Why study Diet?Why study Diet?Utility for model building?

Food provides energy necessary to sustain life and allow for reproduction

Food provides energy necessary to sustain life and allow for reproduction

Main activity of most animals’ livesMain activity of most animals’ lives

Major component of natural selection: “obtain food and keep from becoming food”

Major component of natural selection: “obtain food and keep from becoming food”

Why study teeth?Why study teeth?Utility for model building?

Indicate foods consumed Indicate foods consumed

Indicate size & behavior Indicate size & behaviorWell preserved in the fossil recordWell preserved in the fossil record

Growth & development patternsGrowth & development patternsSexual dimorphism characteristicsSexual dimorphism characteristicsNon-dietary indicatorsNon-dietary indicators

Tooth

Typ

es

Tooth

Typ

es

Human Dentition

Tooth TypesTooth Types

Roles of the teethRoles of the teethDifferential use in heterodont dentition

Incisors & canines -- ingestion, get the food into the mouth seizing, stripping, squashing, puncturing

Incisors & canines -- ingestion, get the food into the mouth seizing, stripping, squashing, puncturing

Premolars & molars -- preparation of food for digestion food is chopped up to increase surface area molars are a series of cutting blades and crushing

basin

Premolars & molars -- preparation of food for digestion food is chopped up to increase surface area molars are a series of cutting blades and crushing

basin

Extant vs ExtinctExtant vs ExtinctData collection from the living primates

Diagnostic featuresDiagnostic features

Incisors & canines Incisors & canines

Features of the skull used to determine dietary category

Molars & premolarsMolars & premolars

Cusps & crestsCusps & crestsEnamel thicknessEnamel thicknessMassiter & temporalis musclesMassiter & temporalis musclesBody sizeBody size

Anterior Dentition

• Get food in the mouth• Grooming• Scraping~~~~~~~~~~~~~~~~~~~~

• Get food in the mouth• Grooming• Scraping~~~~~~~~~~~~~~~~~~~~

Incisors & CaninesIncisors & Canines

• Large incisors indicate frugivore

• Small incisors = carnivore or insectivore

• Large incisors indicate frugivore

• Small incisors = carnivore or insectivore

Incisors

Can

ine

s

Premolars & MolarsPremolars & MolarsPosterior Dentition

•Folivores = low or high•Folivores = low or high

•Insectivores = tall, pointed

•Insectivores = tall, pointed

•Carnivores = tall, pointed•Carnivores = tall, pointed

•Frugivores = low, rounded

•Frugivores = low, rounded

•Omnivore = low, rounded•Omnivore = low, rounded

Premolars& MolarsPremolars& Molars

Premolars & MolarsPremolars & Molars

Premolars & MolarsPremolars & Molars

Cusps & CrestsCusps & CrestsMolar & premolar morphology

cusp

crest

Enamel thicknessEnamel thicknessThickness of the hard mineral surface covering the teeth

Dental AttritionDental AttritionEnamel wear

Muscles of masticationMuscles of mastication

Body sizeBody sizeDiet dictates primate body size

• Body-size tends to correlate w/ dietary regime

• Body-size tends to correlate w/ dietary regime

• Folivore = largest• Folivore = largest

• Insectivore = smallest• Insectivore = smallest

• Frugivore = medium to large

• Frugivore = medium to large

Dietary strategiesDietary strategies

Folivore - plants Folivore - plants

Categories of Diet for the Primates

Frugivore - fruit Frugivore - fruit Carnivore - meat Carnivore - meat Insectivore - insects Insectivore - insects Omnivore - mixed Omnivore - mixed

Age ChangesSubadult Dentition

Human ChewingAnatomy of the TMJ

temporalis

massiter

1. Temporal bone2. Mandibular condyle

Human ChewingMovement of the TMJ

• held in place by a sheath of tendon and muscles

• glides on cartilage

• Bursa helps absorb some forces

• Literal double joint

• held in place by a sheath of tendon and muscles

• glides on cartilage

• Bursa helps absorb some forces

• Literal double joint

Human ChewingMotions of the Mandible

…but subject to very complex movements and forces.

…but subject to very complex movements and forces.

Human Chewing“Disarticulation” of the TMJ

Human ChewingNerves & Blood Vessels around TMJ

Human ChewingDisorders of the TMJ & Associated Structures

DevelopmentalCondylar HyperplasiaHyperplasiaAgensis

Infectious SpreadTuberculosisSyphillisGonorrheaStaphylococcal InfectionStreptococcal Infection

Inflammatoryrheumatoid arthritisPsoriatic arthritisReiter’s syndromeSystemic lupus erthematosisFamilial Mediterranean fever

Degenerativeosteoporosis

TraumaticCondylar FractureAnkylosisInternal rearrangement

MetabolicGoutPseudogout

TMJ Pain Dysfunction

NeoplasticBenignTumors

Fibro-Osseous DisordersFibrous dysplasiaPaget’s disease

Luxation & Subluxation

Human ChewingClinical Aspects

• Burt Reynolds• Burt Reynolds

• “In” malady• “In” malady

• drew attention to the extent of the disorder

• drew attention to the extent of the disorder

Human ChewingTreatments

Human ChewingMeasuring Mandibular Angle

Human ChewingMolar & Incisal Chewing

Human ChewingHylander’s Lever Action Model

• Trouble w/TMJ:Chew on the same side as pain

• Trouble w/TMJ:Chew on the same side as pain

• Trouble w/molar:Chew on the opposite side

• Trouble w/molar:Chew on the opposite side

The Nubians

Human Chewing

condyle pathology

fossa pathologies

Human ChewingCategories Studied

Age Sex Complete Socket Resorption Active Pathologies Dental Attrition

Age Sex Complete Socket Resorption Active Pathologies Dental Attrition

Human ChewingAge Changes in the Mandible

Lateral ViewLateral View

Dorsal ViewDorsal View

Human ChewingAge & Sex Relationships

35.12AGE

SEXmalefemale

TMJ PATHOLOGY- +

34.47

26.40

70.60

47.60

52.40

Human ChewingComplete Socket Resorption

Human ChewingComplete Socket Resorption

0

2

4

6

8

10

12

+ -TMJ Pathology

caries

partial socket resorption

abcess

Human ChewingDental Caries & Abcesses

0.79ABCESSCARIES

TMJ PATHOLOGY+ -

0.24

0.71

2.88

1.39

2.27PARTIALRESORPTION

Human ChewingDental Attrition

tooth wear

Human ChewingResults

• Significantly more females affected compared to males

• Significantly more females affected compared to males

• Greater wear found on the same side as TMJ damage

• Greater wear found on the same side as TMJ damage

• Greater wear found on side opposite carious lesions

• Greater wear found on side opposite carious lesions

• Trends similar to clinical findings• Trends similar to clinical findings