Space gaining in orthodontics /certified fixed orthodontic courses by Indian dental academy

Space gaining in orthodontics

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com


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Extraction
Expansion
Molar distalization
Enamel stripping
Uprighting of molars
Derotation of posterior teeth
Proclination of anteriors
Distraction osteogenesis


• Contemporary Extraction Guidelines:
– For Class I crowding / protrusion:

• < 4mm of arch length discrepancy
with no vertical discrepancy: nonextraction.
• Arch length discrepancy – 5-9mm
• Non-extraction – transverse expansion
of premolar segment.
• Extraction – any pattern depending
on hard and soft tissues.


• > 10mm : Extract
• 1st choice –
4
4
4
4
4
4
2
2
• 5 5 & 6 6 - rarely satisfactory
• 5 5
6 6


• I] Indications for extraction of 1st
premolars (Tweed and Begg):
• Maximum anterior retraction and camouflage
of Class II div I.
• Less taxing of anchorage – maximum
anchorage.
• Eruptive sequence – space for canines.
• Space discrepancy > 10mm for Class I M.O. –
crowding.


• II] Indications for 2nd premolar
extraction: Nance, Carey, Dewey
and Thompson (Begg)
• Good profile and mild crowding.
• Straight profile and moderate crowding.
• Class II div. 1 dental on class I skeletal with
mild mandibular crowding.
• Mild Class III and mild maxillary crowding Class
III - 5 5 Niwa et al.
• Case of maxillary set back surgery.
• Crowded and out of arch.
• Correction of molar relation.


• III] Indications for incisor extraction:
• Severely crowded mandibular arch –Severe
protrusion.
• Periodontal breakdown.
• Severely fractured.
• Bolton discrepancy.


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Maxillary central incisors:
Caries.
Fracture.
Dilacerated.
Badly impacted.

• Maxillary lateral incisor:
a. Crowding in incisor region with
mesial displacement of root apices of
3 3 www.indiandentalacademy.com

• IV] Indications for 1st molar
extractions (Wilkinson):
• Carious / endo treated/ multifilled.
• Esthetic considerations with properly
developed 2nd and 3rd molars –
large nose and chin – 4 4 dished
face.
• Open bite cases?
• Supraerupted teeth.
• Crowding in premolar region and
incisors in good relation.

• V] Indications for canine extractions:
(Creekmore):
• Periodontally involved.
• Horizontally impacted – tooth
movement?
• Distally tipped/ severely rotated /
grossly displaced buccally/palatally.


• VI] Indications for 2nd molar
extraction:
• Mild –moderate arch length
discrepancy with good esthetics.
• Distalization of first molar.
• Relieve lower incisor crowding.
• Relieve impaction of 2nd premolar.
• Severely carious / ectopically erupted
/ rotated.
• Passed average physiologic age of
eruption and 5 5 are normal – size,
shape and root area.

• VII] Single arch extraction:
– Class II div 1 –
•Perfect lower arch alignment,
but growth expected
inadequate for non-extraction.
• With mild anterior open bite.
•Minimal patient cooperation.
•Vertical growth pattern – no
molar distalization.
•Minimal growth expectation.


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Factors affecting choice of extraction:
Treatment objectives.
Potential stability.
Occlusion.
Esthetics.
Type of malocclusion.
Growth pattern.


Enamel Stripping


Contents

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Definition
Current Trends
Indications
Peck and Peck Analysis
Amount of Enamel Stripping
Methods of Enamel Stripping
Technique
Fluoride Remineralization
Precautions
Advantages
Disadvantages
Controversies
Summary

• Enamel stripping is a method by
which the proximal surfaces of the
teeth are sliced in order to reduce
the mesio-distal width of the teeth.

Definition

• Reproximation – Peck and Peck, 1972.
Tooth reproximation is a clinical
procedure involving the reduction,
anatomic
recontouring,
and
protection of the mesial and/or distal
enamel surfaces of a permanent
tooth.


Individuals with
– Good oral hygiene

Indications

– Class I arch length
orthognathic profiles

discrepancies

with

– Minor class II dental malocclusions (particularly
non-growing patients)
– Bolton tooth size discrepancies
– Arch length discrepancies less than the size of
two premolars
– Peck and Peck
slenderization.

ratio

indicating


need

for


• Harvey Peck and Sheldon Peck in 1972.
• Naturally well-aligned mandibular incisors
possess
distinctive
dimensional
characteristics. These teeth are significantly
smaller mesiodistally and significantly larger
faciolingually,
when
compared
with
average population tooth dimensions.

• It appears, therefore, that tooth shape
(mesiodistal and faciolingual dimensions) is
a determining factor in the presence and
absence of lower incisor crowding.


• Index =

Mesiodistal crown diameter X 100
Faciolingual crown diameter

• Well-aligned mandibular central incisors 88.4 ± 4.3
well-aligned mandibular lateral incisors 90.4 ± 4.8


• Clinical application


– The observed relationship between mandibular
incisor shape and the presence and absence of
mandibular incisor crowding had significant
clinical relevance.
– The MD/FL index provides an effective clinical
method for diagnosing tooth shape deviations
which influence and contribute to mandibular
incisor crowding.
– This data helps in determining whether a lower
incisor is favorably or unfavorably shaped relative
to good alignment.
– The following ranges are employed as clinical
guidelines for the maximum limit of desirable
MD/FL index values for the lower incisors:
Mandibular central incisor --- 88-92
Mandibular lateral incisor --- 90-95

• Clinical application


– Lower incisors within or below these ranges are
considered favorably shaped. Any lower incisor
with an MD/FL index above these ranges,
however, is considered to have a crown shape
deviation which may influence or contribute to
the crowding phenomenon.
– However, an MD/FL index in excess of 100 for any
of the lower incisors represents a severe shape
deviation, characteristic of existing or potential
tooth irregularity.
– Patients whose mandibular incisors have MD/FL
indices above the desired ranges may well be
candidates for the removal of some mesial
and/or distal tooth substance in conjunction with
orthodontic therapy – "reproximation"


Methods of Proximal Stripping

• Two steps:
1. Initial reduction
2. Polishing



1. Mechanical
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Abrasive strips (hand held / motor driven)
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Abrasive disks
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Abrasive linen strips
Diamond coated metal
Safe sided carborundum disks (mounted on
contraangle handpiece)
Perforated diamond coated disk (in an oscillating
handpiece) (Zhong et al, 1999)
Thin double sided diamond disc (Carter, 1989)

Ultrasonic unit using an aluminum hydroxide
paste and special reducing tips
Long thin burs
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Diamond coated
Tungsten carbide (Sheridan, 1985; Lucchese et al,
2001)

1. Chemical
2. Combination techniques


Polishing
• Tungsten carbide burs
• Oscillating Elastrips (fine/ultrafine)
• Sof-Lex XT disks (fine/ultrafine)


• Air Rotor Stripping
• Modified ARS (for anterior teeth)

Techniques

• Combination technique (mechanical
and chemical)


• John J. Sheridan -1985, 1987

Air Rotor Stripping (ARS)

• A technique which enables the clinician to
remove a precise amount of interproximal
enamel to create space, primarily in the
buccal quadrants, for aligning or retracting
teeth.
• Upto 8.9 mm of space can be obtained in
an arch using ARS.


• Align the teeth

The ARS Technique

• Gain an open field
– visual access to the interproximal area.
– a thick separator is useful if an archwire has not
yet been placed.
– if an archwire is in position, a tightly compressed
coil spring between the brackets will prevent the
possibility of lost separators.


The ARS Technique

• By the next appointment, the coil spring
should have opened space so that the
proximal surfaces are clearly visible.


The ARS Technique

• To prevent nicking the papilla during ARS,
place a .020" brass wire between the tissue
and the bur. When placed below the arch
wire, this shield will also retract the lip and
keep the tongue out of the way during ARS.


The ARS Technique

• Robert Lokar (JCO, 2000) suggested the use
of Stim-U-Dent Plaque Removers instead of
brass wire as he found them often clumsier
and too thick for anterior interdental
spaces.


• Removal of enamel

The ARS Technique

– The bur of choice for the initial reduction is a 699L,
a small, tapered crosscut fissure carbide bur with
an extended cutting area.
– Water spray


The ARS Technique

• The ARS bur in an airrotor
handpiece
is
placed
on
the
indicator
wire
and
moved parallel to the
plane of the wire
occlusally or incisally
with a light wiping
motion.
• Because the field is
open, the reduction
can be done on either
or
both
proximal
surfaces.


• Finish and contour with a 135-EF stilettoshaped ultrafine finishing diamond bur.

The ARS Technique

• The enamel surfaces adjacent to the ARS
site should be sculptured so that the tooth
appears natural without an excessively
angular contact area when the spaces are
closed.


The ARS Technique

• Reduce additional contact points on
subsequent visits, working usually from
posterior to anterior in the buccal segments.
After the proximal surfaces of one site are
reduced, the mesial tooth is retracted into
the space by advancing the open coil
spring to the next mesial contact point. This
in turn opens the next ARS site.


The ARS Technique

• As teeth are distalized, ligate them to the
anchor teeth. The archwire need not be
removed— only the ligatures needed to
advance the open coil spring along the
wire.
• The coil spring can be stretched along the
archwire if more force is needed to
separate the teeth at subsequent ARS sites.


The ARS Technique

• A modified ARS procedure uses a reducing
bur in an air-turbine handpiece in
combination with a metal abrasive strip.

Modified ARS

• This modification is useful for the removal of
smaller amounts of interproximal enamel
and is usually reserved for the lower anterior
teeth, where thin interproximal enamel
permits less mesiodistal reduction.


Modified ARS

• The interproximal enamel is reduced with a
699L stripping bur on the lingual and facial
surfaces until the contact area is a knifeedge of enamel.
• This enamel is then removed with the handheld abrasive strip.


Modified ARS

• The advantage of this two-stage procedure
is that the air-rotor reduces the bulk of the
enamel so that less force is required with the
hand-held abrasive strip.
• This procedure is most efficient before or
after treatment, when the teeth are not
mobile.


Combined Technique

• Advocated by V. P. Joseph, P. E. Rossouw
and N. J. Basson after their study on
‘Orthodontic microabrasive reproximation’
(AJO, 1992)
• Combined mechanical
stripping method.


and

chemical

Combined Technique

• Chemical stripping in restorative dentistry –
18% HCl – for removal of white spot lesions
(upto 100 µm).
• But it is caustic, hence in orthodontics 37%
phosphoric acid can serve as a good
alternative.


Combined Technique

• In this technique, the mechanically reduced
proximal surface is treated with phosphoric
acid.
• The furrows created by the mechanical
reduction are more or less flattened by this
acid etch procedure producing a surface
which
can
better
‘heal
itself’
by
remineralisation.


Combined Technique

• Artificial remineralization of the etched
enamel surface is possible as shown by
crystal growth. A low concentrate calciumfluoride solution produced this growth in a
time dependent fashion.


Fluoride Remineralization

• Fluoride Remineralization
– Any stripping procedure removes the cariesresistant, fluoride-rich layer of surface enamel.
This
can
readily
be
reestablished
with
commercially available, office-applied fluoride
rinses.


• Though proximal stripping is a procedure restricted to the
enamel, extra care must be taken while performing the
procedure in young individuals as they have larger pulp
horns hence are more likely to develop sensitivity.

Precautions

• If the procedure is done properly and the teeth are
contoured to acceptable morphology and moved into
arch form, they appear so natural that there is a danger of
repeating the ARS procedure if more space is needed. To
prevent this situation, chart all ARS and combination
technique sites, noting the date and approximate amount
of reduction.


• Ledging of the enamel should be avoided.

Precautions

• Use separation. In broadening the contact areas, one
should avoid slice cuts which may produce an unstable
arch form. Adequate separation allows for consideration
of arch curvature where slightly more reduction of enamel
may be obtained on the lingual than on the labial areas of
the proximal surfaces.


Advantages of Stripping

1.

Possible to avoid extraction in borderline
cases. Especially beneficial when treating
adult non-growing patients.

2.

A more favorable overbite and overjet
relation can be established by eliminating
tooth material excess in either of the
arches, improving anterior function in the
mutually protected occlusion.

3.

Begg has stated that reduction of the
widths of the upper and lower incisors and
canines
for
orthodontic
purposes
conforms more closely to basic biologic
requirements than does orthodontic tooth
extraction.


Advantages of ARS

1.

Removal
of
precise
amount
of
interproximal enamel to create space,
primarily in the buccal quadrants, for
aligning or retracting teeth.

2.

In selected cases, ARS can resolve
significant differences in ratios of tooth size
to arch length, and the technique can
become an alternative to extraction or
expansion. Upto 8.9 mm of space can be
obtained in an arch using ARS.


Advantages of ARS

3.

ARS can create substantially more space
than is usually obtained by conventional
interproximal reduction procedures.

4.

The lower incisors have less proximal
enamel than posterior teeth, and lower
incisor irregularity generally increases
naturally at an age when most
orthodontic cases are in retention.
Anterior interproximal reduction of more
than 2-3mm would virtually eliminate the
option of further reduction to eliminate
post-treatment crowding, simply because
there would be little if any enamel
remaining on the lower incisors.


5.

Advantages of ARS

In lower incisor extraction cases, a tooth
material disproportion is created between
upper and lower anteriors leading to
unfavorable overjet. Stripping in the
upper anteriors only can lead to
unesthetic
shapes.
ARS
helps
in
redistributing the tooth material reduction
(Sheridan and Hastings, JCO 1992).


Disadvantages of Stripping

1.

The technical concern in reproximation procedure
is the precision removal of substantial interproximal
enamel, following which the completed reduction
site should have smoothly finished enamel walls
without undercuts, and the reduced surfaces
should be reshaped to resemble the original
interproximal morphology.

2.

Space opening occurs infrequently in an ARS site
and the majority of the space closes during
retention, but it is a possible long-term effect of
the ARS procedure.


Disadvantages of Stripping

3.

Irreversible. Hence should be done with
utmost caution and responsibility.

4.

The technique should be selectively used
on patients with good oral hygiene and
low caries susceptibility.


Controversies

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• Amount of stripping ?

Controversies

• Best method ?
• Susceptibility to Caries and
Periodontal Disease ?


• Enamel Stripping is a skilful procedure which
when judiciously used can prove to be a
boon to the orthodontist.

Summary

• All that is required is the correct knowledge,
some skill, and confidence.
• Von der Heydt : "Dental crowding is
amenable to a corrective procedure which
is too seldom undertaken despite the
simplicity
and
effectiveness
of
the
procedure. A little more knowledge and
courage to offer this to the public would be
of value to all concerned."

Thank you
For more details please visit


Space gaining in orthodontics /certified fixed orthodontic courses by Indian dental academy

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