2.3. In Vitro Cytotoxicity Test

The MTT assay was performed to evaluate the cytotoxicity according to ISO 10993-5 [11]. In brief, the specimens with 10 ± 0.1 mm in diameter and 1 ± 0.01 mm in height were prepared. The sample was sterilized under UV light for 30 min and immersed in serum-free media (3.0 cm²/mL) according to ISO 10993-12 [12]. After a day, the supernatant was decanted into another well and diluted with serum-free media. Mouse fibroblast cell line, L929, was seeded at 1 × 10⁴/cells in a 96-well plate, in 100 μL of cell culture medium RPMI 1640 with 10% of FBS. After a day, the medium was changed to extractions from each type of material (1:1) or dilutions of extractions with serum-free media (1:2). After another day, the extractions were removed and 50 μL of MTT solution (1 mg/mL) were added. After two hours, the solutions were changed to 100 μL of DMSO to dissolve purple formazan. After that, the microplates were read using a microplate reader (Epoch microplate spectrophotometer, Synergy-BIOTEK, Winooski, VT, USA). The tests were repeated three times and all results were calculated as relative values by dividing the negative control group.