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Aims: The purpose of the present study was to evaluate the flexural strength of specimens made of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys and joined by tungsten inert gas (TIG) welding and conventional brazing. Ni-Cr and Co-Cr base metal specimens (n = 40, each) were cast and welded by TIG or brazing. The specimens were divided into six groups (2 base metals, four welded specimens). Ceramic systems were applied to the central part of all the specimens. A three-point bending test with a velocity of 0.5 mm/m was performed on the specimens up to the point of the first ceramic bond failure by measuring the flexural strength. Data were analyzed using two-way ANOVA and Bonferroni's tests. Conventional welding showed the lowest flexural strength results for both alloys, while the TIG weld and the control group presented with varying bond strengths for the alloys studied. We concluded that TIG welding was superior to the conventional welding method for both Ni-Cr and Co-Cr alloys with regard to the flexural strength of the ceramic. [ABSTRACT FROM AUTHOR]

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Purpose: To evaluate the influence of using either ultrasonic CVD (Chemical Vapor Deposition) or conventional rotary diamond tips on the adhesive strength of cingulum rest seats made of composite resin over bovine dentin. Methods: Twenty specimens were produced for each experimental group. For specimens in Group 1, the dentin was exposed with a rotary diamond tip; in Group 2 this procedure was performed using an ultrasonic CVD diamond tip. In both groups a two-step self-etching adhesive system was used, and the shape and size of the rest seats made of composite resin were standardized. The specimens were subjected to a shear assay using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by Student's t-test at the significance level of 0.05. Results: There was a statistically significant difference (P=0.028) between the means of the experimental groups: 24 kgf for Group 1 and 31 kgf for Group 2. Conclusion: Dental preparation with dentin exposure in the cingulum region by using ultrasonic CVD diamond tip showed the highest bond strength of self-etching adhesive system and composite rest seats for support of removable partial dentures. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of storage solution on bovine enamel. Forty freshly extracted bovine incisor teeth were used. The teeth were divided into four groups (n=10) following conditions, for 90 days: G1 = distilled water (control group); G2 = artificial saliva; G3 = 0,1% thymol; G4 = saline solution. After storage, the specimens were observed under a scanning electron microscope. The comparative analysis of the specimens revealed a great variation in the structure pattern of the normal enamel. The immersion in artificial saliva caused a larger precipitation of salts in the enamel surface. Increase of superficial porosity, characterized by larger amount of depressions was observed in the group of the saline solution. The specimens submerged in 0,1% thymol, revealed a flat, polished superficial aspect. The authors conclude that the storage solutions altered the dental enamel substrate. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the quality of the coronal restoration, radicular retainer, periapical status and root fillings scored on radiographic basis of endodontically treated teeth. A total of 192 periapical radiographs were randomly selected from CESUPA'S Dental School patients. According to the radiographic criteria, the technical quality was categorized as 'adequate' or 'inadequate'. The data analyzed by statistical X² test demonstrated that 53.64% had inadequate endodontic treatment; teeth with an adequate root filling were associated with a better periapical status than teeth with inadequate root filling (65.1% vs. 34.89%); teeth with adequate and inadequate coronal restorations were 48,14% and 51.85%, respectively. This difference was not statistically significant and the rate of inadequate root canal post and core was 58.33%. [ABSTRACT FROM AUTHOR]

This in vitro study evaluated the coronal seal of two temporary coronal filling materials after root canal treatment. Standardized cavities accesses were prepared in 40 intact human permanent molar teeth. They were divided into two groups consisting of 20 samples. The teeth were restored using one of the following temporary filling materials, namely: Coltosol and Vitremer. After thermocycling, the specimens were covered with cyanoacrylate, except over the coronal access. The samples were immersed in 2% methylene blue dye solution for 7 and 30 days. The teeth were sectioned and the greatest depth of dye penetration was recorded. The results showed no significantly differences between the groups (p>0,05). Under the condition of this study, the irrigants solutions during root-canal treatment influenced coronal microleakage. [ABSTRACT FROM AUTHOR]

Unlabelled: An increase in dentin roughness, associated with surface composition, contributes to bacterial adherence in recontaminations. Surface roughness is also important for micromechanical interlocking of dental materials to dentin, and understanding the characteristics of the surface is essential to obtain the adhesion of root canal sealers that have different physico-chemical characteristics., Objectives: To evaluate the effects of sodium hypochlorite (NaOCl), ethylenediaminetetraacetic (EDTA), etidronic (HEBP), and citric acid (CA) associated with different irrigation regimens on root dentin roughness., Material and Methods: Forty-five root halves of anterior teeth were used. The root parts were sectioned in thirds, embedded in acrylic resin and polished to a standard surface roughness. Initially, the samples of each third were randomly assigned into 3 groups and treated as follows: G1 - saline solution (control); G2 - 5% NaOCl+18% HEBP mixed in equal parts; and G3 - 2.5% NaOCl. After initial measuments, the G3 samples were distributed into subgroups G4, G5 and G6, which were subjected to 17% EDTA, 10% CA and 9% HEBP, respectively. Following the new measuments, these groups received a final flush with 2.5% NaOCl, producing G7, G8 and G9. The dentin surface roughness (Ra) was determined before and after treatments using a profilometer. The Wilcoxon test (α<0.05) was used to compare the values before and after treatments, and the Friedman test (α<0.05) to detect any differences among root thirds., Results: (i) NaOCl did not affect the surface roughness; (ii) there was a significant increase in roughness after the use of chelating agents (P<0.01); and (iii) only the G3 group showed a difference in surface roughness between apical third and other thirds of the teeth (P<0.0043)., Conclusion: Only the irrigation regimens that used chelating agents altered the roughness of root dentin.

The present investigation observed the sealing ability of low shrinkage composite resins in large and deep cavities, placed and photocured in one increment. Large, deep cavities (5.0 mm diameter and 2.5 mm deep) surrounded by enamel were prepared in bovine teeth, which were then divided into five groups. Groups 1, 2, 3 and 4: acid conditioning + Adper Single Bond (3M/ESPE, St Paul, MN, USA) and restoration with Aelite LS Posterior (BISCO Inc. Schaumburg, IL, USA) (G1); Filtek Z-350 (3M/ESPE,St Paul, MN, USA) (G2); Filtek Z-350 Flow (3M/ESPE, St Paul, MN, USA) (G3); Premisa (KERR Corporation, Orange, CA, USA) (G4). Group 5: Silorane Adhesive system (3M/ESPE, St Paul, MN, USA) + restoration with Filtek Low Shrinkage Posterior P90 (3M/ESPE, St Paul, MN, USA). After polymerization, the teeth were immersed in 0.5% basic fuchsine solution and immediately washed. Using the Imagetool Software, the extent of dye along the margins was calculated as a percentage of total perimeter. The restorations were then transversally sectioned and the depth of dye penetration was calculated in mm, using the same software. Kruskal-Wallis analysis for all groups showed no statistical differences for extent (p = 0.54) or depth (p = 0.8364) of dye penetration. According to this methodology, the so-called low shrinkage composite resins had the same sealing ability compared to regular and flowable nanocomposite materials.