ANTH 3997 LSU Exam 2

What are the 3 ways of noticing variation?

Race, ancestry, cline

Race

-Not an accurate representation of phenotypic variation

-Cultural concept

Ancestry

-Background

-Problem: gradients

Cline

-Variation distributed with a geographic gradation of phenotypic traits

-No hardlines

Non-metric trait

A trait that is not measured, but observed

Absence vs. Presence of Non-Metric traits

You either have the trait or you don't

How are non-metric traits observed?

With a graded scale and dental plaques (0= you don't have the trait; 5= you have the largest of that trait)

What were the three plaster plaques created to observe Carabelli's Cusp?

-1945: Dahlberg

-1963: Hanihara

-1991: ASU

Which plaster plaque was the first to recognize that populations have differing traits?

Dahlberg

Which plaster plaque is confusing because it contains too many teeth?

Dahlberg

Which plaster plaque has a scale of a-h?

Dahlberg

Which plaster plaque includes only 3 teeth?

Hanihara

Which plaster plaque has a scale of 1-7?

Hanihara

Which plaster plaque isolates the actual tooth, making it easier to see Carabelli's Cusp?

ASU

Shoveling

A dental trait of incisors in which the sides curve to make the tooth shovel-shaped

Uto-Aztecan Premolar

A dental trait of the maxillary 1st premolar in which there is an extra cusp on the buccal surface

-Presence vs. Absence trait

Distal Accessory Ridge

A dental trait of the maxillary canines in which there is an extra ridge on the distal side

-Very common; runs in the family

Carabelli's Cusp

A dental trait of the 1st maxillary molar in which there is an extra cusp on the lingual surface

-Very common

-One of the earliest dental traits to be found

Taurodontism

A dental trait of molars in which the trunk of the root is extended down and the pulp chamber is massive

-Only 0.5% of the world possesses this trait

What are the 3 applications of non-metric dental trait analysis?

-Ancestry and clines

-Relatedness of multiple people

-Migration

What can dental metrics tell us about humans?

-Gender

-Body size

-Genetics

How does dental metrics reveal gender?

Sexual dimorphism- males dentition tends to be larger than females

How does dental metrics reveal body size?

There is a correlation between tooth size and body size

How does dental metrics reveal genetics?

Tooth crown diameters are inherited, so it can show the relatedness or biological distance of one individual to another

What is a caliper?

An instrument used to take the measurements involved in dental metrics

What are the 4 different methods of measurement in which calipers are used?

-Direct measurement: used on loose teeth or teeth in the mandible/maxilla

-Microscopy: measurement of enamel thickness and other thin sections

-Photogrammetric: measurements on pictures

-Radiographs: measurements on x-rays of root length or crown size

What are the 4 basic dental measurements?

-Mesiodistal measurement

-Buccolingual measurement

-Crown height

-Root length

Where can a mesiodistal measurement be made on the tooth?

At CEJ or at midpoint of the crown or root from mesial to distal side

Where can a buccolingual measurement be made on the tooth?

At CEJ or at midpoint of the crown of root from buccal/labial to lingual side

Where should we measure a tooth for crown height?

From CEJ to tip of cusp

Where should we measure root length?

From CEJ to apex of root

What are the two types of errors in dental metric measurements?

Inter-observer error and Intra-observer error

Inter-observer error

differences between the measurements of different researchers

Intra-observer error

differences between the measurements taken by a single researcher at different times

What are the 3 things that can effect dental measurements?

-Human error

-Precision vs. accuracy

-Dental ware/problems

Precision

All results are close to each other; similar measurements every time you take them

Accuracy

How close your results are to the actual measurement

What are some dental issues can cause discrepancies in dental metric measurements?

-Interproximal ware

-Attrition

-Carious lesions

-Dental calculus

Attrition

teeth with little to no enamel; excessive ware on crown

What is the progression of an embryo?

-Embryo (first 8 weeks)

-cellular migration and differentiation

-differentiation of all major structures

-Fetus (8 weeks to birth)

-Organogenesis

Morphogenesis

the molecular signals (genes) that control cell growth, migration, and cell fate and differentiation; the outline of the entire process of how teeth (and other organs) form

-Cascade of gene expression (not just one gene that tells one thing to happen)

Patterning

spatial and temporal event whereby regional development occurs to form clear class differences between incisors/canines, premolars, and molars

What are the steps to Patterning?

1. Induction

2. Competence

3. Differentiation

What is induction (patterning)?

process that initiates differentiation

-sections of cells differentiate into incisor/canine compartment, premolar compartment, or molar compartment

What is competence (patterning)?

The ability to respond to differentiation

-either the tissue will become the right kind of tissue or it will die

What is differentiation (patterning)?

change in cell type (specialization)

What genes are important in tooth development?

-Lim-homeobox Genes (Lhx-6 and Lhx-7)

-Pax-9

-Sonic the Hedgehog Gene

-Redundancy genes

What is the function of Lim-homeobox genes?

Initialization of the dental lamina formation-- without this gene , you won't have teeth

What is the function of the Pax-9 gene?

Localization of tooth germs (each tooth has its own germ)

What is the Sonic the Hedgehog gene?

a signaling molecule that tells other steps to occur

What is the function of the SSH gene when it is released by the primary enamel knot?

It tells certain cells where they should be positioned or where they should go

What is the function of the SSH gene when it is released by the secondary enamel knot?

Regulation of cusp growth

What does the absence of SHH gene lead to?

Holoprosencephaly (mutation resulting in small incisors and molars)

What are the 3 different Heterodonts?

-Incisiform (incisors)

-Caniniform (canines and premolars)

-Molariform (molars)

What are the stages of dental development?

1. Bud stage

2. Cap stage

3. Bell stage

4. Erupted tooth

What happens during the bud stage?

-The first epithelial incursion into the ectomesenchyne

-Cells have not changed shape or function at this point

-Tightly packed ectomesenchyne surrounding bud

-Tooth buds form at EVERY location where a tooth will form, for deciduous and permanent teeth

What happens during the cap stage?

-Tooth bud begins to take on cap-appearance

-Cap is also called dental organ or tooth germ

-Cap is also called the enamel organ because it turns into enamel

-Below the cap is the dental papilla which will eventually be the dentin + pulp chamber

-Dental follicle

-Onset of morphological differences between tooth germs

What happens during the bell stage?

-Enamel organ/cap resembles a bell

-Crown assumes final shape

-Morphodifferentiation: differentiation between different tooth types

-Formation of ameloblasts (enamel) and odontoblasts (dentin)

-Enamel moves upward and dentin moves downward

What is the dental formula for deciduous teeth?

2:1:0:2

Which tooth types are missing for deciduous teeth?

premolars and a molar

How many deciduous teeth are there?

20

Succedaneous teeth

adult tooth that replaces a baby tooth

Which teeth are considered succedaneous?

Adult incisors, canines, and premolars

What are the 4 functions of deciduous teeth?

-Mastication when young

-Facial support

-Formation of clear speech

-Spacing and arch continuity

Turner's Spots

Dental problem in which if a child has a serious cavity on a baby tooth and the infection goes deep into the mouth, a yellowish spot (dentin peeking through) develops on the permeant tooth that follows

Retained deciduous teeth

baby teeth haven't fallen out, but adult succedaneous teeth grow out on top of them; happens because roots were not signaled to dissolve

What is the general progression of deciduous and adult tooth growth?

1. Crown calcification

2. Root formation

3. Emerge

4. Deciduous root completion

5.Exfoliation (root resorbs at apex)

6. Occlusal migration of permanent teeth

7. Root of permanent tooth is the last thing to develop as the tooth comes into occlusion

What is the general pattern of eruption for deciduous and permanent teeth?

Teeth generally emerge front to back

-Exception: 1st permanent molar is the first adult tooth to erupt

What signifies mixed dentition?

The eruption of the 1st permanent molar

What is the purpose of developmental spacing?

Adult teeth are much larger, so the baby teeth are spread out in order to account for the space needed for adult teeth

What are the 6 traits of all deciduous teeth?

- Smaller in size than analogous teeth

- Whiter in color

- Constricted at cervix, causes a more bulbous appearance

-Thinner enamel and dentin with larger pulp chambers (aids in tooth decay)

-Less mineralized (higher attrition- wearing down of tooth)

-More consistent, fewer anomalies

Which comes first, the crown or the root?

Crown

In utero anterior teeth, what is the order of development?

1. Deciduous central incisors

2. Deciduous lateral incisors

3. Deciduous canines

In utero posterior teeth, what is the order of development?

1. Deciduous 1st molars

2. Deciduous 2nd molars

3. Permanent 1st molar also forming during this time

How many teeth will be erupted at birth?

Generally none, however, if the pregnancy lasts longer than the gestation period, the baby may come out with teeth in occlusion

What is the order of development for postnatal teeth?

1. Permanent incisors

2. Permanent canines

3. Permeant premolars + 2nd molar

What are some factors affecting the timing of dental development?

- Gender

- Ancestry

-Generational (modern vs ancient)

Which gender's teeth develop earlier?

Females

Who's was the first aging method and when?

Moorrees 1963

What did Moorrees' aging method show?

It showed 14 developmental stages by taking x-rays at 6 month intervals

Who's aging method was responsible for the first range of tooth growth and when was it developed?

Gustafson and Koch 1974

What did Gustafson and Koch do to form their aging method?

Combined multiple studies

Which aging method is the most widely used?

Ubelaker Chart

What is the issue with the Ubelaker Chart?

It was made using the teeth of prehistoric Native Americans

Which aging method is the most up-to-date and accurate and why?

AlQantani because it was developed using the teeth of modern children

Why would you use a slow speed saw to make histology slides of teeth?

Histology focuses on the cells/microstructures of teeth; microstructures are very fragile so in order to not shatter the tiny cells of the tooth, a slow speed saw is necessary

Micrograph

Picture taken under a microscope

-series of photos pieced together to form entire image

What are different ways to see aging within microstructures?

- Cementum layers

-Resorption of root

-Secondary dentin

How can cementum layers show age?

Over time, cementum accumulates at apex of the root

How can root sclerosis show age?

as you age, dentin in the root is filled in; observe how much dentin is filled in

-proportion: different for each person (1/3 of root)

-infiltration: measured amount (1 cm)

How can secondary dentin show age?

Ratio to see if we see a proportional change (primary dentin, secondary dentin, pulp chamber)

-There is a low correlation with age, more correlation with genetics

Point cloud

A collection of points that follow along the surface of an object

What are the 4 benefits of 3D scanning?

-Non-destructive

-Non-invasive

-Easily manipulated

-Easy to have data management

What are the harms of 3D scanning?

-Takes a long time to do

-High file sizes

-Need for special equipment which can be expensive

-Ethics

What is the best way to scan an object?

MicroCT

How does MicroCT operate?

It produces a 3D image of the inside and outside of an object by taking a series of 2D x-rays (slices of x-rays through the object)

What can a MicroCT image show us?

-Volumetric representations of features like enamel, dentin, and pulp chamber

-Conversion to surface data

What is the cheapest method of 3D Modeling?

Photogrammetry

Photogrammetry

Measurements from a series of photos taken all around an object

What are the problems with photogrammetry?

Cannot be used for precise measurements and it is not very accurate