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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/284722889
Management of impacted canine
BOOK · JANUARY 2015
CITATION
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READS
17
3 AUTHORS, INCLUDING:
Ravi Shanthraj
JSS Dental College and Hospital
29 PUBLICATIONS 16 CITATIONS
SEE PROFILE
Available from: Pratik Patel
Retrieved on: 19 March 2016
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CONTENTS
1. INTRODUCTION 1
2. STAGES OF ERUPTION OF CANINES 3
3. PREVALENCE AND ETIOLOGY 12
4. SEQUELAE OF CANINE IMPACTION 21
5. DIAGNOSIS23
6. PROGNOSIS
7. PREVENTION OF MAXILLARY CANINE IMPACTION AND
TREATMENT ALTERNATIVES
8. WHEN TO EXTRACT
9. GENERAL PRINCIPLES OF MECHANOTHERAPY AND
PERIODONTAL CONSIDERATIONS
10. MANAGEMENT OF IMPACTED CANINES
11. METHODS OF APPLYING TRACTION
12. RETENTION CONSIDERATIONS
13. CONCLUSION
14. BIBLIOGRAPHY
3
3
4
4
4
6
8
8
8
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1
INTRODUCTION
The permanent canines are the foundation of an esthetic smile and functional
occlusion. Factors that interfere with its development and eruption had serious
consequences on esthetics, function and stability of stomatognathic system.
The orthodontic treatment of impacted maxillary canine remains a challenge to
today
exposure of the impacted tooth, followed by orthodontic traction to guide and align it
into the dental arch. Bone loss, root resorption, and gingival recession around the
treated teeth are some of the most common complications.
Early diagnosis and intervention could save the time, expense, and more complex
treatment in the permanent dentition. Tooth impaction can be defined as the
infraosseous position of the tooth after the expected time of eruption, whereas the
anomalous infraosseous position of the canine before the expected time of eruption
can be defined as a displacement. Most of the time, palatal displacement of the
maxillary canine results in impaction.1,2
Canines are considered the corner stones of the dental arch. Impacted canines are
those with a delayed eruption time or that are not expected to erupt completely based
on clinical and radiographic assessment.3,4,5 Abnormal eruption paths within the
dentoalveolar process may result in impactions and serious clinical ramifications.
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2
With early detection, timely interception and well-managed surgical and orthodontic
treatment, impacted maxillary canines can be allowed to erupt and be guided to an
appropriate location in the dental arch. However, it is only with interdisciplinary care
of general dentists and specialists that impacted maxillary canines can be treated
successfully.
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3
STAGES OF ERUPTION OF CANINES
The bony crypts of the canines are located near the external border of the nasal fossae
anterior to the sinuses, from which they are separated only by a thin lamina of bone
(Figs 1 and 2).6,7
Taken together, the maxillary teeth have a conical appearance. As a result, the bony
crypts of the canines, which are placed higher than the others, are the most internal.
Their buds develop behind the roots of the primary teeth and behind the buds of the
other permanent teeth.
In a view of a skeletal specimen of a 4-year-old child, the primary first molar, the bud
of the first premolar, and the bud of the permanent canine have the appearance of
three steps of an ascending stairway tipped toward the anteroexternal angle of the
opening of the nasal cavity ( Fig 1).
(arrows)
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4
Intraosseous Eruptive Pathways7
By the time children are 6 to 7 years old, calcification of canine crowns has been
completed and, as root formation proceeds along the nasal border in the crypt that
the crowns had occupied, the teeth are ready to begin erupting. They maintain their
spatial relationships with the nasal and antral cavities as well as with the other teeth
in the arch during calcification (Figs 3and 4). As they move along the lower third of
the lateral incisor roots, the canines erupt almost vertically within the dental arch,
usually with a mesial inclination of several degrees (Fig 5).
Still moving at the side of the lateral incisors, the canines continue their journey until
they reach the occlusal plane. After passing the centers of resistance of the lateral
incisors, the emerging canines begin to exert a mesial pressure on the lateral incisor
roots and then on their crowns, which straightens the anterior dentition. The long
axes of these teeth progressively lose their apical convergence as the midline
diastema completes its closure (Figs 6 and 7).
During the 3 or 4 years that precede the eruption of the maxillary canines, their
proper position can be confirmed by palpation.
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5
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6
In the middle period of the deciduous dentition, a periapical radiograph of the
premaxillary region will show the fully completed deciduous incisor roots. It will
show the overlapping shadows of the permanent central and lateral incisors, more or
less in the same horizontal plane as the apical half of the roots of the deciduous
incisors with the canines being sited higher up. The overlap of the permanent teeth
crowns is due to the fact that these relatively wide permanent teeth are all contained
in a narrow area and at this time, are initially located palatal in the alveolus. The
developmental position of the lateral incisors is palatal with relation to both the
central incisors and to the permanent canines. For these reasons, the periapical view
described above gives the appearance of severe crowding.
During the early eruptive movements of the central incisors, a progressive resorption
of the roots of the deciduous incisors occurs. The permanent incisors migrate slowly
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across from the palatal side of the arch to the labial, as they proceed in their
downward path, until the teeth erupt into a more labial perimeter than was defined by
the deciduous incisor teeth before their shedding. During this process, the wide
crown portion of the central incisors will have moved downwards and labially. As
this occurs, the progressively narrower CEJ area and then root portion of the central
incisor comes to lie mesial to the unerupted lateral incisor crowns. This leads to the
fairly rapid provision of space at this level in the alveolus. The lateral incisor
migrates labially into this area as it begins its downward eruption path. Additionally,
the downward eruption movement distances it from the permanent canine crown,
providing more space for it to move labially, following closely behind the central
incisor.
With the eruption of the central incisors, the lateral incisor crowns move from a
lingual relationship into a direct distal relationship with the central incisor roots,
initially at a higher level. As this occurs, the presence of the lateral incisor crowns
displaces the developing apical area of the central incisors towards one another, since
these are at the same level, within the alveolar bone. With the central incisor apices
held together in this way, the crowns of these teeth are flared distally. A
developmentally normal median diastema is thus produced, which has been termed
the
A year or so later, the lateral incisors will have descended along the distal side of the
central incisor roots, to release their hold on the narrowed inter-apical width of the
central incisor roots, allowing the roots to drift apart. The lateral incisors continue to
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move inferiorly along their eruptive path, progressively reducing their eruptive path,
progressively reducing their constricting influence on the central incisor roots until
they reach the distal side of the necks of the central incisor crowns. At this point,
their presence and continued downward migration serves to provide a mesially
directed force to crowns of these teeth, moving them towards one another and
partially closing off the median diastema. The long axes of the central incisor teeth
will also have changed, with the roots becoming more parallel. The lateral incisor
long axes, however, are relatively flared in the coronal direction, with their root
apices close to those of the central incisors.
A periapical view of the area at this time will show the unerupted permanent canine
crowns, of each side, pointing mesially towards the lateral incisor apical area. They
appear to be the containing influence that causes the apical convergence of the incisor
roots and the reason that the median diastema has not completely closed. Subsequent
follow-up radiographs of the area will show the permanent canine altering its
relationship as it moves downwards along the distal side of the root of the lateral
incisor, uprighting the long axis of that tooth. The canine
more vertical as it progresses and as the root of the deciduous canine becomes
resorbed. With the shedding of the deciduous canine, it finally erupts with a slight
mesial inclination, taking up its place in the arch by moving the crowns of the
incisors towards the midline, to close off the diastema completely. As all this occurs,
the long axes of the incisor teeth change from being apically convergent to become
more parallel and even slightly divergent.
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9
Throughout the period of its downward progress, the permanent canine is
conspicuously palpable on the buccal side of the alveolar ridge, from as early as 2-3
years prior to its normal eruption, which normally occurs at the age of 11-13 years.
Canines
Ectopic canines develop in:
a) the alveolus or
b) the hard palate
A)Alveolar process
To move an unerupted canine tooth that is stalled and not proceeding toward the
alveolar crest, the orthodontist must first bond an attachment to the tooth's crown
after uncovering it in either a palatal or a buccal approach, depending on its
relationship to the adjoining lateral incisor. The need to select a surgical pathway has
led practitioners to describe these teeth as being palatally or buccally impacted, a
qualification that has resulted in erroneous spatial conceptualizations and,
consequently, miscalculated eruptive paths (Korbendau and Pajoni 1999). While the
maxillary canine tooth always occupies a palatal position, it is possible for its crown
to move across the labial root surface of the lateral incisor and emerge into the arch
labially. But the osseous palatal wall and its fibromucosal covering always prevent a
dystopic lingual emergence (Fig 8).
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B)Hard palate6 ,7
The hard palate is an osseous plate lying perpendicular to the alveolar process that
separates the oral cavity from the nasal cavity. When a canine tooth in its bony crypt
is not oriented vertically toward the alveolar crest, it may develop within the spongy
palatal bone and begin to move horizontally.
The growing tooth, maintaining the orientation of the bud, may continue parallel to
the nasal wall toward the apices of the incisors (Figs 9 and 10). An errant canine
might equally stray from the median sagittal plane to encounter the premolar roots,
sometimes provoking them to resorb. Generally, canines that lie horizontally do not
have curved roots and will continue to develop within the confines of the hard palate
(Fig 11).
Canines may develop above the roots of maxillary teeth in the upper part of the hard
palate, where the space narrows progressively as it becomes more distant from the
floor of the nasal cavity. The triangular space, corresponding to the upper half of the
bony crypt, is bounded by the nasal cavities and the sinuses. Usually these teeth move
labially; other trajectories are rare (Fig 11).7
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12
PREVALENCE AND ETIOLOGY
I. Prevalence
Impaction is defined as the inability of the tooth to erupt in the oral cavity because of
some barrier or obstruction in its path (more specifically by a tooth or bone or soft
tissues).
A tooth is considered impacted when
which there is clinical or radiographic evidence that further eruption may not take
place.8
Any tooth may be impacted, but certain ones are more commonly affected than the
others. Thus, the maxillary and mandibular third molars and the maxillary cuspids are
the most frequently impacted teeth followed by premolars and supernumerary teeth
of the third molars, the mandibular teeth are more apt to exhibit severe impaction
than the maxillary teeth
A common guideline for diagnosis of impactions is given by Becker: the presence of
a tooth whose root is one-half to three-quarters developed whose unaided eruption is
unlikely to occur.9 Impaction of maxillary canines is a common finding. The canine
is the second most frequently impacted tooth3, after the third molar, and has an
incidence of approximately 1 to 3 percent in Caucasions.4-7 In the case of the
maxillary canine, more impactions are found in females than males and palatal
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impactions are twice or more as likely as buccal impactions in Caucasian
populations.10,11,12
Maxillary canines are the most commonly impacted teeth, second only to third
molars.2 Maxillary canine impaction occurs in approximately 2% of the population
and is twice as common in females as it is in males. The incidence of canine
impaction in the maxilla is more than twice that in the mandible. Of all patients who
have impacted maxillary canines, 8% have bilateral impactions.9 Approximately one-
third of impacted maxillary canines are located labially and two-thirds are located
palatally.13,14 Canine impaction can be caused by various factors. The exact etiology
of palatally displaced maxillary canines is unknown. The results of Jacoby15 study
showed that 85% of palatally impacted canines had sufficient space for eruption,
whereas only 17% of labially impacted canines had sufficient space. Therefore, arch
length discrepancy is thought to be a primary etiologic factor for labially impacted
canines.
Etiology
1. Inadequate space in the dental arch for eruption
The phylogenetic theory:
Due to evolution, the human jaw size is becoming smaller and since the third
molar tooth is last to erupt, there may not be room for it to emerge in oral cavity.
Mendelian theory:
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Here genetic variations play a major role. If the individual genetically receives
a small jaw from one of the parents and / or large teeth from the other parent,
then impacted teeth can be seen because of
The first comprehensive inquiry into malocclusion and its causes was by Weston
Price. In 1930 the world to document the nutritional habits and physical
degeneration of people living on contemporary
increase in malocclusion in societies living on contemporary diets of prepared foods.
The incidence of malocclusion amongst aboriginal people increased after contact
with commercial societies. He examined both living populations and many
collections of archeological material. This observation gives rise to a theory widely
favored among anthropologists which may be stated as follows:
Malocclusion arises from lack of chewing stress with the modern processed
diet. This disuse has reduced jaw growth and increased the incidence of occlusal
variation.
However the overall picture is not as simple as stated in the above sentence. It is a
combination of various factors.
FACTORS:
1. Hominid dental system is small relative to apes and has decreased in size over
evolutionary time
2. Potential effect of primitive food processing technology
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3. Increasing brain size reduces space available for oral features
4. The influence of language on the oral system
To summarize :
Humans do not have claws, razor-sharp teeth or the other adaptations found in
carnivores because from the very inception we have used technology at first in
the form of stone tools to serve the same functions as claws, sharp teeth etc.
This buffered humans from the pressures associated with the development of
features associated with carnivores.
Additional selection pressures on the human head came from encephalization,
bipedal posture and the development of language.
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GENETIC FACTORS
1. Heredity.
2. Malposed tooth germ.
3. Presence of an alveol
Two major theories associate
guidance theory and genetic t
erupts along the root of the lat
The etiology of canine i
presence of an abnormal o
dilacerated root, ankylosis, i
dental arches, failure to resor
r cleft.8
d with palatally displaced maxillary c
eory.16
The guidance theory proposes t
ral incisor.
pactions can occasionally be directly a
r pathological condition such as: ne
trogenic or systemic conditions.11
Cr
b or exfoliate primary canines, and ea
17
nines are the
hat the canine
tributed to the
oplasm, cyst,
wding of the
ly loss of the
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primary canine have also been identified as possible risk factors for impaction,17 but
fail to explain a large percentage of cases.18,19 More frequently, it is impossible to
identify a definitive cause for the impaction. Several theories have been advanced to
explain canine impactions in the absence of an obvious etiology. The developmental
process of the canine is relatively long, both in temporal duration and in its path of
eruption.
Becker, & others20,21 have advanced the guidance theory of eruption which
states that the maxillary canine is guided into position by the distal surface of the
lateral incisor root. Deviations from the prototypical model, including the absence,
aberrant morphology, or mistiming of the development of the lateral incisor are
implicated as factors in the impaction of maxillary canines.
In the absence of a conclusive understanding of its etiology, it is assumed that the
cause of an individual impaction may be related to one or more of the above theories,
or of idiopathic origin.
Complications can arise in the treatment of impacted canines. The most common of
these is resorption of incisor roots. Incidence of lateral incisor resorption has been
reported in CT studies at 27,38,and 67 percent, with resorption of the central incisor
at 9, 11 and 23 percent. Improper orthodontic mechanics may also result in iatrogenic
damage to the incisors. In either case, devitalization of adjacent teeth is a possibility.
Ankylosis of the impacted canine is an uncommon finding, occurring in only 1
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percent of cases. Failure in the alignment of impacted canines can also occur, more
frequently in adults.22-26
According to Thilander & Myrberg, 1943 cumulative prevalence of canine impaction
in 7-13 yr old children is 2.2% . However Dachi and Howell, 1961 incidence of
maxillary canine impaction is 0.92% and 1.7% . According to Ericson & Kurol, 1986
incidence of mandibular canine impaction 0.35%. of all patients with maxillary
impacted canines 8% have bilateral impaction.
Palatal vs Labial impaction
It is estimated that the incidence of palatal impaction exceeds that of labial
impaction by a ratio of at least 2:1 or 3:1.
Ectopic labially positioned canines may erupt on their own without surgical
exposure and orthodontic treatment, frequently high in the sulcus or alveolar ridge.
On the other hand, palatally impacted canines seldom erupt without intervention. It is
believed that this impeded eruption is due to the thickness of the palatal cortical bone,
as well as the dense, thick and resistant palatal mucosa.
Palatally impacted canines are more often inclined in a horizontal/oblique
direction, where as labial impactions offer a more favorable vertical angulations. Yet
they are still considered difficult because of the needed delicacy in managing the
associated hard and soft tissues.
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20
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SEQUELAE OF CANINE IMPACTION
Shafer et al.27 suggested the following sequelae for canine impaction:
1. Labial or lingual malpositioning of the impacted tooth,
2. Migration of the neighboring teeth and loss of arch length,
3. Internal resorption,
4. Dentigerous cyst formation,
5. External root resorption of the impacted tooth, as well as the neighboring teeth,
6. Infection particularly with partial eruption,
7. Referred pain
8. Combinations of the above sequelae.
It is estimated that in 0.71% of children in the 10 13 year age group, permanent
incisors have resorbed because of the ectopic eruption of maxillary canines.28 On the
other hand, the presence of the impacted canine may cause no untoward effects
during the lifetime of the person. These potential complications, as well as others that
will be detailed later, emphasize the need for close observation of the development
and eruption of these teeth during
growing child.
The normal sized and early developing lateral incisor root obstructs the deviated
eruption path of canine and consequently stands a considerably greater chance of
being damaged by resorption. Whereas the anomalous lateral incisors (peg shaped &
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or small mesiodistal crown width) their small and late developing roots are more
easily bypassed and not endangered by the impacted tooth.
Normal Sized Lt. Incisor Early Dev.
Root
Chance of
Resorption
Anomalous Lt. Incisor (Peg
or small Md crown width)
Small Late
Dev. Root
Chance of
Resorption
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DIAGNOSIS
The identification of an impacted canine is only the first step in the proper
diagnosis of such a case. After examining complicating factors such as pathologic
findings and possible root resorption of adjacent teeth, the orthodontist
quickly turns to the localization of the impacted tooth. Visualization of the correct
location and orientation is essential for determining the proper course of treatment,
which may consist of observation, extraction, or attempted alignment of the impacted
tooth in conjunction with limited or comprehensive orthodontics. An appreciation for
location of the impacted tooth becomes essential in determining appropriate surgical
strategies as well as the feasibility and mechanotherapy of orthodontic alignment.
The proper localization of the impacted tooth plays a crucial role in determining the
feasibility as well as the proper access for the surgical approach and the proper
direction for the application of orthodontic force
A. Clinical Evaluation
It has been suggested that the following clinical signs might be indicative of canine
impaction9
Clinical signs:
1. Delayed eruption of the permanent canine or prolonged retention of the
deciduous canine beyond 14 15 years of age,
2. Absence of a normal labial canine bulge,
3. Presence of a palatal bulge,
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4. Delayed eruption, distal tipping, or migration (splaying) of the lateral
incisor.
According to Ericson and Kurol,28 the absence of the
should not be considered as indicative of canine impaction. In their evaluation of 505
school children between 10 and 12 years of age, they found that 29% of the children
had non-palpable canines at 10 years, but only 5% had it at 11 years, whereas at later
ages only 3% had nonpalpable canines. Therefore, for an accurate diagnosis, the
clinical examination should be supplemented with a radiographic evaluation.
B. Radiographic Evaluation
Traditional Localization Methods
Although various radiographic exposures including occlusal films, panoramic views,
and lateral cephalograms can help in evaluating the position of the canines, in most
cases, periapical films are uniquely reliable for that purpose.9,11
Periapical films
A single periapical film provides the clinician with a two-dimensional representation
of the dentition. In other words, it would relate the canine to the neighboring teeth
both mesiodistally and superoinferiorly. To evaluate the position of the canine
buccolingually, a second periapical film should be obtained by one of the following
methods.
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Tube-shift technique or Clark
Early methods for localization of impacted maxillary canines involved the use of
intraoral radiographs. A simple but useful method was proposed by Clark 29 and is
now referred to as the tube-shift or parallax method and utilizes the so-called buccal
object rule.
Two periapical films are taken of the same area, with the horizontal angulation of the
cone changed when the second film is taken. If the object in question moves in the
same direction as the cone, it is lingually positioned. If the object moves in the
opposite direction, it is situated closer to the source of radiation and is therefore
buccally located.
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Buccal-object rule : If the vertical angulation of the cone is changed by
approximately 20
the direction opposite to the source of radiation. On the other hand, the lingual object
will move in the same direction as the source of radiation. The basic principle of this
technique deals with the foreshortening and elongation of the images of the films.
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Occlusal films24
Another useful intraoral radiograph is the maxillary occlusal film. The anterior
occlusal is taken at an angle of 60 degrees to the occlusal plane, is simpler to
execute and provides a lower radiographic dose than the vertex occlusal, which is
taken at 110 degrees to the occlusal plane, parallel to the long axis of the central
incisors. Either film allows the clinician to simultaneously visualize the impacted
tooth in the anteroposterior and transverse planes of space
It also helps to determine the buccolingual position of the impacted canine in
conjunction with the periapical films, provided that the image of the impacted canine
is not superimposed on the other teeth.
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Extraoral Radiographs 24,25,26
In addition to intraoral films, cephalograms and panoramic radiographs have also
been used to localize impacted teeth. In the case of the cephalogram, it is important to
note that both the lateral and posteroanterior (PA) cephalogram can be used to
discern the position of the impaction.
Frontal and lateral cephalograms
These can sometimes aid in the determination of the position of the impacted canine,
particularly its relationship to other facial structures (e.g., the maxillary sinus and the
floor of the nose).
The lateral view can provide information about the anteroposterior position of the
canine, the vertical position, and the angulation in the sagittal plane. The PA
cephalogram can clarify the transverse position of the canine and its angulation in the
frontal plane. In theory, by using both lateral and PA cephalograms one should be
able to determine a fairly accurate three dimensional location of the impacted tooth.
Weaknesses of this method include the presence of anatomical structures that
interfere with the projection of the canine and in the case of the lateral cephalogram,
the lack of resolution between left and right sides.
Panoramic films
These are also used to localize impacted teeth in all three planes of space, as much
the same as with two periapical films in the tube-shift method, with the understanding
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29
that the source of radiation comes from behind the patient; thus, the movements are
reversed for position.
Since the development of the panoramic radiograph, practitioners have relied heavily
on this method for the localization of impacted canines.26,30
The vertical position of
the canine is readily assessed, as is basic information regarding the location of the
cuspid in relation to the roots of the adjacent teeth.
The palatal versus labial determination can be attempted based on the magnification
of the impacted tooth on the panoramic film.31,32
Palatally impacted canines are
located further from the film or sensor than the other the teeth in the arch, so they
appear magnified relative to their expected size. By contrast, a canine located labial
to the arch will appear reduced in size compared to the adjacent teeth. In one study
utilizing two radiologists, this determination was made correctly 89 percent of the
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time using a panoramic radiograph only.31
In another study also using only panoramic
radiographs, researchers were able to accurately predict the position of palatally
displaced crowns 80 percent of the time.33
Chaushu et al34
found a similar success
rate of 88 percent. In addition, when their sample was restricted to canines whose
crown overlapped the middle or coronal third of the adjacent teeth (eliminating those
found in apical areas), the rate of successful localization increased to 100 percent.
One of the most widely used methods for objectively describing the location and
angulation of an impacted canine as viewed on a panoramic radiograph was
developed by Ericson and Kurol.8
Two angular measurements were measured,
relating the long axis of the canine to the vertical midline and the long axis of the
lateral incisor. A linear measurement was made from the cusp tip to the occlusal
plane at a 90 degree angle, and the anteroposterior position of the cusp tip was
assessed and assigned to one of five zones.
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31
The method of objectively classifying canines by their appearance on
panoramic radiographs has been used in attempts to predict root resorption, treatment
success, periodontal outcomes and treatment duration.35-39
CT Scanning
Recently, the use of computed tomography (CT) scanning has been suggested), to
identify the exact position of an impacted canine especially when root resorption of
lateral incisor is suspected.
CT scanning is a method in which clear serial radiographs may be taken at gradated
depths in any part of the human body.
Advantages of CT Scanning Include
Technique allows for elimination of the super imposition of other structures that
will obscure the image of the object that we attempt to view in traditional
radiography.
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By viewing serial radiographic `Slices' of the maxilla, the relationship of the
impacted tooth to the adjacent teeth, in all three planes of space, may be accurately
assessed
The method may also give accurate information regarding early root resorption
particularly of the buccal and palatal surfaces. This may not be possible to diagnose
by any other method, prior to treatment.
CT/CBCT
One method for obtaining more accurate images of hard tissues, including the
dentition, is computed tomography (CT). This technology exists in several forms,
including traditional medical CT, which utilizes fan shaped beams to capture axial
slices that are reconstructed by a computer before viewing. More recently, cone
shaped beams have been used in the creation of cone beam computed tomography
(CBCT) images at a much lower radiation dose to the patient.40 Both technologies
produce a similar three dimensional volume41, which can be manipulated to provide a
number of two and three dimensional views, free of many of the distortions inherent
in traditional radiographic imaging. In addition, the use of orthogonal beam
projection and computer reconstruction yields a volume that has no magnification
error and provides true linear and angular measurements.42
This technology has been applied to the management of the impacted maxillary
canine. Several studies have successfully used CT technology to provide descriptive
commentary on the position of impacted canines.43-48 The most useful feature of
CBCT technology in the diagnosis of impactions is the elimination of artifacts such
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as blurring and the overlapping of adjacent teeth.47 In addition, use of the CT volume
provided superior information on the relationship of the canine to the adjacent roots
and allowed more accurate assessment of root resorption than afforded by traditional
radiographs.45,48
Clinicians can localize canines by using advanced three dimensional imaging
techniques. Cone beam computed tomography (CBCT) can identify and locate the
position of impacted canines accurately. By using this imaging technique, dentists
also can assess any damage to the roots of adjacent teeth and the amount of bone
surrounding each tooth. However, increased cost, time, radiation exposure, and
medicolegal issues associated with using CBCT limit its routine use. The proper
localization of the impacted tooth plays a crucial role in determining the feasibility of
as well as the proper access for the surgical approach and the proper direction for the
application of orthodontic forces.
Several studies have used CBCT data to objectively measure the three dimensional
position of impacted maxillary canines. Walker et al created reference lines in
relation to anatomic landmarks to describe the position and angulations of the
impacted tooth. Liu et al performed a similar analysis on a large sample of 210
impacted maxillary canines and quantitatively described the canine position and the
presence of root resorption on adjacent teeth. Kau et al49 used constructed panoramic
and axial views generated from the CBCT volume to establish a scale of difficulty
designed to assess the probability of successful treatment.
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In comparison to traditional radiographs, the use of CBCT imaging represents a
significant advance in the state of the art. CBCT images have been shown to be of
superior quality in assessing crown and root shape, crown/root relationship, and
orientation than traditional two dimensional radiographs.50
The addition of CBCT to
the diagnostic armamentarium of the clinician has also been shown to affect
diagnosis and treatment planning decisions.42
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PROGNOSIS
Deep infraosseous location of the impacted canine can be assessed on the panoramic
image by using the modified version of the criterion proposed by Ericson & Kurol.
The tracing is made on panoramic radiographs.
The following lines are drawn and measurements made
The midline.
The occlusal plane (from the first molar to the incisal edge of the central incisor)
The long axes of the central incisor, of the lateral incisor , of the first bicuspid
and of the impacted canine.
The angle between the long axis of the impacted canine and the midline().
The distance between the cusp of the impacted canine and the occlusal plane.
The criteria to evaluate the position of the impacted canine:
1. The most medial position of the crown is identified and the severity of the
overlap assessed. Canines placed mesial to lateral incisor, distal to premolar,
success rate is less.
2. The inclination or angulation of the long axis of the canine is measured in
relation to the midline (Angulation greater than 40o shows poor prognosis)
3. The vertical height measured in millimeters from the canine tip to the occlusal
plane d >15mm again reveals poor prognosis.
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.
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PREVENTION OF MAXILLARY CANINE IMPACTION
AND TREATMENT ALTERNATIVES
When the clinician detects early signs of ectopic eruption of the canines, an attempt
should be made to prevent their impaction and its potential sequelae. Selective
extraction of the deciduous canines as early as 8 or 9 years of age has been suggested
by Williams55 as an interceptive approach to canine impaction in Class I uncrowded
cases.
Ericson and Kurol28 suggested that removal of the deciduous canine before the age of
11 years will normalize the position of the ectopically erupting permanent canines in
91% of the cases if the canine crown is distal to the midline of the lateral incisor. On
the other hand, the success rate is only 64% if the canine crown is mesial to the
midline of the lateral incisor.
TREATMENT ALTERNATIVES
Each patient with an impacted canine must undergo a comprehensive evaluation of
the malocclusion. The clinician should then consider the various treatment options
available for the patient, including the following:
a) No treatment if the patient does not desire it. In such a case, the clinician
should periodically evaluate the impacted tooth for any pathologic changes. It
should be remembered that the long term prognosis for retaining the deciduous
canine is poor, regardless of its present root length and the esthetic
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acceptability of its crown. This is because, in most cases, the root will
eventually resorb and the deciduous canine will have to be extracted.
b) Auto transplantation of the canine.
c) Extraction of the impacted canine and movement of a first premolar in its
position.
d) Extraction of the canine and posterior segmental osteotomy to move the buccal
segment mesially to close the residual space, which is a tedious surgical
procedure.
e) Prosthetic replacement of the canine, not amenable for juvenile patients.
f) Transalveolar transplantation of maxillary canines was reported by Soren
Sagne et al.as an alternative to orthodontic treatment of impacted maxillary
canines in adult patients. But, during this procedure it is important to minimize
trauma to the tooth, remove great amount of bone, leave the tooth in its
original position as long as possible and prepare a large socket for the tooth. It
is thus essential to avoid trauma from the bur to the cementum and
periodontium to loosen the tooth gently from its impacted positions and not to
force it into its new site with hard bone contact. Neglect of any of these
details, in the operative technique may cause resorption.51
g) Surgical exposure of the canine and orthodontic treatment to bring the tooth
into the line of occlusion. This is obviously the most desirable approach.
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WHEN TO EXTRACT
It should be emphasized that extraction of the labially erupting and crowded canine,
unsightly as this tooth may look, is contraindicated. Such an extraction might
temporarily improve the esthetics, but may complicate and compromise the
orthodontic treatment results, including the ability to provide the patient with a
functional occlusion.9 The extraction of the canine, although seldom considered,
might be a workable option in the following situations:
1) If it is ankylosed and cannot be transplanted.
2) If it is undergoing external or internal root resorption.
3) If its root is severely dilacerated.
4) If the impaction is severe on central lateral incisors and orthodontic movement
will jeopardize these teeth.
5) If the occlusion is acceptable, with the first premolar in the position of the canine
and with an otherwise functional occlusion with well-aligned teeth.
6) If there are pathologic changes (e.g. cystic formation, infection).
7) If the patient does not desire orthodontic treatment.
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GENERAL PRINCIPLES OF MECHANO-THERAPY AND
PERIODONTAL CONSIDERATIONS
The principles of orthodontic machano-therapy are presented as follows:
1. The appliance should have the capability to level and rotate all the teeth in same
jaw rapidly, and with controlled crown and root movements, to open adequate
space to accommodate the impacted tooth. This stage requires the use of fine
leveling and aligning archwires.
2. With the initial alignment achieved and no further movement of individual
erupted teeth needed, these teeth are transformed into a composite and rigid
anchorage unit, this is done by substituting the flexible archwires with a heavier
wire.
3. The surgical exposure of the crown of the impacted tooth should be performed in
a manner that will achieve a good periodontal prognosis of the treated result. An
attachment is bonded to it and the flap fully closed, with only a fine ligature wire
leading through the gingival tissue to the re-covered tooth.
4. Using an auxiliary means of traction from the now rigid orthodontic appliance, a
gentle and continuous light force, with a wide range of activity, is applied to the
tooth, and is aimed at erupting the impacted tooth.
5. There should be final detailing of the position of the formerly impacted tooth.
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Periodontal Considerations
Earlier methods of uncovering impacted canines advocated radical bone removal to
expose the crown of the impacted tooth so as to remove all bony obstacles and to
provide an easier path for tooth movement.
Kohavi et al. compared the periodontal health of canines exposed by such a "Radical"
exposure with those exposed by a more conservative "Light" exposure. In the latter
group, the exposed area was kept coronal to the cemento - enamel junction (CEJ).
Comparisons between the two groups indicated the absence of significant differences in
the plaque index, the gingival index, pocket depth or attached gingivae after treatment.
However, there were significant difference in bone supports i.e alveolar bone support in
the heavy exposure group was reduced.
It was concluded that exposure of the CEJ was a critical variable and should be avoided
as an objective during surgery.
Kohavi et al suggested that light movements like tipping cause significantly less bone
loss than heavy movements (Eg torque) during the traction of the impacted tooth.52
It can therefore be concluded that the combined effects of light surgical exposure and
light orthodontic movements and forces, are beneficial to the future periodontal health
of the tooth since they minimize the loss of alveolar bone support and potential injury to
the tooth during traction.
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It should be reemphasized that in surgical exposure of an impacted tooth, only enough
bone should be removed for the bracket placement and the CEJ should not intentionally
exposed.
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MANAGEMENT OF IMPACTED CANINES
The most desirable approach for managing impacted maxillary canines is early
diagnosis and interception of potential impaction.
A surgical exposure of the impacted tooth is indicated when the tooth does not erupt
spontaneously after creating enough space in the arch and should be attempted six
months after the completion of root formation. The flap designs for surgical exposure
should preserve the band of the attached gingiva and should guide the tooth to erupt
through its natural path of eruption.57
I. Management of the Palatally Impacted Canine
The most common methods used to bring palatally impacted canines into
occlusion are surgically exposing the teeth and allowing them to erupt naturally
during early or late mixed dentition and surgically exposing the teeth and placing a
bonded attachment to and using orthodontic forces to move the tooth.14 Kokich55
reported three methods for uncovering a labially impacted maxillary canine:
gingivectomy, creating an apically positioned flap, and using closed eruption
techniques .
Orthodontists have recommended that other clinicians first create adequate space in
the dental arch to accommodate the impacted canine and then surgically expose the
tooth to give them access so that they can apply mechanical force to erupt the tooth.
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Although various methods work, an efficient way to make impacted canines erupt is
to use closed-coil springs with eyelets, as long as no obstacles impede the path of the
canine. If the canine is in close proximity to the incisor roots and a buccally directed
force is applied, it will contact the roots and may cause damage. In addition, the
canine position may not improve due to the root obstacle.
Consequently, various techniques have been proposed that involve moving the
impacted tooth in an occlusal and posterior direction first and then moving it buccally
into the desired position. When using a bonded attachment and orthodontic forces to
bring the impacted canines into occlusion, it is important to remember that first
premolars should not be extracted until a successful attempt is made to move the
canines. If the attempt is unsuccessful, the permanent canines should be extracted.54
Various techniques are:
a) Surgical exposure, allowing natural eruption,
b) Surgical exposure with placement of an auxiliary attachment. Orthodontic
forces are subsequently applied to the attachment to move the impacted tooth.
a) Surgical exposure to allow natural eruption to occur:
This method is most useful when the canine has a correct axial inclination and does
not need to uprighted during its eruption. The progress of canine eruption, should be
monitored with roentgenograms with the use of reference points such as adjacent
tooth or the archwire. Clark recommended that a polycarbonate crown be placed over
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the impacted tooth after its surgical exposure. The crown should be made long
enough to extend through a window cut in the palatal tissue. The crown is then
cemented with a surgical paste or regular cement. Often 6 months to 1 year may
elapse before the impacted tooth has erupted sufficiently to permit removal of the
polycarbonate crown and its replacement with an orthodontic attachment. If the tooth
fails to erupt. Clark recommends the removal of any cicatricial tissue surrounding
the crown.
The main disadvantages of this approach are the spontaneous but slow canine
eruption, the increased treatment time, and the inability to influence the path of
eruption of the impacted canine.
b) Surgical exposure with the placement of an auxiliary:
After the surgical exposure of the impacted tooth, an auxiliary is attached to the
crown. Such an auxiliary can be either directly bonded to enamel or indirectly
attached to a cemented band or crown.
Approaches:
Two approaches are generally recommended with regard to the timing of placing the
attachment.
1. Lewis preferred a two-step approach:
First the canine is surgically uncovered and the area is packed with a surgical
dressing to avoid the filling in of tissues around the tooth. After wound healing,
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within 3 to 8 weeks, the pack is removed, and an attachment is placed on the
impacted tooth.
2. The second method is a one-step approach:
The attachment is placed on the tooth at the time of surgical exposure. The
tissues over the attachment should be excised, and a periodontal pack should be
placed. The pack will minimize patient discomfort and prevent the granulation
tissues from covering the attachment before the clinician is ready to apply
traction forces to the impacted tooth. This approach is particularly
recommended for palatally impacted teeth. One of the important advantages of
such an approach is that when the force is applied to the impacted tooth, the
clinician is able to visualize the crown of the tooth and to have better control
over the direction of tooth movement. This will avoid moving the impacted
tooth into the roots of the neighbouring teeth.
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II. Management Of Labially Impacted Canine
Management of labially impacted canines involves a stepwise procedure as follows:
a. Surgical exposure.
b. Placement of orthodontic attachment.
c. Traction force application.
Labial impaction of the maxillary canine is less frequent than palatal impaction
and is often caused by insufficient arch length. As a result, the canine is often
positioned high in the alveolar bone and erupts through the alveolar bone and
erupts through the alveolar mucosa. Fournier et al suggested that labially impacted
teeth with a favourable vertical position might be treated initially by surgical
exposure but without application of traction force. In younger patients the tooth
erupt on its own after surgical exposure but without application of traction force,
whereas in older patients traction is almost always indicated.55
Surgical Exposure
The absence of an adequate band of attached gingiva around the erupting canine may
cause inflammation of the periodontium. Vanarsdall and Corn emphasized the danger
to move teeth in presence of inflammation. Tissue resistance to the stress of
mastication and function is less than optimal and loss of periodontal support is
possible if precautions are not taken to alleviate such potential problems.53
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Therefore, it is recommended that surgical procedures designed to expose impacted
canine
attached gingival to the exposed tooth. Otherwise, improper softtissue management
may lead to mucogingival recession and loss of alveolar bone.
Before a labially impacted canine is exposed, careful consideration should be given
to creation of sufficient space to allow for the canine to be positioned in the area.
Usually if the tooth is impacted in the center of the alveolus a closed eruption
technique is indicated because an excisional approach and an apically positioned flap
are generally more difficult to perform, as extensive bone might need to be removed
from the labial surface of the crown. If the canine crown is positioned coronal to the
mucogingival junction an excisional approach will be appropriate. If the crown is
positioned apical to the mucogingival junction an excisional technique will be
inappropriate, as it will result in lack of attached gingiva after eruption of the tooth.
In this case an apically positioned flap is indicated.58 In Closed eruption technique the
flap is elevated and an attachment is placed on the impacted tooth. A ligature wire or
chain is placed over the attachment to activate after a week. The raised flap is
repositioned in its original location to permit eruption of the impacted canine in the
normal direction.......
If the crown is positioned significantly apical to the muco gingival junction an
apically positioned flap will also be inappropriate, because it will result in the
impossible re-intrusion of the tooth after orthodontic alignment. The re-intrusion of
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the tooth is due to the apical pull from the mucosa that has migrated coronally during
orthodontic eruption of the tooth.59,60........
The excisional technique must be performed only when sufficient gingiva is present,
to provide at least 2 to 3 mm of attached gingiva over the canine crown after it has
erupted. If the crown is positioned mesially and over the root of the lateral incisor,
the crown should be exposed completely with an apically positioned flap.58
After surgical exposure of the canine an attachment is bonded to the canine.
Vanarsdall and Corn recommend placement of a surgical dressing to protect the
tissues for seven to ten days if bleeding makes bonding of an attachment difficult or a
moisture insensitive primer can be used for bonding. 53 After removal of the dressing,
a direct bonded attachment can be placed in a dry field and tooth movement can then
be initiated. The use of a ligature wire to facilitate traction is reliable rather than
engaging a full arch wire.
Techniques Practiced To Uncover Labially Impacted Canine:
a) Excisional gingivectomy
b) Apically positioned flap
c) Closed eruption technique
The esthetic and functional outcomes of these procedures, such as gingival height,
clinical crown length, width of attached gingival, gingival scarring, relapse potential
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and attachment levels need to be critically assessed in order to identify the optional
method of uncovering labial impactions.
a) Excisional gingivectomy:
Pioneer method of uncovering impacted canines, advocated radical bone removal to
expose the crown of the impacted tooth so as to remove all bony obstacles and to
provide an easier path for tooth movement.
When there is little or no bone covering the crown of a labially impacted canine,
hence, an excision uncovering or an apically positioned flap or a closed eruption
technique could be used.58
Disadvantages:
The procedure is not functionally and esthetically suitable, as they bring about
increased loss of attached gingival & cause excessive gingival recession which is
functionally and aesthetically unacceptable.
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b) Apically Postioned Flap
Sufficient space is created to allow for the canine to be positioned in the arch. The
created space will provide an adequate zone of attached gingival that can act as a
donor site for the partial thickness apically or laterally repositioned flap.
Vanarsdall and Corn emphasized that the flap containing the keratinized tissue should
be placed to cover the CEJ and 2 to 3 mm of the crown.54
Advantages:
a. The new gingival attachment prevents marginal bone loss and gingival
recession that is frequently encountered with surgical exposure of impacted
teeth.
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b. The APF allows for greater movement of the marginal tissue. This would
minimize tension on the gingival tissues.
c. The procedure is indicated even in teeth located beyond the vestibular depth or
mucobuccal fold.
The apically positioned flap is a split thickness pedicle reflected from the edentulous
area. The incisions extend vertically into the vestibule and split thickness flap is
reflected. Bone covering the enamel is removed. Two thirds of the crown exposed,
and the connective tissue follicle, curetted from the periphery of the exposed portion
of the crown. The flap is then sutured to the periosteum, leaving one half to two
thirds of the crown uncovered. A surgical dressing is placed on the enamel to prevent
overgrowth of the adjacent tissue. The dressing is removed 1 week, post operatively
and the attachment placed on the uncovered tooth.
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III. CLOSED ERUPTION TECHNIQUE
This is the best method of uncovering labially impacted teeth. It involves elevating a
flap, placing an attachment on the impacted tooth returning the flap to its original
location. If the tooth is displaced near the nasal spine, pedicle flap is reflected.
Orthodontic attachment placed and the flap is returned to its original position for
complete closure. The orthodontic traction force is applied 1 week after creating a
normal direction of tooth eruption.
Further, the excision gingivectomy and apical positioned flap have more unesthetic
sequelae than those uncovered with closed eruption technique. Negative esthetic
effects, such as increased clinical crown length, decreased width of attached gingival,
gingival scaring and intrusive relapse are evident.
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METHODS OF ORTHODONTIC ATTACHMENT
Different methods of attachment to the impacted tooth have been suggested.
Earlier polycarbonate or gold crowns were cemented into the exposed crowns of
impacted teeth.
1. Wire lasso: The use of circumferential dead soft, ligature wire (Lasso) as an
attachment has been fairly common. This method is not recommended, as too
much of bone has to be removed so that the wire can be placed around the tooth
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circumference. Further, increased incidence of ankylosis, external root resorption
has been noted.
Fig 42 Lasso Wire
2. Some other technique like drilling holes at canine tip and passing ligature through
the hole and with the help of this traction force is applied.
3. Elastic ties and modules
Fig 43 Elastic ties
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4. Best method of orthodontic attachment is bondable mesh, bracket or lingual
button with ligature chain or gold chain to the bonded attachment. Furthermore,
this has conservative approach on the surgical exposure.
5. Multiple eyelet chain
6. Magnets (In Attractive Mode)
Removable versus fixed appliances
The use of fixed appliance to move the exposed tooth is advocated in most cases.
This is because there are certain disadvantages to the use of removable appliance,
including the need for patient co-operation, limited control of tooth movement and
the inability to treat complex malocclusion.
McDonald et al., and Fournier et al., suggested the use of Hawley type appliances
designed to transfer anchorage demands to the palatal vault and the alveolar ridge.
Such appliances might be useful in patients with multiple teeth missing when the use
of fixed appliances is not recommended. 61
One Arch Versus Two - Arch Treatment
Most malocclusions, including those that involve impacted canines, require placement
of the orthodontic appliance on both maxillary and mandibular arches.Such an
appliance will enable the orthodontist to achieve the desired biomechanical control
needed to obtain optimal results.
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The mandibular arch is not frequency used as a source of anchorage to move the
impacted maxillary canine.
This is due to the difficulty encountered in controlling the magnitude and direction of
the applied force from the mobile mandible. Therefore such inter arch mechanics
should be considered only when the desired forces cannot be applied from within the
maxillary arch.
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METHODS OF APPLYING TRACTION
Various methods have been used for moving the canine into proper alignment, these
include the use of light wire springs soldered to a heavy labial or palatal base wire,
mousetrap loops bent in the archwire and rubber bands. But with the introduction of
new orthodontic materials such as elastic threads and elastomeric chains, the
orthodontist has greater control of force magnitude and direction.
Regardless of the material used, the direction of the applied force should initially
move the impacted tooth away from the roots of the neighbouring teeth. In addition,
the following considerations are recommended.
a) The use of light forces to move the impacted tooth, no more than 2 ounces (60
grams) of force.62
b) Either availability or creation of sufficient space in the arch for the impacted
tooth.
c) Maintenance of the space by either continuous tying of the teeth mesial and
distal of the canine or placement of a passive open coiled spring on the arch
wire.
d) Provision by the arch wire of sufficient stiffness (e.g. 0.018 x 0.022 inch) to
resist deformation by the forces applied to its as the canine is extruded. The
added stiffness will minimize the undesirable roller-coaster effect caused by
intrusion of the anchor teeth as a reaction to the deflection of a lighter and hence
more flexible arch wire.
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EXTRUSION OF IMPACTED CUSPIDS
To extrude palatally impacted cuspids into a more favourable position before moving
them labially for incorporation into the arch.
MATERIALS
Kobayashi hook
Split rectangular extra oral hook
Specially bent 0.018
The wire should have 2 helices, perpendicular to each other and about 1/8
mesial and distal legs should extend about 1
Ligate the Kobayashi hook to the cuspid bracket before bonding the bracket and the
exposed cuspid. Place a rectangular stabilizing wire in the arch. Crimp the extra oral
hook, angulated labially and gingivally onto the rectangular stablising arch wire
opposite to the cuspid to be extruded.
Place the distal helix of the 0.018 rotated towards the occlusal surface over the
extra oral hook. Ligate the distal leg of the wire to the brackets over the stabilising
arch wire. Adjust the mesial leg to produce the desired amount and direction of
extrusion force. Ligate the mesial leg to the K hook with round elastic.
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The Monkey Hook 62
The Monkey Hook is a simple auxiliary with an open loop on each end for the
attachment of intraoral elastics or elastomeric chain, or for connecting to a bondable
loop-button. Its S-shaped design was inspired by the children
Monkeys
chain. The hook can be closed with a plier to prevent disengagement
Fig 44 Monkey Hook
Vertical Intermaxillary Eruptive Forces
The loop should be positioned parallel to the roots of the adjacent teeth to allow
subsequent attachment of more hooks for production of a variety of forces . If the
tooth is deeply impacted, a second Monkey Hook can be linked to the first.
Conventional intra-arch mechanics used to direct the eruption of impacted teeth, such
as elastic thread applied to a gold chain, use reciprocal forces that tend to tip or
intrude the teeth adjacent to the impacted tooth, thereby altering the occlusal plane. In
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contrast, Monkey Hooks can be attached to intermaxillary elastics, with anchorage
derived from the opposing dental arch.
Vertical Intra-Arch Eruptive Forces
If anchorage is unavailable from the opposing arch, vertical intra-arch eruptive forces
can be produced using superelastic coil springs. A horizontal helix is bent in a
continuous rectangular archwire at the position of the impacted tooth . A stainless
steel ligature tied to a Monkey Hook is directed vertically through this helix. The
ligature is then tied to the eyelet of a superelastic closed-coil spring attached to the
first molar.
Fig 46 Monkey Hook
Implant Supported Deimpactor System
In this, an orthosystem palatal implant is used for anchorage in the treatment of
impacted maxillary canines.
Type I
Two lingual sheeths with rectangular opening are soldered to a steel cap,which is
attached to the palatal implant. .032
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for maxillary molar distalization. Two 0.040
mesial portion of the steel cap for initial extrusion.
Type II
0.032
extrusion of impacted canine in the vertical plane.
Fig 47 Implant Supported Deimpactor System
Ballista spring 63
It was designed by Harry Jacoby (1979). It is a 0.014, 0.016 or 0.018 inch round wire,
which accumulates its energy by being twisted on its long axis. Distally it passes
through both headgear and edgewise vestibular tubes of the first or second maxillary
molar and it is ligated to this tube so that it cannot rotate in the tubes.
The horizontal part of the wire accumulates the energy and is ligated on the first
premolar allowing it to rotate in the slot of the bracket as a hinge axis. The last part
of the spring (mesially) is bent down vertically and ends in a loop shape to which a
ligature elastomeric thread can be attached. When the vertical portion of the spring is
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raised toward the impacted tooth, the horizontal part accumulates the energy into the
twisted metal. When the vertical section is released, it bumbs down like a
(Roman missile).
The anchorage for molar is through a transpalatal 0.045 inch wire.Since premolars
(upper 4
Force of the spring is proportional to the diameter of the wire and to the length of the
horizontal and vertical parts of the spring. A 0.016 inch spring of average size
provides a force of 60-100gms;a 0.018 inch spring of average size provides a force
of 120-150gms. For a normal case, it is advised to start with a 0.016 inch wire and to
change it to a 0.018 inch after a month. If , after 2 months of treatment, no progress is
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registered, because of severely impacted canines or tissue resistance, one can add a
second spring in the same tube to increase the force operating on the impacted tooth.
Kilroy spring64
The Kilroy Spring is a constant force module that is slid onto a rectangular archwire
over the site of an impacted tooth. The configuration of the Kilroy Spring reminded
the designers of the popular
state, the vertical loop of the Kilroy Spring extends perpendicularly from the occlusal
plane (Fig. 2). 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. A Kilroy Spring can be tied to a loop-button, a Monkey
Hook, 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. In this
arrangement, called the Kilroy I, both lateral and vertical eruptive forces are directed
to the impacted tooth The Kilroy 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; an orthodontic bracket or a new loop-button is then direct-
bonded to the tooth to continue moving it into the arch. If the tooth is rotated, a
second loop-button can be bonded to the opposite side, and Monkey Hooks with
elastic chains can be used to create a rotational couple
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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 adjacent soft tissue.
Consequently, more frequent progress checks are recommended with the Kilroy II.
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Tunnel traction65
Deep infraosseous canines associated with persistent deciduous teeth may be
successfully and safely treated by repositioned flap and tunnel traction toward the
center of the alveolar ridge. This consists of raising a full thickness flap to expose
the cortical plate. The deciduous canine is then removed. Cortical bone is removed
to provide access to the crown and the follicular socket is eliminated. A low speed
bur is inserted into the seat of the deciduous tooth
bone under careful cooling to reach the crown of the impacted tooth (canine). The
perforation and the deciduous socket forms a tunnel that is used for traction. A
handmade wire (ligature) chain of rings approximately 1.5mm in diameter is prepared
with 0.011 osseous tunnel and fixed as
closely as possible to the cusp of the impacted canine by means of an attaching
device (bonded button/bonded bracket base/ anatomically continued fine mesh) The
flap is then repositioned and sutured in its original seat. The chain passes through the
bone tunnel and emerges from the socket of the deciduous tooth. The traction phase
is started after one week when sutures are removed and directed to the center of the
alveolar ridge.
Advantages
No attachment loss and no recession are observed at the end of active therapy.
No significant differences in keratinised tissue are observed between test and
control teeth at the follow-up examination.
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Deep infraosseous canines associated with persistent deciduous teeth may be
successfully and safely treated by repositioned flap and tunnel traction toward the
center of the alveolar ridge.
Full thickness flap raised
Decideous canine extracted
Cortical bone removed to provide access to crown
Follicular socket eliminated
Low speed bur through socket
Formed tunnel is used for traction
Handmade ligature chain 1.5mm length bonded button 0.011"
Flap repositioned
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The chain passes through the bone tunnel and emerges from the socket of the
deciduous tooth. Traction phase started after one week when sutures are removed and
directed to the center of the alveolar ridge.
Active Palatal Arch (Becker 1978)12
Cantilever Mechanics 66
It is an efficient Bio mechanical choice, because all the forces can be measured and
thus controlled. A typical cantilever design is a wire fully engaged in the bracket of
one tooth and tied in a point contact to another tooth. Cantilever system producing
extrusive force at single point contact with labially impacted canine, intrusive force
and counter clockwise moment at first molar.
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Active Force
Cantilever is made from 0.017" x 0.025" TMA
Generates 25 - 30 g of force.
Reactive Forces
At the molar the cantilever will produce an equal and opposite intrusive force, as well
as a counter clockwise moment that tends to tip the molar mesially.
These two reactive forces do not present a clinical problem as long as the extrusive
force is kept within 25 - 30 gms.
Rare Earth Magnets And Impaction67,68
Early work with magnets involved the use of cobalt platinum alloy magnets. Since
they costed several thousand pounds per kg prevent frequent experimentation.
An alloy of Al, Ni & Co., was then used owing to its favourable length diameter ratio
(compared with samarium cobalt ). Due its larger flux leakage the adjacent tissue
were exposed to larger fields and the tissue effects could be studied. Human
experiments were then carried out using samarium-cobalt alloys, as the stored energy
and forces were far superior to the Aluminium Nickel Cobalt Magnets.
Recently, an alloy, Neodymium-Iron-Boron has become available in various shapes
and sizes for attachment to teeth. Produced by a powder metallurgy process, they
provide the highest energy per unit volume of any commercially available magnetic
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material. They are 70% more powerful than the same size samarium cobalt magnet.
They are supplied in a magnetized condition with an electroplated tin protective
finish, but they are brittle and need to be handled with care.
The unique characteristics of permanent rare earth magnets are suitable to counter
side effects adjunct to impaction. The cardinal problem of impaction is the
premature exposure of the impacted tooth to the oral environment.
A direct consequence of this measure is a non self-cleansing area that invites the
vicious cycle of infections pathway, inflamed gingival tissue, apical migration of
epithelial attachment, bony recession and exposed CEJ.
Advantages of using magnets for management of impacted teeth:
Avoidance of the need for traction. Hence both operator and patient friendly.
Magnets produce a low continuous force that actually increases over time.
Hence a more physiological force is performed and stimulation of the normal
eruption process.
A balanced ratio of CEJ to alveolar ridge, attached gingiva, free gingival fibres
and epithelial attachment is maintained.
More versatility (can be used with premolars and molars also, in addition to
incisors and canines)
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J.P. Sandler suggested a technique which involves attachment of a prepared
3x3x1mm NdFeB magnet to the unerupted tooth with the acid etching . A light cured
system is the preferred method, as the setting time is greatly reduced as compared
with chemical curing. Therefore fewer problems with moisture contamination are
likely to be encountered.
Preparation of the magnet involves tying a thin S.S.ligature around it and then
coating this unit with unfilled composite resin. The ligature acts as a handle for the
magnet at operation and also ensures that the magnet is bonded to the tooth with the
correct orientation. The composite resin provides an impermeable barrier preventing
any ionic diffusion that would lead to corrosion as well as facilitating the attachment
of the magnet to the unerupted teeth at operation. Some freshly mixed composite is
added to the
unerupted tooth. The second larger magnet (5x5x2cms) is incorporated into a
removable appliance. It is completely surrounded by the acrylic of the appliance,
which gain will prevent ionic diffusion that would lead to corrosion. Careful
positioning of the two magnets (in attractive mode) is essential to ensure optimal
direction of pull. This method is particularly useful when a palatal direction of pull is
required to prevent the tooth form erupting through the buccal gingiva.
The only adjustment that is sometimes required is the repositioning of the larger
magnet 2-3mm occlusally once the 2 magnets are in opposition. Provided that the
working model is available, this is an easy operation to be carried out at chair side
with a cold cure acrylic and a spacer. It is often useful to have an anterior bite plane
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on the appliance to prevent excessive occlusal forces on the arc of the larger magnet
as well as to allow room for the adjustment.
Vardimon suggested a new magnetic attraction system with a magnetic bracket
bonded to an impacted tooth and an intraoral magnet linked to Hawley type retainer.
Vertical and horizontal magnetic brackets were designed with the magnetic axis
magnetised parallel and perpendicular to the base of the brackets respectively. The
vertical type is used for impacted incisors and canines and the horizonal magnetic
bracket is applied for impacted premolars and molars.
Open window approach to uncover the impacted canine to which was bonded a
vertical magnetic bracket with the magnetic axis parallel to the mesh base. The
uncovered tooth with its bounded magnetic bracket was packed with wonderpack
dressing to prevent healing over the palatal mucosa. Before surgery, palatal
impression had been made and a Hawley retainer type appliance was fabricated.
4 days after surgery patient examined and removable maxillary appliance fitted. A 1
cm hole cut in the acrylic, directly below and slightly antero labially to the uncovered
canine. A 2.54mm Neodymium Iron Boron spacer was placed on the magnetic
bracket in at
