Introduction to Orthodontics Fifth Year

1. 


Planning for Orthodontic Treatment
Introduction
o Special consideration in early treatment
 For a child with a complex problem, it is highly likely that a second stage of treatment in the
early permanent dentition will be required, even if early treatment is carried out effectively
and properly.
 When limited treatment is done in the mixed dentition. It is highly likely that a second stage
of the treatment will be required later, or a less-than-ideal result will have to be accepted. It
is difficult to have ideal relationships when only one arch is treated.
 There are important biomechanical differences between complete and partial appliances:
 The typical fixed appliance for mixed dentition treatment is a ‘2x4’ arrangement (2
molar bands, 4 bonded incisors)
 When a fixed appliance include only some of the teeth. Archwire spans are longer.
Large movements are easy to create, and the wires themselves are springier and less
strong.
 Anchorage control is both more difficult and more critical:
 With only the first molars available as anchorage in the posterior segment of the
arch. There are limits for the amount of tooth movement that should be attempted in
the mixed dentitions.
 In addition, stabilizing lingual arches are more likely to be necessary as an adjunct to
anchorage.
 Retention is often needed between mixed dentition treatment and eruption of the
permanent teeth:
 After any significant tooth movement, it is important to maintain the teeth in their
new position until a condition when retention is used between early (phase 1) and
later (phase 2) treatment, creative planning of bow and clasps position is required to
avoid interference with erupting teeth and maintain the effectiveness of the clasps.
Space deficiency problem
o Space management
 Management of incisor crowding
 Some children have considerable incisor irregularity in the mixed dentition due to the
transitional incisor crowding, but space analysis shows that if loss leeway space from
mesial drift of first permanent molars could be prevented, there would be no space
deficiency.
 For other patients, the large leeway space would nearly accommodate all the teeth
and only a small amount of expansion would be required if mesial movement of the
molars were prevented.
 When this strategy for treatment of crowding I adopted, intervention begins as late
as possible and capitalizes most on the space differential between the primary
second molar, sometimes known as the “E space”
 It is critically important to prevent either mesial movement of the first molars or
lingual tipping of incisors, so appliance therapy at least in the form of a lingual arch
will be necessary from the time any primary teeth are extracted until the end of the
transition to the permanent dentition.
 Usually a combination of early extraction of primary canine and disking to reduce the
width of the primary molars is necessary to allow the permanent incisors, canine, and
premolars to erupt and align.
Correction of molar relationship
o Because the molars have not been allowed to shift into leeway space when space management is
employed, they often are maintained in the end-to-end relationship that is normal before the
premolars erupt instead of moving into class I relationship.
o For that reason, space management also must include treatment to obtain a class I molar relationship
(i.e. if the lower molar is prevented from coming forward, the upper molar must be moved back)

2. o
o
In the mixed dentition, the possibilities are extraoral force (headgear to the molars) or some type of
molar distalization appliance.
The more the child wear the headgear, the better; 14 to 16 hourday is minimal. Approximately 10
gm of force per side is appropriate. The teeth should move at the rate of 1 mmmonth, so a
cooperative child would need to wear the appliance for 3 months to obtain the 3 mm of correction
that would be a typical requirement in this type of treatment.

Sever localized space loss >3mm
o When localized space loss is 3 mm or more, the decision must be made either to attempt to regain
the space, accepting the need for major tooth movement and complex appliance therapy, or to
extract a permanent tooth.
o Either way, a second stage of comprehensive treatment in the early permanent dentition is likely to
be needed.
o Maxillary space regaining, bilateral space loss, as in bilateral drift of both first molars after early
extraction of both primary second molars, creates a condition identical to the one described under
space management if the drift is not too severe.
o Moving both molars back up to 3 mm can be accomplished with either headgear or an intra-arch
appliance.
o The more typical space regaining situation is unilateral loss of space.
o Failure to maintain space after extraction of a carious maxillary second primary molar, or ectopic
eruption of the permanent first molar are the major causes.
o For unilateral space regaining, a fixed intra-arch appliance is preferred. This would be essentially
identical to the one made for bilateral use but with only one side activated.

Sever generalized arch length deficiency >4mm
o These children have little developmental spacing between primary incisors and occasionally some
crowding in the primary dentition.
o The two major symptoms of severs crowding in early mixed dentition are severe irregularity of the
erupting permanent incisors and early loss of primary canines caused by eruption of the permanent
lateral incisors.
o Finally, arch expansion can be obtained by aligning the anterior teeth with bonded attachment and
arch wires, and this can be combined with other types of expansion.
o The teeth can be tipped facially and buccally, increasing the available arch length.
o Very severe crowding: serial extraction: When the first premolars have erupted they are extracted
and the canine erupt into the remaiing extraction space.
o The residual space is closed by drifting and tipping of the posterior teeth unless full appliance therapy
is implemented.

Excess space
o Large maxillary midline diastema:
 There are two reasons for closing a maxillary midline diastema:
 To improve esthetics
 To provide enough space for the permanent canine to erupt when the separated
central incisor have forced the lateral incisors into the canine space.
 In a child whose permanent canines have not yet erupted, a diastema of 2 mm or less is likely
to close spontaneously and is not an indication for treatment.
 A diastema greater than 2 mm is unlikely to close spontaneously.

Generalized spacing with protrusion
o This closing loop arch wire was used to retract protrusive maxillary incisors and close space.

3. o
Each loop saw activated approximately 1 mm per month, and the posterior anchorage was reinforced
with a headgear.

Eruption problems
o Supernumerary teeth
 Supernumerary teeth can disrupt both the normal eruption of other teeth and their
alignment if and when they do erupt.
 Treatment is aimed at extraction of the supernumeraries before problems arise, or at
minimizing the effect if other teeth have already been displaced.

Managing sequelae of delayed eruption
o Delayed incisors.
o Some evidence indicates that changes in the overlying keratinized tissue occur in (….)
o Unerupted canine sometimes require surgical exposure and traction to bring them into position in
the dental arch.
 Initial traction with elastomeric chain
 Movement continued using arch wire
 Tooth into position

Cross bite of dental origin
o Posterior crossbite