The effect of ozone on tooth colour in vitro

Objectives: It has been suggested that when ozone breaks down to release a free oxygen radical this may be able to whiten teeth. The aim of this study is to measure any change in tooth colour value following the application of ozone. The null hypothesis was that ozone will not have an effect on tooth colour value. Methods: This study investigated 30 freshly extracted human teeth, all size matched. Tooth colour was analysed for all teeth using the L*a*b colour system determined by setting the tooth up in a custom-made jig and then using the Easyshade (Panadentltd.co.uk) colorimeter. Teeth were then randomly allocated to a treatment group for 40s or 80s ozone application or a control group (identical procedure including vacuum application without ozone). Ozone was applied using the Healozone device (Kavo.co.uk), which requires the application of a vacuum, into a sealed chamber modified to enclose the tooth. The teeth were kept moist between stages. Results: The L value (indicating colour value) increased by 1.04+0.57 (n=10) after a 40s application of ozone and 0.85+0.60 (n=10) after 80s application. These L values returned to baseline levels by 7 days. The control teeth showed an increase in L value by 1.60+1.92 (n=10). These preliminary results show an increase in tooth value following ozone application and following vacuum without ozone but this is less than a single application of 35% carbamide peroxide gel for 40min (Patel, Louca, Millar. JDentRes 2004 82 Spec Iss, abst 155). Further experiments are underway to investigate the effect of longer exposure times. Conclusions: Ozone does appear to lighten teeth but this may be due to dehydration.