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Orthodontics for
Internship program
Classification Of Malocclusion
• In order to assess the need for orthodontic
treatment, various indices have been
developed.The one used most commonly in
the United Kingdom is the Index of
Orthodontic Treatment Need(IOTN). This
index attempts to rank malocclusion, in order,
from worst to best. It comprises two parts, an
aesthetic component and a dental health
component .
• The dental health component consists of a series of
occlusal traitsthat could affect the long-term dental
health ofthe teeth. Various features are graded from 1–
5(least severe — worst). The worst feature of the
presenting malocclusion is matched to the list and
given the appropriate score.
• The aesthetic component consists of a series of ten
photographs ranging from most to least attractive. The
idea is to match the patient’s malocclusion as closely as
possible with one of the photographs
Patient assessment and
examination I
It is helpful to follow the examination
• Skeletal pattern
• Soft tissues
• Temporomandibular joint examination
Patient assessment and
examination II
• There are various systems available to assess this
aspect in the following sequence
Dental health
Lower arch
Upper arch
Teeth in occlusion
Treatment planning
Some of the problems that may need to be
addressed during treatment are:
• Improve dental health
• Relieve crowding
• Correct the buccal occlusion
• Reduce the overbite
• Reduce the overjet
• Align the teeth
Relieve crowding
• The decision to extract teeth needs to be
carefully considered and depends on the
degree of crowding, the difficulty of the case
and the degree of overbite correction.
Correct the buccal occlusion
• The key to upper arch alignment is to get the
canines into a Class I relationship.
• In order to get the canines Class I there are, in
general two choices for the molar relationship at
the end of treatment; either Class I or a full unit
Class II.
Overbite and overjet reduction
• The overbite should always be reduced before
overjet reduction is attempted. A deep
overbite will physically prevent the overjet
from being reduced because of contact
between the upper and lower incisors.
• Retainers are designed to reduce the risk of
relapse post treatment by allowing remodelling
and consolidation of the alveolar bone around
the teeth and reorganization and maturation of
the periodontal fibers.
• There are many different types of retainers but
they are generally removable or fixed. There are
no hard and fast rules regarding the length of
time retention should continue.
Cephalometric Analysis
• Standardised technique to ensure
reproducibility and minimise magnification.
• X-ray source at a fixed distance to the
midsagittal plane (about 152.5cm) and to the
film .
Uses of lateral cephalometric analysis
• To aid diagnosis by allowing dental and
skeletal characteristics of a malocclusion to be
• To check treatment progress during fixed or
functional treatments and to monitor the
position of unerupted teeth.
• To assess treatment and growth changes
Class I malocclusion
• Mild crowding is best accepted
• Moderate crowding usually
requires first premolar
• Severe crowding is often
managed expediently by the
removal of most displaced
teeth or by the extraction of
more than one tooth per
quadrant. Anchorage planning
is critical .
• Late lower labial segment
crowding is common in mild to
late teens.
Class I malocclusion Spacing
• Spaced dentition is generally rare
in Caucasians. It results from a
disproportion in the size of the
teeth relative to the arch size, or
from the absence of teeth. When
spacing is mild, acceptance is
usually best, or consider
composite additions or porcelain
veneers to increase the
mesiodistal width of the l abial
segment teeth. If spacing is more
marked, orthodontic treatment to
localise spacing at specific sites
may be necessary prior to fitting
a prosthesis or to implant
Class II division 1
• Growth modification. This is only
possible just before and during
the pubertal growth spurt using a
functional appliance, headgear, or
• Orthodontic camouflage. This
usually involves the extraction of
4[4 and fixed appliances to bodily
retract upper incisors to achieve
class II molar occlusion.
• Orthognathic surgery. This is
indicated where there is a marked
Class II skeletal pattern with
considerably reduced or
increased facial proportions
and/or a gummy smile in an
Class II Division 2
Class III malocclusion
Consider the degree of
anteroposterior and vertical skeletal
discrepancy, the potential direction
and extent of future facial growth,
incisor inclinations, the amount of
overbite, the ability to achieve
edgeto- edge incisor relationship, and
the degree of upper and lower arch
crowding. The prognosis is usually
more favourable where the skeletal
pattern i s mildly Class III with
average to low FMPA, deep overbite,
upper arch crowding, proclined lower
incisors, and the ability to achieve an
edge-to-edge incisor relationship
• Buccolingual molar relationship of upper and
lower teeth.Anterior or posterior (unilateral or
bilateral)with or without mandibular
• Buccal crossbite. Lower teeth occlude buccal to
corresponding upper teeth
• Lingual crossbite (scissors bite). Lower teeth
occlude lingual to palatal cusps of upper
Anterior crossbite
• If one or two incisors
are in crossbite,
displacement usually
exists. Correct early in
mixed dentition if
adequate overbite is
Posterior Crossbite
Scissors Bite
Anterior Openbite
A canine that is prevented from erupting into a normal position, either by bone,
tooth or fibrous tissue, can be described as impacted.
Correction of canine position Favourable indications for correction of
impacted canines.
The treatment of buccally or palatally impacted canines involves exposure and
then a form
of traction to pull the tooth into the correct
position in the arch.
Other options include:
Accept and observe
Extract the impacted canine
Removable Appliances
Removable Appliances
1. Springs
2. Bows
3. Screws
Retention component •
1. Adams clasp.
2. Southend clasp.
3. Long labial bow. 0.7 mm
wire (0.8 mm if it includes
reverse loops).
• Baseplate:This is usually
made of cold-cured
acrylic but may be heatcured. It connects the
other components;
guards palatal springs;
aids anchorage by contact
with the palate and with
teeth intended not to
move; and transfers
active component forces
to the anchorage. It may
also be active.:
1. Flat anterior bite plane.
2. Posterior bite platform.
Removable Functional Appliances
Fixed Appliances
• An appliance fixed to teeth by attachments through which
force application is by archwires or auxiliaries.
• Indications for fixed appliances:
1.Bodily movement, particularly of incisors to correct
mild to moderate skeletal discrepancies;
2. Overbite reduction by incisor intrusion;
3. correction of rotations extensive lower arch treatment;
4. alignment of grossly misplaced teeth, particularly those
requiring extrusion;
5. closure of spaces;
6. multiple tooth movements required in either one or both
Components Of Fixed Appliances
Anchorage Control
Extraoral Anchorage &Distilization
A Reverse pull Headgear to treat Class
III malocclusion
Risks of Orthodontic treatment
Root resorption
Enamel demineralisation/caries
Periodontal tissues
Orthodontic Tooth Movement
Properties of wires
Properties of wires
Consider wire as a beam •
elasticity - temporarily deform –
hardness - resistance to indentation –
proportional limit - point at which wire –
permanently deforms
range - amount of deflection prior to permanent –
stiffness - force required to bend wire –
Properties of wires
Properties of wires
• strength of materials
the capacity of materials to withstand stress
(the internal force exerted by one part of an
elastic body upon an adjoining part) and strain
(the deformation or change in dimension
occasioned by stress). Hooke's law states that,
within the elastic limit, strain is proportional
to stress.