Abstract:

Objective　It has been demonstrated thatwhen a high-speed handpiece stops rotating, negative pressure will form. Thus, contaminating fluid inwhichthere are many kinds of bacteria and viruses fromthe external environmentwill retract into vari- ous compartments of the handpiece and the dental unit. The purpose of the study is to compare the preventing effect of antisuction designed handpiece and conventional handpiece on viral contamination at different rotating times.Methods　Twenty handpieces with or without antisuction device (10 of each) were used in the study. Each handpiecewas submerged into 10-6μg/μlHBVpar- ticle solution rotating 5 and 10 times respectively (every time rotating for 10 seconds). Samples were obtained from the water line and chip air line of the handpieces and examined by RT-PCR.Results　At the same rotating times, there was statistical signifi- cance of the viral concentration between the two kinds of handpieces (P<0.05). However, therewas no statistical significance of the viral concentration between different rotating times in each group (P>0.05).Conclusion　Contamination taking place in both water and air lines of dental handpiecewas not enhanced by increasingthe number of rotatingtimes of the handpiece. The an- tisuction devices installed into the water line and chip air line were demonstrated to prevent viral contamination effectively.

Key words: handpiece, virus, retraction, cross contamination