237 Oral Anatomy And Histology Midterm

Front 1

bilaterally symmetrical

Back 1

left and right sides of the body are mirror images of each other

Front 2

vertical and horizontal overlap

Back 2

The outline of the maxillary arch is somewhat larger than that of the lower arch. This creates the normal biting relationship in which there is vertical and horizontal overlap of the maxillary teeth.

Front 3

occlusal plane

Back 3

divides the mouth into upper and lower halves

Front 4

mid-sagittal plane

Back 4

divides each arch into right and left halves.

In dentistry, the mid-sagittal plane is more often referred to as the midline or median line

Front 5

Primary vs. permanent

Back 5

Primary DentitionIn each quadrant of the mouth, there are two incisors, one cuspid and two molar teeth. In total, there are 5 primary teeth.

Permanent DentitionIn each quadrant of the mouth, there are two incisors, one cuspid, two bicuspids, and three molar teeth. In total, there are 8 permanent teeth.

Front 6

anatomical crown VS. clinical crown

Back 6

The anatomical crown is the whole crown of the tooth, whether it has erupted or not. The clinical crown is the part of the tooth that can be seen in the mouth.

Front 7

Roots

Back 7

The root portion or system of a tooth may be single or multiple with bifurcation or trifurcation, that is, division of the root trunk into two or three roots.

Front 8

Enamel

Back 8

-forms the outer surface of the anatomical crown

-thickest at the tip of the crown and becomes thinner until it ends at the cervical line

-color varies with its thickness, mineralization, and skin pigmentation

-hardest tissue in the human body

-has the ability to resist the stress that the crown -is subjected tois smooth – gives it a certain "self cleansing" ability

-extreme hardness and resistance to wear make it a nearly perfect outer covering for the crown

-line marking the junction of the dentin and enamel is referred to as the dentinoenamel junction

Front 9

Dentin

Back 9

-forms the main portion or body of the tooth

-hard, dense calcified tissue

-softer than enamel but harder than cementum or bone

-is capable of continuous formation

-secondary dentin (new dentin) is formed throughout the pulp chamber after the tooth erupts.

-In time, secondary dentin could entirely fill the pulp cavity.

Front 10

Cementum

Back 10

-calcified substance that covers the root of the tooth

-main function is to provide a means for the attachment of the tooth to the alveolar bone

-denser than bone but not as dense as dentin or enamel

-least calcified tooth tissue (softest)cementum is quite thin at the cervical line but increases slightly in thickness at the apex of the root

-line indicating where the dentin joins the cementum is referred to as the dentinocemental junction

Front 11

Pulp

Back 11

-pulp is the nourishing, sensory and dentin–reparative system of the tooth

-composed of blood vessels, lymph vessels, connective tissues, nerve tissue and odontoblasts which are special dentin formation cells

-housed in the centre of the tooth, surrounded by dentin

-only sensation pulp responds to is pain

-anatomically, the pulp is divided into two areas: the pulp chamber (which is housed within the coronal portion of the tooth) and the pulp canal (which is located within the roots of the tooth)

-the pulp chamber and the pulp canal are referred to as the pulp cavity

-the pulp tissue which extends towards the cusps or incisal corners is called a pulp horn

Front 12

axial surface

Back 12

Any surface of a tooth that is parallel to the long axis of the tooth

Front 13

proximal surface

Back 13

The surface of a tooth that faces the neighbouring tooth's surface in the same arch (next to each other)

Front 14

Division of Surfaces

Back 14

The lingual and buccal surfaces of a tooth are divided into a mesial, middle and a distal third.

The mesial and distal surfaces of a tooth are divided into a facial, a middle and a lingual third.

The buccal and lingual surfaces of a posterior tooth can also be divided into an occlusal, middle and cervical third.

The labial and lingual surface of an anterior tooth can be divided into an incisal, middle and cervical third.

The root of a tooth can be divided transversally into an apical, middle and cervical third.

Front 15

Line Angles

Back 15

Front 16

Point Angles

Back 16

Front 17

Height of Contour

Back 17

widest point on a specific surface of the crown of a tooth

Front 18

Embrasure

Back 18

An embrasure is the V-shaped space between the proximal surface of two teeth in contact in the arch.

Front 19

Cusp

Back 19

Anterior teeth, most bicuspids and second molars develop from four lobes while first molars develop from five lobesmound on the crown portion of a tooth that makes up a major division of its occlusal surface .Found on cuspids, bicuspids and molars

Front 20

Tubercle

Back 20

mall "cusp-like" elevation on some portion of a tooth, crown, usually on the lingual surface.

Front 21

Cusp of Carabelli

Back 21

Extra cusp on the mesial-lingual surface of the upper first permanent molar

Front 22

Cingulum

Back 22

A bulge of enamel found on the cervical third of the lingual surface of anterior teeth

Front 23

Mamelon

Back 23

Rounded prominence on incisal edge of newly erupted incisors (wears off)

Front 24

Groove

Back 24

Channel (or hollow) made to direct motion or to receive a corresponding ridge.

Front 25

Developmental Groove

Back 25

Shallow depression lines in the enamel of a tooth that mark the union of the lobes of the crown.

Front 26

Fissure

Back 26

Deep cleft: developmental line fault as a result of the imperfect fusion of the enamel of adjoining dental lobes

Front 27

Pit

Back 27

A small pinpoint depression– usually occur along the developmental grooves or in the fossae.

Front 28

Fossa

Back 28

depression or concavity

area on the tooth that is indented

named by location

Front 29

Ridge

Back 29

linear surface of the tooth

Front 30

Cusp Ridge (cusp slope)

Back 30

inclined surface or ridges that form an angle at the cusp tip when viewed from the buccal or lingual aspect

Front 31

Marginal Ridge

Back 31

linear elevation that form the mesial and distal shoulders of the occlusal surface and the mesial and distal shoulders of the lingual surface of anterior teeth

Front 32

Transverse Ridge

Back 32

union of two triangular ridges, a buccal and lingual, that cross the occlusal surface of a posterior tooth (ML – MB or DL – DB)

Front 33

Triangular Ridge

Back 33

the main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface

Front 34

Oblique Ridge

Back 34

a ridge on Mx molars that crosses the occlusal surface from the disto-buccal cusp to the mesio-lingual cusp.

Front 35

Functions of the lips

Back 35

help take food and liquid into the mouth

prevent ingestion of extremely hot or cold substances

seal for the mouth (keeps food/liquids and saliva from escaping)

helps to maintain the position of the teethspeechexpel air

Front 36

vermillion zone

Back 36

reddish tissue known as the vermillion zone (area) of the lip

Front 37

vermillion border

Back 37

the line of demarcation between the vermillion zone and the skin of the face

Front 38

philtrum

Back 38

The skin of the upper lip has an indentation extending from the area below the middle of the nose to the center of the upper lip

Front 39

naso-labial sulcus

Back 39

shallow depression extending from the corner of the nose to the corner of the mouth

Front 40

labio-mental groove

Back 40

shallow linear depression between the center of the lower lip and chin

Front 41

labio-marginal sulcus

Back 41

shallow depression extending downward from the corners of the mouth

Front 42

Commissure

Back 42

corner of the mouth

Front 43

Functions of the oral cavity

Back 43

mastication

moisten food with saliva, preparing it for swallowing and digestion

sense of taste

moves food around the oral cavity

air passage

speech

Front 44

Mucous membrane

Back 44

lines the oral cavity. This soft, pink, moist tissue is called the oral mucosa and occurs in varying thicknesses. It acts as a protective covering for the oral cavity. In some areas, it is firmly attached to the underlying bone and in other areas it is looser.

Front 45

There are three types of oral mucosa

Back 45

1. Masticatory Mucosa - covers areas subject to stress

2. Specialized Mucosa - covers the area that has the specific function of taste

3. Lining Mucosa - covers all other areas of the oral cavity

Front 46

palate

Back 46

roof of the mouth defines the superior border while the tongue and floor of the mouth is the inferior boundary.

Front 47

palatine tonsils

Back 47

lie on the sides of the throat between two folds of tissue

Front 48

mucobuccal or mucolabial fold

Back 48

the point at which the mucosa of the cheeks or lips turns to go towards the "gums".

Front 49

mucogingival junction

Back 49

the point at which the mucosa becomes tightly attached to the alveolar bone and is the beginning of the gingiva.

Front 50

labial frenum

Back 50

Pull outward on the lips or corners of the mouth and you will see several areas where the tissue is attached in folds to the alveolar mucosa. At the mid-line in both the upper and lower lips, there is a fold of tissue

A frenum is a narrow fold of mucous membrane passing from a more fixed to a moveable part.

Front 51

Stenson's papilla

Back 51

a small, raised flap of tissue on the buccal mucosa opposite the upper second molar. It is often marked with a tiny red dot which is the opening to the Parotid or Stenson's gland. It can also be called the Parotid papilla.

Front 52

Linea alba

Back 52

a raised, white horizontal extension of soft tissue along the buccal mucosa at the occlusal line.

Front 53

maxillary tuberosity

Back 53

a small, rounded extension of bone, covered with soft tissue, is found posterior to the last maxillary tooth

Front 54

retomolar area

Back 54

triangular area of bone, covered with soft tissue, posterior to the last mandibular tooth.

Front 55

Exostoses

Back 55

small bony growths on the buccal cortical plate of the vestibule in a large portion of the population. They are normally of no consequence.

Front 56

bony eminence

Back 56

raised contour of bone, covered with soft tissue, that follows the roots of the teeth, in particular, the canine eminence.

Front 57

Hard Palate

Back 57

The hard palate serves as the bony roof of the mouth and separates it from the nasal cavity.

Front 58

rugae

Back 58

transverse ridges of tissue found in the anterior portion of the hard palate

Front 59

palatine raphe

Back 59

which is a ridge of tissue running down the mid-line of the palate

Front 60

fovea palatinus

Back 60

Two small indentations, one on either side of the raphe, called fovea palatinus, are located at the junction of the hard and soft palate. These are remnants of minor salivary glands.

Front 61

incisive papilla / incisive foramen

Back 61

singular bulge of tissue at the mid-line immediately behind the maxillary central incisors. Beneath this papilla is the incisive canal, which carries a nerve to the soft tissue lingual to the maxillary anterior teeth, a point of injection for anaesthetizing the palatal gingiva adjacent to the maxillary anterior teeth.

Front 62

torus palatinus.

Back 62

excess bony growth in the mid-line of the hard palate

Front 63

Functions of the hard palate

Back 63

-crush foods in preparation for swallowing

-assists in swallowing

-helps prevent injury to the oral structures by determining texture and temperature of food

Front 64

Soft Palate

Back 64

The posterior third of the palate is called the soft palate. It is composed of muscular fibres covered with mucosa and is a deeper pink colour than the hard palate because of its highly vascular composition.

During speaking or swallowing, the soft palate is elevated and pulled backwards, closing off the nasal cavity

Front 65

uvula

Back 65

The most posterior portion at the mid-line is a downward projection

Front 66

Oropharynx

Back 66

The following structures are located at the posterior portion of the oral cavity:

fauces – arch or entryway that joins the oral cavity with the pharynx, also called the oro-pharynx

pillars of fauces – two folds of tissue on either side, one behind, one in front of, the tonsils

palatopharygneal arch or fold – more prominent fold, behind the tonsil, also call the posterior pillar

palatoglossal arch or fold– immediately in front of the tonsil, also called the anterior pillar

palatine tonsils – masses of lymphoid tissue located between the anterior and posterior pillars of fauces

Front 67

lingual frenum

Back 67

Extending from an area near the tip of the tongue down to the floor of the mouth is a fold of tissue

Front 68

sublingual caruncle

Back 68

At the base of the frenum, there is a small elevation on each side. This is the opening for salivary glands.

Front 69

sublingual fold

Back 69

Extending from the sublingual caruncle back along the floor of the mouth on either side of the mouth, is a fold of tissue. containing a number of small openings or ducts of the sublingual salivary gland.

Front 70

mandibular tori

Back 70

bony projections on the lingual surface of the lower jaw at the cuspid-bicuspid area

Front 71

The Tongue

Back 71

The tongue is an epithelial sac filled with muscles. The base is attached to the floor of the mouth, while the anterior portion is free.

Front 72

dorsum

Back 72

he upper surface of the tongue

Front 73

ventral

Back 73

The under surface of the tongue

Front 74

median sulcus

Back 74

The slight depression in the mid-line

Front 75

papillae

Back 75

The dorsal surface of the tongue is covered with a thick, highly specialized epithelium through which are scattered four types of elevated structures

contain the organs of taste.

Front 76

Circumvallate or vallate papillae

Back 76

form a V-shaped row of circular raised papillae about two-thirds of the way back on the tongue

Front 77

Fungiform papillae

Back 77

appear as tiny, round, raised spots on the anterior two-thirds of the tongue.

Front 78

Filiform papillae

Back 78

tiny, pointed projections of epithelial tissue, covering the anterior two-thirds of the tongue. They have no taste function but provide tactile sensation

Front 79

glossitis

Back 79

Sometimes, the epithelium of these papillae are lost and the surface of the tongue becomes very smooth.

Front 80

foliate papillae

Back 80

If you grasp the tip of the tongue with a piece of gauze and gently pull it out and to the side, you will see a roughened lateral surface back in the region of the vallate papillae. These are the foliate papillae. They are not well developed but do contain some taste buds.

Front 81

lingual tonsils

Back 81

region near the mid-line on the dorsum of the tongue, just behind the vallate papillae. his is tissue similar to that of the palatine tonsils and provides a defense mechanism in that area

Front 82

Functions of the tongue

Back 82

crushes food against the hard palate

pushes food between the occlusal surfaces of the teeth

transfers food from one area of the mouth to another

mixes food with saliva

selects the parts of the masticated mass that is ready to be swallowed

assists in swallowing

after swallowing, it helps to cleanse the mouth of food residue

important in the formation of speech sounds

Front 83

Types of numbering systems

Back 83

Universal- 1-32

F.D.I. (Federation Dentaire Internationale)- quad # then 1-8

Palmer-Using this system, the mouth is also divided into quadrants. A symbol is used to indicate the quadrant (vertical and horizontal line). then 1-8

Primary use quad 5-8. and Letters instead of #'s

Front 84

Organizational Levels

Back 84

LEVEL 1 - Cells

• Are the basic unit of structure and function in living things.

• May serve a specific function within the organism

LEVEL 2 - Tissues

• Made up of cells that are similar in structure and function and which work together to perform a specific activity

LEVEL 3 - Organs

• Made up of tissues that work together to perform a specific activity

LEVEL 4 - Organ Systems

• Groups of two or more tissues that work together to perform a specific function for the organism.

LEVEL 5 - Organisms

• Entire living things that can carry out all basic life processes. Meaning they can take in materials, release energy from food, release wastes, grow, respond to the environment, and reproduce.

• Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria or protist.

Front 85

Body Systems

Back 85

The human body has 10 systems:

(1) skeletal

(2) muscular

(3) cardiovascular (including the lymphatic and immune systems)

(4) nervous

(5) respiratory

(6) digestive

(7) endocrine

(8) urinary

(9) integumentary (skin)

(10) reproductive.

Front 86

Nervous system

Back 86

Front 87

Epithelial Tissue

Back 87

covers and lines the external and internal body surfaces and serve as a protective covering or lining. They are also involved in tissue absorption, secretion, sensory and other specialized functions.

1. Simple (single layer)

2. Stratified (more than 1 layer)

3. Pseudostratified (appear stratified, but are actually in a single layer)

The shape of epithelial cells is described by the words squamous (Flattened), cuboidal (square) and columnar (rectangular)

Front 88

Connective Tissue

Back 88

is the most abundant type of basic tissue in the body. It is usually composed of cells spaced apart and large amounts of matrix between the cells. Connective tissue is involved in support, attachment, packing insulation, storage, transport, repair and defense.

Front 89

Muscle Tissue

Back 89

part of the muscular system. They have the ability to lengthen and shorten which produces movement of body parts.

Front 90

Nerve Tissue

Back 90

forms the nervous system of the body. They are responsible for coordinating and controlling body activities. They carry messages or electrical impulses from all areas of the body to the brain and from the brain to various areas of the body.

Front 91

Embryonic Germ layers

Back 91

During the third week of development, the cells of the embryo form the three primary

embryonic layers:

1. Ectoderm (outer layer) → epithelium covering outside body and lining the oral cavity, nasal cavity, sinuses, tooth enamel and nervous system

2. Mesoderm (middle layer) → skeletal system, muscles, blood, lymph, kidneys and other internal organs

3. Endoderm (inner layer) → epithelial lining of pharynx, stomach, intestines, lungs, bladder, urethra, vagina

Front 92

Establishment of the Primitive Mouth

Back 92

-fourth week of prenatal development, within the embryonic period.

-During this time, the rapidly growing brain of the embryo bulges over the oropharyngeal membrane and developing heart. All three embryonic layers are involved in facial development: ectoderm, mesoderm, and endoderm.

Front 93

Stomodeum and oral cavity formation

Back 93

The stomodeum (primitive mouth) appears as a shallow depression in the embryonic surface ectoderm at the cephalic end before the fourth week.

Front 94

Mandibular arch and lower face formation

Back 94

After formation of the stomodeum, two bulges of tissue appear inferior to the primitive mouth, the two mandibular processes.

These processes consist of a core of mesenchyme.

-These paired mandibular processes fuse at the midline to form the mandibular arch.

- After fusion, the mandibular arch then extends as a band of tissue inferior to the stomodeum

-The mandibular arch directly gives rise to the lower face, including the lower lip.

Front 95

Frontonasal process and upper face formation

Back 95

The frontonasal process forms as a bulge of tissue in the upper facial area.

On the outer surface of the embryo are placodes, which are rounded areas of specialized, thickened ectoderm found at the location of developing special sense organs.

The facial area of the embryo has 2 lens placodes, which are initially located fish-like on each side of the frontonasal process.

The tissue around the nasal placodes on the frontonasal process undergoes growth, starting the development of the nasal region and the nose.

The placodes become submerged, forming a depression in the center of each placode, the nasal pits.

The middle part of the tissue growing around the nasal placodes appears as two crescent‑shaped swellings located between the nasal pits. These are the medial nasal processes.

On the outer part of the nasal pits are two other crescent‑shaped swellings, the lateral nasal processes.

Front 96

Maxillary process and midface formation

Back 96

During the fourth week of prenatal development, an adjacent swelling forms from increased growth of the mandibular arch on each side of the stomodeum, the maxillary process.

Each maxillary process will grow superiorly and anteriorly around the stomodeum.

The upper lip is formed when each maxillary process fuses with each medial nasal process on both sides of the stomodeum due to the underlying growth of the mesenchyme.

The maxillary processes contribute to the sides of the upper lip, and the two medial nasal processes contribute to the philtrum.

Front 97

Development of the Neck

Back 97

Beneath the stomodeum, five paired branchial arches form, in the region of the future neck.

These are designated as branchial arches I, II, III, IV, and V.

Immediately below the stomodeum is the first branchial arch, which will develop into:

2 maxillary processes

2 mandibular processes

All parts of the oral and nasal cavities now develop from the frontal process and the first branchial arch (except for parts of the tongue).

Front 98

Branchial Arch

Back 98

Right and Left maxillary process- Upper cheeks, sides of the upper lip and most of palate

Right and Left mandibular process- Lower cheeks, lower lip, lower jaw, part of tongue

Front 99

Development of Oral and Nasal Cavity

Back 99

Develop during the fourth to twelfth week of prenatal development

Front 100

Palate Development

Back 100

The formation of the palate starts during the fifth week of prenatal development, within the embryonic period.

The palate at this time is formed from two separate embryonic structures: primary palate and secondary palate.

The palate is then completed later during the twelfth week, within the fetal period.

Front 101

Nasal Septum

Back 101

The nasal cavity forms in the same time frame as the palate, from the fifth to twelfth week of prenatal development.

Front 102

Development of the Tongue

Back 102

The tongue develops as growths from the mid-anterior region on the inner surface of the first four brachial arches:

anterior of tongue ← 1st Branchial arch

posterior of tongue ← 2nd, 3rd, and 4th Branchial arches

Front 103

inside of Branchial arch areas

Back 103

Middle ear

Thyroid Gland (in neck)

Parathyroid Gland (in neck)

Front 104

Epithelial Rests

Back 104

-misplaced clumps/groups of epithelial cells

-lodged between embryonic processes that are coming together

-these cells come from the ectoderm germ layer -cause formation of cysts

-clump of epithelial cells divide to form a sac

-cysts can grow and distort tissues/teeth

Front 105

The Beginning of Tooth Development (odontogenesis)

Back 105

1. Not all teeth begin developing at the same time:

tooth development begins in mandibular midline area at 5th – 6th week in utero

tooth development continues in anterior maxillary midline areatooth development progresses posteriorly in both jaws

2. A tooth arises from epithelial and connective tissue (mesenchyme)both are derivatives of ectodermal germ layer

Front 106

Enamel Organ

Back 106

originates from dental lamina

thickening of epithelium

ectodermal germ layer

will form enamel

Front 107

Dental Papilla

Back 107

connective tissue under enamel organ

originates from mesenchyme

ectodermal germ layer

will form dentin and pulp

Front 108

Dental Sac

Back 108

fibrous cell layer

originates from mesenchyme

ectodermal germ layer

will form periodontal ligament, lamina dura and cementum

Front 109

Bud Stage

Back 109

Primary Dental Lamina (beginning of 8th week)

thickened oral epithelium, proliferation of the cells of the dental lamina

formation of 10 buds on the maxilla and 10 on the mandible

grow into underlying mesenchyme (connective tissue)

forms enamel organ

Front 110

Cap Stage

Back 110

(9 – 10 weeks)

-Mesenchyme cells differentiate and grow under the enamel organ

-Unequal growth in different parts of the tooth bud, leading to formation of a cap shape attached to the dental lamina.

-A primordium of the tooth develops with a specific form: the tooth germ.

-A depression results in the deepest part of each tooth bud of dental lamina and forms a cap, or enamel organ

-A part of the mesenchyme deep to the buds condenses into a mass within the concavity of the cap of the enamel organ.

-This inner mass of ectomesenchyme is called the dental papilla.

-The dental papilla will produce the future dentin and pulp for the inner part of the tooth.

-A basement membrane still exists between the enamel organ and the dental papilla and is the site of the future dentinoenamel junction (DEJ).

Front 111

Bell Stage

Back 111

(11 – 12th weeks)

1. Outer Enamel Epithelium (OEE)

- cuboidal cells

-protective layer

2. Inner Enamel Epithelium (IEE)

- single layer of cuboidal cells

-lines inside (concave area)

-future ameloblasts

-separated from dental papilla by basement membrane

3. Stellate Reticulum (SR)

-inside OEE

-protection/cushion

-transport nourishment to IEE

-composed of a loose network of star-shaped epithelial cells

4. Stratum intermedium (SI)

-inside SR

-between SR and IEE

-flat cells

-directly nourishes IEE

Front 112

Basement Membrane

Back 112

-between dental papilla and IEE

-fixed and determines final shape of tooth

-further cell differentiation and growth occurs around basement membrane (BM)

-IEE → ameloblasts – top of BM

-Dental papillae → odontoblast – below BM

-future DEJ

Front 113

Secondary Dental Lamina

Back 113

-before enamel and dentin formation begins

-primary dental lamina breaks from oral epithelium

-formation of secondary dental lamina → permanent or succedaneous tooth

Front 114

Dentin Formation (dentinogenesis)

Back 114

-1st mineralized layer of any developing tooth

-Dentin is first formed at the incisal/cusp area of a tooth and progresses in a root ward direction

-odontoblast

-“attached” to basement membrane (DEJ)

-create narrow extensions as they grow → tubules surround the cell

-the nucleus continues moving away from DEJ in narrow extensions

-odontoblastic process remains in tubule

-also cork secured collagen fibers

-mineralization begins at DEJ and moves downward (pulpal)

Front 115

Enamel Formation (amelogenesis)

Back 115

-product of the enamel organ

-begins after dentin begins, at the dentin surface of the cusp/incisal edge

-ameloblasts move upward and outward leaving an organic enamel matrix

-enamel rods and inter-rod substance (enamel matrix)

-crystal formation – 96% mineralized

NOTE: IEE cells become ameloblast cells

Front 116

Primary Enamel Cuticle

Back 116

-produced by ameloblasts after enamel formation complete

-smooth coating over enamel

Front 117

Remaining Original Layers

Back 117

-stellate reticulum, stratum intermedium, outer enamel epithelium and ameloblast cells

-reduced to few layer of cells known as the reduced enamel epithelium

-reduced enamel epithelium (REE) which produces secondary enamel cuticle

-part of the REE attaches to the oral epithelium as the tooth erupts

-future junctional epithelium

Front 118

Secondary Enamel Cuticle

Back 118

-protects tooth until eruption

-non-mineralized

Front 119

Root Formation

Back 119

The process of root development takes place after the crown is completely shaped and the tooth is starting to erupt into the oral cavity.

-continues after enamel complete

-dentin surrounds pulp chamber

-continues as tooth develops

-complete 1-4 years after eruption

-The structure responsible for root development is the cervical loop. The cervical loop is the most cervical part of the enamel organ, a bilayer rim that consists of only IEE and OEE.

-It begins to grow deeper into the surrounding mesenchyme of the dental sac, elongating and moving away from the newly completed crown area to enclose more of the dental papilla tissue and form Hertwig epithelial root sheath (HERS).

-This sheath or membrane shapes the root(s) and induces dentin formation in the root area, so that it is continuous with coronal dentin.

Front 120

Periodontal Ligament and Cementum

Back 120

-dental sac cells surround developing dentin (root)

-the circularly arranged fibers of the dental sac become the Periodontal Ligament (PDL) around the tooth root

-the PDL produces the cementum that covers the root dentin and the lamina dura of the tooth socket

-fibers of the PDL become trapped in their substance (as it forms cementum and lamina dura)

-the eventual attachment of the PDL fiber in the cementum and lamina dura holds the tooth in the socket

Front 121

Supraeruption

Back 121

this occurs when there is a loss of an opposing tooth; this condition allows the tooth or teeth to erupt farther than normal into the space; this can mean serious problems in replacement of missing teeth with a partial denture or fixed bridge

Front 122

The Process of Primary Tooth Shedding (Resorption and Exfoliation)

Back 122

-the shedding of primary teeth takes place because of the gradual resorption (disintegrating or eating away of organic material) of their roots and loss of periodontal ligament attachment.

-the developing permanent tooth located lingual to or beneath the root of the primary tooth, creates sufficient pressure because of it’s increasing crown size to cause resorption of the primary tooth root and of the bone surrounding this primary tooth root.

-as the root resorbs, the tooth loosens

-eventually all the periodontal ligament of the primary tooth is lost and the rootless primary crown literally falls off the jaw.

-EXFOLIATE means to fall out.

-regardless of its position, the fact that the permanent tooth crown is present and that its root is developing, causes the permanent tooth crown to move occlusally toward the surface of the oral cavity. This creates pressure on the root of the primary tooth. It is believed that this pressure promotes “osteoclasts” to form and begin resorbing the primary tooth root (also dentinoclast and cementoclast).

-“resorption” of a primary tooth takes place for about one year prior to “exfoliation”

Front 123

Ankylosis

Back 123

-the term “ankylosis” refers to the union of 2 similar or dissimilar hard tissues previously detached but beside each other.

-secondary tooth unable to erupt until the ankylosed tooth is removed or until the permanent tooth deviates from its path of eruption and emerges (erupts) out of alignment

Front 124

Ectopic Teeth

Back 124

out of place arising or produced at an abnormal site

Front 125

Primary Tooth Eruption

Back 125

RULE: mn > mx

a) 1’s 6-7 months

b) 2’s 9 months

c) 4’s 12 months

d) 3’s 16 months

e) 5’s 24 months

Sequence 1, 2, 4, 3, 5

Front 126

Primary/Deciduous Characteristics differing from Permanent Counterparts

Back 126

-Anterior teeth have smaller crowns and roots

-Have no mamelons

-Molars are wider mesial to distal than permanent bicuspids

-Narrower roots and longer in comparison with crown length

-Narrow cementoenamel junction

-Cervical ridge of enamel at the cervical third of the crowns of deciduous anterior teeth are very prominent labially and lingually.

-Buccocervical ridges of molars are much more pronounced creating a more bulbous or "bell-shaped" appearance

-Roots are more slender and longer and flare apically to allow room in between for the developing permanent tooth crowns.

-Lighter in colour more white with a bluish cast

-Pulp chambers are large comparatively to crown size

-Pulp horns extend more occlusally

-Less dense pulpLess dense enamel with inconsistent depth

Front 127

primate spaces

Back 127

the space mesial to the maxillary cuspids and distal to the mandibular cuspids.

Front 128

leeway space

Back 128

spaces between 1 and 2 primary molars.

allow an extra margin of space for eruption of the permanent cuspid, fist and second bicuspid

Front 129

mesial step

Back 129

the lower molars are situated more mesially than their maxillary counterparts.

Front 130

flush terminal plane

Back 130

the distal surfaces of the primary second molars even with each other.

Front 131

distal step

Back 131

mandibular molars are situated more distally than their maxillary counterparts.

Front 132

succedaneous teeth

Back 132

With every primary tooth in the mouth there is a corresponding permanent tooth that retains space for their permanent successors. The replacing permanent successors are referred to as succedaneous teeth. Not all permanent teeth, however, are succedaneous (meaning there was no matching primary tooth).

Front 133

Primary exfoliation

Back 133

central incisors- 6-7 years

lateral incisors- 7-8 years

cuspid- 9-12 years

first molar- 9-11

second molar- 10-12

Front 134

Permanent teeth eruption

Back 134

central incisors- 7-8 years

lateral incisors- 8-9

cuspid- 11-12

first pre-molar- 10-11

second pre-molar- 10-12

first molar- 6-7

second molar- 12-13

third molar- 17-21