Physicochemical and microbiological assessment of a dental adhesive doped with cashew nut shell liquid.

To evaluate i) the inhibitory and bactericidal activity of cashew nut shell liquid (CNSL) and its isolated compounds (anacardic acid and cardol) against oral bacteria; ii) the biofilm formation inhibition, resin-dentin bond strength and physicochemical properties of a dental adhesive incorporated with these substances. The antibacterial effect of CNSL, anacardic acid, and cardol were assessed by determining the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations. Effect in inhibiting biofilm formation of the adhesive incorporated with the substances (15 µg/ml) against a mixed-species biofilm of Streptococcus mutans and Candida Albicans and was determined by direct contact test. Additional Analysis included microtensile bond strength (µTBS) test, elastic modulus (EM), flexural strength (FS), degree of conversion (DC), water sorption (WS) and solubility (SL). The data were submitted to statistical analysis by one-way ANOVA and Tukey's test (p < 0.05). CNSL, anacardic acid and cardol showed antibacterial activity for all strains tested, with MIC and MBC values ranging from 3.12 to 25 µg/ml. There was no growth of colonies forming units in the adhesives incorporated with the substances. EM increased in the adhesive incorporated with anacardic acid, decreased after incorporation of cardol and it was not affected by incorporation of CNSL. The substances tested showed no effect in FS, DC, WS, SL and µTBS. In conclusion, the CNSL, anacardic acid and cardol showed antibacterial effects against oral bacteria and, the incorporation of substances did not reduce the performance of the adhesive.

Antibacterial activity of salvia officinalis L. against periodontopathogens: An in vitro study.

Being aware of the remarkable antimicrobial potential of S. officinalis L., we aimed to evaluate the antimicrobial activity of the S. officinalis dichloromethane crude extract (SOD), dichloromethane-soluble fractions (SODH and SODD), SODD subfractions (SODD1 and SODD2), and pure substances (manool, salvigenin, and viridiflorol) against periodontopathogens. This bioassay-guided study comprises five antimicrobial tests-determination of the Minimum Inhibitory Concentration (MIC), determination of the Minimum Bactericidal Concentration (MBC), determination of the antibiofilm activity, construction of the Time-kill curve (determination of Bactericidal Kinetics), and determination of the Fractional Inhibitory Concentration Index-on six clinical bacterial isolates and three standard bacterial strains involved in periodontal disease. SOD has moderate activity against most of the tested bacteria, whereas SODD1, SODH1, SODH3, and manool afford the lowest results. The Porphyromonas gingivalis (ATTC and clinical isolate) biofilm is considerably resistant to all the samples. In association with chlorhexidine gluconate, only SODH1 exerts additive action against P. gingivalis (clinical isolate). Therefore, SODH1 and manool are promising antibacterial agents and may provide therapeutic solutions for periodontal infections.

Effect of the aging of titanium and zirconia abutment surfaces on the viability, adhesion, and proliferation of cells and the adhesion of microorganisms.

STATEMENT OF PROBLEM: The longevity of dental implants depends on the maintenance of peri-implant tissue and absence of inflammation. How the physical-chemical properties intrinsic to each material over time can affect adhesion, given constant cell turnover and biofilm development, remains unclear. PURPOSE: The purpose of this in vitro study was to evaluate the influence of aging on the viability, adhesion, and proliferation of normal oral keratinocytes (Nok-si) and on the multispecies biofilm formation of Fusobacterium nucleatum (F. nucleatum), Porphyromonas gingivalis (P. gingivalis), and Streptococcus sanguinis (S. sanguinis). MATERIAL AND METHODS: Zirconia (ZrO2) and titanium (Ti) disks were analyzed by surface roughness, water contact angle, and X-ray diffraction before and after aging in an autoclave. The Nok-si cell viability was evaluated by using a 3-(4.5-dimethylthiazole-2-yl)2.5-diphenyl tetrazolium bromide assay (MTT), morphology by scanning electron microscopy (SEM), and proliferation and adhesion by using a confocal microscope. Multispecies biofilms were analyzed quantitatively by colony-forming units per milliliter (CFU/mL) and qualitatively by SEM. RESULTS: For Ti, the aging process affected the roughness and wettability. However, for ZrO2, the aging did not affect roughness but did affect wettability and the ratio of the tetragonal to monoclinic phase (P<.05). A significant difference was found in the bacterial growth for Ti (nonaged and aged) in relation to the control, and no differences were found in Ti before and after aging; however, ZrO2 had increased growth of microorganisms after aging. For ZrO2, a statistically significant difference was found between aged ZrO2 and the control (P<.001). CONCLUSIONS: The results indicate that, after the aging, Ti showed better cell adhesion and proliferation and lower biofilm adhesion than zirconia.

Susceptibility to Oral Antiseptics and Virulence Factors Ex Vivo Associated with Candida spp. Isolated from Dental Prostheses.

PURPOSE: To isolate Candida spp. from dental prosthesis users' saliva and to evaluate the isolates for the presence of several virulence factors. This research also aimed to investigate the antifungal activity of 3 commercial mouthwashes/oral antiseptic formulations containing 0.12% chlorhexidine, 0.07% cetylpyridinium, or 0.075% cetylpyridinium against planktonic and sessile (biofilm mode) yeast cells. MATERIALS AND METHODS: Forty-three Candida yeasts were isolated from 32 of 70 selected patients, and the virulence factors of C. albicans, C. krusei, C. glabrata, C. tropicalis, and C. parapsilosis species were investigated by polymerase chain reaction (PCR) and proteinase in plates. Minimum inhibitory concentration (MIC), and in vitro biofilm assay evaluated the antifungal activity of antiseptics. RESULTS: C. albicans, C. krusei, C. glabrata, C. tropicalis, and C. parapsilosis were detected in mono and mixed cultures. Only C. albicans displayed genes related to adhesion and proteinases (ALS2, ALS3, SAP1, and SAP3). The aspartate proteinase activity was found in 60.46% of isolates. The tested antiseptic formulations exhibited a MIC less than 1.25% toward yeasts in the planktonic mode. According to XTT ((2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay results, most Candida isolates and all mixed cultures formed biofilms within 24 hours. The evaluated antiseptic formulations were also active against biofilms. CONCLUSION: Most virulence factors investigated here (ALS2, ALS3, SAP1, and SAP3) occurred in the majority of the Candida spp. isolates, especially in C. albicans. The tested mouthwash formulations were effective against all the yeast isolates in both the planktonic and sessile growth modes. Developing alternative therapies that can avoid or control biofilm formation is necessary to prevent oral candidiasis and other Candida spp. infections.

Risk of Fungal Infection to Dental Patients.

Fungi can cause various diseases, and some pathogenic fungi have been detected in the water of dental equipment. This environment offers suitable conditions for fungal biofilms to emerge, which can facilitate mycological contamination. This study verified whether the water employed in the dental units of two dental clinics at the University of Franca was contaminated with fungi. This study also evaluated the ability of the detected fungi to form biofilms. The high-revving engine contained the largest average amount of fungi, 14.93 ± 18.18 CFU/mL. The main fungal species verified in this equipment belonged to the genera Aspergillus spp., Fusarium spp., Candida spp., and Rhodotorula spp. Among the isolated filamentous fungi, only one fungus of the genus Fusarium spp. did not form biofilms. As for yeasts, all the Candida spp. isolates grew as biofilm, but none of the Rhodotorula spp. isolates demonstrated this ability. Given that professionals and patients are often exposed to water and aerosols generated by the dental procedure, the several fungal species detected herein represent a potential risk especially to immunocompromised patients undergoing dental treatment. Therefore, frequent microbiological monitoring of the water employed in dental equipment is crucial to reduce the presence of contaminants.

Color stability of dental ceramics submitted to artificial accelerated aging after repeated firings.

STATEMENT OF PROBLEM: Color stability is an important factor to ensure the long-term clinical success of ceramic restorations. There is a lack of information on how color is affected by fabrication procedures, such as the number of firings. PURPOSE: The purpose of this study was to evaluate the effects that the number of firings and type of substrate have on the color stability of dental ceramic submitted to artificial accelerated aging. MATERIAL AND METHODS: Sixty specimens were fabricated: 30 metal ceramic (Verabond II + IPS d.SIGN) and 30 all-ceramic (IPS d.SIGN). Specimens were divided into 3 groups (n=10), and submitted to 2, 3, or 4 firings (+/-900 degrees C), respectively, according to the manufacturer's instructions. Color readings were obtained with a spectrophotometer before and after artificial accelerated aging, and L*, a*, and b* coordinates and total color variation (Delta E) were analyzed (2-way ANOVA, Bonferroni, alpha=05). RESULTS: For metal ceramic specimens, differences for the L* coordinates were significant (P<.05) only for the group submitted to 3 firings. With respect to the all-ceramic specimens, smaller L* coordinates were obtained for greater a* and b* coordinates, indicating that the greater the number of firings, the darker and more reddish/yellowish the specimen. All Delta E values, for all groups, were below 1.0. All-ceramic specimens submitted to 3 and 4 firings presented Delta E means differing statistically (P<.05) from those of the metal ceramic group. CONCLUSIONS: The type of substrate and number of firings affected the color stability of the ceramic material tested. Artificial accelerated aging did not produce perceptible color stability changes (Delta E<1.0).

Effect ofartificial accelerated aging on color stability and surface roughness of indirect composites.

Direct and indirect composite resins have different forms of polymerization. Some materials require a post-cure system associating light and heat enhancing clinical properties. This study assessed the changes in color and surface roughness of three indirect composite resins after accelerated aging. Twelve specimens (15 x 2 mm) were obtained for each tested material. Subsequently, the first measurements for roughness tests and colorimetric spectrophotometry (CIE L*a*b* scale) were performed. Specimens were subject to accelerated aging for 384 hours. New measurements were then performed to evaluate the resulting change. Accelerated aging produced color change and increased surface roughness in all composite resins. Solidex resin showed color changes above the clinically accepted value (DeltaE = 4.31 +/- 0.22), and roughness values (Ra = 0.088 +/- 0.008 microm) statistically lower than that of Artglass (Ra = 0.141 +/- 0.026 microm) and Targis (Ra = 0.124 +/- 0.02 microm) (p<0.001). All the indirect resins tested showed color change and increased roughness after accelerated aging. Solidex showed color stability above a quantitative level considered clinically acceptable and lower roughness values compared to the other resins.

Abrasion resistance of composites polymerized by light-emitting diodes (LED) and halogen light-curing units.

This study compared the abrasion resistance of direct composite resins cured by light-emitting diodes (LED) and halogen light-curing units. Twenty specimens (12 mm in diameter; 1.0 mm thick) of each composite resin [TPH (Dentsply); Definite (Degussa); Charisma (Heraus Kulzer)] were prepared using a polytetrafluoroethylene matrix. Ten specimens per material were cured with the LED source and 10 with the halogen lamp for 40 s. The resin discs were polished, submitted to initial surface roughness reading (Ra initial - microm) in a roughness tester and stored in water at 37 degrees C for 15 days. The specimens were weighed (M1) and submitted to simulated toothbrushing using slurry of water and dentifrice with high abrasiveness. After 100 minutes in the toothbrushing simulator, the specimens were cleaned, submitted to a new surface roughness reading (Ra final - microm) and reweighed (M2). Mass loss was determined as the difference between M1 and M2. Data were recorded and analyzed statistically by one-way ANOVA and Tukey Test at 5% significance level. The composite resin with greater size of inorganic fillers (TPH) showed the lowest mass loss and surface roughness means, indicating a higher resistance to toothbrush abrasion (p<0.05). Definite cured with LED presented the least resistance to toothbrush abrasion, showing the highest means of surface roughness and mass loss (p<0.05). The LED source did not show the same effectiveness as the halogen lamp for polymerizing this specific composite resin. When the composite resins were cured a halogen LCU, no statistically significant difference was observed among the materials (p>0.05). It may be concluded that the type of light-curing unit and the resin composition seemed to interfere with the materials' resistance to abrasion.

Endodontics pastes formulated with copaiba oil: action on oral microbiota and dentin bridge formation in dogs / Pastas endodônticas formuladas com óleo de copaíba: ação na microbiota bucal e formação de ponte dentinária em cães

This study analysed the effect of pastes formulated with calcium hydroxide P.A. and different vehicles (saline solution - paste A and Copaifera langsdorffii Desfon oil - paste B) on oral microorganisms and dentin bridge formation in dogs. The antimicrobial action of the pastes and their components was analysed by the minimum inhibitory concentration in agar gel technique. The components were diluted and tested on fifteen standard strains of microorganisms associated with endodontic diseases. The microorganisms were cultivated and after incubation data was analysed using One-Way ANOVA and Turkey's test (P≤0.05). Four superior incisors of ten animals were used to evaluate dentin bridge formation. Two incisors were capped with paste A (GA) and two with paste B (GB). After 90 days, the teeth were extracted for histological analysis and the degree of dentin bridge formation evaluated. Data was analysed by the Kruskal-Wallis test (P<0.05). The pastes and their components were classified in the following decreasing order of antimicrobial action: calcium hydroxide P.A., paste A, paste B and Copaifera langsdorffii Desfon oil. Calcium hydroxide P.A. showed significantly higher antimicrobial action than the pastes or their vehicles. No significant difference was observed between the two pastes in dentin bridge formation. Based on the microorganisms studied, it can be concluded that the pastes analysed showed similar antimicrobial potential but differed significantly from their individual components. No significant difference was observed in dentin bridge formation between the different pastes tested.

Foi avaliada a ação de pastas formuladas com hidróxido de cálcio P.A. e diferentes veículos (solução fisiológica - pasta A e óleo de Copaifera langsdorffii Desfon - pasta B) sobre microrganismos bucais e formação de ponte dentinária em cães. A ação antimicrobiana das pastas e de seus componentes individuais foi avaliada pela técnica da concentração inibitória mínima pela diluição em ágar. Os materiais foram diluídos e avaliados contra quinze cepas padrão de microrganismos relacionados a doenças endodônticas. Os microrganismos foram cultivados e, após a incubação, os dados foram analisados (Anova One-Way, Tukey, P≤0,05). Para a avaliação da formação de ponte dentinária, quatro incisivos superiores de dez animais foram tratados, sendo dois capeados com pasta A (GA) e dois com a pasta B (GB). Após 90 dias, os dentes foram extraídos para obtenção de cortes histológicos, com o objetivo de se avaliar o grau de formação de ponte dentinária. Os dados obtidos foram submetidos à análise estatística (Kruskal-Wallis, P<0,05). Segundo a ação antimicrobiana, os materiais foram classificados em ordem decrescente: hidróxido de cálcio P.A., pasta A, pasta B e óleo de Copaifera langsdorffii Desfon, com diferenças estatisticamente significantes entre o hidróxido de cálcio P.A., as pastas e os veículos. Ao final do estudo, observou-se que as duas pastas avaliadas foram semelhantes quanto à formação de ponte dentinária. Considerando-se os microrganismos selecionados, conclui-se que as pastas avaliadas foram semelhantes entre si em termos de potencial antimicrobiano, diferindo dos componentes individuais. Em relação à formação de ponte dentinária, não foram observadas diferenças significantes entre os dentes tratados com as diferentes pastas.

Polymerization shrinkage stress of composites photoactivated by different light sources.

The purpose of this study was to compare the polymerization shrinkage stress of composite resins (microfilled, microhybrid and hybrid) photoactivated by quartz-tungsten halogen light (QTH) and light-emitting diode (LED). Glass rods (5.0 mm x 5.0 cm) were fabricated and had one of the surfaces air-abraded with aluminum oxide and coated with a layer of an adhesive system, which was photoactivated with the QTH unit. The glass rods were vertically assembled, in pairs, to a universal testing machine and the composites were applied to the lower rod. The upper rod was placed closer, at 2 mm, and an extensometer was attached to the rods. The 20 composites were polymerized by either QTH (n=10) or LED (n=10) curing units. Polymerization was carried out using 2 devices positioned in opposite sides, which were simultaneously activated for 40 s. Shrinkage stress was analyzed twice: shortly after polymerization (t40s) and 10 min later (t10min). Data were analyzed statistically by 2-way ANOVA and Tukey's test (alpha=5%). The shrinkage stress for all composites was higher at t10min than at t40s, regardless of the activation source. Microfilled composite resins showed lower shrinkage stress values compared to the other composite resins. For the hybrid and microhybrid composite resins, the light source had no influence on the shrinkage stress, except for microfilled composite at t10min. It may be concluded that the composition of composite resins is the factor with the strongest influence on shrinkage stress.

Influencia de los tipos de anclaje de los filamentos en la retención de streptococcus mutans en cepillos dentales: estudio preliminar / Influence of the types of filaments anchoring in the retention of streptococcus mutans on toothbrushes: preliminary study

Este estudio evaluó la retención del S. mutans (ATCC 25175) en los cepillos dentales Oral B Complete® y Sensodyne Esmalte Care®, que poseen distintas características de fijación y anclaje de los filamentos en sus partes activas. Nueve cepillos dentales de cada marca comercial fueron esterilizados en autoclave y, a continuación, inoculados con S. mutans (ATCC 25175), previamente desarrollado en caldo Brain Heart Infusion (BHI). Los análisis de retención bacteriana se realizaron en los tempos de 04, 12 y 24 horas de incubación, a 37ºC y en microaerofilia, en triplicata. En esas etapas, los cepillos fueron lavados con agua esterilizada e introducidos en tubos Falcon con caldo BHI, del cual fueron preparadas diluciones decimales hasta 10-3 para las cuatro primeras horas, hasta 10-4 para 12 horas, y hasta 10-5 para 24 horas de incubación. Alícuotas de esas diluciones fueron sembradas en la superficie del Ágar BHI, siendo las placas incubadas en microaerofilia por 24h a 37ºC. Tras la incubación, fue realizado un recuento de las unidades formadoras de colonia por mL (UFC/mL) y el análisis estadístico (Tests de Tukey pareado, p?0,05). Fueron observadas diferencias estadísticamente significantes (p?0,05) entre lo tiempos de evaluación de 12 horas. Concluyese que el cepillo dental Oral B Complete® presentó, comparativamente a Sensodyne Esmalte Care®, mayor retención del S. mutans (ATCC 25175).

This work evaluated the retention of S. mutans ATCC 25175 in the Oral B Complete and Sensodyne Esmalte Care toothbrushes that have distinct characteristics of insertion and anchorage of the filaments in its active parts. Nine toothbrushes of each trademark were sterilized in autoclave and, following this procedure, inoculated with S. mutans ATCC 25175, previously developed in Brain Heart Infusion (BHI).The analyses of bacterial retention occurred in the times of 04, 12 and 24 hours after incubation, at 37ºC and in microaerophilic, in triplicate. In these stages, the toothbrushes were washed with sterilized water and enclosed in Falcon tubes with BHI broth, of which decimal dilutions up to 10-3 were made for the four first hours, up to 10-4 for 12 hours, and up to 10-5 for 24 hours of incubation. Aliquots of these dilutions were sown in the surface of agar BHI, and the Petri dishes were incubated in microaerophilic for 24 hours, in a temperature of 37ºC. After the incubation, the counting of the colony forming units and the statistical analysis (Tukey Test paired, p?0.05) were performed. Significant statistical differences were observed (p?0.05) between the times of evaluation of 12 hours. It was concluded that the Oral B Complete toothbrush presents, compared with Sensodyne Esmalte Care, greater retention of S. mutans ATCC 25175.

Antimicrobial and mechanical properties of acrylic resins with incorporated silver-zinc zeolite - part I.

OBJECTIVE: The purpose of this in vitro study was to evaluate the antimicrobial activity of acrylic resins containing different percentages of silver and zinc zeolite, and to assess whether the addition of zeolite alters the flexural and impact strength of the resins. BACKGROUND: The characteristics of acrylic resins support microorganism development that can threaten the health of the dentures user. MATERIAL AND METHODS: A microwave-polymerised (Onda-Cryl) and two heat-polymerised (QC20 and Lucitone 550) acrylic resins were used. The materials were handled according to the manufacturers' instructions. Fifty rectangular-shaped specimens (8 x 10 x 4mm) were fabricated from each resin and assigned to 5 groups (n = 10) according to their percentage of Irgaguard B5000 silver-zinc zeolite (0%- control, 2.5%, 5.0%, 7.5% and 10%). Flexural strength and Izod impact strength were evaluated. The antimicrobial activity against two strains of Candida albicans and two strains of Streptococcus mutans was assessed by agar diffusion method. Data were analysed statistically by one-way anova and Tukey's test at 5% significance level. RESULTS: The addition of 2.5% of Irgaguard B5000 to the materials resulted in antimicrobial activity against all strains. Flexural strength decreased significantly with the addition of 2.5% (QC20 and Lucitone 550) and 5.0% (Onda-Cryl) of Irgaguard B5000. The impact strength decreased significantly with the addition of 2.5% (Lucitone 550) and 5.0% (QC20 and Onda-Cryl) of zeolite. CONCLUSION: The addition of silver-zinc zeolite to acrylic resins yields antimicrobial activity, but may affect negatively the mechanical properties, depending on the percentage of zeolite.

Effectiveness of a new toothbrush design versus a conventional tongue scraper in improving breath odor and reducing tongue microbiota.

For centuries, specific instruments or regular toothbrushes have routinely been used to remove tongue biofilm and improve breath odor. Toothbrushes with a tongue scraper on the back of their head have recently been introduced to the market. The present study compared the effectiveness of a manual toothbrush with this new design, i.e., possessing a tongue scraper, and a commercial tongue scraper in improving breath odor and reducing the aerobic and anaerobic microbiota of tongue surface. The evaluations occurred at 4 moments, when the participants (n=30) had their halitosis quantified with a halimeter and scored according to a 4-point scoring system corresponding to different levels of intensity. Saliva was collected for counts of aerobic and anaerobic microorganisms. Data were analyzed statistically by Friedman's test (p<0.05). When differences were detected, the Wilcoxon test adjusted for Bonferroni correction was used for multiple comparisons (group to group). The results confirmed the importance of mechanical cleaning of the tongue, since this procedure provided an improvement in halitosis and reduction of aerobe and anaerobe counts. Regarding the evaluated methods, the toothbrush's tongue scraper and conventional tongue scraper had a similar performance in terms of breath improvement and reduction of tongue microbiota, and may be indicated as effective methods for tongue cleaning.

Adsorção de Candida albicans em resinas utilizadas em bases de próteses removíveis / Adsorption of Candida albicans in resins used for manufacture of removable prosthesis bases

A resina acrílica termoativada tem sido o material de escolha para confecção de bases de próteses removíveis há mais de 60 anos. Mais recentemente, as resinas ativadas por micro-ondas e as semi-rígidas foram introduzidas, porém pouco ainda se sabe a respeito da capacidade de retenção de biofilme nesses materiais, especialmente do último. Esse estudo avaliou a adsorção de Candida albicans em quatro resinas utilizadas em bases de próteses removíveis. Os materiais avaliados foram: Onda-Cryl (Clássico, polimerização por microondas), QC-20 (Dentsply, polimerização térmica de ciclo curto), Lucitone (Denstply, polimerização térmica) e Odontoflex (Odontoloflex, resina de poliamida termo-injetada). Dez corpos-de-prova (10,0X5,0X2,0mm) foram preparados para cada material, de acordo com as recomendações dos fabricantes. Os corpos-de-prova foram esterilizados (121ºC, 25min, 1 atm), colocados em tubos contendo 10,0mL de caldo RPMI (Inlab) inoculados com C. albicans ATCC 28366 (106 CFU/mL) e incubados em shaker (48h/37ºC). A seguir, os corpos-de-prova foram transferidos para outros tubos de ensaio e lavados com água destilada esterilizada (10s), sendo novamente colocados em caldo RPMI sob agitação (10s). Aliquotas do caldo RPMI foram semeadas em meio de cultura sólido agar Sabouraud (Difco), que foi então incubado (48h/37ºC). As colônias formadas foram contadas e os resultados analisados (Anova One-Way, Tukey, p≤0,05). De acordo com a adsorção de C. albicans ATCC 28366, os materiais foram classificados na seguinte ordem decrescente: 1) Odontoflex (690.000UFC/mL), 2) OndaCryl (454.000UFC/mL), 3) Lucitone 550 (256.000UFC/mL) e 4) QC-20 (254.000UFC/mL). Odontoflex e Onda-Cryl diferiram significantemente (p≤0,05) entre si e dos outros materiais. Lucitone 550 e QC-20 foram similares em termos de adsorção da levedura. Conclui-se que a maior retenção de C. albicans ATCC 28366 foi observada para a resina de poliamida e menor para a resina termoativada QC 20.

Heat-activated resin has been selected as material for the preparation of removable prosthesis basis for over 60 years. Microwave-activated and semi-rigid resins have been introduced more recently; however, little is known about their ability to retain biofilms, especially in the case of semi-rigid materials. Therefore, this study evaluated C. albicans adsorption onto four resins employed in removable prosthesis basis. The materials Onda-Cryl (Classic, microwave polymerization), QC-20 (Dentsply, short-cycle heat-activated polymerization), Lucitone (Denstply, heatactivated polymerization), and Odontoflex (Odontoloflex, thermally injected polyamide resin) were investigated. Ten specimens (10.0X5.0X2.0mm) were prepared for each material, following the manufacturer's instructions. The samples were sterilized (121ºC, 25min, 1 atm), placed in tubes containing 10.0 mL of RPMI broth (Inlab) inoculated with C. albicans ATCC 28366 (106 CFU/mL), and incubated in a shaker (48h/37ºC). Next, the specimens were transferred to other test tubes and washed with sterilized distilled water (10s), and were then placed in RPMI broth, under agitation (10s). Aliquots of the RPMI broth were seeded in solid agar Sabouraud culture medium (Difco), which was then incubated (48h/37ºC). The resulting colonies were counted, and the data were analyzed (Anova One-Way, Tukey, p≤0.05). On the basis of C. albicans ATCC 28366 adsorption, the materials were classified in the following decreasing order: 1) Odontoflex (690,000CFU/mL), 2) Onda-Cryl (454,000CFU/mL), 3) Lucitone 550 (256,000CFU/mL), and 4) QC-20 (254,000CFU/mL). Odontoflex and Onda-Cryl were significantly different (p≤0.05), and they were also statistically different from the other tested materials. Lucitone 550 and QC-20 were similar in terms of yeast adsorption. In conclusion, larger and smaller C. albicans ATCC 28366 retention were verified for the polyamide resin and the heat-activated resin QC 20, respectively.

Desensitizing bioactive agents improves bond strength of indirect resin-cemented restorations: preliminary results.

OBJECTIVE: The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material. MATERIALS AND METHOD: Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5): Group I: acid etching + Prime & Bond NT (Dentsply); Group II: application of a bioactive glass (Biosilicato) + acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita); Group IV: Biosilicato + One-up Bond F. Indirect composite resin (Artglass, Kulzer) cylinders (6 x 10 mm) were fabricated and cemented to the teeth with a dual-cure resin-based cement (Enforce, Dentsply). After cementation, the specimens were stored in artificial saliva at 37 degrees C for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC) with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence). RESULTS: Groups I, II and III had statistically similar results (p>0.05). Group IV had statistically significant higher bond strength means (p<0.05) than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups. CONCLUSION: The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems.

Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials.

This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.

Color stability of composites subjected to accelerated aging after curing using either a halogen or a light emitting diode source.

The purpose of this study was to evaluate, in vitro, the color stability of three composite resins of two different shades (A3 and C3) cured with either a quartz tungsten halogen (QTH) or a light emitting diode (LED) source. Forty specimens (20 x 2 mm) were prepared for each composite (Tetric Ceram, Heliomolar and Esthet-X), being 20 for each shade. In each group, 10 specimens were light-cured using the QTH unit and 10 with the LED source. The shade of the materials was evaluated before and after submitting the specimens to artificial accelerated aging (4 h UV-B/4 h condensing vapor), using a reflection spectrophotometer. deltaE means were calculated and analyzed statistically by 2-way ANOVA and Tukey's test at 5% significance level. Both A3 and C3 shades of Esthet-X composite resin showed the lowest color change when cured with the QTH light, while Tetric C3 cured with the QTH light showed the highest color change.

In vitro antimicrobial activity of irreversible hydrocolloid impressions against 12 oral microorganisms.

This study evaluated in vitro the antimicrobial activity of irreversible hydrocolloids (one containing an antimicrobial agent) prepared with water or with a 0.2% chlorhexidine digluconate solution against 12 strains of the oral microbiota. Twenty specimens (0.5x1.0 cm) for each group (1. Jeltrate mixed with water; 2. Jeltrate mixed with 0.2% chlorhexidine digluconate solution; 3. Greengel mixed with water; 4. Greengel mixed with 0.2% chlorhexidine digluconate solution) were prepared under sterile conditions and placed in culture media inoculated with the indicator strains. After incubation in aerobiosis or microaerophilia, inhibition of the microbial growth was measured and the results were interpreted. The normal adherence curve revealed a non-normal distribution of the data, so the non-parametric Friedman Test was performed (p<0.05). The antimicrobial activity of the groups was classified in the following order: 1, 3, 4, and 2. The results suggest that the method of preparing irreversible hydrocolloids with a 0.2% digluconate chlorhexidine solution is more effective than the incorporation of an antimicrobial agent in the powder to reduce cross-contamination caused by impressions.

Evaluation of fluorescence of dental composites using contrast ratios to adjacent tooth structure: a pilot study.

STATEMENT OF THE PROBLEM: Fluorescence is an optical signal that is present in natural teeth and some dental restorative materials as a consequence of its molecules energetic decrease. Restorative materials need to match the fluorescence properties of surrounding tooth structure to achieve the best esthetics and appear undetectable. PURPOSE: The fluorescence of 10 commercial composites (shade A2 or equivalent) was tested against that of tooth structure using contrast differences. MATERIALS AND METHODS: Thirty-three standard preparations (3.0-mm wide and 2.00-mm depth) were done on mean maxillaries incisors and divided into 10 groups containing three test samples each. High-definition images of the restored areas and adjacent tooth structure were obtained both under white light of the visible spectrum (control) and ultraviolet light (UV-A=300/ 400 nm). The contrast between composites and tooth structure, expressed in absolute values, was analyzed through digital processing Matlab and Origin softwares and by one-way analysis of variance and Tukey's test (p

A influência da disposição das cerdas de escovas dentais manuais na remoção de placa dental / The influence of manual toothbrush bristle arrangement on dental plaque removal

This crossover study aimed to compare plaque removal efficiency of two manual toothbrushes with identical design, the exception being the pattern of bristle arrangement. Twenty-six subjects were selected following inclusion and exclusion criteria. Dental plaque was scored before and after seven days of use of each toothbrush (Sanifill Smooth® – T1 andSanifill Active Smooth® – T2) employing the Turesky Plaque Index. Plaque Index values were handled with parametrical statistics employing Analysis of Variance (p<0.05) and, later, the Tukey Test. At the end of the trial, each subject was asked which toothbrush they preferred. Results: plaque scores for toothbrush T1 were not statistically different from those for toothbrush T2. Subjects showed a distinct preference for toothbrush T1. Conclusion: there was no differencein terms of plaque removal when toothbrushes T1 and T2 were compared, although patients showed a higher preference for toothbrush T1. Thus the different toothbrushes bristles arrangements did not influence the dental plaque removal.

Este estudo cruzado se propôs a comparar a eficiência de remoção de placa dental de duas escovas manuais com modelos idênticos, exceto para o padrão da disposição das cerdas. Vinte e seis sujeitos foram selecionados de acordo com critérios de inclusão e exclusão. Placa dental foi mensurada antes e após sete dias de uso com cada uma das escovas (Sanifill Smooth® – T1 and Sanifill Active Smooth® – T2) utilizando-se o Índice de Placa de Turesky. No final do estudo, cada paciente foi questionado sobre qual a escova preferida. Os valores do Índice de Placa para T1 não foram estatisticamente diferentes para os da escova T2. Não houve diferença em termos de remoção de placa quando as escovas T1 e T2 foram comparadas, embora os pacientes tenham demonstrado grande preferência pela escova T1. Assim, as diferenças nas disposições das cerdas das escovas dentais manuais não influenciaram na remoção de placa dental.