What are teeth?
Teeth are structures of the digestive system that enable us to properly chew our food aiding in its eventual breakdown.
Are teeth bone?
No. Although somewhat bonelike in appearance, teeth cannot produce red blood cells. Teeth are composed of four tissues:
*Enamel is the outer, white layer of the teeth. Enamel is the hardest substance in the human body, allowing the teeth to withstand a lifetime of grinding.
*Dentin is the second layer. Similar to bone, this yellowish material carries some nerve fibers and forms the bulk of each tooth.
*Pulp is the tooth’s soft center. It contains blood, nerves, and lymph vessels. Pulp is the center of nourishment and nerve interaction between tooth and brain.
*Cementum is a hard, bone-like material that covers the majority of the root of a tooth and helps connect the tooth to its jaw socket.
There is also a Periodontal Ligament, which lies between the cementum and the jawbone, and acts as a shock absorber.
How many teeth are there?
Humans have two sets of teeth. The first set, the deciduous teeth of children begin forming during gestation. After teething, children have 20 teeth. The mouth can be separated into quadrants (e.g. upper-right, lower-left); in each quadrant, there will be five teeth: central incisor, lateral incisor, canine, first molar, and second molar.
Between six and 12 years, the deciduous teeth are replaced with permanent teeth. Eventually the set of permanent teeth will contain 32 teeth, although the third molars (wisdom teeth) may not come in until an individual is in their twenties, if they come in at all. The jaw of modern humans has become smaller, often necessitating the removal of impacted third molars. The quadrants of the permanent dentition each include: central incisor, lateral incisor, canine, first premolar, second premolar, first molar, second molar, and third molar (wisdom tooth).
What is dental morphology?
Dental morphology is the study of the form and structure of the teeth. Basically it’s all about how teeth “look.”
Big deal. What is it good for?
Dental morphology is especially useful as a comparative study. Using living and skeletal samples, databases of population characteristics can be formed. Using these databases, a skeletal sample of unknown origin can be assigned a probable ancestry based. In a forensic setting ancestry (“race”) is vital to narrowing down the possible identifications of an unknown individual. There is of course lots of fancy math involved, but the simplest way to explain it is as a comparison of known to unknown.
What kind of things are compared?
Metric and non-metric traits. A metric trait is one which can be measured, such as tooth length or enamel thickness. Non-metric traits have more to do with the “look” of the tooth. There are some traits or abnormalities that show up more consistently in some populations than in others. These traits are “measured” and a scale of “there-to-not there.” There are no real numbers involved, it’s all relative.
What are some examples of non-metric traits?
Some common non-metric traits include Carabelli’s trait and Incisor-Shoveling
Carabelli’s trait is also known as Carabelli’s tubercle or cusp. The first report of this trait was published by the Austrian court dentist Georg Carabelli in 1842. This trait consists of an additional cusp on the mesiolingual surface of the upper molars. Like any non-metric trait, Carabelli’s may be completely absent or may be present in continuous variation or grades of severity. Typically a reference plaque with several grades of severity will be used to determine the “grade” an individual should get. Bearing in mind the relative nature of the measurements, it can be said that a higher percentage of people with European ancestry will display a larger expression (i.e. grade) of Carabelli’s trait.
Shoveling is found in incisors, and occasionally canines. The marginal ridges of the teeth are prominent, lending a shovel-shaped appearance to the lingual surface of the tooth. This trait is found frequently in persons of Asian descent, including American Indians and Eskimo/Inuit.
You talk funny. What do all those terms mean?
Terms such as mesiolingual are common dental terms used by dentists, anatomists, anthropologists, anyone with a need to describe the location of teeth or traits on teeth.
· mesial refers to the surface (edge) of the tooth that is closer to the midline (think nose).
· distal refers to the surface (edge) of the tooth that is more distant from the midline (think closer to the ear).
· lingual refers to the surface of the tooth closest to the tongue.
· buccal refers to the surface of the posterior teeth (premolar and molar) that is near the cheek.
· labial refers to the surface of the anterior teeth (incisor and canine) that is near the cheek and lips.
· occlusal refers to the biting surface of the posterior teeth.
· incisal refers to the biting surface of the anterior teeth.
· contact areas are areas that touch the adjacent teeth.
So what exactly does mesiolingual refer to? By combining mesial and lingual, the lazy writer can quickly refer to the surface of the tooth next to the tongue, which is also closer to the midpoint of the face.
So ancestry, isn’t that just race?
No. Race is a social construct, there is no biological justification. Ideas of “race” differ from culture to culture. An individual identified as “black” in modern American (U.S.) culture might be identified as “white” in Puerto Rico. Avoidance of the term race isn’t just political correctness—it is an attempt to avoid confusion (especially important when working in an international context). A more appropriate term is “ancestry” Race is the group with which the individual “would have likely been identified in their community.” We want to know the likely descent of the individual we’re looking at. If we know that, we can better determine what they may have looked like (necessary to identify a skeleton). Using probable ancestry and forensic and anthropological databases, a worker can determine a height and weight range for a skeleton. Ancestry is also vital information for facial reconstruction.
"Mortification builds character." -J.D. Robb
Shoveling is most common on the upper central incisors (right smack in the middle of your face, under your nose). The edges of the teeth, closest to the tongue (hence lingual) build up, creating ridges around the center of the tooth. This trait is common in people of Asian descent, including American Indians.
