tooth surfaces & thirds

الله بسمالرحمن الرحيم

Anatomy of the Tooth. Tissues of the tooth. Types of Dentition/teeth. Dental Formula. Tooth Numbering Systems. Tooth Morphology. Significance of tooth

morphology. Tooth Relationship with

each others.

Objectives. .

Objectives Dental Formula. Tooth Numbering Systems. Tooth Morphology. Significance of tooth morphology. Tooth Relationship with each

others. Prof. Dr. Naglaa Bahgat

Nagy

. .

DENTAL FORMULA.

Dental arches (Maxillary &

Mandibular).

Jaw quadrants (There are four

quadrants) .

Half of the mouth (Right & left

halves).

Teeth are arranged in two arches: (Dental Arches)

-An Upper Arch or the Maxillary arch.

A Lower arch or the Mandibular arch.

Each dental arch has a Midline that divides the arch Into two approximately equal segments or Quadrant. (Right & Left )

Thus, there are Four Quadrants in the entire oral cavity.

Dental arches Teeth are arranged in two arches:- Upper [maxillary] & lower [mandibular]

arches. The teeth in the upper arch might not be

similar to those in the lower arch.

Jaw Quadrants An imaginary midline divides each arch into

two equal halves (a left half and a right half). Thus, the maxillary and mandibular arches

are each divided into two halves the resulting four sections are called quadrants, as follows:

1. Maxillary right quadrant.2. Maxillary left quadrant.3. Mandibular right quadrant.4. Mandibular left quadrant.

Half of the mouth The mouth could be divided into two

equal halves (right & left). Thus, each half contains the same

number and types of teeth. The formula which describes teeth in half

of the mouth is called dental formula.

DENTAL FORMULA It is a shorthand way to indicate the type

and number of teeth in half of the mouth in any mammals.

The denomination (type) of each tooth is represented by its initial letter (I, C, P, M).

Each letter is followed by a horizontal line.

The number of each type of teeth is placed above the line for the maxillary teeth and below the line for the mandibular teeth.

Dental formula for human Human has two sets of dentition

(diphyodont). The dental formula for deciduous teeth is: I ----- C ------ M -------- =10 Thus, the child has 20 deciduous teeth.

The dental formula for permanent teeth is:

I ----- C ------ P ------ M ------- = 16 Thus, the adult person has 32 teeth.

Dental formula for sheep & dogs

Numbering Systems

Numbering Systems

Numbering systems have

been developed in order to have a

standard way of referring to particular

teeth.

Numbering Systems

Universal Numbering System.

Palmer Notation System.

Federation Dentaire Internationale (FDI).

Universal Numbering System. It assumes the two arches (upper & lower) form a

circle. It assigns a specific number to each permanent tooth

(one through thirty-two). It assigns a specific capital letter to each deciduous

tooth (A through T). The numbering system starts from the last right

maxillary tooth, going clockwise. The permanent right maxillary third molar is

designated as tooth #1 and the permanent right maxillary central incisor #8.

The deciduous right maxillary second molar is designated as tooth #A and the deciduous right maxillary central incisor #E.

Universal System for Permanent Teeth.

Universal System for Deciduous Teeth

Universal Numbering System.

Advantage: It is acceptable to the computer

language.

Disadvantage: It doesn’t consider the jaw

quadrant clearly. Thus, similar teeth are given various numbers in different quadrants.

It uses the quadrant system. It divides the maxillary and mandibular arches

into two quadrants (right and left). It identifies each quadrant by a symbol.

┘for right maxillary quadrant. └ for left maxillary quadrant. ┐for right mandibular quadrant. ┌ for left mandibular quadrant.

Permanent teeth are identified by number, one through eight, in each quadrant.

Deciduous teeth are identified by capital letters, A, B, C, D, E, in each quadrant..

The numbering system starts from the midline and goes backwards.

Palmer Notation System:

└

Palmer Notation System forPermanent teeth

Right

8 7 6 5 4 3 2 1

8 7 6 5 4 3 2 1

Left

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

Palmer Notation System forDeciduous teeth

Right

E D C B A

E D C B A

Left

A B C D E

A B C D E

Palmer Notation System

Advantage: Simple and easy in clinical practice.

Disadvantage: Ii is not acceptable to the computer

language.

Federation Dentaire Internationale

(FDI)

Federation Dentaire Internationale (FDI) It is a two-digit system. (1). The first digit indicates the quadrant: Quadrants for permanent teeth are given number one through

four. Quadrants for deciduous teeth are given number five through

eight. The quadrant numbering starts from the right maxillary quadrant

and goes clockwise. Thus, for permanent dentition, the quadrants number are:

The right maxillary quadrant is #1. The left maxillary quadrant is #2. The right mandibular quadrant is #3. The left mandibular quadrant is #4.

For deciduous dentition, the quadrants number are: The right maxillary quadrant is #5. The left maxillary quadrant is #6. The right mandibular quadrant is #7. The left mandibular quadrant is #8.

Federation Dentaire Internationale (FDI) It is a two-digit system.

(2). The second digit indicates the tooth. Both permanent and deciduous teeth are identified by numbers.

Tooth numbering uses the quadrant system.

It starts from the midline and goes backwards (for each quadrant).

Permanent teeth are identified by numbers, one through eight.

Deciduous teeth are identified by numbers, one through five.

The tooth number is written next to the quadrant number.

FDI System for Permanent Teeth

FDI System for Deciduous Teeth

Federation Dentaire Internationale (FDI)

Advantage: It is acceptable to the computer

language.

Disadvantage: It is somewhat confusing.

Objectives Anatomy of the Tooth. Tissues of the tooth. Types of Dentition/teeth. Dental Formula. Tooth Numbering Systems. Tooth Morphology. Significance of tooth

morphology. Tooth Relationship with each

others.

. .

TOOTH MORPHOLOGY

Tooth Morphology

Tooth Surfaces. Division into Thirds. Line angles and point angles. Crown Elevations & Depressions.

Tooth Morphology

Tooth Surfaces

Adult has Four Types of Teeth:

Anterior teeth which include:1-Incisors: In each arch there are four incisors (two

central incisors and two lateral incisors).

2-Canines: There is one canine in each quadrant.

Posterior teeth which include: 3-Premolars: There are two in each quadrant. First and

second premolars.

4-Molars: There are three in each quadrant. They are

the first molar, the second molar and the third molar.

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4

Tooth surfaces

Facial

Proximal

Cutting

Tooth Surfaces Facial Surfaces:

Labial/Buccal. Lingual/Palatal.

Proximal Surfaces: Mesial. Distal.

Cutting Surfaces: Incisal. Occlusal.

Upper (Maxillary) Arch

Labial/BuccalSurface

PalatalSurface

Occlusal Surface

Incisal Surface

Lower (Mandibular) Arch

Buccal Surface

LingualSurface

OcclusalSurface

IncisalSurface

Mesial surface – towards the front of the mouth

Distal surface – towards the back of the mouth

Midline

Tooth Surfaces

Thus, each tooth has five surfaces, which are named according to their relative position to the middle line, the surrounding tissues or to their functions.

Tooth Surfaces

Division into thirds For descriptive purpose: Each surface of both crown and root

could be arbitrary divided horizontally and vertically into three thirds.

Thirds are named according to their location in relation to other surfaces of the tooth.

Division into thirds

(1). Horizontally:Cervico -occlusally/ -

apically Crown has incisal (occlusal), middle and

cervical thirds. Root has apical, middle and cervical

thirds.

Horizontal thirds of the Crown :

Incisal (Occlusal) third

Middle third

Cervical third

Horizontal thirds of the Root

Apical third

Middle third

Cervical third

Division into thirds

(1). Vertically:First: Bucco- (Labio) -lingually

(Palatally). Crown has mesial, middle and distal

thirds. Second: Mesio- distally. Crown has buccal (labial), middle and

lingual (palatal) thirds.

Vertical bucco-lingual thirds of the Crown :

Mid

dle

thir

d

Mes

ial t

hird

Dis

tal t

hird

Vertical mesio-distal thirds of the Crown :

Mid

dle

thir

d

Bucc

al (

Labi

al)

thir

d

Ling

ual

(pal

atal

) th

ird

Line angles & point angles Line angle:

• It is the junction between any two surfaces.

Point angle:• It is the junction between any three surfaces.

Name Line

angles and point angles in this figure?

Structural Features:

Crown Elevations.

Crown Depressions.

This will be given by Prof. Dr. Amal Radawn

Thank you