Anthropology ortho

Anthropology and orthodontics

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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

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Contents     

Introduction Anthropology-basics Classification of human groups Classification of mammals Dental features of primate apes humans

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Anthropologic studies Anthropometry

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Why anthropology? 

Orthodontists are functioning anthropologists.

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We measure the bones of the face skull and teeth and study the relationship of these structures.

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Thus we should be interested in learning about the origins of human beings and evolutionary development of our anatomy. www.indiandentalacademy.com

What is anthropology? 

The word anthropology derives from the Greek anthropos, meaning "man," and logos, meaning "study.“

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Therefore, anthropology is the study of people. It is the study of humans in all places and at all times

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It is a search, an investigation into what we are now, from where we came and how we got to be the way we are today. www.indiandentalacademy.com

Branches of anthropology 

There are four main branches in the study of people:

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Sociocultural anthropology Archaeology Linguistics Physical anthropology

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Applied anthropology www.indiandentalacademy.com

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Sociocultural anthropology -understand human social organization and culture.

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Archaeology- study material remains of human activity in order to reconstruct how different cultures adjust to varying situations through time and to explain stability and change.

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Anthropological linguist- examines the history, function, structure, and physiology of one of a people‘s most definitive characteristics- language.

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Applied anthropology - concerned with the application of anthropological ideas to current human problems.

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Physical anthropology- studies the biological nature and evolution of humankind.

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Physical anthropology focuses on the place of man in nature.

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It is a search into the ancestry, development, genetic, and other characteristics of the human species.

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Paleontology -The study of fossils.

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Paleoanthropology- the study of the fossils of modern humans and human ancestors.

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Anthropometry -systematic art of measuring and taking observations on man, his skeleton, his brain, or other organs, by the most reliable means and methods for scientific purposes.

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Primatology www.indiandentalacademy.com

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Forensic anthropology –It is a specialized area of physical anthropology.

It is the identification of human remains for legal purposes.

Teeth are especially important for several reasons.

Dental records are common Contain many details Can endure more harsh conditions

Dental anthropology - It is the study of teeth as recorded in casts of living mouths or as seen in the www.indiandentalacademy.com skulls of archaeological and fossil collections.

Some Characteristics of Humankind 

Physical anthropologists study the characteristics that define us as human.

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THE DEPENDENCE ON CULTURE

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Culture is learned, nonrandom, systematic behavior and knowledge that is transmitted from person to person and from generation to generation. Culture changes through time and is a main contributor to human adaptability. www.indiandentalacademy.com

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THE HUMAN BRAIN AND ITS ABILITY TO SYMBOLIZE

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One thing that makes the human brain a revolutionary instrument is the potential for speech.

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A symbol is anything, whether it be visual, oral, tactile, or olfactory, that represents something else that is distant in time and space.

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BIPEDALISM

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The ability to walk consistently on two legs, is a human trait.

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Although human anatomy is adapted for bipedal locomotion, the neural control needed to walk bipedaly is learned behavior.

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Myths about Humankind 

THE MYTHS ABOUT HUMAN ANTIQUITY- humans developed last

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THE MYTH OF TECHNOLOGY- some things are biologically impossible ,similarly others are technologically infeasible or improbable. It is not likely that we will solve the world's food problem through technology.

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If technological "progress" is not accompanied by appropriate social change and ecological responsibility, people may drown in the poisons of their own industrial wastes.

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cannot continue to grow in

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THE MYTH OF PLENTY-

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number limited number of plants lack of space

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THE MYTH OF HUMAN SUPERIORITY-

Anthropocentricity

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THE CLASSIFICATION OF HUMAN GROUPS 

Folk taxonomies These categories reflect specific cultural traditions and differ from society to society.

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Folk Taxonomies of Race

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Greeks and barbarians Caucasoids, Mongoloids, Negroids, whites , African Americans, Indians and Asians etc.

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Do they reflect reality?

YES and NO

Many forms of behavior are determined by them.

But no anthropologically. www.indiandentalacademy.com

Scientific Classification 

Carolus Linnaeus- skin color, geographical location, and personality traits.

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H. H. H. H.

sapiens sapiens sapiens sapiens

Africanus negreus (black) Americanus rubescens (red) Asiaticus fucus (darkish) Europeus albescens (white).

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Various criteria used for classification-

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Skin colour Blood group Fossil record Geographic distribution

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New classification- J. Friedrich Blumenbach

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Caucasian Mongolian Ethiopian Malayan American.

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Garn's classification based on geographical distribution

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Amerindian (the aboriginal inhabitants of North and South America) Asiatic Australian Melanesian (peoples of New Guinea and neighboring islands) Micronesian (peoples of the islands of the northwest Pacific) Polynesian Indian (peoples of the subcontinent of India) African European.

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Humans place in living order

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CLASSIFICATION OF THE MAMMALS ď Ž

Mammals belong to the class Mammalia, which is divided into two subclasses containing three groups that correspond to the three major kinds of mammals.

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Prototherian mammals (monotremes) Platypus and the Echidna Lay eggs also produce milk.

They possess both reptilian and mammalian characteristics.

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Therian mammals

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They produce live young.

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Can be divided into two infraclasses.

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Metatheria – marsupials (pouched mammals) Metatherian offspring are born while they are still fetuses.

The fetus then crawls into the mother's, pouch or fold, where it continues to develop and mature. www.indiandentalacademy.com

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Eutheria- These are the placental mammals

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Their young remain inside the mother, nourished by the placenta, until they reach an advanced state of development.

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The primate order   

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Every order has a characteristic feature like: Chiroptera ie. the bats have wings Carnivora have sharp teeth

So, what is special about primates?

Adaptability This is a response to arboreal habitat.

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Features of primates 

Shared retained features-

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Presence of clavicle.

Presence of radius and ulna Pentadactylism

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Shared derived features.

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Arboreal.

Replacement of claws by nails.

Ability to grasp- great toe and opposable thumb Sense of touch- tactile pads.

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Poor sense of smell Highly advanced vision-binocular, stereoscopic and coloured.

More intelligent Social Produce single births.

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THE ORIGIN OF JAWS 

A major event in Vertebrate evolution was the evolution of jaws.

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New structures do not simply arise from nothing.

They develop as modifications of preexisting structures.

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The jawless vertebrates have skeletal elements, gill bars, that support the gill slits.

In early fish, the first gill bars enlarged to become primitive jaw. www.indiandentalacademy.com

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Filter feeding restricted the jawless vertebrates to very small food particles.

The evolution of jaws enabled them to prey on one another and to proliferate.

Today these jawed vertebrates are represented by the sharks and bony fish.

Land vertebrates eventually evolved from a population of freshwater bony fish.

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WHAT IS DENTAL ANTHROPOLOGY? 

Dental Anthropology is the study of teeth in a perspective beyond clinical science.

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That perspective includes the study of dental growth, theories on dental origin, primate dentition, and population variation.

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The first comprehensive review of research on primate dentition was by Krogman in 1927. www.indiandentalacademy.com

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What do dental anthropologists do?

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(1) Genetically controlled variables such as tooth crown size and morphology are used to trace phylogenetic relationships and historic trends in size, shape, and number of teeth.

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(2) Crown wear and dental pathology give clues to dietary and cultural behavior.

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(3) Gross and microscopic defect analyses reflect disease and dietary stress.

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(4) Intentional cultural modifications of teeth reflect society and culture of people, both present and past. www.indiandentalacademy.com

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(5) Bite marks, distinctive patterns of occlusion and wear, missing and filled teeth, and radiographic landmarks make teeth pivotal in many cases of forensic identification.

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(6) The comparative anatomy of teeth provides crucial evidence for systematics (classification) and determining biological relatedness.

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Terminology in dental anthropology     

Homodont Heterodont Monophyodont Diphyodont Polyphyodont

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Crown Form 

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Bunodont (Gr = mound or hill) teeth have coneshaped tubercles or cones; they are low crowned with well-developed roots. example is the posterior teeth in the pig.

Selenodont (Gr = the moon) teeth have cusps transformed into half-moon shapes.

The concave side faces laterally in the upper jaw; lingually in the lower jaw. example is in the cheek teeth of sheep. www.indiandentalacademy.com

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Sectorial (L = secare to cut) teeth are blade-like teeth adapted to cutting the diet into pieces and swallowing them whole.

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Lophodont (Gr = crest) molars are ridged teeth that have transverse ridges as in the tapir.

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Bilophodont molars have two sets of transverse ridges.

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Polylophodont molars have many ridges as seen in the elephant molar www.indiandentalacademy.com

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Brachydont (Gr = short) teeth have low crowns and welldeveloped roots. This condition is seen in humans

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Hypsodont (Gr = height) teeth have long crowns and short roots as seen in the horse. In them, it is a functional adaptation for continuous wear sustained by chewing grass with a high abrasive silica content.

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Tusks are incisors or canines of continuous growth that protrude beyond the lips when the mouth is closed.

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Primate dentition 

Mammals are characterised by-

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Heterodont Diphyodont

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Primate teeth Four kind of teethIncisors Canines Premolars molars www.indiandentalacademy.com

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The Incisors are broad, cutting type of tooth with a simple structure Described as spatulate The incisors are used to grasp food.

Primates that eat fruit use their incisors to tear small pieces Smaller food objects, such as seeds and grass are usually passed directly back to the cheek teeth.

Primates that specialize in this type of diet often have smaller incisors than do the fruit eaters. www.indiandentalacademy.com

Dental comb •

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Prosimians are characterized by the development of a dental comb which is formed by lower incisors and canines that project forward horizontally The lower canine is included in the comb.

The functions of the canine are taken over by the first premolar, which then become canine like in appearance.

The animal uses comb for grooming the fur and for scraping gum and resins off the bark of trees. www.indiandentalacademy.com

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Canine- pointed ,curved usually larger than other teeth Function- grasping, stabbing, ripping and tearing food Plays a role in defense.

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Premolars and molars-

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Called as cheek teeth Function-chewing

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DENTAL FORMULAS 

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The types and numbers of teeth are designated in dental formulas.

Dental formula of the common ancestor of living placental mammals is 3.1.4.3 3.1.4.3 Primate evolution is characterized by a loss of teeth in the dental formula. www.indiandentalacademy.com

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APE DENTITION 

The incisors of the great apes are quite broad and spatula-like

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Upper incisors are implanted at an angle

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Canine is large and projecting.

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Spaces present in relation to canine ie primate spaces.

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When the animal closes its mouth, the canines interlock, each fitting into a space, or diastema in the opposite jaw.

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In the upper jaw the diastema is in front of the canine, while in the lower jaw it is behind the canine.

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Sexual dimorphism is present

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Arches are ‘U’ shaped.

Sectorial premolar.

Upper molar has 4 cusps and lower has 5 cusps called as Y-5 pattern

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Hominid dentition 

Size of teeth is decreased

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Arch length is reduced

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All teeth are at same level

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Canine is not projecting

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Premolar is not sectorial

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No diastema

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Curved or parabolic arch

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Incisors are narrower and are vertical

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Not much of sexual dimorphism

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Molars have more rounded cusps

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Thick enamel-more crushing due to tough and hard diet www.indiandentalacademy.com

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The jaw 

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The human jaw is smaller and is shorter relative to the skull than is the ape jaw.

This is because human food is processed, so no need to exert much pressure.

Apes have a simian shelf which is absent in humans-a reinforcement or buttressing.

A prominent chin is a feature of humans

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Size of muscles of mastication is smaller.

Apes have large jaw & teeth and a large masseter.

Thus, have a robust zygomatic.

A large temporalis is associated with flaring zygomatic arch.

In humans this is slender and non flaring

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ULTRASTRUCTURE OF TOOTH ENAMEL 

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Electron microscope studies have shown that the structure of tooth enamel is very regular, yet variations exist among species.

There are three major patterns in the arrangement of prisms.

Distinct differences in pattern exist between living hominids and living and fossil anthropoids. www.indiandentalacademy.com

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Pattern 1 prisms are found in insectivores and many bats.

Pattern 2 prisms are found in most hoofed mammals, rodents, and marsupials.

Prisms with pattern 3, often called the "keyhole" pattern, are commonly found in humans.

All three enamel types can be found in the primate order.

Pattern 3 is found in human enamel Pattern 2 is frequently found in the enamel of the rhesus monkey Pattern 1 in the lemurs. www.indiandentalacademy.com

DENTITION AND DIET 

Primates have 3 dietary adaptations

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Insectivores (insect eating) Frugivores(fruit eaters) Folivores(leaf eaters)

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Special dental adaptations to special dietary requirements.

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Molars of folivores are characterized by development of shearing crest

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Insectivores molars have high pointed cusps to puncture the outer skeleton of insects.

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Frugivores have molars with rounded cusps, few crests. www.indiandentalacademy.com

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Development of Hominoids    

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Comprise of apes and humans.

First hominoids belong to early miocene era.

Were called as ‘dental apes’ .

Because dentition resembles that of modern apes.

Fossils were discovered in 1930’s in africa.

Important genus is ‘proconsul’. www.indiandentalacademy.com

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Features

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Vertically implanted incisors Slender canines Thin enamel on molars V shaped dental arch.

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There was migration of various species to Eurasia from Africa.

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Jay Gould- said that the correct image for the visualization of evolution is that of a "copious branching bush" not that of a tree or ladder.

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Miocene hominoids Dryomorphs–Africa, Europe eg: procunsul  Ramamorphs-eastern Europe, India ,Pakistan eg:shivapithecus  Pliomorphs 

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Features of Ramamorphs Thick enamel on molars Low cusps Small canines Sexual dimoprhism Broad central incisors Orthognathous mandible

Suggesting coarse diet www.indiandentalacademy.com

The skull of Sivapithecus. www.indiandentalacademy.com

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Gigantopithacus – it was probably the largest ape that ever lived.

It may have been as tall as 2.75m and may have weighed as much as 272 kg.

Found in India ,Pakistan and China FeaturesSmall vertically implanted incisors Reduced canines worn flat by the chewing of coarse vegetation Lack of a diastema Crowding of the molars & premolars

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What did gigantopithecus have for dinner?      

Paleoanthropology includes the reconstruction of information about the life of extinct forms.

Eg:diet Recent advances in this field are the identification of phytoliths.

These are plant specific minerals which are preserved during fossilisation.

Pieces of silica; visible under SEM. Giganthopithecus diet include grasses like bamboo and fruits. www.indiandentalacademy.com

Australopithecus   

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Belong to family Hominidae The other genus is Homo Considered to be the earliest forms in the direct line leading to modern humans.

Fossils found mostly in Africa They extinct 900,000 million years ago

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Australopithecine Dentition 

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Australopithecine dentition is very hominid-like.

A greater degree of sexual dimorphism.

Resembles apes in some features and simultaneously is different in many ways.

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Features Posterior teeth lie in a fairly straight line except for the third molar which is positioned inward.

The upper incisors are relatively large and project forward.

The canines project above the tooth row and are conical in shape, in contrast to the spatulate shape of the modern human canine.

Arch size is intermediate b/w modern humans and apes They have shallow palate. www.indiandentalacademy.com

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Ethiopia www.indiandentalacademy.com

Genus Homo     

Classification Consist of 3 species Homo habilis ( handy human being) Homo erectus (erect human being) Homo sapiens (wise human being)-the only living member of the genus

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H.habilis

Had large jaw and teeth Although molars and premolars decreased in size.

Face was broad and flat

H.erectus Were found in Java and china Shows reduction in jaw size More similar to Homo sapiens Arches diverge posteriorly More emphasis on incisors and canine Suggesting meat in diet Mandible lacks a chin Have a mandible torus www.indiandentalacademy.com

H sapiens ď Ž ď Ž

Found in Africa,Asia &Europe.

Had dental caries and abscess in the jaw

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Neandertals ď Ž

Some believe they are the direct ancestors of modern humans belonging to species H.sapiens

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Others believe them to be a separate species which was highly advanced in themselves Neandertals

Modern humans

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Features Enlarged facial sinus 2. Forward projecting face 3. Teeth project forward 4. Gap b/w last molar and ramus 5. Varying development of chin 6. Arthritis in TMJ-excess stress may be they were using teeth as tools 7. Incisors larger than modern humans 8. Molars and premolars are similar 9. Third molars were small sometimes 10. Showed high wear of teeth 1.

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Homo sapiens sapiens ď Ž ď Ž

Believed to be originally from Africa 130000 years ago to present date

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Anthropologic studies 

Blandin made the first attempt to describe facial growth (1836), finding that the pterygoid process backs up to the posterior aspect of the maxilla

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T. Wingate Todd (1885-1938) an English physician and anatomist, made his great contributions by undertaking growth studies.

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He established standards of normal growth and development at any period of childhood.

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Using comparative anatomy and paleontology, Milo Hellman in 1927 demonstrated posterior growth of the face by surface additions to the maxillary tuberosities as the face swings out from beneath the cranium during growth. www.indiandentalacademy.com

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The 1920s saw a final burst of anthropologic studies

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In 1922, Keith and Campion, by superimposing drawings of skulls of different ages, found that the face grows mostly forward, a bit upward, and considerably downward, whereas mandibular growth is up and back.

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In 1924, Brash published The Growth of the Jaws and Palate, in which he stated that, when he injected a red dye (madder) into a pig’s skull, he found a delicate balance between deposition and resorption, depending on the functional demands made on it.

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1929, William K. Gregory (1876-1970) published From Fish to Man, describing changes traced through 10 successive stages of phylogenetic development of the human face.

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Wilton M. Krogman contributed an anthropologic comparison between the growth patterns of the anthropoid and the human head.

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Impacted canine in a prehistoric skull   

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Angle orthodontist 1996 Skull was found in 1984 in Vukovar,Croatia Specimen was of a female subject 35 to 45 years old Age of the specimen was 2700 to 2400BC In the maxilla left canine was impacted.

Similar reports have been published by Iseri and Uzel &Sullivan and Hellman

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Normally hypodontia and impacted teeth are considered evolutionary alterations

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But impaction also occurred in prehistoric man

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Therfore it implies that the abnormality in eruption of teeth is not caused by modified conditions brought about by modern civilization

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Takashii Kaji did a study on Japanese population to evaluate the presence of 3rd molar germs (AJO 2001)

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ANTHROPOLOGY AND MALOCCLUSION 

In the 1930s, Weston Price travelled the world to document the nutritional habits and physical degeneration of people living on contemporary 'civilized' diets.

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He found a significant increase in malocclusion in societies living on contemporary diets of prepared foods from domesticated crops.

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Malocclusion arises from the lack of chewing stress with the modern processed diet. This disuse has reduced jaw growth and increased the incidence of occlusal variation.

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Numerous studies are documented by Corrucinni (1991) which confirm and extend the findings by Price www.indiandentalacademy.com

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COMPARISON IN AN ISOLATED RURAL COMMUNITY IN TRANSITION

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A rural community in the Mammoth Cave region of central Kentucky was surveyed over a 25 year period as it made the transition to industry and mechanized farming.

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The diet at the outset was home-produced foods (especially dried pork and fried cornbread) which provided consistently stressful chewing.

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The transition was from this to a diet of purchased supermarket foods. This study was of special interest since diet changed but residence did not.

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Arch breadth was smaller and significantly more variable in younger individuals.

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Bigonial breadth, measured from an area affected by the medial pterygoid and masseter muscle action was considerably smaller in the younger sample.

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This study tends to suggest that there is a genetic predisposition or susceptibility to be diverted from programmed oral growth pathway by environmental factors.

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Lack of function, therefore, led to a different phenotypic expression--one with more occlusal variation.

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OCCLUSAL VARIATION IN NORTHWEST INDIA Children of similar genetic heritage, but differing lifestyles have been studied side-by-side in India.

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The communities studied included children born into a higher socioeconomic urban class and children from rural communities with its traditional dietary and residence habits.

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Significant differences were found in the samples. The lowest socioeconomic group had less variation from ideal occlusal relations and had wider (broader) maxillary arches.

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Lack of functional stimulation could explain occlusal changes that were observed: small jaws with normal-size teeth, resulting in crowding plus maxillary narrowing. www.indiandentalacademy.com

THE BEGG HYPOTHESIS AND THE EPIDEMIOLOGY OF MALOCCLUSION 

Dr.P. R. Begg has studied both living and deceased Australian Aborigines and has used them as a model for Stone Age man.

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He wrote his doctoral thesis “the evolutionary reduction & degeneration of man’s jaws & teeth” in 1939.

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In 1954 he published paper entitled “Stone age man’s dentition

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In 1954, Begg reasoned that the relatively low incidence of malocclusion in Stone Age Man is due to the reduction by more than half an inch in the total length of each of his dental arches.

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This was caused by tooth attrition so that the smaller crowns could be more easily accommodated into the jaws

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Begg also argued that retention of unworn occlusal-cusp was not a feature of non-modern societies www.indiandentalacademy.com

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According to him the function of cusps is transitory: they establish mandibular and condylar position.

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A flat plane occlusion allows protrusive and lateral movments without cuspal interferences and is therefore less susceptible to TMJ disturbances

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THE ETIOLOGY OF THIRD MOLAR IMPACTIONS 

Humans evolved in a high dental attrition environment

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Combined with physiological mesial drift, humans would effectively achieve an increasing retromolar space as they age.

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The delayed eruption of the third molar seems to be an evolutionary adaptation to interproximal wear of the cheek teeth.

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The recent secular trend in increasing impactions does not seem to be a genetic change in humans. It is, instead, merely a response to a soft food diet. Without interproximal wear of the teeth, there simply is not enough room for third molar www.indiandentalacademy.com

DENTAL CARIES 

The clearest single factor in caries epidemiology is sugar.

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This is demonstrated by the decrease in the rate of caries during sugar rationing in Japan, Norway, and the Island of Jersey during World War II.

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Dental caries also occurs amongst the great apes. particularly the chimpanzees.

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Of the great apes, chimpanzees have a diet most similar to our own; in the wild their diet includes a lot of fruit in addition to leaves, flowers, nuts, termites.

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Gorillas, which are primarily leaf eaters, have a much lower rate of dental caries. The orangutan in intermediate between chimpanzees and gorillas.

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In the most ancient hominids, the incidence of caries is less than 1%.

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TOOTH AGENESIS ď Ž

Agenesis of one or more teeth is one of the most common of human developmental anomalies

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Agenesis and polygenesis has been reported for the apes and Old World monkeys. The frequency of agenesis amongst the hominoids is highest in humans and is found most frequently in the molar region.

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ANTHROPOMETRICS IN ORTHODONTICS 

The quantification of man is a function of modern biology.

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Anthropometry+ craniometry =cephalometry

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ANTHROPOMETRIC AND CEPHALOMETRIC PROCEDURES   

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INSTRUMENTS Measuring tape- Flexible steel tape graduated in millimeters.

Anthropometer- Hollow sliding rods, graduated in millimeters, used for taking various measurements including vertical and transverse body measurements.

Sliding Calipers -This is employed to measure head and face diameters.

Sliding Compass- To measure smaller diameters of the head.

Head Spanner- To determine height of the head. www.indiandentalacademy.com

Various measurements 

Head Length- The maximum glabella occipital diameter

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Is obtained with the spreading calipers.

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This dimension is taken from the most prominent point on the glabella to a point on the vertical line bisecting the occiput

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Head breadth - is the greatest transverse diameter measured in the horizontal plane above the supramastoids and the zygomatic crests.

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This measurement is taken with the spreading calipers.

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Head circumference - is taken with a steel tape through the most prominent part of the occiput and just above the supra-orbital ridges.

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Head Height -

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Facial Height- (Sliding calipers).

Total facial height -nasion (N) to Gnathion (Gn) Upper facial height -nasion (N) to Prosthion (Pr) Dental height -from prosthion to infradentale.

Lower facial height - infradentale to gnathion (Gn).

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Facial Width –

Bizygomatic -zygion to zygion Bigonial - gonion to gonion.

Maximum Mouth Breadth - The maximum breadth of the mouth when the face is in a relaxed condition (from cheilion to cheilion). www.indiandentalacademy.com

CRANIOFACIAL INDEXES ď Ž

Definition- An index in anthropometry is the ratio of a smaller to a larger measurement taken as equivalent to 100 and expressed in terms of a percentage.

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To determine the proportional relation of the breadth (width) of the head to its length (depth), it is equated to the value of 100, and the breadth then is expressed as a ratio of 100.

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Cephalic index is grouped under three categories defined by Martin as follows:

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Dolichocephaly Mesocephaly Brachycephaly

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75.9 76.0 - 80.9 81.0

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The cephalic index at the 4th month of intrauterine life is very high, since until this time width grows faster than length.

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After this period the ratio falls rapidly, The cephalic index decreases before birth and the head is relatively dolichocephalic (anteroposteriorly longheaded). www.indiandentalacademy.com

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The facial index- it is the ratio of the length of the face to the width

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The index of the upper face to the lower face may be obtained in the same manner.

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The index increases slightly annually as the child grows; the face becomes relatively broader www.indiandentalacademy.com

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The palatal index -is the ratio of the breadth to the length

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Breadth of the palate is taken from the mesial pits of the right and the left first molars.

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Length is taken from the inner alveolar point between the maxillary central incisors to the posterior nasal spine as seen on the roentgenogram or dry skull. www.indiandentalacademy.com

Conclusion ď Ž

Anthropology not only provides an insight into the human evolution but also gives us a better understanding of the development of malocclusion and the probable etiology behind it.

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