ÖZET ABSTRACT

Transmigrasyon, daimi kanin dişlerine özgü, üst çene-ye göre daha çok alt çenede görülen ender rastlanan bir anomalidir. Bu makalede, altı vaka takdimi yanısı-ra, konu ile ilgili klinik ve radyolojik özelliklere değinil-mektedir. Literatürde transmigre kaninlerle ilgili yeni bilgiler yer alsa da oluşma mekanizması hakkında-ki tartışmalar devam etmektedir. Transmigre kaninle-rin erken dönemde teşhis edilmesi, tedavi planlaması ve komplikasyonların ortaya çıkması açısından önem taşımaktadır. Bu dişlerin sürme yolu boyunca komşu dişlerde oluşturabileceği zararı engellemek amacı ile operatif çekimleri düşünülmelidir. Buna rağmen, asemptomatik transmigre kaninlerin operatif olarak çekimleri yerine, periyodik olarak klinik ve radyolojik takibe alınmaları düşünülebilir.

Dental transmigration is an infrequent eruptive disor-der and it develops exclusively in mandibular canines while maxillary canines are rarely involved. Six cases of this rare dental anomaly are presented and discus-sed with clinical and radiological characteristics in this case series. Although new findings about transmigra-tion of maxillary and mandibular canines are reported in the literature, controversy over the etiology conti-nues. Early detection of a transmigrant tooth is essen-tial for the treatment, planning and prevention of more complicated situations. The surgical removal of the tooth should be considered to prevent the possible damage to the numerous teeth developing along the path of migration. However, the surgical removal of an asymptomatic transmigrated tooth may be limited to periodic clinical and radiological follow-up visits.

Hacettepe Diş Hekimliği Fakültesi DergisiCilt: 34, Sayı: 1-2, Sayfa: 23 -29, 2010

Transmigration of Impacted Canines: Six Case Reports

Gömük Kanin Dişlerde Transmigrasyon: 6 Olgu Sunumu

* Banu ÖzveRi KoyunCu DDS, PhD, * erdoğan ÇeTingül DDS, PhD* University of Ege, Faculty of Dentistry, Department of Maxillofacial Surgery

OLGU RAPORU (Case Report)

ANAHTAR KELİMELERGömük diş, kanin, transmigrasyon.

KEYWORDSImpacted tooth, canine, transmigration

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INTRODUCTION

Migration of a canine from its normal position to the contralateral hemiarch, crossing the mid-line is known as transmigration. This phenome-non is a rare, unusual developmental anomaly of unknown origin and it occurs almost exclusively with mandibular canines1-8 but also develops ra-rely in maxillary canines as well. This condition was first reported by Aydin and Yılmaz3 in 2003. In a review of 4,500 panoramic radiographs, Ay-din et al.6 identified eight mandibular canines and six maxillary canines (0.31 %). Aras et al.9 also re-ported 12 cases of transmigrant maxillary cani-nes in a sample of 6000 individuals.

This anomaly is most often asymptoma-tic, with no pain or over pathology, and usually cannot be detected during a clinical examinati-on. Mandibular transmigration is rarely discove-red on a routine periapical radiograph because the tooth is most frequently horizontally impac-ted under the apices of the permanent teeth ad-jacent to the mandibular border. Similarly, a pa-latally impacted canine is sometimes horizontally positioned very high in the palatal vault, close to the floor of the nasal cavity and thus might not be detected on a routine periapical radiog-raph. Therefore, when any permanent tooth is clinically missing, a panoramic radiographic exa-mination is essential10.Transmigrating teeth can cause pressure, resorption of roots or tilting of adjacent teeth11,12 and neuralgic symptoms12 cau-sing pain and discomfort in the patient.

Our Pubmed search revealed only five publis-hed articles that described maxillary canine mig-ration to the contralateral side 3,6,9,10,13. The aim of this case series report was to describe the cli-nical and radiological characteristics of 6 additio-nal cases of transmigrant canines, two of which are in the maxilla and four in the mandible.

Case 1

A 52-year-old female was referred for the construction of a prosthesis to a dental practi-tioner. It was observed by the dentist in the pa-noramic radiograph that the mandibular left ca-nine was impacted. Then the patient applied to

Ege University School of Dentistry, Department of Oral and Maxillofacial Surgery for the remo-val of this tooth. Intraoral examination showed that there was a swelling at the fornix vestibulum of the anterior portion of the mandible. Radiolo-gical examination revealed that the canine was impacted mesioangularly with part of the crown crossing the midline. The crown of the tooth was surrounded by a follicular cyst (Figure 1).

Case 2

An 18-year-old female was presented to our department with a complaint of moderate pain in the right third molar region of the mandible. The panoramic radiograph revealed all the third mo-lars were impacted and were covered with muco-sa. Both of the maxillary canines were also une-rupted. The right maxillary canine was impac-ted mesioangularily and the left maxillary cani-ne was impacted horizontally. Tooth 53 was mis-sing. The left maxillary canine had migrated ac-ross the midline located below the apices of the incisors and showed no evidence of resorption or pericoronal radiographic changes suggesti-ve of cystic degeneration (Figure 2). Adjacent te-eth appeared normal. Tooth 63 did not show any signs of physiological resorption. The patient was asymptomatic and was informed of the condition.

Case 3

A 15-year-old male was presented to our de-partment with a complaint of painless modera-te swelling in the left canine region of the man-dible. Oral examination revealed that left mandi-bular canine was missing in the dental arch and there was a swelling at the fornix vestibulum of the left canine region. Tooth 72 and 73 were in the dental arch. Panoramic radiograph showed transmigration of the mandibular left canine as-sociated with a radiopacity compatible with an odontoma (Figure 3).

Case 4

A 39-year-old male was presented to our cli-nic with pain in the right maxillary premolar re-gion. Clinical examination showed that there was a swelling at the fornix vestibulum of the

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premolar teeth. Extraorally, the right sulcus na-solabialis had become indistinct. For the radiolo-gical evaluation, a panoramic radiograph was ta-ken. It depicted a transmigrated impacted cani-ne tooth with a supernumerary tooth which were surrounded by a follicular cyst (Figure 4). Follicu-lar cyst was extending from the maxillary right incisive tooth to the maxillary right first molar tooth.

Case 5

A 12-year-old male was presented to our cli-nic with pain in the right mandibulary canine re-gion. Oral examination revealed that right man-dibular canine was missing in the dental arch. Tooth 83 was in the dental arch. The panora-mic radiograph and 3D computed tomography revealed that the right mandibulary canine had migrated to left side crossing the midline below the apices of the incisors, and showed perico-ronal radiographic changes suggestive of cystic degeneration (Figure 5 and 6). Surgical removal of the transmigrated canine was advised to the patient’s family. Standart intraoral approach was used for surgical extraction (Figure 7).

Case 6

A 23-year-old female complained about her left mandibular first molar region. The panora-mic radiograph revealed that the right mandi-bulary canine had migrated across the midline. The left maxillary canine had also migrated ac-ross the midline located below the apices of the incisors and showed no evidence of resorption or pericoronal radiographic changes suggestive of cystic degeneration. Adjacent teeth appeared normal (Figure 8). The patient was asymptoma-tic and was informed of the condition.

DISCUSSION

Canine impaction is more prevalent in the maxilla than in the mandible, but canine trans-migration is more frequent in the mandible. The larger cross-sectional area of the anterior man-dible compared with the anterior maxilla may be a reason for the higher frequency of mandibular

FIGURE 1

Panoramic radiograph showing transmigrated canine surrounded by a dentigerous cyst.

FIGURE 2

Asymptomatic transmigrated canine in the maxilla.

FIGURE 3

Panoramic radiograph showing transmigrated canine associated with odontoma.

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FIGURE 4

Transmigrated maxillary right canine impacted with supernumerary tooth.

FIGURE 5

Transmigrated mandibulary canine surrounded by a dentigerous cyst.

FIGURE 6

3D CT showing transmigrated canine.

FIGURE 7

Surgical removal of the transmigrated canine.

FIGURE 8

Asymptomatic transmigrated mandibulary canine.

canine transmigration6. Rarity of transmigration of an impacted maxillary canine may be due to the negligible distance between the apexes of the maxillary canines and the floor of the nasal fos-sae, and to the presence of the midpalatal sutu-re, which is a considerable barrier against maxil-lary canine migration11 .

The etiology of transmigration is unknown; however, abnormal displacement of the tooth bud or deviation during development is the most com-monly accepted explanation5. However, heredity, multifactorial genetic factors,14,15 the long errupti-on path of canine tooth germs, premature loss of primary teeth and occupation of this space by an adjacent tooth, discrepancies in tooth-size, unfa-vourable alveolar arch length, and over length of crowns, odontomas, cysts and traumatic factors

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which lead to displacement of tooth buds can also be the causative factors2,4,12,16 .

Alaejeos-Algarra et al.12 stated that canine to-oth germs were located further from the normal site of eruption than were the germs of other te-eth. Although this is true for maxillary canines, it is not valid for the mandible. An anomalous position of the tooth germ may also be involved in the pathogenesis of canine transmigration17.

However, all available evidence points to the to-oth bud developing in its normal place and sub-sequently migrating to an ectopic position.

Joshi2 reported that trauma to the mandible at a very early age of the patient, and a very small obstacle, such as root fragment, could be sufficient to divert such a tooth to an abnormal path. Mitc-hell18 noted that traumatic fracture of the mandib-le near the site of the mandibular canine was ob-served in one 7-year-old patient as a causative fac-tor leading to the transmigration of the mandi-bular permanent canine. However, in the patient group of another study19 on impacted mandibular canines, only one patient had a history of trauma when he was eight years old but these authors do not think that trauma can be an etiological factor for impaction of teeth. In our case series, none of the patients had a history of trauma.

Sumer et al.20 reported that a permanent ca-nine within a dentigerous cyst might transmigra-te due to the cystic pressure. Although in one of their patients, the transmigrated canine was as-sociated with a dentigerous cyst, these authors thought that it might not be possible to determi-ne whether the tooth had transmigrated before the pathological process developed or not. Jos-hi2 also reported that it was difficult to unders-tand whether these pathologies were responsib-le for the transmigration process or the patholo-gical situations having occurred after the migra-tion of the canine. In our cases 1, 4 and 5 trans-migrated canines were associated with dentige-rous cysts but we also think like these authors that it is difficult to determine when these canine teeth have transmigrated. On the other hand, in the second case, and the last case as the patients

were asymptomatic, surgical removal of the te-eth were postponed and the patients were kept on periodic recalls.

In 70% of the odontomas, pathological altera-tions are observed in the neighboring teeth such as devitalization, malformation, aplasia, malposi-tion and the remaining embedded21.In our case 3, an odontoma was present in the place of per-manent canine, therefore, it was possible to think that the canine had migrated due to the odonto-ma. This finding was in accordance with a previ-ous report by Aktan et al.22 who had also stated that a 16 year-old- girl’s right mandibular cani-ne was impacted, crossing the midline under the apices of the incisors due to a compound odon-toma in the original position of the right canine.

Gonzalez-Sanchez et al.23 identified two su-pernumerary teeth in two cases that may have been the cause of the canines’ change in orienta-tion. Our case 4 also involved a supernumerary tooth and we think like these authors that super-numerary tooth may be the cause of migration of the canine tooth.

Joshi’s study2 showed 70.8% overretained de-ciduous canines, and 29.2% had exfoliated in the mandibular arch. This observation shows that, in the absence of the developing permanent mandi-bular canine under the deciduous canine, the re-sorption process of the root of the deciduous ca-nine is rather slow. We think that, in our second, third and fifth cases deciduous canines were in the dental arch because of the transmigrated ca-nine teeth not being under the deciduous canines.

Transmigration of canines has been reported more frequently in females than males in the ra-tio 1.6:124. Aydin et al.6 reported that the inci-dence of transmigrated maxillary canines was the same in both sexes. Also in Aras’s study9 a total of 12 patients had transmigrant maxillary canines, at a ratio of 1M:1F. In this case series report, transmigration was observed in three fe-males and in three males.

The mandibular canines have been reported to transmigrate mesially, bypassing the incisors and crossing the midline to as far as the canine

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of the opposite side, both unilaterally and bila-terally7,13. All transmigrant maxillary canine ca-ses have been reported as unilaterally up to now. Concurrent with these previously reported fin-dings in literature, in all of our cases, canines also migrated unilaterally. In the second case, both of the maxillary canines were impacted but only the left canine transmigrated.

Several treatment options are available for the transmigrated canines, which include surgi-cal removal, transplantation, orthodontic inter-vention and periodic observation but surgical re-moval appears to be the most favored treatment for migrated canines4. In our first, fourth, and the fifth cases, because of the cyst formations around the transmigrated mandibular and maxil-lary canines, enucleation with surgical removal of these teeth were made.

If the mandibular incisors are in a normal posi-tion and space for the transmigrated canine is suf-ficient, transplantation may be undertaken4,25,26.Aras et al.9 reported that in one case, the trans-migrant canine was transplanted to the normal position because of the failure of the eruption for-ce. Another treatment option is correction by ort-hodontic movement of the horizontally impacted and transmigrated mandibular or maxillary ca-nines to their normal anatomic positions in the arch. Wertz27 repositioned a vestibularly impacted transmigrant canine in this way. However, if the crown of the transmigrated canine moves past the opposite incisor area or if the apex is seen to have migrated past the apex of the adjacent late-ral incisor, it might be mechanically impossible to bring the tooth back into the place. In such cases, extraction is preferred to prevent the possible da-mage to the numerous teeth developing along the path of migration2,28. If the patient is asymptoma-tic, the transmigrated canine can be left in pla-ce; however, regular follow-up with radiographs is essential to detect potential pathology associa-ted with the impacted canine2,3,4,29. On the other hand, the patient’s desire must be taken into con-sideration because the patient may insist on the surgical removal of the impacted canine tooth. In

our case 2 and 6, orthodontic movement of the transmigrated canine was impossible because of their positions. The patients were asymptoma-tic, the transmigrated canines were left in places, however, to prevent the long-term complications, the patients were recalled with 6-month intervals for radiographic controls. In case 3, the patient refused surgical treatment including extraction of the odontoma and transmigrated tooth.

CONCLUSIONS

Migration of the maxillary and mandibular canines through the midline is generally asym-ptomatic. Whenever the permanent canines are not observed in the oral cavity in the expected time scale, panoramic radiographic examinati-on is essential. Early diagnosis is important for the treatment planning and prevention of more complicated situations. Although new findings about transmigration of maxillary and mandibu-lar canines are reported in the literature, contro-versy over the etiology continues and questions on this topic still remain unresolved. Therefore, detailed mechanisms of the transmigration ori-gin is a subject of further researches.

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CORRESPONDING ADDRESS

Banu Özveri Koyuncu DDS, PhDUniversity of Ege, Faculty of Dentistry, Department of Maxillofacial Surgery, 35100-İzmir-Türkiye

Phone: 0-232-3881108 Faks : 0-232-3398289 E-mail: banuozverikoyuncu@yahoo.com

Geliş Tarihi : 25.11.2009 Received Date : 25 November 2009 Kabul Tarihi : 25.02.2010 Accepted Date : 25 February 2010