Screw-in force, torque generation, and performance of glide-path files with three rotation kinetics.

We aimed to evaluate the screw-in force, torque generation, and performance of three nickel-titanium (NiTi) glide-path files with different rotational kinetics. ProTaper Ultimate Slider (PULS) and HyFlex EDM Glide-path (HEDG) files were used for canal shaping with constant rotation (CON) or the alternative rotation technique (ART). In the ART mode, the NiTi file was periodically rotated at a speed of 1.5 times faster than that in the CON mode. WaveOne Gold Glider was used with reciprocating motion (WOGG_RCP). Sixty J-shaped resin blocks were assigned to five groups: PULS_CON, PULS_ART, HEDG_CON, HEDG_ART, and WOGG_RCP (n = 12). Glide-path preparation was performed using an automated pecking device. During glide-path preparation, the screw-in force and clockwise and counterclockwise torques were recorded and the number of pecking motions required to reach the working length was determined. The centering ratio was calculated after glide-path preparation using stereomicroscopic images. Data were analyzed using one-way analysis of variance with the Games-Howell post hoc test and the Kruskal-Wallis test with Bonferroni correction. PULS_ART generated a lower maximum screw-in force than PULS_CON. The average number of pecking motions required to reach the working length by HEDG_ART was lower than that by HEDG_CON. The mean centering ratios of PULS_CON and HEDG_CON were - 0.04 and - 0.06, respectively, while those of PULS_ART, HEDG_ART, and WOGG_RCP were 0.09, 0.01, and 0.08, respectively. The ART mode reduced the screw-in force of PULS and enabled faster glide-path preparation with the HEDG file.

Buckling resistance, torque, and force generation during retreatment with D-RaCe, HyFlex Remover, and Mtwo retreatment files.

Objectives: This study compared the buckling resistance of 3 nickel-titanium (NiTi) retreatment file systems and the torque/force generated during retreatment. Materials and Methods: The buckling resistance was compared among the D-RaCe (DR2), HyFlex Remover, and Mtwo R25/05 retreatment systems. J-shaped canals within resin blocks were prepared with ProTaper NEXT X3 and obturated by the single-cone technique with AH Plus. After 4 weeks, 4 mm of gutta-percha in the coronal aspect was removed with Gates-Glidden drills. Retreatment was then performed using DR1 (size 30, 10% taper) followed by DR2 (size 25, 4% taper), HyFlex Remover (size 30, 7% taper), or Mtrwo R25/05 (size 25, 5% taper) (15 specimens in each group). Further apical preparation was performed with WaveOne Gold Primary. The clockwise torque and upward force generated during retreatment were recorded. After retreatment, resin blocks were examined using stereomicroscopy, and the percentage of residual filling material in the canal area was calculated. Data were analyzed using 1-way analysis of variance with the Tukey test. Results: The HyFlex Remover files exhibited the greatest buckling resistance (p < 0.05), followed by the Mtwo R25/05. The HyFlex Remover and Mtwo R25/05 files generated the highest maximum clockwise torque and upward force, respectively (p < 0.05). The DR1 and DR2 files generated the least upward force and torque (p < 0.05). The percentage of residual filling material after retreatment was not significantly different between file systems (p > 0.05). Conclusions: NiTi retreatment instruments with higher buckling resistance generated greater clockwise torque and upward force.

Evaluation of design, mechanical properties, and torque/force generation of heat-treated NiTi glide path instruments.

BACKGROUND: Recently, various kinds of heat-treated nickel-titanium (NiTi) glide path instruments have been manufactured. This study aimed to investigate design, phase transformation behavior, mechanical properties of TruNatomy Glider (#17/02), V Taper 2H (#14/03), and HyFlex EDM (#15/03) and compare torque/force generated during simulated glide path preparation with them. METHODS: The designs and phase-transformation behaviors of the instruments were examined via scanning electron microscopy (n = 3) and differential scanning calorimetry (n = 2). Their bending (n = 15), torsional (n = 15), and cyclic fatigue resistances (n = 15) were tested. The ultimate strength and distortion angle were obtained from torsional resistance test. The number of cycles to failure (NCF) was calculated from cyclic fatigue resistance test. The preparation of the glide path was simulated using a double-curved artificial canal (n = 15), and the maximum torque and screw-in forces were measured. Data except NCF was compared between brands with one-way ANOVA with Tukey's honestly significant difference test. NCF was analyzed via Kruskal-Wallis and Mann-Whitney U tests. RESULTS: TruNatomy Glider had the greatest number of threads. TruNatomy Glider showed progressive taper, while V Taper 2H and HyFlex EDM had constant taper. The austenitic transformation-finish temperatures of all the instruments were above body temperature. V Taper 2H demonstrated significantly lower ultimate strength, higher distortion angle, and a higher number of cycles to failure compared with HyFlex EDM and TruNatomy Glider (p < 0.05). The maximum torque generated during preparing glide path was lowest for V Taper 2H, and the maximum screw-in force was lowest for HyFlex EDM (p < 0.05). TruNatomy Glider generated the highest torque and screw-in force during the apical preparation. CONCLUSIONS: V Taper 2H #14/03 showed superior cyclic fatigue resistance and lower ultimate strength. TruNatomy Glider generated greater clockwise torque and screw-in force during apical preparation. The mechanical properties, torque, and screw-force was affected by design of heat-treated glide path instruments. Cervical pre-flaring prior to glide path instrument is recommended.

Physicochemical and biological properties of four calcium silicate-based endodontic cements.

Background/purpose: Several brands of calcium silicate-based cements (CSBCs) are currently marketed. Here we compared physicochemical and biological properties of new products Ortho MTA (BioMTA), Retro MTA (BioMTA), and EZ-Seal (Ezekiel) to widely used ProRoot MTA (Dentsply Tulsa). Materials and methods: CSBCs were analyzed by X-ray diffractometry and examined by scanning electron microscopy. Elemental composition was determined by energy dispersive spectroscopy. Particle size was measured by particle size analyzer. Human stem cells from apical papilla (SCAPs) were incubated with eluates from CSBCs. Survival of SCAP cells was evaluated with MTT assay. The Alizarin red S stain was used to identify calcified nodules formed in SCAP cultures. The effects of CSBC eluates on SCAP proliferation and migration were examined using an in-vitro scratch "wound-healing" assay. Results: All CSBC specimens showed similar X-ray diffraction patterns. The average particle size of EZ-Seal was smaller than ProRoot MTA, Ortho MTA, and Retro MTA (P < 0.001). The least cytotoxicity of eluates was found for EZ-Seal. In the Alizarin red S staining test, calcified nodules were observed in cultures with ProRoot MTA, Ortho MTA, and Retro MTA, however, no calcified nodules were observed in cultures with EZ-Seal. SCAP proliferation and migration capacity in presence of EZ-Seal was higher than with ProRoot MTA, Ortho MTA, and Retro MTA (P < 0.001). Conclusion: EZ-Seal has a smaller average particle size and a better cytocompatibility than all other examined CSBCs.

Effect of bioactive glass addition on the physical properties of mineral trioxide aggregate.

BACKGROUND: The addition of bioactive glass (BG), a highly bioactive material with remineralization potential, might improve the drawback of weakening property of mineral trioxide aggregates (MTA) when it encounters with body fluid. This study aims to evaluate the effect of BG addition on physical properties of MTA. METHODS: ProRoot (MTA), and MTA with various concentrations of BG (1, 2, 5 and 10% BG/MTA) were prepared. Simulated body fluid (SBF) was used to investigate the effect of the storage solution on dentin remineralization. Prepared specimens were examined as following; the push-out bond strength to dentin, compressive strength, setting time solubility and X-ray diffraction (XRD) analysis. RESULTS: The 2% BG/MTA showed higher push-out bond strengths than control group after 7 days of SBF storage. The 2% BG/MTA exhibited the highest compressive strength. Setting times were reduced in the 1 and 2% BG/MTA groups, and solubility of all experimental groups were clinically acceptable. In all groups, precipitates were observed in dentinal tubules via SEM. XRD showed the increased hydroxyapatite peaks in the 2, 5 and 10% BG/MTA groups. CONCLUSION: It was verified that the BG-added MTA increased dentin push-out bond strength and compressive strength under SBF storage. The addition of BG did not negatively affect the MTA maturation reaction; it increased the amount of hydroxyapatite during SBF maturation.

Characterization of Histopathology and Microbiota in Contemporary Regenerative Endodontic Procedures: Still Coming up Short.

INTRODUCTION: This study aimed to investigate microbiota and the histopathology of infected immature teeth microenvironments after disinfection with calcium hydroxide, triple antibiotic paste, and a synthetic antimicrobial peptide (synthetic human beta-defensin-3-C15) for regenerative endodontic procedures (REPs). The null hypothesis was that there is no difference among intracanal medications on disinfection in REPs. METHODS: Pulp necrosis and periapical lesions were induced in immature beagle dog premolars. Block randomized teeth were uninfected (negative control, n = 6), left infected (positive control, n = 6), or medicated with a disinfectant (n = 6/group). After disinfection (2 weeks), teeth were reaccessed, irrigated with 17% EDTA, blood clot induced, sealed with ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), and restored with resin-modified glass ionomer. Animals were monitored radiographically and euthanized (12 weeks) for histopathologic and metagenomic analyses. RESULTS: REP-treated roots showed radiographic repair of periapical radiolucency (67.65%, 23/34), continued root development (73.53%, 25/34), and apical closure (70.59%, 24/34) regardless of the disinfectant used (P > .05). Canal microenvironments histologically devoid of bacteria contained new mineralized and pulp-like tissues in characteristic patterns that varied by disinfectant. Next-generation sequencing (16S ribosomal RNA) identified Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes as dominant phyla of microbiota in immature teeth. Infection-induced teeth showed changes in diversity and richness of microbiota from negative controls. Compared with positive controls, all treated teeth exhibited depleted operational taxonomic units, with lower phylogenic diversity from synthetic human beta-defensin-3-C15-treated teeth. CONCLUSIONS: There were no differences among the medicaments investigated in radiologic treatment outcomes, but disinfectants in REPs showed altered microbiota from normal and diseased immature teeth with different histologic patterns of regeneration.

Sealing Ability of AH Plus and GuttaFlow Bioseal.

The objective of root canal obturation is to achieve a fluid-tight seal. Recently, GuttaFlow bioseal (GB), a root canal sealer composed of polydimethylsiloxane, gutta-percha particles, and bioactive glass ceramics, has been developed, to enhance the sealing ability of root canal filling material. The objective of this study was to assess the sealing ability of GB using a subnanoliter-scaled fluid-flow measuring device and to compare with that of AH Plus (AH). The fluid flow in root canal-filled teeth using either gutta-percha cone (GP) with AH (GAR; n = 10) or GP with GB (GBR; n = 10) and in GP inserted in AH blocks (GA; n = 10) or GP inserted in GB blocks (GB; n = 10) was measured. In addition, fluid flow in sealer blocks of AH (A; n = 10) and GB (B; n = 10), which served as negative controls, was measured. Root canal-filled teeth using GP without any sealer (GR) acted as positive controls (n = 10). The leakage was obtained by calculating the volume of moved water by time (s), after stabilization of the fluid flow was achieved. Statistical analysis was performed using the Kruskal-Wallis test and Mann-Whitney U-test with Bonferroni correction. A p value less than 0.00238 (0.05/21) was considered significantly different. The mean leakages (nL/s) in the groups are as follows: GAR, 0.0958 ± 0.0543; GBR, 0.0223 ± 0.0246; GA, 0.0644 ± 0.0803; GB, 0.0267 ± 0.0182; A, 0.0055 ± 0.0057; B, 0.0052 ± 0.005; and GR, 0.2892 ± 0.3018. The mean leakage in the GBR group was lower than that in the GAR group (p = 0.001), while the mean leakages in the GA and GB groups were not significantly different. GuttaFlow bioseal can be useful in single-cone obturation technique.

Morphological measurements of two separate mesiobuccal canals in maxillary first molars using micro-computed tomography.

OBJECTIVES: To obtain radicular measurements of two separate mesiobuccal (MB) root canals in maxillary first molars using micro-computed tomography (µCT) with customized software. MATERIALS AND METHODS: Human maxillary first molar MB roots (N = 36) with two separate canals (MB1, MB2) and apical foramina were scanned by µCT and analyzed with Kappa2 software to reconstruct three-dimensional (3D) surface models of roots and canals. These models were sectioned at 0.1 mm intervals perpendicular to the central axis of each canal. Canal widths, 3D curvatures, and surrounding dentine thicknesses were measured concurrently on each section. Dentine thicknesses were analyzed statistically for differences between each direction and the different levels of both canals. RESULTS: Dentine walls around MB1 were thicker than MB2 (p < 0.05). Thinnest dentine was most often located at disto-inside direction in both canals. Canal widths were significantly smaller in MB2 than MB1 (p < 0.01). Apical constrictions were smaller (p < 0.05) and further (p < 0.05) from the apex in MB2 than MB1. Canal curvatures were greatest in the apical third of both canals (p < 0.001), and they were greater in MB2 than MB1 (p < 0.05). CONCLUSIONS: MB2 canals had shorter lengths, smaller widths, and more severe curvatures and were surrounded by thinner dentine walls. In MB2, apical constrictions were between 1 and 2 mm from the apex, compared to about 1 mm for MB1. CLINICAL RELEVANCE: These detailed measurements and in-depth 3D analyses of maxillary first molar MB roots with two separate canals and apical foramina provide morphologic references for root canal therapy.

In Vitro Characterization of Dental Pulp Stem Cells Cultured in Two Microsphere-Forming Culture Plates.

Various three-dimensional (3D) culture methods have been introduced to overcome the limitations of in vitro culture and mimic in vivo conditions. This study aimed to evaluate two microsphere-forming culture methods and a monolayer culture method. We evaluated cell morphology, viability, osteo-, adipo-, and chondrogenic differentiation potential of dental pulp stem cells (DPSCs) cultured in 3D culture plates: ultra-low attachment (ULA) and U-bottomed StemFit 3D (SF) plates, and a two-dimensional (2D) monolayer plate. RNA sequencing (RNA-seq) revealed differentially expressed gene (DEG) profiles of the DPSCs. In contrast to an increasing pattern in the 2D group, cell viability in 3D groups (ULA and SF) showed a decreasing pattern; however, high multilineage differentiation was observed in both the 3D groups. RNA-seq showed significantly overexpressed gene ontology categories including angiogenesis, cell migration, differentiation, and proliferation in the 3D groups. Hierarchical clustering analysis revealed a similar DEG regulation pattern between the 3D groups; however, a comparatively different DEG was observed between the 2D and 3D groups. Taken together, this study shows that DPSCs cultured in microsphere-forming plates present superior multilineage differentiation capacities and demonstrate higher DEG expression in regeneration-related gene categories compared to that in DPSCs cultured in a conventional monolayer plate.

Bending resistance and cyclic fatigue resistance of WaveOne Gold, Reciproc Blue, and HyFlex EDM instruments.

BACKGROUND/PURPOSE: Several single-file systems manufactured using different heat treatment and operated by different kinematics have been released. This study compared the bending resistance and cyclic fatigue resistance of three NiTi files, and examined their phase-transformation behavior. MATERIALS AND METHODS: WaveOne Gold Primary (WOG), Reciproc Blue R25 (RPB), and HyFlex EDM OneFile (HDM) were tested (N = 40/instrument). A vertical load was applied to a point 3 mm from the tip, and the stress was measured until a displacement of 3 mm. Tests were conducted at either room temperature (RT: 22 °C) or body temperature (BT: 37 °C) (n = 10). Cyclic fatigue resistance tests were performed in an artificial canal, which had a curvature angle of 40° and a 5-mm radius. Tests were conducted at either RT or BT (n = 10). Instruments were operated according to the manufacturers' instructions. Test results were analyzed using the Kruskal-Wallis and the Mann-Whitney tests. Additional three instruments of each brand were subjected to differential scanning calorimetry (DSC). RESULTS: At RT the bending resistance of three files were not significantly different. However, at BT the bending resistance of RPB was highest, followed by WOG, and HDM (P < 0.05). At RT, RPB demonstrated the longest fracture time, followed by HDM, and WOG (P < 0.05). At BT, HDM had the longest fracture time, followed by RPB, and WOG (P < 0.05). The WOG, RPB consisted of austenite in a considerable proportion, whereas HDM was mainly martensite state at BT. CONCLUSION: HDM presented superior flexibility and cyclic fatigue resistance at BT.

Effect of autoclave sterilization on cyclic fatigue and torsional fracture resistance of NiTi rotary instruments.

The purpose of this study is to assess the effect of autoclave sterilization on the cyclic fatigue and torsional fracture resistance of ProTaper Universal (PTU), K3XF, HyFlex EDM (EDM), and TF adaptive (TFA). Sixty instruments from each file type were divided into two categories for cyclic fatigue group (CGr) and torsional fracture group (TGr). CGr and TGr were divided into three subgroups, respectively, consisting of ten instruments from each file type. Cyclic fatigue fracture test was performed using artificial canal made of stainless steel, and the mean number of cycles to failure (NCF) were determined. CGr1, the files were tested to establish baseline for NCF; CGr2, the files were tested cyclic fatigue after 10 cycles of autoclave; CGr3, instruments were autoclaved after being cycled to 25, 50, and 75% of corresponding NCF determined in CGr1, followed by cyclic fatigue test. The torsional fracture test was performed without autoclave (TGr1), after 3-cycle autoclave (TGr2), and 7-cycle autoclave (TGr3), respectively, which evaluated maximum torque and angular deflection. NCF, maximum torque and angular deflection were compared using one-way ANOVA with Bonferroni test. Two-way ANOVA was performed to determine the interaction between 'autoclave treatment' and 'type of NiTi file'. EDM showed highest NCF within the same autoclave treatment. TFA presented the lowest maximum torque and the highest angular deflection, and PTU presented the lowest angular deflection. Within the same NiTi file systems, most of NCF, maximum torque and angular deflection of tested files were not significantly influenced by autoclave condition.

Torsional and Bending Properties of V Taper 2H, ProTaper NEXT, NRT, and One Shape.

Nickel-titanium (NiTi) rotary files have enabled efficient root canal preparations that maintain the canal center with fewer aberrations compared to hand files. However, NiTi rotary files are susceptible to fracture, which can thereby compromise root canal treatment. Therefore, NiTi files have been developed to enhance fracture resistance by modifying design and thermal treatment. The objective of this study was to compare the torsional fatigue resistance and bending resistance of NiTi files manufactured from different alloys and treatments. ProTaper NEXT X2 (PTN; M-wire), V taper 2H (V2H; controlled memory wire), NRT (heat-treated), and One Shape (OS; conventional alloy) instruments of tip size #25 were compared. Torsional fatigue was evaluated by embedding the 3 mm tip of each instrument (N = 10/brand) in resin and the repetitive application of torsional stress (300 rpm, 1.0 N·cm) by an endodontic motor with autostop when the file fractured. The number of loading cycles to fracture was recorded and analyzed by Kruskal-Wallis and Mann-Whitney U tests with Bonferroni's correction. Bending resistance of the instruments was tested using a cantilever bending test to the 3 mm point from the tip (N = 10/brand). The stress was measured when deflection of 3 mm was subjected and statistically analyzed with a one-way analysis of variance and Tukey's honest significance difference test (α = 0.05). V2H withstood the highest number of load applications during torsional fatigue testing (p < 0.05), followed by NRT, PTN, and OS, where the differences between NRT and PTN (p=0.035) and between PTN and OS (p=0.143) were not statistically significant. V2H showed the lowest bending stiffness, followed by NRT, PTN, and OS (p < 0.001). Thermal treatment of NiTi wire resulted in improved mechanical properties, and controlled memory wire provided improved flexibility and torsional fatigue resistance.

Synthetic Human ß Defensin-3-C15 Peptide in Endodontics: Potential Therapeutic Agent in Streptococcus gordonii Lipoprotein-Stimulated Human Dental Pulp-Derived Cells.

Human ß defensin-3-C15, an epithelium-derived cationic peptide that has antibacterial/antifungal and immuno-regulatory properties, is getting attention as potential therapeutic agent in endodontics. This study aimed to investigate if synthetic human ß defensin-3-C15 (HBD3-C15) peptides could inhibit inflammatory responses in human dental pulp cells (hDPCs), which had been induced by gram-positive endodontic pathogen. hDPC explant cultures were stimulated with Streptococcus gordonii lipoprotein extracts for 24 h to induce expression of pro-inflammatory mediators. The cells were then treated with either HBD3-C15 (50 µg/mL) or calcium hydroxide (CH, 100 µg/mL) as control for seven days, to assess their anti-inflammatory effects. Quantitative RT-PCR analyses and multiplex assays showed that S. gordonii lipoprotein induced the inflammatory reaction in hDPCs. There was a significant reduction of IL-8 and MCP-1 within 24 h of treatment with either CH or HBD3-C15 (p < 0.05), which was sustained over 1 week of treatment. Alleviation of inflammation in both medications was related to COX-2 expression and PGE2 secretion (p < 0.05), rather than TLR2 changes (p > 0.05). These findings demonstrate comparable effects of CH and HDB3-C15 as therapeutic agents for inflamed hDPCs.

Influence of proper or reciprocating optimum torque reverse kinematics on cyclic fatigue of four single files.

AIM: The aim of the present study was to evaluate the resistance to cyclic fatigue of heat-treated single files used in proper or in reciprocating optimum torque reverse motions. METHODS: Ninety-six HyFlex electrical discharge machining (EDM), Reciproc R25 (Rec), WaveOne Primary (WO), and WaveOne Gold (WOG) Primary were used. Resistance to cyclic fatigue was determined by recording time to fracture in a stainless steel artificial canal. Differential scanning calorimetric analysis was performed. Data were analyzed by two-way analysis of variance and Bonferroni post-hoc tests at 0.05. RESULTS: In both movements, HyFlex EDM showed higher time to fracture than other files (P < 0.0001). Rec showed higher time to fracture than WO (P < 0.0001), while WOG showed higher cyclic fatigue resistance than Rec and WO with both movements (P < 0.005). CONCLUSIONS: Reciprocating optimum torque reverse motion improved significantly cyclic fatigue resistance of gold and controlled memory wire single files.

Cyclic fatigue resistance, torsional resistance, and metallurgical characteristics of M3 Rotary and M3 Pro Gold NiTi files.

OBJECTIVES: To evaluate the mechanical properties and metallurgical characteristics of the M3 Rotary and M3 Pro Gold files (United Dental). MATERIALS AND METHODS: One hundred and sixty new M3 Rotary and M3 Pro Gold files (sizes 20/0.04 and 25/0.04) were used. Torque and angle of rotation at failure (n = 20) were measured according to ISO 3630-1. Cyclic fatigue resistance was tested by measuring the number of cycles to failure in an artificial stainless steel canal (60° angle of curvature and a 5-mm radius). The metallurgical characteristics were investigated by differential scanning calorimetry. Data were analyzed using analysis of variance and the Student-Newman-Keuls test. RESULTS: Comparing the same size of the 2 different instruments, cyclic fatigue resistance was significantly higher in the M3 Pro Gold files than in the M3 Rotary files (p < 0.001). No significant difference was observed between the files in the maximum torque load, while a significantly higher angular rotation to fracture was observed for M3 Pro Gold (p < 0.05). In the DSC analysis, the M3 Pro Gold files showed one prominent peak on the heating curve and 2 prominent peaks on the cooling curve. In contrast, the M3 Rotary files showed 1 small peak on the heating curve and 1 small peak on the cooling curve. CONCLUSIONS: The M3 Pro Gold files showed greater flexibility and angular rotation than the M3 Rotary files, without decrement of their torque resistance. The superior flexibility of M3 Pro Gold files can be attributed to their martensite phase.

Novel Calcium Zirconate Silicate Cement Biomineralize and Seal Root Canals.

This study evaluated the sealing ability of gutta-percha (GP) with a calcium silicate-based sealer and a novel calcium zirconate containing calcium silicate cement (ZC). The root canals of the extracted premolars were prepared, which were then randomly allocated to three experimental groups (12 root canals per group) for obturation by continuous wave of condensation with the GP and AH 26 sealer (CW); obturation using a single GP with a calcium silicate-based EndoSequence BC sealer (SC); or obturation with ZC. The roots were inserted into sterile Eppendorf tubes, which were inoculated coronally with Porphyromonas gingivalis. The amount of endotoxin leakage into the apical reservoirs were measured using the Limulus Amebocyte Lysate (LAL) assay over 21 days, with comparisons made using one-way ANOVA and Scheffe's tests (α = 0.05). After 21 days, 75% of the canals that had been obturated by SC, 50% of those obturated by CW and 42% of those obturated by ZC showed endotoxin leakage. The amount of leakage was higher in the SC canals than in the CW (p = 0.031) or ZC (p = 0.03) canals, although there was no significant difference in the amount of leakage for CW and ZC (p > 0.05). X-ray diffraction revealed the presence of tricalcium silicate (Ca3SiO5) and calcium zirconate (CaZrO3) in the synthesized ZC. Scanning electron microscopy revealed mineralized precipitates on the dentin of canals obturated by ZC. The novel calcium zirconate silicate cement appears to promote biomineralization and seal root canals at least as effectively as the conventional sealer.

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.

Dentinal tubule sealing effects of 532-nm diode-pumped solid-state laser, gallic acid/Fe3+ complex, and three commercial dentin desensitizers.

The purpose of this study was to compare dentinal tubule sealing effects of a 532-nm diode-pumped solid-state (DPSS) laser, gallic acid/Fe3+ complex, and three commercially available dentin desensitizers. Human premolars (n = 44) extracted for orthodontics had standardized cervical cavities prepared, etched (37% phosphoric acid) and randomly assigned to either a control (n = 4), or one of five treatment groups (n = 8/group). Desensitizing treatments were either a 532-nm DPSS laser, gallic acid/Fe3+ complex, oxalate-based Super Seal™ (SS), DIO™ Enamel Coating Pen Pro Tooth (Dio), or adhesive-type Hybrid Coat™ (HC). Dentinal fluid flow (DFF) was monitored continuously in real time during the application of each desensitizing agent, by using a nanoliter-scaled fluid flow-measuring device. Following treatment, morphological changes on dentinal surfaces and within tubules were observed by scanning electron microscopy (SEM). DFF rates were significantly reduced after treatment in all experimental groups (P < 0.05), except SS (P > 0.05). The gallic acid/Fe3+ complex reduced DFF rates the most, and significantly (P < 0.05) more than the three commercial dentin desensitizers. There were no significant differences in DFF reduction rates between the gallic acid/Fe3+ complex and the DPSS laser groups (P > 0.05). There were no significant differences in DFF reduction rates among the three commercial dentin desensitizers (P > 0.05). SEM examination of treated dentin showed that the degree of occlusion of dentinal tubules correlated closely with the corresponding reduction in DFF rates. The gallic acid/Fe3+ complex and 532-nm DPSS laser were superior to other desensitizing methods in occluding dentinal tubules and reducing DFF rates.

Intratubular Biomineralization in a Root Canal Filled with Calcium-Enriched Material over 8 Years.

This case report describes intratubular biomineralization in root canal, filled with calcium-enriched material after 8 years of clinical maintenance. The schematic findings of dentinal tubules were investigated with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The root canal obturation material was closely adapted to root dentin surface, suggesting the possibility of chemical bonding between the two interfaces. SEM and EDS observation of dentinal tubules showed intratubular biomineralized crystal structures with Ca/P ratio in a range of 1.30-2.12, suggesting bioactive capacity of calcium-enriched material.

Antifungal Effects of Synthetic Human Beta-defensin-3-C15 Peptide on Candida albicans-infected Root Dentin.

INTRODUCTION: The aim of this study was to assess the antifungal efficacy of a synthetic human beta-defensin-3-C15 peptide (HBD3-C15) in Candida albicans-infected human root dentin. METHODS: Standardized root dentin blocks were prepared (6-mm thick, 0.7-mm-wide canal) from single-rooted human permanent premolars and infected with C. albicans for 3 weeks. They were randomly divided into 4 groups (n = 8/group), and their canals were filled with calcium hydroxide (CH), HBD3-C15 peptide, or chlorhexidine digluconate (CHX, 2%) as disinfectants or saline as control. After 1 week of disinfection, dentinal debris were harvested at depths of 200 and 400 µm from the canal lumen, and incubated in Yeast broth for 72 hours at 37°C. Then, colony-forming units (CFU) were measured to assess the antifungal efficacy of each medicament and analyzed statistically. RESULTS: All medicaments showed significantly lower CFU than saline (P < .05), and their antifungal efficacies were similar at both 200- and 400-µm tubular depths (P > .05). HBD3-C15 had similar antifungal efficacy to that of CHX at both depths (P > .05), and both medicaments had significantly lower CFU than CH at both depths (P < .05). CONCLUSIONS: In this ex vivo model of C. albicans-infected human root dentin, the antifungal efficacy of synthetic HBD3-C15 was comparable with CHX.