Why study Diet? Utility for model building? Food provides energy necessary to sustain life and allow for reproduction Main activity of most animals’ lives Major component of natural selection: “obtain food and keep from becoming food”

Why study teeth? Utility for model building? Indicate foods consumed Indicate size & behavior Well preserved in the fossil record Growth & development patterns Sexual dimorphism characteristics Non-dietary indicators

Tooth Types

Human Dentition Tooth Types

Roles of the teeth Differential 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 Extinct Data collection from the living primates

Diagnostic features Incisors & canines Features of the skull used to determine dietary category Molars & premolars Cusps & crests Enamel thickness Massiter & temporalis muscles Body size

Anterior Dentition Get food in the mouth Grooming Scraping ~~~~~~~~~~~~~~~~~~~~ Get food in the mouth Grooming Scraping ~~~~~~~~~~~~~~~~~~~~ Incisors & Canines Large incisors indicate frugivore Small incisors = carnivore or insectivore Large incisors indicate frugivore Small incisors = carnivore or insectivore

Incisors

Canines

Premolars & Molars Posterior Dentition Folivores = low or high Insectivores = tall, pointed Carnivores = tall, pointed Frugivores = low, rounded Omnivore = low, rounded

Premolars & Molars

Cusps & Crests Molar & premolar morphology cusp crest

Enamel thickness Thickness of the hard mineral surface covering the teeth

Dental Attrition Enamel wear

Muscles of mastication

Body size Diet dictates primate body size Body-size tends to correlate w/ dietary regime Body-size tends to correlate w/ dietary regime Folivore = largest Insectivore = smallest Frugivore = medium to large

Dietary strategies Folivore - plants Categories of Diet for the Primates Frugivore - fruit Carnivore - meat Insectivore - insects Omnivore - mixed

Age Changes Subadult Dentition

Human Chewing Anatomy of the TMJ temporalis massiter 1. Temporal bone 2. Mandibular condyle

Human Chewing Movement 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 Chewing Motions of the Mandible …but subject to very complex movements and forces.

Human Chewing “Disarticulation” of the TMJ

Human Chewing Nerves & Blood Vessels around TMJ

Human Chewing Disorders of the TMJ & Associated Structures Developmental Condylar Hyperplasia Hyperplasia Agensis Infectious Spread Tuberculosis Syphillis Gonorrhea Staphylococcal Infection Streptococcal Infection Inflammatory rheumatoid arthritis Psoriatic arthritis Reiter’s syndrome Systemic lupus erthematosis Familial Mediterranean fever Degenerative osteoporosis Traumatic Condylar Fracture Ankylosis Internal rearrangement Metabolic Gout Pseudogout TMJ Pain Dysfunction Neoplastic Benign Tumors Fibro-Osseous Disorders Fibrous dysplasia Paget’s disease Luxation & Subluxation

Human Chewing Clinical Aspects Burt Reynolds “In” malady drew attention to the extent of the disorder

Human Chewing Treatments

Human Chewing Measuring Mandibular Angle

Human Chewing Molar & Incisal Chewing

Human Chewing Hylander’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 Chewing Categories Studied Age Sex Complete Socket Resorption Active Pathologies Dental Attrition Age Sex Complete Socket Resorption Active Pathologies Dental Attrition

Human Chewing Age Changes in the Mandible Lateral View Dorsal View

Human Chewing Age & Sex Relationships AGE SEX male female TMJ PATHOLOGY

Human Chewing Complete Socket Resorption

Human Chewing Complete Socket Resorption

caries partial socket resorption abcess

Human Chewing Dental Caries & Abcesses 0.79 ABCESS CARIES TMJ PATHOLOGY PARTIAL RESORPTION

Human Chewing Dental Attrition tooth wear

Human Chewing Results Significantly more females affected compared to males Greater wear found on the same side as TMJ damage Greater wear found on side opposite carious lesions Trends similar to clinical findings