The Effect of Gastric Acid on the Surface Properties of Different Universal Composites: A SEM Study

Table 3

Mean and standard deviations of surface hardness parameter for all tested composite resins.

Resin composites ()	Initial deviation	7^th day deviation	14^th day deviation
Omnichroma	^A	^a,B	^g,C	0.002
Charisma Diamond One	^D	^b,E	^e,F	0.002
Vittra Unique	^G	^b,c,H	^e,h,I	0.002
Neo Spectra	^J	^b,d,K	^f,L	0.002
A’CHORD	^M	^b,N	^e,O	0.002
Nova Compo C	^P	^b,R	^e,h,S	0.006

Capital letters refer to statistical groupings for each evaluated time (line), and small letters indicate significant difference in hardness parameter (column) ().