Surface porosity of hand-mixed, syringe-mixed and encapsulated set endodontic sealers.

OBJECTIVE: The objective of this study was to investigate the surface porosity of hand-mixed, syringe-mixed and encapsulated set endodontic sealers using image analysis. STUDY DESIGN: Eight different root canal sealers (AD Seal/Meta Biomed; AH Plus/Dentsply; MM Seal/Micromega; AH Plus Jet/Dentsply; EndoREZ/Ultradent; Epiphany/Pentron; GuttaFlow/Coltène; RealSeal/Sybron Endo) were prepared in accordance with the manufacturer's recommendations and dispensed into plastic rings (n = 10/group). Following set of the specimens, scanning electron photomicrographs of the sealer surfaces were taken at standard magnification. The area fraction and the minimum-maximum diameters of surface pores were calculated on the micrographs using ImageJ open-source image analysis software. Statistical comparisons were made between the sealers with respect to the area fractions and number of pores (Kruskal-Wallis test, P < .05). RESULTS: The endodontic sealers differed significantly in both the percentage of area fraction and pore count (P < .001). The surface porosity of the methacrylate-based sealers Epiphany and RealSeal were significantly lower than those of resin- and silicone-based sealers. With the exception of AD Seal, hand-mixed sealers displayed significantly higher surface porosity than those of syringe-mixed ones (P < .001). The encapsulated sealer GuttaFlow exhibited the highest surface area fraction of pores. CONCLUSION: The mixing method influences the surface porosity of set endodontic sealers.

Effects of different irrigation regimens on the sealing properties of repaired furcal perforations.

OBJECTIVE: The pulp chamber is inevitably exposed to irrigants during endodontic therapy. This study aimed to investigate whether different irrigation regimens would alter the sealing ability of repaired furcal perforations. STUDY DESIGN: Pulp chambers of 90 extracted human molars were accessed, after which standardized diamond bur-cut perforations were created in the center of the pulp chamber floor. The canal orifices and the apical end of roots were sealed with acid-etch composite resin. Eighty teeth were randomly divided into 2 groups (n = 40/group) according to the material used for repairing the perforation defects: (1) Mineral trioxide aggregate (MTA), (2) Super-EBA. The remaining teeth (n = 10) served as controls. The specimens were further subgrouped according to the irrigation regimens applied over the repair site (n = 10/group): (a) 5.25% NaOCl, (b) 5.25% NaOCl + EDTA, (c) 5.25% NaOCl + MTAD, and (d) No irrigation. Coronal leakage was measured by the fluid-filtration method at 1 day and 1 week. RESULTS: Fluid conductance was not affected by the type of repair material (P = .964) or time (P = .726), but was affected significantly by the irrigation regimens in the following ranking: (P < .001): NaOCl < or = No Irrigation < NaOCl + MTAD < or = NaOCl + EDTA. CONCLUSION: The sealing ability of furcal perforations repaired with MTA or Super-EBA were differentially affected by exposure to the tested irrigation regimens.

Time-dependent decalcifying effects of endodontic irrigants with antibacterial properties.

The aim of this study was to investigate the extent of calcium ion (Ca(2+)) removal on root dentin after treatment with 1.25% NaOCl, 2.5% NaOCl, 5.25% NaOCl, 2% chlorhexidine (CHX), 2% iodine potassium iodide (IKI), and MTAD in 3 immersion time periods. Extracted human mandibular premolars were bisected longitudinally, and the root halves (n = 70) were isolated with nail varnish, leaving the root canal exposed. The specimens were immersed in the test solutions, during which the amount of Ca(2+) release into the solutions was determined at 5, 10, and 15 minutes by flame photometry. The decalcifying effect of 5%, 2.5%, and 1.25% NaOCl and 2% IKI significantly increased within time (P < .05), with 5% NaOCl extracting the greatest amount of Ca(2+) at all treatment times. For 2% CHX and distilled water, a significant increase in the amount of Ca(2+) extraction from root dentin was only evident at 10 minutes (P < .05) and did not change at 15-minute readings. Between the 5- to 10-minute and 10- to 15-minute intervals, the greatest amount of increase in the rate of Ca(2+) extraction from root dentin was observed in the 2.5% NaOCl group. At 15 minutes, 2% CHX and distilled water showed the least amount of change. Among the test solutions, MTAD extracted the least amount of Ca(2+) at 5 minutes.

In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate as a potential tooth transport medium: viability and apoptosis in L929 fibroblasts.

Casein phosphopeptides (CPP) are derived from casein, which accounts for 80% of the total protein in bovine milk . The purpose of this in vitro study was to evaluate the potential use of a CPP-amorphous calcium phosphate (CPP-ACP) preparation as a transport medium for avulsed teeth. L929 fibroblastic cell line was plated in 24-well culture plates. Following incubation, the cells were treated with 10(-3), 10(-4), 10(-6), 10(-8), 10(-12) dilutions of a water-based CPP-ACP paste (Tooth Mousse, GC Corp., Tokyo, Japan). Untreated cells served as controls. The L929 cells were counted at the 1st, 3rd and 7th days. Propidium iodide/acridine orange staining was used to assess apoptosis of treated cells and of the positive control. For each concentration (dilution), statistical analysis of cell survival within time was performed using two-way analysis of variance (ANOVA, P = 0.05). One way ANOVA and Tukey tests were applied to compare the effect of different concentrations on cell survival at each evaluation day (P = 0.05). Except for the 10(-3) and 10(-4) dilutions, all groups demonstrated an increase in cell numbers at days 1 and 3, followed by a decrease at day 7. Irrespective of the increase or decrease in cell viability, time-dependent changes for each dilution group were significantly different. Cells in the 10(-3) and 10(-4) dilution groups demonstrated a rapid apoptotic response. A relatively few number of apoptotic cells were observed in the 10(-6) and 10(-8) dilution groups, while no sign of apoptosis was evident in the 10(-12) dilution group and control. These results suggest that when highly diluted, the tested CPP-ACP preparation may help preserve L929 cell viability in the short term without inducing apoptosis.

Comparison of the area of resin-based sealer and voids in roots obturated with Resilon and gutta-percha.

The aim of this study was to compare the cross-sectional area of sealer plus voids of Epiphany sealer surrounding root fillings completed with Resilon cones and laterally compacted gutta-percha. The root canals of extracted human mandibular premolars were prepared to a final size of 40 (0.06 taper). The teeth were then randomly assigned into 2 groups (n = 12/group) for the filling procedures in conjunction with Epiphany sealer: group 1, Resilon cones, and group 2, gutta-percha. Horizontal sections were obtained every 1 mm up to 5 mm from the apical foramen. The sections were digitally photographed under magnification, and the cross-sectional area of the root canal and the area occupied by the sealer and voids were calculated, after which statistical comparisons were made. No differences were found between the sealer plus void or void area of Resilon or gutta-percha groups at any level of sectioning (P > .05). Comparisons within each obturation group showed that there was no significant difference between any level of sectioning with regard to the ratio of sealer plus void area or void area to that of the root canal (P > .05). Within the experimental conditions of the present study, both obturating techniques with the Epiphany sealer exhibited similar amounts of sealer and void area, regardless of the apical level of sectioning compared.

Comparative evaluation of three nickel-titanium instrumentation systems in human teeth using computed tomography.

This study investigated several parameters of root canal preparation with three different rotary NiTi systems: Hero Shaper, ProTaper, and RaCe. The parameters evaluated were: changes in root canal volume and cross-sectional area, canal transportation, and working time. Curved, mesial molar roots were scanned in a computed tomography (CT) unit before and after instrumentation. Cross-sectional views of each canal were obtained at 1 mm intervals. Postinstrumentation volume and cross-sectional area of root canals and the extent of transportation were calculated using image analysis software and, thereafter, subjected to statistical analysis. ProTaper removed significantly more dentin than Hero Shaper (p < 0.05). Instrumentation increased the cross-sectional area at all cutplanes, while the difference between test groups was not significant (p > 0.05). RaCe files significantly transported the canals at the coronal level (p < 0.05). There was no difference between any rotary systems in regards to working time.