Calcified and Connective Oral Tissue Focus Group -
Research Highlight 2

"Fighting Tooth Decay with Laser" -
a project by Assoc Professor Stephen Hsu

The fight against tooth decay may soon be won with a new treatment method utilising laser power. This treatment method forms a patina of protection against acids, produced by micro-organisms on the tooth. Laboratory studies show a 98 per cent protection against tooth decay - the world's best record to date.

Laser-induced birefringent changes indicating the blocking of micro-diffusion system in human enamel.

Tooth enamel is made up of about 97 per cent crystal which is inorganic in nature, and a one per cent organic matrix. The organic matrix functions as the basic scaffold for the crystals to build on. Tiny gaps, existing between the crystals and the matrix, provide a diffusion pathway vulnerable to the attack of bacteria and acids. When this happens, tooth decay results. In the past three decades, research on preventive laser treatment has developed along the lines of melting the crystals at a very high temperature of 1000 degrees Celsius or higher to form a shield over the gaps. With the collaborative help of a multidisciplinary team, Dr. Hsu inverted the paradigm and used a low-energy laser to melt the organic matrix instead. The resulting melted organic matrix provides a stronger armour of defense, preventing decay by an additional 25 per cent. Furthermore, by using a low-energy laser, the nerve of the tooth is likely to be protected from harm. In addition, the purifying effect of the laser energy on the crystals at the lower temperature range provides optimal lattice strength for the tooth. The original method of laser treatment, on the other hand, runs the risk of inflicting irreversible damage on the nerves in the tooth and crystals when the heat is too high. If clinical trials for this new treatment method prove successful, dental practitioners will have another weapon in their battle for healthy teeth.

Dr. Hsu has called the method "organic blocking" and his research has been published in the Journal of Dental Research, and won him the "Foundation Research Award" conferred by the American Academy Pediatric Dentistry in 2001, in addition to the "Research in Prevention Award" conferred by the International Association for Dental Research in 1998.

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