Lares Research supports the use of 27 micron powder. The results of our clinical evaluations have supported the use of 27 micron to be the clinicians' choice. One reason is that 27 micron powder is more efficient at lower pressures where patient sensitivity is less likely. If a patient begins to report sensitivity during preparation, a slight reduction in air pressure will usually offer immediate relief. Also, avoid long exposures to the abrasive stream by cutting with short abrasive bursts.
Many clinicians are able to prepare cavities that are near pulp exposures without sensitivity.
This is a function of both the experience of the clinician and the pain threshold of the patient. Clinicians have reported a dramatic decrease in their need for anesthesia in deeper preparations with low air pressure and experience. All cutting should be done with the tip in motion and with short, intermittent activation of the abrasive stream. Any place where the tip is held stationary while the abrasive stream is active will exhibit excessive depth of cut. If a large area of soft decay is encountered, it is best to remove it with a spoon excavator or a slowly rotating bur in a lowspeed handpiece.