Table 1.

Distribution of surface area and number of decayed surfaces in three groups

		N	Mean	Minimum	Maximum
Surface area (mm2)	I	20	80.95	62	102
	II	25	56.10	43	78
	III	21	38.29	28	55
	Total	66	56.78	36	133
No. of decayed surfaces	I	20	2.75	1	4
	II	25	3.20	2	4
	III	21	3.57	2	4
	Total	66	3.18	1	4