In vitro evaluation of dentinal tubule penetration and biomineralization ability of a new root-end filling material

A novel simplified approach for endodontic retrograde surgery in short single-rooted teeth

BACKGROUND

High technical thresholds, long operative times, and the need for expensive and specialized equipment impede the widespread adoption of endodontic microsurgery in many developing countries. This study aimed to compare the effects of a simplified, cost-effective, and time-efficient surgical approach involving orthograde obturation using biological ceramic material greater than 6 mm combined with apicoectomy for single-rooted teeth with short lengths with those of the conventional and current standard methods.

MATERIALS AND METHODS

Forty-five premolars equally categorized into three groups: conventional surgery group, standard surgery group, and modified surgery group. A µCT scan was used to calculate the volume of voids. A micro-leakage test and scanning electron microscope (SEM) were performed to assess the sealing effect. Additionally, four cases of chronic periapical periodontitis in the anterior region were selected, and the patients received either the modified approach or the standard surgery for endodontic microsurgery.

RESULTS

The volumes of voids in the apical 0-3 mm of the modified group and the standard group were comparable. The micro-leakage test and SEM examination demonstrated closely bonded fillings in the dentinal walls in both the modified surgery group and standard surgery group. The outcomes of the preliminary application of this modified procedure on patients were successful at the time of the follow-up cutoff.

CONCLUSIONS

The modified surgery group exhibited similar root canal filling and apical sealing abilities with the standard procedure for single-rooted teeth with short lengths (< 20 mm). The preliminary application of this modified surgical procedure achieved favorable results.

The effects of chelation on the intratubular penetration depth of mineral trioxide aggregate

The penetration depth and extent of mineral trioxide aggregate (MTA) crystallisation into dentinal tubules at 2, 4 and 6 weeks after chelation and MTA obturation were investigated. Standardised 12 mm human root specimens (45) were prepared with NiTi rotary files using 4% NaOCl irrigation. They were randomly allocated to three irrigants (n = 15: 4% NaOCl, 15% ethylenediaminetetraacetic acid or Edgemix) and obturated with sodium fluorescein tagged ProRoot MTA. One millimetre thick apical, middle and coronal sections were examined using confocal laser scanning microscopy to determine MTA penetration depth and area. Depths varied from 352 to 1821 μm at 6 weeks depending on section level and were unaffected by chelation. No differences (p > 0.05) were found in mean maximum penetration depth or dentine area (%) between the 3 irrigants at all time intervals. MTA mineralisation penetrated up to 90% of dentinal tubules and can extend to the cementum in roots with patent, non-infected tubules.

Comparison of sealer penetration of sonic activation versus conventional needle irrigation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Most existing studies comparing the efficiency of sonic irrigation (SI) and conventional needle irrigation (CNI) in increasing the penetration of sealers into dentine tubules are controversial; and this study aimed to determine whether the use of SI can lead to greater sealing ability than CNI, during the root canal treatment.

METHODS

The EMBASE, PubMed, and Cochrane Library databases were used to find confocal laser scanning microscopy studies evaluating percentage and maximum depth of sealer penetration following the use of SI or CNI in mature permanent teeth until October 2022. The critical estimative checklist of randomized controlled trials of the standardized Joanna Briggs Institute was adopted to independently score the quality of each study. The random-effect model for meta-analysis was used to analyse for each canal segment (apical, middle, coronal). The results are shown in the forest plots as weighted mean differences (WMDs) with 95% confidence intervals (95% CIs).

RESULTS

Ninety-seven articles were included in the preliminary screening, and nine of them were included in this study. Eight studies were included in the meta-analysis.The meta-analysis exhibited great increases in the coronal (WMD: 8.09, 95% CI 2.78-13.40/WMD: 165.32, 95% CI 128.85-201.80), and middle segments (WMD: 8.81, 95% CI 5.76-11.87/WMD: 132.98, 95% CI 68.71-197.25) for the percentage and maximum depth of sealer penetration, respectively. The percentage of sealer penetration in the apical thirds region was nonsignificant (WMD: 4.73, 95% CI - 2.34-11.80). However, the maximum depth of sealer penetration in the apical thirds region was significant (WMD: 121.46, 95% CI 86.55-156.38). Chi-squared analysis revealed heterogeneity scores of 0.0-70.0% and 44.0-90.0% for the percentage and maximum depth of sealer penetration, respectively.

DISCUSSION

This review verified that SI significantly improves tubular dentin sealer penetration in most areas of the root canal; thus, SI may lead to better filling efficiency and anti-reinfection effects than CNI during and after the root canal therapy. Nevertheless, a large heterogeneity in the current data comparing the irrigation efficiency of SI versus CNI in the apical third of the root canal was found, implying the necessity to standardize root canal irrigation procedures and obtain more accurate results in this area.

TRIAL REGISTRATION

INPLASY database (INPLASY202270116).

Push-Out Bond Strength of Calcium Silicate-Based Cements in the Presence or Absence of a Smear Layer

Objectives. Variations between the material compositions and the presence of a smear layer on the dentin surface may influence the bond strength of the material, thus this study evaluated the push-out bond strength of different calcium silicate materials to root dentin in the presence or absence of smear layer. Materials and Methods. The palatal canal of sixty maxillary first premolars were prepared and divided into three groups according to the materials to be used: ProRoot WMTA, Biodentine, and TotalFill FS. Each group was then divided into two subgroups; with and without a smear layer. Roots were sectioned into three slices and filled with the tested materials. Push-out bond strength of materials was measured by universal machine. Results. Bond strength of Biodentine was significantly higher than the MTA and TotalFill FS in the presence or absence of smear layer. Overall, removing the smear layer reduced the bond strength of the three materials. The reduction was significant for MTA and TotalFill FS but not for Biodentine. Conclusions. Biodentine demonstrated the highest bond strength to radicular dentin followed by MTA, and then TotalFill FS. Overall, removal of the smear layer from dentin surface reduced the bond strength of the calcium silicate root repair materials.

Present Status and Future Directions - Surgical Endodontics

Endodontic surgery encompasses several procedures for the treatment of teeth with a history of failed root canal treatment, such as root-end surgery, crown- and root resections, surgical perforation repair, and intentional replantation. Endodontic microsurgery is the evolution of the traditional apicoectomy techniques and incorporates high magnification, ultrasonic root-end preparation and root-end filling with biocompatible filling materials. Modern endodontic surgery uses the dental operating microscope, incorporates cone-beam computed tomography (CBCT) for preoperative diagnosis and treatment planning, and has adopted piezoelectric approaches to osteotomy and root manipulation. Crown- and root resection techniques have benefitted from the same technological advances. This review focuses on the current state of root-end surgery by comparing the techniques and materials applied during endodontic microsurgery to the most widely used earlier methods and materials. The most recent additions to the clinical protocol and technical improvements are discussed, and an outlook on future directions is given. While non-surgical retreatment remains the first choice to address most cases with a history of endodontic failure, modern endodontic microsurgery has become a predictable and minimally invasive alternative for the retention of natural teeth.

Effect of apexification on occlusal resistance of immature teeth

Background

Strain distribution was investigated to assess the occlusal resistance alterations in immature teeth under different occlusal force.

Methods

In vitro apexification models of teeth with a funnel-shaped immature apex were obturated with mineral trioxide aggregate (MTA; ProRoot MTA) using different combinations of core materials (10/group): group 1, full-length orthograde obturation of MTA; group 2, a 5-mm MTA apical plug with a composite core; group 3, a 5-mm MTA apical plug and back-filling with warm gutta-percha. Teeth with calcium hydroxide (CH)-medicated canals and untreated teeth with normal apices were tested as controls. The teeth were arranged between two adjacent normal-apex teeth, embedded in a resin mold with a simulated periodontal ligament space. Strain data were recorded from the 3-unit teeth assembly under static compressive occlusal forces (50, 100, 200, and 300 N). Measurements were repeated 20 times for each condition, and the data were statistically analyzed.

Results

The immature teeth showed altered occlusal force resistance, placing increased strain on adjacent teeth. Teeth with CH-medicated canals showed significantly inferior occlusal resistance under all tested forces (P < 0.05). Application of an MTA plug with deep composite resin core resulted in significantly better stress-bearing capacity especially under forces of 50 and 300 N (P < 0.05).

Conclusions

The pattern of occlusal force distribution in immature teeth differed according to the canal obturation materials used for apexification. Immature teeth with an MTA apical plug showed more favorable occlusal force resistance than those with CH-medicated canals.

Egyptian Propolis-Loaded Nanoparticles as a Root Canal Nanosealer: Sealing Ability and in vivo Biocompatibility

Background

Successful endodontic therapy is mainly governed by the satisfactory sealing ability of the applied root canal sealer. Also, tolerability of root canal structure to accommodate the presence of a sealer participates in the efficiency of the treatment. Hence, this study was aimed to extrapolate our previous one that was concerned with the preparation and evaluation of novel nature-based root canal sealers. Our current work is focused on the evaluation of sealing ability and in vivo biocompatibility.

Materials and Methods

Egyptian propolis was extracted (ProE) and encapsulated in polymeric nanoparticles (ProE-loaded NPs). Two root sealers, PE sealer and PE nanosealer, were fabricated by incorporating ProE and ProE-loaded NPs, respectively. The sealing ability of the developed sealers was tested by a dye extraction method. An in vivo biocompatibility study was conducted using a subcutaneous implantation method for two and four weeks. At the same time, a model sealer (AH Plus®) was subjected to the same procedures to enable accurate and equitable results.

Results

The teeth treated with PE sealer exhibited weak sealing ability which did not differ from that of unfilled teeth. PE nanosealer enhanced the sealing ability similarly to the model sealer with minimal apical microleakage. Studying in vivo biocompatibility indicated the capability of the three tested sealers to induce cell proliferation and tissue healing. However, PE nanosealer had superior biocompatibility, with higher potential for cell regeneration and tissue proliferation.

Conclusion

PE nanosealer can be presented as an innovative root canal sealer, with enhanced sealing ability as well as in vivo biocompatibility. It can be applied as a substitute for the currently available sealers that demonstrate hazardous effects.

Pre-application of dentin bonding agent prevents discoloration caused by mineral trioxide aggregate

BACKGROUND

To evaluate tooth discoloration by newly developed calcium silicate-based materials, and to examine the pre-application of dentin bonding agent (DBA) for preventing discoloration caused by mineral trioxide aggregate (MTA).

METHODS

The roots of 50 premolars were randomly divided into five groups (n = 10) and cavities were prepared from resected root surfaces. MTA was placed in the cavities of teeth belonging to the ProRoot MTA (MTA) and RetroMTA (RMTA) groups. For teeth belonging to the ProRoot + DBA (MTA-B) and RetroMTA + DBA (RMTA-B) groups, DBA was first applied to the cavities prior to the addition of MTA. Teeth in the control group were restored with composite resin only (i.e., without MTA). After 12 weeks, MTA was removed from the MTA and RMTA groups and bleaching agents were applied for 3 additional weeks. Color assessments were recorded at baseline, and 1, 4, and 12 weeks, as well as after bleaching. A one-way ANOVA was performed to assess the differences between the two types of MTAs and color changes following DBA pre-application in each MTA group. A p-value of < 0.05 was considered indicative of statistical significance.

RESULTS

Following 12 weeks of MTA treatment, there was a significant difference between the discoloration in the MTA and RMTA groups (p < 0.05). However, no significant difference was observed between the RMTA and RMTA-B groups (p > 0.05). Following bleaching, the color changes (ΔE values) of the MTA group were not significantly different from those of the MTA-B group (p > 0.05). The difference of ΔE between the RMTA group after internal bleaching and the RMTA-B group was also not significant (p > 0.05).

CONCLUSIONS

RetroMTA caused significantly less discoloration than ProRoot MTA. Pre-application of DBA reduced discoloration caused by ProRoot MTA. MTA discoloration was improved equally well between DBA pre-application and post-bleaching.

Bioactive tri/dicalcium silicate cements for treatment of pulpal and periapical tissues

Over 2500 articles and 200 reviews have been published on the bioactive tri/dicalcium silicate dental materials. The indications have expanded since their introduction in the 1990s from endodontic restorative and pulpal treatments to endodontic sealing and obturation. Bioactive ceramics, based on tri/dicalcium silicate cements, are now an indispensable part of the contemporary dental armamentarium for specialists including endodontists, pediatric dentists, oral surgeons andfor general dentists. This review emphasizes research on how these materials have conformed to international standards for dental materials ranging from biocompatibility (ISO 7405) to conformance as root canal sealers (ISO 6876). Potential future developments of alternative hydraulic materials were included. This review provides accurate materials science information on these important materials. STATEMENT OF SIGNIFICANCE: The broadening indications and the proliferation of tri/dicalcium silicate-based products make this relatively new dental material important for all dentists and biomaterials scientists. Presenting the variations in compositions, properties, indications and clinical performance enable clinicians to choose the material most suitable for their cases. Researchers may expand their bioactive investigations to further validate and improve materials and outcomes.

Effect of ultrasonic activation on dentinal tubule penetration of calcium silicate-based cements

This study investigated the dentinal tubule penetration of mineral trioxide aggregate (MTA), NeoMTA Plus and Biodentine placed by either manual condensation or ultrasonic activation in simulated open apex model. Standardized divergent open apex models were created using palatal roots of 60 human maxillary molars and divided into six groups according to the used cements and activation methods (n = 10): MTA-manual condensation, MTA-ultrasonic activation, NeoMTA Plus-manual condensation, NeoMTA Plus-ultrasonic activation, Biodentine-manual condensation, Biodentine-ultrasonic activation. For the measurement of penetration, the cements were mixed with 0.1% Rhodamin B and 6-mm apical portions of each root canal were obturated in an orthograde direction. The roots were embedded into acrylic blocks, and 1-mm-thick sections were obtained at 3 mm from the apex. Specimens were mounted onto glass slides and scanned under a confocal laser scanning microscope (CLSM) and stereomicroscope. Dentinal tubule penetration areas, depth and percentage were measured using LSM and ImageJ software. The data were analyzed using two-way analysis of variance (anova) with Bonferroni correction (α = 0.05). No correlation was found between stereomicroscope and CLSM analyses (p > .05). CLSM analysis showed no significant differences between MTA, NeoMTA Plus, and Biodentine groups when manual condensation was used (p > .05). Ultrasonic activation did not increase the tubular penetration of MTA, NeoMTA Plus or Biodentine as compared to manual condensation of each material (p > .05). MTA, NeoMTA Plus and Biodentine showed similar tubular penetration when manual condensation was used. Ultrasonic activation of these cements had no effect on tubular penetration of each material as compared to the manual condensation counterparts.

Histology of NeoMTA Plus and Quick-Set2 in Contact with Pulp and Periradicular Tissues in a Canine Model

INTRODUCTION

NeoMTA Plus (Avalon Biomed Inc, Bradenton, FL) is a tricalcium silicate material similar to the first mineral trioxide aggregate product, ProRoot MTA (Dentsply Sirona, York, PA), but with improvements such as decreased setting time, increased ion release, increased water sorption, and nonstaining radiopacifiers. Quick-Set2 (Avalon Biomed Inc) is a newly formulated calcium aluminosilicate material that has a faster setting time and increased acid resistance and is nonstaining. The purpose of this study was to compare the healing of pulpal and periapical tissues in dogs after exposure to NeoMTA Plus and Quick-Set2 after pulpotomy and root-end surgery procedures.

METHODS

Seventy-two teeth (36 for each procedure) in 6 beagle dogs received pulpotomy or root-end surgery using either NeoMTA Plus or Quick-Set2. The dogs were sacrificed at 90 days, and the teeth and surrounding tissues were prepared for histologic evaluation. Sixty teeth were evaluated and scored histologically (29 with pulpotomies and 31 with root-end resections). Specimens were scored for inflammation, quality and thickness of dentin bridging, pulp tissue response, cementum and periodontal ligament formation, and apical bone healing.

RESULTS

Both materials displayed favorable healing at 90 days. The only significant difference was the quality of dentin bridge formation in pulpotomies using NeoMTA Plus compared with Quick-Set2.

CONCLUSIONS

Quick-Set2 and NeoMTA Plus had similar effects on inflammation, pulp response, periodontal ligament and cementum formation, and apical tissue healing in dogs. NeoMTA Plus had superior dentin bridge quality compared with Quick-Set2.

Chemical Composition and Porosity Characteristics of Various Calcium Silicate-Based Endodontic Cements

Chemical composition and porosity characteristics of calcium silicate-based endodontic cements are important determinants of their clinical performance. Therefore, the aim of this study was to investigate the chemical composition and porosity characteristics of various calcium silicate-based endodontic cements: MTA-angelus, Bioaggregate, Biodentine, Micromega MTA, Ortho MTA, and ProRoot MTA. The specific surface area, pore volume, and pore diameter were measured by the porosimetry analysis of N2 adsorption/desorption isotherms. Chemical composition and powder analysis by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were also carried out on these endodontic cements. Biodentine and MTA-angelus showed the smallest pore volume and pore diameter, respectively. Specific surface area was the largest in MTA-angelus. SEM and EDS analysis showed that Bioaggregate and Biodentine contained homogenous, round and small particles, which did not contain bismuth oxide.

Effect of novel chelating agents on the push-out bond strength of calcium silicate cements to the simulated root-end cavities

To compare the effects of different chelating agents on the push-out bond strength of calcium silicate-based cements to the simulated root-end cavities. Root-end cavities were prepared on the roots of fifty extracted maxillary anterior teeth. The specimens were then randomly divided into 5 groups (n = 10) based on the final irrigation regimen: Group 1: 17% EDTA, Group 2: 7% maleic acid, Group 3: QMix, Group 4: 2.25% peracetic acid (PAA), Group 5: 0.9% saline. Then, the samples from each group were subdivided into two groups (n = 5) based on the apical filling material. In group 1, root-end cavities of all samples were filled with Biodentine and in group 2, with MTA. Each sample was horizontally sectioned to produce two discs of ∼1 mm thick per specimen. The maximum load required for the dislodgement of 100 retrofillings was recorded. The specimens were examined under scanning electron microscope after debonding to assess the type of bond failure. Data were statistically analyzed using Kruskal Wallis and Mann Whitney U tests. Irrigation with saline resulted in higher bond strength compared to the other irrigants in the retrograde cavities obturated with MTA or Biodentine (p < .05). In MTA group, there was no significant difference between the test irrigants (p > .05). EDTA and PAA groups showed higher dislodgement resistance values than the other test irrigants, when Biodentine was used as a filling. The type of irrigation solution influences the bond strength of the root-end fillings.

Sealer penetration and adaptation in root canals with the butterfly effect

The butterfly effect is a phenomenon seen in some roots and is related to density of dentinal tubules. The aim was to investigate penetration depth and adaptation quality of root canal sealers and ProRoot MTA into bucco-lingual and mesio-distal aspects of roots with and without the effect. One hundred and twenty teeth were decoronated at the cemento-enamel junction. Canals were prepared and assigned to obturation groups: gutta-percha with a sealer (AH Plus, EndoREZ, Kerr Pulp Canal Sealer, MTA Fillapex) or ProRoot MTA alone (each containing 10 butterfly and 10 non-butterfly roots). Root sectioning yielded coronal and middle samples. Confocal laser scanning and scanning electron microscopy were used to assess penetration and adaptation. Teeth with the effect had greater mean penetration bucco-lingually (766 μm) than mesio-distally (184 μm, P = 0.003). Coronal sections had greater penetration (430 μm) compared with middle (247 μm, P = 0.006). In conclusion, greater penetration in roots with the effect may improve treatment outcomes.

Comparative evaluation of Fracture Resistance of Endodontically Treated Teeth Obturated with Pozzolan-based MTA Sealer and Epoxy Resin-based Sealer: An in vitro Study

Aim

To evaluate and compare the effect of epoxy resin-based sealer and a pozzolan-based mineral trioxide aggregate (MTA) sealer on the fracture resistance of endodontically treated teeth.

Materials and methods

Thirty single-rooted mandibular premolars were decoronated to a standardized root length of 15 mm. ProTaper rotary files up to a master apical file size of F3 were used for cleaning and shaping the root canals followed by 2.5% sodium hypochlorite irrigation. The teeth were randomly divided into three groups (n = 10 each), and the obturation was completed using gutta-percha with Endoseal MTA (group I) and AH Plus (group II) as root canal sealers. Group III served as control (instrumented and unfilled). Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. The force required to fracture each specimen was recorded and the data were subjected to statistical analysis using one-way analysis of variance (ANOVA), followed by pairwise comparison using post hoc Games-Howell test (p < 0.05).

Results

The fracture resistance of groups I and II were significantly higher than those of group III. No significant difference in the fracture resistance was observed between group I (Endoseal MTA) and group II (AH Plus) groups.

Conclusion

It can be concluded that the new root canal sealer, Endoseal MTA, is able to reinforce the tooth against fracture as good as AH Plus.

Clinical significance

Endoseal MTA is a sealer for the reinforcement of endodontically treated teeth.

How to cite this article

Upadhyay ST, Purayil TP, Ginjupalli K. Comparative evaluation of Fracture Resistance of EndodonticallyTreated Teeth Obturated with Pozzolan-based MTA Sealer and Epoxy Resin-based Sealer: An in vitro Study. World J Dent 2017;8(1):37-40.

Dentinal Tubule Penetration of Tricalcium Silicate Sealers

INTRODUCTION

The treatments for which mineral trioxide aggregate (MTA)-based materials can be used in dentistry are expanding. Smaller particle size and easier handling properties have allowed the advent of tricalcium silicate sealers including EndoSequence BC Sealer (Brasseler USA, Savannah, GA), QuickSet2 (Avalon Biomed, Bradenton, FL), NeoMTA Plus (Avalon Biomed), and MTA Fillapex (Angelus, Londrina, Brazil). The objective of this study was to measure the tubule penetration with these sealers using continuous wave (CW) and single-cone (SC) obturation techniques.

METHODS

Eighty single-rooted teeth were randomly divided into 8 groups of 10 and obturated with 1 of the previously mentioned sealers mixed with trace amounts of rhodamine using either the CW or SC technique. Teeth were sectioned at 1 mm and 5 mm from the apex and examined under a confocal laser microscope. The percentage of sealer penetration and the maximum sealer penetration were measured.

RESULTS

The tricalcium silicate sealers penetrated tubules as deep as 2000 μm (2 mm). The percentage of sealer penetration was much higher 5 mm from the apex, with many specimens having 100% penetration for both SC and warm vertical techniques. MTA Fillapex, a resin-based sealer with less than 20% MTA particles, had significantly greater tubule penetration with a warm vertical technique versus the SC technique at the 1-mm level.

CONCLUSIONS

Within the limitations of this study, the CW and SC techniques produced similar tubule penetration at both the 1-mm and the 5-mm level with the tricalcium silicate sealers BC Sealer, QuickSet2, and NeoMTA Plus.

Dynamic intratubular biomineralization following root canal obturation with pozzolan-based mineral trioxide aggregate sealer cement

The application of mineral trioxide aggregates (MTA) cement during the root canal obturation is gaining concern due to its bioactive characteristic to form an apatite in dentinal tubules. In this regard, this study was to assess the biomineralization of dentinal tubules following root canal obturation by using pozzolan-based (Pz-) MTA sealer cement (EndoSeal MTA, Maruchi). Sixty curved roots (mesiobuccal, distobuccal) from human maxillary molars were instrumented and prepared for root canal obturation. The canals were obturated with gutta-percha (GP) and Pz-MTA sealer by using continuous wave of condensation technique. Canals obturated solely with ProRoot MTA (Dentsply Tulsa Dental) or Pz-MTA sealer were used for comparison. In order to evaluate the biomineralization ability under different conditions, the PBS pretreatment before the root canal obturation was performed in each additional samples. At dentin-material interfaces, the extension of intratubular biomineralization was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy. When the root canal was obturated with GP and Pz-MTA sealer, enhanced biomineralization of the dentinal tubules beyond the penetrated sealer tag was confirmed under the SEM observation (p < 0.05). Mineralized apatite structures (calcium/phosphorous ratio, 1.45-1.89) connecting its way through the dentinal tubules were detected at 350-400 μm from the tubule orifice, and the pre-crystallization seeds were also observed along the intra- and/or inter-tubular collagen fiber. Intratubular biomineralization depth was significantly enhanced in all PBS pretreated canals (p < 0.05). Pz-MTA cement can be used as a promising bioactive root canal sealer to enhance biomineralization of dentinal tubules under controlled environment.

Comparative Analysis of Root Dentin Morphology and Structure of Human Versus Bovine Primary Teeth

This study evaluated the structural and morphological differences between human and bovine primary root canals. Primary human maxillary central incisors (H) (n=9) and primary bovine incisors (B) (n=9) were selected. The roots were sectioned in the vestibular-lingual direction, planed and delimited in cervical, middle, and apical thirds. Tubule density (number of tubules per mm2) and diameter were analyzed by scanning electron microscopy (1,000 and 5,000×) using Image J 1.47 software. Data were submitted to two-way repeated measures ANOVA and Tukey tests (α=0.05). The highest tubule density was observed for B (28.527±1.717 mm2) compared with H (15.931±0.170 mm2) (p<0.01). Regarding root thirds, the cervical third presented a greater tubule density (26.417±11.654 mm2) than the apical third (17.999±5.873 mm2). The diameter of the dentin tubules was not different for cervical (3.50±0.08 µm), middle (3.45±0.30 µm) and apical thirds (3.42±0.33 µm) and substrate (H-3.29±0.14 µm; B-3.63±0.06 µm). It could be concluded that: (1) the radicular dentin structure of human and bovine primary teeth and root thirds differ in terms of the tubule density; (2) the radicular dentin morphology of human and bovine primary teeth and root thirds are similar in terms of the diameter of the dentin tubules.

Clinical outcomes for teeth treated with electrospun poly(ε-caprolactone) fiber meshes/mineral trioxide aggregate direct pulp capping

INTRODUCTION

Mineral trioxide aggregate (MTA) is a biocompatible material for direct pulp capping. This study was designed to compare the clinical outcomes of pulp-exposed teeth treated with either poly(ε-caprolactone) fiber mesh (PCL-FM) as a barrier for MTA (so-called PCL-FM/MTA) or MTA direct pulp capping.

METHODS

Sixty human vital teeth were evenly divided into 4 groups (n = 15 in each group). Teeth in groups 1 and 3 had pulp exposure <1 mm in diameter, whereas teeth in groups 2 and 4 had pulp exposure of 1-1.5 mm in diameter. Teeth in groups 1 and 2 were treated with PCL-FM/MTA direct pulp capping, and those in groups 3 and 4 were treated with MTA direct pulp capping.

RESULTS

Teeth treated with PCL-FM/MTA direct pulp capping needed a significantly shorter mean duration for dentin bridge formation than teeth treated with MTA direct pulp capping. Moreover, teeth with pulp exposure <1.0 mm in diameter needed a significantly shorter mean duration for dentin bridge formation than teeth with pulp exposure of 1-1.5 mm in diameter after either PCL-FM/MTA or MTA direct pulp capping treatment. In addition, teeth treated with PCL-FM/MTA direct pulp capping formed an approximately 3-fold thicker dentin bridge than teeth treated with MTA direct pulp capping 8 weeks or 3 months later. Furthermore, none of the teeth treated with PCL-FM/MTA direct pulp capping showed tooth discoloration after treatment for 3 months.

CONCLUSIONS

PCL-FM/MTA is a better combination material than MTA alone for direct pulp capping of human permanent teeth.

A review of the bioactivity of hydraulic calcium silicate cements

OBJECTIVES

In tissue regeneration research, the term "bioactivity" was initially used to describe the resistance to removal of a biomaterial from host tissues after intraosseous implantation. Hydraulic calcium silicate cements (HCSCs) are putatively accepted as bioactive materials, as exemplified by the increasing number of publications reporting that these cements produce an apatite-rich surface layer after they contact simulated body fluids.

METHODS

In this review, the same definitions employed for establishing in vitro and in vivo bioactivity in glass-ceramics, and the proposed mechanisms involved in these phenomena are used as blueprints for investigating whether HCSCs are bioactive.

RESULTS

The literature abounds with evidence that HCSCs exhibit in vitro bioactivity; however, there is a general lack of stringent methodologies for characterizing the calcium phosphate phases precipitated on HCSCs. Although in vivo bioactivity has been demonstrated for some HCSCs, a fibrous connective tissue layer is frequently identified along the bone-cement interface that is reminiscent of the responses observed in bioinert materials, without accompanying clarifications to account for such observations.

CONCLUSIONS

As bone-bonding is not predictably achieved, there is insufficient scientific evidence to substantiate that HCSCs are indeed bioactive. Objective appraisal criteria should be developed for more accurately defining the bioactivity profiles of HCSCs designed for clinical use.

Capping a pulpotomy with calcium aluminosilicate cement: comparison to mineral trioxide aggregates

INTRODUCTION

Calcium aluminate cements have shown little affinity for bacterial growth, low toxicity, and immunogenicity when used as a restoration material, but calcium aluminate cements have not been tested in vivo in pulpotomy procedures.

METHODS

To address this question, a calcium aluminosilicate cement (Quick-Set) was tested along with 2 mineral trioxide aggregates, ProRoot MTA and MTA Plus. These cements were used as a capping agent after pulpotomy. Control rats had no pulpotomy, or the pulpotomy was not capped. Proinflammatory cytokines interleukin (IL)-1β and IL-1α were measured, and histology was performed at 30 and 60 days after capping. The nociceptive response was determined by measuring the lengthening of the rat's meal duration.

RESULTS

and

CONCLUSIONS

IL-1β and IL-1α concentrations were reduced in the capped teeth, but no differences were observed among the 3 cements. Dentinal bridging could be detected at both 30 and 60 days with each of the 3 cements, and the pulps were still vital 60 days after capping. Meal duration significantly shortened after placement of the 3 different cements, indicating a nociceptive response, but there were no differences among the materials. Calcium aluminosilicate cement had similar properties to mineral trioxide aggregates and is a viable option for pulpotomy procedures.

Effect of endodontic cement on bone mineral density using serial dual-energy x-ray absorptiometry

INTRODUCTION

Materials with new compositions were tested in order to develop dental materials with better properties. Calcium silicate-based cements, including white mineral trioxide aggregate (WMTA), may improve osteopromotion because of their composition. Nano-modified cements may help researchers produce ideal root-end filling materials. Serial dual-energy x-ray absorptiometry measurement was used to evaluate the effects of particle size and the addition of tricalcium aluminate (C3A) to a type of mineral trioxide aggregate-based cement on bone mineral density and the surrounding tissues in the mandible of rabbits.

METHODS

Forty mature male rabbits (N = 40) were anesthetized, and a bone defect measuring 7 × 1 × 1 mm was created on the semimandible. The rabbits were divided into 2 groups, which were subdivided into 5 subgroups with 4 animals each based on the defect filled by the following: Nano-WMTA (patent application #13/211.880), WMTA (as standard), WMTA without C3A, Nano-WMTA + 2% Nano-C3A (Fujindonjnan Industrial Co, Ltd, Fujindonjnan Xiamen, China), and a control group. Twenty and forty days postoperatively, the animals were sacrificed, and the semimandibles were removed for DXA measurement.

RESULTS

The Kruskal-Wallis test followed by the Mann-Whitney U test showed significant differences between the groups at a significance level of P < .05. P values calculated by the Kruskal-Wallis test were .002 for bone mineral density at both intervals and P20 day = .004 and P40 day = .005 for bone mineral content.

CONCLUSIONS

This study showed that bone regeneration was enhanced by reducing the particle size (nano-modified) and C3A mixture. This may relate to the existence of an external supply of minerals and a larger surface area of nano-modified material, which may lead to faster release rate of Ca(2+), inducing bone formation. Adding Nano-C3A to Nano-WMTA may improve bone regeneration properties.

Tooth discoloration after the use of new pozzolan cement (Endocem) and mineral trioxide aggregate and the effects of internal bleaching

INTRODUCTION

The aim of this study was to evaluate tooth discoloration after the use of mineral trioxide aggregate (MTA) and to examine the effect of internal bleaching on discoloration associated with MTA.

METHODS

Thirty-two teeth were endodontically treated. Three-millimeter plugs of MTA, ProRoot, Angelus, or Endocem were placed on the access cavities of 24 teeth. Eight teeth served as the control group. After 24 hours, the access cavities were restored, and the tooth color was recorded at baseline and at 1, 2, 4, 8, and 12 weeks. After 12 weeks, the MTA materials were removed under a microscope, and an internal bleaching treatment was performed. After removal of the MTA materials and after a 1-week bleaching treatment, the color changes were measured, and the MTA-dentin interfaces were observed under a microscope.

RESULTS

The ProRoot and Angelus groups displayed increasing discoloration during a period of 12 weeks. The discoloration associated with ProRoot and Angelus was observed at the MTA-dentin interface and on the interior surface of the dentin. However, the Endocem groups demonstrated no significant discoloration (P < .05). No marginal discoloration was observed around the material in the Endocem group. Removal of the discolored MTA was effective for resolving the discoloration in all of the experimental groups (P < .05). However, a subsequent internal bleaching treatment was not significantly effective compared with the removal of MTA.

CONCLUSIONS

ProRoot and Angelus caused tooth discoloration. However, Endocem did not affect the contacting dentin surface. Removing the discolored MTA materials contributed more to resolving the tooth discoloration than post-treatment internal bleaching.

In vitro fracture resistance of roots obturated with epoxy resin-based, mineral trioxide aggregate-based, and bioceramic root canal sealers

INTRODUCTION

The aim of this study was to evaluate the fracture resistance of teeth filled with 3 different endodontic sealers.

METHODS

Seventy-five single-rooted extracted mandibular premolars were decoronated to a length of 13 mm. The teeth were randomly divided into 5 groups (n = 15 for each group). In group 1, the teeth were left unprepared and unfilled (negative control), and in group 2, the teeth were left unobturated (positive control). The rest of the roots were prepared by using the ProTaper System up to a master apical file size of F3: group 3, bioceramic sealer (Endosequence BC sealer) + gutta-percha; group 4, mineral trioxide aggregate-based sealer (Tech Biosealer Endo) + gutta-percha; and group 5, epoxy resin-based sealer (AH Plus Jet) + gutta-percha. All root specimens were stored for 2 weeks at 100% humidity to allow the complete setting of the sealers. Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min(-1) until the root fractured. The force required to fracture each specimen was recorded, and the data were analyzed statistically.

RESULTS

The fracture values of groups 3 and 5 were significantly higher than those of group 4 (P < .05). There was no significant difference between groups 3 and 5 (P > .05).

CONCLUSIONS

In contrast to Tech Biosealer Endo, Endosequence BC and AH Plus Jet sealer increased the force to fracture in root-filled single-rooted premolar teeth.

Biocompatibility of root-end filling materials: recent update

The purpose of a root-end filling is to establish a seal between the root canal space and the periradicular tissues. As root-end filling materials come into contact with periradicular tissues, knowledge of the tissue response is crucial. Almost every available dental restorative material has been suggested as the root-end material of choice at a certain point in the past. This literature review on root-end filling materials will evaluate and comparatively analyse the biocompatibility and tissue response to these products, with primary focus on newly introduced materials.

In vitro osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement

INTRODUCTION

Calcium aluminosilicate cements are fast-setting, acid-resistant, bioactive cements that may be used as root-repair materials. This study examined the osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement (Quick-Set) by using a murine odontoblast-like cell model.

METHODS

Quick-Set and white ProRoot MTA (WMTA) were mixed with the proprietary gel or deionized water, allowed to set completely in 100% relative humidity, and aged in complete growth medium for 2 weeks until rendered non-cytotoxic. Similarly aged Teflon disks were used as negative control. The MDPC-23 cell line was used for evaluating changes in mRNA expressions of genes associated with osteogenic/dentinogenic differentiation and mineralization (quantitative reverse transcription polymerase chain reaction), alkaline phosphatase enzyme production, and extracellular matrix mineralization (alizarin red S staining).

RESULTS

After MDPC-23 cells were incubated with the materials in osteogenic differentiation medium for 1 week, both cements showed up-regulation in ALP and DSPP expression. Fold increases in these 2 genes were not significantly different between Quick-Set and WMTA. Both cements showed no statistically significant up-regulation/down-regulation in RUNX2, OCN, BSP, and DMP1 gene expression compared with Teflon. Alkaline phosphatase activity of cells cultured on Quick-Set and WMTA were not significantly different at 1 week or 2 weeks but were significantly higher (P < .05) than Teflon in both weeks. Both cements showed significantly higher calcium deposition compared with Teflon after 3 weeks of incubation in mineralizing medium (P < .001). Differences between Quick-Set and WMTA were not statistically significant.

CONCLUSIONS

The experimental calcium aluminosilicate cement exhibits similar osteogenic/dentinogenic properties to WMTA and may be a potential substitute for commercially available tricalcium silicate cements.

Chemical characteristics of mineral trioxide aggregate and its hydration reaction

Mineral trioxide aggregate (MTA) was developed in early 1990s and has been successfully used for root perforation repair, root end filling, and one-visit apexification. MTA is composed mainly of tricalcium silicate and dicalcium silicate. When MTA is hydrated, calcium silicate hydrate (CSH) and calcium hydroxide is formed. Formed calcium hydroxide interacts with the phosphate ion in body fluid and form amorphous calcium phosphate (ACP) which finally transforms into calcium deficient hydroxyapatite (CDHA). These mineral precipitate were reported to form the MTA-dentin interfacial layer which enhances the sealing ability of MTA. Clinically, the use of zinc oxide euginol (ZOE) based materials may retard the setting of MTA. Also, the use of acids or contact with excessive blood should be avoided before complete set of MTA, because these conditions could adversely affect the hydration reaction of MTA. Further studies on the chemical nature of MTA hydration reaction are needed.