Dental Anthropology Exam #1

chimp v human dental development chronology

-M1 in humans before I1 in chimps -delayed emergence of canine in chimps -overlap in molar crown formation times -differences in emergence ages

dentinogensis

3 types: (formed by odontoblasts, stay after formation) -primary -secondary -tertiary

Tribosphenic molar

A molar characterized by the presence of three main cusps, a variable number of accessory cusps, and crests with sharp edges. It first appears in therian mammals (the ancestors of extant marsupials and placentals)

Diastema

A space between two teeth

enamel prisms

Another term for enamel rods that make up the enamel structure

H.F Osborne Tritubercular Theory

Basic reptilian tooth: single main cusp ("proto" cone) Early Mammal (Tertiary): developed triangle elements with some modification Conodont - Triconodont - Tribosphenic - Euthemorphic Tooth becomes elongated mesiodistally, with smaller accessory cusps ; 3 basic cusps is the pattern Max molars: single triangle Mand molars: a single triangle with heel

Tooth formation (odontogensis)

Bud Stage: dental lamina invades underlying ectomesenchyme -forms tooth bud Cap Stage: dental lamina forms cap - enamel organ -enamel organ + condenced ectomesenchyme = dental papilla Bell Stage: clearly defined dental sac (follicle) -envelope of connective tissue surronding a developing tooth -enamel organ + dental papilla = dental sac

Crista Obliqua

Connects Protocone to the Metacone

Cristid Obliquid

Connects the Metaconid and the Hypoconid

Heterodony Origin

Derive multi-cuspidate, even quadritubercular, molars from simple conical teeth of a homodont - to tribosphenic molar

FDI

Each quadrant assigned # Max right: 1 Max left: 2 Mand left: 3 Mand right: 4 teeth in quadrants then assigned 1-8

Germ Layers

Ectoderm: external layer (skin, epithelium, enamel) -4 week: neural tube forms (neurulation) Mesoderm (mesenchyme): middle layer (skeleton, musculature, smooth cardiac muscle, dentine) Endoderm: internal layer (internal organs)

Making inferences from teeth

Get get information about: diet behavior life history population age-structure (demography)

Hertwig's epithelial root sheath (HERS)

Part of cervical loop that functions to shape the root(s) & induce root dentin formation.

Maxillary molars

Protocone, Paracone, Metacone, Hypocone

Mandibular molars

Protoconid, Hypoconid, Metaconid, Entoconid, Hypoconulid, Paraconid

Bilophodont

Refers to lower molars, in Old World monkeys, that have two ridges.

Universal System

Tooth 1: tooth farthest back on the right side of your mouth (maxillary) Tooth 16: farthest back on the left maxillary side Tooth 17: drop down on left side to farthest tooth in mandible Tooth 32: farthest tooth back on the right mandible

Acrodont

Tooth in very shallow basin (snakes, fish)

Tooth Identification/ numbering

Universal System Palmer (Zsigmondy) system FDI

cemento-enamel junction (CEJ)

Where the anatomical crown and root meet where cementum and enamel meet

Edentulous

Without (or only minimal) permanent teeth Edentata - anteaters, pangolins, sloths baleen whales

General Embryology

Zygote - the fertilized ovum Blastula - inner cell mass (5-7 days) Gastrula (from by Gastrulation) - hollow coped shaped structure with 3 layers of cells Trilamminar Disk - 3 cell layers (day 17) First tooth development: 14 weeks 37 days: epithelial band forms (ectodermal origin) Dental lamina: thickened band of ectoderm sitting on top of mesenchyme

dental emergence sequence

[I1 M1] I2 C [P3 P4 M2] M3 [ ] - variable in emergence = sequence polymorphism

Hypocone

a main cusp found on the distal lingual side of the upper molars. Genius: crushing function replaces shearing function Cusp enhances crushing/grinding functionality

Tomes process

a secretory surface of the ameloblast that is responsible for laying down and guiding the enamel matrix into place

Ectomesenchyme

a type of mesenchyme from the ectoderm, which is influence and forms all other tooth tissues Forms: dentine, pulp, cementum, periodontal ligaments, gingiva, alveolar bone

Hypodontia

absence of less than 6 teeth (not M3)

Oligodontia

agenesis of six or more permanent teeth

categories of emergence

alveolar emergence - appearance of tooth through crest of alveolar bone gingival "clinical" emergence - appearance of cusps of teeth through gingival margin (early/late stages) functional occlusion - reach occlusal plane, first appearance of wear (complete eruption)

cementochronology

annual lines acellular cementum - yearly layer down lines (TCA)

fossil hominid dental development

australopithecus - more similar to chimp dental chronology early homo - more similar to chimp dental chronology neanderthal - more similar to modern human dental chronology

Secodont

blade-like cusps

Bunodont

cheek teeth with low rounded cusps

linear enamel hypoplasia (LEH)

clear lines on teeth from development when something went wrong evidence of nutritional stress, emotional stress, illness,

Anodontia

congential absence of teeth true anodontia - all teeth missing hypodontia/ oligodontia - some teeth missing

cementogensis

creation of cementum cementoblasts - in the region of the root/ develop from the dental sac

Selenodont

crescent-shaped cusps

Lophodont

cusps form ridges

taurodentism

cynodont -normal pulp hypotaurodont - tall pulp root hypertaurodont -thick boy pulp roots

von ebner lines

daily cross striations in enamel short term daily growth of dentine -finer lines

tooth emergence v eruption

eruption - process of movement of teeth from their crypt into a functional position within oral cavity (process) emergence - appearance of any part of cusp or crown through gingival tissue (event)

acellular cementum

first cementum forms, covers half of root no cells

secondly dentine

formed after root formation represents continued, slower deposition of dentine Pulp recession - dentine fills in top of pulp chamber (back up dentine strengthens older teeth)

cellular cementum

forms after tooth reaches occlusal plane, irregular contains cells

dental sac (follicle)

forms: cementum, periodontal ligaments, alveolar bone

Quadritubercular (euthemorphic)

four main cusps arranged roughly as a square (e.g., some insectivores and primates)

enamel knot

group of cells in ectoderm that appears at a particular stage -first appear at cap stage -controls folding of inner enamel epithelium (primary) Secondary enamel knot: in molars to control folding in location of future cusps

cementum

hard, avascular connective tissue that covers the roots

Dentine

hard, dense, bony tissue forming the bulk of a tooth beneath the enamel. formed by: odontoblasts

Enamel

hardest tissue in human body, outermost layer of a tooth, exposed layer formed by ameloblasts that lose function after development 2 classes of protein: amelogenins and enamelins

Monophyodont

having one set of teeth

Homodont

having teeth that are uniform in form, shape, and function. most fish and tetrpods

Diphyodont

having two sets of teeth Decidious(20): incisors(2), canines (1), molars(2) Permanent(32): incisors(2), canines(1), premolar(2), molars(3)

Hypsodont

high crowned teeth

human v chimp molar emergence ages

human - 6, 12, 18 chimp - 3, 6, 9

dental papilla

inner mass of ectomesenchyme of tooth germ that produces dentin and pulp

dentine tubules

left behind by odontoblasts homologous to enamel prism part of odontoblast left behind in the tubules

primary dentine

lies between enamel and the pulp chamber circumpulpal dentine - around the pulp cavity mantle dentine - closer to enamel root dentine coronal dentine

Carnassial

long, sharp-edged teeth that meat-eating mammals have near the back of their jaws, used to slice through meat

Loxodont

lophodont teeth with very high, sharp ridges

Brachyodont

low crowned teeth

Zalambdodont

maxillary molars with "V-shaped" crest

Dilambdodont

maxillary molars with "W-shaped" crest

Polyprotodont

multiple lower incisors

Evolution of Teeth

outside in : long thought that dermal denticals (like in sharks) captured in stomodeum gave rise to teeth -ectodermal in origin - jut out of skin -similar components inside out: oral teeth arose by the progression of denticals from the pharynx to the stomodeum: pharyngeal jaws (like movie alien)

life history

pace of growth and development, and the timing of important 'milestones' in that development huge correlation between brain size and age at which the M1 emerges

Trigonid

paraconid, protoconid, metaconid

Polyphyodont

possessing an endless succession of teeth sharks, helicoprion

Hyperdontia

presence of supernumerary teeth

tertiary dentine

produced in reaction to stimuli/ insult made by odontoblasts affected by stimuli -local

schultz's rule

relationship between pattern of dental development and the overall pace of growth and maturation fast pace - fast dental development pattern slow pace - slow dental development pattern (greater body mass) tendency for replacement teeth to come in relatively early in slow-growing, longer-lived (larger bodied) species

enamel-dentine junction (EDJ)

remnant of inner enamel epithelium dentine horn - where primary/ secondary enamel knots were

Diprotodont

shortened mandible, first pair of lower incisors elongated to meet with upper incisors

Pulp

soft tissue within a tooth, containing nerves and blood vessels formed by: odontoblasts

striae of retzius

the position of the forming enamel front (all secretory ameloblasts line up on the same day)

Periodontum

tissues that anchor tooth to bone and nourish it

Thecodont

tooth rests in true bony socket (mammals, crocs)

Pleurodont

tooth rests on narrow bony ledge lingually (lizards)

sequence polymorphism

variable in emergence of teeth between people

perikymata

wave-like lines that run around the crown -on labial surface of incisors -buccal/ lingual surfaces of molar -external manifestation of internal striae of retzius

cervical loop

where inner and outer epithelium intersect

tooth anatomy

*Crown*: part visible above the gingiva and is covered by enamel *Root*: fixed in the tooth socket by the peridontium, their number varies *Neck*: between the crown and root - Each tooth is contains a cavity that is filled with pulp and the extension of pulp into the root is the root canal

Molars

Most posterior teeth, largest surface area/ crestiness Crushing, grinding, shearing function mammals: reduced - usually 3

Palmar (zsignmondy) System

Mouth divided into 4 quadrants 1: first incisor 8: third molar numbers sit in L-shaped symbol used to identify quadrant

dental directional terms

Mesial: surface directed toward the first incisor Distal: surface directed away from first incisor Lingual/Palatal: surface of a tooth facing the tongue Vestibular/Labial: surface of tooth facing lips Buccal: surface of tooth facing cheek Incisal: biting surface of anterior teeth Occusal: chewing surface of posterior teeth Interproximal: between the teeth

Heterodont

Having different kinds of teeth; characteristic of most mammals, whose teeth consist of incisors, canines, premolars, and molars.

Homeobox v Hox genes

Homeobox : regulation of patterns of development -arms, legs, butt, head Hox genes: determining patterning on smaller scale -parts of head

Talonid

Hyponid, Entoconid, Hypoconulid

Amelogenesis

II Secretory phase: nucleus (ameloblast makes 1 prism) -tall columnar cell; nucleus away from "business end" -Tomes process -secretes crystallites arranged into rids or enamel prisms -immature enamel -hydroxyapatite III Maturational: -Tome's process goes away -striated border -immature enamel -mature enamel -loss of H2O and organic matrix -leftover: highly inorganic/ mineralized

andresen lines

Long-period lines in dentine

Incisors

Mesial teeth shovel shaped : spatulate nipping/ cropping function placentals: never have more than 3

Cementum

Specialized, calcified connective tissue that covers the anatomic root of a tooth. Attachment site of the periodontal ligaments Forms continuously during life

Canines

Teeth in front of the premolars that rip and tear food. long; unicuspid behavioral function placentals: never more than 1 per quadrant

Successional lamina

That portion of the dental lamina lingual to the developing deciduous teeth, which gives rise to the enamel organs of permanent teeth.

dental formula

The numerical description of a species' teeth, listing the number, in one quadrant of the jaws, of incisors, canines, premolars, and molars.

Premolars

The teeth immediately behind the canines; used in chewing, grinding, and shearing food. The bicuspid teeth cheek teeth placentals: never more than 4