PEDIATRIC DENTISTRY/Copyright © 1989 byThe American Academy of Pediatric DentistryVolume 11, Number 2 Case Reports

Management of an early ankylosed mandibularsecond primary molar: case reportMilton E. Gellin, DDS Gerald A. Ferretti, DDS, MSD

Abstract

An unerupted mandibular second primary molar first wasobserved in a healthy male 3 years, 4 months of age. The reportpresents the rationale to allow the first permanent molar toerupt fully. The treatment objectives are presented with thedescription of the fixed appliances used to accomplish theobjectives.

Few case reports have discussed longitudinaltreatment of failure of eruption of a primary secondmolar during the primary and early mixed dentitions.This case report describes the long-term management ofan untreated ankylosed mandibular second primarymolar over a 9-year period.

Literature Review

Kurol and Thilander (1984) evaluated thelongitudinal effects of ankylosed primary molars firstobserved in the mixed dentition until normal exfoliationoccurred or treatment was indicated. The purpose ofthis investigation was to determine the effects ofinfraclusion on occlusal development. Fifty-six childrenwith 149 ankylosed primary molars were followed. Allbut 5 of the 149 teeth exfoliated normally with noresultant adverse effect on occlusal development. Fiveankylosed teeth were extracted. When the followingcriteria are present extraction is indicated: (1) Occlusaldisturbances with severe tipping of adjacent teeth andresultant space loss; and (2) malposition of thepermanent successor with severe infraclusion andirregular root resorption of the ankylosed molar.

Adams et al. (1981) described a mandibular secondprimary molar in a 5 year old that was not visibleclinically but had a clinically visible orifice about 3 mmin diameter. All succedaneous teeth were present.Surgical removal of the unerupted second primarymolar was performed and a distal shoe spacemaintainer was inserted. No subsequent observationsor further treatment were reported.

Amir and Duperon (1982) described a five year old

with an unerupted mandibular second primary molarand a malformed, developing second premolar. Adecision was made to remove the unerupted secondprimary molar. At a 6-month follow-up examination thedeveloping second premolar appeared as an odontoma,but no further observations or treatment were reported.

Marechaux (1986) reported that a 7 year old had unerupted mandibular left second primary molar witha small supernumerary tooth-like formation at the crestof the alveolar bone. The permanent first molars wereunerupted. The patient was observed for a 3-year periodand received the following care: (1) removal of theankylosed primary molar; (2) insertion of a sectionalspace maintainer from the first primary molar to thenow erupted permanent first molar; and (3) removal the unilateral space maintainer after 6 1/2 months andthe insertion of a lingual arch. In spite of thesetreatments, the space for the unerupted secondpremolar closed to 3 mm. Space regaining procedureswere indicated at age 10. No further treatment wasreported.

In the preceding case reports the unerupted man-dibular second primary molars were not visibleclinically.

These reports contrast with Belanger et al. (1986)who described an unusual case of a 3 year old with anunerupted mandibular second primary molar. Whenthe child returned 9 months later cusp tips were visibleclinically. No treatment of the ankylosed tooth wasperformed because upon percussion the sound wassimilar to the contralateral primary molar. For the next3 years and 9 months, periodic visits revealed that theankylosed primary molar had self-corrected and was inthe plane of occlusion.

Case ReportA healthy 3-year, 4-month-old Caucasian male was

seen for oral evaluation. An unerupted mandibular leftsecond primary molar was noted on the panoramic

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Fie 1. Initial examination at 3 years, 4 months. Mandibular leftsecond primary molar unerupted. All succedaneous teethpresent.

FIG 2. Six years, 1 month. Note unerupted left primary secondmolar.

radiograph (Fig 1). This report discusses only treatmentof the ankylosed second primary molar. A decision wasmade to allow the mandibular left first permanentmolar and the mandibular permanent incisors to eruptat which time the left permanent first molar would beuprighted if needed and distalized by a fixed appliance.After the permanent first molar was repositioned theunerupted second primary molar would be extractedand an appropriate space maintainer placed.Continuous follow-up evaluations were done every 6months.

Diagnostic casts, and panoramic and cephalometricradiographs were completed at 6 years, 9 months. Thediagnostic casts revealed an acceptable alignment of theteeth. The maxillary and mandibular permanent lateralincisors were unerupted and the mandibular left firstpermanent molar was partially erupted and mesiallytipped causing space closure. When the mesiodistalmeasurement of the right mandibular second primarymolar (9.6 mm) was compared to the space between theleft first primary molar and first permanent molar therewas a 3.5 mm difference. No cross-bites were noted inthe transverse plane of space. In the anteroposteriorrelationships, the right first permanent molars wereend-to-end and a Class III molar relationship existed onthe left. The primary canines were end-to-end.

Radiographically, the ankylosed mandibular secondprimary molar was unerupted (Fig 2). The mandibularleft second premolar was rotated and distally inclined.

A cephalogram revealed that the maxilla andmandible were related well to the cranium and witheach other. The teeth related well to the maxilla and themandible, and the maxillary and mandibular incisors toeach other. Relationships in the vertical plane of spacewere acceptable for this age.

Treatment to distalize the mesially tippedmandibular left first permanent molar would beginwhen the mandibular permanent lateral incisorserupted. This occurred 1 year and 2 months later (8years, 1 month of age).

Treatment ObjectivesTreatment was confined to the mandibular arch. The

mandibular left first permanent molar was to beuprighted and distalized to allow greater access for theeventual removal of the ankylosed tooth. Thesemovements were to be accomplished with a series ofleveling round arch wires (up to a .018) and then an opencoil inserted to further translate the first permanentmolar. With insertion of the open coil the midlineswould need to be maintained. After distalization theankylosed second primary molar would be removedsurgically. The bands were to remain but the wire wasremoved during the surgical procedure and then retiedafter the procedure was completed to allow for healing.Final insertion of a space maintainer would preventrelapse of the now distally positioned first permanentmolar.

Space RegainingThe first permanent molars were banded with

preattached .022 x .028 buccal tubes with gingivalhooks. Mandibular premolar bands with weldedSiamese brackets (.022 x .028) were adapted to theprimary first molars. Brackets were direct bonded to themandibular incisors with Ormco System 1+® (OrmcoCorporation; Glendora, CA).

The initial wire was .0175 Wildcat8 (GAC In-ternational; Central Islit, NY) stopped arch wire. Thiswire (bent gingivally at the distal of the buccal tube) wasused to preserve the axial inclination of the mandibularpermanent incisors. Three weeks later a .016 stoppedarch wire was inserted. To maintain tooth position asingle ligature wire was twisted and tied to all bracketsbetween the first primary molars. Five weeks later astopped .018 arch wire was inserted for further levelingof the first permanent molar. The wire was removed 3weeks later. The stop was removed and the wire wasreinserted through the buccal tube of the left firstpermanent molar to allow for translation. An open coil(.009 x .030) was placed on the arch wire before it wasretied. The amount of activation was determined by the

142 EARLY ANKYLOSED MANDIBULAR SECOND PRIMARY MOLAR—CASE REPORT: Gellin and Ferretti

Fie 3. Total treatment time 4 months. Note split crimpable stopson .018 arch wire.

length of the coil as measured from the mesial of thebuccal tube on the first permanent molar to themidpoint of the bracket of the primary first molar. Topreserve the midline a single ligature wire was twistedand tied to all brackets between the first primary molars.Further activation of the coil took 2 visits at 3-weekintervals. Reactivation is accomplished by firstcompressing the coil and then compressing a splitcrimpable stop onto the arch wire. Total treatment timewas 4 months (Fig 3).

Surgical Removal of the AnkylosedPrimary Molar

Under IV sedation (5 months afterinitiating orthodontic treatment), theankylosed tooth was removed surgicallywithout difficulty. The arch wire was thenretied after suture placement. Within 1 weekthe sutures loosened and were removed,lodoform gauze was placed into the socketand repacked 3 times at 5-day intervals andthen removed. The surgical wound washealing as expected. Four months later themesiodens was removed under IV sedationwithout complication after radiographsconfirmed that the apices of the eruptedpermanent maxillary central incisors wereclosed.

Immediate Segmental Space MaintainerAfter the surgical site of the ankylosed

primary molar had healed, the bands andbrackets on all teeth except the left firstprimary and first permanent molars wereremoved. An immediate temporarysegmental space maintainer was placed. A

.020 wire was adapted to fit passively into the bracketand the buccal tube was tied to the bracket. A waitingperiod for further treatment decisions was planned dueto behavioral management problems.

Insertion of Lingual ArchAs anticipated, the immediate segmental space

maintainer inserted 5 months previously needed to bereplaced with a lingual arch before the first primarymolar exfoliated. The first permanent molar band wasremoved and new bands were adapted with a weldedWilson vertical post. After the impression was made,the first permanent molar band was recemented and thesegmented wire retied to prevent relapse until thelingual arch could be inserted. This lingual arch wasremoved 14 months later.

A series of periapical radiographs illustrate the 4treatment procedures used in this case report (Fig 4): (a)leveling arch wire; (b) open coil with split crimpablestops; (c) segmental space maintainer; and (d) Wilsonlingual arch. These radiographs also show that thedistally inclined second premolar uprighted butremained rotated. Photographs were made 2 years and4 months (12 1/2 years) after the lingual arch wasremoved. The treatment objective to regain the space forthe mandibular left second premolar was met (Fig 5,next page). It is anticipated that future comprehensivetreatment will be instituted to correct the Class IImalocclusion.

FIG 4. Summary of the 4 treatment procedures to distalize and maintain themandibular first permanent molar: (a) leveling arch wire; (b) open coil withsplit crimpable stops; (c) segmental space maintainer; and (d) lingual arch.Note the uprighting of the second premolar.

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FIG 5. Treatment objective met at 1 2 1/2 years.

DiscussionAn alternative approach to the treatment of this case

could have been the removal of the unerupted secondprimary molar at an early age since a tentative diagnosiswas made at 3 years, 4 months of age. Periodic recallvisits confirmed failure of eruption. Early removal of thesecond primary molar and the immediate insertion of adistal shoe space maintainer was considered.Contraindications to this approach were:

1. Surgical extraction for a young child is oftentraumatic and difficult, potentially requiring ageneral anesthetic

2. Damage to the developing second premolar mayoccur

3. Invasion of the crypt of the developing secondpremolar by the intraalveolar extension was possible

4. Accelerated root resorption of primary first molarused as an abutment could occur

5. The first permanent molar could tip mesially overthe distal extension

6. Other types of space maintainers would be requiredover the long term (Hicks 1973; Kapala 1980; Barker1982; Mathewson et al. 1982; McDonald et al. 1987).

The total time during which the appliances wereworn was approximately 2 years. The periodic, earlyobservation appointments helped to established arapport with the patient, allowing for surgical removalof the ankylosed primary molar.

Drs. Gellin and Ferretti are both professors, oral health practice,University of Kentucky Section of Pediatric Dentistry. Reprintrequests should be sent to: Dr. Milton E. Gellin, Dept, of Oral HealthPractice, Section of Pediatric Dentistry, University of Kentucky,College of Dentistry, D418, Lexington, KY 40536.

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Amir E, Duperon DE: Unerupted second primary molar. ASDC JDent Child 49:365-68, 1982.

Barber TK: Space management, in Pediatric Dentistry, Stewart RE,Barber TK, Troutman KC, Wei SHY, eds. St. Louis; CV Mosby Co,1982 p 345.

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McDonald RE, Hennon DK, Avery DR: Managing space problems,in Dentistry for the Child and Adolescent, 5th ed, McDonald RE,Avery DR, eds. St. Louis; CV Mosby Co, 1987 p 741.

Marechaux SC: The problems of treatment of early ankylosis: reportof a case. ASDC J Dent Child 53:63-66,1986.

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1982 p 642.

144 EARLY ANKYLOSED MANDIBULAR SECOND PRIMARY MOLAR—CASE REPORT: Gellin and Ferretti