occlusion (orthodontics)

8/3/2019 Occlusion (Orthodontics)

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Normal Occlusion

Presented by: Dr Ghulam Rasool


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Occlusion

The way the maxillary & mandibular teetharticulate

It involves the study of the teeth, theirmorphology and angulations, the musclesof mastication, the skeletal structures, theTMJ & the functional jaw movements


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Occlusion

The occlusion is generally considered for

dentition, because rest of the components

effect through dental component

To understand dental occlusion, we need to

understand the features & terminology relatedwith ideal dental occlusion


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Curve Of Occlusion


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Curve of Occlusion

In the maxilla:

It passes through the central fossa of posteriors and

cingulae of anteriors


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Curve of Occlusion

In the mandible

It passes through the buccal cusps of posteriorand incisal edges of anteriors


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Tip / Angulation

Relative mesial or distal angulation of the

crown and the root along the line of occlusion

(e.g; mesial crown tip, same as distal root tip;distal crown tip same as mesial root tip)


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Torque / Inclination

Relative crown and root inclination perpendicular to

the line of occlusion ( e.g; lingual crown torque same

as labial or buccal root torque ; labial orbuccal crowntorque, same as lingual root torque )


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IN-OUT

Faciolingual relationship of the tooth crowns

to

the line of occlusion ( e.g, labial surface ofcrown is

facially or lingually placed )

OFFSET

Rotations described by the position ofmesial

and

distal proximal tooth contacts in relation to

the line of occlusion


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Cusp Height Positioning

Described on the basis of the position of the occlusal

surfaces inciso-gingivally in relation to the occlusal

plane ( e.g; supra-occlusion and infra-occlusion )


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CLINICAL CROWN

The amount of crown visible in late mixed dentitions and

adult dentitions with gingiva that is healthy and

not recessed

FACIAL AXES OF THE CLINICAL CROWN (FACC)

The most prominent portion of the central lobe on each

crowns facial surface & for molars, the buccal groove that

separates the two large facial cusps

FACIAL AXES POINT (FA POINT)

The point on the facial axes that separates the gingival

half from occlusal half of the clinical crown


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Crown Angulation

The angle formed by the FACC and

a line perpendicular

to the occlusal plane It ispositive when occlusal portion

of FACC is mesial to gingival

portion

It isnegativewhen occlusal

portion of FACC is distal to

gingival portion


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Crown Inclination

The angle between a line perpendicular to

the occlusal plane and a line that is parallel

& tangent to the FACC at its mid point

(FA point)

Crown inclination is determined from

proximal aspect

It ispositiveif the occlusal portion of the

crown, tangent line or FACC is facial to its

gingival portion &negativeif lingual


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Andrews Six Keys of Occlusion

KEY I: CORRECT INTERARCH RELATIONSHIP

KEY II: CORRECT MESIODISTAL CROWN ANGULATION

KEY III: CORRECT FACIOLINGUAL CROWN INCLINATION

KEY IV: ABSENCE OF TOOTH ROTATIONS

KEY V: TIGHT CONTACT POINTS

KEY VI: THE DEPTH OF CURVE OF SPEE RANGES FROM A FLAT

PLANE TO A SLIGHTLY CONCAVE SURFACE


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Key I: Correct Interarch Relationship

1) The mesiobuccal cusp of the permanent maxillary first

molar occludes in the mesiobuccal groove of the permanent

mandibular first molar


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key I: Correct Interarch Relationship

2) The distal marginal ridge of the maxillary first molar occludes with the mesial

marginal ridge of the mandibular second molar

OR

The distobuccal cusp of the maxillary

first molar occludes in the embrasure

between mandibular first molar and

second molar


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key I: correct interarch relationship

3) The mesiolingual cusp of the maxillary first molar

occludes in the central fossa of the mandibular

first molar


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4)The buccal cusps of the

maxillary premolars have a

cusp-embrasure (distal)

relationship with the mandibular

premolars


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5)The lingual cusps of the maxillary

premolars have a cusp-fossa (distal

triangular fossa) relationship with

the mandibular pre-molars


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6)The maxillary canine has a cusp-

embrasure relation-

ship with the mandibular canine

and first premolar

(the tip of the cusp is slightly

mesial to embrasure ideally)


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7) The maxillary incisors overlap

mandibular incisors, horizontally and

vertically (overjet & overbite) & the

midlines of the arches match

Overjet = 2-3 mm

Overbite = 1-2 mm


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key II ) Correct Mesiodistal Crown

Angulation

All the crowns have a positive angulation


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key III) Correct Faciolingual Crown

Inclination

The inclination of the maxillary incisor crowns is

generally POSITIVE and gradually becomes NEGATIVE

canine through molars

The inclination of the mandibular crowns is progressively

more NEGATIVE from the incisors through

the second molars


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KEY IV)

ABSENCE OF TOOTH

ROTATIONS

KEY V)

TIGHT CONTACT POINTS


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KEY VI)

The depth of Curve of Spee ranges from a flat plane to a

slightly concave surface (0-2mm) in the lower arch


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KEY VI)

The Curve of Wilson is

convex in the first

premolars, flat in the second

premolars & concave in the

first molar in the upper arch


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Bennett and Mc Laughlins 7th key

Correct tooth size

In practice orthodontically treatedocclusions seldom achieve allocclusal keys.


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OCCLUSION

MALOCCLUSION :Is the misalignment of teeth and jaws, or moresimply, a "bad bite." Malocclusion can cause

number of health and dental problems.

STATIC OCCLUSION :

Refers to contact between teeth when the jawis closed and stationary.
http://en.wikipedia.org/wiki/Malocclusionhttp://en.wikipedia.org/wiki/Malocclusion


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FUNCTIONAL OCCLUSION:

Refers to occlusal contacts made when the jaw ismoving, as with chewing.

Alternative names are cuspid disclusion or canineguidance.

Immediate but gentle disclusion of all posterior teeth onany excursion from intercuspal position(ICP)

Post centric stops protect anterior teeth in ICP.

Canines and incisors protect anterior teeth in ICP.

Anterior teeth protect posterior in occlusion.


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CANINE GUIDED OCCLUSION

Canine protection :

contact only on theworking-side maxillary

and mandibular canines


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Importance of canine guidance

The strategic positioning of the canine in the arch The favorable root anatomy

Presence of a better crown-root proportion

The presence of dense and compact bone around the root,

which better tolerates the occlusal forces compared with themedullar bone of the posterior teeth

The sensorial pulse that activates less muscles when thecanine teeth are in contact than when posterior teethcontact each other.

The achievement of the canine guidance in orthodontics iseasier than the group function. It is because mechanically itis much easier to establish the contact in a single tooth thanto distribute the contacts simultaneously in all the posteriorteeth.


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GROUP FUNCTIONOCCLUSION

Simultaneous contactof the canine andposterior teeth on the

working side.


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Group function must be established

When the canine teeth do not present anappropriate position to accept the horizontalforces, for example:

Periodontal problems in the canines,

Cases of atypical upper lateral incisor agenesis, lower incisor extraction, or

In any case that the first premolar replaces thecanine. In this last example, the establishment ofthe lateral guide should be avoided in order toprevent the development of a traumatic occlusionbecause premolars are not capable of supportingdisocclusion.


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CENTRIC OCCLUSION is the occlusion a

person makes when they close their jawand fit their teeth together in maximumintercuspation. It is also referred to as aperson's habitual bite, bite of convenience,

or intercuspation position (ICP).

CENTRIC RELATION: not to be confusedwith centric occlusion, is a relationship

between the upper and lower jaw.
http://en.wikipedia.org/wiki/Maximum_intercuspationhttp://en.wikipedia.org/wiki/Maximum_intercuspationhttp://en.wikipedia.org/wiki/Maximum_intercuspationhttp://en.wikipedia.org/wiki/Maximum_intercuspation


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CENTRIC OCCLUSION

MUTUALLY PROTECTED


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MUTUALLY PROTECTED

OCCLUSION

During the jaw protrusive movement, the lower incisalborders slide on the palatal surfaces of the upperincisors, promoting total disocclusion. Likewise,

during the lateral movements, the canine mustperform the disocclusion. These concepts, known as"mutually protected occlusion", are important todefine the occlusal pattern in subjects with complete

dentition. Along those lines, the posterior teeth protect the

anterior teeth of any contact in the static jaw positionand during the excursive movements

E t bli h t f I di t


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Establishment of Immediate

Anterior Guidance

When the patient occludes in MI, all posterior teeth mustcontact, and the anterior teeth must be slightlyseparated.

As soon as the protrusive movement begins, the lowerincisors must contact the palatal face of the maxillaryincisors, thus allowing the immediate disocclusion of theposterior teeth.

For this purpose, some orthodontic parameters must be

present, for example, overjet and overbite. If the patientpresents an increased overjet (more than 3 mm), alonger period is necessary for the anterior teeth tocontact, which results in anterior guidance at theexpense of the posterior teeth.


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In 1976, Roth presented the following functional aspectsof the occlusion as being fundamental for completion ofthe orthodontic cases:

1. Teeth must present maximum intercuspal (MI) positionwith the jaw in centric relation (CR)

2. In centric relation, all posterior teeth must present axialocclusal contacts, and the anterior teeth must maintaina distance of 0.0005 inches between them.

3. During laterotrusion, the canines must disocclude theposterior teeth (canine guidance).

4. During protrusion, the upper anterior teeth must occludewith the lower anterior teeth and the first premolar or thesecond premolar (in extraction cases), aiming atdisoccluding all posterior teeth (immediate anteriorguidance).

5. No interference must be present on the balancing side.


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A. Make the joints and teeth simultaneously stable

Posterior contacts must be directed in the long axis ofthe teeth.

B. Create axis loading wherever possible

Anterior guidance such that the anterior teeth disclude

the posterior teeth in protrusive.

Canine guidance such that the canines disclude theposterior teeth in lateral excursions.

No occlusal contacts on the balancing side.C. Move off axis loading as far from the fulcrum aspossible


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General rules for diagnosis, evaluation andtreatment of occlusal problems

Make the joints and teeth simultaneously stable

Posterior contacts must be directed in the long axis of the teeth.

Create axis loading wherever possible

Anterior guidance such that the anterior teeth disclude the posteriorteeth in protrusive.

Canine guidance such that the canines disclude the posterior teethin lateral excursions.

No occlusal contacts on the balancing side.

Move off axis loading as far from the fulcrum as possible

MALOCCLUSION


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Any deviation from the normal occlusion is the mal-

occlusion

Mal-occlusion may be resulted in one of the following

systems

U L F A T

MALOCCLUSION

CLASSIFYING


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Qualitative

Quantitative

U L F A T

CLASSIFYING

MALOCCLUSION


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QualitativeIs a shorthand method of describing the

salient features of a mal-occlusion,

e.g; Angles classification

U L F A T


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QuantitativeIndices are used to measure the

malocclusion quantitatively

Each feature of a malocclusion is given a

score & the summed total is then

recorded (PAR index)

The worst feature of a malocclusion isrecorded (Index of Orthodontic

Treatment Need-IOTN)

U L F A T


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Angles ClassificationAngle, in 1899, described this classification

It was based upon antero-posterior dental

relationship

Based upon permanent 1st molar relationship

Divided into many classes of malocclusions

that are desi nated b Class I Class II &U L F A T


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Class I Malocclusion(Neutro-occlusion)

The permanent upper & lower 1st molars are

in normal relationship, but the rest of thedentition may have deviation from

normal occlusion, e.g; crowding,

rotations etc.

U L F A T


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Class II Malocclusion(Disto-occlusion)

The mesio-buccal cusp of permanent upper

molar occludes mesial (anterior) to the

lower 1st

molar mesio-buccal groove

It is further divided into

Class II Div 1 U L F A T

Cl II Di 1


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Class II Div 1

Along with class II molar relationship, theover jet is more than normal i.e. 2-3 mm

Molars may be in 1/4th unit, unit or full

unit or supra class II relationship

U L F A T


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Class II Sub-division (Rt)

Div 1

U L F A T


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Class II Div 2Along with class II molar relationship, the

overjet is reduced than normal

Further divided into;

Type A

Type B

Type C

U L F A T

Class III


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Class III(Mesio-occlusion)

The mesio-buccal cusp of permanent upper1st molar occludes distal (posterior) to

the lower 1st molar mesio-buccal groove

Class III sub-division, when one side is in

class I & other side in class III (class III

side will be Rt or Lt sub-division)

U L F A T


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Drawbacks of Angles

classificationThis is only for dentition & not for skeleton

Permanent 1st molars are not fixed points

Only depends on AP relationship

In case of extracted or missing 1st molars,

cannot be classified U L F A T


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Modifications in Angles

ClassificationLischers Classification:

He introduced the term Neutro-occlusion(same as Angles class I malocclusion)

Used the term Disto-occlusion(same as

Angles class II malocclusion) U L F A T



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Modifications in Angle s

Classification

U L F A T


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ClassificationLischers Classification:

Used the term Versionas a suffix fordifferent individual malocclusions, e.g;

Mesio-version

Linguo-version U L F A T


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Deweys Classification:

Modified Angles class I malocclusion as

following;

Type I Anterior crowding

Type II Maxillary incisors in

labial version

Type III Anterior X-bite U L F A T


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Deweys Classification:

He did not made any modification for Angles

class II malocclusion

But he made modification for Angles class

III malocclusion as following;

Type I Normal incisor overlappingU L F A T

British Standards Institute


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British Standards Institute

Classification:

Class I Lower incisor edges occlude withor immediately below the cingulum

plateau of the upper central incisors

Class II The lower incisors edges lie

posterior to the cingulum plateau of the

upper incisors

U L F A T

Further divided into 2 categories;


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Further divided into 2 categories;

Division 1: The upper central incisors are

proclined & there is an increase in overjet

Division 2: The upper central incisors are

retroclined & the overjet is usuallydecreased

U L F A T


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Class III The lower incisor edges lie

anterior to the cingulum plateau of the

upper central incisors & the overjet is

reduced or reversed

U L F A T


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Simons Classification

It is based upon 3 dimensional relationship

of the dental arches with 3 following

planes

U L F A T


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U L F A T


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Frankfort Horizontal Plane: This plane passes

thru lower most border of the bony orbit

to the upper border of the external

auditory meatus

This plane vertically relates dentition, closer

to the plane is called as Attraction,while away from it is know as

Abstraction

U L F A T


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Mid Sagittal Plane: This plane is

perpendicular to the Frankfort Horizontal

PlaneThis plane transversally relates dentition,

closer to the plane is called as

Contraction, while away from it isknown as Distraction

U L F A T


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Orbital Plane: It is a plane drawn

perpendicular to the Frankfort Horizontal

Plane, from lower most border of thebony orbit

This plane sagittally (A.P.) relates dentition,

forward to the plane is called asProtraction, while behind from it is

known as Retraction

U L F A T


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This classification is based upon skeletal

relationship

Skeletal Class I: There is a normal between

upper & lower arches, when maxillary

arch is slightly forward to the mandibular

arch

U L F A T

Ballards Classification


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Skeletal Class II: The lower apical base is

relatively far back from the upper apicalbase

U L F A T

Ballards Classification


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Ballard s Classification

Skeletal Class III: The lower apical base is

placed relatively far forward from the

upper apical base

U L F A T


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Ackermann - Proffit Classification

One of the most recent classification thatcovers all the tissues in the 3 planes of

space

Venn diagram

U L F A T


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WHAT IS AN INDEX ?

A RATING OR CATEGORIZING SYSTEM THAT

ASSIGNS A NUMERIC SCORE TO A PERSONS

OCCLUSION / AESTHETIC LOOK

AN OVERALL SCORE IS CALCULATED FOR

EACH TRAIT FOR GRADING MALOCCLUSION


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NEED FOR

ORTHODONTIC TREATMENT INDEX

LACK OF MANPOWER IN ORTHODONTICS

TO ESTABLISH A SIMPLER METHOD OR INDEX

OF ASSIGNING TREATMENT PRIORITY

TO MAKE A LIST OF TRAITS THAT DETERMINE

THE EXTENT TO WHICH TREATMENT IS NECESSAR

TO TREAT LARGE NUMBER OF PATIENTS

AT LOCAL LEVELS

PRINCIPLES OF ANY INDEX


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PRINCIPLES OF ANY INDEX

Most of the indices are developed upon two components

to record orthodontic treatment priority

The first of these components records need for treatment ondental health and functional grounds

The second component records the aesthetic impairment of

dentition on social-psychological grounds


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VARIOUS ORTHODONTIC INDICES

IOTN (Index of Orthodontic Treatment Need)

TPI (Treatment Priority Index)

PAR (Peer Assessment Rating) DFI (Dento-facial Index)

OFI (Occlusal Feature Index)

HMAR (Handicapping Malocclusion Assessment Record)

SOI (Summers Occlusal Index)

DAI (Dental Aesthetic Index)

SCAN (Standardized Continuum of Aesthetic need)


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REQUIREMENTS OF

INDEX OF ORTHODONTIC TREATMENT NEED

CLINICALLY VALID AND RELIABLE

QUICK TO APPLY

EASILY LEARNED BY EXAMINERS WITHOUTSPECIALIZED TRAINING

POSSIBLE TO APPLY ON EITHER PATIENTSOR DENTAL CASTS

ACCEPTABLE TO BOTH PROFESSION ANDPUBLIC


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BENEFICIAL USES OF IOTN

PREVALENCE OF MALOCCLUSION

TREATMENT NEED OF SCHOOL POPULATION / GENERAL PUBLIC

NATIONAL STUDY SURVEYS

PRIORITIZING CASES FOR FUNDED PROGRAMS

MONITORING AND PROMOTING STANDARDS


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BENEFICIAL USES OF IOTN

UNIFORMITY IN PATIENT IDENTIFICATION

REFERRAL BY GDPs TO ORTHODONTIST

AUDIT / COMPARING IN PRE- AND POST- OPERATIVE CASES

MAKING HOSPITAL / CLINIC WAITING LIST

RESEARCH / TEACHING


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COMPONENTS OF IOTN

DHCDENTAL HEALTH COMPONENT

ACAESTHETIC COMPONENT

IOTN


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DHC IS BASED ON

GRADE VGRADE IVGRADE IIIGRADE IIGRADE I

NO NEED LITTLE NEED MODERATE NEED GREAT NEED VERY GREAT NEED

MODIFICATION IN DHC


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MODIFICATION IN DHC

GRADE IV , VGRADE IIIGRADE I & II

NO / LITTLE NEED BORDER LINE NEED DEFINITE NEED


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PRINCIPLES OF GRADING DHC

ORDER OF PRIORITY

1 MISSING TEETH

2 OVERJET3 OVERBITE

4 CROWDING OF TEETH

5 CROSS-BITE

TRAITS THAT INCREASE MORBIDITY OF

DENTITION AND SURROUNDING STRUCTURES


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PRINCIPLES OF GRADING DHC

TRAITS THAT INCREASE MORBIDITY OF

DENTITION AND SURROUNDING STRUCTURES

EXAMPLE

OVERJET > 9mm = GRADE 5

CROWDING < 1mm = GRADE 1

PRIORITY GIVEN TO MOST SEVERE TRAIT

AESTHETIC COMPONENT


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MODIFICATIONS IN AC

PHOTOGRAPHS 1TO 4 = NO NEED

PHOTOGRAPHS 5 TO 7 = BORDER LINE NEED

PHOTOGRAPHS 8 TO10 = DEFINITE NEED


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It is the possibility of having adream come true that makes lifeinteresting.Paulo Coelho

( The Alchemist )

occlusion (orthodontics)

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