Fig. 6

a Ultrasonic imaging at the implant in region 33 revealed buccal bone loss up to the 6th thread (asterisk marks the implant-abutment interface; circle marks the bone). b Ultrasonic imaging at the implant region 34 revealed buccal bone loss up to the 3rd implant thread (asterisk marks the implant-abutment interface; circle marks the bone). c Ultrasonic imaging at the implant region 35 revealed buccal bone loss up to the 2nd implant thread (asterisk marks the implant-abutment interface; circle marks the bone)