This study concerns to the investigation of the polymerization shrinkage in dental experimental composites filled with silanized silica Aerosil® OX-50 and clay nanoparticulated Montmorilonita (MMT) Cloisite® 30B, in glycidyl methacrylate resin. The characterization of the experimental composites was established with the following analyses: Thermo-Mechanical Analysis (TMA) at isotherm temperature, Differential Scanning Calorimetry Analysis (DSC) under nitrogen atmosphere, X-Ray diffraction (DRX), and Micro Hardness analysis. Through the TMA analysis was observed that the polymerization shrinkage varies according to the filler type and concentration in the experimental composite. The polymerization shrinkage ranged from 0.98% to 0.22% in the experimental composites added with Cloisite® 30B and ranged from 2.73% to 1.01% in the experimental composites containing silanized silica. Due to the intercalation of the clay nanoparticle in relation to the polymer matrix, the experimental nanocomposites with Cloisite® 30B showed better performance compared to the composites with silanized silica. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40010.