Traction of Impacted Maxillary Canine

SupervisionProf. Maher Fouda

Prepared by Mohammed Al-Awdi

ORTHODONTIC DEPARTMENT, MANSOURA UNIVERSITY, EGYPT

Introduction 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.

Introduction 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.

Introduction 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.

DIAGNOSIS OF CANINE IMPACTION1. 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 bulge2. Radiographic Diagnosis A) Periapical films B) Occlusal films C) CBCI

Etiology of canine impaction 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

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

Etiology of canine impaction Pathological lesions such as cysts Absence of maxillary lateral incisor Dilaceration of the root Heredity

THEORIES OF CANINE IMPACTION 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.

SURGICAL EXPOSURE Indicated when tooth does not erupt

spontaneously after creating space in the arch.

SURGICAL EXPOSURE

Two schools of thought exist : open or closed eruption technique.

Open eruption technique:# Excisional approach: Canine crown coronal to mucogingival junction.

gold chain

SURGICAL EXPOSURE Open eruption technique:# Apically positioned flap : Canine crown apical to mucogingival junction .

SURGICAL EXPOSURE 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.

SURGICAL EXPOSURE 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

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.

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.Ligature w

ire

SURGICAL EXPOSURE

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.

Biomechanical considerations of canine impaction

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.

Biomechanical considerations of canine impaction

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

Biomechanical considerations of canine impaction

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.

Biomechanical considerations of canine impaction

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.

For impacted canine traction the Following considerations are recommended:

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

For impacted canine traction the Following considerations are recommended:

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

For impacted canine traction the Following considerations are recommended:

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.

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

Case 1

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.

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.

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

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

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 .

Case 2

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

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

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

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.

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

Total treatment time was 15 months .

The Kilroy Spring 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.

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

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

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 .

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 .

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.

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

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 .

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

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.

Case 1

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.

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.

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.

Case 2

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.

After one month of rotation.

Bracket bonded to canine after four months of rotation.

Patient after 39 months of total active treatment.

Kilroy II Spring 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.

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

Case 1

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.

Patient after 15 months of treatment.

A Modified Kilroy Spring 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

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

Case 1

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.

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

Patient after 18 months of orthodontic treatment.

ballista spring 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.

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.

Case 1

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

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.

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.

Case 2

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.

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.

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.

Piggyback technique This technique consist of double wires

(auxiliary and base wire) , the auxiliary wire can be segmented or continuous.

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.

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 .

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.

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.

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.

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.

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.

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

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.

Case

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.

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.

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.

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

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.

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.

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

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 .