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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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key I: correct interarch relationship
4)The buccal cusps of the
maxillary premolars have a
cusp-embrasure (distal)
relationship with the mandibular
premolars
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key I: correct interarch relationship
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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key I: correct interarch relationship
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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key I: correct interarch relationship
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.
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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_intercuspation8/3/2019 Occlusion (Orthodontics)
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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
Modifications in Angles
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Modifications in Angle s
Classification
U L F A T
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Modifications in Angles
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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Simons Classification
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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Simons Classification
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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Simons Classification
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 )
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