orthodontic mechanics uesd in treatment of impacted maxillary canine and piggyback technique

1. ORTHODONTIC DEPARTMENT,
MANSOURA UNIVERSITY, EGYPT

2.  Impacted tooth is one that fails to erupt and will not
attain its anatomical position beyond the chronological
eruption date even after its root completion.

3.  Canines are important both esthetically and functionally
 The incidence of canine impaction is 2:1 females to
males respectively .
 Palatally impacted in 85% of patients and buccally
in15%.
 Impacted canine should located precisely by CBCT.

4.  improper mechanics (direction and magnitude of force
applied) when treating impacted and ectopically erupted
canines increases the chance of root resorption of the
adjacent teeth.

5. 1. Clinical Examination : The following clinical signs along with
radiographic diagnosis might be indicative of impacted canines.
 Delayed eruption or migration of the permanent maxillary lateral
incisors
 Delayed eruption of the permanent canine (beyond 14 to 15 years
of age)
 Prolonged retention of the deciduous canine (beyond 14 to 15
years of age)
 Absence of normal canine bulge
 Presence of palatal bulge
2. Radiographic Diagnosis
A) Periapical films B) Occlusal films C) CBCI

6.  arch length deficiency (buccal canine impactions).
 disturbances in tooth eruption sequence (hormonal or
disease induced).
 Palatally impacted canines are often present with
adequate arch space whereas buccally impacted canines are
thought to be associated with dental arch deficiencies. R.Nanda

7.  trauma to the maxilla or maxillary dentition.
 rotation of tooth buds
 prolonged retention of deciduous canine.

8.  Pathological lesions such as cysts
 Absence of maxillary lateral incisor
 Dilaceration of the root
 Heredity

9.  Guidance theory : Canine erupts along the root of lateral
incisors, which serve as a guide, and if the lateral incisor is
absent or malformed, the canine will not erupt.
 Genetic theory : Genetic factors are primary origin of
palatally displaced maxillary canine and include other
possibly associated dental anomalies, such as missing or
small lateral incisor.

10.  Indicated when tooth does not erupt spontaneously after
creating space in the arch.

11.  Two schools of thought exist : open or closed eruption
technique.
 Open eruption technique:
# Excisional approach: Canine crown coronal to mucogingival
junction.
gold chain

12.  Open eruption technique:
# Apically positioned flap : Canine crown apical to
mucogingival junction .

13.  Open eruption technique: A simple palatal impaction (cusp
tip of the canine at the same level of the cemento-enamel
junction of lateral incisor or central incisor) usually
requires open surgical exposure.

14.  closed surgical technique : Is usually favored when the
tooth is more deeply embedded in the bone since open
surgical exposure may necessitate excessive removal of the
surrounding bone.
Ligature wire

15. The tunnel approach : A modification of the closed
surgical technique.
 buccal flap is raised from the attached gingival at the neck
of the deciduous canine and adjacent teeth.

16. The tunnel approach :
 expose the surface of alveolar bone up to and including that covering
the labially impacted canine.
 The buccal crown surface of the canine is exposed and the deciduous
canine extracted. The twisted ligature wire or gold chain linked to the
eyelet, which is bonded to the tooth, is threaded into the apical area of
the socket of the deciduous canine and drawn downward to exit
through its coronal end with no buccal bone is removed, the flap is
sutured back, leaving only the end of the ligature/gold chain visible
through the socket of the deciduous canine.
Ligaturewire

17.  Since a displaced or impacted tooth is only accessible by
means of a surgical intervention, a traction element on a
tooth must be fixed as carefully as possible in order to
prevent a second operation.

18.  Cantilever springs (0.017 x 0.025 inch) with a single force
direction and point of force application are commonly used
for the management of impacted and ectopically erupted
canines.

19.  Cantilever springs produce force on the impacted and
ectopically placed canines in all three spatial planes,
depending on the position of the canine.

20.  The major force directed on the impacted and ectopically
placed canine is vertical (extrusive force) and labial/lingual.
 force systems delivered by these appliances tend to stay
optimal and consistent in their magnitude.
 range between 35 - 60 gm.

21.  The reactionary force and the moment are dissipated on the
molar, which can be controlled by using a palatal arch and
or ligating the molar to the rest of the arch.

22.  Use of light force to move impacted tooth; not more
than 2 ounces (60 gm)
 Availability or creation of sufficient space in the arch for
impacted tooth.
Canting of occlusal plane

23.  Maintenance of the space either by continuous tying
of the teeth or placement of a passive open coiled spring
on the arch wire.

24.  Provision by the arch wire of sufficient stiffness (e.g.
0.018 x 0.022) to resist deformation by the forces applied
to it as the canine is extruded.

25.  A 13-year-old girl with a chief complaint of crooked
anterior teeth.
 Intraoral examination showed that she had a bilateral Class I
molar relationship and palatally impacted maxillary canines

26.  After leveling and aligning, a 0.032-inch CNA (Connecticut
new arch form, Ortho Organizers, Carlsbad, CA.)transpalatal
arch and a 0.019 x 0.025-inch CNA archwire were placed in
the maxillary arch.

27.  Cantilever springs (0.017 x 0.025-inch CAN wire) applying
80 gm. of force (occlusally/extrusive) were placed
bilaterally from the auxiliary tube of the molar bands.

28.  Springs were activated at each visit and after 5 months
maxillary canines erupted in the oral cavity.
 Then, the direction of the force was changed from occlusal
to bucco-occlusal and force was reduced to 30 gm.
 After 12 months, the crowns of both maxillary canines were
in the arch

29.  Finishing and detailing were accomplished with a 0.017-x
0.025-inch CNA archwire.

30.  A 12-year-old girl with a chief complaint of irregularly
placed upper front teeth.
 Intraoral examination showed that she had a bilateral Class I
molar relationship and highly placed maxillary canines in
the buccal vestibule .

31.  The deciduous maxillary left canine was over retained and
the patient had a crossbite tendency due to a narrow
transverse maxillary dimension .

32.  The deciduous left maxillary canine was extracted and a
hyrax expander was placed to correct the transverse
discrepancy.

33.  Cantilevers (0.017 x 0.025-inch CNA) were placed
bilaterally from the auxiliary tube of the molar bracket to
bring the highly placed canines into the arch.
Cantilevers spring

34.  Further alignment of the canines was done using a 0.016-
inch (Ni-Ti) wire piggybacked over a stiffer 0.017 x 0.025-
inch CNA base archwire.

35.  Finishing and detailing were accomplished with a 0.017 x
0.025-inch CNA .
 Total treatment time was 15 months .

36.  The Kilroy Spring, introduced in 2003.
 It is a constant force module that delivers slow and
continuous force which slid onto a rectangular archwire
over the site of palatally impacted canine without the need
for patient compliance.

37.  In the passive state, the vertical loop of the Kilroy Spring
extends perpendicularly from the occlusal plane.

38.  To activate the spring, a stainless steel ligature is guided
through the helix at the apex of the vertical loop, and the
loop is directed toward the impacted tooth.
 The ligature is then tied to an attachment that has been
direct-bonded to the surgically exposed tooth

39.  The amount of force generated by the Kilroy Spring can
be increased or decreased by bending the vertical loop
toward or away from the impacted tooth by holding one
helical loop with a bird-beak plier, bending one leg of the
vertical loop in the desired direction .

40.  The direction of force is also adjustable.
 For example, if a more lateral force vector is desired or
the vertical loop of the Kilroy Spring needs to be
shortened to fit a particular situation, the terminal helix of
the vertical loop can be “folded over” back onto itself .

41.  Because of the inherent flexibility in its design, the Kilroy
Spring will typically fit the available arch space whether
the final destination of the impacted tooth is wider or
narrower than the tooth itself.
 the vertical loop of the Kilroy Spring can be adjusted to
produce a light force to assist in closing, maintaining, or
opening space.

42.  A Kilroy Spring can be tied to a Monkey Hook, loop-
button or a gold chain.

43.  Support for the activated Kilroy Spring is derived from the
continuous rectangular archwire and reciprocal forces from
the incisal third of the adjacent teeth, which are contacted by
the lateral extensions of the spring.
 both lateral and vertical eruptive forces are directed to the
impacted tooth .

44.  The Spring may need to be periodically retied to maintain
a constant force as the tooth erupts .
 The spring is removed once the tooth is sufficiently
erupted.
 Then, bracket or a new loop-button is then bonded to the
tooth to continue moving it into the arch

45.  13-year-old female patient with palatally impacted right canine.
 After surgical exposure, Kilroy Spring ligated to bonded loop-
button on canine in conjunction with typical continuous-arch
mechanics.
 Lateral and vertical displacement of canine after one month.
 Canine slightly over-erupted after two months.

46.  Thermally activated super-elastic rectangular wire slid through loop-
button to continue buccal movement of canine.
 0.018" stainless steel archwire placed one month later to move
canine buccally .
 Bracket bonded to canine five months after surgical exposure.

47.  Compliance Spring slid onto round archwire and secured in
vertical bracket slot and intermaxillary elastic used to activate spring
for labial root torque.
 ProFlex silicone tooth positioner delivered immediately after
removal of fixed appliances and worn full-time for one week to
finalize occlusion and improve gingival health.
 Patient after 21 months of treatment.

48.  12-year-old female patient with palatally impacted right canine.
 After surgical exposure and placement of bonded loop-button,
Monkey Hook with elastic chain and intermaxillary elastic used to
initiate movement.
 Kilroy Spring slid onto rectangular archwire and ligated to canine
eight months later.

49.  After 23 months of treatment.
 Second attachment bonded to disto-buccal surface of canine, and
two Monkey Hooks with elastic chains connected to attachments to
produce rotational couple.

50.  After one month of rotation.
 Bracket bonded to canine after four months of rotation.

51.  Patient after 39 months of total active treatment.

52.  The Kilroy II Spring was designed to produce more vertical than
lateral eruptive forces for eruption of buccally impacted teeth.
 Its multiple helices increase its flexibility,
but also increase the likelihood
of impingement on the soft tissue.

53.  22-year-old female who had undergone previous
orthodontic treatment, but still had impacted maxillary left
permanent canine.

54.  After extraction of retained primary canine, permanent
canine was exposed and loop-button bonded.
 With canine positioned buccally and only vertical forces
needed, Kilroy II Spring was slid onto rectangular archwire
and ligated to loop-button. Favorable vertical eruption was
achieved in two months.

55.  Patient after 15 months of treatment.

56.  The Kilroy Spring is fabricated from 0.016 inch stainless
steel wire.
 Four helices are bent in the same plane to engage the main
archwire, and a central vertical loop ending in a helix is
extended perpendicularly

57.  18-year-old female with bilateral impacted upper
permanent canines and retained upper deciduous canines.

58.  placement and activation of modified Kilroy Springs after
surgical exposure of impacted canines.
 modified Kilroy I Spring that can be applied without removal of
the deciduous canine, thus improving the patient’s esthetic
appearance and helping to maintain the canine space.

59.  After 13 weeks of extrusion.
 After six months of extrusion, Kilroy springs removed, permanent
canines bracketed, and 0.016" copper nickel titanium wire placed in
upper arch.
 Rectangular archwire used for completion
of space closure with elastomeric chain

60.  Patient after 18 months of orthodontic treatment.

61.  A ballista loop is a simple, convenient, unobtrusive method
of applying a vertical force to a palatally impacted tooth to
erupt the crown into the center of the alveolus.
 0.018-inch continuous SS archwire used to form the
spring.

62.  19.3-year-old female.
 Panoramic radiograph and CBCT assessment reveal
bilateral maxillary canine impaction, with positioning
favorable to extrusion and placement within the dental arch.

63.  The patient was referred to a surgeon for extraction of the
primary canines, exposure, and placement of attachment
on the impacted canines to pull them directly down from
their current position.
Gold chain

64.  A ballista appliance ( 0.018-inch archwire ) was used to
prevent a facial pull of the canines in order to avoid and
prevent resorption of the roots of the lateral incisors.
 This type of orthodontic force will mimic the natural
eruption pathway.
 Once the tooth has been erupted, it can be bracketed so
that final movement and finishing can be accomplished.

65.  16-year-old girl with impacted maxillary right canine in
the mid-alveolar region, and the primary canine had not
exfoliated.
 After initial alignment of the maxillary teeth, the
maxillary primary canine was extracted, but the
permanent canine did not erupt.

66.  Labial and palatal flaps were reflected, bone was removed
to expose the incisal third of the permanent canine, and a
pin was placed into the canine crown.
 The flaps were repositioned, leaving the pin exposed in
the mid-crestal area.

67.  Two months later, a Ballista spring was created in the
maxillary archwire.
 The spring was activated to deliver a vertical extrusive
force to the canine.

68.  With this technique, the crown typically erupts into the
center of the alveolar ridge, similar to a naturally erupting
tooth.
 The post-treatment photograph shows that the gingival
levels of the right and left canines are identical.

69.  This technique consist of double wires (auxiliary and base
wire) , the auxiliary wire can be segmented or continuous.

70.  Piggyback technique uses to maintain the main archwire,
and tends to increase the stabilizing forces on the
abutment teeth and minimize the overall forces on these
teeth. Then use a lighter auxiliary piggyback wire to
provide inherent flexibility to correct the malposed tooth.

71.  Rigid stainless steel base archwires with significantly
higher elastic modulus, e.g. 0.018-inch or 0.019X0.025-
inch SSW, are preferred to limit unwanted effects on
anchor units and an auxiliary super elastic NiTi (including
thermal NiTi) archwire of 0.012- inch or 0.014-inch to
continue the eruptive process of tooth .

72.  Subsequent alignment using the piggyback technique by
ligating the tooth into the auxillary continuous archwire
while the ends of the wire inserted into the auxiliary tubes
of the bands .
 Once the crown has erupted far enough to accommodate a
bracket placement , the bracket then attached.

73.  Advantages :
 NiTi wires are considered ideal as they provide a
relatively constant, light force with high flexibility and
range allowing engagement of significantly displaced
teeth.

74.  The applied forces to the malposed tooth create undesired
tooth movements in the abutment teeth, a sequence of
wires is usually required to realign all of the teeth. The
Piggyback technique helps to avoid this waste of time and
resources.

75.  With single light arch wire the reciprocal forces will
adversely affect the other teeth in the arch, especially
those adjacent to the impacted one. This may create an
iatrogenic open bite, canted occlusal plane, crossbite, etc.

76.  The main disadvantage is increased friction due to the
doubled archwires.
 Moreover, the force level also requires careful
consideration as too much force may result in hyalinization
and, in some cases, may even prevent the desired tooth
movement.

77.  Overlay wire can be used with conventional brackets or
Self-litigating brackets with additional auxiliary slots
Forestadent BioQuick bracket with
auxiliary slot (dimension .016″ x
.016″).
Conventional bracket

78.  A 17-year-old female with an un-erupted upper left
canine.
 Clinical and radiographic examination : the upper left
canine was found to be overlying both the left lateral and
central incisors with a significant amount of root
resorption suspected .
 Retained upper left C.

79.  Cone Beam CT scan of the area showed revealed
extensive resorption to the upper left central incisor and
resorption to the upper left lateral incisor involving 50%
of the dentine but sparing the pulp.

80.  treatment plans :
 placement of the ectopic canine in the correct canine
position with the ultimate need for replacement of the
both central and lateral incisors.
 Alternatively the ectopic canine could be aligned in the
central incisor position accepting the replacement of
central and lateral incisors.

81.  The first option was preferred and arrangement to expose and
place a gold chain to the ectopic canine was undertaken.
 During the alignment phase it was clear that the ectopic canine
was developing towards the central incisor region and a
change in treatment plan was agreed, favoring the second
option.

82.  An upper fixed appliance was placed and progressed to
stainless steel archwires.

83.  Then the upper central incisor was extracted and the
remaining root removed .
 a bracket placed on the partially erupted canine to start
alignment.
 To maintain some form of aesthetics the central incisor
was modified and replaced back on the archwire.

84.  As the partially erupted canine continued to align, the
crown of the central incisor was gradually reduced to
provide vertical alignment space.
 The partially erupted canine has been fully engaged with
a Ni-Ti ‘piggy-back’.
 A stainless steel base arch-wire is used to support the
anchorage.

85.  Treatment was completed to the upper left canine , and
arrangement made to restore and camouflage the crown to
resemble the central incisor.

86.  The appearance of the canine in the central incisor
position with restorative modifications.
 upper left retained C will be left in situ until a
replacement is needed .