Millions of Americans have silver tooth fillings, but a local dentist said those filling could cause serious medical problems.

The silver fillings -- used by dentists for more than 200 years -- are made with 50 percent mercury.

Dr. Jeff Hartman, DMD, said the fillings have "created a major rift in the dental association. Two-hundred years ago ... there were practitioners who believed that (the fillings) were going to potentially harm patients."

Hartman has been removing mercury fillings at his Huntingdon County dental practice for more than two decades. He said that when his first patient asked for the procedure, he was skeptical. But, soon after, his patient's overall health improved.

"In a small community you get to watch people get better and that was the only change in her life that happened at that period of time," he said.

He said he then started doing more research on silver fillings.

"They were invented with the idea that it was a substance that could fix the tooth that killed bacteria," he said. "Mercury is very toxic to bacteria ... that's sort of why it works."

Hartman said mercury is toxic to every enzyme system in body. If an individual has a weakness in one of those systems, he said those are typically the areas he starts to see symptoms in.

The Environmental Protection Agency has warned about the dangers of mercury exposure for years. It is known that mercury can cause neurological problems and dangers to a developing fetus.

Late last year, the Food and Drug Administration rejected conclusions that mercury tooth fillings are safe. The FDA said more than 2,000 consumer complaints have flooded in, reporting adverse health effects from individuals with silver mercury fillings.

At an FDA hearing, more than 50 people testified about debilitating symptoms and recoveries from diseases including multiple sclerosis, Parkinson's disease, chronic fatigue syndrome and depression.

Since 1979, the use of silver amalgam fillings has dropped by 40 percent. Hartman said he has eliminated the use of silver fillings at his practice altogether and instead uses diamond crown fillings.

"There is really no reason to be putting toxic materials in anyone's mouth," he said.