Blocking systemic nitric oxide production alters neuronal activation in brain structures involved in cardiovascular regulation during polymicrobial sepsis

In a previous study, we concluded that overproduction of nitric oxide (NO) by inducible nitric Oxide synthase (iNOS) in the late phase of sepsis prevents hypothalamic activation, blunts vasopressin secretion and contributes to hypotension, irreversible shock and death. The aim of this follow-up study was to evaluate if the same neuronal activation pattern happens in brain structures related to cardiovascular functions. Male Wistar rats received intraperitoneal injections of aminoguanidine, an iNOS inhibitor, or saline 30 min before cecal ligation and puncture (CLP) or sham surgeries. The animals were perfused 6 or 24 h after the surgeries and the brains were removed and processed for Fos immunocytochemistry We observed an increase (P < 0.001) in c-fos expression 6 h after CLP in the area postrema (AP), nucleus of he tractus solitarius (NTS), ventral lateral medulla (VLM), locus coeruleus (LC) and parabrachial nucleus (PB). At 24 h after CLP, however, c-fos expression was strongly decreased in all these nuclei (P < 0.05), except for the VLM. Aminoguanidine reduced c-fos expression in the AP and NTS at 6 h after CLR but showed an opposite effect at 24 h, with an increase in the AP, NTS, and also in the VLM. No such effect was observed in the LC and PB at 6 or 24 h. In all control animals, c-fos expression was minimal or absent. We conclude that in the early phase of sepsis iNOS-derived NO may be partially responsible for the activation of brain structures related to cardiovascular regulation. During the late phase, however, this activation is reduced or abolished. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Flat-Oval Root Canal Preparation with Self-Adjusting File Instrument: A Micro-Computed Tomography Study

Introduction: The aim of this study was to evaluate the root canal preparation in flat-oval canals treated with either rotary or self-adjusting file (SAF) by using micro-tomography analysis. Methods: Forty mandibular incisors were scanned before and after root canal instrumentation with rotary instruments (n = 20) or SAF (n = 20). Changes in canal volume, surface area, and cross-sectional geometry were compared with preoperative values. Data were compared by independent sample t test and chi(2) test between groups and paired sample t test within the group (alpha = 0.05). Results: Overall, area, perimeter, roundness, and major and minor diameters revealed no statistical difference between groups (P > .05). In the coronal third, percentage of prepared root canal walls and mean increases of volume and area were significantly higher with SAF (92.0%, 1.44 +/- 0.49 mm(3), 0.40 +/- 0.14 mm(2), respectively) than rotary instrumentation (62.0%, 0.81 +/- 0.45 mm(3), 0.23 +/- 0.15 mm2, respectively) (P < .05). SAF removed dentin layer from all around the canal, whereas rotary instrumentation showed substantial untouched areas. Conclusions: In the coronal third, mean increases of area and volume of the canal as well as the percentage of prepared walls were significantly higher with SAF than with rotary instrumentation. By using SAF instruments, flat-oval canals were homogenously and circumferentially prepared. The size of the SAF preparation in the apical third of the canal was equivalent to those prepared with #40 rotary file with a 0.02 taper. (J Endod 2011;37:1002-1007)

Physicochemical Properties of Methacrylate Resin-based Root Canal Sealers

Introduction: This study assessed in vitro the physicochemical properties of 2 methacrylate resin-based sealers (Epiphany SE and Hybrid Root SEAL), comparing the results with a well-established epoxy resin-based sealer (AH Plus). Methods: Five samples of each material were used for each test (setting time, flow, radiopacity, dimensional change after setting, and solubility) according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57. The samples were assigned to 3 groups: I, AH Plus; II, Epiphany SE; and III, Hybrid Root SEAL. The distilled and deionized water used at the solubility test was submitted to atomic absorption spectrometry to observe the presence of Ca2+, K+, Ni2+, and Zn2+ ions. In addition, the surface morphology of the specimens was analyzed by means of scanning electron microscopy (SEM). Statistical analysis was performed by using one-way analysis of variance and Tukey-Kramer test (P < .05). Results: Flow, radiopacity, and solubility of all sealers were in accordance with ANSI/ADA. The setting time of Hybrid Root SEAL did not agree with ANSUADA requirements. The dimensional change of all sealers was greater than the values considered acceptable by ANSI/ADA. The spectrometry analysis showed significant Ca2+ ions release for AH Plus. In SEM analysis, Hybrid Root SEAL presented spherical monomers with inferior size than AH Plus and Epiphany SE. Conclusions: It might be concluded that physicochemical properties of the tested sealers conformed to ANSI/ADA (2000) standardization, except for the setting time of Hybrid Root SEAL and the dimensional change of all sealers, which did not fulfill the ANSI/ADA requirements. (J Endod 2010;36:1531-1536)

Bond Strength of Fiber Posts to Weakened Roots After Resin Restoration With Different Light-Curing Times

Introduction: This study evaluated the bond strength of translucent fiber posts to experimentally weakened radicular dentin restored with composite resin and polymerized with different light-exposure time. Methods: Roots of 60 maxillary incisors were used. Twenty-four hours after obturation, the filling materials of root canals were removed to a depth of 12 mm, and 4 groups were randomly formed. In 3 groups, root dentin was flared to produce a space between fiber post and canal walls. In the control group, the roots were not experimentally weakened. The flared roots were bulk restored with composite resin, which was light-activated through the translucent post for 40, 80, or 120 seconds. Posts were cemented, and after 24 hours, all roots were sectioned transversely in the coronal, middle, and apical regions, producing 1-mm-thick slices. Push-out test was performed, and failure modes were observed. Results The quantitative analysis showed significant statistical difference only among groups (P <.001). Comparing the weakened/restored groups, composite light-exposure time did not influence the results. Overall, adhesive failures occurred more frequently than other types of failures. Cohesive failures occurred only in the weakened/restored roots. Conclusions Intracanal root restoration with composite resin and translucent fiber posts provided similar or higher bond strength to dentin than the control group, regardless of the light-exposure time used for polymerization. (J Endod 2009;35:1034-1039)

Solubility of Epiphany Endodontic Sealer Prepared with Resinous Solvent

Purpose: To evaluate in vitro the solubility of the Epiphany endodontic filling material Epiphany (Pentron Clinical Technologies, Wallingford, CT) prepared with its resinous solvent. Methods: The specimens were prepared in the following experimental conditions: (1) GI, epiphany without photoactivation; (2) GII, Epiphany prepared with resinous solvent without photoactivation; (3) Gill, Epiphany followed by photoactivation; and (4) GIV, Epiphany prepared with resinous solvent followed by photoactivation. Ten specimens of each group were obtained from Teflon molds with 80% reduction in volume of the specimen`s dimensions based on American National Standard Institute/American Dental Association (ANSI/ADA) Specification No. 57. The samples were weighted and immersed in distilled water for 7 days. After this period, they were removed, dried, and weighed again. Solubility was calculated by using samples weight loss (%). The immersion liquid was evaluated through atomic absorption spectrometry. Results: The sealers without photoactivation were statistically similar (p > 0.05) between themselves (GI = 6.93% and GII = 6.39%) and different from the uncured sealers, which were statistically different between themselves (p < 0.05) (GIII = 3.56% and GIV = 0.47%). Only the Epiphany sealer prepared with resinous solvent followed by photoactivation presented solubility values within ANSI/ADA requirements, liberating the following amounts of ions: 114.43 mu g of Ca(2+)/mL, 2.4 mu g of Mg(2+)/mL, 0.33 mu g of Fe(2+)/mL, 0.11 mu 4g of Zn(2+)/mL, 1.31 mu g of Ni(2+)/mL, and 7.1 mu g of Na(+)/mL. Conclusion: The association of resinous solvent to the Epiphany sealer followed by photoactivation resulted in a filling material with low solubility and expressive liberation of calcium ions. (J Endod 2009;35:715-718)

Atomic Absorption Spectrometry and Scanning Electron Microscopy Evaluation of Concentration of Calcium Ions and Smear Layer Removal With Root Canal Chelators

Aim. The aim of this study was to evaluate the concentration of calcium ions and smear layer removal by using root canal chelators according to flame atomic absorption spectrophotometry and scanning electron microscopy. Forty-two human maxillary central incisors were irrigated with 15% ethylenediaminetetraacetic acid (EDTA), 10% citric acid, 10% sodium citrate, apple vinegar, 5% acetic acid, 5% malic acid, and sodium hypochlorite. The concentration of calcium ions was measured by using flame atomic absorption spectrometry, and smear layer removal was determined by scanning electron microscopy. Mean +/- standard deviation, one-way analysis of variance, Tukey-Kramer, Kruskal-Wallis, Dunn, and kappa tests were used for statistical analysis. The use of 15% EDTA resulted in the greatest concentration of calcium ions followed by 10% citric acid; 15% EDTA and 10% citric acid were the most efficient solutions for removal of smear layer. (J Endod 2009;35:727-730)

IN VITRO FRACTURE RESISTANCE OF GLASS-FIBER AND CAST METAL POSTS WITH DIFFERENT LENGTHS

Statement of problem. Dental fractures can occur in endodontically treated teeth restored with posts. Purpose. The purpose of this study was to evaluate the in vitro fracture resistance of roots with glass-fiber and metal posts of different lengths. Material and methods. Sixty endodontically treated maxillary canines were embedded in acrylic resin, except for 4 mm of the cervical area, after removing the clinical crowns. The post spaces were opened with a cylindrical bur at low speed attached to a surveyor, resulting in preparations with lengths of 6 mm (group 6 mm), 8 mm (group 8 mm), or 10 mm (group 10 mm). Each group was divided into 2 subgroups according to the post material: cast post and core or glass-fiber post (n=30). The posts were luted with dual-polymerizing resin cement (Panavia F). Cast posts and cores of Co-Cr (Resilient Plus) crowns were made and cemented with zinc phosphate. Specimens were subjected to increasing compressive load (N) until fracture. Data were analyzed with 2-way ANOVA and the Tukey-Kramer test (alpha=.05). Results. The ANOVA analysis indicated significant differences (P<.05) among the groups, and the Tukey test revealed no significant difference among the metal posts of 6-mm length (26.5 N +/- 13.4), 8-mm length (25.2 N +/- 13.9), and 10-mm length (17.1 N +/- 5.2). Also, in the glass-fiber post group, there was no significant difference when posts of 8-mm length (13.4 N +/- 11.0) were compared with the 6-mm (6.9 N +/- 4.6) and 10-mm (31.7 N +/- 13.1) groups. The 10-mm-long post displayed superior fracture resistance, and the 6-mm-long post showed significantly lower mean values (P<.001). Conclusions. Within the limitations of this study, it was concluded that the glass-fiber post represents a viable alternative to the cast metal post, increasing the resistance to fracture of endodontically treated canines. (J Prosthet Dent 2009;101:183-188)

Bond Strength of Epiphany Sealer Prepared with Resinous Solvent

This study evaluated in vitro the bond strength of Epiphany sealer prepared with resinous solvent of Epiphany system (Thinning resin) by using a push-out test. Forty maxillary canines were sectioned transversally below the cementoenamel junction to provide 4-mm-thick dentin disks that were centered in aluminum rings and embedded in acrylic resin. Root canals were prepared with tapered diamond bur. Intraradicular dentin was treated with 1% NaOCl for 30 minutes, 17% ethylenediaminetetraacetic acid for 5 minutes, and flushed with distilled water for 1 minute. The specimens were randomly distributed into 4 groups (n = 10) according to the filling material: GI, Epiphany without photoactivation; GII, Epiphany prepared with solvent without photoactivation; Gill, Epiphany followed by photoactivation; and GIV, Epiphany prepared with solvent followed by photoactivation. After the setting time, the specimens were submitted to the push-out test. The highest mean value (14.91 +/- 2.82 MPa) was obtained with Epiphany prepared with solvent followed by photoactivation (GIV), which was statistically different (P < .01) from the other groups. Groups I (8.15 +/- 2.47 MPa), II (9.46 +/- 2.38 MPa), and III (9.80 +/- 2.51 MPa) had inferior bond strength values and were statistically similar among themselves (P > .01). The resinous solvent of Epiphany system increased the bond strength of Epiphany sealer to dentin walls when followed by photoactivation. (J Endod 2009;35: 251-255)

Morphological Alterations of Radicular Dentine Pretreated With Different Irrigating Solutions and Irradiated With 980-nm Diode Laser

Background: The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. Purpose: To evaluate the alterations of dentine irradiated with 980-nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Study design: Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali-quatitative way. The scores were submitted to two-way Kruskal-Wallis and Dunn`s tests. Results: The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P < 0.05) from the laser-irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser-modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. Conclusions: The tested parameters of 980-nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Microsc. Res. Tech. 72:22-27, 2009. (C) 2008 Wiley-Liss, Inc.

Determination of para-Chloroaniline and Reactive Oxygen Species in Chlorhexidine and Chlorhexidine Associated with Calcium Hydroxide

The aim of this study was to determine whether para-chloroaniline (PCA) and/or reactive oxygen species (ROS) are generated by chlorhexidine (CHX) alone or after CHX is mixed with calcium hydroxide at different time points. Mass spectrometry was performed to detect PCA in samples of 0.2% CHX and Ca(OH)2 mixed with 0.2% CHX. High-performance liquid chromatography was used to confirm the presence of CHX in the mixture with Ca(OH)2. The samples were analyzed immediately after mixing and after 7 and 14 days. During the intervals of the experiment, the samples were maintained at 36.5 degrees C and 95% relative humidity. PCA was detected in the 0.2% CHX solution after 14 days. The mixture of CHX with Ca(CH)2 liberated ROS at all time points, but no traces of CHX were present in the mixture as a result of immediate degradation of the CHX. (J Endod 2008;34:1508-1514)

Coronal resistance to fracture of endodontically treated teeth submitted to light-activated bleaching

Objectives: The aim of this study was to assess the fracture resistance of endodontically treated teeth submitted to bleaching with 38% hydrogen peroxide activated by light-emitting diode (LED)-laser system. Methods: Fifty maxillary incisors were endodontically treated, received a zinc phosphate barrier and were embedded in acrylic resin until cemento-enamel junction. The specimens were distributed into five groups (n = 10) according to the number of bleaching sessions: GI, no treatment (control); GII, one session; GIII, two sessions; GIV, three sessions and GV, four sessions. The whitening gel was applied to the buccal surface of the tooth and inside the pulp chamber for three times in each session, followed by LED-laser activation. Specimens were submitted to the fracture resistance test (kN) and data were submitted to the Tukey-Kramer multiple comparisons test. Results: No significant difference (p > 0.05) was found between GI (0.71 +/- 0.30) and GII (0.65 +/- 0.13), which presented the highest strength values to fracture. Groups III (0.35 +/- 0.17), IV (0.23 +/- 0.13) and V (0.38 +/- 0.15) showed lower resistance to fracture (p < 0.01) when compared to GI and GII. Conclusions: The fracture resistance of endodontically treated teeth decreased after two sessions of bleaching with 38% hydrogen peroxide activated by LED-laser system. (c) 2008 Elsevier Ltd. All rights reserved.

Interfacial evaluation of experimentally weakened roots restored with adhesive materials and fibre posts: An SEM analysis

Objectives: To evaluate the bonding interface in experimentally weakened roots reinforced with adhesive restorative materials and quartz fibre posts, varying the light-exposure time of the composite resin used for root reinforcement. Methods: Twelve extracted human maxillary incisors teeth were used. The crowns were removed and the roots were endodontically treated. After post space preparation, the roots were assigned to four groups. The thickness of the root dentine was reduced and adhesively restored with composite resin light-activated through a translucent fibre post for either 40 s (group 1), 80 s (group 2) or 120 s (group 3). In the case of control (group 4), the roots were not weakened. One day after post cementation, the specimens were sectioned transversally in three slices and processed for scanning electron microscopic analysis to observe bonding interface formation, quality of the hybrid layer and density of resin tags using a four-step scale method. Results: Formation of a hybrid layer and resin tags were evident in all groups. There was no statistically (p > 0.05) significant difference between the regions analysed in each group (Friedman test) and between groups in each section depth (Kruskal-Wallis test). Furthermore, comparison of the flared/reinforced groups showed that the different time;; used for composite resin cure did not affect the results significantly (Kruskal-Wallis test, p = 0.2139). Conclusions: Different light-exposure times used for composite resin polymerisation during root canal reinforcement did not affect significantly the formation and quality of the dentine/adhesive/composite resin bonding interface. (C) 2008 Elsevier Ltd. All rights reserved.

Effects of light exposure time on composite resin hardness after root reinforcement using translucent fibre post

Objectives: The purpose of this in vitro study was to evaluate the Vickers hardness (VHN) of a Light Core (Bisco) composite resin after root reinforcement, according to the light exposure time, region of intracanal reinforcement and lateral distance from the light-transmitting fibre post. Methods: Forty-five 17-mm long roots were used. Twenty-four hours after obturation, the root canals were emptied to a depth of 12 mm and the root dentine was artificially flared to produce a 1 mm space between the fibre post and the canal walls. The roots were bulk restored with the composite resin, which was photoactivated through the post for 40 s (G1, control), 80 s (G2) or 120 s (G3). Twenty-four hours after post-cementation, the specimens were sectioned transversely into three slices at depths of 2, 6 and 10 mm, corresponding to the coronal, middle and apical regions of the reinforced root. Composite VHN was measured as the average of three indentations (100 g/15 s) in each region at lateral distances of 50, 200 and 350 mu m from the cement/post-interface. Results: Three-way analysis of variance (alpha = 0.05) indicated that the factors time, region and distance influenced the hardness and that the interaction time x region was statistically significant (p = 0.0193). Tukey`s test showed that the mean VHN values for G1 (76.37 +/- 8.58) and G2 (74.89 +/- 6.28) differed significantly from that for G3 (79.5 +/- 5.18). Conclusions: Composite resin hardness was significantly lower in deeper regions of root reinforcement and in lateral areas distant from the post. Overall, a light exposure time of 120 s provided higher composite hardness than the shorter times (40 and 80 s). (C) 2008 Elsevier Ltd. All rights reserved.

The role of dentists in-diagnosing osteogenesis imperfecta in patients with dentinogenesis imperfecta

Background. Osteogenesis imperfecta (OI), also known as ""brittle bone disease,"" can be difficult to diagnose in its mild form. The authors describe a clinical case of a diagnosis of dentinogenesis imperfecta (DI), In which a literature review combined with an analysis of dental alterations led to indications of OI involvement. Case Description. Since DI can be associated with OI, the authors reviewed correlated studies and obtained a new medical history from the patient. They then conducted a radiographic and clinical examination of the dentition and submitted an affected third molar to scanning electron microscopy analysis. They compared their findings with descriptions of OI type I dental alterations in the literature and confirmed their diagnosis by means of a medical evaluation. Clinical Implications. In cases in which DI is diagnosed, patients should be examined carefully and the occurrence of OI should be considered `since, in its mild form, it might be misdiagnosed.

Effect of 980-nanometer diode laser on root canal permeability after dentin treatment with different chemical solutions

This study evaluated the effect of 980-nm diode laser at different parameters on root canal dentin permeability associated with different irrigants. Seventy-five canines were sectioned at 15 mm from the apex, prepared mechanically up to #40 .02 instrument, and irrigated with 2 mL distilled water. Final irrigation (10 mL) was used as follows: (1) distilled water; (2) 1% NaOCl; (3) 17% ethylenediaminetetraacetic acid + a cationic surfactant cetyltrimethylammonium bromide (EDTAC). Laser was applied at 1.5 or 3.0 W as either continuous wave or pulsed wave (100 Hz). The teeth were then processed histochemically, the percentage of copper ion penetration into the dentin of the canal walls was counted, and the data were analyzed statistically with the Tukey-Kramer test (alpha < .01). When laser was associated with water, an increase in permeability was found, whereas permeability decreased when associated with EDTAC. Dentin permeability after laser irradiation was directly dependent on the solution used for final irrigation.