Evaluation of the influence of decontamination methods after contamination with blood in different moments during the dentin adhesive process

A contamina????o durante a realiza????o de procedimentos restauradores ?? citada na literatura como um evento muito freq??ente, apesar disso, poucos s??o os trabalhos que avaliam a influ??ncia desta contamina????o na ades??o e poss??veis m??todos de descontamina????o a serem realizados frente a sua ocorr??ncia. Assim, este trabalho teve como objetivo avaliar a influ??ncia dos m??todos de descontamina????o no selamento marginal e na resist??ncia ?? extrus??o de um sistema adesivo dentin??rio. Foram utilizados 135 incisivos bovinos, que tiveram a face vestibular desgastada expondo-se dentina, onde foram confeccionadas cavidades circulares padronizadas. Estas foram distribu??das em tr??s grupos: A) controle, sem contamina????o (n = 15); B) contamina????o previamente ?? fotoativa????o do adesivo (Adper Single Bond 2 - 3M ESPE) (n = 60) e C) contamina????o ap??s a fotoativa????o (n = 60). Ap??s a contamina????o as cavidades foram divididas (n = 15) de acordo com o m??todo utilizado: 1) papel absorvente; 2) ??gua; 3) condicionamento com ??cido fosf??rico ou 4) hipoclorito de s??dio a 10%. As cavidades foram restauradas com o comp??sito (Filtek Z250 - 3M ESPE), aplicando-se um ??nico incremento. Ap??s 24h as restaura????es foram polidas e os esp??cimes submetidos ?? ciclagem t??rmica (500 ciclos/5??C a 55??C/30s). O selamento marginal foi avaliado utilizando-se o corante azul de metileno a 2% (pH = 7,0) seguido da digitaliza????o das restaura????es. Os esp??cimes foram desgastados pela face lingual expondo a restaura????o, e submetidos ao ensaio de extrus??o (push out) em uma m??quina de ensaios mec??nicos. Para a an??lise estat??stica foram utilizados ANOVA segundo dois crit??rios (momento x m??todo) e Teste de Tukey. Na avalia????o do selamento marginal houve signific??ncia estat??stica para o fator momento (p<0,001) e tamb??m para intera????o momento X m??todo (p=0,008). O n??vel m??dio de margens coradas encontradas ap??s a fotoativa????o foi estatisticamente superior ao encontrado previamente a fotoativa????o (p<0,001). Dentro do Grupo B o m??todo condicionamento demonstrou uma m??dia de margens coradas estatisticamente superior ao grupo ??gua (p<0,003), e os grupos papel e hipoclorito demonstraram valores intermedi??rios. Para as compara????es entre m??todos dentro do Grupo C n??o foram detectadas diferen??as significativas. Em rela????o ?? resist??ncia ?? extrus??o, apenas o fator momento demonstrou ser estatisticamente significante (p<0,001), sendo os valores do Grupo B estatisticamente superiores (p<0,05) aos do Grupo C (5,32??3,03 e 3,4??1,92 MPa respectivamente). Todos os m??todos demonstraram valores de resist??ncia similares ao controle. Maiores valores de resist??ncia foram relacionados a menores valores de margens coradas. Concluiu-se que a contamina????o com sangue ap??s a fotoativa????o do sistema adesivo teve um efeito adverso na capacidade de selamento de restaura????es de comp??sito e os diferentes m??todos de descontamina????o geralmente produziram resultados similaresContamination while restoration procedures are carried out is mentioned in literature as a very frequent event, besides that, there are only a few papers which value this contamination influence in adhesion and possible decontamination methods to be carried out under such an occurrence. So, the aim of this study was to evaluate the influence of decontamination protocols upon dye leakage and push-out bond strength of a dentin adhesive system. It was used a hundred thirty five bovine incisors, which had their labial surface ground to obtain a flat dentine surface where standardized cylindrical cavities were made and they were divided in three groups: A) control without contamination (n = 15); B) contamination prior to the adhesive light activation (Adper Single Bond 2 3M ESPE) (n = 60) and C) contamination after the light activation (n = 60). After the contamination the cavities were divided (n = 15) according to the protocol used: 1) absorbent paper; 2) water; 3) conditioning with phosphoric acid or 4) sodium hypochlorite at 10%. The cavities were restored with the composite (Filtek Z250 3M ESPE), applied to only one increment. After 24 hours the restorations were polished and the specimens were subjected to thermal cycling (500 cycles/5o C a 55oC/30s). The exposure of the stained margins was done through the use of 2% methylene blue dye (pH = 7.0) and digital measurement of the restorations. The specimens cavity floor was ground, exposing the restoration, and they were submitted to the extrusion test (push out) in a universal testing machine. To statistics analysis it was used ANOVA according to two criteria (moment and protocol) and Tukey s test. In the marginal sealing evaluation there was significant statistics in the moment factor (p<0.001) and also in the interaction moment x protocol (p<0.008). The percentage average of stained margins found after light activation was statistically higher than the ones found prior to the light activation (p<0.001). In group B the conditioning protocol showed a percentage average of stained margins statistically higher than the water group (p<0.003), and the paper and hypochlorite groups demonstrated intermediate values. Comparing to group C protocols, it was not detected significant differences. Relating to the extrusion resistance, only the moment factor was statistically significant (p<0.001), while group B values were statistically higher (p