I'm pretty sure I sent this to the group but just in case I didn't here
it is again,
joseph
ps: happy holidays. One possible approach for the following info is to
contact your local university dental school and try to find a "budding"
dental student that might be interested in examing your teeth in search
of the discussed characteristics:
(http://gladstone.uoregon.edu/~grobbins/huh.html)
Dental Discrete Traits In The Permanent Teeth
The populational frequencies of dental discrete
traits
can be compared to determine relatedness. Twin studies and animal
breeding
research have proven high heredity for non-metric traits though the
precise
genetic mechanism is not well understood. The evidence for relatedness
must be corroborated by convergent evidence from metric traits,
analysis
of skeletal traits, other genetic and/or serological evidence,
archaeological,
geographical and historical evidence as well as linguistic
phylogenetics.
This study will supplement research on the metric trait analysis and
act
as a foil to the historical record. The traits used in this study are
outlined
in Hillson (1996) and they were scored based on a system developed at
ASU
be Christie Turner, et al. (1991). The Turner system includes
standardized
reference plaques, terminology, and scoring charts to minimise the
effects
of observer error. The following is a written summary of the dental
discrete
traits and I am developing a link to photographs of some of the
reference
plaques. The plaques reflect the fact that the traits are really
quasi-continuous
and are divided into grades of _expression_.
Shovelling
Shovelling is most commonly found in maxillary incisors
but can also be present in the mandibular incisors and sometimes in
canine
teeth. The ASU system has defined six grades of shovelling in the
central
incisors, seven in the lateral incisors, and six grades of double
shovelling.
The term "shovel-shaped" was coined by Hrdlicka (1920) to describe
anterior
teeth with a deep fossa on the lingual surface created by large
marginal
ridges, a normal morphological feature which has been exagerated in
cases
of shovelling. Double shovelling refers to a ridge on the labial
surface
of the tooth which may or may not occur in addition to the lingual
ridge.
Populations from Asia and Native America generally have the highest
frequencies
of shovelling with occurances in up to 90 % of the population.
Carabelli's Cusp
The maxillary first molar (and occasionally the second,
rarely the third) can have an accessory cusp on the mesiolingual
surface.
This feature has grades from a small pit or ridge to a full sized cusp.
The trait can effect up to 85 % of some European populations.
Anterior Cingulum
A cingulum is a projection or ridge of enamel which in
it's most extreme _expression_, can form an accessory cusp. The maxillary
incisors and canines are scored for the presence and severity of this
trait
on the lingual surface. Grooves on the root of the maxillary incisors
are
also scored.
Maxillary Molar Cusp Variation
These traits involve reduction or absence of the
generally
large distobuccal cusp on the third maxillary molar. The scoring system
is based on whether all four cusps are present and to what size thay
have
developed.
Maxillary Molar Metaconule, Metacone, and Hypocone
There is a five stage scoring system for the
development
of the metaconule cusp (or Max Cusp 5) on the distal surface of the
maxillary
molars. The cusp grades from absent to very pronounced and often
includes
two vertical ridges. There are also five stage scoring systems for the
presence and size of the metacone and hypocone cusps. Photographs of
the
reference plaques will be especially helpful in describing these cusp
variants.
Maxillary Molar Parastyle
This feature is found on the mesiobuccal surface of the
maxillary molars and again ranges from a small pit to a full sized
cusp.
The parastyle is most common on the third molar and least common on the
first.
Mandibular Premolar Cusps
There is a lot of variability in the number of lingual
cusps on the mandibular premolars. Most commonly there is one cusp but
two or three can also be present in different size grades. This trait
is
subject to error due to occlusal wear, however most researchers leave
out
of the sample teeth that are very worn.
Mandibular Molar Cusps
The mandibular first molar generally has five cusps,
this trait describes the presence of only three or four cusps. The four
cusp variant occurs with the absence of the distobuccal cusp, the three
cusp variant is missing the distolingual cusp as well. If the five
common
cusps are present other variations exist in the presence of a sixth or
seventh cusp at the distobuccal and distolingual surfaces. These latter
two traits are rare in humans but can be more common among some of our
hominid ancestors.
Mandibular Molar Protostylid
On the buccal surface of the lower molars there can be
a protostylid ranging from a small fissure to a prominant cusp. This
trait
can be present on any of the lower molars, with higher frequencies in
the
first and third, and on the deciduous second molar.
Occlusal Patterns
Fissures in the occlusal, or biting surface of the
first
mandibular molars are generally in a "Y-5" pattern, meaning that there
are usually five cusps and a Y-shaped groove separating them.
Variations
in the shape of this groove include the “+” pattern and the “x”
pattern.
The second mandibular molars typically have four cusps and a “+”
pattern
of grooves. The ASU system has divided the variants into five grades
and
again teeth with occlusal wear should be eliminated from the sample.
Deflecting Wrinkle and/or Trigonid Crest
The term ‘deflecting wrinkle’ describes the occurance
in first molars of an "L"shaped wrinkle in the distal side of the
mesiolingual
cusp. This trait can effect up to 80 % of a given population. The
trigonid
crest is a high ridge which can develop between the mesiobuccal and the
mesiolingual cusps.
Enamel Pearls
The maxillary posterior teeth can have pearls of enamel
at the cervical margin or on the root surface. These size and number of
these enamel pearls are recorded.
Molar Root Number Variations
Maxillary premolars can have one to three roots with
the first premolar being the most variable. The degree of bifuraction,
or separation, between the roots is also scored.
Uto-Aztecan Maxillary Premolar
The anterior maxillary premolar may have an especially
prominant buccal cusp and an associated furrow on this cusp. The
_expression_
of this trait is generally restricted to Native American groups from
the
Arizona area (Uto-Aztecan refers to the linguistic category for the
area).
Distal Accessory Ridge
This trait is a measure of the size of the mesial
marginal
ridge on the maxillary canines. The mesial ridge is generally larger
than
the lateral ridge but in certain populations, such as the San, it is
generally
particularly large with an accessory ridge on the lingual surface of
the
crown.
Taurodontism This trait refers to teeth which
have
short roots and tall crowns enclosing high pulp cavities. This trait is
generally found in molar teeth and is best seen in x-ray images. The
trait
is uncommon in humans and is usually seen in Neanderthals.
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