Effect of different bonding protocols on degree of monomer conversion and bond strength between orthodontic brackets and enamel

Abstract The objective of the present study was to evaluate the effect of different surface treatments and polymerization protocols on the bond strength of brackets to enamel, and the degree of conversion of the bonding agents. 120 bovine crowns were embedded in acrylic resin blocks and sanded. Next, the blocks were randomly assigned into 12 groups. Metal brackets were bonded to enamel according to the "surface treatment" factor (A: Phosphoric Acid; ATxt: Phosphoric Acid + Transbond XT Primer®; Tse: Transbond Plus Self Etching Primer®; and SBU: Scotchbond Universal®) and "polymerization" factor (R20: Radii-Cal®/20 seconds; V20: Valo Cordless®/20 seconds; and V3: Valo Cordless®/3 seconds). All samples were stored for 6 months (water, 37ºC) and then subjected to a shear bond strength test (SBS). Bond failures were classified according to the Adhesive Remnant Index (ARI) and analyzed with the Kruskal-Wallis and Mann-Whitney tests (5%). Using the same factors, 120 resin discs were made to assess the degree of conversion (DC) of the monomer. Data from the SBS (MPa) and DC (%) were analyzed by analysis of variance (2 factors) and Tukey's test (5%). For the SBS, the factors "polymerization" (R20 = 8.1B; V20 = 13.2A; V3 = 5.2C, p = 0.0001) and "surface treatment" (A = 3.1C; ATxt = 13.6A; Tse = 12.3A; SBU = 6.3B, p = 0.0001) were statistically significant among groups. The highest adhesion value were found for the ATxt/V20 group (22.2A) and the lowest value for the A/R20 group (1.2E). Regarding ARI, score 2 was the most prevalent in groups A, ATxt, V20 and V3, while score 4 was the most prevalent in the Tse, SBU and R20 groups, with no significant difference between them (p = 1.0). Regarding DC, the factors "polymerization" (R20 = 66.6A; V20 = 58.4B; V3 = 45.1C, p = 0.0001) and "surface treatment" (A = 52B, ATxt = 59.7A, Tse = 51.4B, SBU = 63.8A, p = 0.0001) were statistically significant. Tse was more sensitive to the variations in polymerization protocols than the other surface treatments. Treatment A did not present suitable bond strength or degree of conversion.

Influence of antimicrobial solutions in the decontamination and adhesion of glass-fiber posts to root canals

AbstractObjective This study evaluated the effect of root canal disinfectants on the elimination of bacteria from the root canals, as well as their effect on glass-fiber posts bond strength.Material and Methods Fifty-three endodontically treated root canals had post spaces of 11 mm in length prepared and contaminated with E. faecalis. For CFU/ml analysis, eight teeth were contaminated for 1 h or 30 days (n=4). Teeth were decontaminated with 5% NaOCl, 2% CHX, or distilled water. As control, no decontamination was conducted. After decontamination, sterile paper points were used to collect samples, and CFU/ml were counted. For push-out, three groups were evaluated (n=15): irrigation with 2.5% NaOCl, 2% CHX, or sterile distilled water. A bonding agent was applied to root canal dentin, and a glass-fiber post was cemented with a dual-cured cement. After 24 h, 1-mm-thick slices of the middle portion of root canals were obtained and submitted to the push-out evaluation. Three specimens of each group were evaluated in scanning electron microscopy (SEM). Data were analyzed with one-way ANOVA and Dunnett’s T3 test (α=0.05).Results The number of CFU/ml increased from 1 h to 30 days of contamination in control and sterile distilled water groups. Decontamination with NaOCl was effective only when teeth were contaminated for 1 h. CHX was effective at both contamination times. NaOCl did not influence the bond strength (p>0.05). Higher values were observed with CHX (p<0.05). SEM showed formation of resin tags in all groups.Conclusion CHX showed better results for the irrigation of contaminated root canals both in reducing the bacterial contamination and in improving the glass-fiber post bonding.

Comparison of the effectiveness of four organic chemoattractants towards zoospores of Ulva pertusa and macrofouling.

Algal spores respond to many environmental variables, especially to chemical "cues". This chemotactic response can be utilized to attract spores, thereby colonization of a new substrata is possible to be influenced. In this attempt, four chemoattractant candidates were screened against spores of Ulva pertusa to reveal their efficiencies. Attachment and subsequent germination of Ulva spores were effectively influenced by these chemoattractant candidates. In particular 100 microg cm2 of D-glucose coating was found to enhance spore attachment by > 150%. Furthermore, field investigations carried out with test panels, clearly indicate the chemoattractive properties of test coatings. In recent years, various anthropogenic activities and natural hazards cause detrimental impacts on the benthic algae and other fishery resources. Artificial reefs have been laid on many coastal regions to increase or restore marine resources. Chemoattractant coatings can be applied on artificial surfaces to increase the colonization of benthic forms. It also can be used in the mariculture devices. Influence of chemoattractants on Ulva spores and fouling biomass estimated on test panels are discussed.

Effectiveness of Different Cleaning Agents against the Colonization of Candida spp and the in Vitro Detection of the Adherence of These Yeast Cells to Denture Acrylic Surfaces

PURPOSE: The aim of this study is to examine the effect Klorhex and Fittydent, which are used as cleaning agents on the adhesion of Candida on the surfaces of acrylic denture and palatal mucosa. In addition, ability of yeasts to adhere to acrylic strips was evaluated after applying these agents in vitro. MATERIALS and METHODS: Each group of 15 patients cleaned their dentures with either Klorhex or with Fittydent. The control group cleaned their dentures with water. RESULTS: It was found that 62.2% of the patients had colonies of Candida species on their palatal mucosa which was reduced to 51.1% after using these cleaning agents. The colonization rate with Candida spp on their dentures was reduces from 82.2% to 68.8% using these cleaning agents. The mean adhesion value of the Candida strains isolated from the acrylic strips were found to be 75cell/strip prior to applying the Klorhex and Fittydent and 37.5cell/strip and 15cell/strip after applying these agents, respectively. CONCLUSION: These results showed that Klorhex and Fittydent have a certain preventive effect on the colonization rate of Candida spp on the surface of these dentures, the palatal mucosa, as well as on the acrylic strips in vitro.

The role of biological adhesive and suture material on rabbit hepatic injury / O papel da cola biológica e do fio de sutura na lesão hepática em coelhos

PURPOSE: To evaluate the performance of fibrin adhesive and absorbable suture thread in the repairing of hepatic injures in rabbits. METHODS: New Zealand albino rabbits (n=16), males and females, from 5 to 6 months old, average weight of 2500 g, were distributed randomly in Group A (n-8) - biological adhesive and Group B (n=8) - suture thread. After anesthesia with acepromazine (1mg/Kg), ketamine (50mg/Kg) and fentanyl EV (0,5ml/Kg), it was performed a supra-umbilical median laparotomy, the median hepatic lobe was isolated and subjected to severe standardized incision. In the group B the incision edges were sutured with simple 4-0 catgut, in separated stitches. It was evaluated the total time of the procedure, the hemostasis time and hemorrhage volume. In the 21st post-operative day it was evaluated the presence of adherences and signs of infection in the abdominal cavity, and it was followed by the resection of the median hepatic lobe for the histological evaluation. RESULTS: The calculated mean and standard deviation showed that the procedure time, hemostasis time and bleeding amount were significantly smaller in the group of animals subjected to the use of fibrin adhesive. The surgical abdominal incision was significantly more extensive in the animals of the suture group (average of 6,8 cm) in relation to the adhesive group (average of 3,8), as well as the number of occurrences of abscesses. The adherence of the intestinal ansas to the sutured incision (group B) occurred in five cases and the major omentum adhesion occurred in all animals. In the group A (adhesive) it occurred adherences of the major omentum in three cases. The microscopy of the hepatic incision repaired with the use of fibrin showed that the inflammatory infection is less intense, not associated with the formulation of secretion in the abscesses, and therefore has a more favorable later cicatricial aspect than a conventional suture with surgical thread. CONCLUSION: In agreement with other...

OBJETIVO: Avaliar o desempenho do adesivo de fibrina e do fio de sutura absorvível no reparo de lesões hepáticas provocadas em coelhos. MÉTODOS: Coelhos (n=16),Nova Zelândia, albinos, machos e fêmeas, 5 a 6 meses de idade, peso médio de 2500 gramas, foram distribuídos aleatoriamente em Grupo A(n = 8) - adesivo biológico e Grupo B(n=8) - fio de sutura. Após anestesia com acepromazina (1mg/Kg), quetamina (50mg/Kg) e fentanylEV (0,5ml/Kg), realizou-se laparotomia mediana supra-umbilical, o lobo hepático médio foi isolado e submetido a uma lesão padronizada grave. No grupo A foi aplicado o adesivo de fibrina. No grupo B as bordas da lesão foram suturadas com categute 4-0 simples, em pontos separados. Avaliou-se o tempo total de procedimento, tempo de hemostasia e volume da hemorragia. No 21° dia de pós-operatório avaliou-se a presença de aderências e sinais de infecção na cavidade e procedeu-se a ressecção do lobo hepático médio para a avaliação histológica. RESULTADOS: A média e desvio-padrão calculados mostraram que o tempo de procedimento, tempo de hemostasia e quantidade de sangramento foram significantes menores no grupo de animais submetidos ao uso do adesivo de fibrina. A extensão da ferida operatória foi significativamente maior nos animais do grupo sutura (média de 6,8cm) em relação ao grupo adesivo (média de 3,8cm) assim como o número de vezes da ocorrência de abscessos. A aderência de alças intestinais à lesão suturada (grupo B) ocorreu em 5 casos e adesão do omento maior ocorreu em todos os animais. No grupo A (adesivo) foram observadas aderências do omento maior em três casos. A microscopia da lesão hepática reparada com o uso de fibrina mostrou que a reação inflamatória é menos intensa, não está associada à formação de secreção ou abscessos e com isso tem um aspecto cicatricial tardio mais favorável que uma sutura convencional com fio cirúrgico. CONCLUSÃO: Em concordância com outros trabalhos da literatura biomédica, o adesivo de fibrina é uma opção...

Resistência adesiva em esmalte de dentes clareados / Bond strength to enamel of bleached teeth

O objetivo deste estudo foi avaliar a resistência adesiva de uma resina composta ao esmalte de dentes tratados com agentes clareadores. No primeiro grupo, uma pasta de perborato e peridrol foi selada dentro da câmara coronária. No segundo grupo o peridrol foi aplicado sobre a superfície vestibular e dentro da câmara coronária, associado ao calor. No terceiro grupo os dentes foram expostos ao peróxido de carbamida a 10 por cento, aplicado sobre a superfície vestibular. O quarto grupo foi feito como controle. Os dentes foram armazenados por 10 dias em soluçäo salina a 37ºC. A resistência adesiva foi determinada por testes de cisalhamento. Os resultados indicaram um aumento de resistência adesiva para os dentes que sofreram clareamento

Comportamento de um sistema adesivo. Considerando variáveis de tempo de aplicaçäo do ácido e do "Primer": estudo "in vivo" / Behaviour of the adhesive system. Considered variable time application of acid and Primer: study \"in vivo\"

O objetivo deste trabalho foi avaliar "in vivo" a adesäo do sistema adesivo Scothbond M. P. Plus. Para este estudo foram utilizados os seguintes tempos de condicionamento ácido em dentina: 5, 15 e 45 segundos. E os seguintes tempos de aplicaçäo do "primer": 5, 60 e 120 segundos. Os corpos de prova foram obtidos através de cortes de dentes, no sentido mésio-distal, em aproximadamente 1mm de espessura. Cada corpo de prova por sua vez, sofreu uma reduçäo na uniäo dentina/resina em aproximadamente 1mm, resultando assim em uma área aproximada de 1mm², sendo esta a área analisada através do teste de traçäo. Foram utilizados 108 corpos de prova, obtidos através de cortes feitos em 36 pré-molares superiores e inferiores. Diante dos resultados obtidos concluiu-se que a variaçäo na combinaçäo do tempo de condicionamento ácido e tempo de aplicaçäo do "primer" melhoram o valor de adesäo, quando comparado com os tempos sugeridos pelo fabricante