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U n i l a t e r a l  d e la y e d e ru p tio n  o f m a x illa ry p e rm a n e n t f ir s t

m o l a r s :  fo u r  c a s e r e p o r t sM i e k o T o m i z a w a . D D S . P h D   H i ro k o Y o n e m o c h i , D D S  M i s a k o K o h n o . D D S . P h D  Tadashi H o d a , D D S ,  P h D

Delayed eruption or impaction of permanent

teeth is one of the severe problems that can

occur during  the  mixed dentition period.

These conditions can occur in any permanent tooth,

but the incidence of delayed eruption of the perma-

nent first molars, especially maxillary permanent first

molars, is very low. Johnsen1 found only one case of

delayed emergence of a maxillary first molar as a re-

sult of local etiologic factors in a review of the  records

of  1032  young people ranging in age from 8 to  18

years. Dachi and HowelP examined 1685 sets of ra-

diographs at the University of Oregon  and found no

case of impacted permanent first molars. Grover and

Lorton3 found only one case of an unerupted maxil-

lary first molar in their survey of the panoramic ra-

diographs of 5000 Army recruits ranging from  17 to

26  years of age.  Kramer  and Williams4  examined

3745 panoramic radiographs of oral surgery patients,an d found three cases of an impacted  m andibular first

molar but no  impacted maxillary first molar cases.

Permanent first molars are known as the  key teeth

in occlusion, and it is very important that the delayed

permanent first molars be guided  to the correct posi-

tion  in the dental arch. We encountered  four cases of

unilateral delayed eruption of m axillary permanent first

molars at the Pedodontic Clinic of Niigata University

Dental Hospital. We diagnosed the patients as having de-

layed eruption  if either more than one year had elapsed

since the antimere had erupted  fully or it did not eruptat all. According to the research carried out by the Japa-

nese Society of Pedodontics in  1988,5 the mean  age at

die time of eruption of the maxillary permanent first

molars is 6 years 8 months ± 8 months fo r Japanese boys

]4  F i g 1 . C a s e 1 . P a n o r a m ic r a d io g r a p hs h o w i n g a  r a d i o l u c e n t a re a s u r r o u n d i n gth e  c r o w n o f t h e u n e r u p t ed m a x i ll a ryr ig h t p e r m a n e n t f ir s t m o l a r .

  F ig 2 . C a s e 1 . P h o to m ic r o g h a p h o f th ee x c i s e d  g i n g i v a  I H E , o r ig i n a l m a g . 5 0 x 1 .

T h e r e a r e n u m e ro u s s m a ll i s la n d o r

c o r d s  o f o d o n t o g e n ic e p i t h e l iu m  a m o n dt h e m e s e n c h y m a l fib r o u s tis s u e .

and 6 years 7 months ± 8 months for Japanese girls. Fen-

estration of the gingiva was performed surgically in each

patient  and  occlusal guidance  by traction  was used  fo r

one. This paper presents the clinical and histopathologi-

cal findings in these four cases of unilateral delayed erup-

tion of maxillary permanent  first molars.

C a s e   r e p o r tsC a s e l

A  7-year,  11-month-old Japanese  gir l  visited

our  clinic with  the  complaint  of  unerupted maxil-

lary  right permanent  f i rs t  molar.  T h e  maxillary

left permanent first molar had erupted at the age of 6

years,  4 months.  Intraoral  examination revealed  no

swelling or redness of the gingiva in the region of the

maxillary right permanent  first  molar.  The  extent

of root formation of the  maxillary first molars was

one-half  on the  unerupted right side  and  three-fourths  on the  left  side. Radiographs revealed a radi-

olucent area surrounding the crown of the unerupted

first molar (Fig 1). When the girl was 8 years old,  the

overlying gingiva was surgically excised  and the  thin

alveolar  bone which covered  the  mesial half of the

occlusal surface was also removed to expose the tooth.

The specimens were sent for pathological examination.

In  the submucosal layer, there were numerous small

islands or cords of odontogenic epithelium among  the

mesenchymal fibrous tissue (Fig 2). The pathologi-

cal diagnosis was am eloblastic fibroma. Five monthsafter fene-stration,the maxillary right permanent first

molar erupted spontaneously.

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C a s e  2

An 8-year, 3-month-old Japanese boy was diagnosed

as  having delayed eru ptio n of the  maxillary left  perma-

nent first m olar based on the panoramic radiograph ob-

tained  dur ing  a  dental check-up  at our  clinic.  The

contralateral counterp art had erupted at the age of 7 years,

7  months. There was no swelling or redness of the gin-

giva in the maxillary left first molar region. Radiographic

exam ination Fig 3) revealed that the impac ted m axillary

left  first  molar was  located near  the  left  maxillary sinus,

and there was a radiolucent area containing a small, ra-

diopaque m ass situated occlusal to the left first mo lar, pre-

venting eruption. The root development of the m axillary

perm anent first molars was one-fourth on the unerupted

left  side and three-fourths on the right side. The tooth

formation o f the  maxillary left  permanent second molar

adjacent to the affected first m olar was also delayed com -

pared  with  the antimere. On the normal right side, thetooth crown of the m axillary permanent second molar had

already calcified,  while on the  left  side the  calcification of

the tooth crown was at the initial stage. The gingiva over-

lying the left  permanent first molar was excised twice, first

when th e patient was 8 years, 5 months and then at 9 years,

1 month, and the specimens were sent for pathological ex-

amination. Microscopically, islands or cords of odontoge-

nic epithelium that resembled dental papillae were observed

amo ng the mesenchymal tissue Fig 4). A small mass of

calcified  tissue was identified as imm ature enamel m atrixcovered with enamel epithelium. The  pathological diag-

nosis was ameloblastic fibroma with tooth-like s tru ctu re.

After  the second operation, the unerupt-ed first molar

began  to erupt spontaneously.

C a s e  3

A girl  aged  10 years, 3  months  was  diagnosed with

delayed eruption of the right maxillary first molar. The

maxillary left  perm anent first molar had erupted when shewas 6 years, 2  months old,  but the  right first molar had

no t erupted until she was 9 years, 8 months old, at which

time the maxillary right perm anent first molar and second

premolar  had  begun  to  erupt together.  The  second  pre-

molar erupted  fully  but the first molar  did  not.  Radio-

graphic examination revealed nothing that wo uld prevent

the eruption Fig 5). When s he was  10 years, 3 months

old, the overlying gingiva of the right perm anent first m o-

lar was surgically excised and the occlusal surface  exposed.

After surgery, there was no  further eruption and orthodon-tic traction w as applied. At the age of 10 years, 10  months,

she showed  full  eruption  of the  maxillary right perm a-

nent first mo lar Fig 6). The excised gingiva was exam-

ined microscopically, and it showed hyperplastic myxoid

tissue of the subm ucosal layer. The  histopathological d i-

agnosis was m yxofibrous  tissue of the gingiva Fig 7).

C a s e  

A 7-year, 7-month-old girl was brought to o ur clinic

because of cross bite of the max illary right p erm anent

lateral incisor. The first  oral examination revealed thatth e  maxillary right per m anen t f i rs t molar  had  fully

F ig  3 . C a s e 2 . P a n o r am ic r a d i o g r a p hs h o w in g a r a d i o lu c e n t a r e a w i th a

s m a ll r a d io p a g u e m a s s o c c l u s a l to t h em a x i lla r y   Io n p e r m a n e n t f ir s t m o l a r.T h e  t o o t h fo r m a t io n o f t h e  m a x i ll a r yl e ft s e c o n d m o l a r a d j a c e n t to i t is a l s od e la y e d c o m p a r e d w i th t h e a n t im e re .

 

F ig  4 . C a s e 2 . Photomicrograph showingth e  o d o n t o g e n ic ep ithelial Islands  ( O E l inthe mesenchym al tissue which resemb ledental papillae (H E . Original nag . 2 5 x 1 .

F ig  5 . C a s e 3 . Periapical radiographs h o w i n g  the  unerupted m axillary rightpermanent first molar  (arrow .

F lg  6. C a s e 3. (Al Clinical intraora l views showing the absenc e of the maxillary r ight permanent first m olar at the age of 10 y r , 3m o .  (B ) Partial eruption during applied traction. (C l Full erup tion a t h e a g e o f 1 0 y r. 1 0 m o O m ir ro r image).

54   American Academy   ofPediarric  Dentistry Pediatric Dentistry  20:1 1998

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Author Year

Miller 1976

Age Sex Location Treatment

6yr, 6mo M mandible enucleation of the

Histology

ameloblastic fibro-

Grove? 1985

Goho 1987

Spratley 1988

Matsuyama1° 1991

lesion and impacted

first molar

12 y, 6 mo M maxilla curettage

12 y M maxilla curettage

28 y M maxilla surgical removalof

the odontoma and

impactedfirst molar

7yr F mandible surgical removalof

the overlyingsoft

tissue9y F mandible radical exposureof

the tooth

13yr, 2 mo M mandible enucleation of

the tumor

10yr, 6mo M mandible enucleation of

the tumor

9yr, 2mo M mandible enucleation of

the tumor

8yr, 8 mo F mandible enucleation of

the tumor

odontoma

ameloblastic ibro-

odontoma

ameloblastic ibro-

odontoma

odontoma

dense, fibrous

connective issue

ameloblastic fibro-

odontoma

complex odontoma

odontogenic fibroma

ameloblastic fibro-

dentinoma

eruptedbut the left one had not emerged. hepan-oramic adiograph,obtainedwhen he was8 years, 1month ld, showedhat the root formation f the leftfirst molarwas n the beginningtage and hat on heright side wasone-third.The ooth developmentf theneighboring axillaryeft secondmolarwasalso delayedcompared ith hat of the right molar Fig.8). We b-served he left first molar or 9 monthsndwhenhe

was8 years, 10 months ld she wasdiagnoseds hav-ing delayed ruption f the maxillaryeft first molar.Theoverlying ingivawas urgicallyexcised.The irstmolar tarted to erupt 1 monthfter the excision.Mi-croscopic xaminationevealedmmatureollagen ibersirregularly istributedn the myxoidissueunderhe hy-perplasticmucosalpithelium,s wellas odontogenicpi-thelial islands(Fig 9). The athological iagnosiswasmyxofibrousissue of the gingiva.

 is ussion

There re systemic nd ocal factors that influence

delayed eruption of permanent irst molars. Thesystemicactors6 include familial endencyo retar-dationof eruption nd metabolic r endocrine istur-bances.Local actors are odontogenicumorssuchasameloblastic ibroma,odontogenicibroma, nd odon-

toma),cysts, malformedeeth, supernumeraryeeth,delayedooth development,nsufficientarch space, n-clination against the secondprimarymolar,and mu-

cosal barrier due to gingival fibrosis6. The ablesummarizeshe reported ases3 7-,0 of the impactionrdelayed ruption f the permanentirst molars, nclud-ing mandibular olars.Becausehe age at detection nmost eported ases s around 0 years, pediatricden-fists are moreikely hangeneral ractitionerso encoun-ter anddiagnoseuch ases. In most ases, odontogenictumorwasa contributingactor, as shownn the Table.Whenhe delayed ruption s caused y local factors,unilateral ailureusually ccurs. n ourcases, he fail-ure of eruptionwasunilateral, for whichocal factors

are indicated s the mostikely cause. n two aseseach,PediatricDentistry - 20. 1, 1998 AmericanAcademy f Pediatric Dentistry 55

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the pathological diagnosis was ameloblastic fibroma or

myxofibrous tissue. These odontogenic tumors and fi-

brous tissue impeded tooth emergence. Kramer et al.11

pointed out that a dental follicle may become thickened

when a tooth fails to erupt and that the thickened  folli-

cular fibrous tissue is often myxoid.

The  tooth development of all the unerupted maxil-

lary permanent first molars was delayed compared with

that of their counterpart. In two cases, the maxillary per-

manent second molars adjacent to the affected first mo-

lars also showed delayed development. This indicates

that delayed tooth formation on the affected  side may

be one reason  fo r delayed eruption.

As to the  treatment of the delayed eruption of the

maxillary permanent first molars, surgical intervention

is required. The surgical objective is to remove the im-

pediment and to assist eruption by exposing the crown.

After exposure of the crown, we usually observe the site

fo r  3 months, using radiography if the wound closed

following surgical exposure. In some cases, as in case 2,

a second surgical exposure may be necessary. If no ten-

dency to erupt is recognized, then traction  is applied as

in case 3. When the tooth development of the adjacent

second molar is also retarded and there are no pathologic

findings on die radiograph, we can keep the patient un-

der periodic observation as in case 4. Our  treatment  in

all  four patients involved exposure of the  tooth crown,

and  traction  was applied  in one case. All  four  delayed

maxillary first molars erupted satisfactorily.C o n c l u s i o n s

When we encounter a case of delayed eruption  of

first permanent molars, we remove the overlying tissue

or  pathological lesions surgically to expose the  crown

after checking the radiograph. When the development

of both the first and second molar is retarded and there

are no  pathological  radiographic findings, we periodi-

cally observe the patient and then decide whether sur-

gical intervention  is necessary. After surgical interven-

tion,  we observe  the  condition  and if we  cannot

recognize any tendency  to erupt, we apply traction.

Dr.  Tomizawa is an associate professor,  Dr.  Kohno an assistant pro-

fessor,  Dr. Yonemochi a clinical  instructor,  and Dr.  Noda  a pro-

fessor,  at the  Department o f  Pedodont ics , School o f  Dentistry,

Niigata University, Niigata, Japan. Reprint requests should be sentto Dr. Mieko Tomizawa, Department of Pedodontics, School  of

Dentistry, Niigata U niversity, Niigata, Japan.

R e f e r e n c e s1. Johnsen DC:  Prevalence of delayed emergence  of perma-

nent teeth  as a  result  of  local factors. J Am  Dent Assoc

94:100-106,1977.

2.  Dachi  SF,  Howell FV: A  survey of 3874  routine  full-

mouth radiographs.  IL A study  of  impacted teeth.  Oral

Surg Oral  Med Oral  Pathol 14:1165-69, 1961.

3. Grover PS, Lor ton  L: The  incidence of unerupted perma-

nent teeth and related clinical cases. Oral Surg Oral Med Oral

Pathol 59:420-25, 1985.

4.  Kramer RM, Williams AC: The incidence of impacted teeth.

A survey at Harlem hospital. Oral Surg Oral Med Oral Pathol

29:237^1, 1970.

5.  The chronology of deciduous and permanent dention in Japa-

nese children. The Japanese Society of  Pedodontics.  Shoni

Shikagaku 26:1-18,1988.

6.  Di Salvo NA:  Evaluation of  unerupted teeth: orthodontic

viewpoint. J Am Dent Assoc 82:829-35, 1971.

7.  Miller  AS, Lopez CF,  Pullon  PA ,  Elzay  RP: Ameloblastic

f ibro-odontoma. Report of seven cases. Oral Surg Oral Med

Oral Pathol 41:354-65,1976.

8.  Goho C: Delayed eruption due to overlying fibrous connec-

tive tissue. ASDC J Dent Child 54:359-60, 1987.9.  Spratley MH, Symons AL, Monsour FN:  Unerupted first

permanent molar.Case report. Aust Dent J 33:392-94,1988.

10. Matsuyama J, Tomizawa M, NodaT, Suzuki M, Fukushima

M: Four cases of odontogenic tumors causing delayed erup-

tion of lower permanent first molars. Jpn J Ped Dent 29:447-

58, 1991.

11 .  Kramer IRH, Pindborg JJ , Shear M: Histological Typing

of Odontogenic Tumors, 2nd Ed. Berlin: Sp ringer-Verlag,

pp 23 , 1992.

F lg  7 . Photom icrograph show ing th ehyperplastic  myxoid tissue  of thesubmucosal layer  ( H E , orig. m a g 25x1.

F ig  8. C a s e 4. Panoram ic radiographshowing  sligh t enlargem ent of thefollicular  sac of the ma xillary leftp erman en t first m olar. The root formationo f  the m olar is in the beginning stagewhile that o f the right co unterpart is one-third. Th e tooth development of theneighboring m axillary left second molar

is delayed com pared wi th the  antimere.

F ig  9 . C a s e 4 , P hotomicrograph showingimmature collagen fibers  irreg ularlydistributed in the   m y x o id tissue andodontogenic  ep ithelial island s (Oil  Hatorig  m a g . 25x1

56   American Academy ofPediatric  Dentistry Pediatric  Dentistry  20: J 1998