interproximal reduction of enamel as part of orthodontics

NTERPROXIMAL REDUCTION
PROF DR MAHER FOUDA
FACULTY OF DENTISTRY MANSOURA EGYPT
AS PART OF ORTHODONTICS

Interproximal reduction (IPR)
involves the selective removal of
enamel proximally to create
space for tooth
Movement.

Stripping is commonly used in cases requiring
additional space to align the teeth where there is
moderate crowding and to correct tooth size
discrepancies, as well.
Interproximal stripping is about to
be performed on this temporary
tooth to improve occlusion.
moderate
crowding

Several methods utilizing mechanical or chemical
means, or a combination of both, have been presented
as safe and effective methods of choice for enamel
reduction.

Thus, the use of perforated diamond coated discs,
utilized in conjunction with air-rotor or micromotor
handpieces have all been proposed
perforated diamond
coated discs

Also, the use of diamond-coated strips adapted to hand
pieces or manually used have also been proposed
diamond-coated strips

diamond burs
also, the use of diamond burs utilized
in conjunction with air-rotor or micromotor
handpieces,
have all been proposed.

Also, the use of tungsten carbide burs utilized
in conjunction with air-rotor or micromotor
hand pieces, have been also proposed
tungsten carbide burs

Acid etching of enamel by means of 37% ortho
phosphoric acid can be used in combination with
mechanical stripping, to enable faster stripping
procedures.
FOUR HANDED GUARD

Stripping leaves a relatively rough enamel surface and must
be followed by polishing in every stage, which restores
appropriate anatomical form to the tooth and reduces
roughness of the interproximal surfaces.
diamond-coated finishing strips

For this purpose there have been utilized fine and
ultrafine Sof-lex discs, or fine pumice media,and
polishing strips used in handpiece or manually
The teeth are treated with
topical fluoride application
following reduction of the
enamel

fine and ultrafine diamond burs may assist the
operator in achieving a smooth contact area, which will
presumably prevent excessive plaque accumulation
Tungsten Carbide
Finishing Burs Tapered
Point
diamond burs

Various authors have deemed a
reduction by 50% of the original enamel
coat to be acceptable.
.

It has been suggested that reduction should not exceed 0.2-0.5 mm of
surface
from the incisors, 0.3-0.5 mm from the canines and 0.5- 0.6 mm from
posterior teeth of upper or lower jaw
A and B, Woman (age, 31 years) with mild Class II malocclusion and mandibular
crowding at the start of treatment; C-E, IER on all teeth mesial to the first molars; F-H,
6 years after completion of orthodontic treatment with lingual retainer bonded to 6
anterior teeth. Note the interproximal caries lesions (grade 1) on the maxillary left first
and second premolars (arrows). There is also a small caries lesion (grade 1) on the
mesial aspect of the maxillary second premolar.

Following stripping, the surface properties of enamel
are altered, with significant changes in roughness,
something which may lead to plaque accumulation
and increase the susceptibility of proximal enamel
surfaces to demineralization and dental caries

Review of the available literature shows that
smoother enamel surface is obtained with the use
of diamond-coated discs or strips or 8-straight
blade tungsten carbide burs, followed by polishing
with Sof-lex discs.
diamond-coated discs
diamond-coated
strips
8-straight blade
tungsten
carbide burs
Sof-lex

Enamel reduction with 37% orthophosphoric
acid or rotary instruments at high speed
without surface polishing induces severe
enamel irregularity
stripping strip with polishing
system and 35%
orthophosphoric acid

Many studies with scanning electron microscopy
demonstrated that, regardless of the polishing and
finishing method applied, furrows of 10-30 μm depth
remain on enamel surface, leading to plaque retention and
enamel demineralization

polishing enamel after stripping achieves similar
morphological characteristics and smoothness as
intact enamel
Perforated Diamond Strips are designed for complete control during
interproximal reduction, shaping, and contouring. Strips allow easy
access and precise manual enamel reduction resulting in a smooth,
natural finish..

Perforated strip design assists in debris removal,
provides improved visibility, control, and flexibility; made
of stainless steel to resist breaking and stretching.
Perforated Strips are color coded for grit selection; blue
for medium, red for fine, and yellow for super-fine

Polishing with finer abrasives is necessary to achieve a
subsequent reduction of grooves caused by coarse
abrasives. Polishing the enamel after reduction does not
help achieve the same morphological characteristics as
with intact enamel but various attempts have been made
to achieve a smooth surface..

Polishing can be done with fine grit diamond bur,
Sof-Lex discs, pumice media, and use of proximal
sealant after interproximal reduction.
fine grit diamond bur

GC Fuji TRIAGE is the glass ionomer sealant and surface
protectant. It keeps patients' teeth cavity-free. There is no isolation
or bonding agent required. It works in a moist field. It is used as
sealing over immature enamel or non-cavitated lesions. The self-
bonding, high fluoride releasing GC Fuji TRIAGE creates a strong,
acid-resistant fused layer
GC Fuji TRIAGE®
Glass Ionomer Sealant & Surface
Protectant
proximal sealant

Short-term use of fluoridated dentifrice or topical
gel also reduces the penetration of the lesion but
not to the extent of a non treated unabraded
surface
topical fluoride gel
fluoridated dentifrice

It is generally believed that these lesions will
recover at some extent through natural
remineralization with saliva even in a period of 1-9
months after the orthodontic appliances removal
and oral hygiene is restored.
Super-Snap Polystrip Dental
Finishing Strip

The processes of natural wear and attrition
that produce a smooth surface around the
contact point may also play a significant role
Perforated Diamond Finishing
Strip

Although irregularities remained after stripping
which might facilitate plaque and bacteria retention
and caries development, there is no inevitability
about this becoming a clinically significant event.
FlexiStrips
Interproximal Finishing and Polishing Strip

Many follow-up studies indicate that there is not a
significant relationship between enamel stripping
and development of interproximal caries on
anterior or posterior teeth, for a study period of 1-
10 years following the application of the technique
Finishing and Polishing Strips

Significant preventive measures as good oral hygiene,
regular prophylactic checkups for caries and fluoride
application should be followed after IPR
Besides being one of the safest, easiest and most effective methods
of delivering topical fluoride, especially to uncooperative
children, Duraflor 5% Sodium Fluoride Varnish is formulated to
provide quick relief from hypersensitivity for up to six months.
.
Duraflor Sodium Fluoride Varnish

Duraflor Sodium Fluoride Varnish
It has less ingestion.
it needs no tray needed
No effect on bonding of ortho brackets.
Duraflor sets on contact with saliva and stays
on teeth up to six hours for enhanced fluoride
uptake.

Many authors have suggested the application of fluoride
containing products immediately after stripping in order to
prevent further mineral loss and promote remineralization

The technique that using transparent aligners without the
employment of conventional orthodontic appliances for
moving teeth, indicated that the frequency of stripping in
routine orthodontic practice increased as a method of
generating space by enamel reduction

Interproximal reduction is a technique that was first
introduced in the 1940s by Ballard for use on anterior
teeth.

Natural
slenderization’ had, however, been described by GV
Black at the beginning of the 20th century.

This concept
was later echoed in 1954 when Begg described
the natural interproximal abrasion and tooth
movement that
occurred in Stone Age man as a result of a
primitive, rough diet.

IPR techniques changed significantly following the
research and recommendations made by Dr. Jack
Sheridan
in 1985, which included the concept that premolars and
molars could also be reduced on their mesial and distal
surfaces.

Subsequent developments by many researchers led to the
techniques and protocols used today for IPR
(also known as slenderization or cosmetic tooth
recontouring).

IPR can be performed in conjunction with traditional
orthodontics or clear aligners, with treatment planned by
the clinician or, in some cases, through lab services that
utilize digital technology.

Basics of IPR
IPR is a safe and effective method to create space for
orthodontic tooth movement where mild or moderate
crowding exists, particularly.

IPR is useful also suitable
for recontouring individual teeth

Cosmetic tooth contouring is to improve the
shape of the teeth and enhance the overall
appearance of the smile

tooth contouring is done to make minor aesthetic
changes to the size, length, surface, or shape of the
teeth.

Tooth contouring can be used to correct:
1-Slight tooth overlapping
2-Irregularly shaped teeth
3-Teeth that appear too long or too large
4-Dips or other imperfections on the tooth surface
5-Chipped or cracked teeth
6-Adjacent teeth of unequal lengths
7-Teeth that look too pointed

Treating Crowding with IPR
1-Where up to 8 mm of space is required within
an arch

1-Where up to 8 mm of space is required within
an arch
(a)Pretreatment mandibular occlusal view. (b) Mandibular initial
archwire: 0.016-inch NiTi, interproximal enamel reduction; class 3
elastics. (c) Mandibular finishing archwire: 0.017 × 0.025-inch
SS. (d) Three year posttreatment mandibular occlusal view

When the crowding is less than 5 mm, stripping or
mesiodistal enamel reduction is the best choice.
(Zachrisson 2005; Zachrisson et al. 2007)

Stripping is never performed before brackets are
placed since the space gained could be easily lost. The
shape of the anterior teeth is important; those with a
triangular shape make it easier to perform stripping

Bjorn Zachrisson (Zachrisson 2005; Zachrisson et
al. 2007) demonstrated that it is recommendable to begin
on teeth that are better positioned in order to avoid
unnecessary stripping or steps that are very difficult to
correct
Patient in whom interproximal
enamel reduction (IER) was
performed before treatment to
alleviate crowding; only very
limited tooth movements will be
required and no excessive space
will remain if the procedure is
carried out with due care.

Treating Crowding with
IPR
2-As an adjunct for clear aligners.
.

2-As an adjunct for labial fixed
orthodontic appliances

2-As an adjunct for lingual fixed
orthodontic appliances

3-In combination with other methods used to
create space, (e.g., rapid palatal expansion(RPE)
and distalization.
rapid palatal expansion distalization

proclination
3-In combination with other methods used to create
space, (e.g.,
proclination .

3-In combination with other methods used to create space, (e.g.,
extractions
Intraoral images of the Class II
elastics used during the initial
treatment phase
Pretreatment ClinCheck
treatment Plan

Individual Tooth Recontouring with
IPR Can be Performed
When <50% of mesial or distal enamel thickness
reduction would be required
(maximum amount varies by tooth type)

IPR should be performed parallel with the
long axis of the tooth. Otherwise,
IPR would result in excessive removal of
enamel in some areas, gouging and
the creation of ledges

Advantages of IPR
. May avoid extractions
• Less invasive
• Shorter distances for individual tooth movements
• Reduces the risk of residual space where extractions
would provide more space than is required
Due to their
increased
mesio-distal
width, the
maxillary
lateral
incisors in
this case were
selected for
IPR as a
means of
gaining space
to alleviate
crowding.

Advantages of IPR
• May avoid lengthy arch
expansion/distalization/tooth proclination

• Acquisition of space can be staged during treatment
• May reduce treatment time
• Opportunity to simultaneously adjust teeth with poor
contours or poorly-contoured restorations
Advantages of IPR
Triangular shaped teeth with unaesthetic gingival contour. Alignment without
IPR would result in increased show of black triangles due to their
Triangular shaped
teeth

• Improves post-treatment stability and stable
contact points by flattening contours
• End result may have roots more parallel than
with other methods and less relapse
Advantages of IPR

It is very important to measure the space gained by
Interproximal Reduction (IPR)through using the
Gauge Measure ,Sheridan space measuring gauge
and digital Boley gauge

Interdental Space Measuring Gauge The Sheridan
Space Measuring Gauge is a multipurpose instrument constructed from
laser-etched stainless steel that is impervious to alteration from
conventional sterilizing mediums. The gauge consists of a series of
cylinders, of progressively increasing diameters, which can measure
natural or created interdental space from .75 to 3.0mm in increments of
.25mm. The diameter of each cylindrical section of the gauge is
correlated with the indication on the handle.

The Sheridan Gauge enables the clinician to: (1) Measure
naturally occurring generalized spacing (2) Measure and
chart the amount of enamel that may be removed during
stripping procedures (3) Aid in the establishment of
parallel proximal walls during enamel reduction (4) Tuck
ligatures with the knurled tip of the large end (5) Obtain
indications of the severity of periodontal pocket depth

Indications & Contraindications For
Treatment
Indications
IPR offers a proven, relatively noninvasive method for creating space.
Main indications for IPR:
dental crowding • invisible lingual orthodontics – Incognito System

Indications
1-Crowding of the mandibular or maxillary
incisors
2- Class I arch-length discrepancies
3- Class II minor malocclusions

(1–5) A 29-year-old female patient with crowding in the lower arch, crossbite
of the lower right canine and midline deviation. before treatment. (6) Initial
panoramic X-ray. (7–11) Final results. Intraoral X-rays after slenderizing and
reproximation: lower right molars; lower right canine; lower incisors; lower

Indications
4- Class III minor malocclusion
5- Recontouring of teeth 6-Traumatic occlusion

7-Tooth size discrepancy
Fixed appliances placed for a short period. (C) After aligning,
access to interproximal areas is facilitated. (D) Interproximal
enamel reduction is completed. (E) Further alignment
improvement is achieved. (F) End of treatment, bonded lingual
retainer in place.

8- Correction of the Curve of Spee (the anteroposterior
curve determined) by the occlusal alignment of the teeth
Indications
Flattening deep curves of Spee increasing arch length
and labially proclines the incisor teeth.

Indications
7-Presence of poor gingival contours and pre-treatment
‘black triangles’
When the teeth are triangular in shape, they connect with one another
at the chewing surface but not near the gum line, leaving a larger gap
between teeth. Furthermore, black triangles often develop after
orthodontic treatment (braces) is completed, especially in adults. This
is a natural consequence of alignment correction, and often cannot be
avoided. Another common cause is gum recession and bone loss. If
the gums surrounding the teeth begin to recede due to gum disease
or bite-related traumas, these black triangles begin to appear. If left
untreated, they will grow larger over time.
After IPR and minor
tooth movement
iangular shaped incisors

Contraindications
1-Required reduction exceeds the recommended limit
per arch or tooth type
2- Hypersensitivity
3- Enamel hypoplasia

Contraindicatio
ns
4- Small teeth

5- poor oral hygiene :It is important to remember
that this procedure can be performed if the patients
have good oral hygiene. Otherwise, interproximal
cavities will be the result in a very short period of
time.

6- Rectangular-shaped/square teeth, as these require
substantial IPR to gain space and produce broad
contact surfaces; may also cause food impaction and
reduced interseptal bone

The ovoid-shaped teeth will position the contact
point in a gingival direction. The’’best’’ mesio-distal
inclination is the objective here..

To obtain a more harmonious smile, the
orthodontist will do a light stripping in
order to soften the peripheral curves
and to harmonize the contacting
ovoid-shaped teeth

6- Rotated teeth that preclude proper access to the
contact area even with the use of separators.
Correction of anterior open bite
Invisalign Treatment

.Derotation should be done before IPR
Rotated teeth that preclude proper
access

Mildly Rotated Teeth
It is to decide whether to use the dual-coated diamond OS
discs or the single-sided, diamond-coated OS discs. In
this case, the amount of tooth rotation is minimal and the
teeth are not overlapped. This is ideal for using the dual-
sided, diamond-coated OS discs for rapid removal of
interproximal enamel on both adjacent teeth
simultaneously

In cases where the contact is large and access is
difficult, using progressively thicker strips to open
the contact significantly is advantageous before
beginning with the OS discs
Mildly Rotated Teeth

When interproximal reduction is necessary between
overlapping teeth, removing the appropriate amount of
enamel on each of the adjacent teeth can be more
challenging.
overlapping teeth

overlapped teeth preclude IPR, until using
separators which create access for IPR.

Simply passing a dual-coated diamond disc between
teeth positioned like these would result in uneven
reduction and anatomically mutilated contours
overlapping teeth
dual-coated diamond disc Oscillating Segment Disc

In clinical scenarios such as this, the single-sided,
diamond-coated OS discs are appropriate. In this case,
the amount of IPR indicated is 0.3 mm, which means that
0.15 mm needs to be reduced from each tooth.
overlapping teeth
(0.30mm) Oscillating Segment Disc

Traditionally, IPR/stripping has been accomplished with
diamond strips or rotary discs. Because diamond strips can
jam or be impeded by inadequate space for grinding
movements, rotary discs are often used instead. The discs
have their own drawbacks, however: Like the risk of
damaging, the soft tissue and they can obstruct operator
vision, particularly when using a disc guard.
(0.30mm) Oscillating Segment
Disc

Some authors recommend the use of diamond
single-side strips because a better control is
achieved. The use of burs or disks could produce
more and unfavorable loss of enamel

In cooperation with Professor Dr.
Jost-Brinkmann of the Berlin
Charité Dental Hospital, Komet
has developed the 60˚,
oscillating OS segment disc, a
reliable solution for safe,
efficient IPR. With a radius of
just 1.4 cm and a pivoting angle
of 30˚, the OS disc does not
require a disc guard, and it is
ideal for use in exceptionally
narrow areas. Unlike full-radius
rotary discs that require disc
guards and that have diameters
of up to 2.2cm, the OS disc
offers optimal vision as well as
excellent grinding efficiency
(0.30mm) Oscillating Segment
Disc

What is unique about this IPR system is that each
honeycombed-designed disc does not rotate 360°, but
merely oscillates 30° (15° in each direction). The
oscillating motion is superior to complete rotary
movement in that binding or jamming in the interproximal
contact is minimized and accidental rotation (catching and
running) into the adjacent hard or soft tissue is less likely
to occur
Komet OS 30 Oscillating Handpiece

The diamond-coated OS discs are arranged in increasing
thickness (0.2 mm to 0.4 mm including reduction by
subsequent polishing) and are sequentially used from the
thinnest to the thickest until the target amount of enamel is
reached.

the kit contains discs that have diamond coating on one
or both sides. A single-sided coated OS disc COULD BE
USED to carefully reduce a single tooth when mild
overlap or rotation does not permit a straight pass
interproximally
To be used in the oscillating Komet-contra-angle
OS30--Set containing oscillating segment discs

The single-sided coating is available in 0.15-mm to 0.2-mm
thickness on the outside (away from the shank) or the
inside (toward the shank) so that either a “push” or “pull”
motion may be used as dictated by the arrangement of the
teeth to be reduced. Also included in the kit are discs in
each thickness that are diamond-coated on both sides.
These OS discs are best used when crowding is less severe
and simultaneous interproximal reduction of both adjacent
teeth is possible

The OS30 handpiece should be used after the initial contact
is opened with diamond-coated metal strips and should
operate at a 1:1 setting. This setting permits an oscillating
speed of 5,000 oscillations per second and should be used
with sufficient water spray for heat reduction. The OS discs
are designed to enter the contact from the occlusal aspect
of the contact and the honeycombed design permits clear
visibility as the reduction occurs
The segmented discs are designed for
use in the oscillating Komet contra-
angle OS30

Compared to the other rotary cutting discs with a full
radius of up to 2.2 cm in diameter and a disc guard, the OS
Discs offer the best features of interproximal enamel
reduction in hard-to-reach areas. The honeycomb design of
the OS Discs provides optimal vision and excellent
grinding efficiency leading to absolutely convincing results

To minimize the risk of removing excessive enamel
substance, the tooth width should be measured with a
sliding caliper before use and also during the enamel
reduction . Alternatively, a thickness gauge can be used to
measure the thickness of the removed enamel
thickness gauge
Improper contour visible on radiographs, accompanied
by incomplete space closure

Before stripping, the interdental contact
should be eliminated using the KOMET
diamond strips with honeycomb design (the
yellow strip should be used first because it
is the thinnest).

According to the amount of enamel to be reduced, the
corresponding segment disc type is chosen: OS Discs
with medium grit (blue ring) for higher substance removal
and with fine grit (red ring) for less substance removal .
The OS Discs are used in subsequent order (from the
thinnest to the thickest). The OS Disc is moved in an
occlusal to cervical direction, and the treated teeth should
be aligned in a straight line

After breaking contact with a diamond-coated metal
strip, simply insert the 0.15-mm OS disc with the
diamond coating facing the shank and position it
against the mesial aspect of left central incisor tooth.
overlapping teeth
diamond-coated metal strip

With water coolant, use a sweeping motion to begin
removing enamel and enter the contact area from the
facial aspect . The OS discs have the flexibility of
common diamond discs and are optimal for shaping and
contouring as well as interproximal slicing. The clinician
should be careful not to jam the disc
overlapping teeth

When the 0.15-mm disc can pass freely between the teeth
at the appropriate angle, insert the 0.15-mm disc into the
oscillating handpiece with the diamond coating facing
away from the shank..
overlapping teeth
The completed IPR0.15-mm disc

Position the os disc against the right central incisor
tooth and with a sweeping, pushing motion, begin
reduction of the mesial enamel. Again, be sure to shape
and contour the tooth.Oncecontact is opened an
additional 0.15 mm is removed
overlapping teeth
The completed IPR

A 0.3-mm reduction gauge confirms the appropriate
amount of reduction.
overlapping teeth

Only handheld strips are recommended to break
contacts with overlapping teeth to avoid damaging the
enamel..
overlapping teeth

Although minor overlap may not make use of thin burs
physically impossible, their use may cause
damage to the adjacent enamel and is not recommended
overlapping teeth
6 months after treatment
very mild crowding and
central incisors overlapping
in the upper anterior sextant
After a light interproximal
reduction (IPR), or stripping, a
lingual 0.014 NiTi arch was
applied
before debonding

lower anterior teeth , interproximal stripping should be
avoided, as it will lead to quick bone loss and papilla recession
causing
long clinical crowns and triangular spaces apart from sensitivity on
exposed cementum.
Perils (risks)of inter proximal stripping
If the roots of adjacent teeth are too close as is usually the
case in
Perils of inter proximal stripping

Contraindicatio
ns7- Large pulp chambers (young patients)
8- Major crowding if in the absence of
extractions/distalization/other space-gaining methods
9- Prior IPR, if additional IPR would exceed the recommended
limits for removal of tooth structure

IPR should not be performed if patients (or parents/legal
guardians) have not signed an Informed Consent
Form confirming acceptance of the recommended
treatment.
Informed
Consent

IPR Methods
IPR may be performed manually
or mechanically.
Manual options include:
1. Handheld strips

2. Files used with manual holder
IPR
MethodsManual options
include:

Mechanical options include:
3. Files used in an air-driven contra-angle handpieces
IPR Methods

4. Discs mounted on a straight slow-
speed handpiece (anterior use only)
Mechanical options
include:
IPR Methods

The use of flexible diamond-coated discs in a straight
handpiece or in a latch-grip attachment has been used in
performing IPR by some clinicians.
The Danger of Rotary Discs

Because these discs rotate 360° (often at 35,000 to 40,000
rpms), if they become jammed in the contact, the risk of
the disc rotating out of control and rapidly ejecting into the
surrounding tissue is extremely high.

Additionally, achieving the proper angle of
approach with rotary discs can be difficult
and irreversible tooth damage can result .

Mechanical options include:
IPR Methods
5. Burs mounted in a high-speed handpiece
(Air Rotor Stripping or ARS)

Avoiding Potential Complications
Enamel Ledges
Black Triangles
Enamel ledges are the result of tooth gouging during
IPR and then require use of a bonded resin for
resolution.
Ledging is avoided by taking care to perform IPR parallel
with the long axis (versus vertically and perpendicular
to the occlusal surface). Ledging is unlikely to occur
with the use of manual strips.
Enamel
ledging on
radiograph

Black Triangles
Black triangles result in poor esthetics. They can occur if
IPR is performed on teeth with inadequate distance
between the interproximal contact point and the upper
margin of the bone crest. The recommended distance is
4.5 mm to 5 mm.
1) Tarnow et al. (1992) evaluated the relationship between the distance from the
interdental contact point to the bone crest and the presence or absence of
‘black gingival triangles’. (2) The height of the interdental papilla should be 4.5
mm

Black gingival triangles do not always appear due to an
increase in the distance between the contact point and
the bone crest. , a black gingival triangle can appear as
a consequence of a bracket malpositioning with respect
to tooth inclination. In this case, the bracket position
should be corrected and slenderizing should not be
carried out. In these cases, an ‘occlusal black triangle’
can be observed on the other side of the tooth and the
periapical X-ray will show that the roots are not parallel
Black
Triangles

Black
Triangles
Black triangles can also occur when IPR is performed on
triangular-shaped teeth, which have a relatively long
distance from the bone crest to the interproximal contact
point. Once this distance is >5 mm, the interproximal
papilla may be absent, resulting in a black triangle.
Triangular shaped teeth with unaesthetic gingival contour. Alignment
without IPR would result in increased show of black triangles due to their
morphology. Tooth shape should be evaluated at the diagnostic stage and
the need for IPR to address black triangles as well as to produce more
stable contact points should be planned and communicated at the outset

Scheme of a case with
‘black gingival
triangles’ due to the
triangular teeth
Cases with negative
dentoalveolar discrepancy
are treated with
slenderizing and
reproximation
Cases with positive
dentoalveolar
discrepancy are
treated with aesthetic
restorations.

There is no relation between dental shape and
the enamel thickness , therefore the amount
of possible slenderizing does not depend on
the dental shape; however, minimal grinding
of triangular and barrel-shaped teeth will
generate considerable space in the dental
arch.

According to Andrews (1989), if the teeth are tipped
mesiodistally, they occupy more space in the dental arch
than teeth in a more vertical position, but Bennett and Mc
Laughlin (1997) emphasize that this fact is more true for
rectangular teeth than for other tooth shapes . This is why
significant tooth uprighting as a solution for a mild
negative discrepancy is possible only in rectangular teeth
Only the rectangular shape has an important influence on the space
occupied by a tooth in the dental arch, in relation to its inclination.

According to Steiner, incisal protrusion allows us to obtain
double space, i.e. the discrepancy is reduced by 2 mm for
every 1 mm of protrusion.

With slenderizing and reproximation, the contact point
comes closer to the crest of the interdental septum
A 5° torque increase without
protrusion allows increase of 1
mm of space in the arch
Over-extended crowns and
fillings.in such cases, slenderizing is
indicated to obtain normal
tooth shape and dimensions

Poor Contouring
Poor contouring and square/flat appearance’
A-NARROWING THE CURVATURE OF LABIAL SURFACE (CENTRAL PROMINENCE
B-ADJUSTING THELATERAL PROMINENCETOWARD THE CENTRE

Care must be taken to protect the lips, tongue and
gingivae during IPR – for example with a mouth
mirror, and in
the case of discs by using a protective shield
protective shield
and wedgeprotective shield

Excessive Interproximal Reduction results in
residual space
If too much enamel is removed, residual space at the end
of treatment can result in potential esthetic problems
and food impaction (and possibly necessitate additional
orthodontic treatment or cosmetic restorations).

A, Teeth are separated and gingival tissues are protected with WedJet . B,
A “honeycomb”-type disc in a reduced slow-speed handpiece is used to
reduce the mesiodistal widths of the teeth, removing 0.2 to 0.5 mm of
enamel. C, A cone-shaped diamond rotary instrument is used to create
smooth and round line angles, restoring anatomical contours. D, After the
procedure, spaces are evident between all incisors
THE WEDJET PROTECTOR

The amount of enamel that must be removed from
each side of the tooth by stripping is only 0.25–0.50
mm in total, and the dentin will not be exposed, of
course. The total maximum amount of stripping
recommended is 4 mm in the upper anterior teeth
and 3 mm for the mandibular incisors

Treatment
Planning
Overview
Treatment planning includes:
• Full medical and dental history
• Full examination, radiographs and
accurate impressions for study
models
• Measurements and assessments

Treatment Planning
Accurate Measurement & Assessment Must be
Performed
The following measurements and assessments are
required during treatment planning:
Inter-arch relationship: position of the maxillary and
mandibular arches relative to each other

Treatment Planning
Performed
Relationship between the upper and lower
incisors

Treatment
Planning
Performed
Width of the teeth at their broadest point

The mesiodistal width of the maxillary incisors has a
major effect on the amount of possible mandibular
anterior slenderizing. If the maxillary central and lateral
incisors are oversized and the mandibular incisors are
not especially large, mandibular anterior slenderizing
should not be performed alone as this would increase the
tooth size discrepancy. It is possible in such cases to
slenderize in both the maxillary and mandibular arches
Width of the teeth at their broadest
point

Treatment Planning
Performed
Width of arches

Treatment Planning
PerformedWidth of roots relative to the widths of the
crowns of the teeth

Distance between the bone crest and contact
points:
• Performed by sounding the bone from the base
of the contact point – lengths of 4.5 mm to 5
mm will allow the papillae to fill the spaces.
Treatment Planning
Performed

Larger distances usually result in incomplete
papillary fill causing black triangles and poor
esthetics
Black triangle pre-treatment
Note: The presence of parafunctional habits such as lip
chewing, digit sucking, nail biting or tongue thrusting
must be assessed and if present these habits should be
resolved prior to starting treatment.

Accurate Measurement & Assessment Must be Performed
Treatment Planning
Thickness of the enamel
Observed by assessment of radiographs
Must consider tooth type, as this influences the
thickness of the enamel

Enamel thickness
some researchers, in order to quantify dental tissues,
have used lateral radiography and medical computed
tomography . However, the previously mentioned methods
of visualization have been demonstrated to result in
inaccurate measurements of enamel thickness

Three dimensional (3D) dental radiography and especially
Cone Beam Computed Tomography (CBCT) imaging is an
important diagnostic adjunct to the clinical assessment of
the dental patient, presenting many advantages and
providing multiple head and neck applications
Enamel
thickness

The advantages over the conventional CT are the lower
levels of radiation, lower operating time and cost, high
resolution imaging of hard tissues and availability in
smaller dental offices.
Enamel thickness

The main disadvantages are inferior visualization and
differentiation of soft tissue, streaking metal artifacts and
the effect of patient motion on the resulting image
sharpness, caused by heartbeat or breathing , even
though image capturing is performed in apnea conditions.

Studies have demonstrated that the enamel thickness
around teeth is similar in incisors, cuspids, molars, and
premolars. A study by Hall et al. demonstrated that
mandibular lateral incisors have thicker enamel than
central incisors. Enamel thickness of the lower central
incisor was determined: 0.77 mm +/– 0.11 mm on the
distal and 0.72 mm+/– 0.10 mm on the mesial. The lower
lateral incisor measured 0.96 mm +/– 0.14 mm on the
distal and 0.80 mm +/– 0.11 mm on the mesial.
Enamel thickness
A and B are the mesial and distal
enamel thickness measured from
a to b; a=height of contour,

The thickness in premolars can be well over 1 mm. The
minimal enamel thickness, and not the average values,
must be taken into account when determining the
enamel quantity that is going to be removed, since it is
not possible to know which teeth present minimal
thickness.

There is no relationship between dental size and enamel
thickness; therefore, macrodontic teeth should not be
stripped more than microdontic teeth (although
aesthetically it is better to carry out the slenderizing on
macrodontic teeth).

Enamel thickness is slightly greater in the contact
point, gradually decreasing in thickness toward the
cementoenamel junction. The enamel is slightly thinner
in distal than in mesial surfaces. In upper cuspids and
lower second bicuspids, these differences are greater.
The exceptions are upper lateral incisors, whose
thickness is slightly greater distally

Treatment Planning
Accurate Measurement & Assessment Must be Performed
Tooth size discrepancies, using the Bolton Analysis

Note: The presence of parafunctional habits such as lip
chewing, digit sucking, nail biting or tongue thrusting
must be assessed and if present these habits should be
resolved prior to starting treatment.

The Bolton Analysis is used to identify tooth size
discrepancies. ‘Oversized’ teeth can be good candidates
for IPR as this corrects the discrepancy and creates the
space required for tooth movement..

Therefore,
identifying these discrepancies during
treatment planning is important. In addition,
consider recontouring
over-dimensioned restorations and
performing IPR on proximal restoration
surfaces (as this preserves
enamel).
Bolton Analysis

However, observe the upper laterals . They do appear
small, but are they too small? It would be an unpleasant
surprise for all parties (referring dentist, orthodontist
and patient) to discover that unanticipated additional
treatment (e.g.; upper lateral veneers, lower anterior
IPR) would be necessary to achieve the best result. In a
case like this, calculating the Bolton ratio prior to
treatment does provide valuable information

Either the Anterior Bolton Index (ABI) or the Overall
Bolton Index (OBI) (also known as the First-
Molar-to-First-Molar Bolton Index) may be used

Bolton
Analysis
The Anterior Bolton Index (ABI)
The ABI is obtained by adding the mesiodistal width of
the mandibular canines and incisors and dividing
this by the mesiodistal total of the maxillary canines
and incisors. The ideal ABI ratio is 77.2 +/- 1.65, which
provides for a cuspid Class I relationship.

Bolton Analysis
The Overall Bolton Index (OBI)
The OBI is obtained by adding the mesiodistal width of
the mandibular teeth from first molar to first molar,
and dividing this by the mesiodistal total size of the
maxillary first molar to first molar. The ideal OBI ratio is
91.3 +/- 1.91, which provides for a molar Class I
relationship.

Bolton
Analysis
Deviations from the ideal ABI or OBI ratio indicate a
tooth size discrepancy that may be treated using IPR
alone or in combination with other space-creating
methods.

Staging IPR
Staging IPR is important to consider when treatment planning,
starting with the tooth/teeth that require(s)
the most adjustment. If teeth are rotated or severely overlapped,
sequentially derotating them or removing
some overlap may make it possible to perform IPR on adjacent
surfaces to obtain the required space on the
true proximal surfaces (e.g., rather than removing enamel from a
buccal surface which is temporarily proximally
placed because of the rotation).

Staging IPR
Staged IPR should be treatment planned to:
• Improve access to proximal contacts
• Avoid IPR on inappropriate surfaces
• Perform IPR when suitable access to the mesial/distal surfaces is possible
• Avoid iatrogenic damage while performing IPR adjacentto severely
overlapped/rotated teeth
• Avoid creating excess space by removing too much in one phase
after IPR
before
IPR
before IPR after IPR

Staging
IPR
Excess space can result in aesthetic
problems and are as subject to food
impaction

The treatment plan must carefully consider which teeth
will receive IPR, and staging of IPR. ALL factors
discussed
above must be considered including: Inter-arch
relationship, tooth and arch width, crown-root width
ratio, bone crest and contact point positions, shape of
teeth, enamel thickness, tooth size discrepancy and the
presence of black triangles.

Assessing the Available Space & Space Required
for Tooth Movement
A space analysis should be performed using calipers on the patient’s
beginning stone model. The amount of
space (in millimeters) needed to resolve the crowding should be
determined and written in the treatment plan.
Depending upon the malposition of individual target tooth, the
measurements required for space analysis may
be taken from the buccal, lingual or incisal directions.

The space analysis begins by measuring the
width of each target tooth at its widest point.
These measurements
are then added together for the total width
(TW) of the target teeth.

The available space for each target tooth is then determined
by measuring the distance between each adjacent
tooth in relation to each target tooth. These measurements
are then added together for the actual space (AS)
of the target teeth.

The difference between the total width and the actual
space available represents the amount of space
required
(SR). Knowing how much enamel may be safely
removed from a tooth is crucial to the success of IPR.

The clinician may safely remove 0.5 mm of enamel from all
proximal surfaces except the incisors. For esthetics and
safety, enamel reduction of incisors should be limited to
0.25 mm at each proximal surface. This means that a total
of 3
mm of enamel can be removed from the mesial surface of
one cuspid to the mesial surface of the opposite cuspid.
(A) A right mandibular central incisor (arrow) showing a slight relapse
18 months after the end of treatment, (B) 3 years post-treatment: self-
correction after some stripping

If second molars are present, then 4 mm of enamel can be
removed from each side of an arch –( i.e., from the distal
surface
of the cuspid to the mesial surface of the second molar) –
for a maximum safe full arch space creation of 11 mm.

Obviously, less space can be obtained if there are missing
teeth and the extraction space has (partially) closed, or if
IPR
was performed during a prior course of treatment and
there is therefore less available enamel.

Measuring the Available Space: Alternative
Methods
Other methods for measuring the teeth and arch
width
include using a gauge in vivo. The teeth are
measured at
their widest point.
Measuring incisal width

The arch width can be measured canine-to-
canine where
only the social six are involved or second
molar-to-second
molar where the full arch is involved, using an
arch gauge
Measuring canine-to-
canine
Measuring second molar-to-second molar

Alternatively, floss or a ribbon can be used
to determine the
lengths and then measured against an
orthodontic ruler. Next,
the arch length difference (ALD) and space
requirements can
be assessed in the same manner as
before.

Procedural Considerations when Performing
IPR
IPR procedural considerations include the shape and
position of teeth being considered candidates for
IPR, treatment staging, the use of local anesthesia,
IPR method to be used, periodontal and caries status.

Dental and Soft Tissue Considerations
• Symmetrical midlines should be preserved
• Over-reduced laterals may resemble peg laterals
• IPR should result in a contact point aligned with the
vertex of the papilla
Asymmetrical midline Symmetrical midline

Dental and Soft Tissue Considerations
• Soft tissue must be protected during IPR
• Avoid creating wide interproximal spaces – these are a
risk factor for intrabony defects
• Enamel is generally thicker on the distal surface of the
tooth than on the mesial surface; this
needs to be considered with respect to the location of IPR

Manual vs. Mechanical IPR
• Manual IPR is less likely to result in soft tissue injury
• Manual IPR is more time-consuming than mechanical
IPR
• Mechanical devices require more intraoral space for
access
• The angle of approach during IPR is critical to the
contact points and tooth contours
• Unless performed along the long axis of the tooth,
IPR can result in poor contours and open contacts

Abrasive strips are usually used on anterior teeth. They
should be used carefully and care taken not to injure the
periodontal tissues or the lips and tongue. It has been
suggested by anecdotal evidence that the space created
by abrasive strips may actually be smaller than initially
observed due to compression of the periodontal tissues
when the strip is forced into an interproximal region.
MANUAL STRIPPING BY ABRASIVE METAL STRIP

These strips are available in different grades, and
progressively finer grit is used to obtain a highly polished
surface. IPR carried out in this manner is probably the
slowest of the methods used for IPR
MANUAL STRIPPING BY ABRASIVE METAL STRIP

Handpiece-mounted air-rotor burs are the
most commonly used and probably the most
effective way to carry out an IPR procedure.

The Ideal Interproximal Reduction System uses
handpiece-mounted metallic strips to reduce interproximal
enamel with a shuttle action, back-and-forth movement.
Additionally, flexible blades to contour and polish the IPR
surfaces are available

Manual vs. Mechanical IPR
• Contra-angle handpieces are suitable for the anterior
and posterior regions
• Straight handpieces with rotary discs are suitable only
for the anterior region due to limited space and access,
and a
disc guard should always be used to protect soft
tissues. Clear disc guards improve visibility vs. metal
guards

• Only strips are recommended to
break contacts with overlapping teeth
to avoid damage to enamel

Caries Susceptibility
There is no evidence that IPR is associated with an
increase in proximal caries lesions. Abraded enamel has
surface porosities and therefore remineralizes more
rapidly than nonabraded enamel, becoming more
resistant
to demineralization. Fluoride gel is recommended to
encourage remineralization

The Use of Elastomeric Separators
Elastomeric separators serve to:
• Create temporary space interproximally to enable
initial IPR
• Improve access where tight or overlapped contacts
are present
• Help avoid iatrogenic damage to dental hard tissue
and gingivae
These should be used prior to mechanical IPR (unless
space is already present for instrumentation), and may
also
be used prior to manual IPR.

Separators or elastomeric rings. They are
available as:
• Thin anterior separators
• Posterior separators
• Loose radiopaque separators

Separator pliers should be used when placing or
removing separators. These pliers have a notched tip that
helps prevent the separator from slipping during
manipulation, helping to avoid potential
ingestion/inhalation/
misplacement of separators. During removal, an explorer
may be used as an alternative.
Step 4: Measuring space createdSeparators 1 week
after placement
Step 1: Remove the
separators
Step 2: Measure the
space created by the
separators
Step 3: Begin IPR and
perform in stages

Alternative Method: Loop floss through the separator.
Then, while holding the floss at both ends, push the
separator into position and then remove the floss from
the separator.
Prior to IPR, separators should remain in place for:
• 2 to 4 days in the anterior region
• 1 week in the posterior region
The dental floss is used to 'slide' the separator between the teeth, the dental
floss is then removed

Prior to performing IPR, the separators are
removed and the space created by them is
measured. This is
critical as the space created is only temporary
and rebounds once the separators have been
removed. If
this space is not measured and considered, the
amount of space that must be created using IPR
based on
the treatment plan will be underestimated..

After the separators have been removed, the
procedure and
measurement during IPR are the same regardless of
which devices are used to perform IPR

Dental Interproximal Reduction (IPR) Gauge
Measure
Measuring the space created periodically
during IPR helps avoid creating too much
space.

NOTE: The Measured space will INCLUDE the space
created by the separators, which must be subtracted
out to
determine the space created by IPR.
Dental Interproximal Reduction
(IPR)Gauge

After sufficient space has been created, the proximal
contours are finished and polished.
Example pre-IPR
Following IPR on
bicuspid interproximal
surfaces
Perforated Diamond Finishing Strip

Topical Anesthesia
IPR elicits no dental discomfort, however separator
placement can cause discomfort and the gingivae may
be impinged upon during IPR. Topical anesthetic will
relieve IPR-related discomfort.
Options include:
• 2.5% Benzocaine gel
• Lidocaine gel
• Hurricaine gel
For patients who are extra sensitive, local anesthesia
may be indicated.

Manual Instrumentation
Options and Considerations
Options include perforated mesh strips that increase
visibility and help to remove debris during IPR.
Solid diamond strips can be used manually.
Using IPR files that do not have a cutting edge helps to
avoid the introduction of defects and poor contours
during IPR.
perforated mesh strips Solid diamond strips IPR

Serrated files (or saws) are used to break contact points
if theIPRfiles do not have a cutting
edge.
Then single sided or double-sided IPR files are used
(single-sided files enable IPR on one proximal surface at
a time).
Files that are color-coded based on thicknesses size
allow easy identification and process standardization
Serrated files
single
sided files
double-sided
files
color-coded files

Regardless of the method used to obtain space, gauges
are required for measuring the space created.
Performing IPR in gradual, sequential steps is essential
for good clinical outcomes.
Used during Interproximal Reduction
(IPR) to measure and confirm space.
•Markings at 3mm, 5mm and 7mm
along tip of instrument
•Doubles as periodontal pocket
measuring instrument
•Excellent for tucking ligature wires
•Autoclavable

Used during Interproximal Reduction (IPR) to measure and confirm space.
•Includes six gauges: 0.1mm, 0.2mm, 0.25mm, 0.3mm, 0.4mm, and 0.5mm
•Stainless steel
•Autoclavable

In a recent survey, we asked ClearCorrect providers to share their tips &
tricks for performing IPR. As you'll see, we got a wide variety of
responses, some of them contradictory. Everybody has their own
preferred techniques
Today, we're passing on some of the responses we got. Nothing here
should be taken as official advice or recommendations from
ClearCorrect or its employees—use your professional judgement to
evaluate what's best for you and your patients
Tools for performing IPR
Based on our responses, the most popular tools for performing IPR are
diamond strips, followed by burs and diamond discs

Doctors who prefer strips said:
•“Floss first then diamond strip.”
•“I usually underprepare the IPR so that the reduction
gauge is difficult to fit between the teeth. If needed, more
can be done later, often with a finishing strip, so that a
closed contact can be reliably achieved.
“I generally do IPR with manual strips every six weeks until
contacts are not tight. I don't think this is better I am just
more comfortable with this.”

Doctors who prefer strips said:
* Pre-wedging prior to IPR and starting with strips prior to
discs.”
“IPR first with hand strips. Also, I find it easier to IPR when
teeth are aligned first in the contact areas.”
* Start with the thin stainless steel strips and switch to the
thicker carborandum strips as contacts become less tight.
* “I like to use a long finishing diamond to do IPR because
I think it gives me more ability to maintain ideal proximal
tooth contours

Doctors who prefer burs said
“I find it’s easier to do IPR with burs as opposed to discs and strips. The
smallest bur that I have found for 0.3mm is the mosquito interproximal from
Neo Diamond. #1416f
•“I prefer a mosquito diamond to discs for IPR. I feel like I can shape it better.”
•“I use ContacEZ high speed mosquito bur 1.6mm x 5mm length

•“Mosquito burs are much easier to use and safer than discs, especially
posteriorly.”
•“I use a Brasseler mosquito bur from the cervical incisal to prevent lodging
and make sure contact is completely broken

•“I have stopped using the discs and use the mosquito bur to open
the contact at the correct angle then I also use it to provide the
correct proximal contours. Then I use the strips to finish to final IPR
spacing and polish.”
•“A high speed air turbine and bur seems to be the quickest and
most controlled method.”
Safe-Tipped Diamond Bur

Doctors who prefer discs said:
“Start with low speed and stay in clear vision and control of the procedure. I
use loupes 3x or microscope to do it.
“It’s important to reduce straight (not angulated) and to carry the separation
through the contact areas.
“I use a slow speed straight hand piece with a VisionFlex disc. Fast and
smooth and has many uses. You must be very careful.
•“Have different sized discs.”
•“Just remember to use a guard on the wheel.”
•“Use reciprocating files when extremely crowded and then rotary
diamonds.”
•“Use Brasseler perforated diamond disc - tissue guarded mandrel is an
absolute must use.

And some doctors prefer other tools
•“Always use diamond floss.”
•“Use a combination of diamond discs on the slow speed hand piece
with a soft tissue guard. Measure the amount of reduction done. Finish
the IPR with hand strips. Check with an explorer to make sure that there
is not a ledge left. Before starting any case involving IPR, inform the
patient that it is needed
“I use a Komet, USA IPR kit with a reciprocating hand piece and safe
tips. Then I finish with diamond strips to smooth and finish and
contour. The gauges to confirm amount removed are integral as well.

•“I routinely perform IPR with a high speed hand piece and tapered
carbide bur in conjunction with fixed appliance treatment. IPR occurs
after separation of the contact points, and is performed on molars,
bicuspids, and cupids as needed.”
“Use a high speed with a needle fine diamond. Check with the spacer key.
Then round off the edges with the Diamond to restore anatomy. Done.”

•“Get the electric wiggle saw. I do not know the name. Safe and effective.”
•“On an extremely tight contact, I will place a separator for a few minutes prior to
IPR. When I remove it and perform IPR, the patient is more comfortable and the
strips do not break as often.”
•“I use an oscillating hand piece made by Komet. It's easy to use and relatively
comfortable for patients

General thoughts on IPR
Some doctors prefer to perform IPR after aligning teeth, some from
posterior to anterior and some prefer to perform IPR after arch expansion to
allow access. Here are a few general tips from providers:
•“Measure, re-measure, recheck before IPR, and also during the process.”
•“Under IPR rather than over IPR.

•“The trick is to have the ClearCorrect technicians expand the arches
to create more access to the area that is supposed to get IPR. I do use
a mosquito nose diamond burs from SS White. It’s called a piranha
diamond burs very fine, .”
•“Do the posterior first, then anterior later.”
•“Use a steady hand to be sure you don't open up too much space. I've
used local anesthesia before on very sensitive patients.
Mosquito Nose Piranha Diamond Burs

•“Always use a gel topical anesthesia on the soft tissue, acts as a lubricant as
well as anesthetic. And separate the teeth with a soft flexible wedge. It eases
access and protects the soft tissue.”
•“I like to use topical fluoride after IPR, trying to remineralize the cut enamel.”

interproximal reduction of enamel as part of orthodontics

interproximal reduction of enamel as part of orthodontics

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to interproximal reduction of enamel as part of orthodontics

Similar to interproximal reduction of enamel as part of orthodontics (20)

More from Maher Fouda

More from Maher Fouda (20)

Recently uploaded

Recently uploaded (20)

interproximal reduction of enamel as part of orthodontics