Three-dimensionally printed and milled polyphenylene sulfone materials in dentistry: Tensile bond strength to veneering composite resin and surface properties after different pretreatments.

STATEMENT OF PROBLEM: Polyphenylene sulfone (PPSU) is a thermoplastic that can be processed using 3-dimensional printing. PPSU is new to dentistry, and scientific data on its properties are lacking.

PURPOSE: The purpose of this in vitro study was to test the surface properties and the tensile bond strength (TBS) between PPSU and a veneering composite resin in comparison with a polyetheretherketone (PEEK).

MATERIAL AND

METHODS

Gehr PPSU (PPSU-B1), Radel R-5000 NT (PPSU-B2), and Juvora Dental Disc (PEEK-CG) substrates were cut from bulk material, while FIL-A-GEHR PPSU (PPSU-3D) was 3-dimensionally printed (N=504, n=126/material). TBS to veneering composite resin (CeramageUp) was tested initially and after 5000 and 10 000 thermocycles, and fracture types were analyzed. Surface free energy (SFE) and surface roughness (Ra) were determined after pretreatment with aluminum oxide (Al2O3) of different grain sizes (50 and 110 μm) applied with different pressures (0.1, 0.2, 0.4 MPa), silicon dioxide (SiO2)-coated Al2O3 (0.28 MPa), sulfuric acid, or polished. Qualitative surface characterization was performed by using a scanning electron microscope (SEM). One-way ANOVA, the Kruskal-Wallis, Mann-Whitney U, and the Spearman correlation tests were computed (α=.05).

RESULTS

PPSU-3D and PEEK-CG presented higher TBS results than PPSU-B1 and PPSU-B2. Initial TBS values were higher than after 10 000 thermocycles. Adhesive fractures between substrate and veneering composite resin occurred most frequently. With a few exceptions, PEEK-CG presented higher SFE values than all other materials within a pretreatment group, while PPSU-3D and PEEK-CG showed consistently high Ra values. An increase in pressure and particle size increased SFE and Ra.

CONCLUSIONS

FFF-printed PPSU-3D showed similar TBS values with the veneering composite resin to the more established PEEK. Pretreatment methods devised for PEEK represent valid strategies for increasing both the SFE and Ra of the high-performance polymer PPSU.