Assessing the Impact of Titanium Dioxide Nanotube Incorporation on the Coefficient of Thermal Expansion and Degree of Conversion of 3D-Printed Denture Base Resin

Hot or cold food and drink consumption causes temperature fluctuations in the oral environment. A dental prosthesis fitted in such environments might thermally expand or contract in response to heat fluctuations. A significant difference in thermal expansion characteristics between various denture parts (denture bases, artificial teeth, etc.) might result in the development of interfacial stress, which leads to a shortened denture shelf-life. This study aims to assess the effects of incorporation of titanium dioxide (TiO2) nanotubes (NTs) into 3D-printed denture base resin on the coefficient of thermal expansion (CTE) and the degree of conversion (DC%). TiO2NTs with a dimeter of 30- 70nm and length of 2-4μm were incorporated into the 3D-denture base liquid resin at 0.0wt% (control), 1.0 and 2.0wt% groups. Total 30 digitally printed samples for coefficient of thermal expansion with (n=10) samples were tested for each subgroup and were analyzed by a Thermomechanical analyzer. Attenuated Total Reflectance -Fourier transform infrared spectroscopy was performed to analyze degree of conversion utilizing total 26 samples with (n=6) for each of the photo-polymerized 3D-printed groups samples (control, 1.0wt.% and 2.0wt.% TiO2NT composite) and uncured 3D-printable liquid resin samples as baseline. The results showed that increasing TiO2NT concentration enhance the coefficient of thermal expansion and no significant differences for degree of conversion. The clinically significant is that: The improvement in the coefficient of thermal expansion of 3D-printed resin owing to the addition of TiO2NTs could diminish marginal weakening at the border between different denture parts, resulting in extended denture shelf-life.