Table 1.

Intragroup comparison of mean surface microhardness changes of enamel before and after exposure to beverage

Groups	Mean ± SD		Paired t value	p value
	Baseline (KHN)	Posttreatment (KHN)
Group I beverage without CaGP	350.9 ± 25.6	221.8 ± 19.1	17.111	0.000 HS
Group II beverage + 2 mM CaGP	357.7 ± 44.8	224.4 ± 16.1	11.271	0.000 HS
Group III beverage + 5 mM CaGP	340.06 ± 44.4	318.5 ± 50.9	1.52	0.163
Group IV beverage + 10 mM CaGP	345.8 ± 26.7	346.7 ± 42.3	−0.074	0.943

Paired t test

HS, highly significant; KHN, Knoop hardness number; SD, standard deviation; CaGP, calcium glycerophosphate