Table 2 Median irradiance loss (lowest value; maximum value) of indirect restorative materials at varying thicknesses (mm)

GRA

52.1 (51.3;55.3) ^{a B}

71.2 (70.1;73.9) ^{ab AB}

79 (69.7;79.5) ^{ab AB}

79.9 (79.1;80.6) ^{b AB}

VSC

69.2 (69;70.3) ^{a A}

75.4 (74.7;76.4) ^{ab A}

83.8 (83.1;84.3) ^{bc A}

89.4 (89.3;90.1) ^{c A}

VBM

57.8 (57;60.4) ^{a AB}

63.3 (62.8;65.2) ^{ab B}

68.4 (67.7;69.2) ^{bc B}

71.8 (69.4;72.8) ^{c B}

p

0.002

0.002

< 0.002

< 0.002