Rom J Morphol Embryol 2018, 59(3):879883 [626026]

Rom J Morphol Embryol 2018, 59(3):879–883
ISSN (print) 1220–0522 ISSN (online) 2066–8279 OORRIIGGIINNAALL PPAAPPEERR
Non-syndromic hypodontia of permanent dentition
associated with other dental anomalies in children
and adolescents
ADRIANA ȚENȚ, LIANA TODOR, GABRIELA CIAVOI, ANA-MARIA POPOVICI -MUȚ,
DANIELA DOMOCOȘ, MIHAELA DANA POGAN, LUMINIȚA LIGIA VAIDA,
ANCA PORUMB
Department of Dental Medicine, Faculty of Medici ne and Pharmacy, University of Oradea, Romania
Abstract
Anomalies of permanent dentition, by the frequency of the cases, also correspond to some unanimously recognized problems of pub lic
health. The objective of this study is to determine the prevalence of non-syndromic hypodontia and oligodontia and to identify the types of
associated dental anomalies in the permanent dentition of children and adolescents in the NW of Romania. The study was conducte d
between 2008 and 2015 on a group of 566 children aged between 12–18 years old. Dental agenesis was diagnosed using clinical and
radiological criteria. The numbers and types of teeth missing were noted. Third molars were excluded. Hypodontia had a prevalen ce of 2%
in girls and 3.76% in boys ( p=0.007), and oligodontia of 0.33% in girls and 0.38% in boys ( p=0.367). Unique abnormalities were registered
at 1% in girls and 1.5% in boys ( p=0.026), those with two associations at 0.67% in girls and 1.5% in boys ( p=0.015), and those with triple
association at 0.67% in girls and 1.13% in boys ( p=0.037). Hypodontia/oligodontia has been identified in association with other dental
abnormalities, such as inclusion, microdontia, and enamel hypomineralization. The most frequent was the association of hypodont ia with
enamel hypomineralization.
Keywords : hypodontia, permanent dentition, other dental anomalies.
 Introduction
Anomalies of permanent dentition represent an
important chapter of great practical relevance in pediatric
dentistry. These are pathologies with a wide range of clinical manifestations that include a major risk for the
child’s development through the complications they
generate, both locally and generally [1]. Dental abnor-malities may be syndromic or non-syndromic. The non-
syndromic ones are found isol ated or associated with
other dental abnormalities [2, 3]. Hypodontia designates a tooth abnormality characterized by the absence of fewer
than six permanent teeth, while oligodontia targets the
congenital absence of six or more permanent teeth. The congenital absence of certain dental elements could be
framed in the human evolution process, given the high
frequency of the third molar hypodontia in the current population. Agenesis of permanent teeth is the most
common abnormality of development, according to some
authors [4]. The prevalence of the agenesis of one or two
teeth, excluding the third molars, varies between 1.6–
9.6% [5]. One case, quoted by Levin (1985), presented
hypodontia associated with taurodontism and ravenous hair [5]. Other authors also point to associations between
hypodontia and taurodontism [6, 7] and supernumerary
teeth [8–11] between hypodontia associated with enamel hypomineralization [2, 10, 11].
Dental abnormalities undetected on time lead to a
series of disorders and imbalances: dental incongruities, dento-alveolar and occlusal equilibrium disorders, affecting masticatory, phonation and physiognomic functions, peri-
odontal problems, and dental caries. Undiagnosed and untreated on time, they can deeply affect the quality of
the individual’s life [1]. When a physical abnormality is
present, especially when it affects patients’ facial appea-rance or body appearance, this may have psychological and social consequences, being in most cases a major source of stress for patients and their family [12]. Consequently, any anomaly that is manifested in the
oral cavity results in a poor self-image and disrespect,
diminishing socio-human interactions, or leading to chronic pain, stress and depression. These conditions can also interfere with vital functions including breathing, food selection, speaking and daily activities, such as school and socio-human interactions [1]. On the other hand, the
treatment of dental anomalies has particularities related to
several factors, such as the la rge variety of clinical forms,
the severity of the abnormality, physician’s performance, and children’s behavioral traits [13]. Generally, treatment
for oligodontia requires a multidisciplinary approach and consists of artificial dentur es. Evolution of materials [13–
17] and dental restoration techniques over the past decades
is extremely important in the treatment of these anomalies.
Aim
The aim of this study is to determine the prevalence
of non-syndromic hypodontia and oligodontia and to identify the types of dental anomalies associated with
hypodontia/oligodontia in the permanent dentition of children and adolescents in the NW of Romania.
R J M E
Romanian Journal of
Morphology & Embryology
http://www .rjme.ro/

Adriana Țenț et al.
880
 Participants, Materials and Methods
The study was conducted between 2008–2015 on 566
children and adolescents aged between 12–18 years in
the NW of Romania, in accordance with the World Medical
Association (WMA) Declaration of Helsinki – Ethical
Principles for Medical Research Involving Human Subjects
approved by the Ethics Committee of the University of
Oradea, Romania.
All children were taken in the study with their parents’
consent, and in the case of adolescents, possibly with the
agreement of the latter too.
From the study were excluded children who refused
to be examined, those whose parents did not give their
consent for examination, those who had previously received orthodontic treatments or were under orthodontic treatment
when the batch was constituted, and children with severe
systemic illness that may influence, in a context of high clinical complexity, the integrity of the oral cavity: hemato-
oncological diseases, severe immune or autoimmune
diseases, disseminated infections [human immuno-deficiency virus/acquired immunodeficiency syndrome
(HIV/AIDS), tuberculosis, sepsis], etc.
The third molars were not subjected to clinical
observation. Diagnostic criteria included both clinical and
radiographic criteria. Past dental histories were checked
to ensure that extraction of permanent teeth was not diagnosed as agenesis.
Clinical methods
We examined the cephalic extr emity after the anamnesis.
Intraoral examination was performed with the help of
the instrumentation specific to the dental medical office.
All teeth present in the oral cavity as well as those included in the jaw or mandible were taken into account.
Hypodontia/oligodontia
Dental agenesis was diag nosed using clinical and
radiological criteria. The numbers and types of teeth
missing were noted. Third molars were excluded. In the case of children and adolescents with abnormalities of
number, represented by hypodontia/oligodontia, clinical
evaluation was made, consisting of medical and familial histories, extraoral and intraoral examination. In the intra-
oral examination, examining the teeth of the two arcades,
the persistence of some temporary teeth on the dental arcades, the absence of some teeth from the permanent
series whose eruption term was far exceeded, as well as
a thin, concave crest, suggested the tooth agenesis. For a hypodontia/oligodontia diagnostic certainty, patients
underwent paraclinical researches consisting of retro-
alveolar dental radiographs or panoramic radiographs.
Impacted and transmigrated teeth
In the intraoral examination, it was noticed the absence
of some teeth with exceeded eruption time. The inspection
was completed by paraclinical examinations for a diag-nostic certainty. It could be th e case of impacted teeth or
transmigrated teeth – situation in which an unerupted tooth (usually the canine) is migrating crossing the jaw
midline [17].
Microdontia
The diagnosis of microdontia was made following
the intraoral examination, comparing the tooth with its counterpart.
Enamel hypomineralization
There were subjected to ex amination the teeth present
in the oral cavity that have not been subjected to trauma or caries. The teeth presen t in the oral cavity were
considered to be those with all visible coronary surfaces.
This was ascertained mainly from clinical records and confirmed with radiographs whenever possible.
 Results
The girls prevailed in the study group, in number of
300 (53%), the girls/boys ratio being 1.1:1. Of the total of 566 investigated children, 18 (3.18%) were diagnosed with dental abnormalities, hypodontia and oligodontia. The prevalence of dental abnormalities was significantly lower in girls than in boys ( p=0.012). Hypodontia had a
prevalence of 2% in girls and 3.76% in boys ( p=0.007),
and oligodontia of 0.33% in girls and 0.38% in boys (p=0.367) (Table 1).
Table 1 – The prevalence of dent al abnormalities of
number
Abnormalities of number No. % p†
Girls 6 2
Hypodontia
Boys 10 3.76 0.007
Girls 1 0.33
Oligodontia
Boys 1 0.38 0.367
Girls 7 2.33
Total
Boys 11 4.44 0.012
†p<0.05 shows a statistically significant difference between the studied
groups.
In the case of the patients with hypodontia, in number
of 16 and a prevalence of almost 3%, congenital absence of at least one permanent tooth to six permanent teeth was found.
For patients with oligodontia, in number of two and
a prevalence of 0.35%, one shows the congenital absence of 16 permanent teeth and the other one of eight permanent teeth.
The highest incidence of congenital absence of some
teeth was recorded in the premolars level, followed by maxillary lateral incisors, canines, mandibular central incisors and molars (in decreasing order).
In premolars, secondary premolars agenesis was most
frequently encountered, followed by secondary mandibular premolars and first maxillary premolars.
The distribution of the prem olar agenesis on the two
arcades was unequal: there were nine ageneses of first and secondary premolars at the maxillary arcade level and four agenesis of secondary premolars at the mandibular arcade level.

Non-syndromic hypodontia of permanent dentition associated with other dental anomalies in childr en and adolescents
881
For the first maxillary premolars, agenesis was recorded,
while for the first mandibular premolars agenesis was not
registered.
For the maxillary secondary premolars, five ageneses
were recorded, while for the secondary mandibular
premolars there were four agenesis (Figure 1).
There were also differences regarding the premolar
ageneses of the right maxillary and of the left maxillary
hemiarcade: for the first maxillary premolars of the right hemiarcade there were record ed three ageneses, and for
their homologues on the right hemiarcade only one
agenesis; for the secondary premolars of the right maxillary hemiarcade, there were recorded two ageneses, while for
their counterparts on the left hemiarcade there were three
ageneses; for the first premol ars of the right mandibular
hemiarcade there were recorded two ageneses and for
their counterparts from th e left hemiarcade the same.

Figure 1 – 18-year-old boy: occlusal view of maxillary
arch reveals agenesis of teeth 12, 15, 25.
Regarding recorded lateral incisor ageneses, all
interested the maxillary lateral incisor. The distribution on the two hemiarcades, right and left, was uneven: five right lateral incisor ageneses and three of the lateral left incisor (Figure 2).

Figure 2 – 17-year-old boy with agenesis of 12, 22.
In case of canine ageneses, we identified three patients
with congenital absence of one to all four permanent
canines. On the mandibular arcade, the frequency of
congenital absence of the pe rmanent canine was higher
than at the maxillary level.
We have found a higher frequency of permanent canine
agenesis at the level of the right hemiarcade. One single
patient was diagnosed with agenesis of the first maxillary
and mandibular molars.
Unique abnormalities of number were in all the seven
(1.24%) cases of hypodontia. Eleven (61.11%) patients
of those with ageneses have other associated dental
abnormalities. Six cases with the presence of two (0.35%) dental
abnormalities were identified, four (0.71%) with number
and structure anomalies (Figure 3) and two (0.35%) with number and size anomalies. Five of the cases presented
three associated abnormalities, three (0.53%) with abnor-
malities of number + size structure and two (0.35%) with abnormalities of number + size + eruption.
Unique abnormalities were re gistered at 1% in girls
and 1.5% in boys ( p=0.026), those with two associations
at 0.67% in girls and 1.5% in boys ( p=0.015), and those
with triple association at 0.67% in girls and 1.13% in boys
(p=0.037).
In girls, associated abnormalities with hypodontia were:
hypodontia + enamel hypo mineralization – one case
(0.33%) (Figure 3), hypodontia + localized microdontia – one case (0.33%), hypodontia + generalized microdontia
+ enamel hypomineralization – one case (0.33%), oligo-
dontia + localized microdontia + dental inclusion – one case (0.33%).

Figure 3 – 18-year-old girl with hypodontia of 41, with
the presence of 81 and hy pomineralization of 11.
In boys, the abnormalities associated with hypodontia
were: hypodontia + enamel hypomineralization – three
(1.13%) cases, hypodontia + generalized microdontia + enamel hypomineralization – two (0.75%) cases, oligo-
dontia + localized microdontia + dental inclusion – one
case (0.38%) (Table 2).
Table 2 – Associated abnormalities with hypodontia
Abnormalities of number No. % p†
Girls 3 1
Unique
Boys 4 1.5 0.026
Girls 2 0.67 Two associated dental
abnormalities Boys 4 1.5
Girls 1 0.33 number + size
oligodontia/hypodontia +
localized microdontia Boys 1 0.38
Girls 1 0.33 number + structure
hypodontia + enamel
hypomineralization Boys 3 1.13 0.015
Girls 2 0.67 Three associated dental
abnormalities Boys 3 1.13
Girls 1 0.33 number + size + structure
hypodontia + generalized
microdontia + enamel
hypomineralization Boys 2 0.75
Girls 1 0.33 number + size + eruption
oligodontia + localized
microdontia + dental inclusion Boys 1 0.38 0.037
†p<0.05 shows a statistically significant difference between the studied
groups.

Adriana Țenț et al.
882
 Discussions
Dental ageneses, represented by hypodontia and oligo-
dontia, present in 18 of the 566 investigated children, record a total prevalence of 3.18%. Hypodontia records
a prevalence of 2.83%. Many authors report hypodontia
prevalence values between 1.6–16.3% [2, 5, 10, 18–25] the value obtained in this study being consistent with some previous ones.
Oligodonia falls within the parameters indicated by
other studies [5] and has a prevalence of 0.35%.
The most frequently absent teeth in the dental arches
were secondary mandibular premolars, consistent with
other studies [18–21] and in disagreement with other
authors that indicate the maxillary lateral incisor as the most common congenitally ab sent tooth in permanent
dentition [23].
Unique number abnormalities are represented by seven
cases with hypodontia, with a prevalence of 1.24%. In
literature, unique number abnormalities are less reported
[26–28].
It has usually been about hypodontia associated with
enamel hypomineralization. Other studies also indicate
this association as being superior to others [2, 11, 29].
With a lower prevalence and equal, in our casuistry
of 0.35%, the association of abnormalities of number
and of size is placed. There are authors who signal the
existence of such associations [2, 11, 18, 30, 31].
These associations, especially hypodontia/oligodontia
with localized microdontia, are relatively frequently encountered and reported [12, 29–31], also existing rare
reported cases of associations of abnormalities of position
with abnormalities of number [32].
 Conclusions
The prevalence of non-syndromic hypodontia/oligo-
dontia among children in the NW of Romania was of
3.18%. Hypodontia has a prevalence of 2.83%. Hypodontia/ oligodontia has been identified in association with other dental abnormalities such as inclusion, microdontia, and enamel hypomineralization. The most frequent was the
association of hypodontia w ith enamel hypomineraliza-
tion. In boys, associated dental abnormalities were more
common.
Conflict of interests
The authors declare that they have no conflict of
interests.
Authors’ contribution
Adriana Țenț and Lumini ța Ligia Vaida equally
contributed to the manuscript.
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Corresponding authors
Liana Todor, Lecturer, DMD, PhD, Depar tment of Dental Medicine, Faculty of Medicine and Pharmacy, University
of Oradea, 10 1 December Square, 410068 Oradea, Bihor County, Romania; Phone +40723–517 100, e-mail:
liana.todor@gmail.com
Gabriela Ciavoi, Lecturer, DMD, Ph D, Department of Dental Medicine , Faculty of Medicine and Pharmacy,
University of Oradea, 10 1 December Square, 410068 Oradea, Bihor County, Romania; Phone +40729–099 622,
e-mail: gabrielaciavoi@yahoo.com

Received: October 23, 2017
Accepted: November 29, 2018