Biaxial flexural strength (BFS) of BTHM and ETHM copolymers and their ACP and OX50/ZrO2 composites in dry state and after 1 mo, 3 mo and 6 mo immersion in buffered saline solutions at 23 °C. Shown are the mean values ± standard deviation (SD) for a minimum of seven specimens in each experimental group. SDs (in MPa) were: ≤ 38 for BTHM copolymer, ≤ 12 for BTHM ACP composites, ≤ 34 for BTHM OX50/ZrO2 glass composites, ≤ 23 for ETHM copolymer, ≤ 18 for ETHM ACP composites and ≤ 30 for ETHM OX50/ZrO2 glass composites.