Method for marginal measurements of restorations: accessory device for toolmakers microscope.

Standardization of measurements for marginal fit of castings is critical. This study describes the fabrication of a device that allowed fixation of specimens on a Toolmakers microscope with identical conditions according to tri-dimensional positioning of specimens, measuring location, and seating force. The device also allows mapping of the marginal discrepancies on the entire marginal perimeter of the tooth preparation.

Restriction endonuclease banding and digestion resistant heterochromatin in triatomines, genus Panstrongylus

The present work realized a comparative study in meiosis of two triatomines, Panstrongylus herreri and P. megistus, by cytogenetic techniques involving the restriction endonucleases Hae III and Alu I and C-banding. The system of sex chromosomes in Panstrongylus is of the X1X2Y type, and experiments corroborated the common origin hypothesis of the X chromosomes by fragmentation of single X. In both species the restriction endonucleases (RE) presented banding patterns in part similar to C-banding. However, in some early meiotic phases it was possible to verify differentiation of the heterochromatic pattern. This work suggests that other elements besides presence of recognition sites, such as chromatin packing degree and DNA-protein interaction, act in RE results, since digestion patterns occur in early spermatogenesis. However, metaphase chromosomes were practically inaccessible to the endonucleases.

Skin test and tick immune status in susceptible and resistant cattle in Brazil

A cutaneous hypersensitivity test (CHT) was used to correlate host resistance to ticks and type of reaction elicited to unfed larval extract-ULE of the cattle tick Boophilus microplus in European and Indian cattle. Twenty calves were separated into four groups of five animals each: naïve or preinfested Indian or European cattle. CHT was induced by intradermal inoculation of 0.1 ml of ULE cattle tick B. microplus (50 μg protein) in the calf ear. Ear thickness was measured using calipers before and 10 min, 1, 2, 6, 18, 24, 48, 72, 96, and 144 h postinoculation (PI). Preinfested European calves showed only an immediate type reaction with maximum response (75% increase in ear thickness) at 10 min PI. On the other hand, preinfested Indian calves presented an immediate response with maximum reaction (70% increase in ear thickness) between 10 min and one hour PI, and a delayed type reaction at 72 h PI (60% increase in ear thickness). These results point out the crucial role of the cellular immune response of cattle in the expression of resistance to cattle tick B. microplus. Skin test might be useful in the ranking of cattle according to the susceptibility/resistance to ticks.

Antigens from Rhipicephalus sanguineus ticks elicit potent cell-mediated immune responses in resistant but not in susceptible animals

In the present study we compared the immunological reactions between Rhipicephalus sanguineus tick-infested susceptible (dogs and mice) and tick-resistant hosts (guinea pigs), elucidating some of the components of efficient protective responses against ticks. We found that T-cells from guinea pigs infested with adult ticks proliferate vigorously in the presence of concanavalin A (ConA), whereas ConA-induced cell proliferation of tick-infested mice and dogs was significantly decreased at 43.1 and 94.0%, respectively, compared to non-infested controls. Moreover, cells from mice and dogs submitted to one or three successive infestations did not exhibit a T-cell proliferative response to tick antigens, whilst cells from thrice tick-infested guinea pigs, when cultured with either a tick extract or tick saliva, displayed a significant increase in cell proliferation. Also, we evaluated the response of tick-infested mice to a cutaneous hypersensitivity test induced by a tick extract. Tick-infested mice developed a significant immediate reaction, whereby a 29.9% increase in the footpad thickness was observed. No delayed-type hypersensitivity (DTH) reaction was detected. Finally, the differential cell count at the tick attachment site in repeatedly infested mice exhibited a 6.6- and 4.1-fold increase in the percentage of eosinophils and neutrophils, respectively, compared to non-infested animals, while a decrease of 77.0-40.9 in the percentage of mononuclear cells was observed. The results of the cutaneous hypersensitivity test and the cellular counts at the tick feeding site for mice support the view that tick-infested mice develop an immune response to R. sanguineus ticks very similar to dogs, the natural host of this species of tick, but very different from guinea pigs (resistant host), which develop a DTH reaction in addition to a basophil and mononuclear cell infiltration at the tick-attachment site. In conclusion, saliva introduced during tick infestations reduces the ability of a susceptible animal host to respond to tick antigens that could stimulate a protective immune response. As a consequence, the animals present a lack of DTH response and disturbed cellular migration to tick feeding site, which can represent a deficient response against ticks. © 2003 Elsevier B.V. All rights reserved.

Effects of dentin collagen removal on microleakage of bonded restorations

Purpose: To evaluate the effects of removing dentin collagen exposed by acid etching on the microleakage of bonded restorations with and without flowable composite application and submitted to thermocycling and long-term water storage. Materials and Methods: Standardized Class V cavities were prepared in 180 bovine incisors. They were randomly assigned to three groups according to the adhesive technique used. Conventional group (C): Single Bond was applied according to the manufacturer's instructions and Z250 composite was placed. Hypochlorite group (H): After acid etching a 10% NaOCl aqueous solution was applied for 1 min, then Single Bond and Z250 were applied. Hypochlorite and Flowable group (HF): Similar to group H, but following adhesive application, a thin layer of Natural Flow flowable composite was applied before the Z250. Each group was divided into three subgroups (0, 6, 12), which remained immersed in distilled water for 24 h or 6 or 12 months and underwent 500, 1500 or 2500 thermal cycles, respectively. At the end of each storage time, the specimes were stained with silver nitrate, decalcified, immersed in methyl salicylate for clearing and observed under a stereomicroscope to determine microleakage (scores 0 to 4). The data were analyzed using the Kruskal-Wallis and the Multiple Comparison Tests (α = 0.05). Results: After 12 months, every group showed significant increases in microleakage. There was no significant difference between Groups H and HF for the three different periods of time, but they showed statistically less microleakage than Group C. Conclusion: The removal of dentinal collagen reduced the marginal microleakage when compared to the conventional technique. The use of the flowable composite did not produce significant effects. No technique was completely effective in preventing microleakage.

Clinical evaluation of proximal contacts of Class II esthetic direct restorations

Objective: This study evaluated the effectiveness of proximal contacts in Class II restorations using two types of matrix bands (steel and polyester) with two different restoration techniques (incremental and with prepolymerized particles). Method and materials: Eighty-eight Class II adjacent restorations using Prodigy resin composite were performed: 44 with the incremental technique (22 with steel matrix bands, 22 with polyester matrix bands) and 44 utilizing prepolymerized resin particles (22 steel matrix, 22 polyester matrix). The restorations were clinically evaluated at baseline and at 6, 12, and 18 months. Proximal contacts obtained immediately after restoration procedure in all restorations were satisfactory. Results: No statistically significant alterations were found in 18 months of evaluation. Conclusion: Regardless of the utilized resin composite, there were no differences in the amount of proximal contact variations with respect to tested techniques and matrices.

SEM analysis of internal adaptation of adhesive restorations after contamination with saliva

Purpose: This study tested the null hypothesis that different treatments of saliva-contaminated substrate would not affect microgap formation at the dentin walls of bonded restorations. Materials and Methods: Forty freshly extracted human molars received standardized Class V preparations on buccal and lingual surfaces. The specimens were assigned to four experimental groups (n = 20): [G1] no contamination (control group), [G2] saliva contamination (10 s) after etching followed by 5 s air stream; [G3] saliva contamination after etching and rinsed for 10 s; and [G4] re-etching for 10 s after saliva contamination. All specimens were restored with a one-bottle adhesive (Single Bond, 3M ESPE) and microhybrid composite resin (Filtek Z250, 3M ESPE) according to the manufacturer's instructions. The specimens were thermocycled, sectioned through the center of the restoration, and then processed for SEM. Microgaps were measured at the axial wall at 1500X magnification. The data were submitted to Kruskal-Wallis nonparametric statistical analysis at p < 0.05. Results: The data revealed that different groups resulted in a statistically significant difference (p < 0.01) in gap formation. Air drying [G2] and rinsing [G3] the saliva-contaminated dentin resulted in similar microgap values (p > 0.05). However, re-etching the dentin after saliva contamination [G4] increased microgap formation (p < 0.05) when compared with the groups G1 and G2. Although air drying and rinsing produced results comparable to noncontaminated dentin, the presence of microgaps was not completely eliminated. Conclusion: Contaminated saliva did not prevent hybrid layer formation; however, it did reduce the adaptation of the restorative material to bonded surfaces.

Scanning electron microscope analysis of internal adaptation of materials used for pulp protection under composite resin restorations

Purpose: The aim of this study was to evaluate the interfacial microgap with different materials used for pulp protection. The null hypothesis tested was that the combination of calcium hydroxide, resin-modified glass ionomer, and dentin adhesive used as pulp protection in composite restorations would not result in a greater axial gap than that obtained with hybridization only. Materials and Methods: Standardized Class V preparations were performed in buccal and lingual surfaces of 60 caries-free, extracted human third molars. The prepared teeth were randomly assessed in six groups: (1) Single Bond (SB) (3M ESPE, St. Paul, MN, USA); (2) Life (LF) (Kerr Co., Romulus, MI, USA) + SB; (3) LF + Vitrebond (VT) (3M ESPE) + SB; (4) VT + SB; (5) SB + VT; (6) SB + VT + SB. They were restored with microhybrid composite resin Filtek Z250 (3M ESPE), according to the manufacturer's instructions. However, to groups 5 and 6, the dentin bonding adhesive was applied prior to the resin-modified glass ionomer. The specimens were then thermocycled, cross-sectioned through the center of the restoration, fixed, and processed for scanning electron microscopy. The specimens were mounted on stubs and sputter coated. The internal adaptation of the materials to the axial wall was analyzed under SEM with × 1,000 magnification. Results: The data obtained were analyzed with nonparametric tests (Kruskal-Wallis, p ≤ .05). The null hypothesis was rejected. Calcium hydroxide and resin-modified glass ionomer applied alone or in conjunction with each other (p < .001) resulted in statistically wider microgaps than occurred when the dentin was only hybridized prior to the restoration. ©2005 BC Decker Inc.

Restorative treatment on class I and II restorations in primary molars: A survey of Brazilian dental schools

A survey was sent to 70 Brazilian dental schools evaluating techniques and restorative materials being taught for Class I and II preparation in posterior primary teeth by Pediatric Dentistry courses. After a 54% response rate, marked teaching diversity was found among Brazilian dental schools. Amalgam continues to be taught, but a tendency of preference towards more esthetic-like materials was observed.

Evaluation of the antimicrobial susceptibility of methicillin-resistant Staphylococcus aureus isolated from human infections

Multiresistant Staphylococcus aureus constitutes an important public health problem, especially in view of its possible spread in nosocomial environments. In the present work, we analyzed the susceptibility profile of 80 S. aureus stains from human infections resistant to at least 10 drugs. For this study, the techniques used were the disk method and minimum inhibitory concentration (MIC) of the following drugs: cefuroxime, ciprofloxacin, clindamycin, erythromycin, gentamycin, imipenem, oxacillin, rifampicin, tetracycline and vancomycin, according the criteria of the National Committee for Clinical Laboratory Standards (NCCLS). Methicillin was included in the antibiogram as a marker, which is usually used in drugs selection for the treatment of staphylococcal infections. Results indicated that the most effective drug was vancomycin. For the other 10 drugs, the percentage of resistant strains ranged from 85% to 93.75%. In relation to the MICs, it was observed that vancomycin (MIC 90% = 0.615ug/ml) was the most effective drug; followed by rifampicin (MIC 90% = 2.6ug/ml) and ciprofloxacin (MIC 90% = 26.6ug/ml). The drugs that showed the least effective activity were cefuroxime, clindamycin, erythromycin, gentamycin, and oxacillin. On the other hand, observation of β-lactamase production revealed that most of the methicillin-resistant strains produced β-lactamase (83.7%), potentiating the risks of nosocomial infections. In general, vancomycin still continues to be one of the most effective drugs for staphylococcal infections therapy.

Influence of cavity preparation and curing method on the marginal seal of resin composite restorations: an in vitro evaluation.

OBJECTIVE: To evaluate the influence of cavity design and photocuring method on the marginal seal of resin composite restorations. METHOD AND MATERIALS: Seventy-two bovine teeth were divided into 2 groups: group 1 received box-type cavity preparations, and group 2 received plate-type preparations. Each group was divided into 3 subgroups. After etching and bonding, Z250 resin composite (3M Espe) was applied in 2 equal increments and cured with 1 of 3 techniques: (1) conventional curing for 30 seconds at 650 mW/cm2; (2) 2-step photocuring, in which the first step was performed 14 mm from the restoration for 10 seconds at 180 mW/cm2 and the second step was performed in direct contact for 20 seconds at 650 mW/cm2; or (3) progressive curing using Jetlite 4000 (J. Morita) for 8 seconds at 125 mW/cm2 and then 22 seconds at 125 mW/cm2 up to 500 mW/cm2. The specimens were thermocycled for 500 cycles and then submitted to dye penetration with a 50% silver nitrate solution. Microleakage was assessed using a stereomicroscope. Data were analyzed using analysis of variance and Tukey test (5% level of significance). RESULTS: A statistically significant difference was found between groups when a double interaction between photocuring and cavity preparation was considered (P = .029). CONCLUSIONS: No one type of cavity preparation or photocuring method prevented micro-leakage. The plate-type preparation showed the worst dye penetration when conventional and progressive photocuring methods were used. The best results were found using the 2-step photocuring with the plate-type preparation.

In vitro evaluation of marginal leakage in bonded restorations, with mechanical or chemical-mechanical (Carisolv) removal of carious tissue

This study carried out an in vitro evaluation and comparison of the occurrence of marginal leakage in bonded restorations using mechanical or chemical-mechanical (Carisolv) removal of carious tissue. For that purpose, 40 extracted decayed human molars were divided into 4 groups: GI (burs + Prime & Bond NT + TPH), GII (Carisolv + Prime & Bond NT + TPH), GIII (burs + SBMP + Z100) and GIV (Carisolv + SBMP + Z100). After accomplishment of the restorations and thermal cycling, the teeth were exposed to dye, sectioned and qualitatively evaluated. The results demonstrated that the system of removal of carious tissue did not influence the results of microleakage at any of the cavity margins. At dentinal margins, use of the Prime & Bond NT + TPH restorative system allowed the occurrence of less microleakage than the SBMP + Z100 system.

Pattern of macrophage activation in yersinia-resistant and yersinia-susceptible strains of mice

Th1 cells, in cooperation with activated macrophages, are required to overcome Yersinia enterocolitica infection in mice. The pathway macrophages utilize to metabolize arginine can alter the outcome of inflammation in different ways. The objective of this study was to verify the pattern of macrophages activation in Y. enterocolitica infection of BALB/c (Yersinia-susceptible) and C57BL/6 (Yersinia-resistant) mice. Both strains of mice were infected with Y. enterocolitica O:8 WA 2707. Peritoneal macrophages and spleen cells were obtained on the 1st, 3rd and 5th day post-infection. The iNOS and the arginase activities were assayed in supernatants of macrophage cultures, by measuring their NO/citrulline and ornithine products, respectively. TGFβ-1 production was also assayed. The Th1 and Th2 responses were evaluated in supernatants of lymphocyte cultures, by IFN-γ and IL-4 production. Our results showed that in the early phase of Y. enterocolitica infection (1st and 3rd day), the macrophages from C57BL/6 mice produced higher levels of NO/citrulline and lower levels of ornithine than macrophages from BALB/c mice. The infection with Y. enterocolitica leads to an increase in the TGF-β1 and IL-4 production by BALB/c mice and to an increase in the IFN-γ levels produced by C57BL/6 mice. These results suggest that Y. enterocolitica infection leads to the modulation of M1 macrophages in C57Bl/6 mice, and M2 macrophages in BALB/c mice. The predominant macrophage population (M1 or M2) at the 1st and 3rd day of infection thus seems to be important in determining Y. enterocolitica susceptibility or resistance.

Multidrug-resistant urinary tract isolates of Escherichia coli from Ribeirão Preto, São Paulo, Brazil

Multiple resistances to antimicrobial drugs arising in Escherichia coli isolates may complicate therapeutic management of urinary tract infection (UTI) by this organism. In order to assess the multidrug resistance (MDR) among urinary E. coli isolates, we have tested 11 antimicrobial drugs against 67 isolates from outpatients attended in a tertiary-care teaching hospital and of 78 isolates from a municipal health unit, respectively in Ribeirão Preto, State of São Paulo, Brazil. Seventy-six percent and 22% of the isolates from the tertiary-care hospital and the municipal unit, respectively, were resistant to three or more different classes of agents, and were considered to present MDR. Among the isolates from the hospital patients, 73.0%, 65.0%, 58.0%, 58.0% and 31.0% were resistant to tetracycline, ampicillin, cephalothin, trimethoprim-sulfamethoxazole (TMP/SMX) and norfloxacin, respectively; resistance from the municipal unit patients were 31.0%, 37.0%, 8.0%, 29.0% and 12.0% respectively, to the same drugs. The predominant phenotype among the MDR isolates presented is ampicillin, TMP/SMX and tetracycline resistance. The high prevalence of drug resistance among UTI patients calls for continuous surveillance to assure effective control of this infection. © 2007 by The Brazilian Journal of Infectious Diseases and Contexto Publishing. All rights reserved.

Surface conditioning of a composite used for inlay/onlay restorations: Effect on μTBS to resin cement

Purpose: To assess the effect of the composite surface conditioning on the microtensile bond strength of a resin cement to a composite used for inlay/onlay restorations. Materials and Methods: Forty-two blocks (6 × 6 × 4 mm) of a microfilled composite (Vita VMLC) were produced and divided into 3 groups (N = 14) by composite surface conditioning methods: Gr1 - etching with 37% phosphoric acid, washing, drying, silanization; Gr2 - air abrasion with 50-l̀m Al2O3 particles, silanization; Gr3 - chairside tribochemical silica coating (CoJet System), silanization. Single-Bond (one-step adhesive) was applied on the conditioned surfaces and the two resin blocks treated with the same method were cemented using RelyX ARC (dual-curing resin cement). The specimens were stored for 7 days in water at 37°C and then sectioned to produce nontrimmed beam samples, which were submitted to microtensile bond strength testing (μTBS). For statistical analysis (one-way ANOVA and Tukey's test, · = 0.05), the means of the beam samples from each luted specimen were calculated (n = 7). Results: μTBS values (MPa) of Gr2 (62.0 ± 3.9a) and Gr3 (60.5 ± 7.9a) were statistically similar to each other and higher than Gr1 (38.2 ± 8.9b). The analysis of the fractured surfaces revealed that all failures occurred at the adhesive zone. Conclusion: Conditioning methods with 50-l̀m Al2O3 or tribochemical silica coating allowed bonding between resin and composite that was statistically similar and stronger than conditioning with acid etching.