Implants in orthodontics a paradigm shift /certified fixed orthodontic courses by Indian dental academy

Implants in
Orthodontics
A Paradigm shift
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Introduction
a) Anchorage control during orthodontic treatment is essential for
obtaining non compromised results.

b) Conservation of anchorage in totality has been a perennial problem to
the traditional orthodontist.


Classification of Anchorage
Anchorage has been classified as
* Group A+ :- distalization of upper molar is
to be performed when more space is
required for retraction of the anterior
segment, than what is obtained by
extraction of Bicuspids.

* Group A :- more than 75% of the extraction space is
required for retracting the anterior segment.

* Group B :- describes symmetrical space closure with equal
movement of the anterior & posterior teeth to close the
space.
* Group C :- this is a category of non- critical anchorage
wherein 75% of the space closure is achieved by mesial
movement of the posterior teeth.

Methods of Anchorage control
Conventional

Extra oral

Intra oral

Head Gear

Dental anchors


The Paradigm Shift is the usage of
implant as skeletal anchors to overcome the
problems of conventional anchors.


Problem with Conventional
anchors
* Head gears require patient compliance so
as to be an effective source of anchorage. If
the patient is not co-operative enough with
the treatment, anchorage preservation
becomes a difficult issue to tackle.
&
* There are also many reported cases of Head
gear injuries.

While problems with dental anchors are
that, the anchor units experience a reciprocal
effect of the forces applied to move the
remaining teeth to their optimal positions –
thereby tending to move towards the
direction of the force applied.

Therefore skeletal anchorage through
implants is chosen to limit the extent of
detrimental, unwanted tooth movement.

Implants
* Definition:- according to Boucher – implants
Definition
were defined as alloplastic devices which were
surgically inserted either into / onto the jaw
bone.


Historical Background
* Gold & Ivory implants were used in the 16th
century in Chinese civilization for
replacement of missing teeth.
* Metallic implants were developed only in
the early 20th century.
a) The initial implants – were made of
precious metals like gold & iridium.

b) Cobalt – chromium & Titanium implants
were introduced in the 1940’s & 1950’s.
c)Non- metallic implants like vitreous carbon
& bioglass were introduced in the 1970’s.
It was found out that Vitreous carbon
implants showed a failure rate of 67%
during orthodontic loading.

Early studies on
Implants

• Gainsforth & Highley in 1945 used
vitallium screws in 6 dogs. The implants
were inserted in the ramal area, immediately
loaded & used for retraction of the upper
cuspids. They observed that all the screws
were lost within a period of 16 to 31 days.

* Linkow in 1970 used an implant for
replacing a missing molar tooth. This
implant was then used as an anchor source
to which class II elastics were attached for
retraction of upper anteriors.
The major disadvantage with this study was
that long term stability of the implant was
not reported.

CREEKMORE(1983) reported the possibility of skeletal anchorage in
orthodontics .
ROBERTS(1989) used conventional two stage implant in the retromolar
region to help reinforce anchorage for successfully closing the first
molar extraction site in the mandible . After completion of the
orthodontic treatment the implant was removed and histologically
analysed . They found a high level of osseo integration had been
maintained despite the orthodontic loading.
HIGUCHI and JAMES ( 1991) used titanium fixtures for intraoral
anchorage to facilitate orthodontics tooth movement.


Structure of an Implant
Implant
Body

Head
(Serves as)
Abutment in prosthetic
rehabilitation

Attachment source for
elastics & coil springs in
orthodontic treatment


The portion that is embedded in the bone is
termed as Body.
The Body is divided into 2 types
a) Screw type
b) Plate type


Classification of Implants
I) Based on location :- they are classified into,
a) Sub-Periosteal:- here the implant body lies over
the bony ridge.
Eg:- Onplant
The disadvantages of the onplant system are
that – the chances of dislodgement are high,
their complexity of the design & the cost
factor (as these are very expensive).

b) Transosseous:- Implant body penetrates
into the bone. The disadvantages of this
system were – they might damage the
intrabony structures like the nerves & blood
vessels.


c) Endosseous:- here the Implant body is partially
submerged & anchored within the bone.
These type of Implants are the ones which are
widely used now.


II) Based on Implant Morphology:
Implants

Screw type

Blade/ Plate
Disc type


type

III) Based on composition:
a) Stainless steel
b) Titanium
c) Cobalt- Chromium- Molybdenum
d) Ceramic
e) Miscellaneous:1) Vitreous carbon
2) Composites
3) Poly lactic acid resorbable

IV) According to the surface structure:- implants
are classified as
a) Threaded & Non-Threaded – the Threaded
implant provides greater surface area & thereby
increases the stability.
b) Porous & Non-porous – in the case of Porous
implants – the vents in the implant body aids in
the ingrowth of bone resulting in a better
interlocking between the implant & the bone.

V) Based on integrity to the bone:a) Osseointegrating – the term osseointegration
implies an intimate structural contact between
the implant surface & the adjacent vital bone,
devoid of any intervening fibrous tissue.
Eg: Onplants, Orthosystem
The advantages of osseointegration are that
there is an excellent adaptation of the implant
to the bone surface thereby ensuring better
stability.

The disadvantages of osseointegration are:1) Two surgical procedures are required – one for
placement of the implant & another for removal
of the implant.
2) Immediate loading is not possible as adequate
time is required for osseointegration.


b) Partially osseo-integrating / Non-osseointegrating:Non-osseointegrating
The stability of the implant is by mechanical
retention aided by the threads present in the
body of the screw.
Eg:- Miniscrews.
The advantage of this type is that, since they do
not osseointegrate – they can be easily placed in
the required area with minimum surgical
procedure & also removed with ease by just unscrewing
them with the same drivers used for inserting them.

Bone Tissue
Three distinct types of bone (woven, lamellar, and composite) are involved in
postoperative healing and maturation of the osseous tissue supporting an
implant . Woven bone has high cellularity, a rapid formation rate (30 m/day or
more), relatively low mineral density, high random fiber orientation an poor
strength. It serves an important stabilization role in postoperative healing of
endosseous implants . During the initial healing process woven bone fills all
spaces at the bone-implant interface. Although capable of stabilizing an
unloaded implant, woven bone lacks the strength to resist masticatory function.
Lamellar bone is the principal load-bearing tissue of the adult skeleton. It is the
predominant component of a mature bone-implant interface. Lamellar bone is
formed relatively slowly (less than 1.0 m/day),has a highly organized matrix,
and is densely mineralized.
Composite bone is a combination of paravascular lamellar bone deposited on a
woven bone matrix.. Formation of composite bone is an important step in
achieving stabilization

Finite Element Analysis of Endosseous Implant and bone after
vertical,horizontal and diagonal loading by Kobel and Harzer.
Three types of endosseous implants (all 9 mm in length and 3.3 mm in diameter,
made of titanium) were used for this investigation. Type 1 was a simple,
cylinder-shaped implant; type 2 a cylinder-shaped implant with a
superperiosteal step; and type 3 a cylinder-shaped implant, subperiosteally
threaded, with a superperiosteal step. The load on the implant was
investigated under three conditions of bite and orthodontic forces from 0.01
to 100 N (vertically, horizontally, and diagonally).
Vertical loading caused deformation of trabecular bone with all three implant
geometries .Trabecular bone deformation was reduced by a superperiosteal
step in the design. Horizontal loading of the implants shifted the deformation
from the trabecular to the cortical bone. large deformation was measured at
the transition from cortical to trabecular bone. The smallest deformations
were found for implants with a superperiosteal step and diagonal loading .
The use of threads provided no improvement in loading capacity.

The predictable use of implants as a source of orthodontic and dentofacial
orthopedic anchorage requires a practical understanding of the fundamental
principles of bone physiology and biomechanics.

Optimal use of osseointegrated implants requires a thorough knowledge of bone
biomechanics, particularly when the patient is skeletally and/or periodontally
compromised
An evaluation of bone metabolism is a key element of the diagnostic workup. The
minimal screening procedure involves a careful medical history, evaluation of
signs and symptoms of skeletal disease and an assessment of risk factors
associated with negative calcium balance.


The most prevalent metabolic bone diseases in middle-aged and older patients are:
a) Renal osteodystrophy-poor bone quality (fibrousdysplasia) that is secondary to
inadequate kidney function .
b) Hyperparathyroidism-elevated serum calcium is often associated with highturnover osteopenia (low bone mass) secondary to a parathyroid
adenoma .
c) Thyrotoxicosis-high bone turnover leading to osteopenia, associated with
hyperthyroidism orovertreatment of hypothyroidism .
d) Osteomalacia-poor mineralization of osteoid is due to a deficiency of the active
metabolite of vitamin D (1, 25-dihydroxycholecalciferol) .
e) Osteoporosis-usually defined as symptomatic osteopenia; most common fractures
are of the spine, wrist, and/or hip. Fragility of other weight bearing joints such
as the knee and ankle are also common problems.


Anchorage derived from implants:implants
a) Direct:- an endosseous implant is used as an anchorage
Direct
site.
b) Indirect:- there are 2 types
Indirect
1) Orthopedic :- for maxillary expansion & maxillary
protraction.
2) Dental

Dental anchorage

For
space
closure

For
distalization
of teeth

For intrusion

anteriors

posteriors


Implants for Maxillary Protraction
a) Shapiro & Kokich 1984 used ankylosed teeth as

anchorage for skeletal protraction wherein
deciduous canines were intentionally ankylosed
& protraction head gear was given.
The intentionally ankylosed teeth were used as
osseous handles & were called as
Pseudoimplants.

b)Smalley et al 1988 used Branemark implants into the maxilla, Zygoma,
Orbital & Occipital bones of monkeys. A force of 600 gm was delivered to
maxillary and zygomatic bones . A 12mm widening at the
zygomaticomaxillary suture was seen and 16mm widening at
zygomaticotemporal suture was observed.
The dental changes seen were a 5-7mm change in overjet.
They observed that skeletal protraction occurred along with dental tipping.


Implants for maxillary expansion
a)

Movassaghi et al 1995, tested frontonasal suture
expansion in rabbits from an implanted titanium screw
device with plates. After 4 weeks of healing , 55gm of
force was applied for a period of 5weeks.
On observation it was found that there was significant
increase in the growth across the frontonasal suture.


b) Andrew parr et al 1997 conducted experiments on mid-nasal expansion
with endosseous titanium implants.

The sample groups were divided into one control & two experimental
groups. For the two experimental groups loading forces of 1 N & 3 N
were applied.

92 % implant stability was observed .
Sutural expansion of 5.2mm and 6.8 mm respectively was seen in the
1N and 3N load categories. Mineral apposition and bone formation
rates were significantly higher in the experimental group. The 3N group
showed more expansion but this did not affect the rate of bone
formation across the suture

Implants for Dental anchorage – earlier
studies
a) Implants for intrusion of teeth
Creekmore in 1983 published a case report of usage of a vitallium implant for
anchorage, while intruding the upper anterior teeth. The vitallium srew was
inserted just below the anterior nasal spine . After an unloading period of 10
days, an elastic thread was tied from head of the screw to the arch wire.
Within one year, 6mm intrusion was demonstrated along with 25 lingual
torque .


b) Another study by Southard in 1995 compared the intrusion 'potential of
implants with that of teeth (denta1 anchors). Titanium implants were placed in
extracted 4th premolar area in dogs, followed by an unloading period of three
months. Then, an intrusive force of 50-60 gm via 'V' bend was effected. This
was compared with intrusive potential of teeth on the other side using the
same mechanics. No movement of implant was seen at the end of the
experiment whereas, on the other side, the tooth acting as the anchor units
tipped severely. Therefore, implants are definitely superior to the teeth acting
as anchor units.


Classification of Implants for Dental
anchorage
Based on the area of placement :a) Sub- periosteal
b) Osseous
c) Interdental

Based on Implant Morphology:

a) Disc type - Onplant
b)
1)
2)
3)
4)
5)

Screw type –
Mini – implant
Orthosystem
Aarhus implant
Micro implant
Spider screw, Omas screw

c) Plate type –
1) Skeletal anchorage system
2) Graz implant supported system
3) Zygoma anchorage system

Sub Periosteal implant
The disc type implant is used.

Block & Hoffman in 1995 developed this system
which consisted of Titanium circular disc of 8 – 10mm
in diameter & 3mm of average thickness.

Osseointegration :- The undersurface of the disc is
coated with Hydroxyapatite which is a bioactive
substance aiding in osseointegration & thereby
improving the stability of the implant.


Criteria for usage:- Onplant can be used only in
skeletally mature patients.
Pre-Surgical procedure:- An impression is made
of the maxillary arch . A clear vacuum formed
stent covering the palate is fabricated – with a
small piece of clay placed for relief on the region
where the Onplant is to be seated.
The use of the stent is
a) To place a small amount of pressure on the
palate after onplant placement so as to avoid
migration of the onplant & to prevent hematoma
formation.
b) It aids in better patient comfort.

Onplant installation
Involves two stage surgical procedure.
Stage I:- the steps are
1) Disinfecting the working area (intra oral) with 0.5%
chlorhexidine mouthwash.
2) Administration of local anesthesia to the palatal soft tissue –
from the canine area to the midline palatal tissue opposite
the 1st molars.
3) Following adequate anesthesia, a 15-25mm long incision is
made in the palate adjacent to the canine & premolars
within 5mm of these teeth.

Advantage of this incision is that – it maintains intact tissue at & near the
final position of the onplant thereby minimizing the risk of soft tissue
breakdown during the healing period.
*** the incision is placed far from the midline of the palate.


4) Periosteal elevator is used to conservatively open a subperiosteal tunnel which extends across the palatal midline
opposite to the 1 st molar.

Requirements of the tunnel:- a) It should be of a limited width
to avoid onplant movement when once placed firmly.
b) It should be sub-periosteal so that the onplant can directly
contact the bone.

Steps cont’d:
5) Bone file may be used to level any bony irregularities so
as to create a flat seating area.
6) Onplant is picked with its inserter & carried into the
tunnel opening.
7) Periosteal elevator is used to ensure direct vision for
onplant placement.
8) Onplant is slid through the tunnel to its final resting
position on the hard palate.


9) The inserter is released from the onplant ( after
pressing the onplant towards the bone with one
finger through the overlaying soft tissue) & pulled
out of the tunnel.
10) The incision is then sutured.
11) Small amount of tissue conditioner is placed in
the relieved area of the vacuum formed stent & the
stent is seated completely.

12) Patient is placed on antibiotics & analgesics.
13) After 7 days post surgery – the sutures are
removed.

Precautions to be taken during the 1st stage of surgery
a)
b)
c)

d)

Onplant should not be placed on the periosteum/ gingival
tissue as it will not osseointegrate.
The Hydroxyapatite surface should not be touched with talc
covered gloves as it will also interfere with the osseointegrate.
Onplant should be placed on a stable/ flat bone surface so that
it does not wiggle under palatal soft tissue.

Stent should not be removed for the 1st 24 hrs. patient is
advised to remove it only for cleaning.

e) If bleeding / swelling / pain occurs, patient should be asked to visit
the surgeon.
f) Onplant should not be exposed( for abutment placement) till 16
weeks. This is the time required for osseointegration between the
onplant & the bone.
* * * IInd stage surgery:- for abutment placement.
Procedure:
1) Onplant is located by palpating the elevated site on the palate.
2) Local anesthesia is injected to the surgical site.
3) Small incision is made to confirm the specific location of the
cover screw.
4) Cover screw is exposed by tissue punch & removed with a
hexagonal screw driver.

5) Connective tissue remnants (covering the onplant) are removed with a

surgical blade.
6) Abutment is placed & T
rans palatal arch is fabricated.

Uses of Onplants:•
•
•

For Enmasse retraction of the anteriors.
For distalisation of posterior teeth.
For intrusion of posterior teeth especially the maxillary
molars.

Disadvantages of Onplants:Onplant placement
• Long waiting period for healing/ osseointegration prior to
orthodontic loading.
Abutment placement
• Surgical procedure involved is three Onplant removal

Osseous Implants
Definition:-

Implants placed in dense bone like Zygoma, Body &
Ramus of the Mandible, Mid-palatal areas.

Eg:-

1) Skeletal anchorage system:-

Umemori et al 1999, developed this
system which consists of miniplates stabilized with screws. These were placed
in Maxilla or Mandible.
They differ from the surgical miniplates, wherein they have been modified for
attaching elastomers/ coil springs.
There are 2 types of plates classified based on shape into,

a)

L shaped


b) T shaped – which is used for intruding anterior teeth.

The diameter of the screw used for fixation of 2 to 2.5mm.
Procedure for placement:- 1) Incision is made.
2) Flap to be raised at the site.
3) Prior to incision, the implant site is assessed radiographically for any erupting
tooth, evaluating the sinus & its lining & inferior alveolar canal.
4) Miniplate is adapted to the contours of the bone.
5) The end of the loop of the miniplate is bent outward to remain exposed into the
oral cavity.

Uses of the Loop:- it acts as the site of attachment for orthodontic
force application.
Following placement, 3-4 weeks of healing period is allowed prior to
force application. In cases of molar intrusion, buccal root torque
value is to be increased to prevent excessive buccal flaring of the
teeth.
2) Zygoma Anchorage system:- developed by Hugo de Clerck et al 2002.
system
This system consists of curved titanium miniplate with provision for using 3 screws of 2.3mm
diameter each for improved stability.
Area for placement:- this system is designed for use in the Zygomaticomaxillary buttress
area between 1st & 2nd molars.


The author states that the disadvantage of the conventional miniscrews is their proximity to
the roots, as a result the screws may damage the roots during placement, whereas the
miniscrews in this system are placed at a safe distance from the roots of the maxillary
molars.
The combination of 3 screws along with the miniplate is to bring the point of force
application near the center of resistance of the 1st permanent molar.

3) Graz implant supported system :- introduced by Karcher, Byloff et al
in 2000.

This system consists of modified Titanium miniplate with 2 oval shaped cylinders
attached to it & provision for 4 miniscrews. It was mainly used as a support
( like a nance button) in a pendulum appliance.


Orthosystem Implant
Developed by Wehrbein et al . this is a titanium screw implant of length 4 or 6mm
and diameter of 3.3mm. It can be inserted in the mid-palatal area of the maxilla
& in the retromolar area of the mandible.
These implants are surface treated with sand blasting & acid etched to improve
integration to the bone. Osseous implants produce effective anchorage during
tooth movements but require complex surgical procedure for placement & for
removal of the implant & also the chances of infection arising around the periimplant area is more.


Screw type Implants
Areas of placement

Anterior nasal
Spine

Interdentally

Buccal

Midline of the palate

Retromolar
area

Palatal

Advantages:1) They are of smaller diameter.
2) They attain stability basically by Mechanical retention & partly by osseointegration.
3) Placement is very simple.
4) Implant removal is also very simple as they are only partially osseointegrating in
nature.

Types of implants
1) Mini Implants developed by Kanomi et al 1997
2) Aarhus implants developed by Melsen B et al
3) Micro-implant anchorage developed by Kyung et al
4) Omas bone screw developed by Lin et al
5) Miscellaneous

Implants used in the mid-palatal area
I)

Anatomical Basis:
a) Karl Andreas Schlegel et al 2002 conducted a study
on a population with age ranging from 12 to 53 years.
They observed that

1) Maxillary bone was classified as grade 3 due to a thin
corticalis & only relative dense trabecular structures.
2)The bone thickness in the midline of the palate was around
1.5cm
3)A gap of 0.03cm between the osseous wings was more evident
in the anterior region of the Suture Palatina Media (SPM) than
in the posterior region.


They concluded that
1) The Posterior region of the SPM offers better site for
placement of osseointegrating implant as the gap between
the osseous wings is low when compared to the anterior
region.
2) Even though the gap in the anterior region is 0.03cm
between the osseous wings, an implant of 0.4cm could be
placed as they have the ability to osseointegrate.
3) The implants to be placed in the mid-palatal region- the
ideal age according to them is above 20 years.

Radiological assessment of Palatal bone
thickness

I) Wherbein et al 1999 evaluated bone height in the mid-sagittal
region & also compared the cephalometric assessment with clinical results
obtained during the insertion of the implants.

Procedure:1) The Implant size was assessed by measuring the vertical bone height on the lateral
cephalogram.
2) The surgical procedure was performed by removing the palatal mucosa with a
standard punch & then the bone was drilled with a pilot & profile drill.
3) Probing was performed with sterilized periodontal probe( Brod 25G, Ash,
Weybridge UK) which was set to indicate a force of 0.2N to detect any bony
perforation to the nasal sinus.
When the cavity revealed a resistance of 0.2N – it was diagnosed as no perforation to
the nasal cavity.
1) Implant was inserted.
2) Following this another radiograph was made with the implant in position.

Parameters used for radiologic assessment were,
a)
b)
c)

Implant position with respect to the section of the palate.
Implant angulation to the palatal plane.
Distance between
MCBI- Most cranial border of the implant
&
MCBPC- Most cranial border of palatal complex


.

Conclusions of the study were:1) Mid- sagittal area of the palate is a valuable insertion site for implants.
2) Sufficient bone support is available in the anterior & middle sections of the midpalate for implants of 4mm & 6mm length & 3.3mm diameter.
3) Vertical bone support in the mid-sagittal area of the palate is atleast 2mm more
than what is predicted in the radiograph.
4) Implant angulation has a considerable influence on remaining vertical bone height
above the MCBI. If the angle between the implant axis to the ANS-PNS is small- it
indicates more residual bone is available above the MCBI.
II) Henriksen et al 2003 conducted a study to evaluate bone thickness in the anterior hard
palate inferior to the incisive canal.
Procedure:- 25 dry skulls were assessed radiographically( lateral ceph) & vertical
thickness of the mid-palate was measured.
Gutta Percha was injected into the incisive canal & radiograph was repeated. Bone
thickness was measured from inferior hard palate to inferior most part of the canal.

Observation :-

Only 4.3+/- 1.6mm of bone is available for the implant. Therefore
they concluded that implants of 4mm in length could be used freely (without any
anatomical limitations) whereas that of 6mm should be used with caution.

3) Gahleitner et al in European journal of radiology
2004 , performed a study wherein Dental C.T was used as a tool to locate the
optimal size & position for orthodontic implant placement.

Procedure:-

1) Axial C.T scans of the maxillary bone were acquired.
2) Paracoronal views were reconstructed & measurements of the palatal bone height
in 3mm increments from the incisive canal were performed.

Results:-

a) Overall mean bone height was 5.01mm with standard deviation of 2.60.
b) Maximum palatal bone height was 6.17 with SD 2.81 at 6mm dorsally from the incisive
canal.


Presurgical preparation:1) Laboratory test to be performed include evaluation of Bleeding time &
Clotting time and Blood pressure evaluation.
2) One hour prior to surgery – Antibiotic prophylaxis ( preferably 3gm of
Amoxycillin) is given. If the patient is allergic to Penicillin – Cephalexin/
Erythromycin can be given.
3) Intra-oral disinfection is done with 0.2% Chlorhexidine gluconate
mouthwash.
Area for placement of the implant:-

Jessie Jacob et al preferred placing the implant in the palatal
midline between 1st premolars. They also stated that implant
placement should take into consideration – that a bone bed
more favorable for osseointegration might be found
posterior to the interconnecting line of the 1st premolars.


Types of Mid-palatal Implants

Orthosystem

Micro-Implant


Stent preparation :Tinsley et al JOO 2004

have advocated preparation of a stent
prior to the surgical procedure of Implant placement.
The stent is of 2 types

Radiographic

Surgical


The radiographic stent consists of 2 metal tubes of the same
diameter & length as that of the implant. The tubes are
positioned with an acrylic base plate. Advantages of using
the tubes of same size as that of implants is to account for
any x-ray magnification.
The metal markers are placed in the region between premolars
& angled approximately perpendicular to the curve of the
plate. The stent is then fitted into the patient’s mouth &
radiograph is taken. This radiograph allows accurate
assessment of the bone depth & shows the position of the
nasal floor.


The radiographic stent is now converted to a surgical stent by removing the markers &
preparing a 6mm hole in the acrylic base plate so that it acts as a guide through which
the implant preparation drills can be used.

Surgical Procedure: A) for orthosystem implant:
The implant is available in 3.3 mm diameter, self tapping and in 4/6mm length.
The surface is sand blasted & acid etched to maximize the stability – wherein high level of
direct bone contact occurs during osseointegration.
Steps: 1) Palatal mucosa is firmly anesthetized.
2) Mucosal trephine is used with a slow speed hand piece to remove the mucosal tag.

Mucosal trephine bur

3) A round steel rose head bur is used to gain access to the softer cancellous bone of the
palate. The hand piece is run at not more than 700 rpm. Copious saline irrigation is
performed during the drilling procedure so as to ensure that bone does not get heated
thereby preventing a) Tissue & osseous necrosis & b) Implant failure.
4) A profile drill is used to prepare the site. The cutting part is available in 2 lengths of 4 &
6mm. The length of the shank is also variable depending on the shape of the palate.
Longer shank allows easier access in high vaulted palate cases.
5) The drill should move into & out of the bone only once & in 1 direction. The preparation
should be parallel sided to achieve primary stability.
6) Once the site is prepared, its checked with a periodontal probe to ensure adequate depth
is present & that no perforation into the incisive canal has occurred.


7) Implants are picked from sterile ampoules in which they are
stored. They should not be touched with gloved hand as they may
get contaminated.
8) Implants are placed with finger held instrument called “ Ortho
Inserting device” & then tightened with a ratchet until they are
seated firmly.
9) Once inserted, they are assessed for stability. If they are found to be
stable, a healing cap is placed over the implant & a radiograph is
taken to assess/ confirm its position.
Implant in position


10) Implants are left unloaded for 3 months, the implant is reviewed clinically
to check for stability.
If they are found to be stable – a Trans Palatal arch is fabricated.
(types)
Banded

Bonded


The disadvantage with the bonded TPA was that the Debonding rate was
found to be extremely high because – during mastication the anchor teeth
moved within the Periodontal ligament whereas the implants were rigidly
fixed to the bone as a result – a differential movement occurred which
caused the bond failure to occur between the TPA & the tooth.
Tinsley et al 2004 have advocated the use of a lingual hinge bracket- which
can be welded to the bands of the anchor teeth. The size of the bracket
slot limits the dimension of the TPA to 0.8mm.
The advantage with the hinge bracket is that- path of insertion problems as
with conventional attachment of the TPA to the bands can be eradicated.
Here the bands are cemented prior to TPA placement, the TPA can be
placed & the hinge clip can be closed over the TPA.


Procedure for Micro-Implant
placement:
1) The drill should be checked before surgery for any bends so as to prevent any
wobbling & enlargement of the site of implant placement.
2) A low speed contra angle hand piece with a drill size 0.2 to 0.3mm narrower than
the microscrew used for initial entry into the bone.
The micro-implant itself should not be used for self drilling as this may lead to
metal fatigue & eventually fracture of the screw.
3) The drill can penetrate the mucosa & underlying bone without a surgical flap. The
drill speed should be 400-500 rpm & it should be used along with copious
saline irrigation to keep the surgical site lubricated.
4) When drilling into the dense bone – careful up & down strokes should be done to
minimize the heat generated by the slow speed handpiece.

Micro-Implant Driving Methods

2. Self–drilling procedure
Two-step

One-step

or
After indentation

(suitable for Diagonal insertion

1) Driving

Without indentation
(suitable for Perpendicular insertion

& thick cortical bone)

& thin cortical bone)

Dia.; less than 1.5mm

Dia.; more than 1.5mm
for Ortho. Micro- &MiniImplant

Micro-Implant Driving Methods

3. Self –tapping procedure

1) Indentation
One step

Two step

o
r (in case of very thick cortical bone)
2) Drilling
o
r
3) Driving

for Ortho.Micro-Implant:
Dia.; less www.indiandentalacademy.com
than 1.3mm

Insertion of the micro implant
The implant can be inserted into the bone either with Hand driver / with an
engine driven screw driver.

Manual screw driver is of 2 types

Long

Short

designed to be used in
the buccal surface

designed to be used
in the palatal area


Engine driven screw driver in a low speed contra angled hand piece can
also be used for placing the micro-implant. Manual screw driver is
always preferred over the engine driven for safety reasons.

** Important considerations during the implant placement:
a) if resistance is encountered, the implant should be withdrawn & the
bone to be redrilled with pilot drill before implant reinsertion.

b) if the implant fit is not tight, a new site adjacent to the original one may
have to be prepared/ the implant may have to be replaced with a larger
one.


Following insertion, the fit of the implant is assessed
clinically.
A Trans Palatal arch is then constructed.

If the implant is to be used for effecting tooth movement
– immediate loading of force can be performed with
Nickel Titanium coil springs.


Post surgical instructions
1) 0.2% Chlorhexidine mouth wash to be used daily.

2)      Patients shoud be instructed to clean the implants
initially with cotton wool bud & then with small headed
tooth brush as soon as the mucosal tenderness wards
off.

3)      Patients should be instructed not to play with / push
the implant with the tongue.

4)      Analgesics & antibiotics are prescribed with specific
instructions on their use if required.

Applications of Mid-palatal implants:
1) To serve as anchorage during space closure, wherein the anchor teeth
can be attached to the implant thereby preventing their migration
during force application when Enmasse retraction is carried out.
2)
For intrusion of the Molars

Unilateral

Bilateral

3) For Distalization of molars- in groupA+ anchorage cases.

** Histological evaluation
In the case of Osseointegrating implants – histological evaluation
revealed a high percentage of predominantly mature lamellar bone
in direct contact with the implants which added stability to the
implants.


For the non-osseointegrating implants – the thin, keratinised
soft tissue is more advantageous.
Yun et al 2001 state that adequate screw stability in the
palatal slopes is difficult to obtain because the mucosal
thickness is 2 to 3 times more.
They have also reported that soft tissue thickness of 1mm is
present in the mid-palatal area 4mm posterior to the incisive
papilla & thereby have concluded that soft tissue in the midpalatal area is optimal for miniscrew implantation.
In terms of Hard tissue- the implant (non- osseointegrating)
stability depends on quality & quantity of cortical bone.

Park et al state that mid-palate area is composed of a good of cortical bone
corresponding to D1/ D2 of Dr.Misch classfication of the maxillary
bone. They also state that the screw stability can be enhanced by
splinting 2 miniscrews together.

** Implant Removal:1) For Osseointegrating implants:
1)
2)

3)

Involves a second surgical procedure for implant removal.
Standardized Trephine which is precision guided through the
implant neck & through a cylindrical sleeve (4.2mm) is screwed
into the abutment.
Procedure to be performed under local anesthesia.

2) For Non-osseointegrating implants.
a)

No such second surgical procedure required.

b)

As total osseointegrating does not occur, the screw driver is engaged
in the screw head & is turned in the direction Opposite to that of
insertion.

c)

L.A is not required for removal.


Advantages of P
alatal Im
plants
According to Jessie Jacob et al, the palatal implants,
1) Preserve anchorage well.
2)

Have better tolerance from the patient when compared to extra- oral
devices used in anchorage preservation.

3)

There is no risk of Bony defects around the implants as the palate is a
quasi –flat surface.

4)

As the palatal mucosa is highly keratinised, peri-implant soft tissue
conditions are favorable creating a firm connective tissue sealing.

5)

The implants can’t be disturbed by chewing forces.

LONG TERM STABILITY OF
IMPLANT

Miyawaki et.al analysed the success rate of three different screw
sizes and a miniplate design.
Their sample consisted of 51 patients who had 134 different implants
used for conserving anchorage.
The implants were in the form of screws(134 in number) of 1.0, 1.5
and 2.3 mm diameter as well as 17 miniplates.
On one year after placement, they drew the following conclusions:
a) The implant screws of 1 mm diameter had a high failure rate and
are not recommended for clinical use as Orthodontic anchors.

b) Implant screws of 1.5 and 2.3 mm diameter had
reasonable success rates - 84 and 86 % respectively and
therefore could be used in majority of the cases.
c) The miniplates had the best stability (96%), but the
surgical intervention and patient discomfort was greater
with these compared to miniscrews. Miniplates have
beenrecommended in high angle patients.
d) Peri-implant hygiene is one of the major factors, which
could affect the stability of these implants.


FUTURE OF IMPLANT
The ideal implant design would be one that would be simple
to place as well as remove, causing minimum discomfort to
the patient. At the same time, they should be optimum in
resisting the conventional Orthodontic forces.
One would be looking at newer designs, which could be
placed by an Orthodontist himself. Also, since the implants
need not last for a very long time, biodegradable implants
may be a lucrative option.
Biodegradable screws made of L-polylactide have been
introduced by Glatzmaier et al and are currently
undergoing clinical trials. The system, termed as theBIOS
(Bioresorbabale implant for Orthodontic systems)consists
of resorbable polylactide with a metal abutment.

Conclusion
Implants for the purpose of conserving anchorage are
welcome additions to the armamentarium of a clinical
Orthodontist.
They help the Orthodontist to overcome the challenge of
unwanted reciprocal tooth movement.
The presently available implant systems are bound to
change and evolve into more patient friendly and
operator convenient designs.
Long-term clinical trials are awaited to establish clinical
guidelines in using implants for both orthodontic and
orthopedic anchorage.


Thank you
Leader in continuing dental education


Implants in orthodontics a paradigm shift /certified fixed orthodontic courses by Indian dental academy

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