For years, forensic dentists told courts with confidence that every person’s bite mark is unique, and that a bite on skin could be matched to a suspect almost without doubt. This belief put people behind bars. Later, some of those people were found to be innocent.

Bite mark analysis sits at an uncomfortable intersection in forensic science — a technique that sounds scientifically solid on paper but has increasingly struggled to hold up when real science was applied.

The Theory Behind Bite Mark Analysis

At first sight, the logic appears reasonable since each person’s teeth differ slightly in size, spacing, wear, and alignment, and so a bite should, in theory, leave a unique pattern. Forensic odontologists compare the bite mark—typically one found on the victim’s skin in cases of violent crime—with the dental impressions of the suspect, seeking a match in terms of tooth width, rotation, and spacing. Starting in the 1970s, this method was employed in criminal trials, and for many years it was given the same degree of confidence in court as fingerprint or DNA evidence.

Where the Science Falls Apart

1. Skin Is a Terrible Canvas

Unlike a fingerprint left in ink or a shoe print in mud, skin is elastic, curved, and constantly changing. A bite mark can distort within minutes due to swelling, healing, or even just the position of the body. The same bite, photographed at different times, can look meaningfully different — making precise comparison far shakier than it sounds.

2. No Proven Uniqueness

The entire method rests on the assumption that human dentition is unique enough to be matched reliably, and that this uniqueness transfers accurately onto skin. Multiple scientific reviews — including a landmark 2009 National Academy of Sciences report — found no solid research validating either assumption. Two different odontologists analyzing the same bite mark have, in real cases, reached completely different conclusions about who it came from.

3. Wrongful Convictions

Bite mark evidence has since been linked to a number of wrongful convictions, several of which were overturned by DNA evidence years — sometimes decades — later. These cases became a turning point, prompting legal and scientific bodies to publicly question whether bite mark matching should be admissible in court at all.

What’s Considered More Reliable Today

Forensic odontology hasn’t been abandoned — parts of it remain genuinely valuable:

• Dental identification of the remains (that is, matching dental records with a body) is still regarded as being scientifically valid since it involves comparing existing records rather than making subjective pattern matches.
• Estimating a person’s age from their teeth, particularly in the case of juveniles, is still a firmly established forensic method.
• The comparison of bite marks to identify the person who produced a particular bite is the one aspect that has come under the most criticism, and in recent years several U.S. states and courts have placed restrictions on it or excluded it.

Where the Field Is Headed

Rather than throwing out bite mark evidence entirely, many forensic scientists are pushing for it to be used only as exclusionary evidence — ruling suspects out rather than confidently ruling someone in. Some labs are also exploring 3D scanning and digital overlay techniques to reduce the subjectivity that made earlier bite mark testimony so unreliable.

The Takeaway

Bite marks make for a compelling story — a wound that supposedly tells you exactly who caused it. But forensic science isn’t supposed to run on compelling stories; it’s supposed to run on evidence that holds up to scrutiny. Bite mark analysis is a reminder that “sounds scientific” and “is scientifically validated” aren’t always the same thing — and that courtrooms have had to relearn that lesson the hard way.