Influence of silver coated zeolite fillers on the chemical and mechanical properties of 3D-printed polyphenylene sulfone restorations.

OBJECTIVES

To investigate the chemical and mechanical properties of polyphenylene sulfone (PPSU) depending on its composition and manufacturing.

METHODS

Unfilled-PPSU1 and with antimicrobial silver coated zeolites filled-PPSU2 specimens were made of granulate-GR, filament-FI, or printed-3D. Scanning microscopy and X-ray spectroscopy were performed. Martens hardness-HM, elastic indentation modulus-E and flexural strength-FS were determined initially and after aging. Shear bond strength-SBS to veneering and luting composite after conditioning with 7 adhesive systems were examined after aging. Silver leaching was tested after 1-, 3-, 7-, 14-, 21-, 28- and 42 days. Analyses of variance, Kolmogorov-Smirnov, Kruskal-Wallis, Mann-Whitney U, unpaired t-tests and Weibull modulus were computed (p < 0.05).

RESULTS

Zeolites were homogeneously distributed. PPSU1-GR and PPSU1-FI showed the highest HM/E, followed by PPSU2-GR, PPSU1-3D and PPSU2-3D. PPSU2-FI presented the lowest HM/E, displaying micro pits. Aging showed reduced HM/E in PPSU1 and no impact on PPSU2, while FS increased (PPSU1) or decreased (PPSU2). PPSU2-3D presented lower FS than PPSU1-3D. High SBS to the luting (7.0-16.2 MPa) and veneering composite (11.8-22.2 MPa), except for adhesive system PR, were observed. PPSU2-3D showed the highest silver release (9.6%), with all compositions dispensing silver over 42 days.

CONCLUSIONS

For the examined period of 6 weeks, antimicrobial silver ions were released from filled PPSU. The high SBS between PPSU and veneering/luting composite confirmed the feasibility of esthetically veneering and luting filled PPSU. To achieve mechanical properties like unfilled PPSU, the processing parameters of filled PPSU require refinement.

CLINICAL SIGNIFICANCE

This investigation provides proof of principle that PPSU can be successfully doped with silver-coated zeolites. The combination of 3D-printing with an antimicrobial thermoplastic constitutes a great opportunity in the field of prosthetic dentistry. Potential applications include clasps for removable dental prostheses, provisional or permanent fixed dental prostheses and implant abutments.