Ectopic eruption of the maxillary central permanent

VOLUME 37 • NUMBER 9 • OCTOBER 2006 677

QUINTESSENCE INTERNATIONAL

Tooth eruption is the axial movement of a

tooth through an alveolar process, from its

intraosseous development position to occlu-

sion with the opposing tooth.1 During this

phase various disturbances can occur,

among them ectopic eruption, which is

defined as a deviation from the normal erup-

tion pattern, making the tooth erupt out of

position,1–6 and possibly causing resorption

of adjacent primary teeth.4,6–13

According to the degree of resorption,

these teeth may exfoliate precociously or be

indicated for extraction, with or without the

presence of painful symptoms.2

Ectopic eruption may be reversible or irre-

versible. In the first case, it is resolved sponta-

neously when the tooth erupts in its normal

position. In the second case, the tooth

remains retained until the precocious exfolia-

tion of the primary tooth involved or treatment

is begun.2,3,6,7,10–12,14,15 In the literature, the preva-

lence of ectopic eruption of maxillary perma-

nent first molars varies from 3.1%16 to 4.3%.2

Of these eruptions, 59% are reversible and

41% are irreversible.2 In individuals with a cleft

lip and/or palate, the prevalence of ectopic

eruption increases to around 20.0%17 to

21.8%.8 For the mandibular permanent first

molars, the occurrence is more rare,4,14,18 as for

the maxillary permanent central incisors.

There is no consensus about which sex is

most affected,10,16 as some authors indicate

females,1,8 and others males.2,6

Ectopic eruption of the maxillary central permanent incisors and mandibular first permanent molars: Report of an unusual caseLuciana Pomarico, DDS, MSD1/

Laura Guimarães Primo, DDS, MSD, PhD2/Denise Noce, DDS3

Ectopic eruption is a disturbance in which the tooth does not follow its usual course.

Among its more important etiologic factors are macrodontism, shortened arch length, pos-

terior positioning of the maxilla, atypical eruption angle, and genetic factors. This article

reports a rare case of ectopic eruption of 4 permanent teeth, maxillary central incisors and

mandibular first molars, in a child aged 7 years and 11 months, in which the treatment

consisted of extracting the maxillary primary central incisors and making an orthodontic

intervention on the mandibular arch. A bilateral fixed appliance containing 2 hooks with

loops, 1 buccal and the other lingual, was placed on the mandibular primary first molars.

The hooks were activated in a niche made of light-curing resin on the occlusal surface of

the mandibular permanent molars, to bring about the distal drift of these teeth. After 6

months, complete eruption of the mandibular permanent molars occurred, and a slight

displacement of the maxillary permanent central incisors toward the median line was

noted. The importance of early, adequate treatment is discussed. (Quintessence Int

2006;37:677–683)

Key words: tooth eruption, ectopic; orthodontics, interceptive; dentition, permanent;

molar; incisor; pediatric dentistry

1Assistant Professor of Pediatric Dentistry, Veiga de Almeida

University, Rio de Janeiro, Brazil.

2Associate Professor, Department of Pediatric Dentistry and

Orthodontics, Federal University of Rio de Janeiro, School of

Dentistry, Rio de Janeiro, Brazil.

3Pedodontist and Orthodontist, Department of Pediatric

Dentistry and Orthodontics, Federal University of Rio de

Janeiro, School of Dentistry, Rio de Janeiro, Brazil.

Reprint requests: Dr Luciana Pomarico, Praia do Flamengo

370/202 – Flamengo, 22210-030 Rio de Janeiro, RJ, Brazil. Fax:

55 (21) 2551-4354. E-mail: [email protected]

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678 VOLUME 37 • NUMBER 9 • OCTOBER 2006


Pomar ico et a l

Concerning localization, there is no differ-

ence regarding distribution per hemiarch2,16

nor whether it is unilateral or bilateral.2,10 Its

etiology is associated with macrodontism,

shortened arch length,1,7,13,16,19 posterior posi-

tioning of the maxilla,1,13,16,20 atypical eruption

angle,1,7,13,16 retarded calcification of some

affected permanent molars,16 familial tenden-

cies,6,8,21 and genetic factors.8

This article describes a rare case of

ectopic eruption of maxillary permanent cen-

tral incisors and mandibular permanent first

molars as well as the treatment given.

CASE REPORT

A male patient, aged 7 years and 11 months,

was referred to the pediatric dentistry clinic

of a public university by his dentist, with a

chiefly esthetic complaint about bad posi-

tioning of his anterior teeth. His medical his-

tory did not reveal anything noteworthy.

The clinical examination showed caries

lesions only on the mesial and buccal surfaces

of the maxillary primary central incisors, which

was confirmed by analysis of panoramic and

periapical radiographs. It was also found that

the patient had a Class III malocclusion, with

anterior mandibular tooth crowding of 3.0 mm.

The maxillary primary central incisors, which

were still in place, showed little root resorption.

The maxillary permanent central incisors had

erupted outside their axis, in the region of the

maxillary permanent lateral incisors and

through the palatine, causing exfoliation of the

maxillary primary lateral incisors (Figs 1a to

1d). The mandibular permanent first molars

had also erupted ectopically, suggesting that

the ectopic eruption was causing an initial

resorption of the distal root of the mandibular

right primary second molar (Figs 2a and 2b).

Additionally, it was noted that the mandibular

right permanent first molar showed hypoplasia

on its buccal surface.

A dental cast was made and, after exam-

ining the mixed dentition using the Moyers

method, a negative discrepancy of 11.6 mm

was found in the maxillary arch and 3.2 mm

in the mandibular arch. Although the

patient’s oral hygiene was good, biofilm had

accumulated in the region of the mandibular

permanent first molars.

The treatment plan consisted of extracting

the maxillary primary central incisors and

making an appliance to correct the ectopic

eruption of the mandibular permanent first

molars. The appliance was cemented on the

mandibular primary first molars; it contained

two hooks with loops, one buccal and the

other lingual, that were activated in a niche

made of light-curing resin tag on the occlusal

surface of the mandibular permanent first

molars. Three weeks later, a slight displace-

ment of the permanent central incisors

toward the median line (Fig 3a) was noted. To

separate the mandibular primary molars,

elastic bands were inserted for 2 days (Fig

3b) so that the appliance could be cemented

bilaterally (Fig 3c). After cementation, the

patient returned each week to control

hygiene, monitor the mesial drift of the maxil-

lary permanent central incisors, and to acti-

vate the mandibular appliance.

Clinical and radiographic examination at 3

months confirmed the disimpaction of the

mandibular left permanent first molar and of

the mandibular right permanent first molar at

4 months. After correction, retention was

maintained for 1 month between the

mandibular primary second molars and the

permanent first molars, to avoid mesial tip-

ping (Fig 4a); it was later exchanged for elas-

tic bands. The patient was kept under obser-

vation at appointments every 2 weeks until

complete eruption of the mandibular perma-

nent molars, which occurred after 6 months

(Figs 4b to 4e). The patient was then sent for

orthodontic evaluation and subsequent cor-

rection of his malocclusion at a suitable age.

DISCUSSION

Of the etiologic factors mentioned, the short-

ened arch length was present in the case

reported above. The patient showed irre-

versible ectopic eruption of the maxillary per-

manent central incisors and of the mandibu-

lar permanent first molars, as well as hypo-

plasia. This simultaneous occurrence was

also reported by Pulver,16 who found associa-




Pomar ico et a l

Fig 1a Intraoral situation of patient at 7 years and 11months.

Fig 1b Maxillary arch.

Fig 1c Panoramic radiograph of patient at 7 years and 6months, showing ectopic eruption of the maxillary perma-nent central incisors and mandibular permanent firstmolars.

Fig 1d Periapical radiograph ofthe maxillary anterior region.

Fig 2a Left bitewing radiograph. Fig 2b Right bitewing radiograph.



Pomar ico et a l

tion of ectopic eruption with other develop-

mental anomalies, although not by Bjerklin et

al.3 The present report differs from the litera-

ture with regard to the permanent teeth most

commonly affected by this pathology, which

are the maxillary first molars, maxillary

canines, mandibular canines, maxillary sec-

ond premolars, and maxillary lateral incisors.1

Some authors reported that diagnosis

occurred after the patient was 7 years of

age,2,15,17 as it did in this report, in which the

patient was aged 7 years, 11 months.

Diagnosis can be made either clinically3,13 or

through bitewing or routine periapical radi-

ographs,3,13,15 as well as through report of neu-

ralgic pain in the impacted area.5,9,22 It is impor-

tant to point out that at 7 years, most ectopic

eruptions have resolved themselves without

treatment, and after that age, only some of the

impacted molars erupt spontaneously.2,17

At times it is difficult to diagnose ectopic

eruption as reversible or irreversible, particu-

larly in cases with moderate retention seen in

a radiographic examination. However, it is

important to differentiate the 2 types to avoid

unnecessary treatment.2 Roberts13 recom-

mends that treatment be started as soon as it

is noticed that the tooth will not erupt spon-

taneously. Otherwise, it may cause rotation of

the first molar, malocclusion,15 space defi-

ciency, mesial drift of the first molar,6,15 greater

resorption of the primary molar,6 reduction of

the arch perimeter, mandibular anterior tooth

crowding, and impaction of the premolar.17

In this case, treatment was initiated at the

earliest possible moment with the purpose of

minimizing future occlusion problems in the

patient, since he already had an abnormal

occlusion. This proposal is in accord with

Bjerklin et al,7 who affirm that in cases in


Fig 3a (top left) Displacement of maxillary permanentcentral incisors toward the median line.

Fig 3b (above) Placement of bilateral elastic bands. Thelight-curing resin tags have already been placed on theocclusal surface of the permanent first molars.

Fig 3c (left) Close-up view of the cemented and activatedappliance.




Pomar ico et a l

Fig 4e Panoramic radiograph of patient at 8 years and 6months, after complete eruption of the mandibular perma-nent first molars.

Fig 4a Mandibular permanent first molars after disim-paction, with placement of retention.

Fig 4b Mandibular arch showing complete eruption of the mandibularpermanent first molars.

Fig 4c Mandibular left permanent first molar after disim-paction and complete eruption.

Fig 4d Mandibular right permanent first molar after disimpaction andcomplete eruption.




Pomar ico et a l

which other malocclusion problems occur,

the plan for the correction of ectopia should

be part of the total orthodontic treatment. It is

interesting to note that Pulver,16 in his study,

verified a low prevalence of patients with

Class III malocclusions suffering from

ectopic eruption—like the patient in the pres-

ent report—in spite of these individuals hav-

ing shortened arch length and retroposi-

tioned maxilla, which are related to the etiol-

ogy of ectopic eruption. In some cases,

because of the positioning of the tooth,

cleaning of the area is difficult.2 In addition,

there is no self-cleaning zone, which may

give rise to a greater caries risk. This fact was

noted in the present report, in which a

greater accumulation of biofilm was detected

on the impacted first molars.

Ectopic eruption can be corrected in 2

ways, by interproximal separation13,23,24 or by

distal drift of the ectopic molar,5,13,24–26

depending upon the degree of impaction.24

Hirayama and Chow23 suggested the use of

elastic separators and steel wire, placed

between the affected tooth and its adjacent

neighbor. The treatment in this case consisted

of a fixed appliance with 2 loops soldered to a

band cemented on the mandibular primary

first molars and activated to a resin tag bond-

ed to the occlusal surface of the impacted

molar. These devices, however, should only

be used as a basis when there is sufficient

root structure to ensure stability, ie, when

there is little root resorption,24,26 as in the pres-

ent case. Otherwise it may cause pain, infec-

tion,24 a dentoalveolar abscess, and ankylo-

sis.22 Pulver and Croft26 used a similar device,

although the band was placed on the primary

second molar. Similar treatments have been

reported in the literature, with slight differ-

ences such as duration of treatment,5 arch

involved,24 and association with other thera-

pies such as hemisection of the primary molar

involved18 and extraction with orthodontic

treatment.14 It is important to stress that failure

to begin orthodontic treatment after extracting

the primary tooth may result in mesial drift of

the permanent molar, space loss, malocclu-

sion, and periodontal problems.12

The treatment period of the case

described was 3 to 4 months, although there

are reports in the literature of treatments last-

ing from 3 weeks27 to 6 months.23 In this

report, in addition to the tooth disimpaction

period, it was necessary to place elastic

bands to avoid mesial drift of the permanent

first molar until it had fully erupted. This fact

is in accordance with Lin,25 who also used

this method after disimpacting the first per-

manent molar. An important factor in the

treatment of this patient was that a fixed

appliance was used for which the patient’s

cooperation was not necessary.

Two further aspects should be empha-

sized. The first concerns the absence of pain

in the area during the treatment, which is rel-

evant particularly in view of the patient’s

young age. The second is the rapid solution

of the problem, which facilitated the cleans-

ing of the area, thus lessening the risk of

caries.

CONCLUSION

A meticulous clinical examination is impor-

tant, always accompanied by routine radi-

ographs, to detect the presence not only of

caries lesions, but also of developmental

anomalies. Although the prevalence of

ectopic eruption is not very high, particular-

ly of the irreversible type, this condition can

occur. Pediatric dentists should be pre-

pared to make a correct diagnosis and to

plan the most suitable treatment for each

patient to avoid any damage, such as the

resorption of the primary second molar. In

the case presented in this article, a simple

appliance was placed to correct the ectopy

of the permanent molars and to minimize

the occurrence of severe malocclusion in

the future, since this patient already had an

abnormal occlusion. As presented, this

method of correcting molar ectopy may be

considered efficient and easy to use and

can facilitate early treatment, leading to a

very satisfactory result.

Pomarico.qxd 8/11/06 9:21 AM 82



Pomar ico et a l

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Ectopic eruption of the maxillary central permanent

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