Binghamton Press & Sun-Bulletin
Greater Binghamton, NY
http://www.pressconnects.com/
November 30, 2005
Question: Why exactly does it hurt when aluminum comes into contact with fillings in teeth?
Answer: The kind of tooth pain you're talking about comes from stimulation of the nerve that resides in the middle of the tooth. The nerve normally is encased in bone-like dentin, and the dentin in turn is protected by a layer of enamel. In the case of tooth decay, the enamel is worn away by acids produced by bacteria sticking to your teeth (plaque). The nerve is then accessible to the outside environment through pores in the unprotected dentin, and stimulation of the nerve through these pores by, for example, just blowing air on the dentin causes pain.
Tooth decay is commonly treated by drilling out the decayed part of the enamel and dentin, and then filling the hole with a mixture of mercury and silver, or with gold. These metals effectively seal off the nerve from the outside environment, preventing pain.
Aluminum and the metal filling form parts of a battery. Batteries that use metal work by transferring electrons (current) to or from metals. Without a wire connecting the plus and minus sides, the battery just has potential to transfer electrons. However, when the aluminum foil comes into contact with the metal filling in the tooth, the battery is shorted out, and current flows through the filling and the dentin, and to the nerve, giving the sensation of pain.
Ask a Scientist appears Wednesdays. Questions are answered by faculty at Binghamton University. Teachers in the greater Binghamton area who wish to participate in the program are asked to write to Ask A Scientist, c/o Binghamton University, Office of Communications and Marketing, PO Box 6000, Binghamton, N.Y. 13902-6000 or e-mail. Check out the Ask a Scientist Web site at askascientist.bingham ton.edu.
ASK A SCIENTIST
Today's question was answered by James A. Dix.
Title: Associate professor of chemistry, Binghamton University
Department: Chemistry
Ph.D. school: University of California, Los Angeles
Educational background: NIH postdoctoral fellow, Harvard Medical School; research fellow, Cardiovascular Research Institute, University of California, San Francisco; visiting scientist, Theoretical Biology and Biophysics, Los Alamos National Laboratory. Family: Married; two children, one child in college, one in work force Interests/hobbies: Old English sports cars and motorcycles, model trains, computer programming, socializing Web page address:http://chemistry.binghamton.edu/DIX/dix.html
Today's question was asked by student Chris Barnes.
School: Sidney High School
Grade: 12
Teacher: David Pysnik
Hobbies: Hunting, fishing, ATV riding
Career interest: Teacher