Effect of microwave disinfection on the hardness and adhesion of two resilient liners

Statement of problem. Microwave irradiation has been suggested for denture disinfection. However, the effect of this procedure on the hardness and bond strength between resilient liners and denture base acrylic resin is not known.Purpose. This study evaluated the effect of water storage time and microwave disinfection on the hardness and peel bond strength of 2 silicone resilient lining materials to a heat-polymerized acrylic resin.Material and methods. Acrylic resin (Lucitone 199) specimens (75 X 10 X 3 mm) were stored in water at 37 degrees C (2 or 30 days) before bonding (n = 160). The resilient lining materials (GC Reline Extra Soft and Dentusil) were bonded to the denture base and divided into the following 4 groups (n = 10): Tests performed immediately after bonding (control); specimens immersed in water (200 mL) and irradiated twice, with 650 W for 6 minutes; specimens irradiated daily for 7 total cycles of disinfection; specimens immersed in water (37 degrees C) for 7 days. Specimens were submitted to a 180-degree peel test (at a crosshead speed of 10 mm/min) and the failure values (MPa) and mode of failure were recorded. Pretreatment and posttreatment hardness measurements (Shore A) of the resilient materials were also performed. Three-way analysis of variance, followed by the Tukey HSD test, was performed (alpha=.05).Results. The analysis revealed that, for all conditions, the mean failure strengths of GC Reline Extra Soft (0.95-1.19 MPa) were significantly higher (P<.001) than those of Dentusil (0.45-0.50 MPa). The adhesion of the liners was not adversely affected by water storage time of Lucitone 199 or microwave disinfection. All peel test failures were cohesive. There was a small but significant difference (P<.001) between the pretreatment (34.33 Shore A) and posttreatment (38.69 Shore A) hardness measurements.Conclusion. Microwave disinfection did not compromise the hardness of either resilient liners or their adhesion to the denture base resin Lucitone 199.

Influence of thermal and mechanical stresses on the strength of intact and relined denture bases

Statement of problem. Denture bases may become increasingly weaker as a result of thermal stress and flexural cyclic loading. Information regarding this potential problem and its relationship to the denture base reline is limited.Purpose. This study evaluated the influence of thermal and mechanical stresses on the strength of intact and relined denture bases.Material and methods. Twenty-eight microwave-polymerized (Acron MC) intact denture bases were prepared in the shape of a 3-mm-thick maxillary denture. Additionally, fifty-six 2-mm-thick denture bases were relined with 1 mm of autopolymerizing resin (Tokuyama Rebase Fast II or New Truliner) (n = 28). Intact and relined specimens were divided into 4 groups (n = 7) as follows: without stress (control); a mechanical stress at 0.8 Hz for 10,000 cycles; 5000 thermal cycles between 5 degrees C and 55 degrees C; or a combination thermo-mechanical stress. The specimens were vertically loaded in compression with a rounded rod at 5 mm/min until failure, using a universal testing machine. Data on maximum fracture load (N), deflection at fracture (%), and fracture energy (N-mm) were analyzed by 2-way analysis of variance and Student-Newman-Keuls tests (alpha = .05).Results. The strength of the denture bases relined with New Truliner was not significantly affected by any of the experimental conditions, but comparing the control groups, New Truliner exhibited the lowest maximum fracture load values. The maximum fracture load of intact denture bases (P = .002) and those relined with Tokuyama Rebase Fast II (P = .01) showed a significant decrease after thermal stress. Additionally, cyclic loading significantly decreased the maximum fracture load (P < .001), deflection at fracture (P = .025), and fracture energy (P < .001) of intact denture bases and those relined with Tokuyama Rebase (P values of .002, .039, and .001, respectively).Conclusion. Thermal and mechanical stresses exert deleterious effects on the strength of intact and/or relined denture bases, which vary according to the relining material used.

Comparison of the occlusal vertical dimension after processing complete dentures made with lingualized balanced occlusion and conventional balanced occlusion

Statement of problem. An increase in occlusal vertical dimension (OVD) may occur after processing complete dentures. Although many factors that generate this change are known, no information is available in the dental literature regarding the effect that the occlusal scheme may have on the change in OVD.Purpose. This in vitro study compared the increase in OVD, after processing, between complete dentures with teeth arranged in lingualized balanced occlusion and conventional balanced occlusion.Material and methods. Thirty sets of complete dentures were evaluated as follows: 15 sets of complete dentures were arranged in conventional balanced occlusion (control) and 15 sets of complete dentures were arranged in lingualized balanced occlusion. All dentures were compression molded with a long polymerization cycle. The occlusal vertical dimension was measured with a micrometer (mm) before and after processing each set of dentures. Data were analyzed using an independent t test (alpha=.05).Results. The mean increase in the OVD, after processing, was 0.87 +/- 0.21 mm for the control group and 0.90 +/- 0.27 mm for the experimental group. There was no significant difference between the groups.Conclusion. After processing, dentures set in lingualized balanced occlusion showed an increase in OVD similar to those set in conventional balanced occlusion.

Natural history of the South American water snake Helicops leopardinus (Colubridae : Hydropsini) in the pantanal, Central Brazil

The South American water snake Helicops leopardinus is very abundant in the Pantanal wetlands of Central Brazil. We studied the biology of this species based on specimens collected by local workers in the Paraguay River. Females attained greater body lengths and had larger heads than males, but the latter had longer tails. Helicops leopardinus fed on a wide variety of fishes (70% of the total prey items) and frogs, with fishes of the order Gymnotiformes (33.34%) and frogs of the family Hylidae (23.34%) representing the most common prey items. There was relatively lows diet overlap between the sexes and between juveniles and adults. Mean litter size was 6.6 and ranged from 4-11. The reproductive cycle was seasonal, with birth occurring late in the wet season (simultaneous with the flooding of the Paraguay River), facilitating dispersal of young snakes by floating vegetation. Floating vegetation may be a critical habitat for H. leopardinus, and management plans for their maintenance need to be developed.

A New Species of Meliosma (Sabiaceae) from Southeastern Brazil and Notes on the Genus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The taxonomic status of Leptodactylus geminus Barrio, 1973

The advertisement calls of Leptodactylus geminus, Leptodactylus gracilis, Leptodactylus plaumanni, and Leptodactylus fuscus are analyzed and compared with published reports. Based on calling data and examination of type material, Leptodactylus geminus is synonymized with L, plaumanni. To differentiate between the sibling species L. gracilis and L. plaumanni, fieldwork is needed, including recording of advertisement calls. Reliable identification of red specimens is not possible based on morphology and coloration alone.

Social interactions in Hypsiboas albomarginatus (Anura : Hylidae) and the significance of acoustic and visual signals

Social behavior of Hypsiboas albomarginatus was studied in the Atlantic rain forest, Municipality of Ubatuba, in the north coast of the State of São Paulo, southeastern Brazil. Vocalizations of H. albomarginatus are described, including contexts in which they were emitted and temporal and spectral parameters differentiating advertisement from aggressive calls. Dominant call frequency was inversely correlated with male length and body mass but not with environmental temperature. Number of pulses per note was not correlated with any variable, and advertisement call amplitude was influenced by temperature and time. During chorus aggregation, males interacted acoustically by emitting advertisement calls in antiphony, or by emitting aggressive calls. Some disputes among males culminated in physical combat; males performed kicks and slaps on rivals' heads, in an apparent attempt to dislodge rivals from perches. Visual signals were also displayed during conflicts between males, contributing to an escalation of aggressive behavior. Visual signals were not recorded during courtship between males and females but may help in the accurate localization of the signaling male during aggressive interactions.

A Cytotaxonomic Survey of the Genus Melanophryniscus Gallardo, 1961 (Anura: Bufonidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Osteology and Intraspecific Variation of Leptodactylus podicipinus (Anura: Leptodactylidae), with Comments on the Relationship between Osteology and Reproductive Modes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Geographic variation in cranial shape in the Pumpkin Toadlet (Brachycephalus ephippium): A geometric analysis

The description of patterns of variation in any character system within well-defined species is fundamental for understanding lineage diversification and the identification of geographic units that represent opportunities for sustained evolutionary divergence. In this paper, we analyze intraspecific variation in cranial shape in the Pumpkin Toadlet, Brachycephalus ephippium-a miniaturized species composed of isolated populations on the slopes of the mountain ranges of southeastern Brazil. Shape variables were derived using geometric-statistical methods that describe shape change as localized deformations in a spatial framework defined by anatomical landmarks in the cranium of B. ephippium. By statistically weighting differences between landmarks that are not close together (changes at larger geometric scale), cranial variation among geographic samples of B. ephippium appears continuous with no obvious gaps. This pattern of variation is caused by a confounding effect between within-sample allometry and among-sample shape differences. In contrast, by statistically weighting differences between landmarks that are at close spacing (changes at smaller geometric scale), differences in shape within- and among-sample variation are not confounded, and a marked geographic differentiation among population samples of B. ephippium emerges. The observed pattern of geographic differentiation in cranial shape apparently cannot be explained as isolation-by-distance. This study provides the first evidence that the detection of morphological variation or lack thereof, that is, morphological conservatism, may be conditional on the scale of measurement of variation in shape within the methodological formalism of geometric morphometrics.

Geographic Distribution and Morphological Variation of Striped and Nonstriped Populations of the Brazilian Atlantic Forest Treefrog Hypsiboas bischoffi (Anura: Hylidae)

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

Description of the Tadpole of Hylodes magalhaesi (Bokermann, 1964) (Anura: Hylodidae)

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

Oral Exfoliative Cytology for the Diagnosis of Paracoccidioidomycosis in a Patient with Human Immunodeficiency Virus A Case Report

BackgroundParacoccidioidomycosis is not the most common fungal disease in patients infected with human immunodeficiency virus (HIV), except for endemic regions in Latin America countriesCaseA 33-year-old man with HIV presented with mulberry-like lesions on the palate The diagnosis was made by exfoliative cytology and Papanicolaou staining Microscopic analysis revealed fungal structures with birefringent walls and exosporulation conferring an airplane radial motor appearance, or even bowel-like or goblet-like forms compatible with Paracoccidioides brasiliensisConclusionThis process spares the immunosuppressed patient from under going invasive biopsy procedures (Acta Cytol 2010,54 1127-1129)

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.