Polycarbonates are polymers of bisphenol A (BPA), a well-known endocrine disruptor. This study evaluated the release of BPA from polycarbonate crowns that were (1) milled from Temp Premium Flexible (ZPF, Zirkonzahn, Italy) or Tizian Blank Polycarbonate (TBP, Schütz Dental, Germany), or (2) 3D-printed (Makrolon 2805, Covestro, Germany). Commercial prefabricated polycarbonate crowns (3M, USA) and milled poly(methyl methacrylate) (PMMA) crowns (Temp Basic, Zirkonzahn, Italy) were included for comparison. The crowns were stored at 37 °C in artificial saliva (AS) or methanol, which represented the worst-case scenario of BPA release. Extracts were collected after 1 day, 1 week, 1 month and 3 months. BPA concentrations were measured using liquid chromatography-tandem mass spectrometry. The amounts of released BPA were expressed in micrograms per gram of material (μg/g). After 1 day, the highest amounts of BPA were measured from milled polycarbonates, TBP (methanol: 32.2 ± 3.8 μg/g, AS: 7.1 ± 0.9 μg/g) and ZPF (methanol 22.8 ± 7.7 μg/g, AS: 0.3 ± 0.03 μg/g), followed by 3D-printed crowns (methanol: 11.1 ± 2.3 μg/g, AS: 0.1 ± 0.1 μg/g) and prefabricated crowns (methanol: 8.0 ± 1.6 μg/g, AS: 0.07 ± 0.02 μg/g). Between 1 week and 3 months, the average daily release of BPA in methanol and AS decreased below 2 μg/g and 0.6 μg/g, respectively. No BPA was released from PMMA in AS, and the cumulative amount released in methanol was 0.2 ± 0.06 μg/g. In conclusion, polycarbonates could be a relevant source of BPA, but the current tolerable daily intake of BPA (4 μg/kg body weight) should not be exceeded.

Department of Prosthetic Dentistry University Hospital LMU Munich Goethestraße 70 80336 Munich Germany

Department of Prosthodontics Center for Dentistry and Oral Medicine Goethe University Frankfurt Theodor Stern Kai 7 60596 Frankfurt Germany

Institute of Dental Medicine 1st Faculty of Medicine Charles University General University Hospital Karlovo Namesti 32 121 11 Prague Czech Republic

Institute of Endocrinology Narodni 139 8 116 94 Prague Czech Republic

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