Presence and morphology of the molar tubercle according to dentition, hemi-arch and sex

The purpose of this study was to assess the presence and the degree of expression of the molar tubercle according to sex, dentition and hemi-arches. Study casts of 126 patients were assessed, and those were under orthodontic treatment at the University of Franca, UNIFRAN; they were from both sexs, from 4 to 13 years old. The upper second primary molars and the upper first permanent molars, from both sides, were evaluated regarding the presence and the degree of expression of the molar tubercle. For an association study, the qui-square test was utilized. The concordance about the presence or absence of the molar tubercle according to dentition, hemi-arch and sex, was estimated by the Kappa Statistics. There was a sexual dimorphism concerning the presence/absence of the molar tubercle (p=0.009), however there was no significant association between the degree of expression of the tubercle and the sex (p=0.791). The molar tubercle was more frequently observed in the male sex, in upper second primary molars and in the form of depression. There was a significant and "moderate" concordance between the left and right sides in primary dentition (k=0.596), there was a "good" concordance in permanent dentition (k=0.708) and a "weak" and significant concordance between the presence of the molar tubercle and dentition (k=0.207).

The use of calcium hydroxide and mineral trioxide aggregate on apexification of a replanted tooth: a case report

To report the outcome of the endodontic treatment of a reimplanted central maxillary incisor with open apex after 8 years and 7 months of follow-up.This case report presents the treatment of a right central maxillary incisor of an 8-year old white male patient with history of traumatic avulsion and immediate replantation. The endodontic therapy consisted of periodical changes of calcium hydroxide dressing and a definitive root canal filling with mineral trioxide aggregate (MTA). The treatment was successful without pathologies up to 7 years of follow-up. After the institution of orthodontic treatment a localized and late root resorption was noticed at the last radiographic examination (8 years and 7 months postoperative follow-up). Moreover, the use of MTA promoted a mild crown grey discoloration.

Morphometrical analysis of cleaning capacity of a hybrid instrumentation in mesial flattened root canals

The cleaning capacity of hybrid and rotary instrumentation techniques in mesial flattened canals of mandibular first molars was evaluated by morphometrical analysis in this study. Twenty human mandibular first molars were randomly assigned into two groups, according to instrumentation technique, as follows: group 1, instrumentation with ProTaper Starter Kit (Dentsply/Maillefer) rotary system; group 2, manual instrumentation using K files (Dentsply/Maillefer) by crown-down technique in middle and apical thirds, cervical preparation with Gates-Glidden #1 and #2 (Dentsply/Maillefer) burs, and to finalise the preparation, ProTaper F2 and F3 rotary files. Serial transverse cross-sections (5 mu m) of the apical third, stained with hematoxylin and eosin, were analysed at 100 x original magnification. The images were submitted to morphometrical analysis with an integration grid to determine the percentage of root canal area with debris. Statiscal analysis (t-Student, P < 0.05) showed significant difference between the techniques (P < 0.05), although neither completely cleaned the root canal.

Persistence of endodontic methacrylate-based cement residues on dentin adhesive surface treated with different chemical removal protocols

The aim of this study was to evaluate the persistence of methacrylate-based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin-based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G199.5% ethanol and G2acetone, without previous use of dentin adhesive; G399.5% ethanol and G4acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500x magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to KruskalWallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues.

In Vitro Study of Fracture Load and Fracture Pattern of Ceramic Crowns: A Finite Element and Fractography Analysis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Resin Cement System and Root Region on the Push-out Bond Strength of a Translucent Fiber Post

Objectives: This study evaluated the bond strength of luting systems for bonding glass fiber posts to root canal dentin. The hypothesis tested was that there are no differences in bond strength of glass fiber posts luted with different cement systems.Methods: Forty bovine incisors were randomly assigned to five different resin cement groups (n=8). After endodontic treatment and crown removal, translucent glass fiber posts were bonded into the root canal using five different luting protocols (self-cured cement and etch-and-rinse adhesive system; dual-cured cement and etch-and-rinse adhesive system; self-cured cement and self-etch adhesive system; dual-cured cement and self-etch adhesive system; and dual-cured self-adhesive cement). Push-out bond strength was evaluated at three different radicular levels: cervical, middle, and apical. The interface between resinous cement and the post was observed using a stereoscopic microscope.Results: Analysis of variance showed a statistically significant difference among the cements (p<0.05) and the root canal thirds (p<0.05). The self-adhesive resinous cement had lower values of retention.Conclusions: The resin cements used with etch-and-rinse and self-etch adhesive systems seem to be adequate for glass fiber post cementation.

Evaluation of three enrichment broths and five plating media for Salmonella detection in poultry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Growth and reproductive dynamics of the South American red shrimp, Pleoticus muelleri (Crustacea: Solenoceridae), from the southeastern coast of Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Repeated unrewarded scent exposure influences the food choice of stingless bee foragers, Melipona scutellaris

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Morphology, development and homologies of the perianth and floral nectaries in Croton and Astraea (Euphorbiaceae-Malpighiales)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dentine microhardness after different methods for detection and removal of carious dentine tissue

There are several methods for identifying carious dentinal tissue aiming to avoid removal of healthy dentinal tissue. Objectives: The purpose of this study was to test different methods for the detection of carious dentinal tissue regarding the amount of carious tissue removed and the remaining dentin microhardness after caries removal. Material and methods: The dentin surfaces of 20 bovine teeth were exposed and half of the surface was protected with nail polish. Cariogenic challenge was performed by immersion in a demineralizing solution for 14 days. After transverse cross-section of the crown, the specimens were divided into four groups (n=10), according to the method used to identify and remove the carious tissue: "Papacarie", Caries-detector dye, DIAGNOdent and Tactile method. After caries removal, the cross-sectional surface was included in acrylic resin and polished. In a microhardness tester, the removed dentin thickness and the Vickers microhardness of the following regions were evaluated: remaining dentin after caries removal and superficial and deep healthy dentin. Results: ANOVA and Tukey's test (alpha=0.05) were performed, except for DIAGNOdent, which did not detect the presence of caries. Results for removed dentin thickness were: "Papacarie" (424.7 +/- 105.0; a), Caries-detector dye (370.5 +/- 78.3; ab), Tactile method (322.8 +/- 51.5; bc). Results for the remaining dentin microhardness were: "Papacarie" (42.2 +/- 10.5; bc), Caries-detector dye (44.6 +/- 11.8; bc), Tactile method (24.3 +/- 9.0; d). Conclusions: DIAGNOdent did not detect the presence of carious tissue; Tactile method and "Papacarie" resulted in the least and the most dentinal thickness removal, respectively; Tactile method differed significantly from "Papacarie" and Caries-detector dye in terms of the remaining dentin microhardness, and Tactile method was the one which presented the lowest microhardness values.

Effects of cement thickness and bonding on the failure loads of CAD/CAM ceramic crowns: Multi-physics FEA modeling and monotonic testing

Objective. To determine the influence of cement thickness and ceramic/cement bonding on stresses and failure of CAD/CAM crowns, using both multi-physics finite element analysis and monotonic testing.Methods. Axially symmetric FEA models were created for stress analysis of a stylized monolithic crown having resin cement thicknesses from 50 to 500 mu m under occlusal loading. Ceramic-cement interface was modeled as bonded or not-bonded (cement-dentin as bonded). Cement polymerization shrinkage was simulated as a thermal contraction. Loads necessary to reach stresses for radial cracking from the intaglio surface were calculated by FEA. Experimentally, feldspathic CAD/CAM crowns based on the FEA model were machined having different occlusal cementation spaces, etched and cemented to dentin analogs. Non-bonding of etched ceramic was achieved using a thin layer of poly(dimethylsiloxane). Crowns were loaded to failure at 5 N/s, with radial cracks detected acoustically.Results. Failure loads depended on the bonding condition and the cement thickness for both FEA and physical testing. Average fracture loads for bonded crowns were: 673.5 N at 50 mu m cement and 300.6 N at 500 mu m. FEA stresses due to polymerization shrinkage increased with the cement thickness overwhelming the protective effect of bonding, as was also seen experimentally. At 50 mu m cement thickness, bonded crowns withstood at least twice the load before failure than non-bonded crowns.Significance. Occlusal "fit" can have structural implications for CAD/CAM crowns; pre-cementation spaces around 50-100 mu m being recommended from this study. Bonding benefits were lost at thickness approaching 450-500 mu m due to polymerization shrinkage stresses. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Marginal and Internal Discrepancies Related to Margin Design of Ceramic Crowns Fabricated by a CAD/CAM System

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The interaction between atoms of Au and Cu with clean Si(111) surface: A study combining synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesions

Objective. To evaluate the healing of experimentally induced chronic periapical lesions in dogs at 30, 75, and 120 days after root canal instrumentation with rotary NiTi files or manual K-files, with or without a calcium hydroxide/1% chlorhexidine paste intracanal dressing.Study design. The second, third, and fourth mandibular premolars and the second and third maxillary premolars of 5 dogs (12 to 18 months of age, weighing 8 to 15 kg) were selected for treatment (a total of 82 root canals). After pulp removal, the root canals were left exposed to the oral cavity for 7 days to allow microbial contamination, after which the root canals were sealed with ZOE cement until periapical lesions were confirmed with radiography. Group I and II teeth were instrumented with manual K-files using the crown-down technique. In group III and IV teeth, NiTi rotary files were used. The apical delta was perforated by using #20 to #30 K-files at the length of the tooth, thus creating a standardized apical opening. The apical stop was enlarged to size 70, with 2.5% sodium hypochlorite irrigation at each file change. Teeth in groups II and IV were dressed with calcium hydroxide (Ca(OH)(2))/1% chlorhexidine (CHX) paste for 15 days before root filling. Group I and III teeth did not receive an intracanal dressing. The access openings of the teeth were permanently restored with silver amalgam condensed on a glass ionomer cement base. Pairs of standardized periapical radiographs were taken at the beginning of the treatment (0 days) and at 30, 75, and 120 days after filling.Results. There was no significant difference in the rate of radiographic healing of the periapical lesions between manual and rotary instrumentation. Radiographs taken at 120 days showed that the treatment with Ca(OH)(2)/1% CHX paste resulted in a significant reduction in mean size of the periapical lesions in comparison to single-session treatment. These findings were also true for histologic observations.Conclusion. The findings support the hypothesis that, regardless of the instrumentation technique (manual or rotary), the use of an intracanal dressing is important in the endodontic treatment of dog's teeth with experimentally induced chronic periapical lesions.