OCCLUSION

Eruption (Primary Teeth)

Movement of tooth toward the occlusal plane

Eruption (Primary Teeth)

Does not occur until root formation has begun

Eruption (Primary Teeth)

No significant sexual differences in primary tooth emergence

Eruption (Primary Teeth)

Develops independently of other morphologic process

Occlusion (Primary Teeth)

Interdentation occurs sequentially beginning in the front as the incisors erupt

Occlusion (Primary Teeth)

Muscles learn to effect the necessary functional occlusal movements

Occlusion (Primary Teeth)

Less variability in occlusal relationship in the primary than in the permanent dentition

Occlusion (Primary Teeth)

Primary occlusion is established during more labile periods of mental adaptation

Generalized interdental spacing

Physiologic and desirable

Generalized interdental spacing

Aids in accommodation of larger successor teeth

Primary spaces

AKA “Primate or Anthropoid or Simian” spaces

Primary spaces

Wider spaces found mesial to the maxillary cuspids and distal to the mandibular cuspids

Minimal overbite and overjet

Normal feature of the deciduous dentition

Minimal overbite and overjet

Due to the fact that the primary incisors are more vertically placed than the permanent

Mixed dentition stage

Spans from 6 - 12 years of age

Mixed dentition stage

Transition stage wherein primary teeth are exfoliated followed by eruption of their permanent successors

Mixed dentition stage

Begins with the eruption of the first permanent tooth and completed when the last primary tooth is shed

Mixed dentition stage

Most malocclusions are developed in this stage

Early stage or 1st transitional period

6 to 8 years

Early stage or 1st transitional period

Replacement of primary incisors

Early stage or 1st transitional period

Addition of first 4 permanent molars

Inter-transitional period

Interim period of 1 to 2 years before the 2nd period

Inter-transitional period

Relatively stable phase with minor changes

Late or 2nd transitional period

Replacement of molars and canines by the premolars and permanent canines respectively

Early mesial shift

Utilization of physiologic spaces between primary incisors and primate spaces

Early mesial shift

Eruption forces of the permanent molars push the primary forward into the spaces thereby establishing the Class I molar relationship

Early mesial shift

This change occurs in the early mixed dentition

Late mesial shift

In case of primate space deficiency, class I molar relationship can be achieved in late mixed dentition period following exfoliation of primary second molar, utilizing the Leeway space

Leeway space

Excessive leeway space is favorable for providing the mesial movement of permanent molars

Leeway space

Greater in the mandibular than in the maxillary

Ugly duckling stage

A transient malocclusion observed during 8 to 12 years of age corresponds to eruption of permanent maxillary canines and resolves after their complete eruption

Ugly duckling stage

It requires no treatment

Permanent dentition

Pretty well established by the age of 13 with the eruption of all permanent molars except the third molars

Permanent dentition

Permanent incisors develop lingual to the primary incisors and move labially as they erupt

Permanent dentition

The molars develop below the divergent roots of the primary molars

Permanent dentition

Begins to form at birth, at which time, calcification of the first permanent molars becomes evident

Eruption

The developmental process that moves a tooth to its position through the alveolar process into the oral cavity and to occlusion with its agonist

Eruption

Primary tooth resorbs

Eruption

Permanent tooth’s root lengthens

Eruption

Alveolar process increases in height

Eruption

Permanent tooth moves through bone

Occlusion

Occlusion simply means the contact between teeth

Occlusion

It is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest

Occlusion

Dental occlusions varies among individuals according to tooth size and shape, tooth position, timing and sequence of eruption dental arch size and shape and pattern of cranio- facial

Normal occlusion

an occlusion within the accepted deviation of the ideal

Malocclusion

irregularities in the occlusion beyond the accepted range of normal

Andrew’s Six Keys to Normal Occlusion

Class I molar and canine relationship

Andrew’s Six Keys to Normal Occlusion

Correct crown angulation

Andrew’s Six Keys to Normal Occlusion

Correct crown inclination

Andrew’s Six Keys to Normal Occlusion

No rotations

Andrew’s Six Keys to Normal Occlusion

No spacings

Andrew’s Six Keys to Normal Occlusion

Flat curve of Spee

Class 1 molar and canine relationship

The mesiobuccal cusp of the maxillary first molar occludes with the mesiobuccal groove of the lower first molar

Class 1 molar and canine relationship

The mesial cusp of the maxillary cuspid occludes with the distal cusp of the mandibular cuspid

Correct crown angulation

Refers to the angle formed by the lines between the long axis of the clinical crown and a ninety degree line tangent to the occlusal plane

Correct crown angulation

The gingival part of the crown is usually distal to the occlusal part

Correct crown angulation

Also known as crown tipping

Correct crown angulation

Each tooth has its own specific angulation

Correct crown inclination

Refers to the crown labio-lingual inclination of the anterior teeth or the bucco-lingual inclination of the posterior teeth

Correct crown inclination

Also known as torque

Correct crown inclination

Measured by the angle formed between a ninety degree line to the occlusal plane and the line tangent to middle of the labial or buccal clinical crown

No rotations

In normal occlusion, no rotations of teeth should be found in both arches

No rotations

If rotations are found in any arch, it indicates that there is an arch length deficiency

No rotations

The arch form will be asymmetric and the catenary curve will be distorted in a rotated arch

No spacings

In ideal occlusion, the teeth should be within the normal size and in harmony with the opposite arch

No spacings

All the teeth in both arches should have tight contacts in proximal contact areas

No spacings

Dental arches with insufficient inclined anterior teeth and discrepancy in tooth material will have localized spacing

Flat curve of Spee

The Curve of Spee is defined as the curvature of the mandibular occlusal plane beginning at the canine and following the buccal cusps of the posterior teeth, continuing to the terminal molar

Flat curve of Spee

In normal occlusion, the curve of Spee is relatively flat

Flat curve of Spee

A deep curve of Spee manifests a more confined area for mesio-distal dimension of the maxillary teeth, while a reverse curve of Spee shows an excessive room in the maxillary teeth

Flat curve of Spee

As age progresses after the completion of the permanent set of dentition, the curve of Spee deepens progressively

Types of malocclusion

Dental Dysplasia

Types of malocclusion

Skeletal Dysplasia

Types of malocclusion

Skeletal- Dental Dysplasia

Angle’s Classification

Edward Hartley Angle was an American dentist, widely regarded as "the father of American orthodontics"

Class I

Antero-posterior relationship of the maxilla and mandibular molar is correct

Class I type 1

crowded, rotated upper and lower anterior teeth

Class I type 2

protruding spaced anterior teeth “PSEUDO CLASS II”

Class I type 3

Pseudo class III

Class I type 3

Anterior crossbite, involving one or two teeth

Class I type 4

posterior crossbite, unilateral

Class I type 5

posterior loss of space due to drifting of the first molar (mesial drifting)

Class II

MBG of the mandibular molar no longer receives the MBC of the upper but contacts the DB cusps of the maxillary first molar

Class II Division 1

Anterior segment shows supraversion or overeruption of the incisor teeth

Class II Division 1

The arch form of the maxillary denture is approaching that of a V-shaped

Class II Division 1

Narrowing in the PM and canine region

Class II Division 1

Protrusion or labioversion of the maxillary incisors

Class II Division 2

Usually has an exaggerated curve of spee

Class II Division 2

Supraversion of the mandibular incisors

Class II Division 2

The mandibular labial gingival tissue is often traumatized

Class II Division 2

Excessive lingual inclination of the maxillary central with excessive labial inclination of the maxillary lateral incisors

Class II Division 2

Excessive overbite

Class III

Lower incisors are incline excessively to the lingual aspect

Class III

Maxillary arch is constricted

Class III

Arch length is frequently deficient and total tooth irregularities is common

Class III type 1

mesioocclusion, anterior teeth are in edge to edge relationship

Class III type 2

mesioocclusion, overbite and overjet still positive -Maxillary incisors are labial to lower

Class III type 2

There is crowding of the mandibular incisors

Class III type 3

mesioocclusion, upper anteriors are in cross bite

Class III type 3

Maxillary incisors are lingual to lower