periodontitis in 1035 root canal-treated teeth from adult French patients and investigated the influence of the quality of canal fillings and coronal restorations on the periradicular status. Periapical radiographs were used for analyses, and teeth were classified as healthy or diseased according to the periapical index scoring system. Overall, the prevalence of apical periodontitis in root canal-treated teeth was 33%. Only 19% of the teeth had endodontic treatments rated as adequate. The success rate (number of healthy teeth) for cases with adequate endodontic treatment was 91%, which was significantly higher when compared with teeth with inadequate treatment (61%). Teeth with adequate restorations had significantly decreased prevalence of apical periodontitis (29%) as compared with teeth with inadequate restorations (41%). The combination of adequate endodontic treatment and adequate restorations yielded the highest success rate (93.5%). The quality of the endodontic treatment was the most important factor for success, although the quality of the coronal restoration also influenced the treatment outcome.

Bacterial leakage in root canals filled with calcium hydroxide paste associated with different vehicles

This in vitro study evaluated, using a bacterial leakage model, whether intracanal medication with calcium hydroxide [Ca(OH)2]-based pastes prepared with different vehicles, has inhibitory effect on corono-apical leakage of bacteria. Forty instrumented human canines were dressed with Ca(OH)2 p.a. associated with: G1 = distilled water; G2 = polyethylene glycol (PG); G3 = PG + CMCP; and G4 = glycerin. Five teeth with intact crowns served as negative controls and 5 instrumented teeth without temporary dressing served as positive controls. All teeth were mounted in a 2-chamber apparatus and then exposed to human saliva for 63 days. Leakage was recorded when turbidity was observed in the lower chamber. Fifty percent of the samples of G1 and G2, 10% of G3 and 80% of G4 were fully contaminated after 9 weeks. Statistically significant differences were observed with paired comparisons G3 and G4 (p=0.0069), with G3 achieving better seal against bacterial leakage than G4.

The effect of the canal-filled area on the bacterial leakage of oval-shaped canals

AIM

To compare the sealing ability and the canal-filled area (gutta-percha + sealer) of three current filling techniques in oval-shaped canals.

METHODOLOGY

A total of 50 oval-shaped root canals were prepared and root filled as follows: G1: lateral condensation (n = 10), G2: System B (n = 10) and G3: Thermafil system (n = 10). All teeth were mounted in a two-chamber apparatus and the coronal access was exposed to human saliva. The appearance of turbidity in the BHI broth over a 15-week period was observed. A cross section of each tooth was made 5 mm from the apex and the samples were prepared for microscopic analysis. Digital image measurements of the cross-sectional area and the area filled by gutta-percha and sealer were performed. Log-rank and Fisher's exact tests were used to analyse the leakage data. Student's t-test was used to analyse the filled-area data.

RESULTS

Overall, 30% of the specimens of G1 and G2 and 20% of G3 demonstrated leakage after 15 weeks and no significant difference was found amongst the groups (P > 0.05). The percentage of canal-filled area was 68, 70 and 78%, respectively (P > 0.05). The correlation analysis revealed no significant relation between the pattern of bacterial leakage and canal-filled area (P = 0.128).

CONCLUSIONS

No significant difference in apical sealing and canal-filled area in oval-shaped canals was seen between the three filling techniques. No significant correlation was found between the quality of the apical seal and the filled-area of the root canal space.

The sealing ability of GuttaFlow in oval-shaped canals: an ex vivo study using a polymicrobial leakage model

AIM

To compare systematically the sealing ability provided by four endodontic cements: AH Plus, Pulp Canal Sealer EWT, RoekoSeal and GuttaFlow.

METHODOLOGY

A sample of 100 human mandibular incisors with oval-shaped canals was selected from an initial sampling of two hundred teeth. The root canals in 80 teeth were prepared and filled by the same operator using the cold lateral compaction technique with one of the following four cements (n = 20): G1: AH Plus; G2: Pulp Canal Sealer EWT; G3: RoekoSeal and G4: GuttaFlow. Ten teeth with intact crowns served as negative controls and 10 teeth that were not root filled served as positive controls. All teeth were mounted in a two chamber apparatus and then exposed to human saliva. The number of days over a 9-weeks-period was recorded for the appearance of turbidity in the BHI broth. A Log-rank test was used to analyse the leakage data.

RESULTS

Overall, 30% of the samples of the AH Plus group (G1) and 35% of the Pulp Canal Sealer EWT group (G2) were fully contaminated after 9 weeks, whereas 15% of RoekoSeal (G3) and GuttaFlow (G4) groups were fully contaminated. There was a significant difference between (G1/G2) and (G3/G4) (P < 0.05). There was no significant difference between G1 and G2 or between G3 and G4 (P > 0.05).

CONCLUSION

The silicone-based sealers revealed the best results throughout the experimental period. Leakage patterns of AH plus and Pulp Canal Sealer were statistically similar.

Polymicrobial Leakage of Four Root Canal Sealers at Two Different Thicknesses

The present study investigated the sealing ability of four root canal sealers at two different thicknesses. There were 82 maxillary incisors roots prepared with Gates Glidden drills up to size 6 and divided into four groups: Pulp Canal Sealer, EndoREZ, Sealapex, and AH Plus. Each group was divided in two subgroups and gutta-percha cylinders 1.5 or 1 mm wide were used, respectively. The roots were mounted in a bacterial leakage model and the system was checked daily during the following 12 wk. Data were analyzed by Log-Rank test and Student t-test. In the thin layer samples, the sealers demonstrated similar results while, in the thick layer samples, AH Plus revealed the best performance. Generally, greater sealer thickness influenced negatively the sealing ability of the root canal filling, except in AH Plus samples.

Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions

OBJECTIVE

The objective of this study was to evaluate periapical repair following retrograde filling using different root-end filling materials.

STUDY DESIGN

After induction of periapical lesions, 48 root canals from dog teeth were partially filled. Endodontic surgery was performed and 3 different materials were used for root-end filling: Sealer 26, Sealapex plus zinc oxide, or mineral trioxide aggregate (MTA). No additional procedures were performed in the control group after partial filling of the root canal. After 180 days, the animals were killed, the maxillas and mandibles were removed, and specimens were submitted for histologic processing.

RESULTS

Histopathologic analysis revealed similar periapical repair for the groups in which Sealer 26, Sealapex plus zinc oxide, and MTA were used (P > .05). The control group showed unsatisfactory periapical repair (P < .05).

CONCLUSION

There was no difference in periapical tissue healing after retrograde filling with the tested materials, which indicates that these 3 root-end filling materials are equally useful.

Sealing ability of three materials in the orifice of root canal systems obturated with gutta-percha

There were 130 single roots randomly assigned to one of 12 experimental or two control groups. Forty specimens each were sealed with 1, 2, 3, or 4 mm of Cavit, ProRoot MTA, or Tetric. After creation of a uniform orifice diameter, the smear layer was removed and the canal systems obturated using warm lateral compaction of gutta-percha (GP). GP was removed to the experimental depth, experimental materials placed in the orifice, and roots submerged in India ink in a vacuum flask. Specimens were demineralized and leakage measured using a 10x stereomicroscope and graded for depth of leakage by one calibrated, blinded rater. There was no significant interaction (p > 0.05) between test materials and orifice depths, nor main effect of orifice depth (p > 0.05). However, there was a statistically significant main effect of test materials with Tetric demonstrating a significantly better seal than Pro Root or Cavit (p < 0.0001) irrespective of orifice depth.

MTA versus Portland cement as repair material for furcal perforations: a laboratory study using a polymicrobial leakage model

AIM

To compare the ability of Portland cement and mineral trioxide aggregate (MTA) to prevent coronal leakage through repaired furcal perforations in molar teeth.

METHODOLOGY

The pulp chambers of 36 human mandibular molar teeth were accessed and the root canal orifices were located. The roots were horizontally sectioned in the middle third. Composite resin was used to fill the root canal orifices and the apical end of the roots. Perforations were created in the centre of the pulp chamber floor using a size 3 round bur. Thirty teeth were divided into two groups (n = 15) and a further six teeth served as controls. In G1, all 15 perforation defects were repaired with MTA while in G2, Portland cement was used. Each tooth was inserted in a silicone tube (bacterial reservoir) with the region containing the perforation protruding through the end. The system was sterilized and placed in a glass flask containing sterile brain heart infusion medium (BHI). The reservoirs were filled with human saliva mixed in BHI and system was incubated at 37 degrees C and checked daily for the appearance of turbidity in the BHI broth during the following 50 days. The leakage data were analysed statistically by a log-rank test (P < 0.05).

RESULTS

Eight (53%) of the 15 samples of the MTA group (G1) and nine (60%) of the 15 samples of the Portland cement group (G2) were fully contaminated at 50 days. There was no statistically significant difference between the two groups (P > 0.05).

CONCLUSION

Portland cement and MTA demonstrated a similar ability to seal furcal perforations.

Analysis of the sealing ability of different obturation techniques in oval-shaped canals: a study using a bacterial leakage model

The aim of this study was to evaluate the sealing ability of 3 obturation techniques in oval canals using a bacterial leakage model. Seventy mandibular incisors with oval canals were selected after buccolingual and mesiodistal radiographs, and divided into three groups. After instrumentation, the canals were obturated respectively by lateral condensation (G1), warm vertical condensation (G2) and Thermafil (G3). Five root canals were not obturated and served as positive controls; five teeth with intact crowns served as negative controls. All teeth were mounted on a 2 chamber apparatus and then exposed to human saliva. The number of days required for the entire contamination of the root canals was recorded, observing the turbidity of the BHI broth, for a period of 100 days. 84.21% of the samples from the lateral condensation group (G1); 84.21% of the samples from the warm vertical condensation group (G2); and 89.47% of the samples from the Thermafil System group (G3) showed no contamination at the end of the study. No statistical significant difference was found among the three techniques. The quality of the apical seal in the three techniques tested was similar.

Periradicular status related to the quality of coronal restorations and root canal fillings in a Brazilian population

OBJECTIVE

This cross-sectional study was undertaken to determine the prevalence of periradicular lesions in root-filled teeth from an urban adult Brazilian population, and to investigate the quality of root canal fillings and coronal restorations and their association with the periradicular status of these teeth.

STUDY DESIGN

Root canal fillings from 2,051 teeth were categorized as adequate or inadequate on the basis of root canal filling length and homogeneity. Coronal restorations from the same teeth were categorized into adequate, inadequate, or absent. Results were analyzed statistically using the chi-squared test.

RESULTS

The overall success rate of root-filled teeth was 49.7%. Cases with adequate endodontic treatment and adequate restorations had a success rate of 71%. When cases with adequate treatment and inadequate restoration were evaluated, the success rate was 65%. Cases with adequate treatment and absent restoration showed a success rate of 48%. Teeth with inadequate treatment combined with adequate restoration yielded a success rate of 38%, whereas the combination of inadequate treatment and inadequate restoration resulted in a success rate of 25%. Teeth with inadequate treatment and absent restoration showed the lowest success rate of this study (18%). Data analysis revealed that when the root canal filling appeared to be adequate, the quality of the restoration did not significantly influence the treatment outcome. However, when a coronal restoration was absent, the success rate of adequately treated canals was significantly reduced. The quality of the coronal restoration significantly affected the outcome of inadequately treated teeth.

CONCLUSIONS

Our results revealed a high prevalence of periradicular lesions in root-filled teeth, which was comparable to that reported in other methodologically compatible studies from diverse geographical locations. In addition, even though the coronal restoration had a significant impact on the periradicular health, the quality of the root canal filling was found to be the most critical factor in this regard.

An In Vitro Comparison of the Sealing Ability of Three Endodontic Sealers Used in Canals with Iatrogenic Enlargement of the Apical Constriction

In cases of disrupted apical constriction effort is made to create an apical stop and subsequently instrument and obturate the canal up to this point. The aim of this study was to in vitro evaluate the sealing ability of three root canal sealers used with the lateral compaction technique in teeth with enlarged constriction. Thirty-six single rooted premolars with straight canals were instrumented up to the apical constriction using a step-back technique. The constriction was enlarged and root canal instrumentation 1.5 mm short of the original working length was performed, to create a new apical stop. Teeth were obturated using lateral compaction technique with either Topseal, Roth 811, or Apexit. Teeth were subjected to area-metric analysis of dye penetration in transverse root sections, up to the most coronal extend of the dye. Sections were studied under the stereomicroscope, digital images were processed and leakage area was estimated. Statistical analysis was performed using Student's t test and Wilcoxon matched-pairs signed-rank test. No gutta-percha was extruded into the space between the apical constriction and the new iatrogenically created constriction. Topseal showed statistical significant less leakage. No significant difference was found between Apexit and Roth 811 (t = 0.99; p = 0.75).

Clinical response to a vacant post space

AIM

To report a case demonstrating a radiolucency of developing adjacent to an unfilled post space.

SUMMARY

A mandibular left first molar was root filled before post-space preparation. The tooth was restored coronally but the post space was left empty, and 14 months later, pain and furcal radiolucency developed. Cleaning, shaping, medicating and filling the post space resulted in the resolution of symptoms and healing of the radiolucency.

KEY LEARNING POINTS

Post space should be prepared under conditions of asepsis. A post space must not be allowed to remain empty when a tooth is restored.