March, 2011

Transmigration of mandibular canines- 2 case reports and review of literature.

1)     Dr. Priyanka Mahaajan, BDS

Post Graduate student

Dept. of Orhthodontics and Dentofacial Orthopaedics,

KLE V.K Institute of dental sciences,

Belgaum, Karnataka.

Tel no. 9620846359.

Email address:prankymahajan@gmail.com

2)     Dr. Sujala Durgekar BDS, MDS

Assistant Professor

Dept. of Orhthodontics and Dentofacial Orthopaedics,

KLE V.K Institute of dental sciences,

Belgaum,Karnataka.

3)     Dr. Kanhoba Mahabaleshwar Keluskar BDS, MDS,

Professor and Head of the department,

Dept. of Orhthodontics and Dentofacial Orthopaedics,

KLE V.K Institute of dental sciences,

Belgaum, Karnataka.

Introduction:

Migration of mandibular canines across the midline is referred to as ‘transmigration.’ ¹

Ando et al ² were the first to use the term ‘‘transmigration.’’ Tarsitano et al³ defined transmigration as the phenomenon of an unerupted mandibular canine crossing the midline. Javid⁴ elaborated the definition to include cases in which more than half the tooth had passed through the midline.

Failure of eruption of the mandibular canine is an unusual event.⁵ Shah et al⁶ found 8 unerupted mandibular canines in 7886 individuals. Grover and Lorton⁷ found 11 impacted mandibular canines in 5000 individuals.

An unerupted tooth sometimes  migrates to a location a little  distance away from the site in which it developed, but it usually remains within the same side of the arch. The mandibular permanent canine is the only tooth in the dental arch reported to migrate across the midline. ⁵ Javid⁴ found one such case in 1000 students. In doing so, the tooth usually travels along the labial side of the incisor roots and migrates as far as the roots of the first molar on the opposite side.

Case Reports:

Case 1 -

The patient, a fit 14-year-old boy, was referred to the Department of Orthodontics, KLE VK institute of dental sciences for investigation of an unerupted lower left and right permanent

mandibular canine. His dental history was one of irregular attendance with no previous extractions.  Intraoral examination found a Class I incisor relation with mild crowding in the lower left premolar/canine area and a well-aligned upper arch.(Fig: 1)

Fig. 1

Radiograph showed two unerupted, transmigrated teeth lying close to the lower border of the mandibular symphysis. (Fig. 2)

Fig. 2

The proposed plan for this was routine radiographs to check if any cystic degeneration seen and the canine which was interfering the apices of roots of the lateral incisors was decided to be extracted.

Case 2 -

The patient, a fit 24-year-old female, was referred to the Department of Orthodontics, KLE VK institute of dental sciences for crowding in lower arch. Her dental history was one of irregular attendance with no previous extractions.  Intraoral examination found a Class I incisor relation with mild crowding in the lower left premolar/canine area and a well-aligned upper arch.(Fig.3)

Fig. 3

Radiograph showed one unerupted, transmigrated teeth lying close to the lower border of the mandibular symphysis.(Fig.4)

Fig. 4

The proposed treatment plan for this case was to take a series of successive radiographs

periodically.

Discussion:

Transmigration of an unerupted tooth is generally a unilateral phenomenon, although 16 cases of bilateral transmigration have been reported.⁸ Joshi⁹ observed four cases of bilateral transmigration among a collection of 28 cases. The left canine is more involved than the right canine. The incidence of transmigrated canines is much higher in females than in males. In the literature, transmigrated canines have been reported in 87 females and 57 males. Gender was not mentioned in ten of the cases.¹

Nodine¹⁰ has described the condition in prehistoric skulls. Thoma⁸ appears to have been the first to describe this anomaly in living patients. Subsequently, different authors have described cases of various transmigrated mandibular canines.

Greenberg and Orlian¹¹, over a 30- month period, followed the transmigration of a normally positioned unerupted mandibular left canine to a position of horizontal impaction below the apices of the four incisors. Howard¹², Kerr¹³, and Wertz¹⁴ also cited cases where an apparently normal lower canine, for no apparent reason, tipped mesially and started to migrate across the lower incisors. A permanent canine within a dentigerous cyst may transmigrate due to the cystic pressure.

Mupparapu ¹⁵ used five criteria to classify the transmigrated canines. These are summarized

as follows:

• Type 1: The canine is impacted mesioangulary across the midline, labial, or lingual to the anterior teeth with the crown portion of the tooth crossing the midline.

• Type 2: The canine is horizontally impacted near the inferior border of the mandible below the apices of the incisors.

• Type 3: The canine has erupted either mesial or distal to the opposite canine.

• Type 4: The canine is horizontally impacted near the inferior border of the mandible below the apices of either premolars or molars on the opposite side.

• Type 5: The canine is positioned vertically in the midline with the long axis of the tooth crossing the midline.

Most of the cases reported in the literature are Type 1.^1,2,3,6,13 In the present report, all the  canines exhibited a Type 4 transmigratory pattern.

Howard¹⁶ expected the older patient would show a greater distance of travel because a

longer time had been available for the migratory canine to travel. Ando and coworkers² observed

transmigration in their patient for six years. During this time, the canine moved from its

original position to a place near the mental foramen on the opposite side. Out of five cases

according to Al-Waheidi¹⁷,one case exhibited mandibular canines in a favourable position

while two and half years later these teeth were found to be mesially inclined, and the unerupted

mandibular left canine had crossed the midline.

Etiology of the transmigration of canines:

A specific etiology of this anomaly is unknown, but traumatic factors, heredity, the long eruption path of canine tooth germs, premature loss of primary teeth, filling of this space by an adjacent tooth, disharmony of tooth-size, unfavorable alveolar arch length, and over length of crowns can be the causative factors. Odontomas are also suggested as a possible etiological factor. ¹⁸

Javid⁴ and Joshi and Shetye⁹ suggested that the cause of transmigration may be an abnormally strong eruption force, which drives the canine through the dense symphyses. They also noted that the conical shape of the tooth aids its passage through the bone.

Vichi and Franchi¹⁹ suggested that agenesis of the adjacent teeth, in particular the lateral incisor, may favor retention of the primary canine and that the excess of space in the dental arch may account for the absence of a correct guide for eruption. They observed proclination of the lower incisors, increased axial inclination of the unerupted canine, and an enlarged symphyseal cross-sectional area of the chin in nearly all their cases. They suggested that these factors could play an important role in the mechanism of transmigration. They further stated that the unerupted canine has the possibility of deviating from its normal developmental site, moving to a horizontal position, and migrating through the symphyseal bone only if enough space is available in front of the lower incisors.

Thoma⁸, Fiedler and Alling¹⁸, Greenberg and Orlian¹¹, and Wertz¹⁴ reported cases in which a radiolucent area resembling a cystic lesion surrounded the transmigrated canine. However, it is difficult to say whether these pathological conditions were responsible for the transmigration or whether the pathological condition occurred after the migration of the canine.

Al-Waheidi¹⁷ suggested that transmigrated canines are usually associated with a cystic lesion and that the presence of a cyst at the crown of the canine may facilitate the migration process.

The degree of inclination of canines to the midsaggital plane is also proposed by some authors. Howard¹² observed that those unerupted canines that lie between 25 ۫ and 30 ۫ in the midsagittal plane do not migrate across the mandibular midline. Those canines that lie between

30 ۫ and 95 ۫ tend to cross the midline. When the angle exceeds 50 ۫, crossing the midline becomes a rule.

Ando et al² suggested the premature loss of teeth, inadequate space, and excessively large crowns as etiological factors. However, premature extraction of the deciduous canine

is practiced in an attempt to correct the eruption of an ectopic permanent canine.

Costello et al²⁰ and Joshi⁹ noted several cases where the deciduous canine had been retained.

Several cases of transmigrated canines occurred in conjunction with hypodontia and excess space. The role of crowding and spacing in the etiology of ectopic canines is difficult to determine. However, transmigration has been reported to occur in both situations.

Joshi⁹ disagreed with the idea of lower incisor proclination and enlargement of the symphyses as etiologic factors. Kerr¹³ suggested that the increase in lower incisor proclination may be due to normal variations of incisor angulation during growth. Retention of primary canines does not seem to be an etiological factor and is more.

Treatment of transmigrated mandibular canines

There are several treatment options proposed for unerupted mandibular canines. Surgical extraction appears to be the most favored treatment for migrated canines, rather than a heroic effort to bring the tooth back to its original place. This is especially true when the mandibular arch is crowded and requires therapeutic extractions to correct the incisor crowding.¹ Thoma⁸ stated that transmigrated canines usually have to be removed.

Transplantation.

If the mandibular incisors are in a normal position and space for the transmigrated canine is sufficient, transplantation may be undertaken. Howard¹² transplanted a transmigrated canine when there was enough space to accommodate the tooth.

Exposure and orthodontic alignment.

Wertz¹⁴ used orthodontic treatment to bring a labially impacted transmigrated canine into position. However, if the crown of such a tooth migrates past the opposite incisor area or if the apex is seen to have migrated past the apex of the adjacent lateral incisor, it might be mechanically impossible to bring it into place. Abbott et al²¹ described the transposition of an incompletely erupted permanent right canine to a position between the permanent left canine and the left lateral incisor and indicated that the tooth was amenable to orthodontic treatment. They suggested that the premature extraction of first premolars should be avoided when radiographs demonstrate the presence of an overly mesially angulated unerupted canine that has begun to migrate labially across the incisors. In these cases, it may be impossible to bring the canine to its correct position. Taguchi et al²² reported considerable improvement in the position of those canines associated with an odontoma, after removal of the odontoma and surgical exposure.

Observation.

It has been advocated that an unerupted impacted tooth be removed as soon as convenient.¹³ Other authors²⁵, however, believe that symptomless, nonerupted teeth can be left in place. In these patients, a series of successive radiographs should be taken periodically. A progressive worsening of the position of the unerupted canine or suggestion of cystic change of the follicle should lead the clinician to consider the possibility of surgical extraction. The existence of pressure resorption of the roots of adjacent teeth, periodontal disturbances, or other possible foci for the spread of infection, prosthetic problems, malposition of the adjacent teeth, and neuralgic symptoms have been included as indications for surgical intervention in cases of impacted mandibular canines.³

Conclusion:

Transmigration of the mandibular canine is a rare event. Its association with other inherited dental anomalies points to a genetic etiology, with a defect in the dental follicle metabolism ‘‘misdirecting’’ the eruption path from the normal vertical pattern to a mesial and apical pathway. Treatment is complicated and rarely leads to an ideal result.

References:

1.      Camilleri S, Scerri E. Transmigration of mandibular canines – A review of the literature and a report of five cases. Angle Orthod;73:753-62,2003

2.      Ando S, Aizawa K, Nakashima T, Sanka Y, Shimbo K, Kiyokawa K. Transmigration process of the impacted mandibular cuspid. J Nihon Univ Sch Dent;6:66–71,1996.

3.      Tarsitano JJ, Wooten JW, Burditt JT. Transmigration of nonerupted mandibular canines: report of cases. J Am Dent Assoc;82:1395–1397,1971.

4.      Javid B. Transmigration of impacted mandibular cuspids. Int J Oral Surg;14:547–  549,1985.

5.      Rebellato J, Schabel B. Treatment of patient with an impacted transmigrant mandibular canine & a palatally impacted maxillary canine. Angle Orthod;73(3):328-36,2002.

6.      Shah RM, Boyd MA, Vakil TF. Studies of permanent tooth anomalies in 7,886 Canadian individuals. I: impacted teeth. J Can Dent Assoc;44:262–264,1978.

7.      Grover PS, Lorton L. The incidence of unerupted permanent teeth and related clinical cases. Oral Surg Oral Med Oral Pathol; 59:420–425,1985.

8.      Thoma KH. Oral Surgery. 2nd ed. St Louis, Miss: CV Mosby; 1952

9.      Joshi MR, Shetye SB. Transmigration of mandibular canines: a review of the literature and report of two cases. Quintessence Int;25:291–294,1994.

10.  Nodine AM. Aberrant teeth, their history, causes and treatment. Dent Items Interest;65:440–451,1943.

11.  Greenberg SN, Orlian AI. Ectopic movement of an unerupted mandibular canine. J Am Dent Assoc;93:125–128,1976.

12.  Howard RD. The anomalous mandibular canine. Br J Orthod;3:117–121,1976.

13.  Kerr WJ. A migratory mandibular canine. Br J Orthod;9: 111–112,1982.

14.  Wertz RA. Treatment of transmigrated mandibular canines. Am J Orthod Dentofacial Orthop;106:419–427,1994.

15.  Mupparapu M. Patterns of intra-osseous transmigration and ectopic eruption of mandibular canines: review of literature and report of nine additional cases. Dentomaxillofac Radiol;31:355-60,2002.

16.  Howard RD. The anomalous mandibular canine. Br J Orthod;3:117-21,1976.

17.  Al-Waheidi EM. Transmigration of unerupted mandibular canines: a literature review and a report of five cases. Quintessence Int.;27:27–31,1996.

18.  Fiedler LD, Alling CC. Malpositioned mandibular right canine: report of case. J Oral Sur.;26:405–407,1968.

19.  Vichi M, Franchi L. The transmigration of the permanent lower canine. Minerva Stomatol;40:579–589,1991.

20.  Costello JP, Worth JC, Jones AG. Transmigration of permanent mandibular canines. Br Dent J.;181:212–213,1996.

21.  Abbott DM, Svirsky JA, Yarborough BH. Transposition of the permanent mandibular canine. Oral Surg Oral Med Oral Pathol;49:97,1980.

22.  Taguchi Y, Kurol J, Kobayashi H, Noda T. Eruption disturbances of mandibular permanent canines in Japanese children. Int J Paediatr Dent.;11:98–102,2001.

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