http://www.revmaterialeplastice.ro MATERIALE PLASTICE ♦55♦No. 4 ♦2018 616 Structural Investigations on Poly(methyl methacrylate) Various Composites Used for Stereolithographyc Complete Dentures EUGENIA EFTIMIE TOTU 1 , CORINA MARILENA CRISTACHE 2 *, SELIM ISILDAK 3 , OZLEM TAVUKCUOGLU 3 , AIDA PANTAZI 4 , MARIUS ENACHESCU 4 , ROXANA BUGA 5 , MIHAI BURLIBASA 2 , TIBERIU TOTU 5 1 University Politehnica of Bucharest, Faculty of Applied Chemistry and Material Science, 1-5 Polizu Str, 11061 Bucharest, Romania. 2 University of Medicine and Pharmacy Carol Davila, Faculty of Midwifery and Medical Assisting (FMAM), Department of Dental Techniques, 8, Eroilor Sanitari Blvd, 050474, Bucharest, Romania 3 Department of Bioengineering, Faculty of Chemical and Metallurgical Engineering,Yildiz Technical University, 34210 Esenler- Istanbul, Turkey 4 University Politehnica of Bucharest, Center for Surface Science and Nanotechnology (CSSNT), 313 Splaiul Independentei, 060042, Bucharest, Romania 5 University Politehnica of Bucharest,Faculty of Electronics and Telecommunications,313 Spl. Independentei, 060042, Bucharest, Romania The present paper is focused on analyzing if appropriate adhesion between the polymeric matrix and titania filler nanoparticles is obtained for the PMMA-TiO 2 photo-curable dental material, suitable for application in RP - stereolithography (SLA) for complete denture manufacturing. It was found that different amounts, between 0.2% and 2.5 % (w/w%), of added titanium oxide nanoparticles slightly modify the structural behavior of the PMMA polymeric matrix. The material characterization was carried out using FT-IR and microscopy techniques. Keywords: PMMA - TiO 2 functionalized nanocomposite, structural analysis, stereolithography, complete denture The advancements in computer-aided design and computer aided manufacturing (CAD/CAM) encouraged its applications in fixed and removable prosthodontics, leading to the development of new technologies and new materials with improved biomechanical characteristics and high biocompatibility. To date, subtractive technology (milling from gingiva-colored pre-polymerized acrylic blank) for denture base and prefabricated teeth are mostly used, in clinical environment, to manufacture CAD/CAM dentures. Despite of the important advantages of this technique, such as reduced number of appointments, rapid fabrication, improved fit and electronic archiving of prosthetic design, computer engineered complete dentures have some important drawbacks, mainly regarding the expensive materials and increased laboratory costs [1,2]. Additive manufacturing or rapid prototyping (RP) and the use of improved polymers has been foreseen as a viable and less costly solution for complete denture manufacturing. Furthermore, if a monolithic denture/ overdenture [3,4] is envisaged, the functionalization of the polymeric teeth during the design may also be performed [5]. Poly (methyl methacrylate) (PMMA), the material of choice for removable dentures, has been lately investigated and there are studies highlighting the effect of adding nanofillers such as titanium dioxide (TiO 2 ) to improve their specific properties [6]. PMMA-nano TiO 2 composite have shown better thermal behavior [7] in connection with a lower water sorption and solubility [8]. From the mechanical point of view, such composites are characterized by an improved hardness, fracture resistance and/or flexural strength [9]. However, some studies have shown lower flexural strength when titania nanoparticles were added into a poly (methyl methacrylate) matrix [10]. Such noted behavior could be the result of a poor homogeneity of the final material. The present study was focused on obtaining an appropriate adhesion between the polymeric matrix and titania filler nanoparticles for the PMMA-TiO 2 photo- polymerizing material for dental use, important for enhancing the nanocomposite’s characteristics. The structural properties of the PMMA-nanocomposites suitable for application in RP - stereolithography (SLA) dentistry have been characterized by FT-IR analysis and microscopy investigations. Experimental part Reagents and apparatus The reagents used in this work are similar to those presented in our previously published paper [7]. The polymer matrix, denoted as PMMA-D, consisting in a mixture of poly(methyl metharcrylate)(PMMA) -methyl methacylate (MMA) and reinforcing additives solution (from EnvisionTEC GmbH, Gladbeck, Germany) has been used throughout experiments, as provided. The nanofiller added to the polymeric matrix was the titanium oxide (anatase type) - from Aldrich. The obtained material has been used for complete dentures manufacturing employing STL technology. The applied workflow, described elsewhere [11, 12], was run on Envison TEC equipment. In order to avoid the inhomogeneity and local agglomeration of the nanofiller within the PMMA matrix, the titania nanoparticles have been functionalized with methacrylic acid (Aldrich) according to the procedure described in detail in [7]. After functionalization, the nanofiller was carefully mixed with the PMMA-D matrix. The necessary amounts of the two components of the nanocomposite were precisely weighed with an analytical balance in order to obtain a concentration between 0.2 and 2.5 (w/w) for TiO 2 nanoparticles in polymer. * email: corinacristache@gmail.com All authors have equally contributed to the manuscript and they should be regarded as main authors