Analysis of Physical and Mechanical Properties of Universal Composites under Different Types of Polishing before and after Acid Challenge

Table 6

Mean values (standard deviation) of Knoop microhardness of the composite resin’s specimens according to the brands at different times.

Groups	After polishing	After challenges
	T1	T2
Estelite	40.9 (3.68) Aa	34.3 (4.34) Ab
Palfique	42.5 (5.53) Aa	37.5 (4.32) Bb
Z350	69.3 (7.82) Ba	58.9 (6.07) Cb

Note: Means followed by the same capital letter in the column and lowercase in the row do not differ at 5% significance level () by Tukey’s test.