Table 2. Results of 2-way analysis of variance for the surface roughness measurements, ceramic types and the interaction terms after different APF exposure times (* p < 0.05).

Effect	DF	SS	MS	F	P
Type of ceramic	5	3.0020	0.6004	16.56	0.0000*
Exposure time	2	3.6995	1.8497	91.86	0.0000*
Ceramic versus exposure time	10	0.3418	0.0341	1.70	0.0904