Resin Bleaching Period
Initial After 7 days After 14 days
Adoro Saliva 43.00 (3.13) Aa 42.13 (4.08) Aa 39.24 (4.75) Aa
  Carbamide 43,21 (2.19) Aa 40.29 (1.92) Aa 39.71 (2.07) Aa
  7.5% Hydrogen 43.36 (2.81) Aa 39.75 (4.26) Aab 38.36 (4.32) Ab
  38% Hydrogen 44.39 (2.00) Aa 40.49 (3.11) Aab 36.41 (3.08) Ab
Resilab Saliva 42.08 (3.57) Aa 28.94 (3.50) Ab 28.45 (4.48) Ab
  Carbamide 42.84 (1.62) Aa 34.64 (3.79) Bb 28.92 (3.26) Ac
  7.5% Hydrogen 44.88 (2.41) Aa 35.14 (4.80) Bb 28.46 (1.95) Ac
  38% Hydrogen 42.91 (3.26) Aa 34.86 (3.97) Bb 31.39 (3.00) Ab
Cristobol Saliva 48.82 (1.97) Aa 46.07 (1.38) Aab 43.83 (1.41) Ab
  Carbamide 48.04 (0.84) Aa 42.54 (1.79) Ab 40.73 (1.70) Ab
  7.5% Hydrogen 49.37 (3.94) Aa 44.55 (2.11) Aab 41.67 (2.46) Ab
  38% Hydrogen 50.22 (2.98) Aa 43.41 (2.21) Ab 42.58 (1.50) Ab
Sinfony Saliva 21.15 (3.79) Aa 13.65 (3.98) Ab 12.35 (2.86) Ab
  Carbamide 20.41 (1.91) Aa 12.63 (2.90) Ab 12.47 (2.64) Ab
  7.5% Hydrogen 20.97 (1.71) Aa 12.83 (1.31) Ab 12.32 (0.99) Ab
  38% Hydrogen 20.67 (2.38) Aa 12.70 (1.65) Ab 11.34 (1.69) Ab
Epricord Saliva 38.96 (0.82) Aa 34.71 (1.60) Aab 33.95 (0.64) Ab
  Carbamide 39.66 (1.44) Aa 35.10 (2.58) Aa 34.81 (2.34) Aa
  7.5% Hydrogen 39.46 (0.85) Aa 34.42 (1.49) Ab 34.38 (1.13) Ab
  38% Hydrogen 39.96 (2.43) Aa 35.29 (2.45) Aab 34.66 (1.91) Ab
Means followed by the same uppercase letter in the column (comparison of each resin brand) and the same lowercase letter in the line does not differ to 5% level of significance (P<.05) in Tukey’s test.
Table 7: Mean results(Standard Deviation) of Knoop hardness of indirect composite resins for bleaching.