No statistically significant difference ( P = 0.62 ) was observed comparing the frequency of CAL gain 4 mm between EMD + DBBM ( 60 % ) and CM + DBBM ( 50 % ) or comparing the frequency of residual PD 6 mm between EMD + DBBM ( 5 % ) and CM + DBBM ( 15 % ) ( P = 0.21 ) .