management of maxillary impacted canine.

1. MANAGEMENT OF
MAXILLARY IMPACTED
CANINE

2. OUTLINE
 INTRODUCTION
 DEFINITION
 EPIDERMIOLOGY
 EMBRYOLOGY
 MANAGEMENT
 HISTORY
 CLINICAL EXAMINATION
 TREATMENT OPTIONS
 SEQUELAE
 COMPLICATION
 CONCLUSION

3. DEFINATION AND INTRODUCTION
 Impacted canine are problems frequently encountered in dental practice.
 Success in management and development of a satisfactory treatment plan requires
a team effort
 An impacted tooth is said to be whose eruption is considered delay and for which
there is clinical or radiological evidence that further eruption might not take place
as oppose to ectopic eruption
 Ectopic eruption is a tooth developing beyond the range of the normal eruption
path or malposition of a normal permanent tooth bud resulting in eruption into the
wrong place

4. EPIDERMIOLOGY
 The displacement or failure of max. canine are frequent clinical problems
 This is due to their importance which include
 Long root and excellent bony support
 Its resistance to caries and periodontal diseases
 Aesthetic value to arch
 Occlusal canine guidance during excursive movement

5.  It is the 2nd only to mandibular 3rd molar in frequency of impaction
 The prevalence of about 1.5 – 2% in Caucasians, (Grover et al., 1985, Cramer and
Rohrere and Bass et al) with a frequency of about 2.07% in Nigerian orthodontic
population (Isiekwe and Logan)
 It is twice as common in girls than boys (Rohre 1929) however Rayne 1969 found
no sex predilection but Thiland reported a slight increase in frequency in male.
 It is found palatal to the arch in 85% of cases while the lingual/buccal impaction is
15%

6.  Majority of palatal impaction have adequate space for eruption while majority of
labial impaction have inadequate space for eruption usually due to crowding
 Individuals with class 2 division 2 malocclusion and tooth aplasia may be at higher
risk of developing ectopic canine

7. DEVELOPMENT OF MAX. CANINE
 According to Broadbent in 1941 the permanent maxillary canine begin calcification
at approximately 4-5 month of age between roots of deciduos molars.
 Calcification is completed by age 5-6years after which the deciduous molar have
erupted and its left behind
 By 3-4years it has moved to lie labial to the root of lower deciduous lateral incisors
 At age 4 years it lies in vertical with D,4,3, and with subsequent forward growth of
the jaw it lie medial to C and remain high in the maxilla

9.  By age 7years the canine is mesial to root of C with vertical overlap of about 3mm
 By age 8 the canine move buccally from palatal position, some fail to move at this
stage leading to palatal impaction
 With increase in size of subnasal area, the canine moves downward forward and
laterally away from root end of lateral incisors
 By age 8-12years the ugly duckling stage it travels along the root of lateral incisors
and assume a more errect posture leading to final eruption between the 2 and 4

10.  By eruption the canine has travelled about 22mm and ¾ of the root has been
formed with root completion at 2 years after eruption
Gingival emergence of canine
 Female after 12.3yrs: male 13.1yrs was late. (Hurme, 1949)
 Female after 13.9yrs : male 14.6yrs late (Thilander et al ., 1968)

11. Calcification and eruption of maxillary
canines
 Calcification begins 4 months
 Enamel complete 6-7 years
 Eruption 11-12 years’
 Root completed 13-15 years
 Important anatomical risks are
 Longest course of development
 Deepest area of development
 Most circuitous path of eruption

12. Aetiology
 Multifactorial
 General or Local factors
 It may also be
 Genetic
 Local environment
 Systemic environment

13. Genetics
 Hereditary
 Mal-positioned tooth germ
 Shortened arch length
 Alveolar cleft

14. Local environmental
 Prolonged retention of primary teeth
 Reduced root length of adjacent lateral incisor/loss of guidiance
 Ankylosis of permanent canine
 Degree of dental crowding and spacing
 Failure of primary canine root to resorb
 Small or congenitally missing lateral
 Long path of eruption
 Arch length discrepancy/ inadequate arch space
 Trauma

15. Systemic environmetal
 Endocrine deficiency
 Febrile diseases
 Hereditary gingival fibromatosis
 Down syndrome
 Cleidocranial dysostosis
 Irradiation
 Vitamin D deficiency

16. Aetiology continued
 There are two common causes of palatally erupting canine
Guidance theory
Genetic theory
Guidance theory: loss of tooth guidance which include
 Congenitally missing 2
 Diminitive 2
 Supernumerary tooth
 Odontomes
 Transposition of tooth
 Retained primary canine

17. Genetic cause of impaction
 Palatally impacted maxillary canine are often present with other dental
abnormalities, including tooth size, shape, number and structure. (Baccetti et al)
 Zibermann in 1990 found that relatives of patient with palatal canines are likely to
exhibit palatally displaced canine
 33% of patient with palatally impacted cuspids also have congenitally missing
teeth. (Peck et al)
 47.7% of patient with palatally impacted cuspids have small peg shaped lateral or
missing lateral incisors (Brin et al)

18.  Baccetti also see association with hypoplastic enamel, infra-occluded primary
molars and aplastic second bicuspid
 It is uncertain whether the anomalous lateral incisor is a local causal factor for
palatally diplaced canines or genetic developmental influence. (Peck et al)

19. Management
 Early detection of impacted maxillary canines may reduce treatment time,
complexity, complication and cost
 Ideally, patients should be routinely screened as from 8 years to determine if
canine will be displaced from normal position in the alveolus and assess the
potential for impaction.
 Management is often multidisciplinary in approach involving restorative dentist,
oral surgeons, periodontologist as well as Orthodontist

20. History
 Age of patient
 Age the C’s were lost or retained
 History of trauma
 General health of the patient
 Family history

21. Examination
 The clinician can investigate the presence and position of the canine using 3 simple
,methods
 Visual inspection
 Palpation
 Radiographic evaluation
 According to moss the following must be considered during clinical evaluation of
the patient
 The amount of space available in the arch for unerupted canine
 The contours of the bone
 Mobility of the primary canine or lateral incisors

22.  Radiographic assessment to determine position of the canine, its apex, crown,
direction and state of the root.
 Inspection – this is recommended at age 8
 Presence of retained C or supernumerary
 Displacement of lateral incisors
 Bulge of palatal or buccal bone or its absence
 Missing 3

23.  Odontomes
 Distal inclination with physiological diastema
 Labial tilt or palatal tilt
 Periodontal conditions
 Oral hygiene
 Palpation
 Tooth mobility of the primary canine or permanent lateral incisors
 Bulging on the palatal or buccal plate of bone

24.  Suspicion of an impacted 3 is made when
 The canine is not palpable in the buccal sulcus by the age of 10-11years
 If there is a bulge (palatal or canine/lingual/buccal) suggestive of ectopic
eruption
 Loss of tooth vitality or increase mobility of permanent maxillary lateral incisors
 In patients older than 10years, an obvious palpable bilateral asymmetry could
indicate that one of the permanent canine is impacted or erupting ectopically

25. Radiographic investigation
 This is done to aid in the localization of the unerupted tooth as well as to assess
adjacent structure
 It also aid to determine the angulation height and mesiodistal position of 3
 It aids to see pathology around the root and root resorption if any

26. Conventional radiograph
 Periapical
 Standard upper occlusal
 Orthopantomogram
 Lateral cephalometry

27.  Computed Tomography
 Magnetic Resonance Imaging

29. Localization
 This is best achieved by taking at least 2 views from different angles using the
clark’s rule (Buccal Object rule)
 The 2 most important radiographic method for localization of impacted canine are
 The parallax method
 The magnification method

30. Parallax technique
 This is also known as the tube shift method, Clark’s rule or Buccal object rule
 It is carried out using combinations of radiographs
 There are 2 types
 Horizontal parallax – Anterior occlusal and periapical or 2 perapicals
 Vertical parallax – Anterior occlusal (70-750) and optical projection tomography or
periapical and OPT
 Recent studies has shown that the horizontal parallax technique is more reliable
than the vertical technique in localizing unerupted canine (Armstrong et al.,2003)

32. Horizontal parallax technique
 Its done using two periapical films taken at different angles with the same vertical
angulation or at the same point
 Based on this principle the more distant object appear to move in the same
direction of the tube shift while closer object move in opposite direction
 Based on SLOB (Same lingual opposite buccal) principle, if the object has moved
on the same side as that of the X-ray tube, it is said to be lingually placed and if it
has moved on the opposite side it is on the buccal side. If the teeth does not move
then it is correctly positioned.

33. Other combination based parallax
 1 upper anterior occlusal and 1 upper lateral occlusal
 1 periapical and 1 upper anterior occlusal
 OPG and upper anterior occlusal
 OPG alone when a panorex machine is used

34. Magnification
 This is based on the principle of image distortion for a given focal spot, field
distance
 Object further away from the film will be depicted more magnified than object
closer to the film
 This can be applied in a panoramic view (Fox et al., 1995)
 If 3 is relatively magnified in comparism with the adjacent tooth in the arch or
contralateral canine then it is located near the tube or palatal
 If relatively diminutive, it is located away from the tube i.e labially

35.  This method is effective if
 3 is not rotated of in contact with the incisor root
 Incisor is not tipped
 Classification based on magnification method
 Buccal ; when there is diminutive impacted 3
 In the arch; 3 has same magnification as adjacent tooth
 Palatal; when there is magnified impacted crown of 3

36. Importance of conventional radiography
 PERIAPICAL – This gives the localization of the tooth and indicates the inclination. It
allows for assessment of the degree of root resorption of the lateral incisor or
primary canine.
 OCCLUSAL - Anterior and oblique occlusal maybe used to assess the depth of the
tooth
 CEPHALOMETRIC & POSTERO ANTERIOR -Used to determine height, depth and
inclination of the canine.

37.  PANORAMIC
 Helps to determine the depth, inclination and the relation to the standing
teeth.
 It gives the overview relationship of the tooth to the other structures.
 Shows presence supernumerary tooth, odontome or some other pathology.

38.  Ericson and Kurol found that periapical radiographs allowed accurate location of
the teeth in 92% of the cases they evaluated.
 Periapical films are diagnostic for transverse position.
 Occlusal radiographs are more accurate for determining the positions of the
canines relative to the midline
 Lateral cephalometric radiographs are also helpful in assessing the anterior–
posterior position of the displaced tooth, as well as its inclination and vertical
location in the alveolus.

39. Limitation of conventional dental radiographs
 Lack the accuracy necessary for assessing palatal or buccal root resorption of the lateral incisor
 Gives 2 D imaging

40. Factors that influence the overall treatment and
prognosis
 Confirmation of presence or absence of the canine tooth.
 Length and stage of root formation.
 Size of eruption follicle.
 Inclination of the long axis of the tooth.
 Relative buccal-lingual position of the tooth.
 Amount and quality of bone covering the tooth.

41.  Proximity and resorption of roots of adjacent teeth.
 Condition of adjacent teeth.
 The type of mucosa covering the impacted tooth.
 The overall stage of dental development.

42.  Assessment of these factors can be challenging with conventional radiographic
methods, due to limitations of 2-D imaging.
 Superimposition of structures on the film can make it very difficult to distinguish
details.
 Distortion and projection effects are also encountered.

43. Computed tomographic scanning (CT)
 Provides excellent tissue contrast.
 Eliminating blurring and overlapping of adjacent teeth.
 Offers orthogonal views eliminating projection effects.
 Improved visualization.
 Limitation of CT include it high cost and high radiation expose.

44. Cone-beam computed tomography
 In recent years, 3-D volumetric imaging has been developed specifically for
dentistry. James mah et al 2003. (CBCT)
 It offer reduced cost relative to medical CT
 significantly reduced radiation exposure.
 It helps clinician to asses damage to the roots of adjacent tooth
 It can asses the amount of bone in relation to each individual tooth

45. Treatment
 Multidisciplinary
 Problem listing
 Prognosis for alignment must have been evaluated
 Factors involved in determining treatment options are
 Age and level of cooperation
 General oral health and periodontal/periapical status
 Skeletal pattern and availability of spacing or crowding
 Position of the 3 on the occlusal plane
 Resorption of the root of adjacent tooth

46. Treatment options
 Interceptive
 Surgical exposure with orthodontic traction
 Open surgical exposure with spontaneous eruption
 Open surgical exposure with packing and subsequent bonding of an auxillary.
 Closed surgical exposure and bonding of an attachment intraoperatively.
 Surgical repositioning and alignment
 Surgical Autotransplantation
 Surgical removal
 No treatment.

47. Interceptive Treatment
 In Class I non crowded situations where the permanent maxillary canine is
impacted or erupting buccally or palatally, it may be the preventive treatment of
choice in patient 10-13 years old.
 However, intercept early if
 There is any root resorption
 3 not palpable in its normal position and radiographic examination confirms
palatal ectopia
 When canines are impacted buccally, retained primary canine should be extracted.

48.  Power and Short reported 62% success rate after interception in a crowded arch.
 Ericson and Kurol reported 78% success of palatally erupting 3, the eruption paths
normalize within 12 months.
 However, interception does not guarantee correction or elimination of the
problem.
 If NO radiographic evidence of improvement seen one year after treatment, then
surgical exposure and orthodontic eruption, is indicated.

49.  The success of early interceptive treatment for impacted maxillary canine is
influenced by
 The degree of impaction - if its exceeds half the width of the lateral incisor root
to the midline, the chances for complete recovery are poor.
 Age at diagnosis.
 canine angulation
 crowding.
 Clinical studies by Erricsson and Kurol reported resolution of palatal impaction in
91% of cases in which the tip of the crown of the canine is distal to the midline of
the lateral incisor when treatment is initiated

50.  The success rate drops to 64% if the cuspid crown is positioned mesial to the
midline of the lateral incisor before interceptive treatment
 Power and Short found that an angle exceeding 310 from the vertical significantly
reduces the chance of normal eruption following an extraction.
 Ericson and Kurol found that more (horizontal angulation ) mesially positioned
canine cusp tips are associated with greater resorption of lateral incisor roots.

51.  Other adjunct to spontaneous eruption will include
 Cervical pull headgear
 Double extraction of C and D

52. Surgical Exposure with orthodontic traction
CONSIDERATION
 Patient must be willing to wear orthodontic appliance
 Patient must be motivated to maintain good OH
 Interceptive measures not suitable
 Position of malposition not too great to preclude treatment.
 The long axis of the 3 should not be too horizontal or oblique
 The optimal time for alignment is during adolescence.

53.  Prognosis must be good
 Age of the patient
 Presence of spacing or crowding
 The spatial orientation of the crown and root of 3. i.e vertical. A-P. transverse
 The degree of inclination of 3. prognosis is poorer if >450
 The closer the 3 to the midline, the poorer the prognosis.

54.  3 must not be ankylosed
 The root of 3 should not be dilacerated
 The deeper the depth of 3 in the bone the poorer the prognosis.
 The long axis of the 3 should not be too horizontal or oblique
 The closer the root of 3 to the midpalatal suture the poorer the prognosis. Kurol et
al 1997

55. METHODS ( MCSHERRY 1996)
 Open surgical exposure with spontaneous eruption
 Open surgical exposure with packing and delayed bonding of an auxillary.
 Closed surgical exposure and bonding of an attachment intraoperatively.
 For surgical exposure 3 surgical approach can be used
 1. Replacement flap technique
 2. Excisional exposure
 3. Apically position flap
 The goal is to choose a technique that exposes the canine within the a zone of
keratinized mucosa without involvement of the cementoenamel junction

56. Open surgical exposure with spontaneous
eruption
 Canine must have a correct inclination
 Usually has only soft tissue covering
 The technique involve excision of the gingivae over the canine with little exposure
of the crown and bone removal.
 This should be enough to allow eruption of the canine

58. Open surgical exposure with delayed packing
and then subsequent bonding of an auxillary.
 The packing is remove after a week postop and an attachment bonded with
subsequent traction using a fixed appliance.
 Beckel et al; study showed evidence of periodontal compromise
 Adv
 Re-bonding can be done under direct vision
 Direct visualisation during movement.

59. Closed surgical exposure and bonding of an
attachment intraoperatively
 Palatal mucoperiosteal flap is raised
 An attachment is bonded intraoperatively to the crown of 3 to facilitate
orthodontic alignment using fixed appliance using traction.
 Advantages
 More esthetic outcome
 Post op comfort to the pt
 Disadvantages.
 Re bonding involve another surgery
 No direct visualisation during movement

61.  For a buccally ectopic Canine, and for better esthetic, It is important to use either
 Close technique or
 An apically repositioning flap to preserve the attached gingiva
 Vermette et al 1995 compare both method and reported a better esthetic
appearance with close technique.

62. Attachments
 Lasso wires
 Threaded pins
 Orthodontic bands
 Standard orthodontic brackets
 A simple eyelet
 Elastic ties and modules
 Magnets
 Gold mesh disk with a gold chain

63. Lasso wires
 It is twisted lightly around the neck of the canine
Disadvantages
 This result in irritation of the gingivae
 Prevent reattachement of the healing tissue in the arear of CEJ
 May reduce arears of external resorption and ankylosisi

64. Threaded Pins:
 Provide the attachment for an impacted tooth.
 Disadvantages: -
 Dentally invasive. Requires a subsequent restoration. –
 Difficult to place along the long axis of the tooth because of smaller surgical
exposure. –
 The drilled hole may inadvertently enter the pulp(unerupted teeth may have large
pulp chambers). So it is rarely used.

65. Threaded pin

66. Orthodontic bands
 They largely replace the Lasso wires & threaded pins.
 Advantage:
 They are compatible with the health of periodontal tissues.
 Disadvantage: -
 Large surgical field required.
 Inadequate moisture control may hamper the cement-band bond.

67. Band

68. Standard orthodontic brackets
 Any of edge-wise , Begg’s , PAE brackets can be used.
 They are routinely used as direct attachments along with the composites.
 Disadvantages: -
 As the bracket base is wide, it is difficult to adapt to any other tooth surface except
for the buccal surface. –
 The bracket’s shear bulk creates irritation as the tooth is drawn on the soft tissues.
 Ligature wire or elastic thread is tied to bring the impacted tooth into arch.

70.  Interferes with the investing tissues & leads to inflammation & periodontal
damage.
 As the impacted tooth advances into the arch the exuberant gingival tissues
bunches in front of it & causes punching between the bracket & tissues.

71. Simple Eyelet
 Advantages: -
 An eyelet welded to band material with a mesh backing is soft & easy to contour
making its adaptation to bonding surface more accurate which makes for superior
retentive properties. –
 Because of small size they can be placed in more awkwardly placed teeth.
 It is less irritating to the surrounding tissues

72. Elastic ties and modules
Advantages
 Application of light forces - Good range of action - Easier to tie
Disadvantages
 Tends to loosen - High degree of force decay

73. Magnets
 It is made up of rare earth lanthanide alloys .
 It is rarely used.
Disadvantage: -
 corrosion

74. Gold mesh disk with a gold chain

75.  The gold mesh disk with a gold chain is the device of choice
 It also work better than bracket or button with the light cure bonding agent
because the curing light get at all the bonding agent through the mesh

76. Use of gold chain

77. Biomechanical consideration
 Light force of magnitude of 20-60g should be applied to align the canine. Bishara
1994
 The provision and maintenance of adequate space of canine is very essential.

78. Method of alignment
Different methods have been described for alignment. Hunter et al 1983
 Fixed appliance with a transpalatal or headgear
 Application of force can be in the form of elastic or wire traction.
 Usiskin in1991 described the use of gold mesh disk with a gold chain bonded to
the crown of 3 to apply traction.
 A palatal arch with a soldered hook attached can also be use as traction
 Jacoby 1979 also describe the use of ballista spring ( SS 0.012 inch wire)

79.  Roberts – Harry et al 1995,describe the use of sectional approach using 0.017 by
0.025 inch TMA sectional archwire from the 6 to the 3 using a transpalatal arch for
anchorage
 Bennett and Mclaughlin 1997,describe the use of a wound made of 0.014 inch steel
on to a 0.019 by 0.025 inch SS as traction to achieve first vertical movement and
then lateral movement.

80.  Orton et al 1995 described the use of a lower removable appliance with a hook
soldered on the crib to which traction is applied by a gold chain on the crown of
the tooth.
 Darendelilier et al 1994, also described the use of magnet to apply force to align
the tooth.

81. Retention
 In treated cases of ectopic canine, many studies has shown
 Spacing and rotation in 17.8% of cases
 Noticeable relapse, intrusion, mesial rotation and lingual displacement in 40% of
cases treated in an average of 3 years and 7 months post treatment.
 21% of pulpal obliteration and 75% cases of discoloration was also seen. Woloshyn
et al 1994

82.  To prevent relapse, bennett et al 1997 suggested
 Good buccal overlap and correct root positioning
 Full correction of torque
 Early correction of rotation
 Circumferential supracrestal fiberotomy (Pericision)
 Provision of a bonded retainer

83. Surgical repositioning and alignment
 It suitable for tooth which are only mildly displaced.
 It involves de- rotation of the impacted canine within its socket
 It defer from transplantation because effort is made to avoid removal of the tooth
from it socket
 The greater the displacement the poorer the prognosis as frequently the
neurovascular bundle are broken

84. Autotransplantation
 Considered;
 If patient is unwilling to wear orthodontic Appliance
 If the degree of malpositioning is too great for orthodontic alignment.
 Optimal time is when the root is about 50-75% formed
 Interceptive measure not appropriate or had failed

85.  Adequate space btw the 2 and 4 and there is sufficient alveolar bone
 The 3 can be removed atraumatically
 The prognosis is good for transplantation
 No evidence of root ankyloses, dilacerations or root resorption
 Fixation at d recipient site is done using a preformed or vacuum splint which covers
the entire upper arch
 Splint is removed after 3-6wks and this is followed by bonded sectional fixed
appliance

86.  Early studies gave disappointing results with a high frequency of root resorption
after transplantation, but meticulous atraumatic surgical removal and stabilization
of transplanted tooth for six weeks followed by endodontic treatment has shown
better result

87. Surgical removal
Its an option when there is ;
 Poor patient cooperation
 Patient decline treatment or is pleased with the appearance
 The tooth is lying in an unfavorable position (3 in horizontal position) and there is
insufficient space in the arch
 Presence of a pathology.
 Satisfactory occlusion and prognosis for treatment is poor.
 Evidence of early resorption of adjacent tooth.
 Good contact btw the 2 and 4,so as to substitute 4 for 3.

89. Rehabilitation
 Rehabilitation is needed if the canine was extracted and there is an edentulous
space which is aesthetically unpleasing.
The following could be done;
 Fabrication of a removable partial denture
 Replacement of tooth with a bridge
 Use of implants

90.  Implants as an option? It is important to remember that implants in a growing child
will ankylose and appear to submerge as the alveolus continues to develop. These
are not therefore an option until the patient is at least 20 years of age

91. No active treatment; leave and observe
 Recommended when
 Pt does not want treatment
 No evidence of resorption of adjacent tooth or other pathologies
 Good contact btw 2 and 4
 Good esthetics
 Good prognosis for primary canine
 If removal will cause damage to adjacent or vital structure.

92. Sequelae of ectopic canine
 Internal and external root resorption of adjacent is the most common.
 Ericson et al 1987; reported 12.5% resorption of incisor adjacent to ectopic 3
 Postletwaite 1989; resorption more in 2 than 1 and rare in 4
 Rimes et al ; female more affected than male

93.  Ericson et al 1988; risk of resorption increase by 50% if the the angulation of the
long axis of ectopic 3 exceeds 25% to the midline of OPG.
 2 are more commonly resorbed palatally and at the mid root level than at cervical
or apical region. Ericson et al.
 Cystic degeneration is uncommon. Ericson et al reported no evidence of cystic
degeneration
 Late resorption of the ectopic canine itself
 Loss of tooth vitality of the incisor
 Poor esthetic associated with the C’s
 Late eruption of impacted 3 under a prosthesis

94. Risk associated with surgical intervention
 Damage to adjacent teeth
 Re exposure may be require
 Risk of anesthesia
 Risk associated with orthodontic treatment
 Root resorption
 Decalcification
 Periodontal problem
 Canine ankylosis
 Failure to complete treatment.

95. conclusion
 Problems associated with unerupted canine has generated a
lot of interest particular the mode of treatment modalities.
However other features of occlusion and most especially
patient cooperation in the light of prolong orthodontic
treatment may have a significant bearing on its management.

96. Thank you

97. References
 Orthodontic treatment of impacted teeth - Ardian Becker 2) AJO 1983 Aug 125 –
132
 The etiology of maxillary canine impactions - Jacoby 3) AJO 1994 Jan 61 – 72
 Tunnel traction of infraosseous impacted maxillary canines - Crescini, Clauser,
Giorgetti, Cortellini, and Prato 4)AJO 1982 Mar 236 - 239 Txt
 Orthodontic considerations in the treatment of maxillary impacted canines -
Fournier, Turcotte, and Bernard AJO1991 Dec 494 - 512 Txt
 Rare earth magnets and impaction - Vardimon, Graber, Drescher, and Bourauel.
 Seminar in orthodontics - management of impacted teeth.
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