tooth morphology basics

Tooth Morphology Basics

Howard Chi, D.M.D.

Learning Objectives

• Primary and permanent dentition• Tooth identification system• Trait categories• Tissues of the tooth• Dental terminology• Anatomy of tooth structure

Primary and Permanent Dentition

Dentition

Refers to all of the teeth in the maxillae and the mandible

* maxillary arch - maxillary teeth* mandibular arch - mandibular teeth

Maxillary arch

Mandibular arch

Humans Have Two Dentitions Throughout Life

1) Primary Dentition - during childhood2) Permanent Dentition - during adulthood

PrimaryPermanent

Primary Dentition

• There are 20 teeth in the primary dentition• 10 maxillary - 10 mandibular• This dentition is also termed the deciduous

dentition

Permanent 1st Molars

Primary Dentition

The dental formula for one side of the mouth is:I 2 C 1 M 2 = 10 teeth on either side 2 1 2

11 212

11 212

Deciduous Teeth

Those teeth that “fall out” due to a natural process of tooth succession

Permanent Dentition

Also called the succedaneous dentition - that which succeeds the primary dentition

There are 8 teeth in each quadrant

I 2 C 1 PM 2 M 3 = 16 teeth 2 1 2 3 each side

Permanent Dentition

First signs of this dentition appear at age 6

Permanent Dentition

A A A P P P P P

Anterior Teeth - incisors and caninesPosterior teeth - premolars and molars

Tooth Identification Systems

Tooth Identification Systems

There are three main systems used in modern dentistry for the numbering of teeth. They are:

* Universal Numbering System* Palmer Notation System* International Numbering System

Universal Numbering System

1. Suggested by Parreidt in 18822. Adopted by the A.D.A. in 19753. Uses numbers 1 through 32


1 for upper right third molar around to 16upper left third molar

1 16

Dropping down same side to 17 lower leftthird molar and around to 32


1732

For deciduous dentition, letters A through T are used


A B C D E F G H I J

T S R Q P O N M L K

Universal Numbering

System

Palmer Notation System

Utilizes brackets to represent the four quadrants

Upper Right Upper Left

Lower Right Lower Left

• Permanent teeth are labeled 1 to 8 on each side of the midline

• On deciduous teeth same brackets with letters A through E

Palmer Notation System

Palmer System

International Numbering System

• Uses two digits for each tooth• First digit represents dentition, arch and

side• Second number denotes the tooth (1-4

perm. and 5-8 prim.)


1 = permanent dentition, maxillary, right2 = permanent dentition, maxillary, left3 = permanent dentition, mandibular, left4 = permanent dentition, mandibular, right5 = primary dentition, maxillary, right6 = primary dentition, maxillary, left7 = primary dentition, mandibular, left8 = primary dentition, mandibular, right

Trait Categories

Trait Categories

Set Traits: (dentition traits) distinguish teeth in the primary from secondary dentition

Trait Categories

Arch Traits: distinguish maxillary

from mandibular

Trait Categories

Class Traits: Distinguish the four categories of teeth ... incisors, canines, premolars, molars

Trait Categories

Type Traits: Distinguish teeth within one class

Tissues of the Tooth

Tissues Of A Tooth

1) Dentin2) Enamel3) Cementum4) Pulp

Enamel

• Makes up the protective outersurface of the anatomic crown

• Mostly inorganic and calcifiedhard, white shiny surface of theanatomic crown

Dentin

• Found in the crown and root, making up bulk of tooth

• Found beneath the enamel and cementum and surrounding the pulp tissue

• Not normally visible• Mostly inorganic and calcified

Cementum

• Makes up the surface of the anatomic root• Very thin next to cervical line• Mostly inorganic calcified• Dull yellow in color

Pulp• Is non calcified found within the pulp chamber• Develops from the dental papilla

(from mesoderm)• Surrounded by dentin except at the

apical foramen

Pulp• Normally not visible except on

dental radiographs• In the coronal portion termed

the pulp chamber• In the root portion termed the

pulp canal(s)

Pulp - Functions

• Formative - dentin producing cells (odontoblasts) produce dentin thoughout the life of a tooth

• Sensory - nerve endings permit the sense of pain

Pulp - Functions

• Nutritive - nutrient transport from the blood stream to extensions of the pulp that reach into dentin

• Defensive/Protective - responds to injury and decay by forming reparative dentin

Junctions Of Tooth Structure

Cementoenamel Junction - also called the cervical line, separates the anatomic crown from the anatomic root.


Dentinoenamel Junction - is the inner surface of the enamel cap visible in cross section or in badly worn teeth


Cementodentinal Junction - a.k.a. dentinocemental junction is the inner surface of cementum lining the root visible in cross section or badly worn teeth

Anatomic Versus Clinical Crown

Anatomic Crown - that part of the tooth covered in enamel

Clinical Crown - that part of the tooth that is visible in the oral cavity

Dental Terminology

Terminology Used To Distinguish Tooth Surfaces

Facial Surface - the surface next to the face, the outer surface of a tooth resting next to the cheeks or gums. Used in both anterior and posterior teeth


Buccal Surface - the facial surface of posterior teeth. Meaning next to the cheek


Labial Surface - the facial surface next to the lips, generally used for anterior teeth


Proximal Surface - the surface or side of a tooth that is next to an adjacent tooth, not considered self-cleansing

Mesial Surface - is the surface of the tooth nearest to the midline of the dental arch


Distal Surface - is the surface of the tooth farthest from the midline of the dental arch



Lingual Surface - is the surface of maxillary and mandibular teeth nearest the tongue


Palatal Surface – is the surface of

maxillary teeth nearest the palate


Occlusal Surface - is the chewing surface of the posterior teeth found within cusp and marginal ridges


Incisal Edge - is the cutting edge, ridge or surface of anterior teeth

Anatomy of Tooth Structure

Divisions Of The Crown And Root Of A Tooth

Divisions Cervico-occlusally

Cervical 3rdMiddle 3rdIncisal 3rd

Cervical 3rdMiddle 3rdOcclusal 3rd

Anterior Posterior

Divisions Of The Crown Of A Tooth

Divisions Mesiodistally

Distal 3rd

Middle 3rd

Mesial 3rd

Divsions Of The Crown Of A Tooth

Divisions Faciolingually

Lingual 3rd

Middle 3rd

Facial 3rd

Divisions Of The Crown And Root Of A Tooth

Divisions Cervico-occlusally

Apical 3rdMiddle 3rdCervical 3rdCervical 3rdMiddle 3rdIncisal 3rd

Apical 3rdMiddle 3rdCervical 3rdCervical 3rdMiddle 3rdOcclusal 3rd

Anterior Posterior

Morphology Of An Anatomic Crown

Cusp - is a point, or peak on the chewing surface of premolar or molar tooth


Cusp Slopes Or Ridges - are the inclined surfaces that form an angle at the cusp tip

How Many Cusp Ridges Does This Tooth Possess?


Cingulum - is the enlargement or bulge on the cervical third of the lingual surface of the crown of anterior teeth


Labial Ridge - is a ridge running cervico-incisally in approximately the center of the labial surface of the canines


Buccal Ridge - is the ridge running cervico-occlusally in approximately the center of the buccal surface of premolars


Cervical Ridge - ridge running mesiodistally on the cervical one-third of the buccal surface of the crown, found on all deciduous teeth but only on the permanent molars


Marginal Ridge - on incisor and canine located on the mesial and distal border of the lingual surface


Marginal Ridge - on posterior teeth located on the mesial and distal border of the occlusal surface


Triangular Ridge - on the occlusal surface of posterior teeth, is the ridge from any cusp tip to center of the occlusal surface - ML cusp of upper molars have two


Oblique Ridge - found only on maxillary molars made of the triangular ridges of the mesiolingual and distobuccal cusps

Transverse Ridge - ridge crossing the occlusal surface of posterior teeth in a B-L direction and made of connecting triangular ridges



Mamelon - is one of three tubercules sometimes present on the incisal edge of an incisor tooth that has not been subject to wear


Sulcus - is a broad depression or valley on the occlusal surface of posterior teeth


Developmental Groove - is a sharply defined, narrow and linear depression, formed during tooth development separating lobes or a major portion of a tooth - a fissure may be found at the depth of a developmental groove


Supplemental Groove - small irregularly placed grooves not at the junction of lobes or major portions of the teeth


Fossa - a depression or hollow found on the lingual surfaces of some anterior teeth and on the occlusal surfaces of posterior teeth


Pits - often occur at the depths of fossa where two or more grooves join


Furcation - is the place on multirooted teeth where the root trunk or base divides into separate roots

RootTrunk

Curve Of Spee

Anteroposterior curve of the occlusal plane - curve of the maxillary arch is convex

Curve Of Wilson

Gradual curve of posterior teeth from left to right side viewed from the anterior region - curve of maxillary teeth is convex

tooth morphology basics

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