Which type of scaling system is best? 
Medline and the Cochrane Central register of Controlled Trials were searched for relevant studies.  Randomised controlled trials and controlled clinical trials conducted in vitro or in vivo on human teeth, which used plaque, bleeding, gingivitis or pocket depth, clinical attachment level, microbiological findings, patient perception and treatment time as outcome measures, were included.  Case reports, letters and narrative or historical reviews were excluded and only English-language papers were considered.  The studies included differed in design and outcome so a qualitative summary was presented.  Fifteen studies met the inclusion criteria.  The Vector (Dürr Dental, Bietigheim-Bissingen, Germany) ultrasonic scaler (VUS) provided clinical and microbiological periodontal healing results comparable to scaling and root planing and a conventional ultrasonic system in moderately deep pockets.  The VUS may be used as a gentle root debridement device for supportive periodontal therapy, as an alternative to other conventional ultrasonic systems.  The operator should consider, however, the extra time needed for instrumentation.