Orthodontic implants /certified fixed orthodontic courses by Indian dental academy

Orthodontic Implants
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Orthodontic Implants


Introduction


In 1960s, Brånemark et al noticed the
biocompatibility of titanium screws in bone
tissue. Light microscopic examinations showed
bone-to-implant contact; thus, the concept of
“osseointegration” developed.




After this, many studies were conducted to
investigate the application of titanium implants
in dentistry. An implant success rate of over
90% has been reported in edentulous patients.
Decades before, the idea of using dental
implants to reinforce orthodontic anchorage
showed encouraging results.




Orthodontic anchorage is defined as “resistance
to unwanted tooth movement.” Dentists use
appliances to produce desired movements of
teeth in the dental arch. According to Newton’s
third law of motion, every action has an equal
and opposite reaction; this means that,
inevitably, other teeth move if the appliance
engages them.



Anchorage is the resistance to the force
provided by other teeth or devices. In
orthodontic treatment, reciprocal effects must
be evaluated and controlled. The goal is to
maximize desired tooth movement and
minimize undesirable effects.


HISTORICAL PERSPECTIVE


In 1945, Gainsforth and Higley used vitallium
screws and stainless steel wires in dog mandibles
to apply orthodontic forces. However, the
initiation of force resulted in screw loss. In 1969,
Linkow placed blade implants to anchor rubber
bands to retract teeth, but he never presented
long-term results.






In 1964, Brånemark et al observed a firm
anchorage of titanium to bone with no adverse
tissue response.
In 1969, they demonstrated that titanium
implants were stable over 5 years and
osseointegrated in bone under light microscopic
view. Since then, dental implants have been used
to reconstruct human jaws or as abutments for
dental prostheses. The success has been
attributed to the material, surgical techniques,
and the manner that implants are loaded.



In 1984, Roberts et al corroborated the use of
implants in orthodontic anchorage. Six to 12
weeks after placing titanium screws in rabbit
femurs, a 100-g force was loaded for 4 to 8
weeks by stretching a spring between the screws.
All but 1 of 20 implants remained rigid.
Titanium implants developed osseous contact,
and continuously loaded implants remained
stable. The results indicated that titanium
implants provided firm osseous anchorage for
orthodontics and dentofacial orthopedics.





Retromolar implants were described by Roberts
and colleagues (1990) and the palatal implants
were introduced by Wehrbein and Merz (1998).
Both are used for indirect anchorage, meaning
they are connected to teeth that serve as the
anchorage units.


IMPLANT CRITERIA




Implant materials. The material must be nontoxic
and biocompatible, possess excellent mechanical
properties, and provide resistance to stress,
strain, and corrosion.
Commonly used materials can be divided into 3
categories: biotolerant (stainless steel,
chromium- cobalt alloy), bioinert (titanium,
carbon), and bioactive (hydroxylapatite, ceramic
oxidized aluminum).





Because of titanium’s characteristics (no allergic
and immunological reactions and no neoplasm
formation), it is considered an ideal material and
is widely used.
Bone grows along the titanium oxide surface,
which is formed after contact with air or tissue
fluid. However, pure titanium has less fatigue
strength than titanium alloys. A titanium alloy—
titanium-6 aluminum-4 vanadium— is used to
overcome this disadvantage.



Implant Size The maximum load is proportional
to the total bone-implant contact surface.
Factors that determine the contact area are
length, diameter, shape, and surface design
(rough vs smooth surface, thread configuration).
The ideal fixture size for orthodontic anchorage
remains to be determined. Various sizes of
implants, from “mini implants” (6 mm long, 1.2
mm in diameter) to standard dental implants (615 mm long, 3-5 mm in diameter), have proved
to effectively improve anchorage.



Therefore, the dimension of implants should be
congruent with the bone available at the surgical
site and the treatment plan.




Implant shape. This determines the bone-implant
contact area available for stress transfer and
initial stability. The design must limit surgical
trauma and allow good primary stability. It is
difficult to identify the “perfect” implant shape.
The most commonly used is cylindrical or
cylindrical-conical, with a smooth or threaded
surface. Studies have shown that the degree of
surface roughness is related to the degree of
osseointegration.

Mini implants





Creekmore and Eklund inserted one such device
below the nasal cavity in 1983, but it was not
until 1997 that Kanomi described a mini-implant
specifically designed for the orthodontic use.
These are used as direct anchorage.
In contrast to the osseointegrated implants,
these devices are smaller in diameter and are
designed to be loaded shortly after insertion.

Materials and Design


Most are made from Titanium alloys. The alloy
used for Aarhus Mini Implant is Ti6Al-4V. The
Orthodontic Mini Implant (OMI) [Leone, Italy]
is made from implant steel 1.4441, which is still
used in traumatology.






The diameter of the threaded portion of the
miniscrew varies from 1mm to 2mm. The
advantage of thin screw like Abso-Anchor
[Dentos, Korea] is the ease of insertion between
the roots without the risk of root contact.
The drawback is the potential for fracture, which
is closely related to the diameter of the screw.
(Dalstra M 2004)





As the bone density increases, the resistance
created by the stress surrounding the screw
becomes more important in removal than in
insertion of the screw. At removal the stress is
concentrated at the neck of the screw.
The strength of the screw is optimized by using
a slightly tapered conical shape and solid head
with a screwdriver slot.





The head of the mini implant can be designed
for one point contact with a hole through the
neck, as in Dual Top Anchor System, the
Lin/Liou Orthodontic Mini Anchorage Screw
(LOMAS) and the Spider Screw.
A hook (LOMAS) or a button (Abso-Anchor)
can also be used.






A bracket like head design, on the other hand,
offers the advantage of three dimensional
control and allows the screw to be consolidated
with a tooth to serve as indirect anchorage.
Examples of this type include Aarhus Mini
Implant, Dual Top Anchor System and
Temporary Mini Orthodontic Anchorage
System.





Another design factor is the cut of the threads.
With self drilling mini screws like Aarhus Mini
Implant, Dual Top Anchor System and
LOMAS, the apex of the screw is extremely fine
and sharp, so that the pilot drilling is
unnecessary in most cases.
The transmucosal portion of the neck should be
smooth. It is also important that screws be
available with different neck lengths for various
implant sites.

The Spider Screw




The Spider Screw is a self-tapping miniscrew
available in three lengths—7mm, 9mm, and
11mm—in single-use, sterile packaging.
The screw head has an internal .021" × .
025"slot, an external slot of the same
dimensions, and an .025" round vertical slot. It
comes in three heights to fit soft tissues of
different thicknesses: regular, with a thicker head
and an intermediatelength collar; low profile, with
a thinner head and a longer collar; and low profile
flat, with the same thin head and a shorter collar.





All three types are small enough to avoid softtissue irritation, but wide enough for
orthodontic loading.
The biocompatibility of titanium ensures patient
tolerance, and the Spider Screw’s smooth, selftapping surface permits easy removal at the
completion of treatment.




Because miniscrews rely on mechanical retention
rather than osseointegration for their anchorage,
the orthodontic force should be perpendicular
to the direction of screw placement.




Applied forces can range from 50g to 200g,
depending on the quality of the bone and the
orthodontic movement desired. If any mobility
is noted immediately after placement or during
tooth movement, the screw should be inserted
deeper into the bone, or replaced with a longer
screw to engage the opposite plate of cortical
bone.

Mini Implant Size and Location




The diameter of the mini screw will depend on
the site and the space available. In the maxilla a
narrower implant can be selected if it is to be
placed between the roots.
If stability depends on insertion into the
trabecular bone, a longer screw is needed, but if
the cortical bone will provide enough stability, a
shorter screw can be chosen.



The length of the transmucosal part of the neck
should be selected after assessing the mucosal
thickness of the implant site.






Possible insertion site include, in the Maxilla: the
area below the nasal spine, the palate, the
alveolar process, the infrazygomatic crest, and
the retromolar area.
In the Mandible: the alveolar process, the
retromolar area and the symphysis.


Below the ANS, Palate


Infrazygomatic crest


Retromolar region


Alveolar process, Smphysis






Whenever possible, the mini implant should be
inserted through attached gingiva. If this is not
possible, the screw can be buried beneath the
mucosa so that only a wire, a coil spring, or a
ligature passes through the mucosa.
In the maxilla, the insertion should be at an
oblique angle, in an apical direction; in the
mandible, the screw should be inserted as
parallel to the roots as possible if teeth are
present.

Safety Distance





Huang, Shotwel, Wang (AJODO 2005)
One way to evaluate the possibility of damaging
the periodontal ligament (PDL) is to calculate
the safety distance.
Safety distance: Diameter of the implant + PDL
space (normal range 0.25 mm ± 50%) minimal
distance between implant and tooth (1.5 mm)




Example: Safety distance (mm) of mini-implants
when inserted between roots 1.2 (0.25 + 50%)
(1.5 +1.5) 4.575. Therefore, the distance
between roots needs to be at least 4.6 mm to
reduce the risk.


Safety Distance Modified





Gautam P, Valiathan A (AJODO 2006)
Safety distance: Diameter of the implant + 2 X
[PDL space (normal range 0.25 mm ± 50%)]
minimal distance between implant and tooth (1.5
mm)
Example: Safety distance (mm) of mini-implants
when inserted between roots 1.2 2 X(0.25 +
50%) (1.5 +1.5) 4.9. Therefore, the distance
between roots needs to be at least 5 mm to
reduce the risk.



Insertion



After the local anesthetic is applied, the implant
area is washed with .02% chlorhexidine.
Even when self drilling screws are used, pilot
drilling may be required where the cortex is
thicker than 2mm, as in the retromolar area or
the symphysis, because dense bone can bend the
fine tip of the screw. The pilot drill should be .
2-.3 mm thinner than the screw and should be
inserted to a depth of no more than 2-3mm.





If a manual screwdriver is used for insertion, it is
immediately evident when the a root has been
contacted, and any damage will be minimum. In
tests where notches were intentionally created,
histological analysis showed spontaneous repair
by the formation of cellular cementum.
If the screw is inserted with a low speed drill,
there is a greater chance of not detecting a root
due to lack of tactile sensation.

Zygoma Anchorage
System (ZAS)


Zygoma Anchorage System (ZAS) has been
developed, in which the miniscrews are placed at
a safe distance from the roots of the upper
molars. Because of its location and its solid bone
structure, the inferior border of the
zygomaticomaxillary buttress, between the first
and second molars, is chosen as the implant site.
Combining three miniscrews with a titanium
miniplate can bring the point of force
application near the center of resistance of the
first permanent molar.



The upper part of the Zygoma Anchor is a
titanium miniplate with three holes, slightly
curved to fit against the inferior edge of the
zygomaticomaxillary buttress. A round bar,
1.5mm in diameter, connects the miniplate and
the fixation unit. A cylinder at the end of the bar
has a vertical slot, where an auxiliary wire with a
maximum size of .032" × .032" can be fixed
with a locking screw.



The plate is attached above the molar roots by
three self-tapping titanium miniscrews, each
with a diameter of 2.3mm and a length of 5mm
or 7mm. The miniscrews do not need to be
sandblasted, etched, or coated. Square holes in
the center of the screw heads accommodate a
screwdriver for initial placement, while
pentagonal outer holes are used to remove the
screws at the end of treatment.



To place the anchor, an L-shaped incision,
consisting of a vertical incision mesial to the
inferior crest of the zygomaticomaxillary
buttress and a small horizontal incision at the
border between the mobile and attached gingiva,
is made under local anesthesia. The
mucoperiosteum is elevated, and the upper part
of the anchor is adapted to the curvature of the
bone crest.





Three holes with a diameter of 1.6mm each are
drilled, and the Zygoma Anchor is affixed with
the three miniscrews. The cylinder should
penetrate the attached gingiva in front of the
furcation of the first molar roots at a 90° angle
to the alveolar bone surface.
Orthodontic forces can be applied to the anchor
immediately after implantation.





The ZAS uses three miniscrews, increasing total
anchorage over other types of implants.
Because the miniscrews and miniplate have
excellent mechanical retention, immediate
loading is possible. The point of application of
the orthodontic forces is brought down to the
level of the furcation of the upper first molar
roots.



The vertical slot with the locking screw makes it
possible to attach an auxiliary wire, which can
move the point of force application some
distance from the anchor. The connection
between the anchor and the conventional fixed
appliance can easily be adapted to changing
anchorage needs throughout treatment.
Therefore, the ZAS seems to be an effective
alternative to conventional extraoral anchorage.

Biomechanics: Extraction




In conventional sliding mechanics, the frictional
forces along the canine and the molar region
tend to neutralize each other which may explain
why the overjet is not reduced when the first
molars are used for the posterior anchorage.






On the other hand, when the elastics are
attached from the canine bracket to the
miniscrew or a miniplate in the first molar
region, the distal traction on the archwire
created by friction in the canine bracket is not
counterbalanced by mesial traction from friction
in the molar tube.
The incisors spontaneously follow the
movement of the canine.





The remainder of the overjet and overbite can
easily be corrected with a T- loop arch once the
canines have reached Class I relationship.
The intrusive forces required for bite opening in
the anterior region generate reactive forces,
distal to the T- loops, which tend to cause
canine extrusion.




The Class I relationship in the buccal segment is
maintained by elastic traction between the
canine and the bone anchor, which adds a small
intrusive component of the force to the canines.


Transverse dimension


In conventional
biomechanics, canine
and first molar tend
to rotate in opposite
directions when an
elastic traction is
applied.




In skeletal anchorage
there is no rotation of
the first molar, but
the initial canine
rotation tends to push
the distal end of the
archwire towards the
midline, leading to
crossbite during distal
movement of canine.

Biomechanics: Non Extraction




If anterior teeth are crowded, only a few of the
incisors are bonded to support the anterior
portion of the archwire.
Both upper canines are bonded but the
premolars are not.




After leveling, a sliding jig or a closed coil spring
with a sliding hook is placed on an .016” round
or .016 X .016” SS archwire between each molar
tube and the canine bracket.




With skeletal anchorage, the canines are
distalized along with the molars, helping to
reduce the overjet. This can be explained by the
‘friction hypothesis’.




To avoid rotation of
the first molar around
the palatal root, the
second molars should
always be bonded.






Once the first molars are in Class I relationship,
the premolars and remaining incisors are
bonded.
After a short leveling stage, elastics are attached
from the canines to the bone anchors to close
the remaining space between the canines and the
molars.




Molars are kept in
place with ‘molar
holding springs’- .016
X .022” SS inserted in
the vertical slot of the
bone anchors.




Once spaces in the
buccal segments have
been closed, the
remaining overjet is
corrected and bite is
opened with .016 X .
022 SS T- loop
archwire.

PALATAL IMPLANTS


In 1995, a 2-stage hydroxylapatite-coated
titanium subperiosteal implant (Onplant, Nobel
Biocare, Göteburg, Sweden) was developed.
This system has several characteristics: disc
shaped, 10 mm in diameter, 2 mm thick, coated
with hydroxyapatite on the side against bone,
and smooth titanium facing soft tissue with a
threaded hole where abutments will be placed.



After biointegration with tissue, the disc is
exposed by punch technique (removal of a patch
of tissue at the center). A ball-shaped abutment
is connected, to which orthodontic devices will
be attached. Onplants have been shown, to
provide sufficient anchorage to move and
anchor teeth.




In 1996, a 1-stage endosseous orthodontic
implant for palatal anchorage was presented
(Orthosystem, Straumann). This system has a
diameter of 3.3 mm and endosseous length of 4
or 6 mm. The self-tapping design provides good
initial stability with fewer procedures and less
instrumentation during surgery.




A groove above the transmucosal part can hold
a transpalatal bar (square wire, 0.032 0.032 in,
stainless steel), which can be clamped by a cover
and screwed tightly to the implant. Many studies
have demonstrated its success in maxillary tooth
retraction and stabilization of anchorage teeth.


Optimal site for Palatal Implants


The midsagittal area has relatively low vertical
bone height, and complete ossification of the
suture is rare before 23 years of age (Schlegel et
al 2002). For most adults, osseointegration is
uneventful. However, the paramedian region
might be more optimal for adolescents to avoid
connective tissue of the suture and interaction of
its growth.

Acceptance rate of palatal implants



Gunduz E et al AJODO 2004
In this study, 85 patients who received
orthodontic treatment with palatal implants in 2
clinics in Austria completed questionnaires. The
results show that most patients got used to their
implants in about 2 weeks; 95% were satisfied
with the treatment, and 86% would recommend
the treatment to other patients.



In addition, 75% of the patients found the
orthodontic construction between the anchor
teeth and the palatal implant less comfortable
than the implant itself, whereas 7% found the
palatal implant less comfortable. Approximately
24 months of treatment with the palatal implant
is tolerable for patients; this is the average
orthodontic treatment time.

Anchorage effect of various shape
palatal osseointegrated implants



Chen F, Terada K, Handa K.
The purpose of this study was to compare the
anchorage effects of different palatal
osseointegrated implants using a finite element
analysis. Three types of cylinder implants (simple
implant, step implant, screw implant) were
investigated. Three finite element models were
constructed.



Each consisted of two maxillary second
premolars, their associated periodontal ligament
(PDL) and alveolar bones, palatal bone, palatal
implant, and a transpalatal arch. Another model
without an implant was used for comparison.
The horizontal force (mesial 5N, palatal 1N) was
loaded at the buccal bracket of each second
premolar, and the stress in the PDL, implant,
and implant surrounding bone was calculated.



The results showed that the palatal implant
could significantly reduce von Mises stress in the
PDL (maximum von Mises stress was reduced
24.3-27.7%). The von Mises stress magnitude in
the PDL was almost same in the three models
with implants. The stress in the implant
surrounding bone was very low. These results
suggested that the implant is a useful tool for
increasing anchorage. Adding a step is useful to
lower the stress in the implant and surrounding
bone, but adding a screw to a cylinder implant
had little advantage in increasing the anchorage
effect.

Anchorage Effect of Osseointegrated vs
Nonosseointegrated Palatal Implants.




Chen F, Terada K, Hanada K, Saito I. Angle
Orthod. 2006
The purpose of this study was to compare the
anchorage effects of an osseointegrated palatal
implant (OPI) with a nonosseointegrated palatal
implant (NOPI), using finite element analysis.
One model, which was composed of two
maxillary premolars, periodontal ligament
(PDL), alveolar bone, a palatal implant, palatal
bone, a bracket, band, and TPA, was created on
the basis of the clinical situation.



The palatal implant was treated as either NOPI
or OPI. The force on the premolars was
investigated under three conditions: a
mesiodistal horizontal force, a buccolingual
horizontal force, and a vertical intrusive force.
The PDL stress was calculated and compared
with a model without an implant.




The result showed that OPI could reduce PDL
stress significantly. (The average stress was
reduced by 14.44% for the mesiodistal
horizontal force, 60.28% for the buccolingual
horizontal force, and 17.31% for the vertical
intrusive force.) The NOPI showed almost the
same anchorage effect as OPI.




The stress on the NOPI surface was higher than
that on the OPI surface, but the stress was not
high enough to result in failure of the implant.
These results suggested that waiting for
osseointegration might be unnecessary for an
orthodontic implant.


Anchorage loss of the molars with and without
the use of implant anchorage
 Thiruvenkatachari B, Pavithranand A,
Rajasigamani K, Kyung HM.(AJODO 2006)
 The purpose of this study was to compare and
measure the amount of anchorage loss with
titanium microimplants and conventional molar
anchorage during canine retraction.
METHODS: Subjects for this study comprised
10 orthodontic patients (7 women, 3 men) with
a mean age of 19.6 years (range, 18 to 25 years),
who had therapeutic extraction of all first
premolars.



After leveling and aligning, titanium
microimplants 1.3 mm in diameter and 9 mm in
length were placed between the roots of the
second premolars and the first molars. Implants
were placed in the maxillary and mandibular
arches on 1 side in 8 patients and in the maxilla
only in 2 patients.




After 15 days, the implants and the molars were
loaded with closed-coil springs for canine
retraction. Lateral cephalograms were taken
before and after retraction, and the tracings were
superimposed to assess anchorage loss.




The amount of molar anchorage loss was
measured from pterygoid vertical in the maxilla
and sella-nasion perpendicular in the mandible.
RESULTS: Mean anchorage losses were 1.60
mm in the maxilla and 1.70 mm in the mandible
on the molar anchorage side; no anchorage loss
occurred on the implant side. CONCLUSIONS:
Titanium microimplants can function as simple
and efficient anchors for canine retraction when
maximum anchorage is desired.

Implant surface geometry and its
effect on regional bone remodeling.




Oyonarte R, Pilliar RM, Deporter D,
Woodside DG
Bone response to orthodontic loading was
compared around 2 different types of
osseointegrated implants (porous surfaced and
machined threaded) to determine the effect of
implant surface geometry on regional bone
remodeling.



METHODS: Five beagles each received 3 implants of
each design in contralateral mandibular extraction sites.
After a 6-week initial healing period, abutments were
placed, and, 1 week later, the 2 mesial implants on each
side were orthodontically loaded for 22 weeks. All
implants remained osseointegrated throughout
orthodontic loading except for 1 threaded implant that
loosened. Back-scattered scanning electron microscopy
and fluorochrome bone labeling techniques were used
to compare responses around the 2 types of implants.



RESULTS: The loaded, porous-surfaced
implants had significantly higher marginal bone
levels and greater bone-to-implant contact than
did the machined-threaded implants.
CONCLUSIONS: Significant differences in
peri-implant bone remodeling and bone
formation in response to controlled orthodontic
loading were observed for the 2 implant designs.
Short, porous-surfaced implants might be more
effective for orthodontic applications than
machine-threaded implants

SURGERY AND HEALING TIME




If implants are planned for future prosthetic
abutments, a standard healing protocol should
be followed.
Direct orthodontic forces generate less stress on
implants due to limited force imposed ( 3N,
about 300 g). The stress is far less for indirect
anchorage because implants are used to stabilize
teeth.





During surgery, assessment of bone quality and
initial implant stability are important. With dense
bone and satisfactory stability, immediate
loading might be feasible.
Threaded implants provide superior mechanical
interlock as compared with cylindrical designs.
Thus, waiting time should be longer for
nonthreaded implants.



Complete osseointegration is favorable but not
essential for effective orthodontic anchorage
implants. However, stable mechanical retention
or partial osseointegration is required, and
implants should not be overloaded during
healing.




Ohmae et al, 2001 reported a study on Dog jaws
in which Titanium mini-implant were loaded
using 150g force for12-18 wks after 6 wks
healing period. All implants remained stable.
Periimplant bone at loaded implants was equal
to or slightly greater than unloaded ones.








Trisi and Rebaudi, 2002 reported on Human
Titanium (Biaggini, Ormco) implants.
Force of 80-120g/8-48 wks was applied after 8
wks healing period.
All implants remained stable and
osseointegrated. Bone remodeling around
implants was observed.





Akin-Nergiz et al,1998
Orthopedic force (2 N/12 wks- 5N/24) after
healing period of 12wks was applied on Dog
jaws using Titanium (ITI) implants). Implants
had no displacement for any force level.




Deguchi T, et al (J Dent Res. 2003) quantified
the histomorphometric properties of the boneimplant interface to analyze the use of small
titanium screws as an orthodontic anchorage
and to establish an adequate healing period.
Overall, successful rigid osseous fixation was
achieved by 97% of the 96 implants placed in 8
dogs and 100% of the elastomeric chain-loaded
implants.



All of the loaded implants remained integrated.
Mandibular implants had significantly higher
bone-implant contact than maxillary implants.
Within each arch, the significant
histomorphometric indices noted for the "threeweek unloaded" healing group were: increased
labeling incidence, higher woven-to-lamellarbone ratio, and increased osseous contact.




Analysis of these data indicates that small
titanium screws were able to function as
rigid osseous anchorage against
orthodontic load for 3 months with a
minimal (under 3 weeks) healing period.


DISADVANTAGES OF USING DENTAL
IMPLANTS


Disadvantages include longer treatment time,
financial concerns, and anatomical limitations.
However, the benefit from superior anchorage
and time saved by using implant anchorage
often exceeds the healing time after surgery.




Implant surgery does cost more than other
treatments. If implants will be used in the
prosthetic treatment plan, the fee is offset. In
addition, implant anchorage reduces the risk of
jeopardizing existing dentition. Application of
implants might be limited by the amount and
quality of bone. Therefore, thorough evaluation
is critical before treatment.

INDICATIONS


Intrude/extrude teeth. It is difficult to intrude
or extrude teeth, particularly molars. Implant
anchorage greatly facilitates these movements.
Mini-implants (1.2 mm in diameter, 6 mm in
length), which can be placed between roots or
apical to a tooth, are more feasible. Pure
intrusion or extrusion cannot be achieved. If the
implant is at the facial side for intrusion, only
intrusion plus protrusion can be accomplished.
Also, care should be taken not to involve the
periodontal ligament and prevent postoperative
peri-implant mucositis,

Miniscrews for Molar Intrusion


Close edentulous spaces. Missing first molars
or congenital missing teeth are common.
Because of reduced anchorage, implants in
retromolar areas have been used to translate
teeth into edentulous areas.
 Titanium screws can be placed to protract
molars and close the spaces of congenital
missing premolars.



Miniscrews for Molar Protraction






This treatment is superior to others when
adjacent teeth are intact or have large pulp
chambers, making preparation undesirable.
Plaque control is more complicated with fixed
partial dentures, which increase the risk of caries
and endodontic or periodontal disease.
If the translated tooth is tipped, it should be
uprighted to prevent a mesial angular bony
defect.



Reposition malposed teeth. Preprosthetic
corrections of tilted abutments are not unusual.
Adequate anchorage for tooth movement is
often impossible when there are several missing
teeth. Realignment of molars by using the
remaining teeth is complicated because of
limited support. Implants facilitate uprighting
the abutment teeth at the end of a long
edentulous ridge. If carefully planned, dental
implants used to upright teeth can be restored as
implant-supported prostheses in edentulous
areas.

Uprighting tipped Molars




Reinforce anchorage. Palatal implants have
been developed to reinforce anchorage. An
endosseous orthodontic implant anchor system
(Orthosystem, Straumann, Waldenburg,
Switzerland) has been designed and can be used
in Class II malocclusion patients in whom no
extraction or extraction of maxillary first
premolars and retraction of anterior teeth are
planned.

Group distal movement of teeth using
microscrew implant anchorage



Park HS, Lee SK, Kwon OW Angle Orthod.
2005
The purpose of this study was to quantify the
treatment effects of distalization of the maxillary
and mandibular molars using microscrew
implants. The success rate and clinical
considerations in the use of the microscrew
implants were also evaluated. Thirteen patients
who had undergone distalization of the posterior
teeth using forces applied against microscrew
implants were selected.



Among them, 11 patients had mandibular
microscrew implants and four patients had
maxillary implants, including two patients who
had both maxillary and mandibular ones at the
same time. The maxillary first premolar and first
molars showed significant distal movement, with
no significant distal movement of the anterior
teeth.



The mandibular first premolar and first and
second molars showed significant distal
movement, but no significant movement of the
mandibular incisor was observed. The
microscrew implant success rate was 90% over a
mean application period of 12.3 +/- 5.7 months.
The results might support the use of the
microscrew implants as an anchorage for group
distal movement of the teeth.

Treat partial edentulism. Treatment is
complicated in patients with malocclusion and
many missing and periodontally compromised
teeth. Fortunately, implants in edentulous areas
to provide orthodontic anchorage and later serve
as prosthetic abutments have been considered a
proper interdisciplinary approach.
 Transitional implants have been applied in these
situations.





Correct undesirable occlusion. Correcting
Class III anterior crossbite with conventional
methods is not always satisfactory. Retracting
the entire mandibular arch with dental implants
is possible. Localized crossbite can be treated by
bonding implants and teeth to avoid full-mouth
treatment. Protracting maxillary arches can be
achieved by using implant anchorage.



Provide orthopedic anchorage. Palatal
implants can be used to elicit palatal expansion.
This applies to partially edentulous patients or
children with congenital diseases that result in
facial developmental defects or missing teeth.
Implants in congenital anomalies can promote
orthodontic and orthopedic therapy and
accelerate jaw movement by sutural distraction.

IMPLANTS AS ANCHORS FOR ORTHOPEDIC
APPLICATIONS






In orthopedic treatment the forces are
transmitted to the bones by a tooth; this implies
skeletal as well as dental effects.
Tooth splinting or controlling force vectors can
minimize undesirable movement, but it cannot
be avoided. Skeletal movement can be
accomplished by using teeth as anchorage, but
dental side effects often limit the amount of
movement.
Implants can overcome the limitations by
guiding forces directly to the bones.





Facial skeletal movement by implant anchorage
has also been evaluated. (Smalley et al 1988)
A 600-g force was applied until 8 mm of
maxillary displacement occurred. All implants
remained stable over 12 to 18 weeks. The
findings also showed the possibility of
controlling the direction of protraction.






To evaluate the application of implants in
sutural expansion, animal studies have been
conducted. (Parr JA et al 1997)
Two titanium implants were placed on either
side of the internasal suture in 18 rabbits, which
were divided into an unloaded control group
and 2 test groups. After 8 weeks, each test group
was loaded with a force of 1 Newton (N) or 3
N. All implants remained stable for 12 weeks.



Several congenital facial anomalies and
developmental defects present anchorage
challenges. Case reports using dental implants
for orthopedic movement and acceleration of
jaw movement by sutural distraction have been
reported. Nonetheless, the optimal load, which
has not been determined yet, for sutural
expansion is the lowest above the woven bone
threshold that effectively separates it. Therefore,
further studies are needed to determine the
optimal load.

Transitional Implants
 While

endosseous dental implants are
intended to resist the heavy, intermittent
forces of occlusion, orthodontic forces
are considerably lower and more
sustained. Therefore, the requirements
of an orthodontic anchor implant may
be quite different.

The titanium Modular Transitional Implant




The Modular Transitional Implant, 1.8mm in
diameter, is available in lengths of 14mm,
17mm, and 21mm. It was designed to support a
temporary fixed prosthesis during the healing
phase associated with placement of permanent
implants, and to be removed when the
permanent implants are restored.


Conclusion




Currently, dental implants have become
predictable and reliable adjuncts for oral
rehabilitation.
Osseointegrated/ Non osseointegrated implants
can be used to provide rigid orthodontic or
orthopedic anchorage. Although initial results
are encouraging, the risks and benefits must be
thoroughly evaluated.



In the future, as developments occur in the
implant technology, they may have a significant
role as anchorage reinforcement aids.


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

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Irfan Dawoodbhoy, Valiathan Ashima:
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



Drago CJ. Use of osseointegrated implants in
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Wehrbein H. Feifel H. Diedrich P. Palatal
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



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

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Deguchi T, Takano-Yamamoto T, Kanomi R,
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

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

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

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