Orthodontics

Bilateral distal ectopic eruption of thepermanent mandibular centrai incisors: A case reportMaristeîa Barbosa Pórtela, DDS, MSDVAna Lucia Freiré Sanchez, DDS,Rogério Gleiser, DDS, MSD,

A 7-year-old female patient presented with a rare case of bilateral distal ectopic eruption ol the mandibularpermanent central incisors. Treatment instituted was extraction of the retained primary teeth and place-ment of a fixed appliance for alignment and repositioning of the mandibular permanent incisors,(Quintessence Int 2003:34:131-134)

Key words: children, ectopic eruption, HIV infection, mandibular central incisor

Dental eruption has been defined as the movementof a tooth from its original posifion of develop-

ment to its ftinctional position in the oral cavity.̂ Insome cases, deviations from the normal pattern oferuption may occur, leading to a change in the finalposition of the tooth, which is called ectopic eruption.^O'Meara' stated the most extreme case of ectopiceruption involves the eruption of the tooth into a posi-fion normally occupied by anotber tootb (dentai trans-position).

The prevalence of ectopic eruption of a permanenttooth associated witb résorption of the adjacent pri-mary tooth varies from 2% to 12°/i>, depending on thetooth involved.^ O'Meara^ observed in a study of 315cases of ectopic eruption involving central and lateralincisors and first permanent molars, a frequency of12% to 52%, where 33% of the cases corresponded to

'High Postgraduate Student, Department ot Microbiology (IMPPG),University of Brazil (UFRJ), Rio dB Janeiro, Brazil.

^Associate Professor, Department ot Pedralric Dentistry, Gama Filho

tJniversity, Rio de Janeiro, Brazil,

^Associate Protessor, Department of Orttiodonlics and Pédiatrie Dentisiry,University oí Brazil ¡UFRJ), Rio de Janeiro, Brazil.

Reprint requests: Dr Manstela Barbosa Pórtela, Rua Beberibe, 273/201,Ricardo de Albuquerque, Rio de Janeiro, RJ, CEP 21640-070, Brasil.E-mail: mbportela@ hotmail,com

ectopic eruption of the central incisor, withoutpredilection to sex or side, the right side being morefi^equently involved, mainly in tbe cases of the centralincisor.

The literature states some etiologic factors for ec-topic erupfion of lateral incisors: crowding, superntt-merary teeth and idiopathic causes,̂ as well as the pre-mature loss of the primary canine' and the prolongedretention of the corresponding primary teeth,*O'Meara,' who invesfigated ectopic eruption of cen-tral incisors, did not give an explanation for the etiol-ogy of such alteration.

Two types of treatments in cases of mandibular lat-eral incisor ectopic eruption have been proposed. Thefirst involves extraction of the relevant permanent lat-eral incisor and the corresponding retained primaryteeth. In cases of crowding, alignment of the remainingteeth is performed later' The second type of treatmentis extraction of the corresponding retained primarytooth and later afigmnent of the mandibular incisors.This strategy', once performed in the initial stages ofocclusion development, could provide enough spacefor the correct positioning of the permanent canines,''

The purpose of this article is to present a rare caseof bilateral distal ectopic erupfion of both mandibularpermanent central incisors, as well as the treatmentperformed before the erupfion of canines and first pre-molars, in order to minimize the collapse of the dentalarch in the anterior region.

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Porteia et al

Fig 1 In.tiai clinicai appearance. Fig 2 initial periapica, radiograph.

Fig 3 After extractions of primary ,.Ly..i,]l i;..;,ors. edgewisebrackets were placed on permanent incisors and primary ca-nines,

CASE HISTORY

A 7-year-old female patient at the Oral HealthPromotion Project for children infected with HIV inthe Department of Pédiatrie Dentistry at theUniversity of Brazil (UFRJ) was diagnosed during rou-tine clinical exam, witb an alteration in eruption pat-tern of tbe mandibular central incisors. These teetherupted distally to the corresponding primary teeth,which were nol normally exfoliated (Fig 1) and had nosigns of physiologic résorption (Fig 2),

The patient was at the early mixed dentition stage,the molars in Angle Class I position and the mandibu-lar primary canines in crossbite. Excess space waspresent in tbe mandibular arcb, and the primary in-cisors were slightly flared or proclined. The diagnosiswas ectopic eruption of the mandibular permanentcentral incisors, Tbe treatment objectives consisted ofextraction of the retained primary teeth first, followedby alignment of the permanent incisors.

Two weeks after extraction of the primary centralincisors, edgewise brackets were placed on tbe perma-nent incisors and primary canines, but not on the right

Fig 4 After 1 month of treatment, elastic chains were used tociose the diasiemas.

permanent lateral incisor, which was still erupting. Anorthodontic wire (Twist-flex [0,014 mm], Morelli) wasused for the initial leveling and alignment of the teeth(Fig 3). After fifteen days, it was replaced by a round0.014-mm stainless steel wire to improve alignment.After a montb, a 0.016-mm arcb wire was made andelastic chains were used to close tbe diastemas (Fig 4),Two months after beginning treatment, a normal incli-nation of the incisors and correction of the crossbiteof the primary canines were obtained (Figs 5 and 6),After the complete eruption of the right permanentlateral incisor, the fixed appliance was replaced with afixed lingual retainer, until eruption of the permanentcanines.

DISCUSSION

The permanent mandibular incisors normally developlingually to the corresponding primary teeth.^ Theirlingual eruption usually leads to nonexfoliation of theprimary teeth, a normal situation not requiring any in-tervention, since their anterior migration will occur by

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Fig 5 Fnal clinical appearance Fig 6 ^ '

tbe action of the tongue musculature, concurring withthe growth and development of the mandibular ante-ñor segment^ In the current study, this was not thepattern of eruption found, as tbe incisors showed adistal direction of eruption in relation to their corre-sponding primary teeth. This lead to the diagnosis ofectopic eruption, which was in agreement with thestudy by Scbaad and Thompson.'"

Tbe etiologic factors for this eruption alteration,specifically of lateral incisors, bave been cited by someauthors as crowding, supernumerary' teeth, idiopathiccause.- premature loss of the primary' canine,' and pro-longed retention of the corresponding primary teeth.^In the current case, ectopic eruption of the permanentcentral incisors was diagnosed, but crowding and thepresence of supernumerary teetb were not present, al-though slight spacing was found in tbe affected arch.This may be considered an important factor in the eti-ology since in the presence of excess space, teeth maylose their eruption guidance and could deviate fromthe roots of the primary teeth. Taylor and Hamilton's-study involving 16 cases of ectopic eruption of the lat-eral incisor also observed tbat in more tban half oftbeir sample, the affected dental arch had sufficientspace to accommodate all teeth.

Sweet' suggests that one of tbe factors responsiblefor the alteration in the eruption position of the lat-eral incisors couid be tbe premature loss of the pri-mary canine, leading to an eruption pattern with adistal orientation. Taylor and Hamilton^ disagree withthis suggestion, because in their sample the canineand the lateral primary incisor were rarely absent. Inthe current case there was not premature exfoliationof any primary tooth, probably due to the irregularaxial inclination of the teetb on tbe anterior segmentthat contributed to tbe positive discrepancy, enablingtbe eruption of the central incisors.

The prolonged retention of the corresponding pri-mary teetb was a condition present in the current casepatient. Rose*̂ pointed to this factor as the possiblecause of ectopic eruption, hut Taylor and Hamilton^considered it to be tbe result of the ectopic eruption ofits successor. Bradley and BelP concluded that it wasnot clear whether tbe prolonged retention of the pri-mary teeth is the result or the cause of the alterationof eruption pattern of the permanent successor. Theystated that the lack of a correct intraosseous position-ing of the teeth would not cause adequate pressure onthe primary' root to stimulate résorption. Thus delayedexfoliation would be a secondary' characteristic.

The treatment for this case of bilateral ectopic erup-tion of the mandibular central incisors was tbe extrac-tions of the primary teeth witb prolonged retentionfollowed by realignment and leveling of the mandibu-lar anterior segment. Tbis strategy is in agreement witbBradley and Bell.-' Tbey recomtnended correction inthe initial stages of the malocclusion, as it provides abetter chance for the correct positioning of the perma-nent canines and first premolars, and apart from fa-voring a good prognosis, also makes treatment fasterand easier.

CONCLUSION

In the presence of ectopic eruption of the mandibtilarcentral incisors, diagnosis and intervention in theearly mixed dentition is recommended. Orthodontictreatment performed before tbe eruption of tbe perma-nent canines may reduce tbe time and complexity' ofthe procedure, favoring an adequate development ofthe dentition.

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REFERENCES

1. Massler M, Schour I. Studies in tooth development;Theories of eruption. Am J Orthod 194t;27:552-556.

2. Taylor GS, Hamilton MC. Ectopic emptioti of iower lateraljnctsors.ASDCJ Dent Child 1971;38:282-284.

3. O'Meara WP. Ectopic eruption pattern in selected perma-nent teeth. J Dctit Res 1962;41:607-616.

4. Bradley E], Bell RA. Eruptive malpositioning of the man-dibular permanent laterai incisors: Three case reportsPediatr Dent 1990; 12:380-387.

5. Sweet CA. Ectopic eruption of permanent teeth. ) Am DentAssoc 1939:26:574-579,

6. Rose JS. Atypical paths of eruption: Some cases and effects.Dent Pract 1958;9:69-76.

7. Shapira Y, Kuftinec MM. The ectopically erupted mandihu-lar lateral incisor. Am J Orthod 1982;82:426-429.

8. Bennett N. The Science and Practice of Dental SurgeryOxford: Oxford University Press, t990. Apud in: Deery EThe relationship of crowding to the eruptive position of thelower permanent incisors. Br I Orthod 1993;20:333-337

9. Geliin ME, Haley JV. Managing cases of over-retenti on ofmandibular primary incisors where their permanent succes-sors erupt iingually. ASDC J Dent Child t982;49:l 18-122.

10. Schaad TD, Thompson HE. Extreme ectopic eruption of theiower permanent lateral incisor. Am J Orthod 1974;66:280-286.

134 Volume 34. Numbef 2, 2003

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