Some 4th year students were concerned about the amount of power they should use when using an ultrasonic scaler for root debriding and the damage that could be done if too much power is used.
My understanding is that the more power we use with the ultrasonic the more risk of damage there is to the tooth surface. But rather than make an unfounded claim I thought I'd have a quick look on TRIP for some evidence while I'm sitting at a garage having my tyres changed...that's what I do when I have a day of annual leave :(
My search was: dentine AND (removal OR damage OR scratch*) AND (ultrasonic OR cavitron)
This brought up several papers but the one that seems most relevant was this one:
Ultrasonic scaler oscillations and tooth-surface defects.
This was a lab study that showed that increasing the power from low to high on two types of ultrasonic scaler increased the depth of defect created in the dentine by up to 4 times. There was also an increase in damage done when doubling the force applied, but this was not as significant as the power setting change.
I grant that the defects created even with high power are just 0.1mm deep after limited instrumentation. But if we were to reinstrument the same area many times in a patient's lifetime this could become quite significant, risking damage to the pulp. (I wonder also if the defect wouldn't be another plaque trap too, which would kind of defeat the objective of root surface debridement).
This is just one study but it seems to be an indication to keep the power as low as possible to do the job required. Let me know if you read other research on this.