A LASER wand could replace the dentist鈥檚 drill if clinical trials beginning
next year are successful. The key is photodynamic therapy (PDT), in which light
activates a killer molecule that wipes out bacteria in decaying teeth.
In tests on extracted teeth, Mike Wilson and his team at the Eastman Dental
Institute in London have shown that PDT sterilises the infected tooth tissue.
Once teeth in people鈥檚 mouths are clear of infection, their bone tissue should
be able to regenerate itself.
The team also hopes PDT could help combat other infections, particularly the
hospital 鈥渟uperbugs鈥� that are resistant to antibiotics. The team has already
tested PDT against MRSA, a virulent superbug. 鈥淲e wiped out over 99.9 per cent
of the colony in samples where human tissue was present,鈥� Wilson told the BA
meeting.
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To treat cavities, dentists drill the parts of the tooth infected with
decay-causing bacteria, leaving only healthy tissue. 鈥淢ost dentists are
overcautious and drill away a large part of the tooth,鈥� says Wilson.
PDT uses a photosensitiser molecule which binds only to the bacteria. When
the photosensitiser is bathed in laser light, it releases oxygen radicals that
kill the bacteria by punching holes in them.
Wilson says he has disinfected extracted teeth using a photosensitiser called
toluidine blue. He will begin clinical trials in people with cavities next
year.
The researchers don鈥檛 think bacteria will become resistant to PDT. 鈥淪o far,
we haven鈥檛 found any one site the photosensitiser is binding to,鈥� explains Mark
Wainwright of the University of Central Lancashire, who is also working on PDT.
鈥淚t just seems to adhere generally around the cell walls.鈥� He says the bacteria
would have to change several aspects of their structure to become resistant.