Normal Occlusion

Line of Occlusion (Upper)

a smooth (catenary) curve passing through the central fossa of each upper molar and across the cingulum of upper canine and incisor teeth

Line of Occlusion (Upper)

Line of Occlusion (Upper): a smooth (catenary) curve passing through the ______ of each upper molar and across the cingulum of ________.

central fossa ; upper canine and incisor teeth

Normal Occlusion

Class I Malocclusion

smooth (catenary) curve that runs along the buccal cusps and incisal edges of the lower teeth

Line of Occlusion (Lower)

Line of Occlusion (Lower): smooth (catenary) curve that runs along the _____ and incisal edges of the _____.

buccal cusps ; lower teeth

Line of Occlusion (Lower)

The perfect occlusion

Ideal Occlusion

Occlusion that never attained in nature

Ideal Occlusion

hypothetical goal for orthodontists

Ideal Occlusion

6 KEYS TO NORMAL OCCLUSION

1. Molar Relationship

2. Crown Angulation

3. Crown Inclination

4. Rotations

5. Spacing

6. Occlusal Plane

Impropert Molar Relationship

Improved Molar Relationship

More Improved Molar Relationship

MBC of U6 occludes in the groove between mesial and middle cusps of L6

Propert Molar Relationship

Distal surface of DBC of U6 occludes with the mesial surface of MBC of L7

Proper Molar Relationship

He used 120 ortho cases with normal occlusions, that’s how he formulated the 6 keys to normal occlusion

Lawrence Andrews

How many cases did Lawrence Andrews used to arrive at the 6 keys to normal occlusion

120

long axis of the clinical crown (LACC)

Vertical line

center of long axis of clinical crown (LACC)

LA spot

mesiodistal tip

Crown Angulation

gingival portion of LACC is distal to the incisal portion

Crown Angulation

expressed in degrees (+ or -)

Crown Angulation

Give the reading: gingival portion of LACC is distal to the incisal portion

+ Reading

Give the reading: gingival portion of the LACC is mesial to the incisal portion

- Reading

Crown Angulation

the degree of angulation depends on the ______

type of tooth

line passing through LA spots

horizontal plane reference

perpendicular to the horizontal plane

vertical plane reference

labiolingual or buccolingual inclination of LACC

Crown Incliantion

expressed as + or - degrees

Crown Inclination

What does the degrees in crown inclination represent

the angle formedby the line which is 90° to OP and a line tangent to the bracket site

Give the reading for crown inclination: gingival portion of the tangent line or of the crown is lingual to the incisal portion

+ Reading

Give the reading for crown inclination: gingival portion of the tangent line or of the crown is labial to the incisal portion

- Reading

Improperly inclined anterior crowns results in ___________

upper contact points being mesial

Properly inclined anterior crowns, contact points move ____

distally

spaces resulting from normally occluded posterior teeth and insufficiently inclined anterior teeth are often blamed on _______

tooth size discrepancy

for upper canine through molars lingual crown inclination in upper posterior teeth

CROWN INCLINATION Upper Posterior Teeth

constant/similar from canine thru second premolars

CROWN INCLINATION Upper Posterior Teeth

slightly more pronounced in molars

CROWN INCLINATION Upper Posterior Teeth

for lower canine through molars

CROWN INCLINATION Lower Posterior Teeth

lingual inclination progressively increases from canines through second molars

CROWN INCLINATION Lower Posterior Teeth

rotated premolars/molars = _________

occupy more space in the arch

contacts points are tight

Spacing

flat occlusal plane to slight curve of Spee

OCCLUSAL PLANE

_______ is best when occlusal plane is flat

intercuspation

results in more contained area for upper teeth, making normal occlusion impossible

Deep Curve of Spee

allows excessive space for each tooth to be intercuspally placed

Reverse Curve of Spee

contact of a tooth or teeth along the retruded path of closure

RETRUDED CONTACT POSITION (RCP)

initial contact of a tooth or teeth during closure around a transverse horizontal axis

RETRUDED CONTACT POSITION (RCP)

maximal intercuspal position (MIP)

INTERCUSPAL POSITION (ICP)

the complete intercuspation of opposing teeth independent of condylar position

INTERCUSPAL POSITION (ICP)

the best fit of the teeth regardless of condylar position

INTERCUSPAL POSITION (ICP)

a maxillo-mandibular relationship independent of tooth contact

CENTRIC RELATION (CR)

the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminence

CENTRIC RELATION (CR)

the occlusion of opposing teeth when the mandible is in centric relation

CENTRIC OCCLUSION

Centric Relation but not in centric occlusion

Centric occlusion but not in centric relation

CR = CO

CR to CO Slide

CR to MIP

a form of mutually protected articulation

CANINE GUIDANCE

horizontal and vertical overlap of canine teeth disclude the posterior teeth in the excursive mov’t of mandible

CANINE GUIDANCE

multiple contact relations between the maxillary and mandibular teeth in lateral movements on the working- side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces

Group Function

Group Function: multiple contact relations between the ______ in lateral movements on the working-side whereby simultaneous contact of several teeth acts as a group to distribute ______

maxillary and mandibular teeth ; occlusal forces

an occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximal intercuspal position, and the anterior teeth disengage the posterior teeth in all mandibular excursive movements.

MUTUALLY PROTECTED ARTICULATION

Teeth of the anterior and posterior dentitions protect each other during function

MUTUALLY PROTECTED ARTICULATION

MUTUALLY PROTECTED ARTICULATION:

an occlusal scheme in which the ______ prevent excessive contact of the anterior teeth in maximal intercuspal position, and the _____ disengage the posterior teeth in all mandibular excursive movements.

posterior teeth ; anterior teeth

CANINE GUIDANCE: horizontal and vertical overlap of ______ disclude the _____ in the excursive mov’t of mandible

canine teeth ; posterior teeth