Experimental infection of pregnant queens with two major Brazilian clonal lineages of Toxoplasma gondii

Toxoplasma gondii isolates from Brazil are biologically and genetically different from European and North America isolates. Recently, four genotypes were considered the common clonal lineages in Brazil and were designated as types BrI, BrII, BrIII, and BrIV. The pathogenicity of two major Brazilian lineages was investigated after oral inoculation of queens in the middle third of their pregnancies with T. gondii cysts. Twelve pregnant queens without T. gondii antibodies were distributed in group A (infected with a type BrI isolate); group 2 (infected with type BrIII isolate), and group 3 (non-infected control). Infection with type BrI isolate caused toxoplasmosis manifestations and abortion from one litter. Toxoplasmosis manifestations besides premature stillbirth of one litter were observed in queens infected with type BrIII isolate. Indirect fluorescence antibody test showed T. gondii antibodies in all eight infected queens at 30 days after inoculation. In two 10-day-old kittens of the same litter (group 1), titers of 16 and 64 were detected. At the same time, titers of 16, 32, and 32 were detected in three kittens from the same litter (group 2). Experimental infection with tissue cysts from a type BrI and type BrIII isolates of T. gondii developed similar reproductive disturbance in primary infected pregnant queens.

Performance of techniques used for re-attachment of endodontically treated crown fractured teeth

Objectives: The aim of this study was to compare the fracture strength of three techniques used to re-attach tooth fragments in sound and endodontically treated fractured teeth with or without fiber post placement. Material and methods: Ninety human lower incisors were randomly divided into three groups of 30 teeth each. In group A teeth were not subjected to endodontic treatment; while teeth from groups B and C were endodontically treated and the pulp chamber restored with a composite resin. All teeth were fractured by an axial load applied to the buccal area in order to obtain tooth fragments. Teeth from each group were then divided into three subgroups, according to the re-attachment technique: bonded-only, buccal-chamfer and circumferential chamfer. Before the re-attachment procedures, fiber posts were placed in teeth from group C using dual cure resin luting cement (Duo-Link). All teeth (groups A-C) had the fragments re-attached using a same dual cure resin luting cement. in the bonded-only group, no additional preparation was made. After re-attachment of the fragment, teeth from groups buccal and circumferential chamfer groups had a 1.0 mm depth chamfer placed in the fracture line either on buccal surfaceor along the buccal and lingual surfaces, respectively. increments of microhybid composite resin (Tetric Ceram) were used in subgroups buccal chamfer and circumferential chamfer to restore the chamfer. The specimens were loaded until fracture in the same pre-determined area. The force required to detach each fragment was recorded and the data was subjected to a three-way analysis of variance where factors Group and Re-attachment technique are independent measures and Time of fracture is a repeated measure factor (first and second) and Tukey`s test (alpha = 0.05). Results: The main factors Re-attachment technique (p = 0.04) and Time of fracture (p = 0.02) were statistically significant. The buccal and circumferential chamfer techniques were statistically similar (p > 0.05) and superior to the bonded-only group (p < 0.05). The first time of fracture was statistically superior to second time of fracture (p < 0.001). Conclusions: The use of fiber post is not necessary for the reinforcement of the tooth structure in re-attachment of endodontically treated teeth. When bonding a fractured fragment, the buccal or circumferential re-attachment techniques should be preferable in comparison with the simple re-attachment without any additional preparation. None of the techniques used for re-attachment restored the fracture strength of the intact teeth. (C) 2008 Elsevier Ltd. All rights reserved.

Periodontal attachment loss in an untreated isolated population of Brazil

Background: The aim of this study was to assess the prevalence, extent, and severity of clinical attachment loss (CAL) and to investigate the association of demographic, socioeconomic, and behavioral risk indicators with CAL in an untreated isolated population in Brazil. Methods: All subjects aged >= 12 years were identified by a census. Participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Results: Among the 214 subjects who were interviewed and examined clinically, CAL >= 5 mm in at least one site was observed in 8% of the 12- to 19-year-olds and in all dentate subjects >= 50 years of age; the age-dependent prevalence of CAL >= 7 mm in at least one site ranged from 5% among 12- to 19-year-olds to 83% among subjects >= 50 years old. Multivariate analysis identified plaque (odds ratio [OR] = 2.8), supragingival calculus (OR = 2.9 to 10.6), age >= 30 years (OR = 11.4), and smoking (OR = 2.4) as risk indicators for CAL >= 5 mm and smoking (OR = 8.2) as a risk indicator for CAL >= 7 mm. Conclusions: CAL is highly prevalent in this isolated population. The high occurrence of CAL in young age groups and the confirmation of traditional risk indicators for CAL in this study suggest that other factors, such as host susceptibility, may be needed to explain the high levels of CAL found. Age and behavioral factors were risk indicators associated significantly with the CAL found in this population and may be useful indicators of high-risk subjects for periodontal diseases.

Tooth loss prevalence and risk indicators in an isolated population of Brazil

Objective. The aim of this study was to assess the prevalence, extent, and risk indicators of tooth loss in an isolated population of Brazil. Material and methods. Two-hundred-and-forty-two subjects, ranging in age from 14 to 82 years (mean 36.2 years), were identified by census in an isolated population of Brazil. All consenting subjects received a full-mouth clinical (DFT index and information about missing teeth) and periodontal examination of 6 sites per tooth. Furthermore, they were interviewed using a structured written questionnaire in order to gather information about demographic, environmental, and biological variables. Results. Of the 200 subjects (80% response rate), 19 (9.5%) were edentulous, 90% had lost at least one tooth, and 39% had lost more than 8 teeth. The mean number of teeth lost was 9.5 (95% CI = 8.2-10.8). First mandibular molars were the most commonly missing teeth. In a multiple logistic regression analysis based on a theoretical hierarchical model of tooth loss, having more than 8 teeth lost was strongly associated with adult age (OR = 18.3-17.3, 95% CIs = 4.8-69.7 and 4.0-75.1) and female gender (OR = 5.9, 95% CI = 1.9-18.2) in the final model. Conclusions. Tooth loss was highly prevalent and extensive in this isolated population. Demographic and behavioral factors played an important role in tooth loss prevalence in this population.

Risk indicators for increased probing depth in an isolated population in Brazil

Background: The aim of this study was to assess the prevalence, extent, and severity of probing depth (PD) and to investigate the associations between demographic, socioeconomic, and behavioral risk indicators and PD in a periodontally untreated and isolated population in Brazil. Methods: The target population consisted of all individuals aged >= 12 years as identified by a census. Consenting participants were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured written questionnaire. Results: Among the 214 subjects who were interviewed and clinically examined, PD >= 4 mm was observed in 54% to 83% of the subjects, depending on age, whereas the age-dependent prevalence of PD :6 mm ranged from 5% among 12- to 19-year-olds to 50% among 40- to 49-year-olds, decreasing to 40% among subjects >= 50 years of age. Multivariate analyses identified supragingival calculus (odds ratio [OR] = 5.4 to 10.3; 95% confidence intervals [CIs]: 2.5 to 11.6 and 4.0 to 26.2 for 20% to 50% and > 50% of the sites, respectively) as a risk indicator for PD A mm, whereas age :40 years (OR = 9.0; 95% CI: 1.7 to 48.5), being a moderate/heavy smoker (OR = 3.7; 95% CI: 1.4 to 10. 1), and having supragingival calculus in 20% to 50% of sites (OR = 6.8; 95% CI: 1.4 to 32.4) or in >50% of sites (OR = 15.3; 95% CI: 3.2 to 73.6) were risk indicators for PD >= 6 mm. Having undergone urgency dental treatment was a protective factor for PD A and >= 6 mm (OR = 0.4; 95% CI: 0.2 to 0.8). Conclusions: Increased PD is highly prevalent in this isolated population. Behavioral factors played a significant role as risk indicators for increased PD in this isolated population.

Clinical versus laboratory adhesive performance to wet and dry demineralized primary dentin

Purpose: To evaluate the influence of dentin moisture on bond strengths of an etch-and-rinse bonding agent to primary dentin clinically and in the laboratory. Methods: The sample consisted of two groups of 20 caries-free primary second molars: molars in exfoliation period (clinical group) and extracted molars (laboratory group). Class I cavities were prepared in all specimens leaving a flat dentin surface on the pulpal floor. A two-step etch-and-rinse adhesive was vigorously rubbed on either dry (n= 5) or wet demineralized dentin (n= 5) under clinical or laboratory conditions. After restorative procedures, the teeth from the clinical group were extracted after 20 minutes. All samples were processed and underwent microtensile bond strength test and silver nitrate uptake evaluation under scanning electron microscopy. Results: Statistically higher bond strength values were observed when the bonding was performed under laboratory conditions and on a wet demineralized dentin. Most of the failures were adhesive and mixed irrespective of the experimental condition. Silver nitrate uptake occurred in all groups irrespective of the experimental condition. Resin-dentin bond strengths produced in the laboratory in primary teeth may overestimate those produced under clinical circumstances. (Am J Dent 2011;24:221-225).

Effects of adhesive temperature on the early and 6-month dentin bonding

Objectives: The aim of this study was to test the effect of adhesive temperature on the bond strength to dentin (mu TBS) and silver nitrate uptake (SNU) of an ethanol/water (Adper Single Bond 2 [SB]) and an acetone-based (Prime&Bond 2.1 [PB]) etch-and-rinse adhesive system. Methods: The bottles of each adhesive were kept in various temperatures (5 degrees C, 20 degrees C, 37 degrees C and 50 degrees C) for 1 h previously to its application in the occlusal demineralized dentin of 40 molars. Bonded sticks (0.8 mm(2)) were tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6 M) of water storage. Two bonded sticks from each hemi-tooth were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measures ANOVA and Tukey`s test (alpha = 0.05). Results: No significant difference in mu TBS was detected for both adhesives at 5 degrees C and 20 degrees C. The highest bond strength for PB was observed in the 37 degrees C group while for SB it was in the 50 degrees C. Significant reductions of bond strengths were observed for PB at 37 degrees C and SB at 50 degrees C after 6 M of water storage. Silver nitrate deposition was seen in all hybrid layers, irrespective of the group. Lower silver nitrate deposition (water trees) in the adhesive layer was seen for PB and SB at higher temperatures. Conclusions: The heating or refrigeration of the adhesives did not improve their resin-dentin bond resistance to water degradation over time. (C) 2009 Elsevier Ltd. All rights reserved.

Can the durability of one-step self-etch adhesives be improved by double application or by an extra layer of hydrophobic resin?

Objectives: This study evaluated the immediate and 6-month resin-dentin mu-bond strength (mu TBS) of one-step self-etch systems (Adper Prompt L-Pop [AD] 3M ESPE; Xeno III [XE] Dentsply De Trey; iBond [iB] Heraeus Kulzer) under different application modes. Materials and methods: Dentin oclusal surfaces were exposed by grinding with 600-grit SiC paper. The adhesives were applied according to the manufacturer`s directions [MD], or with double application of the adhesive layer [DA] or following the manufacturer`s directions plus a hydrophobic resin layer coating [HL]. After applying the adhesive resins, composite crowns were built up incrementally. After 24-h water storage, the specimens were serially sectioned in ""x"" and ""y"" directions to obtain bonded sticks of about 0.8 mm 2 to be tested immediately [IM] or after 6 months of water storage [6M] at a crosshead speed of 0.5 mm/min. The data from each adhesive was analyzed by a two-way repeated measures ANOVA (mode of application vs. storage time) and Tukey`s test (alpha = 0.05). Results: The adhesives performed differently according to the application mode. The DA and HL either improved the immediate performance of the adhesive or did not differ from the MD. The resin-dentin bond strength values observed after 6 months were higher when a hydrophobic resin coat was used than compared to those values observed under the manufacturer`s directions. Conclusions: The double application of one-step self-etch system can be safety performed however the application of an additional hydrophobic resin layer can improve the immediate resin-dentin bonds and reduce the degradation of resin bonds over time. (c) 2008 Elsevier Ltd. All rights reserved.

Effect of prolonged application times on the durability of resin-dentin bonds

Objectives. To examine the effect of prolonged application time on the early and 3-year resin-dentin microtensile bond strength. Methods. Water/ethanol (Single Bond [SB]) and acetone-based systems (One Step [OS]) were employed. A flat superficial dentin surface was exposed in third human molars by wet abrasion. The adhesives were applied to a delimited area of 52 mm(2) on wet surfaces, for 40, 90, 150 and 300s. Four teeth were assigned for each experimental condition. Composite build-ups were constructed incrementally After water storage at 37 degrees C for 24 h, teeth were sectioned to obtain sticks with cross-sectional areas of 0.8 mm(2) to be tested in tension (0.5 mm/min) either immediately (IM) or after 3 years (3Y) of water storage. The microtensile bond strength (mu TBS) values were analyzed by two way repeated measures ANOVA and Tukey`s test (alpha = 0.05). Results. The 90- and 150-s groups achieved the highest IM mu TBS for OS (p < 0.01). For SB, the highest IM mu TBS values were observed after 300-s application (p < 0.01). Significant decreases in mu TBS were observed for OS in the 40- and 90-s groups after 3Y, except for the 150-s group. With regard to SB, after 3Y significant drops in mu TBS values were observed for the 40- and 150-s groups, except for the 300-s group. Significance. Prolonged application times can increase the immediate LTBS of two-step etch-and-rinse adhesive systems and make the adhesive layer more stable over time. (c) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Composite pre-heating: Effects on marginal adaptation, degree of conversion and mechanical properties

Objectives. This study evaluated the effect of composite pre-polymerization temperature and energy density on the marginal adaptation (MA), degree of conversion (DC), flexural strength (FS), and polymer cross-linking (PCL) of a resin composite (Filtek Z350, 3M/ESPE). Methods. For MA, class V cavities (4mmx2mmx2mm) were prepared in 40 bovine incisors. The adhesive system Adper Single Bond 2 (3M/ESPE) was applied. Before being placed in the cavities, the resin composite was either kept at room-temperature (25 degrees C) or previously pre-heated to 68 degrees C in the Calset (TM) device (AdDent Inc., Danbury, CT, USA). The composite was then light polymerized for 20 or 40s at 600mW/cm(2) (12 or 24 J/cm(2), respectively). The percentage of gaps was analyzed by scanning electron microscopy, after sectioning the restorations and preparing epoxy resin replicas. DC (n = 3) was obtained by FT-Raman spectroscopy on irradiated and non-irradiated composite surfaces. FS (n = 10) was measured by the three-point-bending test. KHN (n = 6) was measured after 24h dry storage and again after immersion in 100% ethanol solution for 24 h, to calculate PCL density. Data were analyzed by appropriate statistical analyses. Results. The pre-heated composite showed better MA than the room-temperature groups. A higher number of gaps were observed in the room-temperature groups, irrespective of the energy density, mainly in the axial wall (p < 0.05). Composite pre-heating and energy density did not affect the DC, FS and PCL (p > 0.05). Significance. Pre-heating the composite prior to light polymerization similar in a clinical situation did not alter the mechanical properties and monomer conversion of the composite, but provided enhanced composite adaptation to cavity walls. (C) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of argon purity on mechanical properties, microstructure and fracture mode of commercially pure (cp) Ti and Ti-6Al-4V alloys for ceramometal dental prostheses

Provision of an inert gas atmosphere with high-purity argon gas is recommended for preventing titanium castings from contamination although the effects of the level of argon purity on the mechanical properties and the clinical performance of Ti castings have not yet been investigated. The purpose of this study was to evaluate the effect of argon purity on the mechanical properties and microstructure of commercially pure (cp) Ti and Ti-6Al-4V alloys. The castings were made using either high-purity and/or industrial argon gas. The ultimate tensile strength (UTS), proportional limit (PL), elongation (EL) and microhardness (VHN) at different depths were evaluated. The microstructure of the alloys was also revealed and the fracture mode was analyzed by scanning electron microscopy. The data from the mechanical tests and hardness were subjected to a two-and three-way ANOVA and Tukey`s test (alpha = 0.05). The mean values of mechanical properties were not affected by the argon gas purity. Higher UTS, PL and VHN, and lower EL were observed for Ti-6Al-4V. The microhardness was not influenced by the argon gas purity. The industrial argon gas can be used to cast cp Ti and Ti-6Al-4V.

A 24-month randomized clinical trial of a two- and three-step etch-and-rinse technique

Purpose This 24-month randomized paired tooth clinical study evaluated the performance of All Bond 3 used in the simplified (2-step) and full (3-step) versions Methods 33 patients, with at least two similar sized non-carious cervical lesions participated in this study A total of 66 restorations were placed, half using the 2-step All Bond 3 (AB3-2) and the other half using 3-step All Bond 3 (AB3-3) The restorations were placed incrementally using the composite resin Aelite The restorations were evaluated at baseline and after 6, 12 and 24 months following the modified USPHS criteria Statistical differences between the adhesive were tested using with McNemar`s test and clinical performance over time for each material with the Fisher`s exact test (alpha= 0 05) Results After 24 months, six AB3-2 and four AB3-3 were rated as bravo for marginal discoloration but did not differ from each other significantly (P> 0 05) The retention rates at 24 months of AB3-2 and AB3-3 were 90 9% and 97 0%, respectively (P> 0 05) (Am J Dent 2010,23 231-236)

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)

Assessment of the biocompatibility of Epiphany root canal sealer in rat subcutaneous tissues

Objective. The aim of this study was to evaluate the biocompatibility of the root canal sealer Epiphany in rat subcutaneous tissues. Study design. Polyethylene tubes were filled with the sealer (I: Epiphany; II: photoactivated Epiphany; III: Epiphany associated with self-etch primer; IV: photoactivated Epiphany associated with primer; and V: control group) and later implanted into 4 different regions of the dorsum of 15 adult male rats (Rattus novergicus, Albinus Wistar). After 7, 21, and 42 days, 5 animals were killed, obtaining 4 samples per group, in addition to the control group, at each analyzed time. Results. In all periods, Epiphany induced a mild inflammatory reaction. However, in group II, in which the primer was not used, extensive necrosis and a moderate to intense inflammatory reaction were observed, mainly after 7 and 21 days. Conclusion. Epiphany sealer appears biocompatible when tested on rat subcutaneous tissues.

Atmospheric versus vegetation controls of Amazonian tropical rain forest evapotranspiration: Are the wet and seasonally dry rain forests any different?

This study analyzes evapotranspiration data for three wet and two seasonally dry rain forest sites in Amazonia. The main environmental (net radiation, vapor pressure deficit, and aerodynamic conductance) and vegetation (surface conductance) controls of evapotranspiration are also assessed. Our research supports earlier studies that demonstrate that evapotranspiration in the dry season is higher than that in the wet season and that surface net radiation is the main controller of evapotranspiration in wet equatorial sites. However, our analyses also indicate that there are different factors controlling the seasonality of evapotranspiration in wet equatorial rain forest sites and southern seasonally dry rain forests. While the seasonality of evapotranspiration in wet equatorial forests is driven solely by environmental factors, in seasonally dry forests, it is also biotically controlled with the surface conductance varying between seasons by a factor of approximately 2. The identification of these different drivers of evapotranspiration is a major step forward in our understanding of the water dynamics of tropical forests and has significant implications for the future development of vegetation-atmosphere models and land use and conservation planning in the region.