Tooth whitening by a direct current cold plasma micro-jet

Summary form only given. Eating habits, smoking, drugs and chemicals can cause undesirable staining of teeth. Tooth whitening has become a popular dental practice to remove stains from the tooth surface for aesthetic or therapeutic purposes. Traditional in-office tooth whitening involves applying dental gel (active compound: H
₂
O
₂
) on patients teeth for several 15-20 minutes intervals. However, studies have shown that prolonged use of clinical teeth-whitening gel (with concentration of H
₂
O
₂
up to 30-40%) can be harmful. In this work, we present tooth-whitening results of extracted teeth treated by a direct-current, cold, atmospheric-pressure air plasma micro-jet (PMJ). Dental gels (Beyond Technology Corporation, USA) with different concentrations (6%, 15%, 25%, 35%) of H
₂
O
₂
are applied to teeth during the treatments. A considerable improvement of the whitening effect was observed when dental gel with lower (such as: 6% and 15%) concentration of H
₂
O
₂
was applied. The improved whitening is attributed to the effective production of reactive oxygen species (ROS) such as atomic oxygen (O), hydroxyl radical (OH) and singlet molecular oxygen (
¹
O
₂
). The surface temperature of the tooth during the plasma treatment was monitored and found to remain below 40°C. Modification of tooth surface was detected through a scanning electron microscope (SEM), X-ray microanalysis (SEM/EDS) and microhardness test. This novel tooth-whitening approach, especially the improved whitening effect with lower concentration of H
₂
O
₂
in dental gel, might revolutionize clinical tooth whitening process.