The improvement of ultrasonic instrument has expanded its debriding field from supragingival area to subgingival exposed root surface and pocket wall during periodontal essential therapy.

• 摘要龈下超声器械的发展使超声治疗器械在牙周基础治疗中的重心由龈上逐渐转向牙周袋内壁和深层裸露根面等龈下组织结构。