Scientists may have found a solution to the sensitivity that normally follows silver amalgam cavity fillings. Though popular because of its strength and low cost, the high thermal conductivity of metal substances so close to the pulp tissue could cause pain. And it’s not just fillings – I’ve spoken with many people who can’t even get a normal porcelain bridge because of the metal often used to fuse the porcelain to the remaining teeth. Sometimes these metal substances do more damage than good for hypersensitive nerve endings.
Dental Filling Liners and Sensitivity
Dentists have tried several liners to protect the tooth from any extreme heat or cold transmitted through the metal, but many found those substances neither effective nor efficient. Researchers at D.A.V. Centenary Dental College at Yamuna Nagar in Haryana, India, found that a liner made of sodium fluoride (NaF) iontophoresis may help desensitize the root surfaces and prevent future cavities.
Traditional Teeth Fillings
Dental caries, commonly known as cavities, affects between 60-90% of teenagers and adults, according to the World Health Organization. Tooth decay occurs when oral bacteria interacts with sugars in the mouth to produce an acid reaction, which eats away at the surface of the teeth. Once a cavity develops, the dentist must drill out the rotting portion and fill the empty space with another substance. Possible substances include composite resins, porcelain, gold amalgam and silver amalgam. The silver or base metal amalgam has proven the sturdiest, most affordable option.
Dentists know that since metal has a high thermal conductivity and can cause pain when in contact with the root, they must place other substances between the tooth and the filling. Though they helped, bulky varnish and adhesive bonded liners did little to protect the tooth from pain caused by extreme cold or heat.
Alternative Filling Liner
Researchers explored the possibility of using NaF iontophoresis as a liner and discovered that it desensitizes the pulp and exposed roots to sudden temperature changes caused by silver amalgam fillings. It accomplishes this desensitization by sending fluoride ions into the exposed areas. The other options simply tried to block the areas from pain, whereas this liner actually works to dull the sensitive nerve endings. The fluoride also helps prevent further decay.
The study evaluated 30 patients ages 10-14 whose first molar had caries. Researchers used various liners on each patient between the tooth and the silver amalgam filling.
- They tested sensitivity first by poking the filled area with a sharp tool.
- For the thermal evaluation, they used both an air test and a water test. They blasted air on the tooth for one second, then trickled cold water onto the tooth from a syringe.
- Patients evaluated the pain on a four-level scale ranging from no discomfort to extreme pain even after the stimulus was removed.
Teeth treated with the NaF iontophoresis lining were found to be much less sensitive, both immediately and over time, than the molars treated with common adhesive or varnish liners.
Perhaps, with further development, researchers can expand this concept to other dental treatments as well.