Forensic Dentistry

We've all heard it - local news reports identifying a body from dental records. But how does this work? Well, that's our job! See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

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• 0:04Josh Clark?

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• 1:03Speaker 03

  Welcome to Stuff You Should Know, a production of iHeart Radio.

• 1:13Josh Clark?

  Hey, and welcome to the podcast. I'm Josh, and there's Chuck and Jerry's not here, but she's here in spirit. We're all flashing our pearly whites because we're in a lineup, and this is stuff you should know.

• 1:24Speaker 02

  That's right. Or in my case, the front four are my pearly off-whites. Because when they made me my new set of four teeth to go up front to replace my four teeth, they were too white and they looked weird.

• 1:37Josh Clark?

  Oh, really?

• 1:38Speaker 02

  And they said, we can send them back and have them stain just a bit more. And I went, yeah, we're gonna have to do that.

• 1:44Josh Clark?

  Like Matt Dillon in There's Something About Mary?

• 1:48Speaker 02

  They weren't quite chicklet white, but they were enough to where they looked a little different than the others, and the others are just gonna, you know, as teeth do, continue to stain a bit. So it's like, yeah, why don't we go ahead and knock it down a notch?

• 2:02Josh Clark?

  You should have just smoked a bunch of cigarettes, done it yourself, saved some money.

• 2:07Speaker 02

  I don't think these implants will... That's the problem, is they don't stain while the others are.

• 2:12Josh Clark?

  Oh, okay. Well, then, yeah, you definitely need to hand those off for staining in the lab.

• 2:17Speaker 02

  Yeah, I'm like, why have I just smoked eighty cigarettes? Uh, so today, another, and I thought we were done with forensics, but who knew? That lurking out there was the topic of forensic dentistry, which we will learn very quickly, as in right now, kind of can be divided up into two things, which is identification of deceased people or peoples from dental records, like when you hear like, you know, they perished in the fire, but they were able to identify the body. And the much more controversial bite mark analysis that had been widely used in court and is now generally thought of by most dentists

• 3:02Speaker 02

  and people in this line of work as junk science.

• 3:05Josh Clark?

  Yeah, it's, I mean, just from researching this, it's like, what kind of judge is still allowing this in as evidence? It's crazy.

• 3:12Speaker 02

  Yeah.

• 3:13Josh Clark?

  Yeah, so I guess I just revealed my take on forensic dentistry or bite mark analysis specifically, because the other version you said identifying deceased people is

• 3:25Speaker 02

  Not as controversial.

• 3:26Josh Clark?

  No, it's not, it's pretty, pretty much set. Most, I didn't read anybody who was challenging it or its legitimacy, and apparently it's been really useful over the years because the teeth are the strongest part of the body. They can survive fire, they can survive exposure to chemicals, they could just get rid of the rest of the body. They can survive explosions up to, I think, 2,000 degrees Fahrenheit. They can take heat up to that. As anyone who's made it far enough from Breaking Bad knows that eventually, if it gets hot enough, they'll pop like popcorn. But most of the time, if a dead person who's unidentifiable comes into a medical examiner's office, they have not been exposed to that level of heat.

• 4:09Speaker 02

  Yeah, and even if the teeth themselves are struggling to hang in there, tooth pulp or dental tissue on the inside of that tooth is very resistant to environmental attacks like incineration, immersion, like you can be underwater for

• 4:25Speaker 02

  I was about to say a million years, but that's probably not true. But immersion, trauma, decomposition, so extracting DNA from the inside of a tooth is a pretty viable thing. But before 1974, all you really had going was identifying victims of a disaster usually, a natural disaster or a human caused disaster. They did not really get into crime scene stuff because in 1975 is when that first became permissible in court where a murder victim had a bite on her nose and three forensic dentists came along and said, hey, it's pretty clear this bite came from this person.

• 5:09Speaker 02

  It should be maybe the exception to the rule, but we should allow it in court this time.

• 5:14Josh Clark?

  Yes, and that was a very fateful decision because as that case made its way through appeals in a final appellate court upheld it, that also simultaneously not only convicted the killer, it also, it said, this is legitimate. Bite mark analysis is admissible in court. It set a precedent and that, that exception that those three forensic dentists in their defense, you know, went to bat for, for use in this particular case.

• 5:43Speaker 02

  Right.

• 5:44Josh Clark?

  Became the rule. And there was no longer like, hey, this is not actually that great of an idea. It was, hey, we've got this new way of prosecuting scumbags. Let's use it to the max. And there was a really famous case within just a couple of years of it becoming widely used in American courts that's still celebrated today as one of the great successes of bite mark analysis because it's not like every single case is worse than the last.

• 6:12Speaker 02

  Yeah.

• 6:12Josh Clark?

  But there's enough bad cases and enough people who've been wrongly convicted and later exonerated based on bite mark evidence that it should not, it's not, it should not be allowed. You just go figure out who did it some other way. Stop using bite mark analysis.

• 6:28Speaker 02

  Yeah, dozens of people, according to the Innocence Project. And we should point out, from 1975 until just recently, like 2016 is when they finally made a firm decision, which, you know, we'll hold on to that one, but that's really when things changed. But I think the case that you were talking about is Ted Bundy. In 1978, notorious serial killer Ted Bundy would sort of wind up his serial killing career by wandering into the Chi Omega sorority house at Florida State University and bludgeoning and killing four students, sorority sisters there, including one victim where he bit

• 7:12Speaker 02

  her and left very clear bite marks. And those bite marks were instrumental in Ted Bundy's conviction.

• 7:19Josh Clark?

  Yeah, the two Chi Omega women who died, who did not manage to live, were Lisa Levy and Margaret Bowman. But he did some pretty terrible damage to the other two, I guess. But that bite mark, apparently Ted Bundy had extremely crooked front teeth, so much so, and the bite mark was clear enough that they used that bite mark analysis in part to convict him for those murders. He apparently admitted to killing 30 women, possibly killed as many as 100. And so, one of the cases he was prosecuted for were the Chi Omega murders.

• 7:58Speaker 02

  Yeah, that's right. So, that's a good setup. We should just mention, sort of as far as the identification, the non-controversial part, adults usually have 32 teeth, four incisors, four canines, eight premolars, 12 molars, and four wisdom, depending on if you still have those. And when you go to the dentist, they, you know, we've been to the dentist, and they do a lot of notating. They notate your teeth, variations in your teeth, changes in your teeth, if you chip a tooth, any dental work you've gotten, like crowns, or fillings, or bridges, or in my case, four implants, periodontal disease, receding gums. There are x-rays, and there are just the tooth charts.

• 8:41Speaker 02

  And these are the dental records that we speak of when they say, you know, a body was identified via dental records. It's because of all this work that you get over the years at the dentist. I guess if you, well, this doesn't have so much to do with bite mark analysis. I guess it could, but the records, it seemed like, are mainly about identification.

• 9:02Josh Clark?

  Yeah. And also by law, I think every state requires dentists to keep dental charts on their patients. And then they also have to retain them for a set number of years, depending on which state demands what. So they do come in handy. Just the charts alone will, like, there's not going to be x-rays with them necessarily. There's not going to be any photographs. Just from the charts and the coding systems that they've worked out to codify teeth can conceivably give you enough information that you could use it in some form of forensic dentistry. That's how accurate the charts are meant to be.

• 9:42Speaker 02

  Yeah, for sure. So, you know, we mentioned all the ways teeth can hang in there and stay, you know, a part of your skull when other parts of your body have deteriorated. Teeth can shrink. They can become fragile. But if you handle them gently and with care, you can preserve them in lacquer. And what will happen if you need to identify a corpse usually is a dentist will go to the morgue. They will surgically expose the jaw and examine things. That's if you have, like, you know, a pretty recent dead body that hasn't decomposed too much. If all you've got is a handful of teeth, that still may be enough due to those x-rays and charts.

• 10:27Speaker 02

  But if it's mass casualties, a dentist is gonna, and these are forensic dentists, by the way. It's a specialty.

• 10:33Josh Clark?

  Right.

• 10:34Speaker 02

  They get a list of possible victims. And then, you know, you start comparing different records of the different people to try and sort out who is who.

• 10:42Josh Clark?

  Yeah. Yeah, it takes a special kind of dentist to do this kind of work because... By the time the cadaver, the corpse has made it to the forensic dentist, everybody else upstream has said like, no, they don't have fingerprints. Their face is unrecognizable. It just keeps going on and on and on until finally, your last chance of identifying the person is forensic dentistry. And though often, I mean, like if it's a mass casualty, you know, you know who was on the plane. Apparently that's when it comes in handy a lot for plane crashes. You know, all the passengers on the plane, you go get their dental records. You hand them over to the forensic dentist and say, good luck. Can you match any of these teeth with these charts?

• 11:25Josh Clark?

  And they're, they're, I mean, they're a huge part of a forensic team in like mass casualty events. They're, they're really important because again, they're like the last hope of some families getting closure. Being able to like give their loved one a funeral or something like that. Like that's the role that they're, they're playing. They're not doing this because they like just playing with dead people's teeth or anything like that. Like they are helping other humans with their work by identifying disaster victims, not extending that to bite mark analysis.

• 11:57Speaker 02

  Yeah, yeah, for sure. Um, there's a lot of things you can sort of glean from looking at a person's teeth about that person. It's not the most exact science, but we know generally how fast teeth grow about four micrometers per day. So you can estimate someone's age based on their teeth.

• 12:16Josh Clark?

  Well, not only that, you can also like when your teeth develop as a human, it follows a set pattern. So you can go and look at somebody's development, especially if they're under age, I think 20 something or 35. And say, well, they have, they've developed this tooth, but they haven't developed this tooth. So they're probably 18 ish.

• 12:37Speaker 02

  Yeah, exactly. They can get it in a wheelhouse. Sometimes you can learn a little bit about someone's ethnicity. Because you know, some ethnicities have teeth that are a little different. Apparently some Native Americans and some Asian people have incisors that have scooped out backs.

• 12:56Speaker 02

  You can determine. And sometimes some socio-economic background. If there's, you know, a lot of really expensive restoration work, that'll tell you that they probably had a lot of money. Or, you know, at least money to afford that.

• 13:08Josh Clark?

  Right.

• 13:09Speaker 02

  Also, the methods that are used, are used in some parts of the world and not in others, like some geographic areas. Person's lifestyle, like if they were a smoker. This is kind of fun. If you're a pipe smoker, or if you play the bagpipes, you have a very distinctive wear pattern on your teeth.

• 13:27Josh Clark?

  Did you see any pictures of a skull with a wear from pipe smoking?

• 13:32Speaker 02

  Yeah.

• 13:33Josh Clark?

  It's crazy. It's like the person's teeth like curve up. At some point, like on basically, I think it was the right side of their face, just from holding a pipe in their teeth for years and years and years.

• 13:46Speaker 02

  Yeah. And then just sort of the obvious stuff, like a family member saying like, no, they were definitely missing that tooth. Or that, you know, that distinctive crown with the diamond CWB for Charles W. Chuck Bryant.

• 14:01Josh Clark?

  I know, I can't believe you got that still.

• 14:03Speaker 02

  That was definitely their mouth. Or that tooth was broken. So beyond just dental records, like family members can sometimes help out.

• 14:12Josh Clark?

  I also saw another lifestyle one with something called a tailor's notch. This is pretty arcane. But if you find a tailor's notch, there's a chance that this was a dressmaker, a tailor, something like that, because they hold pins in their mouths.

• 14:26Speaker 02

  Oh, yeah, yeah.

• 14:27Josh Clark?

  As part of their profession, usually in their teeth. And when you do that enough times, it actually wears a little indentation in the tooth that you normally hold the sewing needle in. So do you want to talk about the Black Death or just keep moving on?

• 14:41Speaker 02

  Uh, let's take a break.

• 14:43Josh Clark?

  Okay.

• 14:44Speaker 02

  All right, we'll take a break and we'll talk about the Black Death and then dive into the more controversial bite mark analysis.

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• 17:45Josh Clark?

  So we promised to talk about the Black Death. Apparently, one of the high-profile,

• 17:52Josh Clark?

  I guess, forensic dentistry cases recently was a study that looked at the teeth of, or I think it extracted DNA from the pulp of the teeth of medieval villagers who died from the plague. And I guess they were able to exclude the plague in some cases. Like, people had died and it was falsely attributed to a death from the plague. That seems almost inconsequential to me because the other thing that they did was definitively prove that Yersinia pestis, which is a bacteria, I think a bacteria that's carried by fleas typically. So the rats came to town, the fleas were on the rats, the bacteria was on the fleas. And that's what spread the Black Death. That's what they've long said.

• 18:37Josh Clark?

  And they extracted that from the DNA of the pulp of teeth of medieval people who died from the plague, definitely died from the plague. And said, yep, here's your smoking gun. There's your problem.

• 18:50Speaker 02

  Yeah, and with something this old, if DNA isn't readily available, M-DNA, mitochondrial DNA can also be very useful.

• 18:57Josh Clark?

  And I also saw the oldest tooth that they successfully sequenced a genome from by extracting DNA from the pulp was 6,000 years old from about 4,000 BCE. Back in 2005, they managed to do that. And you know those people are still talking about like, hey, did I ever tell you about the 4,000 BCE tooth we extracted DNA from?

• 19:17Speaker 02

  Yeah, oh, boy, the smell of that tooth pulp.

• 19:20Josh Clark?

  Oh, God.

• 19:22Josh Clark?

  Good God, that was awful. I was not expecting that.

• 19:26Speaker 02

  All right, so now, this is where things get a little hinky, because we're gonna talk about the other aspect of forensic dentistry, which is the very controversial, very complex bite mark analysis, which, and we'll get to the admissibility of it now in a bit, but they still do collect the evidence, which, you know, you should do. I don't think anyone's saying like, "Hey, stop even doing this," as far as evidence collection goes. But here's how they do that. If you see a bite mark, or anything you think is a bite mark, in a murder case, let's say, you call in that forensic dentist, who's just sitting around, like, so happy they don't have their hands in a live human being's mouth at the time.

• 20:08Josh Clark?

  Right.

• 20:09Speaker 02

  And they gotta do it quick, because time is of the essence, because bite marks can change a lot, pretty quickly, especially if a body has been deteriorating for a few days. Like, the location of that bite may be entirely different, because the skin is slipping and shrinking.

• 20:25Josh Clark?

  Yeah, that's a big one. Also bruising and lividity can also obscure a bite mark, or change it, or alter it. So, they often have to wait for the bruise to heal if the human's still alive, or wait for the lividity, the pooling of blood to just kinda come and go, before they really examine it.

• 20:46Speaker 02

  Yeah. They're gonna take pictures with a ruler next to it. You've probably seen that in some movies.

• 20:51Josh Clark?

  I have. I saw it in Silence of the Lambs.

• 20:53Speaker 02

  Right. Oh yeah, that's right. Bite photography is very specific and very precise, or at least it should be. And then you can magnify those photos and stuff. But while they're doing this, the first thing that they're gonna identify is like, was it a human bite or not? And, seems like a no-brainer, like, I could even tell.

• 21:11Josh Clark?

  Sure.

• 21:12Speaker 02

  But you found a study from 2015 that doesn't quite hold up. I mean, that's about animals and human differences, right?

• 21:18Josh Clark?

  Yeah, there was a 2015 study that found, they used 39 experts. These were board-certified forensic odontologists, or members of the American Board of Forensic Odontologists, the accrediting body. I don't know why I went into that much detail, but there you have it.

• 21:38Speaker 02

  They're the official people.

• 21:39Josh Clark?

  In this study, with this 39 experts, they showed 100 photographs of bite marks, and said, "Okay, we want some information about this." Are these, let's just start with, is this a human bite mark or an animal bite mark?

• 21:51Speaker 02

  Yeah, the easiest thing in the world, was this a dog or an adult human biting this person?

• 21:57Josh Clark?

  Exactly. And only 8% of the photographs, so 8 of 100 photographs, I just did that math and I'm quite confident it's correct.

• 22:06Speaker 02

  Yeah, you nailed it.

• 22:07Josh Clark?

  Could 90% of those experts, I don't know what 90% of 39 is, come to consensus that yes, this is definitely human, or yes, this is definitely animal?

• 22:18Speaker 02

  That's hard to believe.

• 22:20Josh Clark?

  Yeah, they did not agree on the other 92 photographs.

• 22:24Speaker 02

  Yeah, I would think human and animal would be pretty easy to tell the difference of, you know, apparently not.

• 22:30Josh Clark?

  Yeah, especially if the animal's wearing human dentures at the time.

• 22:34Speaker 02

  Right.

• 22:36Speaker 02

  Good point.

• 22:38Josh Clark?

  Yeah, like that, you know, that cartoon wolf from the old timey 1930s cartoons?

• 22:44Speaker 02

  I don't think I know that.

• 22:45Josh Clark?

  Oh, sure you do. He was always like, his eyes would pop out of his head and like, he was a wolf, you know?

• 22:49Speaker 02

  Yeah, yeah, I got you.

• 22:52Josh Clark?

  So what else, Chuck?

• 22:54Speaker 02

  Well, this is a pretty disturbing, but I guess helpful thing that I never knew. After they inspect the body for the bite marks and all that stuff, they will actually cut out the bite mark and preserve it.

• 23:08Josh Clark?

  They're like, can I take this home?

• 23:10Speaker 02

  Yeah, so they will cut the bite mark from the skin, preserve it in formaldehyde, and then make a silicone cast of the bite mark, which makes total sense. I just never thought about how gross that would seem.

• 23:22Josh Clark?

  Yeah, it is pretty gross. I mean, the whole process from start to finish is fairly gross in that case.

• 23:28Speaker 02

  What kind of bite marks, though, can they make?

• 23:30Josh Clark?

  Well, they classify them based on the kind of transfer pattern is what they call it. And it's not just specific to forensic odontology. Transfer patterns are what you're looking at when you look at the rifling on a bullet to try to identify what gun it came out of, which also apparently is junk science. Fingerprints, you're transferring your fingerprints, so it leaves a transfer pattern. Same thing with forensic odontology, and the different kinds of forensic patterns are based on the damage that the bites do. So if it scrapes, like if you're, I don't need to put it any other way, that's considered an abrasion bite.

• 24:07Speaker 02

  Yeah.

• 24:07Josh Clark?

  An artifact is when...

• 24:10Speaker 02

  Yeah.

• 24:10Josh Clark?

  Yeah, when there's an actual part of the body missing from because of the bite. It's not just a bite mark. There's actually tissue or something missing, like an ear lobe, I think, is like Evander Holyfield's ear lobe.

• 24:23Speaker 02

  Yeah, I was about to say Mac Tyson bite, so.

• 24:26Josh Clark?

  He's got a fight on Friday.

• 24:28Speaker 02

  Oh, is he fighting that guy Friday?

• 24:30Josh Clark?

  On Netflix.

• 24:32Speaker 02

  Ah, shoot, I'm not even gonna be here. I wanted to see that.

• 24:34Josh Clark?

  I'll tape it for you on the VCR.

• 24:36Speaker 02

  You can tape it, alright, send me the tape. Uh, we also have, uh, volvulations. That is, um, when just some of the skin is removed, and I guess not a, an entire piece of the body.

• 24:46Josh Clark?

  Mm-hmm.

• 24:47Speaker 02

  Uh, you have contusions, which is of course a bruise. Uh, if it's profusely bleeding, it's a hemorrhage. If it's a nice, clean, neat wound, then you have a very precise biter, and they call that an incision. And then a puncture wound is a laceration.

• 24:59Josh Clark?

  Yes. Uh, and then there's also, um, the different, like, depths or the, the, um, obviousness of the bite mark is another category that they use. Um, and it starts from lowest to highest. It took me a minute to figure this out, because I don't think the wording they used is really good.

• 25:17Speaker 02

  Agreed.

• 25:18Josh Clark?

  A clear impression means that there was significant pressure used. That's the lowest of the three categories.

• 25:25Speaker 02

  Yes.

• 25:25Josh Clark?

  An obvious one signifies medium pressure, which that to me just, just like shows that this is not accurate science. Medium is the, a type of fry order, French fry order, not the, the, you know, depth of a bite mark. Like, medium is so subjective, right?

• 25:44Speaker 02

  Yeah.

• 25:45Josh Clark?

  All three of these are, and then noticeable, that seems to me like that would be the, the least of the three. That's the, the most, um, the, the most pronounced bite mark of all, um, because the biter used violent pressure to bite down.

• 25:59Speaker 02

  Yeah, it should be.

• 26:02Speaker 02

  Obvious, oh my god, and holy crap for the love of god, what was this person doing?

• 26:09Josh Clark?

  Yeah, for sure. There's also some, um, some other things that the biter can do during the biting, uh, if they, you know, if they like use their jaw a bunch, it's not just like one bite where they clamp down. If they bite in succession a few times, that is gonna leave a totally different mark from one that is going to, where they just clamp their jaw down or something. Uh, if they move their tongue, it will move the skin around and will affect the bite mark that's left behind. We should have probably given like a heads up at the outset of this episode, huh?

• 26:45Speaker 02

  Well, I think forensic dentistry is a creepy enough title, or maybe I'll title it forensic dentistry colon, uh, enter at your own risk or something like that.

• 26:53Josh Clark?

  Oh, good one. And then there's another one too. If the victim is being, is still, in my, which to me means dead, because nobody's gonna sit still while they're being bitten hard enough to leave a bite mark that could be used against you in court. But that, you know, if they're moving, that's going to affect the bite mark that's left behind too. And then of course also the kind of, um, tooth profile they have too, right?

• 27:16Speaker 02

  Yeah, for sure. I mean, if you're, uh, if I would have bitten somebody in a violent episode when I had, um, my front tooth or my two front teeth missing, it would be pretty obvious when you saw that bite mark. Uh, Ted Bundy, like you said, had crooked teeth, and so that will leave a crooked impression. Um, obviously any chips on your teeth, uh, are gonna make a more sort of jagged impression.

• 27:40Josh Clark?

  Yeah, like if you ate a bunch of chips and they're just stuck between your teeth?

• 27:45Josh Clark?

  Is that what you meant?

• 27:47Speaker 02

  Yeah. Here's a ear lobe and some Dorito, so let's put that in an evidence baggie.

• 27:53Josh Clark?

  You're welcome, Dorito, for the plug.

• 27:56Speaker 02

  And then braces, you know, if you have braces or implants or something, or a bridge, that can leave a pretty distinctive impression.

• 28:03Josh Clark?

  For sure.

• 28:05Speaker 02

  Once, and this is sort of how it used to work, but once they identify a subject, they're going to get a warrant to take a mold of a suspect's teeth so they can compare it. They'll take a lot of pictures of their mouth and stuff, opening, closing, biting, stuff like that. And then, in the old days, they would go to court and compare those, and a forensic dentist would take the stand and say, "Hey, that bite mark looks like that person's mouth to me, jury. That can be a major reason why you convict."

• 28:36Josh Clark?

  And in some cases, they would say things like, with 100% certainty.

• 28:41Speaker 02

  Yeah.

• 28:42Josh Clark?

  Another thing that they say too, that we'll find that seems to not be at all true, is that each person's arrangement in teeth, like your mouth, everything inside of your mouth, is totally unique, like your fingerprints. And that apparently is not true at all, but you'll find it all over the internet as fact.

• 29:01Speaker 02

  Yeah, I mean, there are some professional dentists and forensic dentists that still believe that. I mean, that thing I sent you was from last year.

• 29:11Josh Clark?

  Yeah.

• 29:12Speaker 02

  And is on the National Institutes of Health US government website, and those four accredited dentists, dental experts, flat out say like, "A person's bite mark is unique, like DNA or fingerprints," when, and I guess we should probably take a break and get into the studies and stuff like that.

• 29:30Josh Clark?

  Right.

• 29:31Speaker 02

  But it seems like study after study has kind of confirmed that it's just not the case.

• 29:35Josh Clark?

  Yeah. Well, let's take that break, and we'll come back, and we'll talk about all the controversy surrounding bite mark analysis as a part of forensic odontology.

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• 32:56Speaker 02

  All right. So you did some extra digging and it was pretty clear from doing the research that this is basically known as junk science now to most people, despite those four people who wrote the article on the National Institutes of Health.

• 33:10Josh Clark?

  Right.

• 33:11Speaker 02

  But there was a review in 2022 in a report from the NIST. What does that stand for?

• 33:19Josh Clark?

  The National Institute of Standards and Technology. They're like a federal agency, if I'm not mistaken.

• 33:25Speaker 02

  Yeah, okay. So they released this report that said, and there were previous reports that we'll talk about too, I guess, but this is the most recent, that said bite mark analysis is not real science. And it's based on these three sort of faulty premises. One, which you already mentioned, which is that a person's dental pattern is unique to that person. And you know, there haven't been any studies that really confirmed this. There was a 2013 study from the United Arab Emirates that found, and I think there's, is that a sort of a dental?

• 34:02Speaker 02

  Capital of the world because I saw a lot of dentists from like Saudi Arabia.

• 34:06Josh Clark?

  Oh, really?

• 34:06Speaker 02

  UAE, yeah.

• 34:07Josh Clark?

  No, I didn't know that. I didn't see that. Maybe.

• 34:10Speaker 02

  I have a hunch that that's the case. So maybe someone will confirm or deny that. But that study found that 51% of the 2,000 dental charts they examined were unique. So one more than half and the rest were identical to at least one other. Uh, the only thing I'll say in defense is that it may not be truly unique. But if 49% are unique, then that's unique enough to talk about. Maybe not to be used in court, but enough to talk about.

• 34:42Josh Clark?

  Yeah, yeah.

• 34:43Speaker 02

  In my opinion.

• 34:44Josh Clark?

  Yeah, for sure. But the, the fact is that study, and we should also caveat that with the fact that this study used dental charts only. And they made sure that they were highly, high quality dental charts that they examined. But the fact that they were able to find dental charts that were identical between two people totally undermines the, um, the idea that everybody's mouth is, is unique. Everybody's teeth arrangement is unique.

• 35:14Speaker 02

  Seems like about half of them are.

• 35:15Josh Clark?

  Yeah.

• 35:16Speaker 02

  If you go by the data here.

• 35:17Josh Clark?

  Yeah. And this was 2,000 dental charts. They didn't choose like three. Like this was a, a pretty decent, high, high quality study. And, um, yeah, I think it totally undermines that. But like you said, yes, there's also enough uniqueness that you can kind of use this. And I think like you said, nobody's really saying like, stop doing bite mark analysis entirely.

• 35:39Speaker 02

  Right.

• 35:40Josh Clark?

  The, um, and the, actually in their defense, the American Board of Forensic Odontology says, they basically admit like, hey, we've made some mistakes in the past. We've cleaned up our act. We've revised our guidelines. And now, if you're a legitimate forensic odontologist, the furthest you will go is, um, to make three different calls. One, exclude, meaning that this person's teeth could not have possibly made the bite mark that you're showing me, cops.

• 36:11Speaker 02

  Yeah.

• 36:12Josh Clark?

  Not exclude, which is only saying it's possible. I'm not going to go any further than that, but it their their teeth resemble enough. This bite mark pattern, this bite pattern, that it's possible that this person made it. And then inconclusive. And that's as far as they're supposed to go. They're not supposed to, in that sense, they're not, I guess you could testify those three things. But if the prosecutor is like, OK, so so not exclude, you're saying it's his, right? They're they're supposed to bail essentially at that point. They're not supposed to go any further than that. That's the standard in the guidelines for forensic dentists doing bite analysis, bite mark analysis today. But there's still plenty of people out there who are going beyond that.

• 36:55Speaker 02

  Yeah, and you know, that's the kind of situation, too, where you also have to really educate a jury over like the data on what that really means. You know what I'm saying?

• 37:06Josh Clark?

  Mm hmm.

• 37:07Speaker 02

  And say like, hey, half the time, these aren't unique. So you have to understand that going in. So you know, that that was the first thing. And you know that there was that one case that you sent where, and this kind of factors into number two, and number one was that they're the unique. Number two is that the patterns can be accurately transferred to the human skin. Because we've already talked about the fact that there can be a lot of distortion by skin's elasticity. And if the person like sort of does a sawing motion, it completely distort the the bite mark. But you sent that one case to the guy who was convicted, who was missing a tooth entirely, which should show a pretty clear like, hey, we can exclude this one because the bite mark didn't have a gap.

• 37:52Speaker 02

  But the they were like, yeah, but if he grinded his teeth and kind of did a sawing motion, it could look like this. And he was found guilty, you know, and he was not guilty.

• 38:01Josh Clark?

  Yeah, he was sentenced to jail, I think. Was that Roy Brown?

• 38:05Speaker 02

  Yeah, in 2007.

• 38:06Josh Clark?

  OK, so, yeah, he spent almost 20 years in jail, 15 years from 92 to 2007, largely based on that that bite mark analysis testimony.

• 38:18Speaker 02

  Yeah, and and the both forensic dentists that worked on that case recanted their testimony.

• 38:24Josh Clark?

  Right.

• 38:24Speaker 02

  Like completely.

• 38:25Josh Clark?

  Yeah, that was a big one, too. I think maybe in one of those cases where they were appealing it, I don't know if it was Roy Brown's, but there have been plenty of forensic odontologists who've gone back and been like, what I was saying apparently is not right or grounded in science. I recant my testimony. And at least one judge that I read was like, well, we didn't really need you. The jury could have come to the same conclusion that the bite mark matched their teeth. So I'm not going to overturn this case, which is nuts in and of itself. But Roy Brown is far from the only person who has been exonerated after being convicted on bite mark analysis, too, right? Like, haven't there been like at least 26 people?

• 39:06Speaker 02

  Yeah, at least 26 that DNA evidence is now cleared where bite mark analysis was, if not the smoking gun, like a pretty key part of the jury's, you know, findings.

• 39:16Josh Clark?

  Yeah, remember when I was saying some expert witnesses on the stand say like this, it's 100% match? That happened to a guy named Roy Krone. He did 10 years based on bite mark analysis because you got to understand if you're a juror and the prosecution is saying like this person is an expert in forensic odontology and that expert tells you, the jurors, there is 100% match between that man's teeth and this bite mark on this murder victim. It's going to be tough to overlook that for the average juror, I would guess.

• 39:49Speaker 02

  Yeah, for sure. And, you know, the big change that you were talking about with just excluding, that came about in 2016. We've mentioned some other studies. There was one we didn't mention in 2009, when the National Academy of Sciences released a report about a lot of problems with a lot of forensic science, but one of those was bite mark analysis. And they basically said, and this was in 2009, and it still took until 2016 to make that change official, was they said there's no scientific studies that support the assertion that bite marks provide sufficient detail for positive identification. And then a few years after that, doctors from the American Board of Forensic Odontology, like we said, that's sort of the main body.

• 40:33Speaker 02

  Or is the main body. Participants in a study there of certified dentists, overwhelming number of them couldn't even agree whether they were looking at a bite mark at all.

• 40:43Josh Clark?

  Yeah, there was another thing too, I think from that same study where they took the same experts and went back to them eight weeks with the exact same photos they'd shown them eight weeks before. And some of those experts didn't even agree with their previous assessments.

• 40:57Speaker 02

  Wow.

• 40:57Josh Clark?

  Yeah, so that was, and they weren't like, hey, you said this before, what do you think now? It was like, they, I think they thought that this is a new set of bite marks and they were just basically guessing is what they found. So it's been pretty thoroughly debunked. But people still use it. The Innocence Project has really taken an interest in this, and I think rightfully so. We did an episode on that with guest Paul Azan.

• 41:24Speaker 02

  Yeah.

• 41:24Josh Clark?

  Remember correctly.

• 41:27Josh Clark?

  And yeah, so they're a group that go around and basically try free people who were railroaded or wrongfully convicted. Usually based on DNA evidence that wasn't heard in their case. And so one of the things that they've done is taken interest in bite mark analysis. And one of the roles they play now is, I don't know how they keep their finger on the pulse, but if a prosecutor, which is very rare these days, from what I understand, tries to introduce bite mark analysis into a case, the Innocence Project will show up and be like, we object to that. This is not science. This should not be.

• 41:58Speaker 02

  Yeah.

• 41:59Josh Clark?

  Admitted. And I think they're fairly successful.

• 42:02Speaker 02

  They throw tomatoes at them.

• 42:03Josh Clark?

  For sure.

• 42:05Speaker 02

  There was another case you found, a pretty striking one, a guy named John Kunko. He was convicted of rape and assault in 1991. And the main evidence that got him convicted was identification of his voice by the victim. A comment he supposedly made at a party and then bite marked on the victim's shoulder.

• 42:28Speaker 02

  All the evidence was a problem. The comment that the party that he supposedly made was not corroborated by, I always have trouble with that word.

• 42:36Josh Clark?

  It's a hard word.

• 42:37Speaker 02

  Corroborated by any other people at the party. The voice ID was made from a police officer's imitation of Kunko and his lisp to the victim. So I have no idea how that got through.

• 42:50Josh Clark?

  Yeah.

• 42:50Speaker 02

  And then I believe the bite mark was infrared light analysis of a bite mark that had already healed.

• 42:59Josh Clark?

  This is a big one. So there is a forensic odontologist from Mississippi named Michael West. And he essentially just changed careers to be an expert witness in forensic odontology. That's how he made his living. And he came up with a technique called the West phenomenon wherein you can, according to him, using some special goggles and a UV light, you can basically resurrect a bite mark that's healed years later and see it well enough that you can compare it to a suspect's bite and use it to convict. He totally made it up. Apparently, at least in the first case that he used it on, he took photographs, but he wouldn't share them with anybody.

• 43:42Josh Clark?

  So it was just his testimony that this person was convicted on, and it became a tool of the trade. So other people, including John Kunko, were convicted in part because of this West phenomenon, which is part of overall junk forensic science. So this is the junkiest of the junk that people were being convicted on.

• 44:01Speaker 02

  Did he also sell the special goggles on his website?

• 44:03Josh Clark?

  Yeah. But he sold them as X-ray goggles that you could look right through people's clothes with.

• 44:10Speaker 02

  Yeah, there was a picture of him with his, looking at his hand and the bones.

• 44:14Josh Clark?

  Yeah, with exclamation points coming off of his head.

• 44:18Speaker 02

  Yeah. So yeah, I mean, this is, everything changed in 2016. One of the big things that happened, I think there was a case in Texas, a guy named Stephen Cheney was released by the Texas Court of Appeals. And this is the Texas Court of Appeals. They're not big on releasing, you know, convicted criminals.

• 44:36Josh Clark?

  I noted that, too.

• 44:38Speaker 02

  But the Texas Forensic Science Commission in 2016, because of this, you know, kind of fraudulent bite mark evidence in Stephen Cheney's case, they were like, we need to stop this. And I think that was kind of a big case that kind of, you know, really jumpstarted the whole, we maybe not scrapped the whole thing, but where they ended up, which is it can exclude, but it can't positively identify.

• 44:59Josh Clark?

  Yeah. You just use it to exclude. That's what most people can agree on for bite mark analysis is as far as they'll go.

• 45:04Speaker 02

  Yeah.

• 45:06Josh Clark?

  Chuck, did I ever tell you about Paul Revere in forensic odontology?

• 45:12Speaker 02

  No, but hey, it's a good little historical cherry on top, right?

• 45:16Josh Clark?

  Yeah. So Paul Revere, in addition to being a blacksmith, he was a dentist, too. And one of the things he did, he was one of the first forensic odontologists who used dental records, based on his own knowledge, too. He made, you know, dental work for a lot of people in the Revolutionary War. And he identified some of those people, including Dr. Joseph Warren, the man who sent him on his fateful ride where he shouted, "The British are coming, the British are coming."

• 45:43Speaker 02

  Bing pow!

• 45:45Josh Clark?

  Yeah, pretty amazing, huh?

• 45:47Speaker 02

  Yeah, that's a good one.

• 45:48Josh Clark?

  Thanks. I think that's it for forensic odontology, right?

• 45:52Speaker 02

  Yeah, and man, that may be it for our long, long-running forensic suite. I can't believe that there could be anything else, but I also said that last time.

• 46:01Josh Clark?

  Yeah, I disagree, but yes, we'll find out.

• 46:04Speaker 02

  You think?

• 46:04Josh Clark?

  I'm going to go find something.

• 46:07Speaker 02

  Maybe. I mean, someone will write in and be like, guys, you've covered crime scene cleanup, blood spatter analysis, fingerprinting, DNA. I mean, the list goes on and on.

• 46:14Josh Clark?

  Yeah, you forgot forensic footsmelling.

• 46:16Speaker 02

  But you're making one I didn't know about. That's it. It was the dog. I smell Fritos.

• 46:21Josh Clark?

  Right, nice. Oh, actually, I can do this old school, too, because if you want to know more about forensic dentistry, you can go check out a How Stuff Works article that we used in part for this episode. That is kicking it old school, isn't it?

• 46:34Speaker 02

  Yeah, one of the rare articles that we didn't cover that is still good for us.

• 46:38Josh Clark?

  Yeah, and since I kicked it old school, then it's time for listener mail.

• 46:45Speaker 02

  All right, I'm gonna call this another ADHD follow-up. This is a, this is a good one. Hey, guys, I had to write in after the ADHD episode during the first episode. I had to pull over into a parking lot because, honestly, guys, I started crying.

• 46:58Josh Clark?

  Oh, wow.

• 46:59Speaker 02

  Yeah. I have ADHD and I have never had my life explained on a podcast before. Everyone's experiences are different, for sure, and I think you did an incredible job explaining the base challenges. I also appreciated Chuck's hesitancy to call it a disorder. It is defined as a disorder, but, so there's nothing wrong medically with calling it one, but it does hurt just a little, even as an adult, when people call it a disorder without thinking about the person who has it. I appreciated the optimism with which you both spoke about the challenges and how they can be managed, especially Josh. The only thing I would add to that is the subtopic would be to find people who accept you before they try and change you.

• 47:42Speaker 02

  When I feel that people love and accept me as me, I am far more willing to accept their help with managing my ADHD. Don't approach someone like you're gonna fix them. Approach them because you love them, and they will receive your honest offer to assist.

• 47:56Josh Clark?

  Man, that is some good ADHD advice right there.

• 47:59Speaker 02

  And just good life advice. Your podcast reminded me that there are a lot of people out there like me, and I hope that a lot of people out there who are trying to take this particular challenge do amazingly positive things with it, and that is from Steve.

• 48:13Josh Clark?

  Thanks a lot, Steve. What a great email.

• 48:15Speaker 02

  Yeah, appreciate it, Steve. That, uh, those episodes were a big deal for us, for a lot of reasons, and it seems like people responded, so we're proud of them.

• 48:24Josh Clark?

  For sure. If you wanna be like Steve and tell us that you had to pull over because you were so overcome by something we did or said, we love that kind of thing, especially if it's positive, not because it was so terrible that you had to pull over. But even if that was the case, you can still email us. Either way, send it off to [email protected].

• 48:47Speaker 03

  Stuff You Should Know is a production of iHeartRadio. For more podcasts, iHeartRadio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.

• 49:02Josh Clark?

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