A finalidade deste estudo foi verificar, por meio da análise da microinfiltração marginal, se o estado de hidratação da dentina ácido-condicionada influencia a qualidade do selamento marginal em restaurações de resina composta. Foram empregados 60 terceiros molares humanos, divididos em seis grupos, nos quais foram realizados preparos cavitários, tipo slot vertical, nas faces mesial e distal, com término gengiva1 em cemento. Após a lavagem das cavidades condicionadas com ácido, as mesiais foram secas com jato de ar por 15 segundos e as distais mantidas Úmidas, removendo-se apenas o excesso de água com papel absorvente. Foram aplicados os seguintes sistemas adesivos: Perma Quik, Scotchbond Multipurpose Plus, One-Step, Prime & Bond 2.1, Single Bond e Syntac Single Component, sendo então procedida a restauração com resina composta. As amostras foram submetidas a termociclagem (500 ciclos a 5°C +/- 5ºC e 50°C +/- 5ºC) e imersas em fluoresceína sódica a 2% por 15 horas. A avaliação foi realizada em microscópio de epifluorescência por dois examinadores, atribuindo-se escores de 0 a 5 conforme o grau de infiltração marginal. Os resultados foram submetidos a análise estatística empregando-se os testes de Wilcoxon, Kruskal-Wallis e Conover

The aim of this study was to evaluate the influence of moist and dry dentin on the sealing ability of six adhesive systems on marginal sealing of composite restoration. Sixty extracted human third molars received slot preparations below the CEJ at mesial and distal surfaces. The teeth were divided in six groups according to the dentin adhesive used: I) Perma Quik; II) Scotchbond Multipurpose Plus; IU) One-Step; IV) Prime & Bond 2.1; V) Single Bond and VI) Syntac Single Component. After acid conditioner was rinsed off, the mesial cavities were air-dried for 15 seconds, end in the distal cavities the surfaces were blotted with small piece of absorvent paper, so that they remained visibly moist prior to bonding. All adhesive systems were applied to the preparation surfaces according to the manufacturer's directions. The composite resin Prisma TPH was used to restore all teeth according to manufacturer's instructions. All specimens were thermocycled for 500 full cycles at 5ºC and 55°C (dwell time of 30 seconds), stored in a 2% sodium fluorescein dye for 15 h ours, and then sectioned mesio-distally. The extent of microleakage was determined for gengival walls following a criteria ranging from 0 to 5. The Wilcoxon, Kruskal-Wallis and Conover statistic tests were applied to the obtained data. Conclusion: the moist dentin was more effective for marginal sealing with four adhesive systems. The Single Bond and One-Step were the adhesive systems most infuenced by the moisture content of the dentin.