There were no statistically significant differences in bone level changes up to 1 year between 6 mm and at least 10 mm-long implants in both jaws ( mandibles n = 18 , mean difference -0.02 mm , 95 % CI -0.16 to 0.12 , P = 0.7384 ; maxillae n = 20 , mean difference -0.07 mm , 95 % CI -0.18 to 0.05 , P = 0.2547 ) .