Effects of Filler-Surface on Hardness and Wear of 3D-Printed Composites

Objectives: Objective
Evaluate efficacy of novel method that applies silanized-glass filler incorporated Three-Dimensional Printed (3DP)-resin to sample surface during post-printing process(PPP) to improve surface hardness and wear resistance properties.
Methods: Methods
A novel method was used to fabricate 3DP-resin material (C&B MFH, NextDent, Soesterberg, Netherlands) with PPP applying a thin layer of unpolymerized resin mixed with fumed Silica particles (average size 0.3-0.04mm) surface-treated with g-methacryloxypropyl trimethoxysilane (Sigma-Aldrich, St. Louis, MO), then UV-cured in a SprintRay post-cure chamber(SprintRay, Los Angeles, CA). The Control Group is 3DP-resin with normal PPP and the Experimental Group is surface treated during PPP. Samples were evaluated for surface roughness change with a profilometer, PCE-RT1200 (PCE America, Jupiter, FL) after abrasion under tooth-brushing simulator. Sample thickness and weight before and after brushing simulation were also measured. Vickers surface hardness was measured. Sample size of n=8 selected, based on the recommended optimal values of pilot trial for two-tailed main trial designed with 80% upper confidence level and standardized differences of 0.9 with 80% power.
Results: Results
All results are presented in the TABLE. Two tailed t-test compared the means of the two experimental groups. Surface hardness was significantly increased with novel PPP method we developed.
Conclusions: Conclusion
In this study we applied a novel method that surface treats 3DP-compatiable resin with silane-modified silica particles(70%w/w). With this modification, we report increased hardness of 3DP-resin when compared to the unmodified resin. As a result, 3DP-resin can increase its surface hardness by including an additional step during the PPP by applying a layer of 3DP-resin added with silanized glass fillers. Our report adds to the possibility of 3DP-resin as an indirect restorative material for inlays and onlays applied chairside for clinical applications, via digital intraoral scanning, computer design and chairside fabrication via additive manufacturing in a form of 3DP technology.