Groups A and C exhibited a significantly lower plaque index scores ( parameter-estimate -LSB- @ % confidence interval -RSB- = -@ -LSB- -@ to -@ -RSB- for group A , and -@ -LSB- -@ to -@ -RSB- for group C ) and gingival index scores ( -@ -LSB- -@ to -@ -RSB- , and -@ -LSB- -@ to -@ -RSB- ) , respectively , compared with group D ( P < @ for all ) , whereas no significant difference was found between groups B and D , or between groups A and C ( P > @ ) .