When is it time to replace my Ultrasonic insert?

Effectiveness of deposit removal and patient comfort are two of the most important aspects of periodontal debridement.  Effective deposit removal is measured not only by complete ‘removal’ of calculus and biofilm but also by the speed at which this is accomplished.  

For ultrasonic debridement, the number one reason for ineffective deposit removal and patient discomfort is a worn ultrasonic insert.  That said, how does a clinician know it is time to replace an insert?

The general rule of thumb for insert replacement is…

Once an insert loses 50% of its original active tip it needs to be replaced.  

Active tip is based on frequency.  Therefore, it is important for a clinician to know the frequency of the equipment they are using.  The latest Cavitron equipment runs at a frequency of 30K and has an active tip that is 4mm in length.  Cavitron wear indicator cards (see figure 1) are available and these tools accurately assess insert wear and efficiency.  

Tip Wear Reduces EfficiencyFigure 2 shows how tip wear reduces efficiency.  Notice how stroke size is reduced as active tip is lost.  

  • 25% lost insert tip (which equals 1mm) produces 25% lost efficiency.  With 1mm of tip wear, clinically one may start to notice a small change in effectiveness of the insert and patients may or may report and change in sensation.   However, time to think of reordering.
  • Wear Indicator50% lost insert tip (which equals 2mm) produces 50% lost efficiency.  With 2mm of tip wear, clinically calculus does not come off as effectively. To compensate for the lack of effectiveness, clinicians adjust by increasing lateral pressure.  An increase in lateral pressure further compromises the removal of the deposit and makes the procedure uncomfortable (or very uncomfortable) for the patient.  In addition, application of lateral pressure is accompanied by an increase in pinch grip and this added pressure between the thumb and the index finger contracts muscles in the hand/wrist, increasing risk for musculoskeletal injury.   

Want to test this theory?  Simply ultrasonic a colleague’s teeth using an insert with 50% (or more) wear versus a new insert and ask them how it feels.