Periodontal measures improved in the treatment group compared with the control group at 6 months , with adjusted between-group differences of 0.28 mm ( 95 % CI , 0.18 to 0.37 ) for probing depth , 0.25 mm ( 95 % CI , 0.14 to 0.36 ) for clinical attachment loss , 13.1 % ( 95 % CI , 8.1 % to 18.1 % ) for bleeding on probing , and 0.27 ( 95 % CI , 0.17 to 0.37 ) for gingival index ( P < .001 for all ) .