Significantly more complications occurred at both mandibular and maxillary grafted sites : 17 augmented patients were affected by complications versus 8 patients treated with short implants in the mandible ( P = 0.0079 ; difference in proportion = -0.45 ; 95 % CI -0.67 to -0.15 ) , and 5 sinus-lift patients versus none treated with maxillary short implants ( P = 0.047 ; difference in proportion = -0.25 ; 95 % CI -0.44 to -0.06 ) .