Prevalence of dental agenesis in a sample of Italian orthodontic patients: an epidemiological study
Gracco et al. Progress in Orthodontics
Prevalence of dental agenesis in a sample of Italian orthodontic patients: an epidemiological study
Antonio L. T. Gracco 0
Serena Zanatta 0
Filippo Forin Valvecchi 0
Denis Bignotti 0
Alessandro Perri 0
Francesco Baciliero 1
0 Department of Neurosciences, Section of Dentistry, University of Padua , Via Giustiniani 2, Padua , Italy
1 Vicenza , Italy
Background: The congenital absence of one or more teeth is a dental anomaly that frequently occurs in the world's population with a wide variability of distribution. The aim of this study is to assess the current prevalence of dental agenesis in the permanent dentition (excluding third molars) using a sample of Italian orthodontic patients. Methods: Panoramic radiographs of 4006 Caucasian children between 9 and 16 years of age (1865 males and 2141 females) performed over a 5-year period (from 2010 to 2015) were carefully examined to identify congenital missing teeth. A chi-square test was used to determine the difference in the prevalence of hypodontia between genders and between arches. Results: The prevalence of dental agenesis was 9% (9.1% for females and 8.7% for males). The most common congenitally missing teeth were the mandibular second premolars (20.3 and 18.1%) followed by the upper lateral incisors (17.8 and 17.7%) and the maxillary second premolars (7.4 and 6.3%). The absence of one tooth to five teeth was observed in 344 patients (8.6%), while 15 patients showed from six to nine missing teeth (0.4%). The analysis showed 363 cases of agenesis in the upper arch (0.64%) and 339 in the lower arch (0.60%). Unilateral (4.6%) and bilateral (4.4%) agenesis demonstrated a similar frequency. The most common bilateral missing teeth were the mandibular second premolars (1.9%) and the maxillary lateral incisors (1.6%). Conclusions: The results of this study observed a higher prevalence of hypodontia compared to previous studies conducted on the Italian population. Thus, a detailed and careful radiographic examination was important in diagnosing one or more missing teeth. This could help plan the best possible treatments, both esthetically and functionally, for these patients.
Hypodontia; Prevalence; Dental agenesis
Tooth agenesis is considered one of the most common
anomalies of dental development and occurs with a high
frequency in the world’s population compared to other
development abnormalities [
]. Permanent dentition
(2.3 to 9.6%) is observed much more frequently than the
primary (0.1–0.7%) [
]. Congenital or developmental
absence of one or more teeth has been described in
literature with different terms [
2, 3, 7, 9, 10
absence of one to six teeth (excluding the third molars)
is generally called “hypodontia,” while the absence of
more than six teeth is named “oligodontia” and
“anodontia”, a very rare condition, is the absence of all teeth.
Hypodontia may occur both as non-syndromic form
as an isolated trait (familial agenesis) [
] and as a
manifestation of a genetic syndrome [
2, 4, 6
]. More than 49
syndromes have been associated with one or more missing
]; the main ones are hypohidrotic ectodermal
dysplasia, incontinentia pigmenti, Down syndrome,
craniofacial dysostosis, and syndromes associated with
growth and development defects [
Studies based on prevalence and distribution of
hypodontia demonstrated a high variability depending on sample
size, gender, race, and ethnic provenance [
1, 8–10, 12, 13
A meta-analysis conducted by Polder showed that
prevalence varied in the world from 2.2% in the Saudi
Arabia to 6.3% in the Australian population. In the
European population, it varied from 3.4% in Switzerland
to 10.1% in the population of Norway [
A Medline research project performed in June 2015
found five studies on the prevalence of hypodontia in
the Italian population [
]. The most recent was
published in 1993, so our purpose was to assess whether
the prevalence of congenital missing teeth had changed
compared to previous studies. Moreover, this is the first
research project performed in Italy on a sample of
The purpose of this study was to examine the current
prevalence and distribution of hypodontia in the
permanent dentition (excluding third molars) in a sample of
Italian orthodontic patients, determining which are the
most affected teeth and to compare our results with
those of other studies.
This is a retrospective, observational, and multicentric
study. The research was approved by the Ethics
Committee of the Medical School of the University of Padua
(protocol number 41648). All patients signed a formal
consent for researchers to use and publish their personal
data in the research project.
The initial sample included all panoramic radiographs
of Italian orthodontic patients (4196) between 9 and
16 years of age performed over a 5-year period (2010–
2015) at the Dental School of the University of Padua
and two private dental offices located in Vicenza and
Verona. All patients visited these dental clinics for an
orthodontic evaluation. The radiographic machines were
the same with uniform features. The inclusion criteria
for this study were patients of Caucasian origin, patients
with no history of medical problems, patients with no
history of any syndrome, presence of panoramic
radiograph with good quality, and patients between 9 and
16 years of age.
All selected files were examined by the same operator
in a dark room using X-ray viewer to identify the
presence of dental agenesis (excluding third molars). A
tooth was diagnosed as congenitally missing if the
mineralization of its crown could not be identified on
orthopantomogram. The operator analyzed the records
and the medical history of the patients and excluded
190 records, considering the following exclusion
criteria: agenesis of third molars, patients with missing
teeth for decay processes, avulsions or extracted for
orthodontics or other reasons, panoramic radiography
of Non-Caucasian patients, patients with facial clefts
and craniofacial syndromes, and poor image quality of
panoramic radiographs. The final sample of this study
included 4006 panoramic radiographs: 1865 males with
a mean age of 11.1 years and 2141 females with a mean
age of 12.4 years. Data obtained from panoramic
radiographs and patients’ records were recorded according
to gender, subject’s date of birth, age at time of
radiography, number of missing teeth and their location,
maxillary versus mandibular agenesis, and right versus
The data was analyzed using the R software version 3.2.2
(R Core Team, 2015) on Linux/Ubuntu 12.04.
Data found in this study was described using
descriptive statistical analysis. The chi-square statistical test was
applied to analyze the frequency of agenesis between
genders (males/females) and between maxilla and
mandible; the level of significance was set at P < 0.05.
The final dataset comprised 4006 patients of Caucasian
origin, of which 3647 had no missing permanent teeth.
A total of 196 females and 163 males examined showed
at least one congenitally missing tooth (excluding third
molars), bringing the total to 359 patients. The female
hypodontia prevalence was higher than males (9.1 and
8.7%, respectively), although difference between gender
was not statistically significant. The overall prevalence of
hypodontia was found to be 9% of the total sample
population. The overall prevalence of oligodontia was
0.4% of the studied sample: there were 15 patients, nine
females (0.22%) and six males (0.15%) with the absence
of six or more teeth excluding the third molars (Table 1).
In 359 patients, a total of 702 permanent teeth were
missing (401 in females [0.7%] and 301 in males [0.6%]).
Of all the examined patients, 176 had one missing tooth
(4.4%), 127 (3.2%) had two missing teeth, 19 (0.5%)
had three missing teeth, 17 (0.4%) had four missing
teeth, and 5 (0.1%) had five missing teeth. The
difference between males and females was not statistically
different (Fig. 1).
The most commonly congenitally missing teeth were
the lower left second premolar (20.3% of the sample),
followed by the lower right second premolar (18.1%), the
upper lateral incisors (17.8 and 17.7%), the upper left
second premolar (7.4%), the upper right second
premolar (6.3%), and the upper right first premolar (2.6%).
There were no significant differences between the right
and left sides for any particular tooth (Table 2).
There were 363 missing teeth in the maxilla (0.64%)
and 339 missing teeth in the mandible (0.60%). The
number of missing teeth in the maxilla was slightly
Table 1 Distribution of the patients by gender and number of missing teeth
Number of missing teeth Males
Patients with dental agenesis From 1 to 5 (hypodontia) 157 (3.9%)
6 or more (oligodontia) 9 (0.2%)
Patients without dental agenesis No one 1702 (42.5%)
Total 1868 (46.6%)
Fig. 1 Frequencies and percentages of agenesis in males, in females, and in total sample
higher, but the difference between the two arches was
not statistically significant (χ2 (1) = 0.76, P = 0.38).
There were 118 patients with one missing tooth in the
upper arch (2.9%) while in the lower arch there were 90
(2.2%). In the upper arch, there were 90 patients with
two missing teeth (2.02%), and in the lower arch, there
were 84 (2.09%) (Table 3).
There were at least 218 patients with at least one
missing tooth in the maxilla (5.4%), while there were fewer
patients missing at least one tooth in the mandible,
equal to 195 (4.7%). The number of patients with
agenesis did not differ statistically significantly between the
maxilla and the mandible (χ2 (1) = 1.23, p = 0.26).
Unilateral agenesis occurred with a frequency of 4.6%;
bilateral agenesis manifested a frequency of 4.4%.
Unilateral and bilateral agenesis had the same probability of
occurrence, with no difference between genders: 4.4% of
females had a unilateral agenesis and 4.8% a bilateral
agenesis. Likewise, 4.7% of males showed a unilateral
agenesis and 4.0% a bilateral agenesis. The chi-square
test pointed out a similarity of males and females on this
feature (χ2 (2) = 1.49, p = 0.47).
Teeth that resulted missing simultaneously were
mainly mandibular second premolars (1.9%) and the two
maxillary lateral incisors (1.6%). This pairing of agenesis
can also sometimes be found missing in cross
combination: patients with four or more missing teeth
presented the agenesis of mandibular second premolars
combined with the two lateral incisors or with the
maxillary second premolars.
We defined “co-occurrence” as the concomitant
lack of two teeth; we calculated the patients in which
each tooth was missing in conjunction with all others.
We built a graph in which each node represented a
tooth (Fig. 2).
The prevalence of tooth agenesis, excluding third
molars, was observed at 4.89% among females and 4.07%
for males, for a total of about 9% for both sexes together.
This result showed a higher prevalence compared with
the two previous Italian studies on this topic and
confirms that hypodontia is a common developmental
anomaly in Italian children. In the analysis of Lo Muzio
et al., the prevalence was 5.17% [
], and according to
the data of Polastri et al., the prevalence was 5.14% [
The sample studied by Polastri et al. included 700
national servicemen aged between 19 and 26, so it was
much smaller and very different from our sample of
patients. This research is the first of its kind in Italy
analyzing the prevalence of dental agenesis in a sample of
orthodontic patients. Comparing our results with those
of a study of the non-orthodontic Italian sample, we
found a slightly higher prevalence of dental agenesis
(9% against 7.1%), perhaps because it is more likely that
a patient with one or more missing teeth gets to an
According to literature review on the prevalence of
agenesis, we could state that the range of prevalence
values varies from 2.8% in the Malaysian population [
to 12.6% in the German population [
Also, in the same population, different studies reported
various values of prevalence: Celikoglu et al. determined
prevalence of 4.6% in Turkish orthodontic patients [
while Sisman et al. found a prevalence of 7.54% in another
sample of the Turkish population [
The result of this study pointed out a higher
prevalence in Italy than in most other countries. A higher
prevalence rate was found in a few other studies: Chung
et al. estimated a prevalence of 11.2% in Korean
] and Hunstadbraten of 10.1% in Norway [
very high prevalence was also reported in two German
studies (12.6% [
] and 11.3% [
]). The wide range of
prevalence values observed in these studies has indicated
that geographic, gender, races, and genetics differences
as well as the big differences in the sample size and
criteria of selection play a fundamental role in the varied
results of studies of hypodontia. This wide range could
make the comparison of the result of this study very
limiting with other previous studies.
Polder examined a total of 28 studies and concluded
that the prevalence of dental agenesis in females was
almost 1.4 times higher than in males [
]. In this study,
there was no significant difference between the
prevalence of hypodontia in males (4.07%) and females
(4.89%). Females presented a higher prevalence of
congenital missing teeth, which is in agreement with the
majority of reports by Grahnèn [
], Haavikko [
], and Endo et al. [
]. But Larmour et al. [
found that in the primary dentition, there was no gender
distribution, while in the permanent dentition, females
are affected more frequently than males by a ratio of 3:2.
In the study of Behr et al. on the German population
] and of Laganà et al. on a non-orthodontic Italian
], the percentage was equally distributed
between males and females.
Usually, a patient’s first visit to a dental clinic for an
orthodontic evaluation occurred between the ages of 9
and 12. However, patients at the same chronological age
can have significant differences in mineralization stages.
These major differences in mineralization can be found
in the lower second premolar buds [
To prevent a false-positive diagnosis of agenesis, we
selected 9 as the minimum age because calcification of
teeth has usually not been completed by this age [
to prevent classification of late mineralized teeth as
congenitally missing, final longitudinal panoramic views
were also used to confirm a diagnosis of hypodontia.
In the present study, of the individuals identified with
congenitally missing teeth, 84% had one or two missing
teeth; this is in accordance with other studies by Davis
], Fekonja [
], Gomes et al. [
], and Goya et al. [
Thus, most of the affected individuals suffer only a mild
form of hypodontia.
We found that the most often congenital missing
tooth types in patients observed in our study were
mandibular second premolars, followed by maxillary lateral
incisors and maxillary second premolars. Lo Muzio et al.
] and Laganà et al. [
] had similar findings in the
previous study on the Italian population, whereas
] found that the most affected tooth was the
maxillary lateral incisor followed by the mandibular
There is some variation in the literature concerning
the description of the most frequently missing tooth,
excluding third molars. In the European population, the
teeth that were most frequently affected by hypodontia
are the following: mandibular second premolar, maxillary
lateral incisor, and maxillary second premolar [
mandibular second premolar is the most frequently
missing tooth also reported by Polder et al. [
], Endo et
], Tunc et al. [
], Goya et al. [
], and Kirzioglu et
]. In Malaysian [
], Turkish [
], and American
populations, the most commonly missing tooth was the
maxillary lateral incisor [
]. In the Chinese population,
the most frequently missing teeth are mandibular central
and lateral incisors [
]. Teeth with the lowest frequency
of agenesis were canines (6 males and 15 females) and
the first molars (0 males and 3 females). The first molar
was missing only in patients with oligodontia.
We found more missing teeth in the maxilla than in
the mandible, and the difference was not significant.
This result corresponds with the analysis performed by
Peker et al. [
], as well as Fekonja [
] and Wong et al.
] who found missing teeth considerably more
frequently in the upper arch than in the lower arch in
orthodontic patients. However, Kirzioglu [
more missing teeth in the mandible than in the maxilla.
Gomes et al. [
] found maxillary hypodontia in 59.2%
of patients and in the mandible of 40.8% with an overall
ratio of 1.45:1 in orthodontic patients.
Bilateral agenesis manifested a frequency of 4.4%. The
most common bilaterally missing teeth were the
mandibular second premolar and the maxillary lateral incisor. Goya
et al. [
] found that symmetry of congenitally missing
teeth was predominant (74.6%), and Kirzioglu et al. [
observed that bilaterally missing teeth was 73.2%.
Moreover, symmetrical hypodontia was predominant, being
found in both the contralateral and antagonistic quadrant,
possibly suggesting a strong genetic pattern of hypodontia.
It was demonstrated also that permanent tooth agenesis,
maxillary lateral incisor microdontia, palatally displaced
canines, and distoangulation of mandibular second
premolars were frequently associated with maxillary lateral
incisor agenesis, providing additional evidence of a
genetic interrelationship in the causes of hypodontia [
Moreover, a significant decrease in maxillary transversal
and sagittal size was demonstrated in patients with
dental agenesis [
We found a higher prevalence of congenital missing teeth
(9%) compared to previous similar studies, so hypodontia
is not an uncommon anomaly in the Italian population.
There were no significant differences in the distribution of
congenitally missing teeth between the sexes or in
localization by arches and quadrant sides. The mandibular
second premolars were the most frequently missing teeth,
followed by the maxillary lateral incisors and maxillary
second premolars. By early detection of missing teeth,
alternative treatments can be discussed and planned with
a multidisciplinary team to minimize the complications of
congenital missing teeth and to restore the patient’s dental
esthetics and functionality.
All authors have approved the manuscript for submission.
This manuscript has not been published and is not under consideration
for publication elsewhere. The authors declare that they have no
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
1. Rakhshan V . Meta-analysis and systemic review of factors biasing the observed prevalence of congenitally missing teeth in permanent dentition excluding third molars . Prog Orthod . 2013 ; 14 : 33 .
2. Bural C , Oztas E , Ozturk S , Bayraktar G. Multidisciplinary treatment of nonsyndromic oligodontia . Eur J Dent . 2012 ; 6 : 218 - 6 .
3. Closs LQ , Weissbluth MF , Nakamura E , Hermann FP . Esthetic and functional rehabilitation for oligodontia in the mixed dentition: case report . J Dent Child . 2012 ; 79 ( 3 ): 193 - 6 .
4. Parkin N , Elcock C , Smith RN , Griffin RC , Brook AH . The aetiology of hypodontia: the prevalence, severity and location of hypodontia within families . Arch Oral Biol . 2009 ; 54 ( 1 ): S52 - 6 .
5. Garib DG , Alencar BM , Lauris JR , Baccetti T. Agenesis of maxillary lateral incisors and associated dental anomalies . Am J Orthod Dentofac Orthop . 2010 ; 137 ( 6 ): 732 .e1- 6 .
6. Fekonja A . Hypodontia in orthodontically treated children . Eur J Orthod . 2005 ; 27 ( 5 ): 457 - 60 .
7. Punithavathy , John JB , Priya G , Elango I , Stalin. Familial nonsyndromic oligodontia . Contemp Clin Dent . 2012 ; 3 ( Suppl 2 ): S188 - 90 .
8. Endo T , Ozoe R , Kubota M , Akiyama M , Shimooka S . A survey of hypodontia in Japanese orthodontic patients . Am J Orthod Dentofac Orthop . 2006 ; 129 : 29 - 35 .
9. Shimizu T , Maeda T . Prevalence and genetic basis of tooth agenesis . Japanese Dental Science Review . 2009 ; 45 : 52 - 8 .
10. Polder BJ , Van't Hof MA , Van der Linden FP , Kuijpers-Jagtman AM . A meta-analysis of the prevalence of dental agenesis of permanent teeth . Community Dent Oral Epidemiol . 2004 ; 32 : 217 - 26 .
11. Barberìa E , Saavedra D , Arenas M , Maroto M. Multiple agenesis and anhidrotic ectodermal dysplasia: a comparative longitudinal study of dental similarities and genetic differences in two groups of children . Eur J Paediatric Dent . 2006 ; 7 ( 3 ): 112 - 21 .
12. Kavadia S , Papadiochou S , Papadiochos I , Zafiriadis L . Agenesis of maxillary lateral incisors: a global overview of the clinical problem . Orthodontics (Chic) . 2011 ; 12 ( 4 ): 296 - 317 .
13. Rakhshan V , Rakhshan H . Meta-analysis of congenitally missing teeth in the permanent dentition: prevalence, variations across ethnicities, regions and time . Int Orthod . 2015 ; 13 ( 3 ): 261 - 73 .
14. Lo Muzio L , Mignogna MD , Bucci P , Sorrentino F . Indagine statistica sull'incidenza delle agenesie in un campione di 1529 soggetti . Minerva Stomatol . 1989 ; 28 : 1045 - 51 .
15. Polastri F , Cerato E , Gallesio C . Valutazione clinico-radiologica delle anomalie dentarie di numero in difetto reali ed apparenti . Minerva Stomatol . 1991 ; 40 : 415 - 23 .
16. Vona G , Piras V , Succa V , Distinto C . Dental agenesis in Sardinias . Anthropol Anz . 1993 ; 51 ( 4 ): 333 - 40 .
17. Rasà R , Tripi F , Scolaro A. Clinical-statistical study of dental agenesis in a group of 412 subjects . Stomatol Mediterr . 1987 ; 7 ( 1 ): 113 - 8 .
18. Sticco E , Comisso E , Clarich MG . The prevalence of agenesis in a sample of 2954 school-age subjects in Trieste Province . Minerva Stomatol . 1990 ; 39 ( 5 ): 403 - 5 .
19. Nik-Hussein NN . Hypodontia in the permanent dentition: a study of its prevalence in Malaysian children . Aust Orthod J . 1989 ; 11 ( 2 ): 93 - 5 .
20. Behr M , Proff P , Leitzmann M , Pretzel M , Handel G , Schmalz G , et al. Survey of congenitally missing teeth in orthodontic patients in Eastern Bavaria . Eur J Orthod . 2011 ; 33 : 32 - 6 .
21. Celikoglu M , Kazanci F , Miloglu O , Oztek O , Kamak H , Ceylan I . Frequency and characteristics of tooth agenesis among an orthodontic patient population . Med Oral Patol Oral Cir Bucal . 2010 ; 15 : e797 - 801 .
22. Sisman Y , Uysal T , Gelgor IE . Hypodontia. Does the prevalence and distribution pattern differ in orthodontic patients? Eur J Dent . 2007 ; 1 : 167 - 73 .
23. Chung CJ , Han JH , Kim KH . The pattern and prevalence of hypodontia in Koreans . Oral Dis . 2008 ; 14 : 620 - 5 .
24. Grahnén H. Hypodontia in the permanent dentition . Odontol Revy . 1956 ; 7 ( 3 ): 1 - 100 .
25. Haavikko K. Hypodontia of permanent teeth. An orthopantomographic study . Suom Hammaslaak Toim . 1971 ; 67 ( 4 ): 219 - 25 .
26. Larmour CJ , Mossey PA , Thind BS , Forgie AH , Stirrups DR . Hypodontia-a retrospective review of prevalence and etiology . Quintessence Int . 2005 ; 36 ( 4 ): 263 - 70 .
27. Laganà G , Venza N , Borzabadi-Farahani A , Fabi F , Danesi C , Cozza P. Dental anomalies: prevalence and associations between them in a large sample of non-orthodontic subjects, a cross-sectional study . BMC Oral Health . 2017 ; 17 : 62 .
28. Moorrees CFA , Fanning EA , Hunt EE Jr. Age variation of formation stages for ten permanent teeth . J Dent Res . 1963 ; 42 : 1490 - 502 .
29. Prahl-Andersen B , Van der Linden FPGM . The estimation of dental age . Trans Eur Orthod Soc . 1972 ; 1 : 535 - 41 .
30. Cunat JJ , Collord J . Late-developing premolars: report of 2 cases . J Am Dent Assoc . 1973 ; 87 : 183 - 5 .
31. Fass EN . Aberrant second premolars . J Dent Child . 1971 ; 37 : 494 - 8 .
32. Ravn JJ , Nielsen HG . A longitudinal radiographic study of the mineralization of 2nd premolars . Scand J Dent Res . 1977 ; 85 : 232 - 6 .
33. Davis PJ . Hypodontia and hyperdontia of permanent teeth in Hong Kong schoolchildren . Community Dent Oral Epidemiol . 1987 ; 15 ( 4 ): 218 - 20 .
34. Gomes RR , Fonseca J , Paula LM , Faber J , Acevedo AC . Prevalence of hypodontia in orthodontic patients in Brazil . Eur J Orthod . 2010 ; 32 ( 3 ): 302 - 6 .
35. Goya HA , Tanaka S , Maeda T , Akimoto Y. An orthopantomographic study of hypodontia in permanent teeth of Japanese pediatric patients . J Oral Sci . 2008 ; 50 : 143 - 50 .
36. Tunc EŞ , Bayrak S , Koyuturk AE . Dental development in children with mildto-moderate hypodontia . Am J Orthod Dentofac Orthop . 2011 ; 139 ( 3 ): 334 - 8 .
37. Kirzioglu Z , Sentut TK , Erturk MSO , Karayilmaz H. Clinical features of hypodontia and associated dental anomalies: a retrospective study . Oral Dis . 2005 ; 11 ( 6 ): 399 - 404 .
38. Peker I , Kaya E , Darendeliler-yaman S. Clinical and radiographical evaluation of non-syndromic hypodontia and hyperdontia in permanent dentition . Med Oral Patol Oral Cir Bucal . 2009 ; 14 ( 8 ): e393 - 7 .
39. Wong ATY , McMillan AS , McGrath C . Oral health-related quality of life and severe hypodontia . J Oral Rehabil . 2006 ; 33 ( 12 ): 869 - 73 .
40. Gamba Garib D , Alencar BM , Pereira Lauris JR , Baccetti T. Agenesis of maxillary lateral incisors and associated dental anomalies . Am J Orthod Dentofac Orthop . 2010 ; 137 : 732 .e1- 6 .
41. Laganà G , Lombardi CC , Franchi L , Cozza P . Tooth agenesis: dentoskeletal characteristics in subjects with orthodontic treatment need . Eur J Paediatric Dent . 2011 ; 12 ( 1 ): 17 - 20 .