Laser helps determine dental health

[Anonymous]

Dentists can now size up the mineral content of tooth enamel non-invasively with the help of laser-generated ultrasound.

This is the first time anyone has employed such a tool to find the elasticity of our teeth, besides assessing dental health and predict tooth decay and cavities.

Enamel goes through a cycle of mineral loss and restoration, through a lifetime, in which healthy teeth maintain a high mineral content.

If the balance between mineral loss and gain is lost, however, teeth can develop areas of softened enamel — known as carious lesions — which are precursors to cavities and permanently damaged teeth.

“The ultimate goal is to come up with a quick, efficient, cost-effective, and non-destructive way to evaluate the mineralisation of human dental enamel,” says study co-author David Hsiao-Chuan Wang, graduate student at the University of Sydney (U-S).
These findings were described in the latest issue of Optics Express, Optical Society’s (OSA) open-access journal.

        

[Drsumitra]

 To determine the effects of fluoride and pH on enamel de- and remineralization, a study by Dr. Frank Lippert, et al used quantitative light-induced fluorescence to in­vestigate enamel lesions under conditions designed to resemble plaque fluid. Pre­formed enam­el lesions were exposed to partially-saturated lactic acid solutions with varying fluoride concentrations (0.0 ppm, 0.1 ppm, 0.5 ppm, 1.5 ppm, and 4.0 ppm) and pH levels (4.9, 5.2, and 5.5). The average fluorescence loss was monitored for 11 days. Then, the enam­el lesions were demineralized in a partially-saturated acetic acid solution for 2 periods of 24 hours each. The lesions in the plaque fluid of a 4.0-ppm fluoride concentration and a 5.5-pH level were found to show the most remineralization after 11 days and the most demineralization after exposure to acetic acid. Increasing the fluoride concentration resulted in more remineralization regardless of the pH level, and increasing the pH level resulted in more remineralization. The lesions exposed to no fluoride showed no remineralization regardless of the pH level. The study found that fluoride had a stronger effect on remineralization and net mineral change than pH.

        

[Drsumitra]

 A study by Dr. Car­men Gonzales, et al investigated the effect of systemic fluoride intake from birth to 12 weeks on orthodontically induced root resorption and tooth movement in rat mo­lars. Fifty male rats were randomly di­vided into the following 5 groups: a neg­ative control group that re­ceived no so­dium fluoride and had no tooth movement; a positive control group that re­ceived no sodium fluoride but had tooth movement; and 3 experiment­al groups that received 45-ppm sodium fluoride from birth to 2, 4, and 12 weeks, respectively. At week 10, a 50-g nickel-titanium coil spring was ap­plied to the maxillary left first molar for 2 weeks. At week 12, movement of the maxillary first mo­lars was measured in relation to the maxillary second molar on digitized cephalometric radiographs. Mesial and distal roots were examined by using scanning electron and 3-dimensional laser microscopes. The study found that fluoride reduced the depth, volume, and roughness of the resorption craters in the experimental groups. Yet, the area was similar to that in the positive control group. The longer fluoride was administered via drinking water, the smaller the amount of tooth movement ob­served. It concluded that fluoride in drinking water from birth reduced the severity of orthodontically induced root resorption, but the amount of tooth movement was also decreased.

        

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