Solubility and biocompatibility of calcium hydroxide-containing root canal sealers

Prognosis of Vital Pulp Therapy on Permanent Dentition: A Systematic Review and Meta-analysis of Randomized Controlled Trials

INTRODUCTION

The aim of this systematic review was to evaluate the existing randomized controlled trials (RCTs) on the safety and efficacy of vital pulp therapy (VPT) and to analyze the outcomes of VPT performed with a variety of pulp-capping materials and techniques.

METHODS

MEDLINE (PubMed), Embase, Cochrane Library, and gray literature were searched (January 2000-March 2021). Study selection and data extraction were performed in duplicate. Eligible RCTs were critically appraised for risk of bias and quality of evidence and were meta-analyzed to estimate the treatment effects.

RESULTS

Fourteen studies were included. The pooled success rate of VPT using contemporary capping materials such as mineral trioxide aggregate (MTA) or calcium silicate-based materials (CSMs) was 93.2% (95% confidence interval [CI], 91.6%-94.9%). Multiple subgroup analyses by different etiologies, procedure types, developmental stages of teeth, and preoperative diagnoses were performed. Analyses presented low certainty of evidence. No significant difference was noted between MTA and CSM at 12 months or a longer follow-up (risk ratio = 0.99; 95% CI, 0.95-1.03) with low certainty of evidence. Laser-assisted VPT failed to show significantly better outcomes than conventional VPT (risk ratio = 1.19; 95% CI, 0.99-1.49) with very low certainty of evidence.

CONCLUSIONS

When MTA or CSM was used as a capping material, VPT was 93% successful. The techniques, etiologies, developmental stages of teeth, and preoperative diagnosis had no significant influence on treatment outcomes. No major adverse effects (except discoloration associated with the use of MTA) were identified. The overall quality of evidence was low.

Biocompatibility of a High-Plasticity, Calcium Silicate-Based, Ready-to-Use Material

The Bio-C Sealer is a recently developed high-plasticity, calcium-silicate-based, ready-to-use material. In the present study, chemical elements of the materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The biocompatibility of the Bio-C Sealer was investigated using cytotoxicity tests and histological responses in the roots of dogs’ teeth. XRD, SEM, and FTIR produced hydrated calcium silicate in the presence of water molecules. In addition, FTIR showed the formation of calcium hydroxide and polyethylene glycol, a dispersing agent. The 1:4 dilutions of Bio-C Sealer presented weaker cytotoxicity than the Calcipex II in an in vitro system using the V-79 cell line. After 90 d, the periradicular tissue response of beagle dog roots was histologically evaluated. Absence of periradicular inflammation was reported in 17 of the 18 roots assessed with the Bio-C Sealer, whereas mature vertical periodontal ligament fibers were observed in the apical root ends filled with the Bio-C Sealer. Based on these results and previous investigations, the Bio-C Sealer is recommended as an effective root-end filling material. These results are relevant for clinicians considering the use of Bio-C Sealer for treating their patients.

Antibacterial Additives in Epoxy Resin-Based Root Canal Sealers: A Focused Review

Dental materials used in root canal treatment have undergone substantial improvements over the past decade. However, one area that still remains to be addressed is the ability of root canal fillings to effectively entomb, kill bacteria, and prevent the formation of a biofilm, all of which will prevent reinfection of the root canal system. Thus far, no published review has analysed the literature on antimicrobial additives to root canal sealers and their influence on physicochemical properties. The aim of this paper was to systematically review the current literature on antimicrobial additives in root canal sealers, their anti-fouling effects, and influence on physicochemical properties. A systematic search was performed in two databases (PubMed and Scopus) to identify studies that investigated the effect of antimicrobial additives in epoxy resin-based root canal sealers. The nature of additives, their antimicrobial effects, methods of antimicrobial testing are critically discussed. The effects on sealer properties have also been reviewed. A total of 31 research papers were reviewed in this work. A variety of antimicrobial agents have been evaluated as additives to epoxy resin-based sealers, including quaternary ammonium compounds, chlorhexidine, calcium hydroxide, iodoform, natural extracts, antibiotics, antifungal drugs, and antimicrobial agent-functionalised nanoparticles. Antimicrobial additives generally improved the antimicrobial effect of epoxy resin-based sealers mainly without deteriorating the physicochemical properties, which mostly remained in accordance with ISO and ANSI/ADA specifications.

Solubility of Root Canal Sealers: A Comparative Study

Introduction

Root canal sealers used in odontological applications are capable of providing an apical seal, thus inhibiting potential bacterial penetration into the periradicular tissues. Since insolubility is the ideal characteristic for a root canal sealer material, in dentistry the sealability of the material depends on its solubility.

Purpose

This study tested the solubility of six different root canal sealers: two ZnOE-based sealers (Endomethasone C and Argoseal), two calcium hydroxide-containing sealers (Bioseal Normal and Acroseal), and two resin-based sealers (AH Plus and MM Seal).

Methods

Ten specimens of each material were prepared using stainless steel ring molds with the same internal diameter and the same height in order to obtain similar samples, and immersed in water. Solubility was determined by using sample weight loss (%) after 24 hours and after 2 months. The test was performed according to the International Standards Organization 6876 standard and the American Dental Association specifications No. 30 and No. 57. Data were statistically analyzed with a one-way analysis of variance test (ANOVA).

Results

The ANOVA test showed significant differences between the various groups. The post-hoc test showed that resin-based root canal sealers had significantly lower solubility percentages than other groups (p<0.05), and showed no difference between them (p>0.05).

Conclusions

All the materials fulfilled the requirements of International Standard 6876 and ANSI/ADA specifications demonstrating a weight loss of less than 3%. Under the conditions of the present study, all root canal sealers were of low solubility, but the lowest solubility percentages were recorded in resin-based root canal sealers, which can be considered virtually insoluble, and thanks to this physical property, ideal for use as endodontic sealer.

Evaluation of the biocompatibility of experimentally manufactured portland cement: An animal study

Objectives: The purpose of this study was to evaluate the biocompatibility of MTA and the experimentally manufactured portland cement (EMPC). Study design: Twenty one Sprague Dawley (SD) rats were allocated to testing of three groups. Group I and Group II included ProRoot MTA and the EMPC. The materials were mixed with distilled water and placed in polyethylene tubes. The tubes were implanted subcutaneously in the dorsal region of the animals. Group III served as control; the implanted polyethylene tubes remained empty. At 7, 14, and 28 days after the implantation, the animals were sacrificed and the implants were removed with the surrounding tissues. The specimens were prepared for histological examination to evaluate the inflammatory response. Results: No significant difference was found between tissue reactions against the tested materials (p>0.05). Also, control group showed similar results (p>0.05). Conclusions: Results suggest that the EMPC has the potential to be used in clinical conditions in which ProRoot MTA is indicated. MTA and the EMPC show comparable biocompatibility when evaluated in vivo. Although the results are supportive for the EMPC, more studies are required before the safe clinical use of the EMPC.

Key words:Mineral trioxide aggregate, portland cement, subcutanous implantation.

3D analyses of interface voids in root canals filled with different sealer materials in combination with warm gutta-percha technique

OBJECTIVES

The aim of the present study was to analyze the formation of voids and gaps in root canals obturated with different sealer materials in combination with warm gutta-percha vertical compaction technique by using BeeFill® 2in1.

MATERIALS AND METHODS

Twenty-four single-rooted teeth were collected, and root canals were prepared by using rotary files. All teeth were randomly allocated into three groups. Each group was obturated by using the BeeFill® 2in1 system in combination with Sealapex (non-eugenol, calcium hydroxide polymeric root canal sealer; Kerr Sybron, USA), RoekoSeal (polydimethylsiloxane-based sealer; Roeko, Germany), or 2Seal (epoxy-amine resin-based sealer; VDW, Germany). Following preparation, all teeth were scanned with a micro-computed tomography (CT) scanner, and a three-dimensional reconstruction of the obturated root canals was performed to analyze the volume of interface voids and gaps in the obturated teeth.

RESULTS

Statistical analysis demonstrated that the silicon-based sealer RoekoSeal induced significantly less voids and gaps than other tested materials. The amount of voids and gaps significantly was higher in the apical region.

CONCLUSIONS

These data indicate that none of the root canal-filled teeth were free of gaps. Teeth obturated with RoekoSeal demonstrated to have the highest quality in terms of voids and gaps formation in combination with the BeeFill® 2in1 obturation system.

CLINICAL RELEVANCE

These findings point to the potential benefit of micro-CT analyses for in vitro evaluation of root canal obturation systems and provide further information about sealer materials used in combination with a warm gutta-percha vertical compaction technique.

Biological compatibility of some types of endodontic calcium hydroxide and glass ionomer cements

The purpose of this work was to evaluate the biological compatibility of the Sealapex, Apexit, Sealer 26 and Ketac Endo endodontic cements. Polyethylene tubes containing these cements were implanted in the subcutaneous tissue of 40 (forty) rats. The animals were sacrificed after 14 and 90 days. A descriptive analysis of the reactions found in the connective tissue by contact with the cements was performed. The magnitude of inflammatory infiltrate, the presence and predominance of cell types and their distribution as to the filling material and reparative phenomena, such as fibroblastic and angioblastic proliferation and formation of fibrous capsules, were subjectively measured. After 90 days, all cements presented statistically significant reduction of the inflammatory reaction, presence of a fibrous tissue capsule in contact with the opening of the tubes containing the filling materials, and reduction of fibroblastic proliferation. Angioblastic proliferation decreased only for the Sealer 26 and Ketac Endo groups. All cements tested were either partially or totally phagocyted, and the mildest inflammatory response was found for the Sealer 26 group at both evaluation periods.

Short-term vs long-term calcium hydroxide therapy after immediate tooth replantation: a histomorphometric study in monkey's teeth

Endodontic treatment is an important step of tooth replantation protocols, but the ideal moment for definitive obturation of replanted teeth has not yet been established. In this study, a histomorphometric analysis was undertaken to evaluate the repair process on immediate replantation of monkey's teeth after calcium hydroxide (CH) therapy for 1 and 6 months followed by root canal filling with a CH-based sealer (Sealapex(®) ). The maxillary and mandibular lateral incisors of five female Cebus apella monkeys were extracted, kept in sterile saline for 15 min, replanted and splinted with stainless steel orthodontic wire and composite resin for 10 days. In Group I (control), definitive root canal filling was performed before tooth extraction. In Groups II and III, CH therapy started after removal of splint, and definitive root canal filling was performed 1 and 6 months later, respectively. The animals were euthanized 9 months after replantation, and specimens were processed for histomorphometric analysis. In all groups, epithelial attachment occurred at the cementoenamel junction or very close to this region; the areas of resorption on root surface had small extension and depth and were repaired by newly formed cementum; and the periodontal ligament was organized. Statistical analysis of the scores obtained for the histomorphometric parameters did not show any statistically significant difference (P = 0.1221) among the groups. The results suggests that when endodontic treatment is initiated 10 days after immediate replantation and an antibiotic regimen is associated, definitive root canal filling can be performed after a short-term CH therapy.

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.

An in vitro Study of Diffusibility and Degradation of Three Calcium Hydroxide Pastes

Aims and objectives : The aim of this in vitro study is to assess the diffusibility and degradation of three calcium hydroxide pastes. Materials and methods : Three pastes were prepared by mixing calcium hydroxide powder with three different vehicles namely water, propylene glycol and CMCP for the investigation. The three pastes were sealed in porcelain caps and immersed in distilled water for the diffusion study. The change in the pH of the surrounding water indicated the rate and degree of diffusion in the degradation study (1 to 7 days, 14th day, 21st day and 30th day). The pastes were exposed to an atmosphere of carbon dioxide in the degradation study to assess the degree to which they can undergo degradation by carbonation. Mordant Black or Solochrome Black indicator was used for the estimation. Results and conclusion : Calcium hydroxide readily diffuses from all the three pastes. Calcium hydroxide diffuses marginally less from a paste made with propylene glycol as compared to CMCP paste. The comparative stability of Ca(OH)2 was studied and the results showed that consistently significant protection is imparted to Ca(OH)2 by CMCP over widely ranging periods.

Physicochemical properties, sealing ability, bond strength and cytotoxicity of a new dimethacrylate-based root canal sealer

BACKGROUND/PURPOSE

Resin-based root canal sealer can bond to dentin and establish a hermetic seal. The aim of this study was to evaluate the physicochemical properties, sealing ability, cytotoxicity and bond strength of a new resin-based root canal sealer (NRCS).

METHODS

The physicochemical properties were assessed by the flow, setting time, solubility, film thickness, radiopacity and dimensional changes. Sixty premolar root samples were filled with either Resilon/NRCS or Resilon/Epiphany and sectioned perpendicularly at the long axis at 2 mm below the cemento-enamel junction into 1-mm serial slices. The bond strength was tested by a universal testing machine. The glucose microleakage model was used to test the sealing ability. Elutes of NRCS and Epiphany were co-cultured with human periodontal ligament cells to test the cytotoxicity.

RESULTS

All the physicochemical properties of NRCS conformed to ISO 6876:2001(E). The root samples filled with Resilon/NRCS had significantly less leakage (p < 0.01) and greater bond strength (p < 0.001) than the Resilon/Epiphany group had. Environmental scanning electron microscopy showed that Resilon/NRCS filling material was intimately bonded to the root dentin. Although NRCS was slightly toxic to human periodontal ligament cells, its cytotoxicity was significantly less than that of Epiphany (p < 0.01)

CONCLUSION

NRCS has better physicochemical and sealing properties, as well as lower cytotoxicity and microleakage than Epiphany has.

Antibacterial activity of endodontic sealers by modified direct contact test against Enterococcus faecalis

INTRODUCTION

The antibacterial effectiveness of 7 different endodontic sealers, AH Plus, Apexit Plus, iRoot SP, Tubli Seal, Sealapex, Epiphany SE, and EndoRez against Enterococcus faecalis was studied in vitro.

METHODS

A modified direct contact test was used. Bacteria in suspension were exposed to the materials for 2-60 minutes by using sealers that were freshly mixed or set for 1, 3, and 7 days. The pH values and contact angles of sterile water on sealers at different times after setting were also measured.

RESULTS

Fresh iRoot SP killed all bacteria in 2 minutes, AH Plus in 5 minutes, EndoRez in 20 minutes, and Sealapex and Epiphany in 60 minutes. Freshly mixed Apexit Plus and Tubli Seal failed to kill all bacteria at 60 minutes. For 1-day and 3-day samples, iRoot SP and EndoRez had the strongest antibacterial activity, followed by Sealapex and Epiphany; Tubli Seal and AH Plus did n'ot show any significant antibacterial activity. Of all the samples, Apexit Plus had the lowest antimicrobial activity. The pH of the sealers could not alone explain their antibacterial effect.

CONCLUSIONS

Fresh iRoot SP, AH Plus, and EndoRez killed E. faecalis effectively. IRoot SP and EndoRez continued to be effective for 3 and 7 days after mixing. Sealapex and EndoRez were the only ones with antimicrobial activity even at 7 days after mixing.

Calcium hydroxide-based root canal sealers: a review

The aim of this review was to consider laboratory experiments and clinical studies of calcium hydroxide-based root canal sealers. An extensive search of the endodontic literature was made to identify publications related to calcium hydroxide-based root canal sealers. The articles were assessed for the outcome of laboratory and clinical studies on their biological properties and physical characteristics. Comparative studies with other sealers were also considered. Several studies were evaluated covering different properties of calcium hydroxide-based sealers including physical properties, biocompatibility, leakage, adhesion, solubility, antibacterial properties, and periapical healing effect. Calcium hydroxide-based root canal sealers have a variety of physical and biological properties. Comparative studies reveal their mild cytotoxicity, but their antibacterial effects are variable. Further research is required to establish the tissue healing properties of calcium hydroxide in root canal sealers.

In vivo evaluation of the biocompatibility of a new resin-based obturation system

OBJECTIVE

The aim of this study was to evaluate the in vivo biocompatibility of the new resin-based Epiphany-Resilon root canal filling system after implantation in rat connective tissue.

STUDY DESIGN

Thirty-six female Wistar albino rats, 9 months old, weighing 200 to 220 g, were used to evaluate the biocompatibility. Four subcutaneous pockets were created in the back of the rats, and each material (Resilon, gutta-percha, a Teflon tube containing Epiphany, and an empty Teflon tube) was implanted into a specific dorsal site. The empty Teflon tubes were used as control. After 1, 4, and 8 weeks, the implants were removed with the surrounding tissues. The inflammatory tissue reactions were graded after a histopathologic examination.

RESULTS

At each time period, there was practically no difference in the reaction of all the implant materials (P > .05). The intensity of the reaction had diminished by the 4-week observation period, and this reduction continued through the 8-week observation period.

CONCLUSION

All the tested materials showed an acceptable biocompatibility.

Endodontic materials

This article presents a review of materials currently used in the practice of endodontics. Current endodontic materials include those that have been thoroughly tested by scientific investigation, clinical usage, and time, as well as others that are the result of new knowledge in the field of dental materials. Article sections are devoted to obturation materials, sealers, irrigation materials, smear layer removal, root-end filling materials, and intracanal medicaments. Knowing the particular qualities of materials can aid the clinician in choosing those that are appropriate for a given situation. Properties, components, and rationale for the materials' use are presented to aid the clinician in choosing materials for a particular need.

In vitro study assessing apical leakage of sealer-only backfills in root canals of primary teeth

AIM

To assess the sealing ability of zinc oxide-eugenol (ZOE), Apexit, and Sealapex used as sealer-only backfills in root canals of primary teeth using the high-pressure replica technique.

METHODOLOGY

Two hundred and seventy root canals of deciduous molars as well as primary anterior teeth were randomly assigned to three groups (n=90). Root canals were prepared to size 35 and filled with either zinc oxide-eugenol (ZOE), Apexit, or Sealapex using a lentulo filler. Twenty-four hours after setting of the materials the roots were nail-varnished (except for the apical tip), and half of the specimens (n=45) were penetrated by a coloured (rhodamine B) epoxy resin. The resin was infiltated into the pores and cavities of the teeth in a high-pressure vessel. The remaining groups (n=45) were stored in 100% humidity, and infiltration of the resin followed after 40d. Apical leakage was assessed by means of a grinding technique using eight steps of 0.5mm each.

RESULTS

ZOE and Apexit failed to seal the root canals in both subgroups. This was significantly different from the root canals filled with Sealapex where in both subgroups some 30% of the specimens revealed a tight seal up to a distance of 2.9mm of the apex.

CONCLUSIONS

Under the conditions of this study it can be concluded that Sealapex shows less leakage than ZOE and Apexit. With regard to the three materials tested, Sealapex should be a viable alternative for sealer-only obturation of pulpectomized primary teeth. The high-pressure replica technique seems to be suitable for assessing leakage of root canal filling materials.

A 1-year follow-up study on leakage of single-cone fillings with RoekoRSA sealer

OBJECTIVE

The aim of this study was to measure long-term leakage along single cone (SC) fillings.

STUDY DESIGN

Two groups of canines (n = 30) were prepared and a size 55 file was the apical master file. Step-back was performed using files of sizes 60, 70, and 80. The canals were filled by the single cone technique using RoekoRSA as sealer. To place sealer into each canal, a bidirectional spiral was used in 1 group, whereas a gutta-percha cone was used in the other group. Immediately after root filling, the coronal portion of root filling was removed by postspace preparation. Leakage along the 4 mm remaining apical root filling was measured after 1 week and again after 1 year using a fluid transport model. Ten additional canine roots were prepared and filled with gutta-percha cones without sealer, serving as positive controls. Occurrence of apical extrusion of materials was recorded.

RESULTS

The apical root filling in all 60 canine roots did not show leakage either at 1 week or at 1 year. All 10 positive controls showed gross leakage (>20 muL/h). In no case gutta-percha extruded through the apical foramen. Sealer extruded apically in 88% of the roots where a gutta-percha cone was used to introduce sealer, whereas in 28% of the roots where a bidirectional spiral was used to introduce sealer (by chi-square test, P < .05).

CONCLUSION

In wide and straight canals, SC fillings with RoekoRSA sealer prevented fluid transport for 1 year. Using bidirectional spiral to place sealer reduced sealer extrusion under the conditions of this experiment.

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).

Endodontics: Part 5 Basic instruments and materials for root canal treatment

In this part the basic endodontic instruments necessary for effective root canal treatment are described. The properties of, and manufacturer's claims for, new instruments and techniques may be compared to these basic principles before they are purchased and introduced to clinical practice. Having the correct instruments for different clinical situations may make treatment both more efficient and more effective.

Solubility of root-canal sealers in water and artificial saliva

AIM

To compare the weight loss of eight different root-canal sealers in water and in artificial saliva with different pH values.

METHODOLOGY

For standardized samples (n = 12 per group), ring moulds were filled with epoxy resin (AH 26, AH Plus)-, silicone (RSA RoekoSeal)-, calcium hydroxide (Apexit, Sealapex)-, zinc oxide-eugenol (Aptal-Harz)-, glass-ionomer (Ketac Endo)- and polyketone (Diaket)-based sealers. These samples were immersed in double-distilled water or artificial saliva with different pH values (7.0, 5.7 and 4.5) for 30 s, 1 min, 2 min, 5 min, 10 min, 20 min, 1 h, 2 h, 10 h, 24 h, 48 h, 72 h, 14 days and 28 days. Mean loss of weight was determined and analysed statistically using a one-way anova and Student-Newman-Keuls test for all pairwise comparisons.

RESULTS

Most sealers were of low solubility, although Sealapex, Aptal-Harz and Ketac Endo showed a marked weight loss in all liquids. Even after 28 days of storage in water, AH 26, AH Plus, RSA RoekoSeal, and Diaket showed less than 3% weight loss. At exposure times greater than 14 days, Sealapex showed the significantly greatest weight loss of all sealers tested (P < 0.05). Aptal-Harz and Ketac Endo were significantly more soluble in saliva (pH 4.5) than in water (P < 0.05).

CONCLUSIONS

Under the conditions of the present study, AH Plus showed the least weight loss of all sealers tested, independent of the solubility medium used. Sealapex, Aptal-Harz and Ketac Endo had a marked weight loss in all liquids.

The effect of using an inverted master cone in a lateral compaction technique on the density of the gutta-percha fill

OBJECTIVE

We sought to measure and calculate the percentage of the gutta-percha-filled area in the apical root canal after the use of a standardized or inverted master cone in cold lateral compaction.Study design Two groups of extracted mandibular premolars with a single canal were instrumented with instruments of the same size; furthermore, they were obturated with laterally compacted gutta-percha cones with AH26 used as a sealer. In the first group, a standardized master cone was used with its narrow end in an apical position, whereas in the other group, an inverted master cone was used with its wide end in an apical position. The 2 master cones had the same apical diameter and fit in the apical canal. After lateral compaction, horizontal sections were cut at a level 3 and 5 mm from the apex of each filled tooth. Photographs of the sections were taken by using a microscope equipped with a digital camera; the photos were then scanned as tagged-image file format images. The cross-sectional area of the canal and the gutta-percha were measured by using an image-analysis program. The percentage of gutta-percha-filled area was calculated.

RESULTS

At both levels, the inverted master cone produced a significantly higher percentage, statistically, of gutta-percha-filled area than did the standardized master cone (P =.001 at 3 mm; P =.012 at 5 mm).

CONCLUSION

The use of an inverted master cone in cold lateral compaction may facilitate the apical placement of accessory cones, significantly increasing the volume of gutta-percha while reducing the volume of sealer in the apical root canal.

Comparison of 6 different gutta-percha techniques (part II): Thermafil, JS Quick-Fill, Soft Core, Microseal, System B, and lateral condensation

OBJECTIVES

In this in vitro study, the core-to-sealer ratios were calculated for 6 different gutta-percha techniques: Thermafil, JS Quick-Fill, Soft Core, Microseal, System B, and lateral condensation. The core consisted of gutta-percha or gutta-percha and carrier.

STUDY DESIGN

The sealer-to-core ratios for the Thermafil, JS Quick-Fill, System B, and lateral condensation techniques were published previously. In this study, the sealer-to-core ratio for Microseal and Soft Core techniques was investigated. For this purpose, 20 teeth filled by using the Soft Core or the Microseal technique were embedded in resin and sectioned horizontally at 1, 2, 3, and 4 mm from the anatomic apex. Photographs were taken of each section, and the total area of the canals filled with core material or sealer was calculated.

RESULTS

Once all results were compiled, it became clear that core techniques (Thermafil, JS Quick-Fill, and Soft Core) produced higher gutta-percha content than the Microseal, System B, and lateral condensation techniques (P <.05). The lateral condensation technique produced the least gutta-percha content (P <.05).

CONCLUSION

Thermafil, JS Quick-Fill, and Soft Core were found to be superior to the Microseal, System B, and lateral condensation techniques in terms of the gutta-percha-to-sealer ratio.

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 2. Root-canal-filling materials

Root-canal-filling materials are either placed directly onto vital periapical tissues or may leach through dentine. The tissue response to these materials therefore becomes important and may influence the outcome of endodontic treatment. This paper is a review of the biocompatibility of contemporary orthograde and retrograde root-canal-filling materials.

Adhesion of endodontic sealers to dentin and gutta-percha

Adhesion of endodontic sealers to dentin and gutta-percha offers clues into their interaction with the wall of the root canal and the filling material. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH 26, an epoxy resin-based system; and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 24 h, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman-Keuls test at alpha = 0.05. The results indicated that sealant bond strengths to dentin (from lowest to highest mean +/- SD, n = 10) were: Kerr 0.13 +/- 0.02; Sealapex 0.30 +/- 0.08; Ketac-Endo 0.80 +/- 0.24; AH 26 2.06 +/- 0.53 MPa. The latter two were significantly different (p < 0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from lowest to highest mean +/- SD, n = 10) were: Ketac-Endo 0.19 +/- 0.01; Sealapex 0.22 +/- 0.01; Kerr 1.07 +/- 0.19; AH 26 2.93 +/- 0.29 MPa. AH 26 gave the significantly highest bonds to gutta-percha.

A preliminary study of the percentage of gutta-percha-filled area in the apical canal filled with vertically compacted warm gutta-percha

AIM

The aim of this study was to determine the influence of the width of apical root canals and the depth of heat application during warm vertical compaction on the percentage of gutta-percha-filled area (PGFA) in the apical root canal.

METHODOLOGY

Two groups of extracted human canines (total 60) were instrumented and filled with vertically compacted warm gutta-percha up to the apical foramen (AF). Using the Touch 'n Heat device heat was applied 4 mm from the AP in one group and 2 mm in the other. The number of teeth with gutta-percha extrusion was recorded. A horizontal section was cut 1.5 mm from the AF of each tooth. The cross-sectional area of the canal and the gutta-percha was measured using an image-analysis programme. The PGFA was then calculated. Multiple linear regression was performed to investigate the association between the experimental variables and the PGFA, and the occurrence of gutta-percha extrusion.

RESULTS

A significant association was seen between the depth of heat application and the PGFA (P= 0.000), and between the canal area and the PGFA (P= 0.038). The average PGFA reached 96.1% when heated to 2 mm, as compared with 87.0% when heated to 4 mm. PGFAs were lower in wide apical canals than in small canals. Gutta-percha extruded in seven teeth (12%) and was independent of experimental variables.

CONCLUSIONS

After warm vertical compaction, the quality of adaptation of gutta-percha to the wall of the apical root canal varies; the influencing factors in this study were the depth of heat application and the width of the apical root canal.

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

OBJECTIVE

The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide-based root canal dressings and 2 root canal sealers.

STUDY DESIGN

Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an endodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair.

RESULTS

Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus.

CONCLUSIONS

The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.

Clinical performance of 3 endodontic sealers

OBJECTIVE

Calcium hydroxide is used in endodontics as an interappointment dressing. Its inclusion in salicylate resin or zinc oxide-eugenol-based sealers for filling root canals also may lead to a better treatment outcome. The purpose of the present study was to compare the clinical/radiographic treatment outcome of 3 sealers, 2 of which contain calcium hydroxide.

STUDY DESIGN

Two hundred and four teeth underwent a standardized endodontic treatment regimen and were assigned to 1 of 3 groups at the time of root filling: group PS, teeth filled with gutta-percha and Procosol sealer; group CR, teeth filled with gutta-percha and CRCS sealer; and group SA, teeth filled with gutta-percha and Sealapex sealer. The results of the treatment were assessed yearly for up to 4 years by clinical and radiologic (periapical index scores) controls. The ridit statistic (r) was used to compare PAI scores among the groups.

RESULTS

The overall treatment results were comparable with, but slightly poorer than, results previously obtained from patients seen at the Dental School at the University of Oslo. During the first year after filling, the mean ridit value decreased from .51 +/- .039 to .31 +/- .042 (Deltar = .20) in the SA group. Corresponding values went from .43 +/- .030 to .38 +/- .035 (Deltar = .05) in the PS group and from 37 +/- .045 to .34 +/- .050 (Deltar = .03) in the CR group. At the 2-year examination, teeth in group SA had slightly better periapical conditions (r =.22 +/-.045) than did teeth in group PA (r = .30 +/- .037) or in group CR (r = .30 +/- 052). The difference was statistically significant at P = .01. By years 3 and 4, no significant difference among the groups was detected.

CONCLUSIONS

The overall influence of the sealer on treatment outcome was small. Root fillings with salicylate resin containing Ca(OH)2 may support more rapid healing of apical periodontitis or operative trauma, but the results after 3 and 4 years were as good for zinc oxide-eugenol-based sealers with or without Ca(OH)2.

Biocompatibility of root canal filling materials

Results of in vitro and in vivo studies clearly indicate that some endodontic sealers may cause local and systemic adverse effects. Though occasionally contradictory data has been reported from various authors, it may be concluded that zinc-oxide-eugenol sealers possess a marked cytotoxic and tissue-irritating potency. Most Ca(OH)2-based materials, however, were biocompatible. Genotoxic effects have been observed with sealers releasing paraformaldehyde or containing mutagenic substances, such as bisphenol-A-diglycidyl-ether or its derivatives. It cannot be excluded that these materials may pose a systemic risk because formaldehyde is rapidly distributed systemically following its application into the pulp cavity. Furthermore an increasing number of cases with an aspergillosis of the maxillary sinus have been observed which were mainly caused by zinc-releasing endodontic sealers. Overall, it is recommended that for endodontic practice, sealers that have been found to be biocompatible in a "mixed bag" of various in vitro and in vivo tests, be selected. From this point of view, ZnOE-sealers should no longer be used for root canal fillings. This recommendation applies also to sealers containing paraformaldehyde or generating this substance during their setting reaction. More experimental and clinical studies are necessary to elucidate whether new materials, such as mineral trioxide aggregate (MTA) or calcium phosphate cement, will be biocompatible alternatives in the future.

Cytotoxicity of root canal filling materials to three different human cell lines

The aim of this study was to investigate the biological compatibility of five root canal sealers (Sealapex, Endion, Super-EBA, Ketac-Endo, and AH Plus) and regular and calcium hydroxide-based gutta-percha in three different human cell lines. Cultures without root canal sealers were used as controls. Cell growth, cell morphology, cell viability, protein content of the cells, and prostaglandin E2 (PGE2) release were used as parameters to determine the cytotoxicity of the materials. The protein content of the three cell lines--nasal fibroblasts, gingival fibroblasts, and epithelial tumor cells--was significantly reduced (p < or = 0.001) by all materials tested. Determinations of PGE2 release showed significant material specific differences. No significant increased PGE2 release values were found with Sealapex, Endion, and Super-EBA. On the contrary significantly increased PGE2 levels were measured with Ketac Endo, AH Plus, regular and calcium hydroxide-based gutta-percha points (p < or = 0.001).

Diminished leakage along root canals filled with gutta-percha without sealer over time: a laboratory study

AIM

The aim of this study was to investigate the long-term seal of gutta-percha (GP) without sealer.

METHODOLOGY

Extracted human maxillary central incisors were prepared and obturated using heat- or chloroform-softened GP only, or GP in combination with a root canal sealer. Leakage along root fillings was measured at 48 h and after a period of 6 months using a fluid transport model.

RESULTS

At 48 h the GP-filled roots without sealer leaked more than the control roots filled with GP and sealer (P < 0.0001). At 6 months a significant reduction in leakage was found in the GP-only groups (P < 0.05 for both heat- and chloroform-softened GP). After 6 months, roots filled by vertical condensation of GP-only had similar leakage as vertically condensed GP with a sealer (P > 0.05).

CONCLUSIONS

The long-term seal of root fillings is affected by the volume change of both GP and sealer. Leakage reduction due to expansion of GP may compensate to a certain extent for leakage that may occur from sealer dissolution.

A new method for the quantitative analysis of endodontic microleakage

The aim of this in vitro study was to evaluate the apical seal obtained with three commonly used root canal sealing cements: Sealapex, AH Plus or Topseal, and Sealite, using a new method based on the quantitative analysis of 125I-radiolabeled lysozyme penetration. One hundred thirteen teeth with straight single root canals were instrumented to master apical point #25/30. These were divided into three groups: (i) negative control (4 roots) covered with two layers of nail polish, (ii) test group (105 roots) obturated by laterally condensed guttapercha with the three cements; and (iii) positive control (4 roots) obturated without cement. The groups were then immersed in 125I lysozyme solution for a period of 1, 7, 14, or 28 days. After removal, six sections of 0.8 mm length each were made of each root with a fine diamond wire. Each section was analyzed for activity by a gamma counter, corrected for decay, and used to quantify protein penetration. Leakage was high in the positive control and almost negligible in the negative control. AH Plus (Topseal) and Sealapex showed similar leakage behavior over time, with AH Plus (Topseal) performing better. Sealite showed acceptable leakage up until day 14, after which a large increase occurred, presumably due to three-dimensional instability.

Tissue response to an epoxy resin-based root canal sealer

The objective of the present study was to evaluate two different types of root canal sealers: AH Plus (an epoxy resin-based sealer) and Fill Canal (a zinc oxide-eugenol based sealer). A total of 34 root canals with vital pulp from dogs' premolars were used. After instrumentation, the root canals were filled with gutta-percha and AH Plus or gutta-percha and Fill Canal sealers using a classical technique of lateral condensation. After histological processing, the sections were stained with hematoxylineosin or Mallory's trichrome stain. Inflammatory cells or areas of necrosis were not associated with AH Plus. Hard tissue formation apically to the material was observed in 14 specimens. The Fill Canal sealer presented an inflammatory response of moderate intensity in the periapical region, mainly adjacent to the material.

Influence of smear layer on depth of penetration of three endodontic sealers: an SEM study

The purpose of this study was to examine the effect of the smear layer on the penetration depth of Sealapex, Roth 811, and CRCS root canal sealers into the dentinal tubules. Forty recently extracted, human single-rooted teeth were used. The crowns were cut and removed at the cemento-enamel junction level and the root canals were prepared to a #60 K-file. The teeth were then randomly divided into two groups of 20, group A and group B. The smear layer was removed from all teeth in group A with EDTA and NaOCl. The smear layer remained in all teeth in group B. Two roots in each group were used as controls. Six roots from each group were obturated with Roth 811 sealer and gutta-percha through lateral condensation. The same process was repeated using sealers CRCS and Sealapex. Each root was then divided in two and prepared for scanning electron microscope observation. The removal of the smear layer allowed penetration of all three sealers into the dentinal tubules to a depth of between 35 microns and 80 microns. Although the CRCS sealer penetrated only up to the 35 mm point, it offered better or complete obturation of the dentinal tubules. The presence of smear layer at the root canal walls obstructed the penetration of all sealers into the dentinal tubules.

In vivo comparison of the biocompatibility of two root canal sealers implanted into the subcutaneous connective tissue of rats

The purpose of this study was to evaluate the in vivo biocompatibility of Apexit (a calcium hydroxide) and Pulp Canal Sealer (a classic zinc oxide-eugenol), root canal sealers, after implantation in rat connective tissue. Forty-four white female Wistar-Furth rats were used. Each sealer was placed in Teflon tubes and implanted into specific dorsal subdermal tissues sites. Implants were removed after 5, 15, 60, and 120 days; fixed; and histologically prepared for microscopical evaluation. Severe inflammatory reactions with differing extensions of necrosis were observed with Apexit on the 5th and 15th days. The intensity of the reaction had diminished by the 60th day, and this reduction continued progressively through the 120th day. It was characterized by the presence of connective tissue with a few macrophages. Moderate to severe inflammation with confined areas of necrosis was observed in the Pulp Canal Sealer specimens on the 5th day. The intensity of the reaction diminished by the 15th, 60th, and 120th days, but remained slightly greater than Apexit through longterm observation periods.

Antibacterial activity of calcium hydroxide-containing endodontic sealers on Enterococcus faecalis in vitro

Antimicrobial activity of endodontic sealers is an important factor in the prognosis of root canal treatment. The aim of this study was to analyse the antimicrobial activity of calcium hydroxide-containing endodontic sealers, Sealapex (SA) and CRCS compared to a ZOE-containing sealer, Roth's cement. The sealers were mixed and placed on the side wall of microtitre plate wells. A 10 microL suspension of Enterococcus faecalis was added to the surface of the sealers 1 h, 24 h, or 7 days after mixture. Bacteria were allowed to come into contact with the sealers for 1 h at 37 degrees C. Fresh media was then added and bacterial growth was measured every 30 min for 16 h. The results showed that in 1-hour-old mixture, CRCS and Roth's cement had a significantly better antimicrobial effect than SA. In 24-hour-old mixtures, ZOE-based sealer showed a more potent antimicrobial activity than calcium hydroxide-containing sealers, whereas SA showed a significantly better antimicrobial effect in the 7-day-old mixture. The antimicrobial activity of each tested sealer changes differently with the time interval between mixing and testing, suggesting different physicochemical properties and potentially diverse clinical applications.

Effect of sealer thickness on long-term sealing ability: a 2-year follow-up study

Long-term sealing ability of root-canal sealer is of clinical importance. We compared the performance of five sealers and a dentine bonding agent, at thicknesses of 0.05 mm (thin layer) and 0.3 mm (thick layer), in 212 standard human root specimens, before and after storage in water for 2 years. Thick layers of Roth and Pulp Canal Sealer EWT (PCS-EWT) allowed more leakage than did thin layers (P = 0.0000, 0.0358 for Roth and PCS-EWT, respectively) whereas no significant difference was found between the thin and thick layers for AH26, Ketac-Endo, Sealapex and J&J Bonding Agent. The pooled results of the thin and thick layers, which have clinical relevance, showed that after storing the specimens in water for 2 years, AH26, Sealapex, Ketac-Endo and PCS-EWT leaked more than before storage in water (P = 0.0008, 0.0000, 0.0035, 0.0257 for AH26, Sealapex, Ketac-Endo and PCS-EWT respectively), and that J&J Bonding Agent allowed less leakage and PCS-EWT more leakage than the other four sealers (P = 0.0000).