Effects of cigarette smoke on color, roughness and gloss of high-viscosity bulk-fill resin composites.

PURPOSE: To evaluate the effect of cigarette smoke (CS) on color, roughness and gloss of bulk-fill resin composites. METHODS: Resin discs (10 x 2 mm) were made for resin composites (n= 10) : Filtek Z250XT (control), Filtek One Bulk Fill (FOBF), Tetric N-Ceram Bulk-Fill (TBF) and Aura Bulk-Fill (ABF). The color ( ΔL*, Δa*, Δb*, ΔE and ΔE00), roughness (Ra) and gloss analyses were performed at the baseline and after CS exposure (10 packs of cigarettes - Marlboro Red). The data were analyzed with repeated measures ANOVA and Tukey's test for Ra and gloss; and one-way ANOVA and Tukey's test for ΔL*, Δa*, Δb*, ΔE and ΔE00 ( α= 0.05). RESULTS: For ΔL*, all groups presented reduced luminosity and all bulk-fill resin composites differed statistically from the control (P< 0.05). ABF presented greater variation of ΔL*, differing statistically from all resin composites (P< 0.05). For ΔE and ΔE00, all bulk-fill resin composites showed greater staining, differing statistically from the control, which presented lower values. For Ra, after CS, only ABF presented a decrease, differing statistically from baseline (P< 0.05). After CS smoke, all groups presented gloss increase, statistically different from the baseline (P< 0.05), and when compared among resin composites, no difference was found. CLINICAL SIGNIFICANCE: Bulk-fill resin composites are more prone to staining by cigarette smoke when compared to the conventional microhybrid resin composites.

Effect of Heavy Metals Contamination from Cigarette Smoke on Sound and Caries-Like Enamel.

In this study, we sought to evaluate the influence of cigarette smoke and pH cycling on the chemical composition and surface/cross-sectional enamel microhardness. A total of 40 dental blocks obtained from bovine incisors were divided into four groups (n=10): no treatment (control); exposure to cigarette smoke (CS); exposure to pH cycling (PC); and exposure to cigarette smoke and pH cycling (CS-PC). The samples were analyzed by synchrotron radiation micro X-ray fluorescence, bench mode X-ray fluorescence, as well as surface microhardness (SMH) and cross-sectional microhardness (CSMH) testing. The SMH results were submitted to analysis of variance (ANOVA) and Tukey's test. The CSMH results were evaluated using split-plot ANOVA and Tukey's test. A high amount of Cd and Pb and traces of Ni and As were observed in enamel and dentin after exposure to cigarette smoke (CS and CS-PC). The SMH and CSMH of CS were statistically higher when compared with the control. The PC and CS-PC showed lower SMH and CSMH. We conclude that exposure to cigarette smoke promoted heavy metal deposition in enamel/dentin. In addition, it increased the enamel microhardness but did not promote a protective effect on the in vitro development of caries. The clinical significance of this work is that there is significant bioaccumulation of heavy metals from cigarette smoke on the surface and in the enamel and dentin.

Influence of successive light-activation on degree of conversion and Knoop hardness of the first layered composite increment.

PURPOSE: To evaluate the influence of light-activation of second, third and fourth increments on degree of conversion (DC) and microhardness (KHN) of the top (T) and bottom (B) surface of the first increment. MATERIALS AND METHODS: Forty samples (n = 5) were prepared. In groups 1-4, after each increment light-activation (multiple irradiation), T and B of the first increment were measured in DC and KHN. In groups 5-8, only the first increment was made (single irradiation) and measurements of DC and KHN were taken at 15 min intervals. The light-activation modes were (XL) 500 mW/cm(2) × 38 s (G1/G5); (S) 1000 mW/cm(2) × 19 s (G2/G6), (HP) 1400 mW/cm(2) × 14 s (G3/G7); (PE) 3200 mW/cm(2) × 6 s (G4/G8). Data for DC and KHN were analyzed separately by using PROC MIXED for repeated measures and Tukey-Kramer test (α = 0.05). RESULTS: For KHN, B showed lower values than T. PE resulted in lower values of KHN in B surface. For single and multiple irradiations, T and B of first measurement showed the lowest KHN and the fourth measurement showed the highest, with significant difference between them. For single irradiation, first and second increments presented similar KHN, different from the third and fourth increment, which did not differ between them. For multiple irradiations, the second light-activation resulted in KHN similar to first, third and fourth increments. For DC, except QTH, T presented higher DC than B. CONCLUSION: The light-activation of successive increments was not able to influence the KHN and DC of the first increment.

Effect of in-office bleaching gels with calcium or fluoride on color, roughness, and enamel microhardness.

BACKGROUND: Commercial bleaching gels with remineralizing agents were developed to reduce the adverse effects of dental bleaching. The present study evaluated the effects on teeth of in-office bleaching gels containing 35-40% hydrogen peroxide (HP) with Calcium (Ca) or Fluoride (F). MATERIAL AND METHODS: Bovine enamel/dentin blocks (4x4x2.5 mm) were randomly divided into the following groups (n=12): no treatment (control); 35% HP (Whiteness HP, FGM); 35% HP with Ca (Whiteness HP Blue, FGM); 40% HP with F (Opalescence Boost, Ultradent). The specimens were analyzed for color (ΔL*, Δa*, Δb*, and ΔE), roughness (Ra), and Knoop microhardness (KHN). The color and KHN data were submitted to ANOVA and Tukey's test, while Ra values were analyzed using mixed models for repeated measures and Tukey-Kramer's test (α=0.05). RESULTS: The bleached groups did not exhibit statistical differences among them for color. For roughness, 35% HP provided a slight increase of Ra, which was statistically different from the control. For microhardness, 35% HP and 40% HP with F presented KHN values that were statistically lower from the control, while the 35% HP with Ca did not statistically differ from the control. CONCLUSIONS: The presence of Ca or F in bleaching gels did not interfere with bleaching efficacy. However, only the enamel exposed to the bleaching gel containing Ca obtained microhardness values similar to unbleached enamel. Key words:Hydrogen peroxide, tooth bleaching, tooth bleaching agents, laboratory research.

Effect of Dentin Pretreatment with Arginine on Microshear Bond Strength of Etch-and-Rinse or Self-Etch Adhesive Systems.

OBJECTIVE: The main purpose of this study was to evaluate the effect of dentin pretreatment with 8% arginine on the immediate and 6-month bond strength (BS) of adhesive systems and surface morphology of dentin. MATERIALS AND METHODS: Dentin bovine specimens (5 × 5 mm) were allocated into following pretreatments: without pretreatment (conventional technique, C) or exposure to arginine solution (A) for 5 minutes prior to tooth restoration. The adhesive procedure was performed using (n = 12): 3-step etch-and-rinse adhesive (Scotchbond Multipurpose-SBMP [C+SBMP and A+SBMP]); 2-step etch-and-rinse adhesive (Single Bond 2 - SB [C+SB and A+SB]); or 2-step self-etch adhesive (Clearfil SE Bond - CSEB [C+CSEB and A+CSEB]). After 24 hours, the composite resin restorations were evaluated immediately and after 6 months of water storage using a microshear test and fracture pattern. The dentin surface exposed to A was assessed by scanning electron microscopy (SEM). The immediate BS data were submitted to a two-way analysis of variance and Tukey's test, and the long-term BS results were analyzed using Kruskal-Wallis and Dunn tests (α = 0.05). RESULTS: There was a significant decrease in immediate and 6-month BS for the A+SB and A+CSEB groups, which differed statistically from the C group. The fracture pattern was predominantly adhesive for SB and CSEB adhesive for C and A. The SEM images presented a different conditioning pattern of the dentin exposed to A. CONCLUSION: The dentin pretreatment with arginine interfered negatively in the immediate and long-term BS of the simplified adhesive system. However, the SBMP adhesive was not affected by arginine pretreatment presenting the most satisfactory results.

PcsB Expression Diversity Influences on Streptococcus mitis Phenotypes Associated With Host Persistence and Virulence.

S. mitis is an abundant member of the commensal microbiota of the oral cavity and pharynx, which has the potential to promote systemic infections. By analyzing a collection of S. mitis strains isolated from the oral cavity at commensal states or from systemic infections (blood strains), we established that S. mitis ubiquitously express the surface immunodominant protein, PcsB (also called GbpB), required for binding to sucrose-derived exopolysaccharides (EPS). Immuno dot blot assays with anti-PcsB antibodies and RT-qPCR transcription analyses revealed strain-specific profiles of PcsB production associated with diversity in pcsB transcriptional activities. Additionally, blood strains showed significantly higher levels of PcsB expression compared to commensal isolates. Because Streptococcus mutans co-colonizes S. mitis dental biofilms, and secretes glucosyltransferases (GtfB/C/D) for the synthesis of highly insoluble EPS from sucrose, profiles of S. mitis binding to EPS, biofilm formation and evasion of the complement system were assessed in sucrose-containing BHI medium supplemented or not with filter-sterilized S. mutans culture supernatants. These analyses showed significant S. mitis binding to EPS and biofilm formation in the presence of S. mutans supernatants supplemented with sucrose, compared to BHI or BHI-sucrose medium. In addition, these phenotypes were abolished if strains were grown in culture supernatants of a gtfBCD-defective S. mutans mutant. Importantly, GtfB/C/D-associated phenotypes were enhanced in high PcsB-expressing strains, compared to low PcsB producers. Increased PcsB expression was further correlated with increased resistance to deposition of C3b/iC3b of the complement system after exposure to human serum, when strains were previously grown in the presence of S. mutans supernatants. Finally, analyses of PcsB polymorphisms and bioinformatic prediction of epitopes with significant binding to MHC class II alleles revealed that blood isolates harbor PcsB polymorphisms in its functionally conserved CHAP-domain, suggesting antigenic variation. These findings reveal important roles of PcsB in S. mitis-host interactions under commensal and pathogenic states, highlighting the need for studies to elucidate mechanisms regulating PcsB expression in this species.

Physical and photoelastic properties of bulk-fill and conventional composites.

PURPOSE: This study evaluated the influence of thickness increment on degree of conversion (DC), Knoop microhardness (KHN), and polymerization-shrinkage stress (PSS) by photoelasticity of three dental composites. METHODS: For DC and KHN, 45 samples were prepared and divided into nine groups (n=5), according to composite (microhybrid [Filtek Z250 - Z250], bulk-fill flowable [SureFil SDR Flow - SDR], and nanohybrid composite [N'Durance - NDU]) and increment thickness (1, 1.5, and 3 mm). PSS was measured by photoelastic analysis. Composites were placed into a photo-elastic model cavity and light-cured. DC and KHN data were subjected to two-way ANOVA and Bonferroni post hoc test. PSS results were qualitatively evaluated through Kruskal-Wallis test. RESULTS: SDR showed the highest DC values. At top and bottom surfaces, the highest KHN was obtained by Z250. Z250 showed higher PSS than SDR in 1.5 mm increments. NDU showed higher PSS than SDR in 3 mm increments. CONCLUSION: The bulk-fill composite demonstrated better DC and similar KHN and PSS in deeper layers compared to conventional composites. Bulk-fill composites may perform as well as conventional nanohybrid and microhybrid composites.

Esthetic smile rehabilitation of anterior teeth by treatment with biomimetic restorative materials: a case report.

BACKGROUND: In daily clinical practice, esthetics of anterior teeth is a common presenting complaint of patients. OBJECTIVE: This case report discusses the management of asymmetric smile associated with unsatisfactory extensive composite restorations and describes a clinical protocol using the direct composite resin for smile enhancement to restore the dental harmony of anterior teeth. METHODS: The treatment planning was based on a diagnostic wax-up and cosmetic mock-up. After clinical and patient approvals were obtained, the patient was subjected to direct and indirect restorative treatment. CONCLUSION: Nanocomposites are an effective alternative for anterior teeth restorations. Additionally, good planning enables satisfactory esthetic results, leading to the correction of an inappropriate axial inclination of incisors.

Effect of erosive challenge and cigarette smoke on dentin microhardness, surface morphology and bond strength / Efeito de desafios erosivos e fumaça de cigarro na microdureza, morfologia de superfície e resistência de união à dentina

Objective: This study aimed to evaluate the surface microhardness and morphology, as well as the microshear bond strength of a self-etching adhesive (Clearfil SE, Kuraray) to eroded dentin, exposed or not to cigarette smoke. Forty dental crowns were divided into 4 groups (n = 10): no treatment (control) (C); erosion (E); erosion + cigarette smoke exposure (ES); cigarette smoke exposure (S). Samples were prepared through third molars polishing until dentin exposure, followed by crown section. Erosive cycles were performed 5 times/day for 30 s at 60 min intervals. Cigarette smoke was produced with twenty cigarettes/day, during 5 days. Microhardness was evaluated initially and after the treatments. Microshear bond strength was tested after the treatments and dentin restoration with flow composite. Failure patterns and dentin morphology was evaluated by Scanning Electron Microscopy. Microshear bond strength data was submitted to two-way ANOVA, microharness test was adjusted by gamma distribution to be a non-parametric analyses (p=0.05), and surface morphology as qualitative analyses. Loss percentage of microhardness was observed only in groups submitted to erosion. Bond strength was statistically similar between all groups. The most prevalent failure pattern was of adhesive type. Morphological analysis of dentin showed obliterated tubules in groups submitted to cigarette smoke exposure. Cigarette smoke exposure did not promote any effect in the percentage of microhardness loss, as in sound dentin as in eroded dentin. Cigarette smoke, erosion, and association of both, did not alter the bond strength of self-etching adhesives to dentin. (AU)

Objetivo: Este estudo teve como objetivo avaliar a microdureza (% perda de dureza) e morfologia de superfície (MS), assim como a resistência de união (RU) de um adesivo autocondicionante (Clearfil SE, Kuraray) à uma dentina erodida, exposta ou não à fumaça de cigarro. Material e Métodos: Quarenta coroas dentais de terceiros molares foram seccionadas da raiz e polidas até a exposição dentinária, sendo aleatoriamente divididas em 4 grupos (n=10): sem tratamento (controle), erosão (E), erosão+ exposição a fumaça de cigarro (ES); exposição a fumaça de cigarro (S).O ciclo erosivo foi realizado 5 vezes/dia por 30s, com 60 minutos de intervalo entre eles. Os grupos ES e S foram exposto à fumaça de cigarro produzida por 20 cigarros/dia, durante 5 dias. A avaliação da microdureza foi realizada antes e após os tratamentos, enquanto a resistência da união por microcisalhamento foi realizada após os tratamentos Os padrões de fratura representativos e a MS dentinária foram avaliados por microscopia eletrônica de varredura (MEV). Os dados de RU foram analisados por ANOVA dois fatores, enquanto a análise de microdureza foi ajustada por distribuição gama por ser uma análise não-paramétrica (p=0.05). A MS foi analisada qualitativamente. Resultados: Os grupos expostos aos ciclos erosivos (E e ES) apresentaram % de perda de dureza significativamente menor que os grupos não expostos (Controle e S. aos ciclos erosivos (E e ES). Para RU, não houve diferença estatística significativa entre os grupos. O padrão de fratura mais observado foi do tipo adesivo, e através das imagens obtidas por MEV, observou-se a obliteração de túbulos dentinários no grupo exposto à fumaça de cigarro, enquanto os grupos submetidos aos ciclos erosivos (E e ES) apresentaram maior exposição e diâmetro de túbulos dentinários. Conclusão: A exposição à fumaça de cigarro não promove nenhum efeito quanto a perda de porcentagem de dureza dentinária, assim como em dentina erodida e saudável. A fumaça de cigarro, o processo erosivo, e a associação de ambos, não altera a resistência da união de adesivos autocondicionantes à dentina. (AU)

Avaliação in vitro da atividade de fosfolipase e proteinase de cepas de candida albicans isolada da cavidade bucal de pacientes diabéticos / In vitro evaluation of phospholipase and proteinase of candida albicans isolated from oral cavity of diabetic patients

Leveduras do gênero Candida são comuns na cavidade bucal e podem causar candidose na presença de fatores predisponentes, especialmente em paciente diabético, o qual é caracterizado por um aumento anormal da glicose no sangue. A manifestação da doença está relacionada a este conjunto de fatores locais, tais como a presença de próteses dentárias, pH salivar, fluxo salivar e tabaco. A redução da saliva é um dos principais fatores de risco para o aparecimento de infecção e o controle glicêmico inadequado causado por diabetes, em associação com todos estes fatores, pode aumentar a incidência de infecções. Os objetivos deste estudo foram: 1) isolar e identificar cepas de Candida albicans da mucosa bucal de pacientes diabéticos 2) avaliar os fatores de virulência: proteinase e fosfolipase. Amostras microbiológicas foram coletadas a partir de locais da mucosa bucal e semeadas em CHROMagar para posterior identificação de C. albicans por PCR. Foram realizados testes da atividade de proteinase e fosfolipase para todos os isolados de C. albicans. Neste estudo, 22 isolados foram identificados como C. albicans. Em relação às atividades de proteinases, todas as cepas de C. albicans foram capazes de produzir proteinase, enquanto que para fosfolipase, apenas 4,5% dos isolados não produziram esta exoenzima. Portanto, C. albicans presente na cavidade bucal de pacientes diabéticos tem potencial patogênico e pode participar de processos infecciosos e inflamatórios, causando lesões e invadindo os tecidos orais.

Candida yeasts are common in the oral cavity and can cause candidosis in the presence of predisposing factors, especially diabetes, which is characterized by an abnormal increasing in blood glucose concentration. The manifestation of the disease is related to a set of local factors such as the presence of dental prostheses, salivary pH, salivary flow and tobacco. The reduction in saliva is a major risk factor for the onset of infection and poor glycemic control caused by diabetes in association with all these factors further increases the incidence of candidosis. The objectives of this study were: 1) to isolate and identify Candida albicans strains from oral mucosa sites of diabetic patients 2) to evaluate the virulence factors: proteinase and phospholipase. Thus, microbial samples were collected from oral mucosa sites and seeded in CHROMagar for subsequent identification of C. albicans by PCR. For the phenotypic tests, all strains of C. albicans were evaluated for their proteinase and phospholipase productions. In this study, 22 isolates were identified as C. albicans. In regard to the proteinase activities, all strains of C. albicans were able to produce proteinase, while only 4.5% from those isolates were not able to produce phospholipase activity. In conclusion, C. albicans present in the oral cavity of diabetic patients is potentially pathogenic and can participate in infectious and inflammatory processes, causing injury and invading oral tissues.