Effectiveness of microwave irradiation on the disinfection of complete dentures

Purpose: The purpose of this study was to evaluate the effectiveness of microwave irradiation on the disinfection of simulated complete dentures. Materials and Methods: Eighty dentures were fabricated in a standardized procedure and subjected to ethylene oxide sterilization. The dentures were individually inoculated (10 7 cfu/mL) with tryptic soy broth (TSB) media containing one of the tested microorganisms (Candida albicans, Streptoccus aureus, Bacillus subtilis, and Pseudomonas aeruginosa). After 48 hours of incubation at 37°C, 40 dentures were individually immersed in 200 mL of water and submitted to microwave irradiation at 650 W for 6 minutes. Forty nonirradiated dentures were used as positive controls. Replicate aliquots (25 μL) of suspensions were plated at dilutions of 10 -3 to 10 -6 on plates of selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. TSB beakers with the microwaved dentures were incubated at 37°C for 7 more days. After incubation, the number of colony-forming units was counted and the data were statistically analyzed by Kruskal-Wallis test (α = .05). Results: No evidence of growth was observed at 48 hours for S aureus, B subtilis, and C albicans. Dentures contaminated with P aeruginosa showed small growth on 2 plates. After 7 days incubation at 37°C, no growth was visible in the TSB beakers of S aureus and C albicans. Turbidity was observed in 3 broth beakers, 2 from P aeruginosa and 1 from B subtilis. Conclusion: Microwave irradiation for 6 minutes at 650 W produced sterilization of complete dentures contaminated with S aureus and C albicans and disinfection of those contaminated with P aeruginosa and B subtilis.

Effect of disinfectants on the hardness and roughness of reline acrylic resins

Purpose: Potential effects on hardness and roughness of a necessary and effective disinfecting regimen (1% sodium hypocholorite and 4% chlorhexidine) were investigated for two hard chairside reline resins versus a heat-polymerizing denture base acrylic resin. Materials and Methods: Two standard hard chairside reliners (Kooliner and Duraliner II), one heat-treated chairside reliner (Duraliner II +10 minutes in water at 55°C), and one standard denture base material (Lucitone 550) were exposed to two disinfecting solutions (1% sodium hypochlorite; 4% chlorhexidine gluconate), and tested for two surface properties [Vickers hardness number (VHN, kg/mm2); Roughness (Ra, μm)] for different times and conditions (1 hour after production, after 48 hours at 37 ± 2°C in water, after two disinfection cycles, after 7 days in disinfection solutions, after 7 days in water only). For each experimental condition, eight specimens were made from each material. Data were analyzed by analysis of variance followed by Tukey's test, and Student's t-test (p= 0.05). Results: For Kooliner (from 6.2 ± 0.3 to 6.5 ± 0.5 VHN) and Lucitone 550 (from 16.5 ± 0.4 to 18.4 ± 1.7 VHN), no significant changes in hardness were observed either after the disinfection or after 7 days of immersion, regardless of the disinfectant solution used. For Duraliner II (from 4.0 ± 0.1 to 4.2 ± 0.1 VHN), with and without heat treatment, a small but significant increase in hardness was observed for the specimens immersed in the disinfectant solutions for 7 days (from 4.3 ± 0.2 to 4.8 ± 0.5 VHN). All materials showed no significant change in roughness (Kooliner: from 0.13 ± 0.05 to 0.48 ± 0.24 μm; Duraliner II, with and without heat treatment: from 0.15 ± 0.04 to 0.29 ± 0.07 μm; Lucitone 550: from 0.44 ± 0.19 to 0.49 ± 0.15 μm) after disinfection and after storage in water for 7 days. Conclusions: The disinfectant solutions, 1% sodium hypochlorite and 4% chlorhexidine gluconate, caused no apparent damage on hardness and roughness of the materials evaluated. Copyright © 2006 by The American College of Prosthodontists.

Effect of post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins

Introduction: Most denture base acrylic resins have polymethylmethacrylate in their composition. Several authors have discussed the polymerization process involved in converting monomer into polymer because adequate polymerization is a crucial factor in optimizing the physical properties and biocompatibility of denture base acrylic resins. To ensure the safety of these materials, in vitro cytotoxicity assays have been developed as preliminary screening tests to evaluate material biocompatibility. 3H-thymidine incorporation test, which measures the number of cells synthesizing DNA, is one of the biological assays suggested for cytotoxicity testing. Aim: The purpose of this study was to investigate, using 3H-thymidine incorporation test, the effect of microwave and water-bath post-polymerization heat treatments on the cytotoxicity of two denture base acrylic resins. Materials and Methods: Nine disc-shaped specimens (10 x 1 mm) of each denture base resin (Lucitone 550 and QC 20) were prepared according to the manufacturers' recommendations and stored in distilled water at 37°C for 48 h. The specimens were assigned to 3 groups: 1) post-polymerization in a microwave oven for 3 min at 500 W; 2) post-polymerization in water-bath at 55°C for 60 min; and 3) without post-polymerization. For preparation of eluates, 3 discs were placed into a sterile glass vial with 9 mL of Eagle's medium and incubated at 37°C for 24 h. The cytotoxic effect of the eluates was evaluated by 3H-thymidine incorporation. Results: The results showed that the components leached from the resins were cytotoxic to L929 cells, except for the specimens heat treated in water bath (p<0.05). Compared to the group with no heat treatment, water-bath decreased the cytotoxicity of the denture base acrylic resins. Conclusion: The in vitro cytotoxicity of the tested denture base materials was not influenced by microwave post-polymerization heat treatment.

Intervenções benéficas no pré-natal para prevenção da mortalidade materna

Maternal mortality rate (MM) is a health quality indicator that is directly influenced by the economic, cultural and technological level of a country. Official data of MM in Brazil, although underestimated, point to the lack of quality in pregnancy, childbirth and puerperium care services. This characteristic is common in developing countries, where poorer pregnant women as well as those facing greater difficulty to quality care access are found. Prenatal care cannot prevent major childbirth complications, which are important causes of MM; however, some interventions during the prenatal period can favor maternal prognosis and prevent MM. In this setting, this study brings a scientifically based update concerning effective interventions for maternal mortality prevention during the prenatal period. The most important strategies consist of a tripod with specific interventions related to maternal health promotion, risk prevention and assurance of nutritional support during gestation, in addition to criteria to investigate gestational risk and inclusion of the pregnant woman in the basic component of the prenatal care model. It ends with the definition of priorities in the prevention of MM related to eclampsia/preeclampsia and reinforces the importance of normalization of reference systems for obstetric emergency cases.

Bond strength of hard chairside reline resins to a rapid polymerizing denture base resin before and after thermal cycling

Purpose: This study assessed the shear bond strength of 4 hard chairside reline resins (Kooliner, Tokuso Rebase Fast, Duraliner II, Ufi Gel Hard) to a rapid polymerizing denture base resin (QC-20) processed using 2 polymerization cycles (A or B), before and after thermal cycling. Materials and Methods: Cylinders (3.5 mm x 5.0 mm) of the reline resins were bonded to cylinders of QC-20 polymerized using cycle A (boiling water-20 minutes) or B (boiling water; remove heat-20 minutes; boiling water-20 minutes). For each reline resin/polymerization cycle combination, 10 specimens (groups CAt e CBt) were thermally cycled (5 and 55°C; dwell time 30 seconds; 2,000 cycles); the other 10 were tested without thermal cycling (groups CAwt ad CBwt). Shear bond tests (0.5 mm/min) were performed on the specimens and the failure mode was assessed. Data were analyzed by 3-way ANOVA and Newman-Keuls post-hoc test (α=.05). Results: QC-20 resin demonstrated the lowest bond strengths among the reline materials (P<.05) and mainly failed cohesively. Overall, the bond strength of the hard chairside reline resins were similar (10.09±1.40 to 15.17±1.73 MPa) and most of the failures were adhesive/cohesive (mixed mode). However, Ufi Gel Hard bonded to QC-20 polymerized using cycle A and not thermally cycled showed the highest bond strength (P<.001). When Tokuso Rebase Fast and Duraliner II were bonded to QC-20 resin polymerized using cycle A, the bond strength was increased (P=.043) after thermal cycling. Conclusions: QC-20 displayed the lowest bond strength values in all groups. In general, the bond strengths of the hard chairside reline resins were comparable and not affected by polymerization cycle of QC-20 resin and thermal cycling.

Anatomia do nervo isquiático em mocós (Kerodon rupestris WIED, 1820) aplicada a clínica de animais silvestres

To know the origin of the ischiatic nerve in mocos (Kerodon rupestris Wied,1820) near by intervertebral forames and the muscling belonging to its routes were used 10 adult animals, from CEMAS-ESAM. After natural obit, they were fixed in formol (10%) and dissected to exposition and to singt of the ischiatic nerve. The results were indicated in percentage. Variations in the quantity of the lumber and sacral vertebras nere observed, five animals (50,00%) reveled seven lumbar vertebras and three sacral ones; two animals recrealed seven lumbar vertebras and four sacral ones, and two animals reveled six lumbar vertebras and three sacral ones. An animal (10,00%) revealed six lumbar vertebras and four ones. Therefore, the origin of the nerve was differentiated five animals (50,00%) had the participation of L 7,S 1,S 2; two animals (20,00%) with L 7,S 1; and a little part of S 2. Two animals (20,00%) with L 6,S 1,S 2, and an animal (10,00%) with L 6,S 1, and a little part of S 2. The last root of the ischiatic nerve in all its origins, contribute to the constitution of the first root of pudental nerve. It was verified that in all its route, the ischiatic nerves (100,00%) ceded branches to the muscles: medial gluteus, deep gluteus, superficial gluteus, emiting muscular branches to the femoral biceps or to thigh, and to the semimembranous and semi-tendinous muscles, that is continuous with a high calibre trunk, originating the fibular nerve(sideways), the tibial nerve(medial) and the lateral plantar sural cutaneous nerve (caudal).

Ectrópio palpebral: Características e relação com alterações óculo-palpebrais

Objective: To evaluate the gender and the characteristics of the ectropion carriers in our region. Methods: A retrospective study was done evolving 112 ectropion carriers. The sex, race, eyelashes alterations (trichiasis and distichiasis), anterior and posterior blepharitis, conjunctival redness, íris color and pterygium presence were evaluated. Gender data were correlated to ectropion classification (involutional, cicatricial, mechanic or paralytic) and submitted to statiscal analysis. Results: The eyelid ectropion occurred more between 71 and 80 years old.The involutional ectropion was the most frequently observed (66,07%), followed by the cicatricial, mechanic, associated types and paralytic. The majority of the patients were male (70,53%), with White skin. Trichiasis (21,42%) and distichiasis (4,46%) were associated to the ectropion eyelid and mainly in the involutional ectropion carriers. Half of the sample had blepharitis and the majority of the patients had red eye (60%) and brown iris (63,39%). Perygium was absent in the majority of the patients. Conclusion: The involutional ectropium is the most frequently observed in our region, mainly in elderly, male, White skin, brown iris and associated to trichiasis, blepharitis and red eyes.

Distortional buckling of simple lipped channel in bending results of the experimental analysis versus direct strength methods

Cold-formed steel members are subject to failure caused by buckling, normally under loads smaller than those corresponding to partial or total yielding of the cross section. The buckling of members in bending can be classified as local or global, and the occurrence of one or the other type is expected by the members' geometric characteristics and by the constraints and load conditions. One of the local instability modes that can characterize a member's failure is distortional buckling of the cross section occurring on its own plane and involving lateral displacements and rotations. This paper presents and discusses the procedures and results obtained from experimental tests of cold-formed steel members under bending. Forty-eight beams were carried out on members in simple lipped channel, in pairs, with 6-meter spans and loads applied by concentrated forces at every 1/3 of the span. The thickness, width and dimensions, of the stiffeners were chosen so that the instability by distortion buckling of the cross section was the principal failure mode expected. The experimental results are compared with the obtained results by using the direct strength method.

Molecular modeling databases: A new way in the search of protein targets for drug development

DBMODELING is a relational database of annotated comparative protein structure models and their metabolic, pathway characterization. It is focused on enzymes identified in the genomes of Mycobacterium tuberculosis and Xylella fastidiosa. The main goal of the present database is to provide structural models to be used in docking simulations and drug design. However, since the accuracy of structural models is highly dependent on sequence identity between template and target, it is necessary to make clear to the user that only models which show high structural quality should be used in such efforts. Molecular modeling of these genomes generated a database, in which all structural models were built using alignments presenting more than 30% of sequence identity, generating models with medium and high accuracy. All models in the database are publicly accessible at http://www.biocristalografia.df.ibilce.unesp.br/tools. DBMODELING user interface provides users friendly menus, so that all information can be printed in one stop from any web browser. Furthermore, DBMODELING also provides a docking interface, which allows the user to carry out geometric docking simulation, against the molecular models available in the database. There are three other important homology model databases: MODBASE, SWISSMODEL, and GTOP. The main applications of these databases are described in the present article. © 2007 Bentham Science Publishers Ltd.

Candida albicans inactivation and cell membrane integrity damage by microwave irradiation

In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K + (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (α = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P = 0.272). ES cells released significantly high protein (P < 0.001, Bradford; P = 0.005, Pyrogallol red), K+ (P < 0.001), Ca++ (P = 0.012) and DNA (P = 0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity. © 2007 The Authors.

Degree of conversion and molecular weight of one denture base and three reline resins submitted post-polymerization treatments

The effect of post-polymerization treatments (MW-microwave irradiatron and WB-water-bath) on the degree of conversion (DC) of three reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and one denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long), was evaluated by using FT-Raman spectroscopy (n = 5). The molecular weight (Mw) of the powder of all materials and of K polymerized specimens (control; MW; and WB; n = 3) was analyzed using GPC. DC data were analyzed using Kruskal-Wallis test (α = .05). For control specimens, there were no significant differences between U (68%) and LL (77%) and among LL, K (81%), and T (84%). LS (92%) had the highest DC (P<0.05). Only material K exhibited an increased DC after WB (P<0.05). All powders had Mw from 4.0 × 105 to 6.5 × 105 and narrow Mw distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with Mw similar to that of K powder.

Shear bond strength fatigue limit of rest seats made with dental restoratives

Purpose: This study compared the shear bond strength (SBS) to enamel of rest seats made with a glass-ionomer cement (Fuji IX GP Fast), a resin-modified glass-ionomer cement (Fuji II LC), and a composite resin (Z100 MP) under monotonic and cyclic loading. Materials and Methods: Rest seats were built up onto the lingual surfaces of 80 intact human mandibular incisors. Specimens (n=10) were stored in distilled water at 37°C for 30 days and subjected to shear forces in a universal testing machine (0.5 mm/min) until fracture. The SBS values were calculated (MPa) using the bonding area (9.62 mm2) delimited by adhesive tags. A staircase approach was used to determine the SBS fatigue limit of each material. Specimens were submitted to either 10,000 cycles (5 Hz) or until specimen fracture. A minimum of 15 specimens was tested for each material. Scanning electron microscopy was used to examine the mode of failure. Data were statistically analyzed with one-way ANOVA and Tukey HSD tests (α = 0.05). Results: Z100 MP yielded higher (p < 0.05) SBS (12.25 MPa) than Fuji IX GP Fast (7.21 MPa). No differences were found between Fuji II LC (10.29 MPa) and the other two materials (p > 0.05). Fuji II LC (6.54 MPa) and Z100 MP (6.26 MPa) had a similar SBS limit. Fuji IX GP Fast promoted the lowest (p < 0.05) SBS fatigue limit (2.33 MPa). All samples showed cohesive failure patterns. Conclusion: Fatigue testing can provide a better means of estimating the performance of rest seats made with dental restoratives.

The effect of water immersion on the shear bond strength between chairside reline and denture base acrylic resins: Basic science research

Purpose: The effect of water immersion on the shear bond strength (SBS) between 1 heat-polymerizing acrylic resin (Lucitone 550-L) and 4 autopolymerizing reline resins (Kooliner-K, New Truliner-N, Tokuso Rebase Fast-T, Ufi Gel Hard-U) was investigated. Specimens relined with resin L were also evaluated. Materials and Methods: One hundred sixty cylinders (20 × 20 mm) of L denture base resin were processed, and the reline resins were packed on the prepared bonding surfaces using a split-mold (3.5 × 5.0 mm). Shear tests (0.5 mm/min) were performed on the specimens (n = 8) after polymerization (control), and after immersion in water at 37°C for 7, 90, and 180 days. All fractured surfaces were examined by scanning electron microscopy (SEM) to calculate the percentage of cohesive fracture (PCF). Shear data were analyzed with 2-way ANOVA and Tukey's test; Kruskall-Wallis test was used to analyze PCF data (α = 0.05). Results: After 90 days water immersion, an increase in the mean SBS was observed for U (11.13 to 16.53 MPa; p < 0.001) and T (9.08 to 13.24 MPa, p = 0.035), whereas resin L showed a decrease (21.74 MPa to 14.96 MPa; p < 0.001). The SBS of resins K (8.44 MPa) and N (7.98 MPa) remained unaffected. The mean PCF was lower than 32.6% for K, N, and T, and higher than 65.6% for U and L. Conclusions: Long-term water immersion did not adversely affect the bond of materials K, N, T, and U and decreased the values of resin L. Materials L and U failed cohesively, and K, N, and T failed adhesively. © 2007 by The American College of Prosthodontists.

Effect of a post-polymerization treatments on the flexural strength and vickers hardness of reline and acrylic denture base resins

This study evaluated the effect of water-bath and microwave post-polymerization treatments on the flexural strength and Vickers hardness of four autopolymerizing reline resins (Duraliner II-D, Kooliner-K, Tokuso Rebase Fast-TR and Ufi Gel Hard C-UGH) and one heat-polymerized acrylic resin (Lucitone 550-L), processed using two polymerization cycles (short cycle - 90 minutes at 73°C and 100°C for 30 minutes; and long cycle - 9 hours at 71°C). For each material, thirty specimens (64 x 10 x 3.3 mm) were made and divided into 3 groups (n=10). Specimens were tested after: processing (control group); water-bath at 55°C for 10 minutes (reline materials) or 60 minutes (L); and microwave irradiation. Flexural strength tests were performed at a crosshead speed of 5 mm/min using a three-point bending device with a span of 50 mm. The flexural strengths values were calculated in MPa. One fragment of each specimen was submitted to Vickers hardness test. Data were analyzed by 2-way ANOVA followed by Tukey's HSD test (α=0.05). L microwaved specimens (short cycle) exhibited significantly higher flexural strength means than its respective control group (p<0.05). Water-bath promoted a significant increase (p<0.05) in flexural strength of K and L (long cycle). The hardness of the tested materials was not influenced by the post-polymerization treatments. Post-polymerization treatments could be used to improve the flexural strength of some materials tested.

Estudo histológico e imunoistoquímico do sistema nervoso central de cães naturalmente infectados por Leishmania (Leishmania) chagasi

The present study aimed to characterize the histopathological alterations and to detect, by immunohistochemistry, the presence of amastigote forms of Leishmania in CNS tissue of dogs with and without neurological clinical signs of the disease. Two groups of animals were used: the first was composed of 18 dogs with visceral leishmaniasis without clinical evidence of neurological involvement, and the second, composed of 21 dogs with visceral leishmaniasis and neurological symptoms. The most frequent histopathological alterations found in the CNS of dogs of both groups were neuronal degeneration with neuronophagia, gliosis, leptomeningitis, vascular congestion, presence of perivascular lymphoplasmacytic infiltrate and areas of focal microhemorrhage. Antigen labeling for whole forms of Leishmania amastigotes was not observed in any fragment of the CNS of the dogs of either groups; however, most of them presented labeling of blood vessels walls, which suggests the presence of circulating parasite antigens.