Introduction: Finishing and polishing materials did not develop as the composites improved in these last years. The nanometric load particles were firstly and only incorporated in the polishing pastes formulation in this in vitro and in situ study. Objective: This study evaluated the biofilm retention of two different composite resins -Vit-l-escence™ (microhybrid) and Filtek™ Z350 XT (Nanofilled) after finishing and polishing technique, quantification and in situ comparison of the polishing pastes effectiveness with micrometric loads (Enamelize™ and Diamond Polish Paste™) and Nanofilled load -Lummina-E (Alumina and Diamond). Materials and Methods: Ten volunteers were selected for the in situ biofilm evaluation, a palatal device made of acrylic resin was confectioned, and each intra-oral device had fixed six specimens from each experimental group. After exposition to 20% sacarosis, the biofilm from each specimen was extracted in NaOH 1.0 M and quantified by absorbance spectrophotometer. The data were submitted to analysis of variance, followed for multiple comparisons of averages for the ad hoc de Dunn test, both at 1% significance level. Results: Vit-l-escence™ resin showed lower biofilm retention than Filtek Z350™ XT in all the tested groups. The lowest biofilm retention was after aluminum oxide paste (Lummina-E -Alumina) polishing. Conclusion:The Vit-l-escence™ (microhybrid) composite resin exhibited lower biofilm retention than Filtek™ Z350 XT (nanofilled) resin among all the tested groups. The lowest in situ biofilm retention occurred at the surfaces treated with Lummina -E Alumina (folder-based aluminum oxide) nanometric prototype.