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1. INDIAN DENTAL ACADEMY
Leader in continuing dental education
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2. TWEED-MERRIFIELD
DIAG NOSIS
Identification & Classification of
Orthodontic & Orthognathic
disharmonies
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3. Tweed’s contribution

IMPA:

Tweed treated series of cases first by non extraction,
then by extracting 4’s, if necessary. The results of the
extraction cases were more gratifying and he was near
to his visualization of balance and harmony of the face.
In these successfully treated cases he observed that
the inclination of the lower incisors to the mandibular
plane was in the range of 90 (+5 or –5).

Thus he concluded that normal range of
mandibular incisor inclination, when related
mandibular plane is 90+ 5.
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4. 
FMA

Patients were placed in the head holder with head
oriented on FH plane using the forefinger and thumb,
he outlined and extended the mandibular plane
posteriorly to connect to FHP with the result of this
study, be concluded that the normal variation
of FMA is 16˚-35 ˚, with average of 25 ˚

FMIA



The sum of all the angles in a triangle is 180˚, if the
norm for IMPA is established at 90˚, norm for FMA
at 25˚, the third angle FMIA must be 65˚
All the patients with large FMA need compensation
of mandibular incisor inclination.
Meaning in high angle cases, the lower incisor are
slightly proclined.
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5. Merrifield’s contribution

Merrifield’s diagnostic philosophy outlined follows:

Recognize and treat with the dimension of dentition.
This means non-expansion of malocclusion when the
normal muscular balance exists.

Recognize the dimensions of lower face and treat for the
maximal facial harmony and balance.

Recognize and understand the skeletal pattern.
Diagnose & treat in harmony with normal growth &
development
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6. Diagnosis of Orthodontic and
Orthognathic disharmony
should be based on four major
areas
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Facial
Dental
Cranial
Environmental

7. Facial Disharmony




Facial proportion is one of the greatest challenges &
opportunities for clinical orthodontist
Most patients desire & demand esthetic
improvement, which includes beautifying the smile
& allowing normal lip postures
Merrifield & others have pointed out that the upper
& lower lips are very responsive to maxillary incisor
tooth movements.
Merrifield concluded that 4mm of upper incisor is
accompanied by 3mm of upper lip retraction & 1mm
of upper lip thickening
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8. 





The chin-lip relationship can be defined
And also be related to other elements in face such as
the nose, naso-labial contour, the smile line etc.
Lower facial contour is a responsibility of orthodontic
specialty
LFH is very responsive to proper tooth repositioning
And in extreme cases surgical intervention supervised
by orthodontist can achieve necessary balance &
harmony of lower face
Hence identifying & classifying facial
disharmonies must be an integral part of our
service to our patients & recognized as one
of our first responsibilities
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9. Dental Disharmony



Teeth, their relationship to each other 7 to the
supporting bones have been the overriding concern
of Orthodontist since Angle.
Angle’ s system is considered standard for more than
100 years,.
However disharmonies of teeth can be better
understood & identified by using a comprehensive
space analysis system including all 32 teeth &
determining whether a space deficit or space surplus
exists as well as analysis of the occlusal relationship
of maxillary teeth to the mandibular teeth
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10. 


Orthodontic treatment is a space management
procedure. Space can neither be created nor
destroyed by orthodontist
Space management must use the elimination of
certain dental units to allow spatial relationship of
the remaining dental units. This is not space making,
but it is judiciously using the available space
It is also crucial to identify the areas of dentition that
have space deficit or surplus. In this way the
orthodontist can most advantageously use space
management to correct the most overriding
disharmonies
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11. Cranial Disharmony



To strive for a harmonious relationship of maxilla &
mandible to the cranial base & to each other is an
important responsibility of the orthodontist
Disproportion of these bones or malrelationships with
other bones in the cranium can be favorably
influenced by dental repositioning during growth
period.
Orthognathic surgical intervention , supervised by
orthodontist, in extreme disharmonies can result in reestablishing a better relationship between maxilla to
the mandible and to the surrounding bones of the
cranium
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12. 




Environmental
Disharmony
The most challenging area of orthodontic treatment is to
correct environmental abnormalities.
Hence orthodontist must understand mother nature &
knowledge of the functional and static elements
associated with dentition, face & cranium.
Bones, muscles, blood supply, nerve supply, joints &
other soft tissues make-up the environment
Functional elements:- Joints, muscles of
expression, mastication, deglutition, speech & breathing
Static elements:- Bone, cartilage & soft tissue
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13. Classification of
Orthodontic &
Orthognathic
disharmonies

Facial
Horizontal Disharmonies
 Disharmonies of facial convexity
 Disharmonies of facial concavity
 Vertical Disharmonies
 Excessive facial height
 Diminished facial height

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14. 
Dental

Arch length disharmonies





Arch Width disharmonies





Mandibular arch space deficit
Mandibular arch space surplus
Maxillary arch space deficit
Maxillary arch space surplus
Mandibular arch width deficit
Mandibular arch width excess
Maxillary arch width deficit
Maxillary arch width excess
Occlusal Relation disharmonies


Distal occlusion
Mesial occlusions
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15. 
Cranial
 Horizontal




Mandibular retrognathism
Mandibular prognathism
Maxillary retrognathism
Maxillary prognathism
 Vertical


disharmonies
disharmonies
Hyperdivergent cranial patterns
Hypodivergent cranial patterns
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16.  Environmental
 Internal


Muscles & other soft tissue disharmonies
Bone & joint disharmonies
 External


Habits
Trauma
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