Full text of DOI:10.1038/sj.bdj.4800390a

PRACTICE
case study
Retention of permanent incisors by
mesiodens: a family affair
a
1
2
M Mercedes Gallas, and A García,
Radiography showed a pair of supernumer-
ary teeth in the same positions as in Case 1,
though with less developed roots. The gen-
eral morphology and position of the super-
numerary teeth were identical in the
radiographs of both sisters (Fig. 1 and Fig. 2).
Again, surgical removal of the supernumer-
ary teeth was followed by removal of bone.
In neither case did histological examina-
tion show the dental tissues of the supernu-
merary teeth to differ from those of normal
teeth.
The term mesiodens refers to a supernumerary tooth that is
present in the midline of the maxilla between the two central
incisors. One or two mesiodentes may be present. We present a
rare case of two sisters, in both of whom a pair of mesiodentes
caused the retention of permanent incisors. They were referred
to our hospital with asymptomatic delayed eruption of upper
incisors. This article is written to point out genetic factors as the
possible origin of supernumerary teeth.
t is widely assumed that the development
I
of supernumerary teeth may involve a
Discussion
In brief
1
genetic factor. Supernumerary teeth are
relatively common in the general popula-
tion and appear to be more likely to occur
in patients with a family history of such
teeth.
Several theories have been proposed for the
etiology of hyperdontia: theory of differen-
tiation, theory of concrescence, post per-
manent theory, dichotomy theory and
hyperactivity theory. However the hyper-
activity theory, which states that supernu-
merary teeth are derived from independent
local hyperactivity of the dental lamina,
has been more accepted. According to this
hypothesis the lingual extension of an
additional tooth bud leads to a eumorphic
mesiodens, while the rudimentary form
arises from proliferation of epithelial rem-
ꢀ Although uncommon, anterior
maxillary supernumerary teeth
(mesiodentes) are the most frequent
supernumerary teeth.
ꢀ The etiology of this dental anomaly
remains unclear.
ꢀ There probably exists a familial
disposition.
ꢀ This paper will try to underline the
importance of genetics as a key
factor in the development of
supernumerary teeth.
In the Caucasian population the inci-
dence of supernumerary teeth ranges from
1% to 3%. The mesiodens is the most fre-
quent supernumerary tooth with a preva-
lence of 0.15% to 1.9%. Mesiodens appears
to be more common in males than in
2
3
females with a male-female ratio of 2:1.
Familial occurrence of mesiodens is
reported to involve more than one sibling, dentes caused the retention of permanent nants of the dental lamina induced by pres-
2,4–6
8,9
or one generation.
In some cases, this incisors. Unfortunately, no information was sure of the dentition.
anomaly has also been seen in more than available concerning similar anomalies
There appears to be evidence to suggest
a familial predisposition to producing
extra teeth. Many published cases of
supernumerary teeth mention reincidence
within the same family, but without inves-
tigating this aspect in detail. Such cases
7
one generation.
among their forebears.
There are many publications that focus
on clinical, radiological and surgical or sur- Case reports
gical-orthodontic aspects of the treatment
of mesiodentes. However, the etiology and Case 1
the genetic considerations of this dental In a 13-year-old-girl, referred with delayed include that of two brothers, in one of
anomaly remains unclear. eruption of the permanent central maxillary whom a mesiodens appeared with the
In this report, we present a rare case of two incisors, both deciduous central maxillary deciduous teeth and in the other the
sisters, in both of whom a pair of mesio- incisors were present. A review of her med- mesiodens appeared at the same time as
5
ical history showed nothing remarkable. the permanent incisors. In another case,
Radiography showed that two supernumer- two brothers, aged 11 and 12 years, one of
ary teeth in the anterior maxilla were pre- whom had typical conical mesiodens and
venting the eruption of the permanent the other who had an unusual molariform
incisors. The supernumerary teeth were mesiodens (mesiodens with coronal mor-
1
Research Assistant of Oral Surgery Unit, School of
Dentistry, Faculty of Medicine and Dentistry,
University of Santiago de Compostela, Spain
2
Chief of Section, Department of Maxillofacial
Surgery, Hospital General de Galicia, Santiago de
Compostela, and Senior Lecturer in Maxillofacial
Surgery, University of Santiago de Compostela, Spain
removed surgically, and removal of bone phology vaguely similar to that of
was performed to facilitate the rapid erup- molar); and that of a brother and a sister,
a
6
tion of the permanent incisors.
one with an inverted mesiodens and one
with an uninverted mesiodens. The latter
a
Correspondence to: M Mercedes Gallas, Facultad de
2
Medicina y Odontología, Rúa Entrerríos, S/N,
Santiago de Compostela, C.P.: 15705, Spain
e-mail: zodousc@usc.es
Case 2
two reports did not mention the absence
In the maxillary arch of the 8-year-old-sister of similar abnormalities in the parents.
2
of the subject of Case 1, the permanent cen- Sedano et al. nevertheless suggested that
REFEREED PAPER
tral incisors had erupted without the decidu- mesiodens is an autosomal dominant trait
ous central incisors having exfoliated. with lack of penetrance in some genera-
Received 09.03.99; accepted 13.08.99
© British Dental Journal 1999; 188: 63–64
BRITISH DENTAL JOURNAL, VOLUME 188, NO. 2, JANUARY 22 2000
63

PRACTICE
case study
10
tions. Bruning et al. has even proposed
the possibility of sex-linked inheritance
caused by the existence of a sex predomi-
nance of males over females. Cadenat et
7
al. pointed out that there is a recessive
gene on an autosome and a gene on the
inhibiting X chromosome. These authors
refuted the theory of mutation and finally
reported the case of mesiodens in two
non-identical twins and in their grandfa-
ther. Although no investigation proved
the hereditary condition of the mesiodens,
Fig. 1 Orthopantomograph Case 1
it is quite possible, in view of the patients
3
showing
a
familial
disposition.
Many authors suggested inheritance as
a
key factor in the development
2,3,7,10
11
of mesiodens.
Brook postulated
a
multifactorial polygenic model of
quasi-continuous traits for simultaneous
consideration of supernumeraries, mega-
dontia, oligodontia and microdontia. Nis-
12
lander and Sujaku compiled data for
supernumerary teeth, and theorised that
this trait may be associated with an auto-
somal recessive gene with lesser pene-
trance in the female. Further support of a
genetic component in hyperdontia is evi-
denced by their simultaneous occurrence
Fig. 2 Orthopantomograph Case 2
1
2
3
4
5
6
7
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Pathology. 6th ed. St. Louis-Toronto-Princeton
Barcelona: Salvat Ed. C.V. Mosby. 1973: 124-126.
Sedano H O, Gorlin R J. Familial occurrence of
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1969; 27: 360-362.
Stellzig A, Basdra E K, Komposch G.
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J Orofac Orthop 1997; 58: 144-153.
Marya C M, Kumar B R. Familial occurrence of
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Molleda Medrano N. Algunos casos de dientes
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Nadal-Valldaura A. Un caso de dos hermanos
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Cadenat H, Combelles R, Fabert G, Clouet M.
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10 Bruning L J, Dunlop L, Mergele M E. A report
of supernumerary teeth in Houston, Texas
school children. J Dent Child 1957; 24: 98-
105.
11 Brook A H. A unifying aetiological explanation
for anomalies of human tooth number and
size. Archs Oral Biol 1984; 29: 373-378.
12 Nislander J D, Sujaku C. Congenital anomalies
of teeth in the Japanese children. Amer J Phys
Anthrop 1963; 21: 569-574.
13 Rubin M M, Nevins A, Berg M, Borden B. A
comparison of identical twins in relation to
three dental anomalies: multiple supernumerary
teeth, juvenile periodontosis, and zero caries
incidence. Oral Sur 1981; 52: 391-394.
14 Böhn A. Dental anomalies in harelip and cleft
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Supp. 38.
15 Richardson A, Deussen F F. Facial and dental
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231.
13
in identical twins.
The presence of hyperdontia may be
associated with various developmental dis-
orders. The two most common disorders
with a significant incidence of a supernu-
14
merary teeth are cleft lip and cleft palate,
15
and cleidocranial dysplasia. Less frequent
developmental disorders are Gardner’s
Syndrome, Fabry-Anderson’s Syndrome,
chondroectodermal dysplasia (Ellis-van
Greveld Syndrome), incontinentia pig-
menti, and tricho-rhino-phalangeal syn-
1,8,16,17
drome.
However, neither of our
patients had any symptoms suggestive of a
syndromic background.
Human dental eruption is known to be a
dynamic interaction between genetics and
the environment, each one affecting and
being affected by the other. Therefore,
changes in the initial stages result in
hyperdontia, such as mesiodens, or
hypodontia. From our point of view a
more detailed investigation into family
history of patients with mesiodentes is
needed.
8
9
Sykaras S N. Mesiodens in primary and
permanent dentition. Oral Surg 1975; 39:
870-874.
Pindborg J J. Pathology of Dental Hard Tissues.
Philadelphia: W. B. Saunders Company. 1970;
26-33.
16 Regattieri L R, Parker J L. Supernumerary teeth
associated with Fabry-Anderson’s Syndrome.
Oral Surg 1973; 35: 432-433.
17 Gorlin R J, Cohen M M, Wolfson J. Tricho-
Rhino-Phalangeal Syndrome. Am J Dis Child
1969; 118: 595-599.
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