There are more than 2.5 billion variations in charting one person's mouth. From the shape of the tooth, to the shape of the root canal, it all can be used to solve a crime.

"The first thing that we do is we do a visual examination, all over the skull; make note of any injuries that may be involved in the death. Those could be injuries to the skull, to the facial area; missing teeth, broken jaw, makes notes of those. But, after that it is basically a normal dentist appointment," said Tulsa dentist, Dr. Keith Montgomery.

Dr. Keith Montgomery has been working for the Tulsa County Medical Examiner for more than 20 years. Forensic dentists have to go through a training program. Montgomery attended the armed forces institute of pathology.

In order to identify the remains of a victim, narrowing down the possibilities is essential.
"To start off you have got to have an idea who the person is. Either when they're found, they have some identification on them. If not we can determine the age, the race the sex, and then we go to the missing persons and start narrowing it down," said Dr. Montgomery.

Dr. Montgomery says the most time consuming part of the entire process is usually finding dental records of the missing persons that could fit the remains found. Missing teeth, a filling, cosmetic dentistry, and jaw bone structure are key in the investigation. The last thing investigators want to do is give a grieving family false hope.

Working to solve the mystery is much different than the job of the everyday dentist and it can be a hard job to do.

"Sometimes there are tough cases, obviously when you have kids involved or horrific crimes involved obviously those are tougher cases to deal with. You go and do what you're trained to do, and then you go to the next one. If you didn't you shouldn't be doing that type of work," said Dr. Montgomery.

By Margaret Stokes, NewsOn6.com anchor/reporter and Kyle Dierking, Video Journalist. Find more of their stories in our Web Exclusives section.