Cleaning of long oval canals with WaveOne Gold system associated with different irrigant agitation protocols

Aim: The aim of the study was to evaluate the cleaning of mandibular incisors with WaveOne Gold® (WO) under different preparation techniques. Methods: A total of 210 human mandibular incisors were selected and divided into seven groups (n = 30), prepared by WO single-files (Small 20/.07 ­ WOS; Primary 25/.07 ­ WOP; Medium 35/.06 ­ WOM; or Large 45/.05 - WOL) and sequential-file techniques (WOS to WOP; WOS to WOM; and WOS to WOL). Further subdivision was made according to irrigation protocol: control group (manual irrigation - CON), E1 Irrisonic® - EIR, and EDDY® - EDD. Debris removal and the smear layer were evaluated by scanning electron microscopy. Data were analyzed by using Spearman's correlation test. The significance level was set at 5%. Results: For debris and smear layer removal, WOS and WOP, EIR differed from CON and EDD (p <0.05). Conclusion: Regardless of the instrumentation used, the agitation of the irrigant solution provided better cleanability. These findings reinforce the need for agitation techniques as adjuvants in cleaning root canal systems in mandibular incisors

Short implants to support mandibular complete dentures - photoelastic analysis

Abstract This study evaluated the stress behavior around short implants in edentulous atrophic mandibles. Six groups included implants with two diameters regular and wide (4 and 5 mm) and three lengths (5, 7 and 9 mm) as follows: Ci9 (9 x 4 mm), Ci7 (7 x 4 mm), Ci5 (5 x 4 mm), Wi9 (9 x 5 mm), Wi7 (7 x 5 mm) and Wi5 (5 x 5 mm). These groups were compared to the control group CG (11 x 4 mm). The analysis was performed with the photoelastic method (n = 6). Each model comprised 4 implants with the same length and diameter connected by a chromium-cobalt bar that simulates a fixed denture. A 0.15 kg force was applied at the end of the cantilever (15 mm), and the maximum shear stress was recorded around the distal and subsequent implants. The stress values were determined, and the quantitative data (Fringes®) were submitted to statistical analysis with one-way ANOVA and the Dunnett test (p < 0.05). It was observed that the reduction in implant length increased stress values with a significant difference (p < 0.05) between CG Ci7 and Ci5, while the increase in implant diameter reduced the stress values without any differences found between short and long implants. Implants with 5 and 7 mm with regular diameter increased stress levels while short implants with larger diameters experienced similar stress to that of longer implants.

Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants

Abstract This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical), implant connection (external hexagon, EH or internal hexagon, IH), and occlusal loading (axial or oblique), for both immediately and delayed loaded implants. Analysis of variance at 95%CI was used to evaluate the peak maximum principal stress and strain in bone after applying a 100 N occlusal load. The results showed that the type of prosthetic abutment influences bone stress/strain in only immediately loaded implants. Attachment of conical abutments to IH implants exhibited the best biomechanical behavior, with optimal distribution and dissipation of the load in peri-implant bone.

The effect of fluoride toothpaste on root dentine demineralization progression: a pilot study

The anticaries effect of fluoride (F) toothpaste containing 1100 µg F/g in reducing enamel demineralization is well established, but its effect on dentine has not been extensively studied. Furthermore, it has been shown that toothpaste containing a high F concentration is necessary to remineralize root dentine lesions, suggesting that a 1100 µg F/g concentration might not be high enough to reduce root dentine demineralization, particularly when dentine is subjected to a high cariogenic challenge. Thus, the aim of this pilot study was to evaluate in situ the effect of F toothpaste, at a concentration of 1100 µg F/g, on dentine demineralization. In a crossover and double-blind study, conducted in two phases of 14 days, six volunteers wore a palatal appliance containing four slabs of bovine root dentine whose surface hardness (SH) was previously determined and to which a 10% sucrose solution was applied extra-orally 8×/day. Volunteers used a non-F toothpaste (negative control) or F toothpaste (1100 µg F/g, NaF/SiO2) three times a day. On the 10th and 14th days of each phase, two slabs were collected and SH was determined again. Dentine demineralization was assessed as percentage of SH loss (%SHL). The effect of toothpaste was significant, showing lower %SHL for the F toothpaste group (42.0 ± 9.7) compared to the non-F group (62.0 ± 6.4; p < 0.0001), but the effect of time was not significant (p > 0.05). This pilot study suggests that F toothpaste at 1100 µg F/g is able to decrease dentine caries even under a high cariogenic challenge of biofilm accumulation and sugar exposure.

Candida albicans biofilms and MMA surface treatment influence the adhesion of soft denture liners to PMMA resin

The effect of Candida albicans biofilms and methyl methacrylate (MMA) pretreatment on the bond strength between soft denture liners and polymethyl methacrylate (PMMA) resin was analyzed. Specimens were prepared and randomly divided with respect to PMMA pretreatment, soft liner type (silicone-based or PMMA-based), and presence or absence of a C. albicans biofilm. Samples were composed of a soft denture liner bonded between two PMMA bars. Specimens (n = 10) were incubated to produce a C. albicans biofilm or stored in sterile PBS for 12 days. The tensile bond strength test was performed and failure type was determined using a stereomicroscope. Surface roughness (SR) and scanning electron microscopy (SEM) analysis were performed on denture liners (n = 8). Highest bond strength was observed in samples containing a silicone-based soft liner and stored in PBS, regardless of pretreatment (p < 0.01). Silicone-based specimens mostly underwent adhesive failures, while samples containing PMMA-based liners predominantly underwent cohesive failures. The silicone-based specimens SR decreased after 12 days of biofilm accumulation or PBS storage, while the SR of PMMA-based soft liners increased (p < 0.01). The PMMA-based soft liners surfaces presented sharp valleys and depressions, while silicone-based specimens surfaces exhibited more gentle features. In vitro exposure to C. albicans biofilms reduced the adhesion of denture liners to PMMA resin, and MMA pretreatment is recommended during relining procedures.

Anaerobic enhancement of protease secretion by periodontal Candida albicans strains / Aumento anaeróbio da secreção de protease pelas cepas de Candida albicans periodontal

Among other non-bacterial organisms, yeasts have been isolated from subgingival sites with relative frequency. Candida albicans is the species most commonly isolated although its role in periodontal disease has not been established. Objective: This study evaluated the secretion patterns of aspartyl-protease (Sap) by periodontal and nonperiodontal Candida albicans strains in normoxic and anoxic conditions. Material and methods: Periodontal strains (n=10; periodontal pockets ≥3.00 mm) and nonperiodontal Candida albicans strains (n=10) were grown under normoxic and anoxic conditions in protease-inducible broth. Sap activities were quantified in supernatants using azocasein as substrate. Whole-protein contents in supernatants were determined by Bradford’s method. Specific protease activities (Sap activity.protein-1) were assessed and compared. Results: While nonperiodontal strains secrete similar amounts of Sap under both atmospheric conditions, periodontal strains secrete reduced amounts in the presence of molecular oxygen. Conclusion: Despite the limited number of assayed isolates, the possibilities of adaptation or selection of candidal strains to periodontal microenvironment may be considered...

Entre organismos não bacterianos, as leveduras têm sido isoladas de sítios subgengivais com relativa frequência. Candida albicans é a espécie mais comumente isolada, embora seu papel na doença periodontal não esteja estabelecido. Objetivo: Este estudo avaliou os padrões de secreção de aspartil-protease (Sap) por cepas periodontais e não periodontais de Candida albicans em situações de normóxia e anóxia. Material e métodos: Cepas periodontais (n=10; bolsas periodontais ≥3,00 milímetros) e cepas de não periodontais (n=10) Candida albicans foram cultivadas sob condições normóxicas e anóxicas em caldo de protease-induzida. A atividade Sap foi quantificada em sobrenadantes utilizando azocaseína como substrato. O conteúdo de proteínas totais nos sobrenadantes foi determinado pelo método de Bradford. Atividades de protease específica (atividade de proteína Sap-1) foram avaliadas e comparadas. Resultados: Apesar das cepas não periodontais secre¬tarem quantidades semelhantes de Sap em ambas as condições atmosféricas, as cepas periodontais secretam quantidades reduzidas na presença de oxigênio molecular. Conclusão: Apesar do número limitado de amostras analisadas, as possibilidades de adaptação ou seleção de cepas de Candida no microambiente periodontal pode ser considerada...

Influence of substratum position and acquired pellicle on Candida albicans biofilm

The purpose of this study was to evaluate the influence of the substratum position and the saliva acquired pellicle (AP) on Candida albicans biofilm development. Poly(methylmethacrylate) (PMMA) disks were fabricated and randomly allocated to experimental groups: HNP (disks placed in a horizontal position and uncoated by pellicle), VNP (disks placed in a vertical position and uncoated by pellicle), HCP (disks placed in a horizontal position and coated by pellicle), and VCP (disks placed in a vertical position and coated by pellicle). Disks were placed in a 24-well plate and a suspension of 107 cells/mL of Candida albicans was added to each well for biofilm development. The plates were aerobically incubated at 35°C. The biofilms were evaluated at 1.5 (adhesion time point), 24, 48, 72, and 96 hours. The number of viable cells was quantified in terms of the colony-forming units per milliliter (CFU/mL). Metabolic activity was measured by the XTT assay. The biofilm structure was analyzed by scanning electron microscopy. The data were analyzed by three-way ANOVA followed by Tukey's test, with significance set at 5%. The vertical groups showed less biofilm formation and lower metabolic activity than the horizontal groups (p< 0.05). Significant differences in cell viability and metabolic activity were observed between the adhesion and other time points (p< 0.05), but these variables were not affected by the presence of the pellicle (p > 0.05). It can be concluded that the substratum position influenced biofilm development.

Effectiveness of different obturation techniques in surpassing the ledge formed in simulated curved canals

Aim: To compare the effectiveness of different obturation techniques in surpassing the ledgeformed in simulated curved root canals. Methods: Eighty acrylic-resin blocks with curved canalswere instrumented with Gates-Glidden drills to simulate a ledge formation. Then, a K-File #10 wasused for trying to surpass the deviation, and the blocks that permitted surpassing were rejected.The remaining blocks were divided into 4 groups according to the obturation technique: lateralcondensation, Tagger’s Hybrid technique, Thermafil and System B. The blocks had their imagesdigitalized using a scanner before and after the obturation procedures. The images were analyzedwith Image Tool 3.0 software. Statistical analysis was performed by one-way ANOVA at a significantlevel of 5%. Results: The System B resulted in the highest obturated area (p<0.001). Therewere no significant differences between the Tagger’s Hybrid technique and Thermafil systemregarding the effectiveness in surpassing ledge (p>0.05). The lateral condensation resulted in theworst ability in filling the ledge space (p<0.001). Conclusions: Within the limitations of this study,it was possible to conclude that techniques using heat condensation or gutta-perchathermoplastification were more effective in surpassing the ledge formed in curved canals than thelateral condensation.

Multidisciplinary Therapy of Extensive Oligodontia: A Case Report

Oligodontia is a rare congenital disorder consisting in the absence of six or more teeth. This case report describes a multidisciplinary treatment approach for a 12-year-old male with absence of 11 permanent teeth. Prior to any procedure, all primary teeth were scheduled for extraction due to poor crown-to-root ratio. The treatment plan comprised two phases: 1. orthodontic and speech therapy aimed at overbite and anterior open bite adjustment, as well as tongue position improvement; and 2. prosthetic treatment by insertion of removable temporary partial dentures. The multidisciplinary treatment involving orthodontics, speech and prosthetic therapies have reestablished the masticatory function and aesthetics, allowing the patient to achieve greater self-esteem and better social acceptance.

Resumo A oligodontia é uma doença rara, congênita, caracterizada pela ausência de seis ou mais dentes. Este relato de caso descreve uma abordagem terapêutica multidisciplinar de um adolescente de 12 anos de idade com ausência de 11 dentes permanentes. Antes de qualquer procedimento, todos os dentes decíduos foram extraídos devido à pobre relação coroa-raiz. O plano de tratamento foi constituído por duas fases: 1. terapia ortodôntica e fonoaudiológica com o objetivo de ajuste de sobre-mordida e mordida aberta anterior, bem como melhoria da posição da língua, e 2. tratamento reabilitador protético através da instalação de próteses parciais removíveis provisórias. A abordagem multidisciplinar envolvendo os tratamentos ortodônticos, fonoaudiológico e protético reestabeleceram a função mastigatória e a estética, melhorando a autoestima e aceitação social do paciente. .

Exopolysaccharide matrix of developed candida albicans biofilms after exposure to antifungal agents

This study aimed to evaluate the effects of fluconazole or nystatin exposure on developed Candida albicans biofilms regarding their exopolysaccharide matrix. The minimal inhibitory concentration (MIC) against fluconazole or nystatin was determined for C. albicans reference strain (ATCC 90028). Poly(methlymethacrylate) resin (PMMA) specimens were fabricated according to the manufacturer's instructions and had their surface roughness measured. Biofilms were developed on specimens surfaces for 48 h and after that were exposed during 24 h to fluconazole or nystatin prepared in a medium at MIC, 10 x MIC or 100 x MIC. Metabolic activity was evaluated using an XTT assay. Production of soluble and insoluble exopolysaccharide and intracellular polysaccharides was evaluated by the phenol-sulfuric method. Confocal laser scanning microscope was used to evaluate biofilm architecture and percentage of dead/live cells. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. The presence of fluconazole or nystatin at concentrations higher than MIC results in a great reduction of metabolic activity (p<0.001). At MIC or 10 x MIC, fluconazole showed high amounts of intracellular polysaccharides (p<0.05), but did not affect the exopolysaccharide matrix (p>0.05). The exposure to nystatin also did not alter the exopolysaccharide matrix at all the tested concentrations (p>0.05). Biofilm architecture was not affected by either of the antifungal agents (p>0.05). Nystatin promoted higher proportion of dead cells (p<0.05). It may be concluded that fluconazole and nystatin above the MIC concentration reduced the metabolic activity of C. albicans biofilms; however, they were not able to alter the exopolysaccharide matrix and biofilm architecture.

Este estudo avaliou o efeito da exposição de fluconazol ou nistatina a biofilmes de Candida albicans desenvolvidos, considerando a matriz de polissacarídeos extracelulares. Inicialmente uma cepa referência de C. albicans (ATCC 90028) foi submetida ao teste de concentração inibitória mínima (CIM) utilizando-se o fluconazol ou nistatina como agentes antifúngicos. Após, espécimes foram confeccionados em resina acrílica de polimetilmetacrilato (PMMA) de acordo com as recomendações do fabricante e tiveram sua rugosidade de superfície padronizada. Após, biofilmes de C. albicans foram desenvolvidos na superfície dos espécimes durante 48 h. Em seguida, os biofilmes foram expostos a fluconazol ou nistatina nas concentrações de CIM, 10 x CIM ou 100 x CIM, por 24 h. A atividade metabólica dos biofilmes foi avaliada pelo teste de XTT. A produção de polissacarídeos extracelulares solúveis e insolúveis, bem como dos polissacarídeos intracelulares foi avaliada pelo método fenol-sulfúrico. A arquitetura dos biofilmes e proporção de células vivas e mortas foi investigada utilizando-se microscopia confocal a laser. Os resultados foram analisados por ANOVA seguido do teste de Tukey, utilizando-se o nível de significância de 5%. A presença do fluconazol ou nistatina em concentrações maiores que CIM resultaram em uma redução significativa da atividade metabólica (p<0,001). Nas concentrações de CIM e 10 x CIM, biofilmes expostos ao fluconazol apresentaram quantidades significativas de polissacarídeos intracelulares (p<0,05), enquanto não houve alterações na quantidade de polissacarídeos extracelulares (p>0,05). A presença de nistatina também não alterou a matriz de polissacarídeos extracelulares em todas as concentrações investigadas (p>0,05). A arquitetura dos biofilmes não foi afetada por ambos os agentes antifúngicos, em qualquer concentração testada (p>0,05). A nistatina apresentou maior proporção de células mortas (p<0,05). Conclui-se que tanto para o fluconazol quanto para a nistatina, concentrações maiores que CIM reduziram a atividade metabólica dos biofilmes de C. albicans; no entanto, tais concentrações não alteraram a matriz de polissacarídeos extracelulares nem a arquitetura dos biofilmes.

Poly (Methyl Methacrylate) absorption and releasing of nystatin and fluconazole / Absorção e liberação de nistatina e fluconazol por polimetilmetacrilato

Objectives: The aim of this study was to verify if there are poly (methyl methacrylate) (PMMA) absorptionand releasing of nystatin (NYS) and fluconazole (FLZ) after simulated treatment of oral candidosis. Materialsand methods: Specimens (30 × 25 × 5 mm) prepared with PMMA polymerized by hot water bath or microwaveenergy were immersed into NYS (3.12 μg/mL), FLZ (2.56 μg/mL) or deionized water (control) during14 days at 35 ± 2 °C. After treatment simulation, specimens were immersed into distilled water during 3, 7, 10and 14 days. The immersion liquid was changed after each analysis. Higher performance liquid chromatographywas used in order to detect antifungal compounds. In order to determine if there was surface depositionof drugs on PMMA resin, specimens were analyzed with electronic microscopy (SEM). Results: None of theantifungal agents was released from the PMMA resins. Conclusion: Within the limitations of this study, itcould be concluded that PMMA resins had no drug absorption with posterior release.

Objetivos: O objetivo deste estudo foi verificar se o poli (metil metacrilato) (PMMA) é capaz de absorver e liberar nistatina (NYS) e fluconazol (FLZ) após simular um tratamento para candidose oral. Materiais e métodos:Espécimes (30 × 25 × 5 mm) foram preparados em resina de PMMA por banho de água quente ou energia demicro-ondas e, em seguida, imersos em solução contendo NYS (3.12 μg/mL), FLZ (2.56 μg/mL) ou água deionizada(controle) durante 14 dias a 35 ± 2 °C. Após a simulação de tratamento, os espécimes foram imersos em água destilada durante 3, 7, 10 e 14 dias. O líquido de imersão foi trocado após cada análise. Cromatografia líquida de alta performance foi utilizada para detectar a presença dos agentes antifúngicos. Para determinar se houve deposição dos agentes antifúngicos na superfície de PMMA, os espécimes foram analisados por microscopia eletrônica de varredura(MEV). Resultados: Não houve liberação de agentes antifúngicos dos espécimes. Conclusão: Considerando as limitações deste estudo, pode-se concluir que a resina de PMMA não absorve ou libera agentes antifúngicos.

Influence of female hormonal fluctuation on maximum occlusal force

Hormonal fluctuations during the menstrual cycle may influence on muscular tensions and probably alter occlusal force. The aim of this study was to evaluate whether hormonal levels affect maximum occlusal force (MOF) of healthy women throughout the different phases of the menstrual cycle. Sixty complete dentate subjects who were not under use of oral contraceptives were selected to participate in this study. MOF was bilaterally evaluated on the molar region, during 3 complete menstrual cycles, using 5.65 mm-wide sensors. Measurements were carried out during each of the following menstrual cycle phases: menstrual, follicular, periovulatory and luteal, presumed by ovulation test. Data were analyzed by one-way ANOVA and Tukey-Kramer test (p<0.05). Comparisons among menstrual cycle phases showed no differences on MOF (p=0.27). Under the conditions of this study, it may be concluded that hormonal fluctuations during the menstrual cycle do not affect MOF of a sample of healthy women.

As flutuações hormonais durante o ciclo menstrual podem influenciar as tensões musculares e possivelmente alterar a força oclusal. O objetivo deste estudo foi avaliar se os níveis hormonais afetam a força máxima oclusal (FMO) de mulheres saudáveis durante as diferentes fases do ciclo menstrual. Sessenta pacientes completamente dentadas que não usavam contraceptivos orais foram selecionadas para participar neste estudo. FMO foi avaliada bilateralmente na região dos molares, durante 3 ciclos menstruais completos, utilizando sensores de 5,65 mm de espessura. As mensurações foram realizadas durante cada fase do ciclo menstrual: menstrual, folicular e lútea periovulatória, identificadas por teste ovulatório. Os dados foram analisados por ANOVA um critério seguido do teste de Tukey-Kramer (p<0,05). As comparações entre as fases do ciclo menstrual não apresentaram diferenças na FMO (p=0,27). Segundo as condições deste estudo, pode-se concluir que as flutuações hormonais durante o ciclo menstrual não afetaram a FMO de mulheres saudáveis.

Influence of immersion time of denture cleansers on the surface roughness of resilient denture liners / Influência do tempo de imersão de limpadores químicos sobre a rugosidade de superfície de reembasadores resilientes para próteses removíveis

PURPOSE: The objective of this study was to evaluate the effect of different immersion times in denture cleansers on surface roughness (SR) of two resilient denture liners (RDL) after the cleanliness of Candida albicans biofilm. METHODS: Poly(methyl methacrylate) (PMMA) resin discs (10x1.5 mm) were relined with a 1.5 mm layer of RDL (PMMA or silicone-based). The initial SR of each specimen was measured and C. albicans biofilm was developed for 48 h. Subsequently, the discs were randomly assigned for one of four cleansing treatments (n=8): two alkaline peroxide (soaking for 3 or 15 min), 0.5 percent sodium hypochlorite (10 min) or distilled water as control (15 min). After the treatments, the SR was measured again. Data were analyzed by ANOVA and the Tukey post-hoc test (α=0.05) RESULTS: No differences were found between the cleansing treatments evaluated (P>0.05). The PMMA-based liner exhibited higher SR than silicon-based (P<0.001); however, both liners showed higher SR after the reatments compared with the baseline values (P<0.001). CONCLUSION: Within limitations of this study, it can be concluded that the surface roughness of RDL increased after the immersion in denture cleansers, independently of the time of immersion.

OBJETIVO: O objetivo deste estudo foi avaliar o efeito de diferentes tempos de imersão em limpadores químicos sobre a rugosidade de superfície ( RS)de reembasadores resilientes após a simulação da limpeza de biofilmes de Candida albicans. METODOLOGIA: Discos (10x1,5 mm) de poli(metilmetacrilato) (PMMA) foram cobertos com uma camada de 1,5 mm de reembasador resiliente (a base de PMMA ou silicone). A RS inicial de cada espécime foi mensurada e biofilmes de C. albicans desenvolvidos por 48 h. Em seguida, os espécimes foram submetidos aleatoriamente a um dos tratamentos (n=8): duas soluções alcalinas a base de peróxido (imersão por 3 ou 15 min), hipoclorito de sódio a 0.5 por cento (10 min) ou água destilada como grupo controle (15 min). Após o tratamento, a RS foi mensurada novamente. Os resultados foram analisados por ANOVA e teste Tukey (α=0,05). RESULTADOS: Não houve diferença estatística entre os tratamentos (P>0,05). O reembasador a base de PMMA apresentou maior RS que os de silicone (P<0,001); entretanto, ambos apresentaram um aumento da RS após os tratamentos (P<0,001). CONCLUSÃO: Dentro das limitações deste estudo, conclui-se que a RS dos reembasadores resilientes aumenta após a imersão em limpadores químicos, independentemente do tempo de imersão.

Mineral trioxide aggregate as root canal filing material: comparative study of physical properties / MTA como cimento endodôntico: estudo comparativo de propriedades físicas

Purpose: This study evaluated some physical properties of two commercial MTA cements regarding it use as root canal filling material. Methods: The compression strength (CS) of the evaluated materials was performed after 21 hours or 14 days of water immersion. The materials´ radiopacity (RD) was measured according to aluminum thickness. Regarding setting time (ST), both initial and final times were measured. The solubility (SB) was calculated according to percentage of lost mass after water storage. The pH measurement was performed in three different times (initial, 1 and 24 hours) of water storage. All tests were performed according to ISO 6876-2:2001. Results: Both cements showed that CS and pH were as in accordance with ISO standard. The two cements exhibited RD values higher than the equivalent limit of 3 mm-aluminum. Both materials exhibited SB values within the recommended limit of 3%. ST and pH also are in accordance with ISO 6876-2:2001. Additional SEM surface evaluation showed both amorphous and crystalline phase for both cements. Conclusion: It is possible to conclude that all evaluated materials are in accordance with ISO standard, allowing its use as root canal filling material.

Objetivo: Este estudo avaliou as propriedades físicas de dois cimentos MTA disponíveis comercialmente. Metodologia: A resistência a compressão (CS) dos materiais avaliados foi realizada após 21 horas e 14 dias de imersão em água. A avaliação da radiopacidade (RD) dos materiais foi mensurada em função de espessura de alumínio. Com relação à propriedade de tempo de presa (ST), tanto os tempos de presa inicial e final foram mensurados. A solubilidade foi calculada em função da percentagem de massa perdida após armazenamento em água. Os valores de pH foram mensurados em três diferentes tempos (inicial, 1 e 24 horas) de armazenamento em água. Todos os testes foram realizados de acordo com a normaISO 6876-2:2001. Resultados: Ambos os materiais apresentaram valores de CS e pH em acordo com os valores da norma ISO. Os dois cimentos apresentaram RD superiores ao limite de 3 mm de alumínio. Ambos os materiais mostraram resultados de SB inferiores ao limite de 3%. ST e pH também estão de acordo com a norma ISO 6876-2:2001. Adicionalmente foram avaliadas as superfícies dos materiais por MEV, e ambos apresentaram fases estruturais amorfas e cristalinas. Conclusão: Concluiu-se que ambos os materiais avaliados estão de acordo com as normas ISO, permitindo o seu uso como material de preenchimento de canais radiculares.

Long-term efficacy of denture cleansers in preventing Candida spp. biofilm recolonization on liner surface

This study evaluated the long-term efficacy of denture cleansers against Candida spp. biofilm recolonization on liner surface. Specimens were fabricated of a poly(methyl methacrylate)-based denture liner and had their surface roughness evaluated at baseline and after cleansing treatments. C. albicans or C. glabrata biofilms were formed on liner surface for 48 h, and then the specimens were randomly assigned to one of cleaning treatments: two alkaline peroxides (soaking for 3 or 15 min), 0.5 percent sodium hypochlorite (10 min) or distilled water (control; 15 min). After the treatments, the specimens were sonicated to disrupt the biofilm, and residual cells were counted (cell/mL). Long-term effectiveness of the cleaning processes was determined by submitting a set of cleaned specimens to biofilm growth conditions for 48 h followed by estimation of cell counts. The topography of specimens after cleaning treatments was analyzed by SEM. Data were analyzed by ANOVA and Tukey's test (α; = 0.05). Results of cell count estimation showed significant differences in cleanliness among the treatments (p < 0.001), and it could be observed by SEM. However, no significant difference (p > 0.05) was observed among the Candida species regarding the recolonization condition. Alkaline denture cleansers showed similar cleaning performance and both differed from the control (p < 0.001). Sodium hypochlorite was the only treatment that removed biofilm efficiently, since no viable cells were found after its use. In conclusion, alkaline peroxide denture cleansers were not effective in removing Candida spp. biofilm from denture liner surfaces and preventing biofilm recolonization.

Preload loss and bacterial penetration on different implant-abutment connection systems

Preload loss can favor the occurrence of implant-abutment interface misfit, and bacterial colonization at this interface may lead to implant failure. The aim of this study was to evaluate the preload loss and bacterial penetration through the implant-abutment interface of conical and external hexagon connection systems subjected to thermal cycling and mechanical fatigue (TM). Four different implant-abutment connection systems were evaluated (n=6): external hexagon with universal post, Morse taper with universal post, Morse taper with universal post through bolt, and locking taper with standard abutment. The assemblies (implant-abutment) were subjected to a thermal cycling regimen (1,000 cycles of 5°C and 55°C) and to mechanical fatigue (1.0 million cycles, 1.0 Hz, 120 N). The assemblies were immersed in Tryptic Soy + Yeast Extract broth containing Streptococcus sanguinis and incubated at 37°C and 10 percent CO2 for 72 h. Detorque values were recorded. The bacterial penetration was assessed and the abutments were observed by scanning electron microscopy. The preload data were analyzed statistically by two-way ANOVA and Tukey’s test at 5 percent significance level. All screw abutment systems showed significantly higher (p<0.05) detorque values when subjected to TM and all conical systems presented bacterial penetration. The results show no relationship between the preload loss and the bacterial penetration.

A perda da pré-carga pode favorecer o desajuste da interface implante-pilar e a colonização bacteriana nesta interface pode levar a perda de implantes. O objetivo deste estudo foi avaliar a perda de pré-carga e a infiltração bacteriana através da interface implante-pilar de sistemas de conexão cônica e hexágono externo, submetidos à ciclagem térmica e fadiga mecânica (CF). Quatro diferentes sistemas de conexão implante-pilar foram avaliados (n=6): hexágono externo com munhão universal, cone Morse com munhão universal, cone Morse com munhão universal parafuso passante e cônica justaposição com pilar padrão. Os espécimes (implante-pilar) foram submetidos à ciclagem térmica (1000 ciclos a 5°C e 55°C) e à fadiga mecânica (1,0 milhão de ciclos, 1,0 Hz, 120 N). Os espécimes foram imersos em caldo Tryptic Soy + Yeast Extract contendo Streptococcus sanguinis e incubados a 37°C e 10 por cento de CO2 por 72 h. Os valores de destorque foram registrados. A infiltração bacteriana foi avaliada e os pilares foram observados por microscopia eletrônica de varredura. Os dados de pré-carga foram analisados estatisticamente por ANOVA a dois critérios e teste de Tukey, com nível de significância de 5 por cento. Todos os sistemas de pilares parafusados apresentaram maiores valores de destorque quando submetidos à CF (p<0,05) e todos os sistemas cônicos apresentaram infiltração bacteriana. Os resultados mostram que não houve relação entre a perda da pré-carga e a infiltração bacteriana.

Microstructural characterization of Ni-Cr-Mo-Ti and Ti-6Al-4V alloys used in prosthetic abutments / Caracterização microestrutural das ligas Ni-Cr-Mo-Ti e Ti-6Al-4V utilizadas para pilares de próteses

Purpose: Titanium alloys are commonly used for prosthetic abutments fabrication, but these alloys present high cost and difficult handling. Alternative Ni-Cr alloys with Mo and Ti combination have been proposed. This study compared the alloys Ti-6Al-4V and Ni-Cr-Ti-Mo by analyzing their surface properties such as hardness, morphology and microstructural characterization. Methods: Five discs (5 x 2 mm) of commercially Ti-6Al-4V and Ni-Cr-Ti-Mo alloys were used to evaluate Vickers hardness by hardness micro indentation test. The same specimens were analyzed by scanning electron microscopy (SEM) regarding surface morphology and subjected to a metallographic analysis of the microstructure by optical microscopy. Data on surface hardness were analyzed using one-way ANOVA followed by Tukey test (α = 0.05). Results: The Ni-Cr-Mo-Ti alloy showed significantly higher Vickers hardness (kg/mm2) values (452.2 ± 3.9) than the Ti-6Al-4V alloy (375.7 ± 15.2). The surface morphology evaluated by SEM revealed differences between the alloys. Metallographic analyses, for both alloys, showed a two-phase equilibrium microstructure, with the presence of e α + ß phase for Ti-6Al-4V; and gamma (γ) primary phase and gamma-prime (γ´) as a second phase for Ni-Cr-Mo-Ti. Conclusion: It can be concluded that both alloys present the requirements to be used in prosthetic abutments.

Objetivo: As ligas de titânio são comumente usadas para a fabricação de componentes protéticos, entretanto apresentam alto custo e dificuldade de manuseio laboratorial. Ligas alternativas a base de Ni-Cr combinadas com Mo e Ti também tem sido propostas com o mesmo objeto. Este estudo comparou as ligas Ti-6Al-4V e Ni-Cr-Ti-Mo pela análise de suas propriedades de superfície como dureza, morfologia e caracterização da microestrutura.Metodologia: Cinco discos (5 × 2 mm) das ligas Ti-6Al-4V e Ni-Cr-Ti-Mo foram utilizados para a avaliação da dureza Vickers, análise de morfologia de superfície por meio da microscopia eletrônica de varredura (MEV) e análise da microestrutura pela análise metalográfica. Os dados da dureza de superfície foram analisados pela Análise de Variância a um nível seguida do teste de Tukey (α = 0,05). Resultados: A liga Ni-Cr-Mo-Ti apresentou os maiores valores de dureza Vickers (kg/mm2) (452,2 ± 3,9) comparada a liga Ti-6Al-4V (375,7 ± 15,2) A morfologia de superfície avaliada por MEV revelou características distintas entre as ligas. A análise metalográfica para ambas as ligas mostrou uma microestrutura com equilíbrio de duas fases, com a presença de fase α + ß para Ti-6Al-4V; e fase gamma primária (γ) e fase gamma-prime (γ') como secundária para Ni-Cr-Mo-Ti. Conclusão: Ambas as ligas podem ser utilizadas para fabricação de pilares protéticos.

Improvement of XTT assay performance for studies involving Candida albicans biofilms

2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay has been used to study Candida biofilm formation. However, considering that the XTT reduction assay is dependent on cell activity, its use for evaluating mature biofilms may lead to inaccuracies since biofilm bottom cell layers tend to be relatively quiescent at later stages of biofilm formation. The aim of this study was to improve XTT reduction assay by adding glucose supplements to the standard XTT formulation. Candida albicans ATCC 90028 was used to form 24-, 48- and 72-h biofilms. The oxidative activity at 90, 180 and 270 min of incubation was evaluated. The control consisted of standard XTT formulation without glucose supplements, and was modified by the addition of 50, 100 and 200 mM of glucose. The XTT assay with 200 mM glucose showed more accurate and consistent readings correlating with biofilm development at 24, 48 and 72 h. Biofilm growth yield after 180 min incubation, when evaluated with the 200 mM glucose supplemented XTT, produced the most consistent readings on repetitive testing. It may be concluded that glucose supplementation of XTT could minimize variation and produce more accurate data for the XTT assay.

O teste de redução do 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) tem sido utilizado para mensurar o desenvolvimento de biofilmes de Candida. Contudo, a reação de XTT é dependente da atividade celular e o seu uso para biofilmes maduros pode ser questionado, considerando que diferentes camadas celulares têm atividade metabólica diferenciadas. O objetivo deste estudo foi avaliar se a adição de glicose à formula de XTT diminuiria a variabilidade na mensuração da atividade metabólica. Biofilmes de Candida albicans ATCC 90028 com tempos de crescimento de 24, 48 e 72 h foram utilizados. Para avaliar o melhor tempo de incubação do XTT, este foi mantido a temperatura de 37 °C, em tempos de 90 180 e 270 min. A fórmula padrão do teste XTT (controle) foi modificada com a adição de 50, 100 e 200 mM de glicose para os grupos experimentais. Os melhores resultados para a incubação foi observado com tempo de 180 min e para a suplementação de glicose à concentração de 200 mM (p<0.001). Concluiu-se que a incubação de 180 min utilizando a suplementação de 200 mM de glicose apresenta resultados de atividade metabólica celular com a menor variação para o estudo de biofilmes de Candida albicans.

Effects of nystatin, fluconazole and propolis on poly (methyl methacrylate) resin surface

The prevalence of candidosis in denture wearers is as well established as its treatment with antifungal agents (AAs). However, little research has been done regarding the effects of AAs on denture base surfaces. Therefore, the aim of this study was to evaluate the effects of fluconazole (FLU), nystatin (NYS) and propolis orabase gel (PRO) on poly (methyl-methacrylate) (PMMA) surfaces. Deionized water and orabase gel without any active component were used as control groups. Conventional heat-polymerized (Clássico) and microwave-polymerized (Onda Cryl) acrylic resins were used. After polymerization, the specimens were polished and had their surfaces evaluated for roughness, free energy and Knoop hardness. Subsequently, specimens were immersed in AAs and controls for 14 days at 35±2 °C and all variables were measured again. Data were analyzed statistically by 2-way ANOVA followed by Tukey's test ( α=0.05). Roughness results showed similar behavior for both PMMA resins, with PRO reaching the highest values and differing significantly from the other AAs (p<0.05). No statistically significant differences (p>0.05) were found between the two PMMA resins or between NYS and FLU as regards surface free energy. In conclusion, PRO was able to induce changes in PMMA surface properties, such as roughness, which could be related to microbial adhesion.

A alta prevalência da candidose em usuários de prótese dental removível e a sua terapêutica com agentes antifúngicos (AA) está estabelecida. Contudo, o efeito dos AA sobre a superfície da resina de poli(metil-metacrilato) (PMMA) ainda não foi estudada. Assim, objetivou-se avaliar o efeito do fluconazol (FLU), nistatina (NYS) e gel orabase de própolis (GO) sobre a superfície de PMMA. Água deionizada e GO sem princípio ativo foram utilizadas como controles. Espécimes fabricados com PMMA polimerizada em banho de água ou com energia de microondas receberam acabamento e polimento e tiveram a rugosidade de superfície (RS), energia livre de superfície (ELS) e dureza Knoop (DK) mensuradas. Os tratamentos de superfície foram obtidos pela imersão dos espécimes nos AA durante 14 dias. Os resultados obtidos foram analisados por ANOVA para dois fatores e para a comparação, entre tratamentos e resinas, o teste de Tukey (α=0,05) foi utilizado. Os resultados mostraram que ambas as resinas aumentaram RS e ELS, mas não diferiram entre si (p>0,05). Os grupos tratados com própolis mostraram valores maiores de RS e diferente dos demais AAs (p<0,05). Com relação a rugosidade e energia livre de superfície não foram encontradas diferenças entre as PMMAs e entre FLU e NYS. Concluiu-se que a própolis induziu modificações na superfície de PMMA aumentando a rugosidade, fator que poderá facilitar a adesão de microrganismos.

Evaluation of surface characteristics of Ti-6Al-4V and Tilite alloys used for implant abutments

The aim of this study was to evaluate surface free energy (SFE), surface roughness (SR) and surface hardness (SH) of two commercially available materials for fabricating dental implant abutments. In addition, the specimens were investigated by scanning electron microscopy (SEM) to determine the surface morphology. Twenty five discs (5 x 2 mm) of Ti-6Al-4V and Tilite (Ni-Cr-Ti) alloys were used in this study. Surface free energy was determined by the contact angle formed between a drop of distilled, deionized water and the surface of the specimen of each material. The surface roughness was measured with a mechanical profilometer and the surface hardness was evaluated by means of the Vickers hardness micro indentation test. SFE, SR and SH data were analyzed using one-way ANOVA (p < 0.05). Statistical differences (p < 0.05) were found between Ti-6Al-4V (36.2 erg.cm-2; 0.2 æm) and Tilite (30.9 erg.cm-2; 0.16 æm) for SFE and SR. However, the differences between the surface hardness values of Ti-6Al-4V (325.0 kg/mm²) and Tilite (324.3 kg/mm²) were not statistically significant (p > 0.05). Evaluations by SEM revealed different surface morphology. Within the limits of this study, it can be concluded that the Ti-6Al-4V and Tilite alloys showed differences in surface properties, except for surface hardness, suggesting that both alloys may be considered appropriate for producing abutments. Further studies are, however, necessary to elucidate the biological responses to implant abutments made with these alloys.

O objetivo deste estudo foi avaliar a energia livre de superfície (ELS), rugosidade superficial (RS) e dureza de superfície (DS) de dois materiais disponíveis comercialmente para fabricação de "abutments" de implante. Em acréscimo, os espécimes foram investigados por microscopia eletrônica de varredura (MEV) para determinar a morfologia de superfície. Vinte e cinco discos de ligas de Ti-6Al-4V e Tilite (Ni-Cr-Ti) (5 x 2 mm) foram usados neste estudo. A energia livre de superfície foi determinada pela mensuração do ângulo de contato formado entre uma gota de água destilada e deionizada e a superfície do espécime para cada material. A rugosidade superficial foi mensurada com uso de um rugosímetro e a dureza de superfície foi avaliada por meio do teste de microdureza Vickers. Os dados foram analisados usando Análise de variância (P < 0,05). Foram encontradas diferenças significantes (P < 0,05) para os valores de ELS e RS entre Ti-6Al-4V (36,2 erg.cm-2; 0,2 æm) e Tilite (30,9 erg.cm-2; 0,16 æm). Entretanto, os valores de dureza de superfície não foram diferentes para ambos os materiais (Ti-6Al-4V - 325,0 kg/mm² e Tilite - 324,3 kg/mm²) (P > 0,05). A análise topográfica dos materiais pela MEV revelou superfícies diferentes. Dentro das limitações deste estudo, concluiu-se que as ligas de Ti-6Al-4V e Tilite mostraram diferenças nas propriedades de superfícies, exceto dureza, sugerindo que ambas as ligas são adequadas para a confecção de "abutments". Entretanto, estudos são necessários para evidenciar as respostas biológicas aos "abutments" de implantes confeccionados com essas ligas.