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Human Dentition
DENTAL ANATOMY NOMENCLATURE
The Jaws
DENTAL ARCHES
• A. THE MAXILLA
is two bones forming
the upper jaw; they are rigidly
attached to the skull.
B. THE MANDIBLE
is a horse-shoe shaped bone which articulates with the skull by way of the temporo-mandibular joint the TMJ.
Quadrants:right & left quadrants
Maxillary right and left.
Mandibular right and left.
4 Quadrants
Functions of Teeth
*Efficient mastication of food.
*Maintenance of a normal facial appearance.
*Formulation of clear speech.
Incisor Canine Premolar Molar
1- Mastication:
Incisors Canine Premolar Molar
Chisel like Cutting or
incising
Wedge like
Cutting and
tearing
At least two projections
(cusps.) Tearing and
grinding
Multiple projection
s (cusps )
Grinding
4- Growth of jaws:The teeth play a role in the growth of the jaws in some periods of life.
2- Appearance: - Well arranged clean teeth with proper alignment give nice appearance to the face. – Teeth give support to the facial expressions.
3- Speech: for clear pronunciation and production of sound.
Types of
Teeth
Anterior Teeth
for cutting &
tearing foodPosterior Teeth
•Incisors function as cutting or shearing
instruments for food.
•Canines possess the longest roots of all teeth
and are located at the corners of the dental
arch.
•Premolars act like the canines in the tearing
of food and are similar to molars in the
grinding of food.
•Molars are located nearest the
temporomandibular joint (TMJ), which serves
as the fulcrum during function.
Anterior Teeth- Upper CanineCentral
Incisorslateral
Anterior Teeth- Lower
lateral CanineCentral Incisors
PREMOLARS: (IN PERMANENT ONLY)
First premolar & Second premolar
Upper
Lower
Molars
First second Upper
Lower
Wisdom tooth =Third permanent molar
Single-rooted
Multi-rooted
Types of Dentitions:Primary & Permanent Dentition
• Deciuous Set of Teeth.: – 2 incisors, – 1 canine,– 2 molars in each quadrant
• Permanent Set of Teeth.:– 2 incisors,– 1 canine, – 2 premolars,– 3 molars in each quadrant
Types& forms:
Types of
Dentitions:
I-Primary
Dentition
a. Twenty ( 20) primary teeth. b. 10 in each arch c. 5 in each quadrant
In function: 2 years 12 years
6 years 12 years
Eruption of first permanent
molar
Shedding of last primary
molar
Deciduous ,baby, milk teeth:
ERUPTIONFrom 6 months to 2 years:
pure deciduous dentition
* At three years all roots are complete
From 6y to 12 y:
mixed dentition
From 12 y onwards:
pure permanent dentition
Mixed Dentition
Period
6 years ERUPTION OF FIRST PERMANENT MOLAR
In function: 12 years
through out life
SURFACES OF TEETH ARE IDENTIFIED BY THE RELATIONSHIP TO SURROUNDING OROFACIAL STRUCTURES
•Apical•Labial•Lingual•Distal•Mesial•Incisal
Teeth: Identification Tooth Surfaces
Labial
Apical
Lingual
Distal
Apical
Mesial
Incisal Incisal
Each tooth has Five surfaces:
•Apical: Pertaining to the
apex or root of the tooth
•Labial: Pertaining to the
lip; describes the front
surface of anterior teeth
•Lingual: Pertaining to
the tongue; describes the
back (interior) surface of
all teeth
•Distal: The surface of the
tooth that is away from
the median line
•Mesial: The surface of
the tooth that is toward
the median line
palatal
Functioning Surfaces:
OCCLUSAL: chewing surfaces of
posterior teeth
INCISAL: the anteriors’ biting
surface
chewing/biting surfaces of teeth:
Enamel
Alveolar Bone
PulpChamber
Oral Anatomy and Physiology
•Enamel•Dentin•Pulp Chamber•Odontoblast Layer•Periodontal Ligament•Gingiva•Alveolar Bone•Cementum•Pulp Canals•Apical Foramen
The Dental Tissues:Dentin
Odontoblast Layer Gingiva
Periodontal Ligament
Cementum
Pulp Canals
Apical Foramen
•Anatomic Crown
•Anatomic Root
•Pulp Chamber
The 3 parts of a tooth: Anatomic Crown
Anatomic Root
PulpChamber
Oral Anatomy and Physiology
Anatomic Crown
Anatomic Root
PulpChamber
Oral Anatomy and Physiology
•THE ANATOMIC CROWN is the portion of the tooth covered by enamel.
•THE ANATOMIC ROOT
is the lower two thirds of a tooth.
•THE PULP CHAMBER
houses the dental pulp, an organ of myelinated and unmyelinated nerves, arteries, veins, lymph channels, connective tissue cells, and various other cells.
Oral Anatomy and Physiology
•ENAMEL•DENTIN•CEMENTUM•DENTAL PULP
The 4 main dental tissues:
Enamel
Dentin
Cementum
Dental Pulp
•STRUCTURE•Highly calcified and hardest tissue in the body•Crystalline in nature•Enamel rods
•INSENSITIVE—no nerves•Acid-soluble—will demineralize at a pH of 5.5 and lower •Cannot be renewed•Darkens with age as enamel is lost•Fluoride and saliva can help with remineralization
DENTAL TISSUES—ENAMEL2
• ENAMEL CAN BE LOST BY:3,4
• Physical mechanism• Abrasion (mechanical wear)• Attrition (tooth-to-tooth contact)
• ABFRACTION (LESIONS)• Chemical dissolution • Erosion by extrinsic acids (from diet)• Erosion by intrinsic acids (from the oral
cavity/digestive tract)
• MULTIFACTORIAL ETIOLOGY• Combination of physical and chemical factors
•Softer than enamel
•Susceptible to tooth wear
(physical or chemical)
•Does not have a nerve supply
but can be sensitive
•Is produced throughout life
•Will demineralize at a pH of 6.5
and lower
DENTAL TISSUES—DENTIN2
•Three
classifications
•Primary
•Secondary
•Tertiary
THREE CLASSIFICATIONS:
•PRIMARY DENTIN forms the initial shape of the tooth.
•SECONDARY DENTIN is deposited after the formation of the primary dentin on all internal aspects of the pulp cavity.
•TERTIARY DENTIN, or “reparative dentin” is formed by replacement odontoblasts in response to moderate-level irritants such as attrition, abrasion, erosion, trauma, moderate-rate dental caries, and some operative procedures.
DENTAL TISSUES—DENTIN2
TYPES OF DENTIN
Dentin
Primary physiologic dentin
Secondary physiologic dentin
Tertiary dentin orreparative dentin orreactionary dentin or
irregular secondary dentin
Mantle dentin
Circumpulpal dentin
Peritubular dentin
Intertubular dentin
Dentin
Pulp
Tubule
Fluid Nerve Fibers
Odontoblast Cell
•DENTINAL TUBULES connect the dentin and the pulp (innermost part of the tooth, circumscribed by the dentin and lined with a layer of odontoblast cells)
•The tubules run parallel to each other in an S-SHAPE COURSE
•Tubules contain FLUID AND NERVE FIBERS
•External stimuli cause movement of the dentinal fluid, a hydrodynamic movement, which can result in short, sharp pain episodes
DENTAL TISSUES—DENTIN (TUBULES)2
•Presence of tubules renders dentin permeable to fluoride
•Number of tubules per unit area varies depending on the location because of the decreasing area of the dentin surfaces in the pulpal direction
ASSOCIATION BETWEEN EROSION AND DENTIN HYPERSENSITIVITY3
• Open/patent tubules
– Greater in number
– Larger in diameter• Removal of smear layer• Erosion/tooth wear
Enamel
ExposedDentin
RecedingGingiva
Tubules
Odontoblast
ORAL ANATOMY AND PHYSIOLOGY
•Thin layer of mineralized tissue covering the dentin
•Softer than enamel and dentin
•Anchors the tooth to the alveolar bone along with the periodontal ligament
•Not sensitive
DENTAL TISSUE—CEMENTUM2
• The Pulp is a soft MESENCHYMAL CONNECTIVE TISSUE
that occupies pulp cavity in the central part of the teeth.
• It is a special organ because of the unique environment
• DENTAL TISSUE—DENTAL PULP2
*THE CORONAL PULP: it is present in the
pulp chamber. *THE RADICULAR
PULP: it is that part of the
pulp extending from the cervical region of the crown to the root apex.
*APICAL FORAMEN: The pulp organs are
continuous with the periapical tissue through the apical foramen.
MORPHLOGY
They are commonly seen to extend from the radicular pulp latrally through the root dentin to the periodontal ligament.
They are numerous in the apical third of the root.
Accessory canals
ACCESSORY CANALS:
CORONAL PULP
• It is the pulp occupying the pulp
chamber of the crown of the
tooth
• In young teeth it resembles the
shape of the OUTER DENTIN
• IT HAS SIX SURFACES : occlusal,
mesial, distal, buccal, lingual
and floor.
• PULP HORNS are projections
into the cusp
• THIS PULP CONSTRICTS at the
cervical region where it
continues as the radicular pulp
RADICULAR PULP
• It is the pulp occupying the pulp canals of the ROOT OF THE TOOTH
• In the anterior tooth it is SINGLE and in the posterior teeth it is MULTIPLE
• The radicular portions of the pulp is CONTINUOUS with the periapical tissues through apical foramen
• As AGE advances the width of the radicular pulp is reduced, and so is the apical foramen. www.rxdentistry.blogspot.com
APICAL FORAMEN
• Pulp cavity terminates at root
apex as small opening called
APICAL FORAMEN
• RADICULAR PULP continuous
with connective tissue of the
PERIODONTIUM through this
foramen.
• WIDE OPEN during
development of root
• Sometimes apical opening is
found on the LATERAL SIDE OF
THE APEX
• There may be 2-3 foramina
split by cementum or dentin-
APICAL DELTA
ACCESSORY CANAL
• Leading LATERALLY from the radicular pulp into the periodontal tissue.
• Present in the APICAL THIRD of the root sheath cells
• Formed due to premature loss of HERS or when developing root encounters a blood vessel.
• Overall occurrence is 33%
• May also be present at the FURCATION REGION
FUNCTIONS OF THE DENTAL PULP
NUTRITION: blood supply for pulp and dentin.
SENSORY: changes in temp., vibration and
chemical that affect the dentin and pulp.
FORMATIVE: the pulp involve in the support,
maintenance and continued formation of
dentin. (dentinogenesis)
PROTECTIVE: Development and formation of
secondary and tertiary dentin which increase
the coverage of the pulp.
• First line of defense to injuries and infection of dentine• Tertiary dentine• Immuno-competent• Clearance of toxic substances
DEFENSIVE: triggering of
inflammatory and immune
response.
DENTIN_PULP COMPLEX
Dentin and pulp are
embryologically,
histologically, and
functionally the same
tissue and therefore are
considered as a complex
Both dentin and pulp
have a common origin
from the dental papilla.
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