Lecture 2

Teeth & Investing Tissues:

Teeth & Investing Tissues:

Dentition

Classes if Human Teeth

Physiology of Tooth Forms

Structures of the Teeth

Dentition

Term that describes all of the upper and lower teeth collectively.

Arches

The teeth are normally arranged in the maxillary and mandibular arches

Quadrants

Each half of the arch

Each arch can be divided in half by an imaginary vertical line (Midline)

Primary Dentition

Also called baby, milk, lacteal teeth

Consist of 20 teeth in all; (10 upper & 10 lower teeth)

Begin to merge about 6 months of age and is completed around 2 – 3years old.

Permanent Dentition

Composed of 32 teeth in all (16 upper & 16 lower teeth)

Emerged at 6 years of age and gradually replace the smaller primary/deciduous teeth

Eruption process is completed by 12-13 years EXCEPT the four 3rd molars which erupt around 18-25 years of age.

Classes of Teeth

Incisors

Canines

Premolars

Molars

Incisors

Cutting or shearing instrument

Canines

Seizing, piercing, & tearing of food as well as in cutting.

Premolars

Dual role: like Canines in tearing of food; like Molars in the grinding of food

Molars

Crushing, grinding & chewing of food to the smallest dimensions suitable for deglutition

Dental Notation

PALMER’s Notation System

UNIVERSAL Numbering System (adopt by ADA)

FDI System / ISO – Two digit system

Palmer’s Notation System

Permanent - Quadrant Sign and Number 1-8

Deciduous - Quadrant Sign and Letters A-E

Universal Numbering System

Permanent Teeth - Denoted by numbers 1 through 32

Deciduous - Denoted by A to T

Two Digit System/Federation Dentaire Internationale (FDI)/International Organization for Standardization (ISO)

Each tooth (permanent/deciduous) is given a two-digit number

The first digit indicates the quadrant and whether the tooth is permanent or deciduous.

PERMANENT DENTITION

#1 – maxillary right quadrant

#2 – maxillary left quadrant

#3 – mandibular left quadrant

#4 – mandibular right quadrant

The second digit identifies the particular tooth in the quadrant (1-8)

DECIDUOUS DENTITION

The first digit indicates the quadrant

#5 – maxillary right quadrant

#6 – maxillary left quadrant

#7 – mandibular left quadrant

#8 – mandibular right quadrant

The second digit identifies the particular toot in the quadrant (1-5)

Labial Surface

Lingual Surface

Mesial Surface

Distal Surface

Incisal Surface

SURFACES OF TEETH

Anterior Teeth

Buccal Surface

Lingual/Palatal Surface

Mesial Surface

Distal Surface

Occlusal Surface

SURFACES OF TEETH

Posterior Teeth

Labial Surface

In the incisors & canines, the surfaces towards the lips

Occlusal Surface

Broad chewing surface of the posterior.

Incisal Surface

Narrow cutting surface of the anterior teeth.

Proximal Surface

Surfaces of the teeth facing toward adjoining teeth in the same dental arch

Mesial

Towards the midline

Distal

Away from the midline

Mesiodistally

Faciolingually: Labiolingual(anterior); buccolingual (posterior)

Cervicoincisally (anterior)/ Cervico-occlusally (posterior)

Divisions of Crown

MESIAL third

MIDDLE third

DISTAL third

Mesiodistally

INCISAL (anterior) / OCCLUSAL (posterior) third

MIDDLE third

CERVICAL third

Cervico-occlusal/Cervicoincisally

LABIAL or BUCCAL third

MIDDLE third

LINGUAL third

Faciolingually

CERVICAL third

MIDDLE third

APICAL third

Divisions of the Root

Line Angle

Formed by the junction of two surfaces

LABIOINCISAL

MESIOLINGUAL

MESIOLABIAL

LINGUOINCISAL

DISTOLINGUAL

DISTOLABIAL

Anterior Line Angles

MESIO-OCCLUSAL

MESIOBUCCAL

BUCCO-OCCLUSAL

MESIOLINGUAL

LINGUO-OCCLUSAL

DISTOLINGUAL

DISTO-OCCLUSAL

DISTOBUCCAL

Posterior Line Angles

Point Angle

Formed by the junction of three surfaces

MESIOLABIOINCISAL

DISTOLABIOINCISAL

MESIOLINGUOINCISAL

DISTOLINUOINCISAL

Anterior Point Angles

MESIOLINGUO-OCCLUSAL

MESIOBUCCO-OCCLUSAL

DISTOLINGUO-OCCLUSAL

DISTOBUCCO-OCCLUSAL

Posterior Point Angles

Anatomic Landmarks on Tooth Surface

Functions of Teeth

Mastication

Esthetics

Speech

Protection of supporting tissues

Height of contour (crest of curvature)

Is the greatest area of contour on the facial and lingual surfaces.

Convexity

Located at the cervical third of the crown on the facial surfaces of all teeth & the lingual surfaces of incisors and canines.

Middle third of the crown.

Where is the lingual surfaces of the posterior teeth usually have their height of contour?

Curvatures are too great

The tissues usually receive inadequate stimulation by the passage of the food.

Too little contour

May result in trauma to the attachment apparatus.

Contacts with the proximal surfaces of the adjacent teeth which prevents food impaction.

Adequate embrasure space gingivally for the gingival tissue, supporting bone, blood vessels and nerves that serve the supporting structures.

Proper proximal height of contour serves to provide:

Proximal contact areas

Areas on the surfaces of the teeth where the proximal surfaces touch one another.

Point Contact

It is seen in young persons with newly erupted teeth.

Contact area

It is formed due to wear of proximal surface against another during physiologic tooth movement.

Incisal third

Where is the proximal contact of maxillary and mandibular incisors located?

Incisal/occlusal thirds and middle thirds

Where is the contact area of the remaining teeth going posteriorly located?

Stabilize the dental arches by combined anchorage effect of all the teeth

Serves to keep food away from packing between the teeth

Protect interdental papillae.

Importance of proper contact relation:

Embrasures

open space; Spillways

V-shaped spaces that originate at the proximal contact areas between adjacent teeth

FACIAL (buccal or labial)

LINGUAL

INCISAL or OCCLUSAL

GINGIVAL

Name for the location of Embrasures

Gingival embrasure

What does the interdental papilla fill?

Col

(Valley) central faciolingual concave area beneath the contact

Vulnerable to periodontal disease from incorrect contact and embrasure form because it is covered by nonkeratinized epithelium.

FALSE. They are larger

TRUE OR FALSE. Are lingual embrasure smaller than facial embrasures?

Triangular

In faciolingual section, interdental papila between anterior teeth is shaped as

Mountain range

In faciolingual section, interdental papila between posterior teeth is shaped as

TRUE

TRUE OR FALSE. The lingual embrasure is usually larger than the facial to allow more food to be displaced lingually

FALSE. It should be the same

TRUE OR FALSE. The marginal ridges of the adjacent posterior teeth should be at the different height to have proper contact and embrasure forms

TRUE

TRUE OR FALSE. Correct anatomic form renders the teeth more self-cleansing.

Correct relationships of embrasures, marginal ridge contours, grooves of adjacent and opposing teeth provide escape of food from occlusal surfaces during mastication.

If embrasure size is decreased / absent, then additional forces are created in the teeth and supporting tissues during mastication.

If embrasure size is enlarged, food impaction occurs in interproximal space by opposing cusp, resulting in damage to supporting tissues.

Significance of Embrasures