Alternating among hand and ultrasonic instruments allows the operator to use different muscle groups
while performing periodontal debridement. When using an ultrasonic unit such as SWERV³, the
following principles should be followed for proper body positioning^2,9:

• One’s head should be straight or slightly flexed, and the shoulders relaxed
• The elbows are flexed at 90 degrees or less
• Wrists are positioned neutrally
• The lower lumbar curve should be maintained throughout the procedure