Transcript Temporary Anchorage Devices - Huntington Beach Oral and

Temporary Anchorage Devices
David R. Telles, DDS
Diplomate of the American
Board of Oral and Maxillofacial
Surgery
Introduction
•
•
•
•
•
•
•
•
Overview
Orthodontics
History
Conventional Mechanics
Anchorage types
Clinical Indications
Surgical Techniques
Outcomes / Complications
Overview
• Orthodontists have always tried to develop ways to
move teeth while minimizing the unwanted
reciprocal movement of the teeth they pull or push
against
• Best situation when ideal anchorage is in place to
move teeth in an efficient manner
• History:
▫ Use of dental implants
▫ Unpopular due to
 Time for osteointegration
 Use for restoration purposes
 Cost
Orthodontics
• Goals of therapy
▫ Optimization of occlusion
▫ Aesthestics
▫ Facial Balance
• Traditional ortho can accomplish which require mild
to moderate compensation
▫ More significant discrepancies require more robust
anchorage
 E.g. pts with moderate to severe skeletal discrepencies –
may requiring growth modifcation or orthognatic Sx
▫ May benefit from skeletal anchorage – I.e. cases to
which conventional orthodontics cannot correct severe
malocclusions
History
• Concept for using implantable devices for skeletal anchorage has
been present for that last ½ century
• 1940: Gainsforth and Higley experimented with vitallium screws
and wires in a dog ramus for anchorage
• Linkow used blade implants to provide class II elastics
• Sherman et. al. used dental implants in dogs for anchorage with
limited success
• 1979: Smith noted implants could act as ankylosed teeth for
orthodontic movements
• 1988: Shapiro et. al. established the use of dental implants for
orthodontic anchorage
• 1995: Block et. al. used HA coated onplant placed in the midline
palatal tissue for use with orthodontics for anchorage
• 1999: Umemori et. Al described techniques for using a modified
rigid fixation plate for use with orthodontics – important leap
forward since force could be applied without loosening the plates
Orthodontics mechanics and skeletal
anchorage
•
•
•
•
Planning requires a team approach
Anchorage: resistance to unwanted tooth movement
forces involved
In orthodontic tooth movement – it obeys Newton’s third law
▫ for every action, there is an equal and opposite reaction -- every
movement of a tooth in the desired direction, the force is
distributed to the anchorage segment, potentially affecting the
position of those teeth within the anchorage segment
• Example
▫ To move a canine posterior (distally) and if only one molar is
present, then the molar has a tendency to drift toward the mesial
if the molar is used as an anchor for that movement
▫ If more anchorage is provided to that area  then the movement
can occur with less of the unwanted mesial movement of the
molar
Using Conventional Mechanics
• anchorage can be increased by using intraoral or extraoral
techniques
• Intraoral techniques commonly use tooth-borne appliances to
improve anchorage.
▫ increasing the number of teeth in the anchorage unit
 E.g. teeth can be tied together with ligature wire to resist unwanted tooth
movement in another area
▫ Another way of increasing teeth in the anchorage segment is to use a
transpalatal arch.
 distributes the force to another segment of teeth across the arch.
▫ elastic bands can be used between the opposing arches to provide
additional anchorage
 used to close space after maxillary premolar extraction by retracting the
anterior dentition of the maxilla with elastic bands bilaterally and
attaching the elastic to the
 mandibular posterior teeth
 AKA class II elastics help to minimize the unwanted mesial movement of
the maxillary posterior anchorage segments.
Using Conventional Mechanics
• Nance button appliance that holds the posterior
molars in position with an acrylic button on the
anterior palate
▫ Force can be applied to the posterior teeth to close
premolar space
▫ Helps to offset the tendency for the molar teeth to
move mesial is resisted by the acrylic button on the
palate near the incisive foramen
• Extraoral Appliances
▫ Significantly dependent on compliance of the pt
▫ Rarely provide force > 6-10 hrs/day
▫ E.g. Head Gear
Skeletal Appliances
• Provide anchorage not tooth-borne
• Unwanted reciprocal tooth movement avoided
• Other adv:
▫
▫
▫
▫
No or minimal reliance on existing dentition
Less dependent on patient compliance
Continuous rather than intermittent force may be applied
Surgical procedures are necessary, but they are simple in
most instances
▫ May be significantly less expensive than other surgical
options, such as orthognathic surgery
▫ Force may be applied very soon or immediately after
placement of the device; devices require mechanical
stability rather than osteointegration
▫ Devices are easily removed
Anchorage types
• Direct –
▫ Apply force directly from the anchor to the segment or tooth that is being moved
▫ E.g. maxillary plates placed in the zygomatic butress may be designed to provide
intrusion force to maxillary molars to close anterior open bites
• Indirect
▫ Tie the anchor device to the segment of teeth that requires additional anchorage
such that more traditional mechanics can be used in the area
▫ Involves an inelastic or even rigid connection between the anchor and the
orthodontic appliances
▫ E.g. maxillary anchor tied by steel ligature to the anterior teeth to provide more
anchorage – then a coil spring could be used on the archwire to distalize the molar
teeth
 Indirect due to the force used is along the archwire by the coil spring
▫ ADV:
 Most orthodontists already design their movements of teeth based on traditional
mechanics
• Either technique can accomplish similar outcomes – help to allow
orthodontic movements which once were deemed difficult or impossible
Take note
• Skeletal anchorage devices do not allow faster
movement of teeth, or the ability to overcome
exceptionally large discrepancies
• the devices have limitations
• Provide absolute anchorage for orthodontic
movement
Devices for skeletal anchorage
• Dental Implants
▫ Costly, Reqs OI
▫ Requires aggressive Sx for removal
• Mini dental implants
• Onplant
▫ Placed in midpalatal region
▫ Long-term studies not documented
• Bone screws
▫ Self-tapping and self-drilling systems available
▫ Bicortical screws 8-12 mm in length
▫ Stability determined by thread pitch based on bone
type – typically 0.6 mm
Devices for skeletal anchorage
• Devices should –
▫ Be designed for the purpose of skeletal orthodontic
anchorage
▫ Have a very high quality of manufacturing with
standardized quality control
▫ Have an appropriate pitch thread to ideally engage bone
▫ Have the appropriate core and external diameter to
withstand orthodontic forces in maxillary and mandibular
bone
▫ Be designed well at the runout and shafthead interface to
avoid fracture
• Screws smaller than 1.5 mm tend to fail and not
recommended
• Bracket head screws offer little adv
Devices for skeletal anchorage
• Skeletal anchorage plates
▫
▫
▫
▫
▫
Adv: incresed stability, 3D support
Are modified leforte osteotomy plates
Do no require osteointegration
May be immediately loaded
Allow placement of multiple screws away from
vital anatomical structures
Clinical Indications
• Mesial or distal Movement of Teeth with
maximum anchorage
• Uprighting or intruding molar teeth
• Closure of anterior open bite
• Orthopedic growth modification
Clinical Indications
• Mesial or distal Movement of
Teeth with maximum anchorage
▫ e.g. loss of 1st molar – moving
teeth anteriorly – to prevent
movement of anterior teeth
distally a skeletal anchor can be |
used
 Can prevent inadvertent movement canine relationship
to class II
 Helps maintain overbite-overjet relationship
▫ E.g. Class III pt can have posterior mandibular teeth
stabilized and compensate mand ant teeth and hold
posterior teeth to prevent mesial tipping of molars OR
to provide anchorage to distalize molar teeth
Clinical Indications
• Mesial or distal
Movement of Teeth
with maximum
anchorage
Clinical Indications
• Uprighting or intruding molar teeth
▫ Considered one of the more difficult movements
in ortho e.g. molar moving mesially post-extration
▫ Use of a skeletal anchor can help uprighten
without extrusion which results typically with
conventional orthodontics
▫ Intrusion also can be accomplished with skel
anchorage
Clinical Indications
• Closure of anterior open bite
▫ Accomplished via placement of orthodontic screws
or plates in the posterior maxilla, apical to the
dentition
▫ Force is generated to intrude the posterior molars
and premolars to close the anterior openbite
 Numerous case reports show success
 No long term data on stability compared to
orthognathic surgery
 Should be reserved to pts not willing to undergo
orthognathic Sx
Clinical Indications
• Orthopedic growth modification
▫ Can be used in a manner similar to headgear
▫ Considered to be used in phase I of orthodontic Tx
▫ For pts with Class III
 Skeletal anchors can be placed in the maxilla/mandible to
provide forward orthopedic force to the maxilla and
encourage class I relationship
 Vector of force similar to reverse-pull headgear w/o need
for external appliance therapy
▫ Limited use due to risk of growing/developing
dentition and risk of multiple surgical procedures on
pediatric pt
Surgical Techniques
• The type of anchor (miniscrew, anchor plate),
location, angle of the device is determined by the
orthodontic Tx plan
Placement of Skeletal Anchorage
plates
• devices typically consist of a bone plate with holes for screw
placement and a transmucosal connecting arm that extends from
the plate to a specialized working end
• working end -- allows for the attachment of wire, springs, elastics,
and other orthodontic constructs
• Placement typically carried out under local anesthesia
• Monocortical screws
• Maxilla
▫ Typically placed within one of the vertical butresses of the midface
(zygomaticomaxillary, piriform rim)
▫ transmucosal position of the connecting bar should be located at
approximately
▫ the mucogingival junction
▫ Nonkeratinized mucosal tissues should be avoided
 NOTE: When the transmucosal location of the connecting bar is within the
unattached tissues of the maxillary vestibule, increased irritation,
inflammation, infection, and soft tissue overgrowth may result.
Placement of Skeletal Anchorage
plates
• Mandible
▫ Avoid IAN, mental nerve, teeth roots
▫ Typically placed in the symphysis, ramus,
posterior body of the mandible
▫ If bone plate positioned directly over mandibular
canal – use of monocortical screws helps avoid
injury to the IAN
Placement of miniscrews
•
•
•
•
Similar to placing IMF screws
Placed near or @ the mucogingival junction
To engage the cortical and cancellous bone
Longest length possible while avoiding vital anatomical
structures
• Maxilla
▫ Zygomatic or piriform butress
▫ Hard palate
▫ Alveolar process between teeth
• Mandible
▫ Between teeth
▫ Symphysis
▫ Retromolar pad
• Does not require elevation of a soft tissue flap
Post-op
• Post-op imaging to confirm placement and
proximity to anatomy
• Abx x 5-7 days – pen, amox, clinda, etc.
• Encourage OH
• Prescribe CHG bid x 7 days
• Cheek irritation seen peeking @ POD #10
• May be immediately used following surgical
placement both miniscrews + plates
▫ Manipulation with full orthodontic forces typically
delayed 7-10 days post-op to allow for adequate
healing @ the Sx site/ soft tissue
Outcomes + Complications
• Outcomes vary based on screw or plate systems
• A number of reports have listed loosening or outright failure of
orthodontic anchorage screws to be above 15%.
• Rate of failure of plates < 5%
• Prospective unbias literature still required
• Complicaitons
▫
▫
▫
▫
Device failure
Loosening associated with design flaw
Infection
Operator related complications:






Stripping of screws
Overworking screw
Poor stability due to poor choice of placement
Failure to place working attachments through attached mucosa
Misplacement for use by orthodontist
Root damage to teeth – typically seen with discomfort during mastication
Outcomes + Complications
• Patient related complications
▫ Poor quality bone
▫ Reasonable OH
▫ Systemic disordered affecting bone or mucosal
healing
▫ Previous Hx of radiation therapy to the H & N
region
▫ Hx of bisphosphonate use
▫ Smokers
References
• Costello, B. Oral Maxillofacial Surg Clin N Am 22 (2010) 91–105
• Park HS, Kim JB. The use of titanium microscrew implant as orthodontic
anchorage. Keimyung Med J 1999;18:509–15.
• Park HS, Bae SM, Kyung HM, et al. Microimplant anchorage for treatment
of skeletal class I bialveolar protrusion. J Clin Orthod 2001;35:417–22.
• Umemori M, Sugawara J, Mitani H, et al. Skeletal anchorage system for
open-bite correction. Am J Orthod Dentofacial Orthop 1999;115:166–74.
• Sugawara J. Dr. Junji Sugawara on the skeletal anchorage system. J Clin
Orthod 1999;33:689–96.
• Bae SM, Park HS, Kyung HM, et al. Clinical application of micro-implant
anchorage. J Clin Orthod 2002; 36:298–302.
• Gainsforth BL, Higley LB. A study of orthodontic anchorage possibilities in
basal bone. Am J Orthod 1945;31:406–17.
• Linkow LI. The endosseous blade implant and its use in orthodontics. J
Orthod 1969;18:149–54.
• Sherman AJ. Bone reaction to orthodontic forces on vitreous carbon dental
implants. Am J Orthod 1978; 74:79–87.