Color Changes and Stainability of Complete Dentures Manufactured Using PMMA-TiO2 Nanocomposite and 3D Printing Technology-one year evaluation

Color stability through wear and time, one of the most important esthetic factor, influencing patient�s acceptance of an acrylic removable prosthesis, was investigated in vivo in a limited number of studies and solely on prefabricated denture teeth.The aims of the present paper were to assess the color changes occurred with the commercially available PMMA for 3D printing technique, improved by doping with titania nanoparticles, and to evaluate the color stability and stainability of the PMMA with 0.4%TiO2 denture teeth, on denture wearers, over a period of one year. Ten patients rehabilitated with removable complete dentures or implant retained overdentures manufactured using a new nanopolymer, PMMA doped with 0.4% by weight of TiO2 as denture base and artificial teeth material and Digital Light Projection (3D printing) technology, were evaluated in the present study. The color of each denture was assessed with a spectrophotometer, before and after use, in CIE L*a*b* system. The before measurement was made on the positive control - PMMA with nanoTiO2 (PC), while the after was measured the color of the tooth after one year complete denture use. Negative control - PMMA without nanoTiO2 (NC) was also compared to PC and the following parameters were registered: Value (L), Chroma (C), Hue (H), redness/greenness (a) and yellowness/blueness (b). A color difference (DE) between 1.63 and 5.24 was measured for all patients, while for the NC DE was triple (17.65). The highest DE value for all denture wearers with TiO2 nanofiler inclusions was below the maximum acceptability threshold, in accordance to the patient�s subjective evaluation, who were unable to identify the color change.