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When worn down by the daily process of chewing, or mastication, teeth have the capacity to crack and break. Narayana Sundaram, a master's student in UMBC’s mechanical engineering program, is examining this common form of teeth failure, known as the ‘cracked tooth syndrome.’

In the process of restoring a tooth, a dentist removes decayed material and fills in the cavity in your tooth. “Unfortunately, a restored tooth is prone to fracture, leaving a person with one less tooth to chew upon” explains Sundaram. “Clinical studies have shown that about 90 percent of fractured teeth have been previously restored.” Analyses have indicated that a repaired tooth can fail after anywhere from five to 25 years, depending on the depth of the cavity preparation and the oral habits of the patient. In other words, almost everyone who gets a filling will have trouble with that tooth, sooner or later.

Sundaram is focusing his research on the middle layer of the tooth, known as dentin; in addition to the enamel (the outer layer of the tooth), dentin is an area that dentists often need to fill in to repair a cavity. Unlike enamel, which is brittle and hard, dentin is resilient; this means that the daily wear and tear due to mastication has the capacity over time to lengthen a crack already present in dentin. Once the crack reaches a critical size, the tooth fractures.

“There is almost no description of fatigue crack growth and related properties in the literature for dentin,” says Sundaram. ”Therefore, the fatigue properties of dentin remain unknown.” As a result, Sundaram has spent a lot of time looking at dentin and fatigue cracks in bovine (cow) teeth, which are similar in structure to human teeth. Much of this is due to the fact that it’s easier to obtain specimens for bovines; bovine teeth are also larger in size and easier to analyze. Now, however, attention has shifted to human specimens. “Dentists are working with us around Baltimore, supplying human teeth,” says Sundaram. While there is not yet a viable solution for more efficient ways to prevent cracking, Sundaram suspects that the tubules, small tubes in the dentin that run perpendicular to a tooth crack, will be pivotal in finding ways to reduce crack growth.

The role that the age of the patient plays in fatigue crack growth is the next area of inquiry to be undertaken in the research lab of Dr. Dwayne D. Arola, Sundaram’s advisor. His personal involvement with the project impressed Sundaram, and was a big factor in Sundaram’s decision to attend UMBC. “He plays a huge role,” says Sundaram of Arola. “He was the person that initiated this study. He’s helped me with equipment, models and ideas. Whenever I get stuck, I go back to him he’s been great.”

The challenge of exploring the unknown excites Sundaram, who received first place in Physical Sciences at the 2003 UMB/UMBC Graduate Research Conference. ”Many people still do not understand this area,” he says. “There is no base procedure here.” Sundaram’s enthusiasm is catching. He remembers one humorous moment where a person showed willingness to fund his entire project. “A lady who came to a poster-judging I had attended had a lot of fillings. After my presentation, she came up to me and jokingly said, ‘I would personally fund you if you would keep working on this project!’”