Transcript EXTRACTIONS IN ORTHODONTICS

EXTRACTIONS IN ORTHODONTICS
21/01/2015
Dr.Gyan P.Singh
Associate professor
Department of Orthodontics&Dentofacial
Orthopaedics,FODS,KGMU
CONTENTS
• INTRODUCTION
• EVALUATION OF DIAGNOSTIC ELEMENTS
• CHOICE OF INDIVIDUAL TEETH
INTRODUCTION
• Generally there are three reasons to extract
the teeth;
1. To provide space for the alignment of
crowded teeth.
2. For the retraction of protruded teeth.
3. For camouflaging the skeletal class II and
class III malocclusions.
b. Wolff’s Law of bone:
 Bone trabeculae were arranged in response to
stress lines on the bone.
 This led Angle to 2 key concepts:
I. Skeletal growth could be readily influenced
by external pressure.
II. If teeth were placed in proper occlusion,
forces transmitted to teeth would cause
bone to grow around them and so
stabilizing them in a new position even if
great deal of arch expansion had occurred.
 These concepts did not go unchallenged.
Calvin Case argued that although arches
could always be expanded, neither esthetics
nor the stability would be satisfactory in
long term in many patients.
This controversy culminated in debate
between Angle’s student Dewey and Case.
Angle’s followers won the day.
2. THE RE-INTRODUCTION OF EXTRACTION IN
THE MID 20TH CENTURY.
Relapse after non-extraction treatment was
frequently observed by 1930.
 Charles Tweed & Raymond Begg, both adapted
‘EXTRACTION WHEN NECESSARY’ approach and
treated their patient with this philosophy.
They found that occlusion was stable and
esthetics was improved.
Intraoral Photographs (Pretreatment)
U.Occlusal
Frontal
L.Lateral
R.Lateral
L.Occlusal
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Intra oral photographs(Final Stage)
U.Occlusal
L.Lateral
Frontal
R.Lateral
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EVALUATION OF DIAGNOSTIC
ELEMENTS FOR EXTRACTION
CLINICAL PARAMETERS
I.
FACIAL
APPEARANCE
II. SOFT TISSUE
PROFILE
III. MIDLINE
IV. GROWTH
MODEL ANALYSIS
I.
CAREY’S MODEL
ANALYSIS
II. CURVE OF SPEE
III. BOLTON
DISCREPANCY
IV. IRREGULARITY
INDEX
CEPHALOMETRIC
VARIABLES
 VERTICAL FACIAL
PROPORTIONS.
I. FMA
II. SN-MP
III. JARABAK RATIO
 LOWER INCISOR
POSITION.
I. IMPA
II. FMIA
III. LOWER INCISOR
TO A-Pog
DISTANCE
CLINICAL PARAMETERS
I. FACIAL APPEARANCE:
• Facial appearance -consideration -planning
orthodontic treatment.
• Genetic makeup,
• Environmental influences,
• and cultural background.
• How extractions vs arch expansion affects
facial appearance is a major concern for
orthodontists.
II. SOFT TISSUE PROFILE.
• How extraction vs non-extraction therapy
affects the profile also is a concern.
• Extraction therapy is sometimes believed
to be detrimental to the profile.
P R E-T R E A T M E N T
Facial appearance of
the patient
following treatment
after 1Yrs and 9
months
P O S T -T R E A T M E N T
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• This is important because, if a patient has
proclined incisors or proclined incisors with
crowding.
• it would be virtually impossible to improve
the anteroposterior position of the teeth and
the patient’s profile without extractions.
III. MIDLINE:
• According to Strang , the harmonic
positioning of the midlines relative to each
other and to the face is what characterizes
normal occlusion.
• Any variation in this combination is indicative
of improper relationship between the teeth
or dental arches.
• This requires a careful diagnosis because
properly assessing the causes behind midline
shifts allows professionals to use unique
mechanics and asymmetric extractions.
• Patients presenting with severe dental
midline deviation relative to the face require
tooth extractions.
IV. GROWTH STATUS.
• In malocclusions with skeletal
discrepancies it is crucial—for the
diagnosis and prognosis of the case—to
check whether the patient is still
undergoing significant facial growth.
• If a malocclusion can be corrected with
growth response (growth redirection),
clinicians can handle the case without
extractions.
MODEL ANALYSIS
I. CAREY’S ANALYSIS:
• First determine the degree of discrepancy
between bone and tooth structure.
• If the discrepancy is 2.5 mm. or less, we do
not extract.
• If it is 2.5 to 5.0 mm., we extract the second
premolars, whenever possible, to obtain
better esthetics.
• If it is more than 5 mm., we extract the first
premolars.
• If the discrepancy is extreme (5 mm. or
more), in the lower arch and mild in the
upper, we extract the lower first and
upper second premolars, and vice versa.
• When the discrepancy is confined to the
maxillary arch, two upper first or second
premolars are removed, the choice
depending upon the degree of the
deficiency.
II. CURVE OF SPEE:
• Levelling the curve increases incisor protrusion.
• Recent studies conclude the real effect to be
closer to 1:3; for every 3 mm of curve levelled,
arch circumference increases 1 mm.
• The deeper the Curve of Spee, the greater the
need for extraction.
III. BOLTON DISCREPANCY.
• An interarch tooth-size discrepancy may provide
incentive to extract in order to establish a proper
occlusion. This diagnostic variable has been
popularized as the Bolton discrepancy.
• Clinicians have utilized interproximal reduction to
resolve interarch tooth size discrepancies.
• Bolton noted a 4 mm limit to anterior
reduction. Thus, extraction may be necessary
to resolve a discrepancy greater than this.
CEPHALOMETRIC VARIABLES
 VERTICAL FACIAL PROPORTIONS:
I. SN-MANDIBULAR PLANE ANGLE(SN-MP)
• Schudy utilized the angle formed at the
intersection of the sella-nasion and
mandibular planes (SN-MP)to aid in his
assessments, and found the value of 33
degrees to be average for balanced vertical
facial types, with a range of 31 to 34 degrees.
II. FRANKFORT MANDIBULAR PLANE ANGLE(FMA).
• The FMA provides an additional vertical
appraisal to the SN-MP measurement.
• A normal value for the FMA is in the range of 20
to 30 degrees.
• Values above these normal ranges are
associated with skeletal open bite, whereas
values below are typically associated with
skeletal deep bite.
III. JARABAK RATIO:
• The PFH (distance between sella and
gonion) is divided by the AFH (distance
between nasion and menton).
• The normal value is 61-69%.
• Less than 61% suggests a skeletal open
bite; greater than 69% indicates a skeletal
deep bite.
• Treatment geared toward
achieving facial balance is
more likely to extract in
skeletal open bite and not
extract in cases with
skeletal deep bite .
 LOWER INCISOR POSITION:
I. INCISOR MANDIBULAR PLANE ANGLE(IMPA):
• Charles Tweed used the orientation of the
mandibular incisor to aid in treatment planning
to create facial balance and harmony.
• He noted a need for “upright” and “vertical”
lower incisors.
• Margolis proposed the incisor mandibular plane
angle (IMPA) to quantitatively define these two
qualities.
• He proposed IMPA to be 90+/-3 degrees
in normal, balanced faces.
• According to Tweed, this value can range
between 85 and 95 degrees, and vary
according to ethnicity.
• Values above this range are indicative of
extraction to improve functional and
esthetic imbalance.
II. FRANKFORT MANDIBULAR INCISOR
ANGLE(FMIA):
• The norm for the angle formed by the
intersection of the Frankfort plane and the long
axis of the lower incisor is 60-70°.
• A value less than 60° indicates proclination of
the lower incisors, whereas a value greater than
70° suggests that the lower incisors are
retroclined.
III. LOWER INCISOR TO A-Pog
DISTANCE:
• McNamara found the proper position
of the mandibular incisor to be 1 to 3
millimeters anterior to the line from
point A to Pogonion (A-Pog) in a
well-balanced face, regardless of age.
EXTRACTION WIGGLEGRAM
CHOICE OF INDIVIDUAL TEETH
1. UPPER INCISOR EXTRACTION:
 INDICATIONS:
• Unfavorably impacted incsor.
• Buccally or lingually blocked out lateral
incisor with good contact between central
incisor and canine.
• Congenitally missing one of lateral incisor,
opposite incisor may require extraction to
maintain arch symmetry.
• Grossly carious incisor.
• Malformed incisor that can not be
restored.
• Trauma or irreparable damage.
• An incisor with dilacerated root.
2. LOWER INCISOR EXTRACTION:
• In 1905, Jackson described a case in which
two lower incisors were extracted at different
times to relieve mandibular crowding.
• Hahn(1942) advocated the removal of a
mandibular incisor to close the space and
thus reduce the anterior dentition.
INDICATIONS:
• Permanent dentition,
• Minimal growth potential,
• Class I molar relationship,
• Harmonious soft-tissue profile,
• Minimal-to-moderate overbite,
• Little or no crowding in the maxillary arch,
• Existing Bolton discrepancy and
• Tooth-size-arch-length discrepancy of more
than 5mm in the anterior region
 WHICH INCISOR TO BE REMOVED?
• Periodontal conditions,
• The presence of gingival recession, and
• The location of any restorations,including
endodontic treatment.
• Extraction of a lateral incisor is generally
preferred because it is less visible from the
front.
2. USE OF RECTANGULAR WIRE:
3. CANINE EXTRACTION INDICATIONS:
• Extremely unfavourable cuspid position.
• Tooth position unfavourable for orthodontic
movement.
• Anklosed tooth.
• Internal or external root resorption.
• Severe dilacerataion.
Transmigrated canine in mandibular arch
4. PREMOLAR EXTRACTION:
• In 1949, Nance stated that the term extraction
had, at that time, become synonymous with
the removal of all four first premolars.
• Augmenting anchorage, maximum lip
retraction, better contact between the canines
and second premolars , and the fact that first
premolars are nearer to anterior crowding are
some of the reasons behind favouring their
extraction.
1ST PREMOLAR
EXTRACTION
2ND PREMOLAR
EXTRACITON
ANCHORAGE
NOT SIGNIFICANT
NOT SIGNIFICANT
LIP RETRACTION
NOT SIGNIFICANT
NOT SIGNIFICANT
FACIAL VERTICAL
DIMMENSION
NOT SIGNIFICANT
NOT SIGNIFICANT
TOOTH SIZE
DISCREPANCY
MORE EVIDENT
LESS EVIDENT
CLINICAL
CONSIDERATIONS
NOT FAVOURABLE
FAVOURABLE
MOTHER NATURE’S
RULE
DOESN’T ALLOW
ALLOW
Enmasse
Retraction of
Upper and Lower
Anterior Teeth
{Preformed T.P.A.=Molar stabilization}
K-Sir Retraction
Spring
NiTi Retraction spring
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5. 1ST MOLAR EXTRACTION:
• “First permanent molar extractions doubling
the treatment time and halving the
prognosis” was the phrase coined by Mills.
• Daugaard-Jensen suggested that first molar
cases are no more time consuming than 4
premolar cases.
• Williams and Hosila highlighted the fact that
first molar extraction cases are likely to have
less effect on the profile than premolar
extraction cases.
INDICATIONS:( Sandler et al 2000)
• Extensively carious first molars
• Hypoplastic first molars
• Heavily filled first molars where premolars are
perfectly healthy
• Apical pathoses or root canal treated first
molars
• Crowding at the distal part of the arches and
wisdom teeth reasonably positioned
• High maxillary/mandibular planes angle
(Anterior open bite cases)
• TIMING OF EXTRACTIONS:
If the upper second molars are unerupted at the
time of extraction of the upper first molars, they
will almost completely replace them, thus
contributing little space for correction of the
malocclusion.
 If there is a space requirement in the upper arch
therefore, extraction of the first molars must be
delayed until the second molars have erupted
sufficiently to allow a palatal arch with Nance
button or headgear to be placed.
6. 2ND MOLAR EXTRACTION:
INDICATIONS(Lehmann 1979)
• The second molars are severely carious,
ectopically erupted, or severely rotated.
• Skeletal Class I malocclusions with arch length
discrepancy in the distal part of the arch or with
mild anterior crowding and
• In Class II "skeletal" cases with only mild
crowding of the mandibular arch.
 ADVANTAGES:
• Disimpaction of third molars
• Faster eruption of third molars
• Prevention of "dished-in" appearance of the
face at the end of facial growth
• Prevention of "late" incisor imbrication
• Facilitation of first molar distal movement
TIMINGS OF EXTRACTION: (Kokich 1983)
• The third molar crowns should be
completely formed but extractions should be
performed before the roots begin to develop;
• The axial inclination of the third molar buds
should not be greater than 30 ° relative to
the occlusal plane;
• The mandibular third molar should be in
close proximity to the second molar roots to
ensure adequate mesial drift of the third
molar as it erupts.
MCQ:
1.Extraction of teeth in conjunction to orthodontic treatment is
necessary in order to
(A) To relieve crowding in the arches especially when jaws are
not large enough to accommodate all the teeth
(B) To achieve proper sagittal inter-arch relationship
(C) Just as a procedure of orthodontics
(D) Both A and B
2. The decision of extraction is based on the following factors
(A) Patient’s age
(B) Sex of the patient
(C) The amount of space needed for tooth alignment
(D) All of the above
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3.The decision to opt for extraction should only be made
(A) After careful clinical evaluation
(B) After model analysis done
(C) After cephalometric tracing done
(D) All of the above
4. Injudicious extraction of teeth can cause
(A) Arch collapse
(B) Deep overbite
(C) Spacing and tissue damage
(D) All of the above
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5.Who was the major proponent of “ Non Extraction
Philosophy”
(A) Edward H Angle
(B) Calvin Case
(C)John Hunter
(D)All of the above
6. Who introduced the concept of extraction as a part of
orthodontic treatment.
(A)
(B)
(C)
(D)
Calvin Case
Charles Tweed
Angle
Jhon Hunter
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7.Most commonly extracted teeth for orthodontic purpose are
(A) Maxillary first molars
(B) Maxillary and mandibular premolars
(C) Mandibular incisors
(D) Maxillary incisors
8. The tooth most rarely extracted as a part of orthodontic treatment
(A) Maxillary central incisors
(B) Maxillary third molars
(C) Mandibular third molar
(D) Maxillary and mandibular premolars
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9. What are the different extraction procedures?
(A) Balanced extraction
(B) Compensatory extraction
(C) Enforced extraction
(D) All of the above
10. Compensatory extraction refers to
(A) Extraction of tooth in the opposite jaw to the same teeth
group
(B) The extraction of a tooth in the same jaw to the same teeth
group
(C) The extraction of a tooth in the cotralateral side to the
same teeth group
(D) None of the above
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REFERENCES
1. Graber TM:Principles and Practicce
Orthodontics,WB Saunders,1988
2.Profitt.Contemporary Orthodontics,Elsevier
India.3rd ed.,2000.
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