Comparison of Sealer Penetration Using the EndoVac Irrigation System and Conventional Needle Root Canal Irrigation

Introduction

The aim of this study was to compare the effect of the EndoVac irrigation system (SybronEndo, Orange, CA) and conventional endodontic needle irrigation on sealer penetration into dentinal tubules.

Methods

Forty single-rooted, recently extracted human maxillary central incisors were randomly divided into 2 groups according to the irrigation technique used: conventional endodontic needle irrigation and EndoVac irrigation. All teeth were instrumented using the ProFile rotary system (Dentsply Maillefer, Ballaigues, Switzerland) and obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) labeled with fluorescent dye. Transverse sections at 1, 3, and 5 mm from the root apex were examined using confocal laser scanning microscopy. The total percentage and maximum depth of sealer penetration were then measured.

Results

Mann-Whitney test results showed that EndoVac irrigation resulted in a significantly higher percentage of sealer penetration than conventional irrigation at both the 1- and 3-mm levels (P < .05). However, no difference was found at the 5-mm level. The 5-mm sections in each group showed a significantly higher percentage and maximum depth of sealer penetration than did the 1- and 3-mm sections (P < .05).

Conclusions

The EndoVac irrigation system significantly improved the sealer penetration at the 1- to 3-mm level over that of conventional endodontic needle irrigation.     

Dentin Extends the Antibacterial Effect of Endodontic Sealers against Enterococcus faecalis Biofilms

Introduction

The purpose of this study was to evaluate the antimicrobial effects of root canal sealers on Enterococcus faecalis biofilms in dentinal tubules by using a novel dentin infection model.

Methods

Cells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion broth for 3 weeks. An equal thickness of AH Plus, Endosequence BC sealer (BC sealer), and pulp canal sealer EWT (PCEWT) was placed on the root canal wall of the dentin specimens for 1, 7, and 30 days in humid conditions at 37°C. Gutta-percha and water were used in a similar manner as the tested sealers. The proportions of dead and live bacteria inside the dentinal tubules after exposure to root canal sealers were assessed by confocal laser scanning microscopy.

Results

Significantly more bacteria were killed in the 3 sealer groups than in the 2 control groups (P < .05). BC sealer and AH Plus resulted in significantly more dead cells than PCEWT did. There was no statistically significant difference between BC sealer and AH Plus at any time point (P > .05). Thirty days of exposure to BC sealer and AH Plus resulted in significantly more dead bacteria in dentin than 7-day and 1-day exposures in the biofilms, whereas no statistically significant increase of the proportion of dead bacteria was detected between 7-day and 30-day PCEWT (P > .05).

Conclusions

The 3 endodontic root canal sealers had antibacterial effects against E. faecalis in the dentinal tubules. BC sealer and AH Plus had superior antibacterial effects compared with PCEWT. The antibacterial effects of sealers in dentinal tubules continued after setting.     

Sealer Penetration into Dentinal Tubules in the Presence or Absence of Smear Layer: A Confocal Laser Scanning Microscopic Study

Introduction

The aim of this study was to test the dentinal tubule penetration of AH26 (Dentsply DeTrey, Konstanz, Germany) and MTA Fillapex (Angelus, Londrina, PR, Brazil) in instrumented root canals obturated by using cold lateral compaction or warm vertical compaction techniques in either the presence or absence of the smear layer.

Methods

Forty-five extracted single-rooted human mandibular premolar teeth were used. The crowns were removed, and the root canals were instrumented by using the Self-Adjusting File (ReDent-Nova, Ra'anana, Israel) with continuous sodium hypochlorite (2.6%) irrigation. Final irrigation was either with 5% EDTA or with sodium hypochlorite. The canals were dried and obturated by using rhodamine B–labeled AH26 or MTA Fillapex in combination with the cold lateral compaction or the warm vertical compaction technique. After setting, the roots were sectioned horizontally at 4-, 8-, and 12-mm distances from the apical tip. On each section, sealer penetration in the dentinal tubules was measured by using confocal laser scanning microscopy.

Results

Regardless of the usage of EDTA, MTA Fillapex, compared with AH26, was associated with greater sealer penetration when used with the cold lateral compaction technique, and, conversely, AH26, compared with MTA Fillapex, was associated with greater sealer penetration when used with the warm vertical compaction technique (P < .05). Removal of the smear layer increased the penetration depth of MTA Fillapex used with the cold lateral compaction technique (P < .05); however, it had no significant effect on the penetration depth of AH26.

Conclusions

Greater sealer penetration could be achieved with either the MTA Fillapex–cold lateral compaction combination or with the AH26–warm vertical compaction combination. Smear layer removal was critical for the penetration of MTA Fillapex; however, the same did not hold for AH26.     

Penetration of Epiphany, Epiphany self-etch, and AH Plus into dentinal tubules: a scanning electron microscopy study

Introduction

The purpose of this study was to measure the average depth of dentinal tubule sealer penetration in the middle third of teeth obturated with gutta-percha/AH Plus (Dentsply, DeTrey, Konstanz, Germany), Resilon/Epiphany (Pentron Clinical Technologies, Wallingford, CT), and Resilon/Epiphany self-etch (SE) using scanning electron microscopy (SEM).

Methods

The root canals of 36 extracted single-rooted human teeth were prepared and randomly divided into three groups. Obturations were performed with the following filling materials using the lateral compaction technique: group 1, gutta-percha/AH Plus; group 2, Resilon/Epiphany; and group 3, Resilon/Epiphany SE. The specimens were prepared for SEM examination. The average depth of sealer penetration into the dentinal tubules was measured. Data were analyzed by one-way analysis of variance and a post hoc Tukey test.

Results

The mean (± standard deviation) values for the average depth of sealer penetration in the middle third of the roots were 22.07 ± 6.92 μm, 31.56 ± 6.80 μm, and 21.50 ± 9.25 μm for AH Plus, Epiphany, and Epiphany SE, respectively. The average penetration depth of Epiphany was significantly higher than that of Epiphany SE and AH Plus (P < .05). There was no significant difference between the penetration depth of Epiphany SE and AH Plus (P > .05).

Conclusions

It could be concluded that the average penetration for Epiphany into dentinal tubules within the middle third of the roots was significantly deeper than that of Epiphany SE and AH Plus.     

Influence of Ultrasonic Activation of 4 Root Canal Sealers on the Filling Quality

Introduction

The purpose of this study was to evaluate the effects of ultrasonic activation on the filling quality (intratubular sealer penetration, interfacial adaptation, and presence of voids) of 4 epoxy resin–based sealers.

Methods

Eighty-four extracted human canines were divided into 4 groups (n = 20) according to the sealer used to obturate the root canals instrumented with F5 ProTaper instruments (50/05) (Dentsply Maillefer, Ballaigues, Switzerland). The canals were filled by the lateral compaction technique. Previously, the sealers were labeled with rhodamine B dye to allow analysis under a confocal microscope. At the time of obturation, the specimens were divided again into 2 groups (n = 10) according to the ultrasonic activation of the sealers: ultrasonically activated and nonultrasonically activated groups. All samples were sectioned at 2, 4, and 6 mm from the apex. The percentages of voids, gaps, and dentinal sealer penetration segments of the canal were analyzed.

Results

Regarding the sealer penetration segments, there was a significant increase for the AH Plus (Dentsply Maillefer), Acroseal (Specialités Septodont, Saint Maur-des-Fossés, France), and Sealer 26 (Dentsply Maillefer) at the 4-mm level and the AH Plus and Sealer 26 at the 6-mm level with ultrasonic activation (P < .05). Concerning the gaps, the ultrasonic activation promoted a smaller presence for all sealers at the 4- and 6-mm levels (P < .05). No statistical significant differences were found for the percentages of voids (P < .05).

Conclusions

The use of ultrasonic activation of an epoxy resin–based sealer promoted greater dentinal sealer penetration and less presence of gaps.     

Extension of Bactericidal Effect of Sodium Hypochlorite into Dentinal Tubules

Introduction

The aim of this study was to determine the extent of disinfection mediated by 2 concentrations of sodium hypochlorite for bacteria-laden dentin wall of a root canal.

Methods

A dual-species film, Enterococcus faecalis and Porphyromonas gingivalis, was cultivated on root canal dentin for 7 days. The canal wall was irrigated with 0.5% or 3% sodium hypochlorite (n = 8 each), with a control group (n = 2) irrigated with sterile saline. The roots were then split horizontally at 5-, 7-, and 9-mm levels from root apex and examined under confocal laser scanning microscope and then scanning electron microscope. The proportions of viable cells situated on different depths into root canal dentin were compared at a significance level of P = .05.

Results

Both concentrations of sodium hypochlorite significantly reduced the amount of live bacteria in the most superficial layer (first 0.1 mm) of root canal dentin, compared with the control; however, the difference was not significant between the 2 concentrations. For the next 2 layers (0.1–0.3 mm into dentinal tubules), irrigation with 3% hypochlorite resulted in significantly lower amounts of viable bacteria than 0.5% hypochlorite or saline. No significant difference between 0.5% or 3% sodium hypochlorite and the positive control was observed in deeper (>0.3 mm) regions into the root canal wall.

Conclusions

Increasing the concentration of sodium hypochlorite improves the penetration depth of its antibacterial action into dentinal tubules, but that seemed unable to completely eradicate bacteria residing there. Total elimination of bacteria from dentinal tubules cannot be achieved by irrigation with sodium hypochlorite alone.     

Effect of different surface treatments on In-Ceram Alumina roughness. An AFM study

Objectives

The aim of this study was to evaluate the influence of different treatments on the surface roughness of In-Ceram Alumina (VITA, Säckingen, Germany).

Methods

The ceramic blocks were polished (4000 grit) and sandblasted (SB) with airborne particle abrasion Al₂O₃; 110 μm particle size; 2.8 bar; 20 s. The following treatments were performed: (1) no treatment; (2) Rocatec System (RC): after SB treatment, sandblasting with silica powder; 30 μm particle size; 2.8 bar; 20 s. (3) Neodymium:yttrium–aluminium–garnet (Nd:YAG) laser (ND) application of graphite powder (stain) on the ceramic surface and Nd:YAG laser irradiation (distance: 1 mm, 100 mJ, 20 Hz, 2 W, and 141.54 J/cm²). (4) Nd:YAG laser plus Rocatec System: after ND treatments, RC was applied. Digital images (20 μm × 20 μm) from the surfaces were obtained by means of an AFM microscope in taping mode (Nanoscope IIIa, Digital Instruments). Roughness was measured in 10 μm × 10 μm boxes. Roughness (R_a) data (nm) were analyzed by one-way ANOVA (p < 0.05).

Results

No differences in ceramic surfaces roughness occurred after any of the tested treatments (p = 0.54).

Conclusions

High-alumina ceramic surface roughness was not increased with any of the tested treatments.     

Interface of dentine to root canal sealers

Objective

Root canal sealers can interact physically or chemically with dentine. The aim of this study was to characterize the dentine-root canal sealer interface of experimental sealers based on Portland cement using an epoxy-based vehicle in comparison to an epoxy resin sealer, AH Plus.

Methods

Root canals were biomechanically prepared and filled with any one of the four experimental epoxy sealers containing Portland cement with micro- and nano-particles of either zirconium oxide or niobium oxide radiopacifers, or AH Plus. The dentine-sealer's interfaces were assessed by coronal penetration of fluorescent microspheres, the penetration of sealers labelled with Rhodamine B inside the dentine tubules (following obturation with gutta–percha and sealers using System B technique) assessed by confocal laser scanning microscopy, and the chemical characterization of dentine-sealers interface by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) line scans.

Results

No penetration of fluorescent microspheres at the root-dentine to sealer interface was recorded for all test materials. Sealers presented greater ability to penetrate within the dentinal tubules at the coronal and mid-root thirds. The experimental sealers containing radiopacifier nano-particles exhibited a more homogeneous microstructure along the whole length of the canal. EDS-line scans results showed a migration of silicon and niobium into dentine. Peak overlap between zirconium and the phosphorous compromised the identification of the migration of the zirconium oxide into dentine.

Conclusions

All five sealers promoted coronal sealing. The experimental sealers exhibited promising characteristics and were comparable to AH Plus sealer. Elemental migration of the experimental sealers suggests material interaction with dentine which was not displayed by AH Plus.     

A minimally destructive technique for removing the smear layer from dentine surfaces

Objectives

To develop a minimally destructive technique for removing the smear layer produced by cutting and polishing specimens of dentine prepared for use in experimental studies, e.g. on occlusion of dentinal tubules by oral health products. The aim was to avoid the damage caused by conventional techniques utilising short exposures to solutions with very low pH.

Methods

Two acetate buffers, pH 5.5, containing different concentrations of calcium and phosphate, with −log(ion activity product with respect to hydroxyapatite) (pI_HA) of 55 or 56, were tested on slices of dentine using scanning electron microscopy (SEM).

Results

A solution which, from previous work, was slightly undersaturated with respect to dentine mineral, with a pI_HA of 56, was found to remove smear layers produced by cutting and/or polishing after 15 min. However, to reliably remove debris occluding the tubules an exposure time of 2 h, followed by brief ultrasonication, was necessary. After 2 h treatment with this buffer, only a small amount of demineralization of the surface was detectable by SEM, while calcium and phosphorus were detectable by X-ray dispersive spectroscopy.

Conclusion

It is possible to remove smear layers, and to open dentinal tubules, by a reasonably short exposure to an acidic buffer which is undersaturated with respect to dentine mineral.     

Radiation therapy alters microhardness and microstructure of enamel and dentin of permanent human teeth

Objectives

To evaluate, in vitro, the effects of ionizing radiation on the mechanical and micro-morphological properties of enamel and dentin of permanent teeth.

Methods

Enamel and dentin microhardness (n = 12 hemi-sections) was evaluated at three depths (superficial, middle and deep) prior to (control) and after every 10 Gy radiation dose up to a cumulative dose of 60 Gy by means of longitudinal microhardness. Data were analyzed using two-way analysis of variance and Tukey's test at a significance level of 5%. Enamel and dentin morphology was assessed by scanning electron microscopy (SEM) for semi-quantitative analysis (n = 8 hemi-sections). Data were analyzed using Kruskal–Wallis and Dunn's or Fisher exact tests at a significance level of 5%.

Results

The application of ionizing radiation did not change the overall enamel microhardness, although an increase in superficial enamel microhardness was observed. The micro-morphological analysis of enamel revealed that irradiation did not influence rod structure but interprismatic structure became more evident. Dentin microhardness decreased after 10, 20, 30, 50 and 60 Gy cumulative doses (p < 0.05) compared with non-irradiated dentin, mainly in the middle portion of the tissue. The micro-morphological analysis revealed fissures in the dentin structure, obliterated dentinal tubules and fragmentation of collagen fibers after 30 and 60 Gy cumulative doses.

Conclusions

Although ionizing radiation did not affect the enamel microhardness of permanent teeth as a whole, an increase in superficial enamel microhardness was observed. Dentin microhardness decreased after almost all radiation doses compared with the control, with the greatest reduction of microhardness in the middle depth region. The morphological alterations on enamel and dentin structures increased with the increase of the radiation dose, with a more evident interprismatic portion, presence of fissures and obliterated dentinal tubules, and progressive fragmentation of the collagen fibers.

Clinical significance

This study shows that irradiation affects microhardness and micro-morphology of enamel and dentin of permanent teeth. The effects of gamma irradiation on dental substrate might contribute to increased risk of radiation tooth decay associated with salivary changes, microbiota shift and high soft and carbohydrate-rich food intake.     

Antimicrobial Activity of a Sodium Hypochlorite/Etidronic Acid Irrigant Solution

Introduction

The aim of this study was to evaluate the antimicrobial activity of a 2.5% sodium hypochlorite (NaOCl)/9% etidronic acid (HEBP) irrigant solution on Enterococcus faecalis growing in biofilms and a dentinal tubule infection model.

Methods

The antimicrobial activity of the solutions 2.5% NaOCl and 9% HEBP alone and associated was evaluated on E. faecalis biofilms grown in the Calgary biofilm model (minimum biofilm eradication concentration high-throughput device). For the dentinal tubule infection test, the percentage of dead cells in E. faecalis–infected dentinal tubules treated with the solutions for 10 minutes was measured using confocal laser scanning microscopy and the live/dead technique. Available chlorine and pH of the solutions were also measured. Distilled water was used as the control. Nonparametric tests were used to determine statistical differences.

Results

The highest viability was found in the distilled water group and the lowest in the NaOCl-treated dentin (P < .05). Both NaOCl solutions killed 100% of the E. faecalis biofilms and showed the highest antimicrobial activity inside dentinal tubules, without statistical differences between the 2 (P < .05). The HEBP isolated solution killed bacteria inside dentinal tubules but did not present any significant effect against E. faecalis biofilms. The incorporation of HEBP to NaOCl did not cause any loss of available chlorine within 60 minutes.

Conclusions

HEBP did not interfere with the ability of NaOCl to kill E. faecalis grown in biofilms and inside dentinal tubules.     

Effect of 1440-Nanometer Neodymium:Yttrium-Aluminum-Garnet Laser Irradiation on Pain and Neuropeptide Reduction: A Randomized Prospective Clinical Trial

Introduction

The purpose of this study was to investigate the efficacy of a 1440-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser on relieving pain in relation to the levels of inflammatory cytokine and neuropeptides in the root canal exudates of teeth with persistent symptomatic apical periodontitis.

Methods

Forty teeth with persistent symptomatic apical periodontitis were randomly assigned to treatment groups: group L, intracanal irradiation of 1440-nm Nd:YAG laser with a 300-μm-diameter fiberoptic tip in addition to conventional root canal retreatment, and group C, conventional root canal re-treatment. The degrees of both spontaneous pain and the pain on percussion before and after treatment were recorded, and root canal exudate samples were collected to quantify the associated levels of substance P, calcitonin gene-related peptide (CGRP), and matrix metalloproteinase (MMP)-8 by immunoassay.

Results

All of the measured parameters were significantly reduced in group L (P < .05), whereas the level of pain on percussion, CGRP, and MMP-8 were significantly reduced in group C (P < .05). The 1440-nm Nd:YAG laser had significantly better effect on the relief of pain on percussion and the reduction of substance P, CGRP, and MMP-8 levels. The visual analog scale scores of perceived pain correlated with pain-related neuropeptides and inflammatory cytokine levels in root canal exudates.

Conclusions

The 1440-nm Nd:YAG laser irradiation via fiberoptic tip to the teeth with persistent apical periodontitis provided promising consequences of pain and inflammation modulation.     

Influence of Drying Protocol with Isopropyl Alcohol on the Bond Strength of Resin-based Sealers to the Root Dentin

Introduction

This study compared the bond strength, interfacial ultrastructure, and tag penetration of resin-based sealers applied to smear-free radicular dentin using 70% isopropyl alcohol as the active final rinse.

Methods

Eighty root canals were prepared and assigned to 2 groups (n = 40) according to the drying protocol: paper points or 70% isopropyl alcohol. Then, roots were divided into 4 subgroups (n = 10) with respect to the sealer and obturation material: AH Plus (Dentsply De Trey GmbH, Konstanz, Germany) and gutta-percha (AH/GP), Hybrid Root SEAL (Sun Medical, Tokyo, Japan) and gutta-percha (HR/GP), Epiphany SE (Pentron Clinical Technologies, Wallingford, CT) and gutta-percha (EP/GP), and Epiphany SE and Resilon (EP/RS). Roots were sectioned, and the push-out test was performed. Failure modes were examined under stereomicroscopy and sealer penetration into the dentinal tubules under scanning electron microscopy. Data were statistically analyzed by 2-way analysis of variance post hoc Tukey tests with a significant level of 5%.

Results

Overall, canals dried with isopropyl alcohol showed significantly higher bond strength values (2.11 ± 1.74 MPa) than with paper points (1.81 ± 1.73 MPa) (P < .05). The HR/GP group showed lower bond strength than the AH/GP group (P < .05) but higher than the EP/GP and EP/RS groups (P < .05). The most frequent type of failure was cohesive in the AH/GP and HR/GP groups and adhesive in the EP/GP and EP/RS groups. Scanning electron microscopic evaluation revealed better adaptation of the adhesive interface in the AH/GP and HR/GP groups in comparison with the EP/GP and EP/RS groups.

Conclusions

A final rinse with EDTA and 70% isopropyl alcohol improved the bond strength and penetration of the sealers into dentinal tubules of the root.     

Influence of the irradiation distance and the use of cooling to increase enamel-acid resistance with Er:YAG laser

Objectives

The aim of this study was to assess the influence of irradiation distance and the use of cooling in the Er:YAG laser efficacy in preventing enamel demineralization.

Methods

84 enamel blocks were randomly assigned to seven groups (n = 12): G1: control group – no treatment, G2–G7: experimental groups treated with Er:YAG laser (80 mJ/2 Hz) at different irradiation distances with or without cooling: G2: 4 mm/2 mL; G3: 4 mm/no cooling; G4: 8 mm/2 mL; G5: 8 mm/no cooling; G6: 16 mm/2 mL; G7: 16 mm/no cooling. The samples were submitted to an in vitro pH cycles for 14 days. Next, the specimens were sectioned in sections of 80–100 μm in thickness and the demineralization patterns of prepared slices were assessed using a polarized light microscope. Three samples from each group were analyzed with scanning electronic microscopy. Analysis of variance and the Fisher test were performed for the statistical analysis of the data obtained from the caries-lesion-depth measurements (CLDM) (alpha = 5%).

Results

The control group (CLDM = 0.67 mm) was statistically different from group 2 (CLDM = 0.42 mm), which presented a smaller lesion depth, and group 6 (0.91 mm), which presented a greater lesion depth. The results of groups 3 (CLDM = 0.74 mm), 4 (CLDM = 0.70 mm), 5 (CLDM = 0.67 mm) and 7 (CLDM = 0.89 mm) presented statistical similarity. The scanning electronic microscopy analysis showed ablation areas in the samples from groups 4, 5, 6 and 7, and a slightly demineralized area in group 2.

Conclusions

It was possible to conclude that Er:YAG laser was efficient in preventing enamel demineralization at a 4-mm irradiation distance using cooling.     

A photochemical method for in vitro evaluation of fluid flow in human dentine

Objective

To evaluate the flow dynamics of dentine fluid using a chemiluminescence method in vitro.

Materials and methods

Horizontally sliced coronal dentine specimens with thicknesses of 1.4, 1.6, 1.8, and 2.0 mm (n = 10 each) were prepared from extracted human third molars. After cleaning with EDTA, a mounted specimen was clamped between 2 acrylic chambers attached to both the occlusal and pulpal sides. The occlusal chamber, which was closed with a glass coverslip, was filled with a chemiluminescent solution (0.02% luminol and 1% sodium hydroxide in water). A trigger solution of 1% hydrogen peroxide and 1% potassium ferricyanide was injected into the pulpal chamber at a constant pressure of 2.5 kPa, and allowed to immediately flow into the patent dentinal tubules. Four consecutive measurements (T1–T4) were performed on each sample by recording the emission of chemiluminescence with a photodetector. The relationship between the crossing time of the liquid through the slice and dentine thickness was examined.

Results

An apparent time delay was detected between the starting points of the trigger solution run and photochemical emission at T1. Dt (Dt, s) values of each thickness group were 13.6 ± 4.25 for 1.4 mm, 18.1 ± 2.38 for 1.6 mm, 28.0 ± 2.46 for 1.8 mm, and 39.2 ± 8.61 for 2.0 mm, respectively. Dt significantly decreased as dentine became thinner towards the pulp chamber (P < 0.001).

Conclusions

The velocity of fluid flow increased both with increasing dentine depth or reduction of remaining dentine thickness.     

The inhibition effect of non-protein thiols on dentinal matrix metalloproteinase activity and HEMA cytotoxicity

Objectives

Phosphoric acid (PA) etching used in etch-and-rinse adhesives is known to activate host-derived dentinal matrix-metalloproteinases (MMPs) and increase dentinal permeability. These two phenomena will result, respectively; in degradation of dentine-adhesive bond and leaching of some monomers especially 2-hydroxyethyl methacrylate (HEMA) into the pulp that would negatively affect the viability of pulpal cells. This study is the first to investigate the inhibitory effect of non-protein thiols (NPSH); namely reduced glutathione (GSH) and N-acetylcysteine (NAC) on dentinal MMPs and compare their effects on HEMA cytotoxicity.

Methods

Dentine powder was prepared from human teeth, demineralized with 1% PA and then treated with 2% GSH, 2% NAC or 2% chlorhexidine (CHX). Zymographic analysis of extracted proteins was performed. To evaluate the effect of GSH, NAC and CHX on HEMA cytotoxicity, solutions of these compounds were prepared with or without HEMA and rat pulpal cells were treated with the tested solutions for (6 and 24 h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxicity data were analysed by one-way ANOVA and Tukey post hoc tests (p < 0.05).

Results

The inhibitory effect of GSH and NAC on dentinal MMPs was confirmed. GSH showed similar effectiveness to NAC regarding HEMA cytotoxicity inhibition.

Conclusion

NPSH were effective to inhibit dentinal MMPs and HEMA cytotoxicity.

Clinical significance

The tested properties of NPSH provide promising clinical use of these agents which would enhance dentine-bond durability and decrease post-operative sensitivity.     

Dentine desensitization induced by prophylactic and air-polishing procedures: An in vitro dentine permeability and confocal microscopy study

Objectives

The exposure of dentinal tubules causes fluid movement and dentinal hypersensitivity. This study aimed at evaluating the dentine permeability after prophylactic measures performed on exposed dentine after immersion in artificial saliva and citric acid challenge. Confocal microscopy was performed to evaluate the percentage of occluded tubules (OCT%) and the changes in dentine morphology.

Methods

Prophy-powders and pastes were tested in this study. An oxalic acid liner was used as a positive control. Dentine discs from human third molars were treated with each material and the dentine permeability was evaluated using a fluid filtration system working at 20 cm H₂O. Artificial saliva and citric acid were used for the determination of changes in dentine permeability. The percentage of tubule occlusion capability (OCT%) was evaluated using confocal microscopy.

Results

All the products used in this study were able to significantly reduce the dentine permeability of acid-etched specimens. The use of the bioactive glass and sodium bicarbonate showed the highest values in dentine permeability reduction. However, the air-polishing procedures performed with Sylc bioactive glass powder created a dentine surface resistant to citric acid attack.

Conclusion

Bioactive glass is suitable for treatment of dentinal hypersensitivity by creating a dentine surface resistant to citric acid attack.     

Effect of Calcium Hydroxide Dressing on the Dentinal Tubule Penetration of 2 Different Root Canal Sealers: A Confocal Laser Scanning Microscopic Study

Introduction

The purpose of this study was to evaluate the effect of calcium hydroxide (Ca[OH]₂) dressing on the dentinal tubule penetration of epoxy resin–based sealer (AH 26; Dentsply Maillefer, Ballaigues, Switzerland) and tricalcium silicate–based sealer (BioRoot RCS; Septodont, Saint Maurdes Fosses, France).

The effect of custom adaptation and span-diameter ratio on the flexural properties of fiber-reinforced composite posts

Objectives

To evaluate whether custom modification resulting in an anatomically shaped post and whether the span/diameter ratio (L/D) would affect the mechanical properties of fiber-reinforced composite posts.

Methods

Preformed glass-fiber posts (Group 1) and modified glass-fiber posts (Group 2) and glass-fiber rods (Groups 3 and 4) (n = 20) were loaded to failure in a three-point bending test to determine the maximum load (N), flexural strength (MPa) and flexural modulus (GPa). The span distance tested for Group 3 was 10.0 mm, while for Group 4 was 22.0 mm. Data were subjected to different statistical analysis with significance levels of P < 0.05.

Results

The maximum load recorded for Groups 1 and 2 was 72.5 ± 5.9 N and 73.4 ± 6.4 N respectively, while for Groups 3 and 4 was 215.3 ± 7 N and 156.6 ± 3.6 N respectively. The flexural strength for Groups 1 and 2 was 914.6 ± 53.1 MPa and 1069.2 ± 115.6 MPa, while for Groups 3 and 4 was 685.4 ± 22.2 MPa and 899.6 ± 46.1 MPa. The flexural modulus recorded for Groups 1 and 2 was 32.6 ± 3.2 GPa and 33.4 ± 2.2 GPa respectively, while for Groups 3 and 4 was 13.7 ± 0.3 GPa and 34.4 ± 0.3 GPa respectively.

Conclusions

The flexural properties of an anatomically custom modified fiber post were not affected by the modification procedure and the span-diameter ratio is an important parameter for the interpretation of flexural strength and flexural modulus values.     

Chemical–physical properties of experimental root canal sealers based on butyl ethylene glycol disalicylate and MTA

Objective

The aim of this study was to evaluate the calcium release, pH, flow, solubility, water absorption, setting and working time of three experimental root canal sealers based on mineral trioxide aggregate (MTA) and two forms of calcium phosphates (CaP).

Methods

The materials were composed of a base and a catalyst pastes mixed in a 1:1. The base paste was made by 60% bismuth oxide and 40% butyl ethylene glycol disalicylate. Three different catalyst pastes were formulated containing 60% MTA or 40% MTA + 20% CaP (hydroxyapatite HA or dibasic calcium phosphate dehydrate DCPD), 39% Resimpol 8% and 1% titanium dioxide. MTA Fillapex was used as control. The release of calcium and hydroxyl ions, solubility and water absorption were measured on regular intervals for 28 days. The working time and flow were tested according to ISO 6876:2001 and the setting time according to ASTM C266. The data were analyzed using 1-way ANOVA with Tukey's test (p < .01).

Results

All the cements showed basifying activity and released calcium ions. MTA Fillapex showed the highest values of flow (p < .01) and working/setting times (p < .01) and the smallest values of solubility (p < .01) and water absorption (p < .01).

Significance

All experimental materials showed satisfactory physical–chemical properties to be used as endodontic sealers in clinical practice.