Introduction to Orthodontics Fifth Year

1. Space Provision(Dr.Hosam Baeshen Lecture)

In some children space analysis shows that enough space for all the
permanent teeth ultimately will be available, but relatively large permanent
incisor and primary molars cause transient crowding of the permenant
incisor.

This crowding is usually expressed as mild faciolingual displacement or
rotation of individual anterior teeth.

Studies of children with normal occlusion indicate that when they go through
the transition from the primary to the mixed dentition, up to 2 mm of incisor
crowding may resolve spontaneously without treatment.

As a general rule there is no need for treatment when less than 2 mm of
incisor crowding is observed during the mixed dentition.

Not only is reduction of this small amount of crowding probably not
warranted, there is no evidence that long-term stability will be greater if the
child receives early treatment to improve alignment.

However, if exaggerated parental concern creates a problem, or if slightly
more anterior irregularity is present, one could consider disking the
interproximal enamel surfaces of the primary lateral incisor or canines as the
anterior teeth erupt.

Minor amounts of disking do not cause patient discomfort, but maximum
disking may require local anesthetic and produce some postoperative
sensitivity.

It is possible to gain as much as 3 to 4 mm of anterior space through this
procedure.

Because up to 2 mm of crowding may resolve spontaneously, this method
should probably be reserved for situations when 3 to 4 mm of anterior
crowding exist.

2. 
Meanwhile, correction of any incisor rotations caused by this transitional
crowding requires controlled movement to align and derotate them, using an
arch wire and bonded attachments on the incisors.

It may be wise to defer this therapy until comprehensive treatment is begun
in the early permanent dentition.

If the transitional crowding is great enough that there is considerable
crowding when the permanent canines erupt even though there is adequate
total space available, the patient really requires a more aggressive form of
space supervision and treatment known as space management .

This crowding occurs because the combined width of the erupting permanent
canine, first primary molar, and primary second molar is greater than the
total width of the permanent canine and premolars(3+D+E > 3+4+5).

Because manipulation of the leeway space ultimately will require adjustment
of molar relationships, it is considered a more complex type of treatment.
Localized space loss(3 mm or less)

After premature loss of a primary tooth, space may be lost from drift of other
teeth before a dentist is consulted.

Then, repositioning the teeth to regain space rather than just space
maintenance to stabilize the situation is required.

Up to 3 mm of space can be re-established in localized area with relatively
simple appliances and a good prognosis.
Maxillary space regaining

Generally, space is easier to regain in the maxillary arch than the mandibular
arch because of the increased anchorage for removable appliances afforded
by the palatal vault and the possibility for use of extraoral force(headgear).

3. 
Space lost from tipping can be regained when the crown of the tooth is
tipped back to its original position, but space lost by bodily tooth movement
requires that the tooth be bodily repositioned.

A removable appliance retained with Adams' clasps and incorporating a
helical fingerspring adjacent to the tooth to be moved is very effective.

This appliance is the ideal design for tipping one molar. One posterior tooth
can be moved up to 3 mm distally during 3 to 4 months of fulltime appliance
wear.

The spring is activated approximately 2 mm to produce 1 mm of movement
per month.

If bodily movement of one or both permanent maxillary first molars is
necessary in regaining space, it sometimes can be accomplished by using
headgear or an arch wire with excellent anchorage.

Regardless of the method used to regain these limited amounts of space, a
space maintainer is required when adequate space has been restored.

A fixed space maintainer is recommended, rather than trying to maintain the
space with removable appliance that was used for space regaining.
Mandibular space regaining

Removable appliances can be used for space regaining in the mandibular arch
just as they are in the maxillary arch, but as a rule they are less satisfactory
because they are more fragile and prone to breakage, and because they do
not fit as well.

Problems with tissue irritation frequently are encountered, and patient
acceptance tends to be poorer than with maxillary removable appliances.

If space has been lost on one side of the mandibular arch, the appliance of
choice is a removable lingual arch incorporating a loop that can be opened
to provide the necessary distal force.

4. 
An alternative fixed appliance for mandibular space regaining is the lip
bumper. Which is a labial appliance fitted to tubes on the molar teeth.

The idea is that the appliance presses against the lip, which creates a distal
force to tip the molar posteriorly.

Depending on the type of lip bumper used and its clinical manipulation,
transverse widening also may occurs.

Although some posterior movement of the molars can be observed when a
lip bumper is used, the appliance also alters the equilibrium of forces against
the incisors, removing any restraint from the lip on these teeth.
 The result is that forward movement of lower incisor occurs with a lip
bumper.

On balance, the effects of the active lingual arch and the lip bumper are
similar.

A lingual arch can be left in places a space maintainer after space has been
regained.

A lip bumper is not a good space maintainer and should be replaced with
band and loop maintainers or a lingual arch for long-term maintenances of
the space that was regained.
Generalized moderate crowding ( 4 mm or less)

Children with incisor crowding and small space discrepancies can be treated
with modest amounts of arch expansion during the early mixed dentition.

Early Vs late treatment……..

Some practitioners have advocated arch expansion in the primary and early
mixed dentitions on the theory that this would assure more space at a later
time.

However, to date, there is no credible evidence that early intervention to"
prepare," "develop," "balance," or expand arched by any other name has any

5. efficacy in providing a less crowded permanent dentition at a substantial
post-retention time point.

The major reason for early intervention for incisor crowding in a child who
has moderate space discrepancy, is esthetic concern because of obvious
crowding.

The amount of disking required to alleviate the crowding would expose the
pulps of the primary canines or cause extreme sensitivity.

The options are to (1) remove the primary canines as the crowding occurs,
which allows better alignment but creates the possibility that the permanent
incisor will tip lingually, reducing the arch length even more, or (2) move the
teeth facially into larger arch circumference.

A conservative approach to this diastema is to place a lingual arch after the
extraction of the primary canines and allow the incisors to align.

Ultimately the lingual arch or another appliance can be used to increase the
arch length.

A more aggressive alternative is early arch expansion, moving the teeth
facially .

Lower incisor teeth usually can be tipped 1 to 2 mm facially without much
difficulty, which creates up to 4 mm of additional arch length.

The other method is to band the permanent molars, bond brackets on the
incisor, and used a compressed coil spring on a labial arch wire to gain the
additional space.

When expansion by tipping the incisor facially is indicated, two methods
should be considered.

One is to use a removable lingual arch.

The multiple band and bond technique is usually followed with a lingual arch
for retention.

6. 
What distinguishes these two methods is the ability of the bonded and
banded appliance to provide rotational and mesiodistal space control, while
the lingual arch can only tip the teeth.

Sever crowding problems:
-
Expansion versus extraction.
-
Extraction is indicated if crowding is more than 10 mm.
Ectopic eruption

Eruption is ectopic when a permanent tooth causes either resorption of a
primary tooth other than the one it is supposed to replace or resorption of an
adjacent permanent tooth.

When the permanent lateral incisor erupts, resorption of the primary canine
is common.

Loss of the primary canine from ectopic eruption usually indicate space
enough space for all the permanent incisor, but occasionally may result solely
from an aberrant eruption path of the lateral incisor.

When only one primary canine is lost prematurely, the lateral incisor will
erupt into the primary canine space on that side and the midline usually will
shift in that direction.

If both mandibular canines are lost, the permanent incisor can tip lingually,
which reduces the arch circumference and increases the apparent crowding.
In either case, space analysis, including an assessment of the anteroposterior
incisor position and the facial profile, is needed to determine whether space
maintenance, space regaining, or more complex treatment id indicated.

When one primary canine is lost, treatment is needed to prevent or correct a
midline shift.

7. 
Depending on the overall assessment, the dentist can either remove the
contralateral canine or maintain the position of the lateral incisor on the side
of the canine loss using a lingual arch with a spur.

If midline shift has occurred from tipping, the appropriate treatment can be
implemented with a removable or fixed appliance.

If both canines are lost:
1- An active lingual arch for expansion .
2- A passive lingual arch for maintenance.
3- Or no treatment may be indicated.
Maxillary first molars

It is usually diagnosed from routine bitewing radiographs.

Some reports suggest that this painless and often unrecognized condition is
related to a small and distally positioned maxilla as well as steeply angulated
and large permanent molars.

Lack of timely intervention may cause loss of the primary molar and space
loss as the permanent molar erupt mesially .

Because of the frequency of self correction of ectopic eruption,
 a period of watchful waiting is indicated when only small amounts of
resorption are observed

If the blockage of eruption persists for 6 months or if resorption continues to
increase, treatment is indicated.

If a limited amount of movement is needed but little or none of the
permanent first molar is visible clinically, a 20 mil brass wire looped and
tightened around the contact between the primary second molar and the
permanent molar is suggested.

8. 
A steel spring clip separator, available commercially, may work if only a small
amount of resorption of the primary molar roots exists.

These clips are difficult to place if the point of contact between the
permanent and primary molars is much below the cementoenamel junction
of the primary molar.

Elastomeric separators wedged mesial to the first molar also can be used for
this purpose but are not recommended. They have the potential to become
dislodged in an apical direction and cause periodontal irritation.

If this occurs, the separators can be hard to locate and retrieve, especially if
the material is not radiopaque.

If resorption is more sever and more distal movement is required than can be
provided by these simple appliance, the situation becomes more complex.

A useful fixed appliance is a band on the second primary molar, supported by
a transpalatal lingual arch when maximum control is desired, with a
cantilever arm extending distally behind the unerupted permanent molar.

Then a spring or elastomer is hooked from the end of the cantilever to a
button bonded on the molar, generating a force to move distally.
End of this lecture