Laser technique removes tooth decay

Dental caries — an infectious disease that damages tooth structure — is the most common chronic childhood disease in the US. If left untreated, the malady can be painful and can lead to tooth loss. Removal of caries generally involves using rotary carbide burs, which are small metal cutting heads of various shapes that are used with a manual instrument for even removal of decay. However, bur treatment does not always result in complete caries removal and can lead to overexcavation as well as to painful and uncomfortable side effects.

As reported in the April issue of the European Journal of Oral Sciences, Dr. Henrik Dommisch from University Hospital Bonn in Germany and his colleagues evaluated the application of a fluorescence-controlled Er:YAG laser as compared with conventional rotary carbide bur treatment for caries removal.

They treated 102 teeth with carious lesions in 26 adult patients. Each lesion was divided into two areas that were randomly assigned to either laser or bur treatment. An Er:YAG laser device from KaVo of Biberach, Germany, provided a pulsed infrared beam with a 2.94-μm wavelength on a spot size of 0.63 mm. A fluorescence feedback system in the device, which included an InGaP diode laser, enabled the researchers to detect infected carious dentine. While experimenting with the diagnostic laser, they selected threshold levels of 7, 8, 9 and 10 relative units.

After the laser and bur treatment, they evaluated the teeth for the presence of caries-related bacteria and found that the fluorescence-controlled laser treatment at threshold levels of 7 and 8 removed caries at a statistically similar level to that of bur treatment. However, nearly 90 percent of the lesions treated at fluorescence threshold levels of 9 or 10 were not caries-free and required additional excavation with rotary burs.

More than 75 percent of the patients said they experienced no pain when treated with the laser, but only 20 percent said they felt no pain with the bur treatment.

The investigators conclude that the laser treatment provides an effective and less painful approach to caries removal when used at threshold levels of 7 and 8.