An investigation of the effect of powder reservoir volume on the consistency of alumina powder flow rates in dental air-abrasion devices

Objectives: To investigate the effect of powder reservoir fill volume on the emitted alumina powder flow rate of four dental air-abrasion units. The null hypothesis examined was that powder reservoir fill volume has no effect on a-alumina powder flow rate. Methods: The spent alumina powder from the four air-abrasion units tested (Abradent, Crystalmark, Clendale, CA, USA; Aquacut, Velopex, Horesham, UK; MicroPrep Associate Lares, Chico, CA, USA; Rondoflex 360, KaVo, Lake Zurich, IL, USA) was gathered in a collecting chamber over a 60 s running period. The difference in the weight pre- and post-collection was noted and flow rate calculated for different reservoir fill volumes (100%, 75%, 50% and 25%). Results: The powder flow rate of each machine was significantly affected by a change in powder reservoir volume (p <0.05). In all devices a partially empty reservoir caused a significant decrease in powder flow rate, compared to that at maximum fill volume. The maximum percentage difference seen using the Rondoflex was similar for 27 mu m and 50 mu m abrasive (70% and 69%, respectively), whereas, smaller differences were seen with the Abradent (59%), Aquacut 29 mu m and 53 mu m abrasive (62% and 30%) and MicroPrep (35%) machines. Conclusion: It was shown that the fill of the reservoir affects the powder flow rate of air-abrasion units, thus disproving the null hypothesis. In a clinical setting and in future research studies, the powder reservoir should be filled to a set level to achieve a constant and reproducible cutting performance of the tested units. (C) 2008 Elsevier Ltd. All rights reserved