prevalence/distribution of dental anomalies in thai orthodontic patients

Int J Med Health Sci. April 2015,Vol-4;Issue-2 165

International Journal of Medical and Health Sciences

Journal Home Page: http://www.ijmhs.net ISSN:2277-4505

Prevalence and Distribution of Dental anomalies in Thai Orthodontic Patients

Weeraya Tantanapornkul1*

1Department of Oral Diagnosis, Faculty of Dentistry, Naresuan University, Muang, Phitsanulok, 65000,Thailand.

ABSTRACT

Purposes: To evaluate the prevalence and distribution of dental anomalies, including other abnormalities in the pre-treatment

panoramic radiographs in a sample of Thai orthodontic patients, which were taken at dental hospital, Faculty of Dentistry,

Naresuan University and private dental clinic in Phitsanulok, Thailand between January, 2012 and October, 2014. Materials and

Methods: A retrospective study was conducted to evaluate the panoramic radiographs. Dental anomalies and other abnormalities

were recorded. The prevalence and distribution of the anomalies were assessed and reported as descriptive statistics. Results: 638

panoramic radiographs were evaluated. Patients were between 13 and 30 years of age (mean 19.2 ± 3.39 years), 39.5 % of patients

had at least one dental anomaly. Dilaceration was the most common (29.16 %), followed by missing tooth (13.17 %), microdontia

(7.21 %), taurodontism (3.29 %), supernumerary tooth (2.66 %), transposition (1.56 %), and the other anomalies (0.155 % – 0.47

%). Conclusion: At least one dental anomaly was found in a sample of Thai orthodontic patients. Dilaceration was the most common anomaly. The prevalence and distribution of dental anomalies are different between the parts of Thai orthodontic patients

and between the races.

KEYWORDS: Dental anomalies, panoramic, orthodontic patient.

INTRODUCTION

Dental anomalies have long been a concern to dental

profession. Abnormalities in tooth size, shape, and structure

result from disturbances during the morpho-differentiation

stage of development, while ectopic eruption, rotation and

impaction of teeth result from developmental disturbances in

the eruption pattern of the permanent dentition [1]. In addition, various maxillofacial pathologies can affect the

jaw size, occlusion, diagnosis and treatment plan of

orthodontic patients.

Although orthodontic patients have been reported to have

high rates of dental anomalies, orthodontists often fail to

consider this [2-4]. If not detected, they can complicate

dental and orthodontic treatment. Therefore, orthodontists

and general dental professional should carefully investigate.

Their incidence and degree of expression can provide

important information for phylogenic and genetic studies

and help in the understanding of differences within and

between populations [4]. Several studies have investigated

the prevalence of dental anomalies in various age groups

and race.

Fekonja[5] reported a hypodontia frequency of 11.3% in 212

orthodontically treated children, which was higher than the

incidence of hypodontia reported in other studies of the

same patients’ age. Altug-Atac and Erdem[2] reported

5.46% of the orthodontic patients in a group of 3,043 had at

least 1 developmental anomaly, while Thongudomporn and

Freer[6] investigated 111 orthodontic patients and found that

74.8% had at least 1 dental anomaly. Endo et al.[7] reported the high prevalence (8%-10%) of hypodontia (except third

molars) and lateral incisor agenesis of permanent teeth in

Japanese orthodontic patients.

Uslu et al.[3] found no statistically significant correlations

between having a dental anomaly and the type of

malocclusion, except having an impacted tooth or a short

blunt root. Zhu et al.[8] reported the prevalence of

supernumerary teeth by race, which was different between

the white population and the Turkish population [2].

The results of several studies, however, are conflicting. The

discrepancies in their results were attributed to racial

differences, variable sampling techniques, and different

diagnostic criteria. Racial differences were stressed as a

possible main explanation of this variation [4]. In spite of this variation, a common point between the different studies

was the unavoidable frequency of developmental dental

Original article

http://www.ijmhs.net/


anomalies in every community [2]. The purpose of this

study was to evaluate the prevalence and distribution of

dental anomalies, including other abnormalities in the pre-

treatment panoramic radiographs in a sample of Thai

orthodontic patients.

MATERIALS AND METHODS

The present study has been approved by Institutional

Review Board, Naresuan University. Pre-treatment digital

panoramic radiographs of a sample of Thai orthodontic

patients were retrospectively evaluated. All of the patients

had been referred for radiographic examination at Oral

Radiology Clinic, Dental Hospital, Faculty of Dentistry,

Naresuan University, and private dental clinic in

Phitsanulok, Thailand, between January, 2012 and October,

2014. All of panoramic radiographs were examined on 19.5

inches computer monitor (Samsung Syncmaster E2020X,

Samsung, Thailand) with resolution of 1600x900. The

selection criteria, as follows:

1. Patients with no history of tooth loss due to trauma or

extraction.

2. Patients without metabolic disorders or syndromes

affecting bone metabolism and/or tooth formation such

as Down’s syndrome, ectodermal dysplasia.

3. Patients without cleft lip and palate, dentofacial

deformities.

4. Patients with no history of previous orthodontic

treatment.

5. Good quality panoramic radiographs.

6. Complete root formation of all permanent teeth

appeared on panoramic radiographs (except third

molar).

Demographic data (age and sex) of the patients were record.

Panoramic radiographs were evaluated by a radiologist. The

following dental anomalies were assessed:

1. Number abnormalities: supernumerary tooth, missing

tooth

2. Size abnormalities: microdontia, macrodontia

3. Shape abnormalities: gemination, fusion,

concrescence, dens evaginatus, dens invaginatus,

taurodontism, dilacerations

4. Structural abnormalities: amelogenesis imperfecta,

enamel hypoplasia, dentinogenesis imperfect,

odontogenesis imperfect, dentinal dysplasia

5. Other findings: such as embedded tooth, ectopic

eruption, bifid root

Statistical analysis

Descriptive statistic (Statistical Package for Social Science:

SPSS) was used to evaluate the prevalence and distribution

of dental anomalies and other findings. Percentages and

means were also calculated.

RESULTS

The present study was performed for evaluation of

prevalence and distribution of dental anomalies and other

findings in the group of 638 pre-orthodontic treatment

patients, which composed of 167 males (26.2%) and 471

females (73.8%). Age ranged between 13 and 30 years

(mean 19.2 ± 3.39). The total prevalence and distribution of

dental anomalies is shown in Table 1.

In 638 patients, shape abnormalities were most found

(34.64%), followed by number abnormalities (15.83%) and

size abnormalities (7.52%) respectively. In addition, 252 of

638 patients (39.50%) exhibited one anomaly, 90 (14.11%)

patients showed two anomalies and 25 (3.92%) patients

displayed more than two anomalies (Table 2).

Number abnormalities

a)Hypodontia (Missing tooth)

It was found that 84 out of 638 patients had missing tooth

(18 males and 66 females, Table 1). Prevalence and

distribution of missing tooth is presented in Table 3. Except for third molar, the most common missing tooth was the

lower incisor (26.32%), followed by lower premolar

(24.81%) and upper incisor (19.55%) respectively. It was

found that missing tooth occurred in mandible (55.64%)

more often than in the maxilla (44.36%).

Among the hypodontia group, the percentage of patients

with one, two, three or more missing teeth were 60.71,

29.76, 2.38 and 5.95 respectively. The highest number of

congenitally missing teeth was 9 in only one patient (0.16%

of total number of patients).

b)Hyperdontia

Hyperdontia, including supernumerary tooth and mesiodens,

was seen in 17 patients. The most frequent hyperdontia was

upper left posterior tooth (8 patients, 36.35%), followed by

upper anterior teeth (5 patients, 22.73%), lower left posterior teeth (4 cases, 18.17%), lower right posterior teeth (3 cases,

13.65%) and upper right posterior teeth (2 cases, 9.10%)

respectively (Table 4).

Regarding the number of supernumerary tooth, the ratio of

male to female was 2.14 to 1, the ratio of upper to lower and

anterior to posterior teeth were 2.14 to 1 and 1 to 3.4

respectively.


Table 1: Prevalence and distribution of dental anomalies in study group

____________________________________________________________________________

Dental anomalies Male (%) Female (%) Total

____________________________________________________________________________

Number abnormalities:

Missing tooth 18 (2.83) 66 (10.34) 84 (13.17)

Supernumerary tooth 10 (1.56) 7 (1.10) 17 (2.66)

Size abnormalities:

Macrodontia 1 (0.155) 1 (0.155) 2 (0.31)

Microdontia 13 (2.04) 33 (5.17) 46 (7.21)

Position abnormalities:

Ectopic eruption 2 (0.31) 8 (1.25) 10 (1.56)

Shape abnormalities:

Fusion 1 (0.155) 0 (0) 1 (0.155)

Gemination 1 (0.155) 1 (0.155) 2 (0.31)

Taurodontism 4 (0.63) 17 (2.66) 21 (3.29)

Dilaceration 44 (6.90) 142 (22.26) 186 (29.16)

Dens invaginatus 0 (0) 7 (1.10) 7 (1.10)

Dens evaginatus 1 (0.155) 2 (0.31) 3 (0.47) Dentin dysplasia 0 (0) 1 (0.155) 1 (0.155)

Other findings:

External root resorption 1 (0.155) 0 (0) 1 (0.155)

Internal root resorption 1 (0.155) 0 (0) 1 (0.155)

Pulp stone 0 (0) 1 (0.155) 1 (0.155)

Total 97 (15.2) 286 (44.82) 383 (60.02)

_____________________________________________________________________________

Table 2: Frequencies of dental anomalies evaluated from panoramic radiograph

______________________________________________________________________________

Frequencies of anomalies Male (%) Female (%) Total (%)

______________________________________________________________________________

1 anomaly 86 (13.48) 166 (26.02) 252 (39.50)

2 anomalies 14 (2.19) 76 (11.92) 90 (14.11)

More than 2 anomalies 7 (1.10) 18 (2.82) 25 (3.92)

Total 107 (16.77) 260 (40.76) 367 (57.53)

______________________________________________________________________________

Table 3: Prevalence and distribution of missing tooth

______________________________________________________________________________

Location Male (%) Female (%) Total (%)

______________________________________________________________________________

Upper incisor 4 (3.01) 22 (16.54) 26 (19.55)

Upper canine 2 (1.50) 12 (9.02) 14 (10.52)

Upper premolar 5 (3.76) 14 (10.53) 19 (14.29)

Lower incisor 3 (2.26) 32 (24.06) 35 (26.32)

Lower canine 1 (0.75) 5 (3.76) 6 (4.51)

Lower premolar 6 (4.51) 27 (20.30) 33 (24.81)

Total 21 (15.79) 112 (84.21) 133 (100)

______________________________________________________________________________


Table 4: Prevalence and distribution of supernumerary tooth

_______________________________________________________________________________


_______________________________________________________________________________

Maxilla

Upper right posterior 1 (4.55) 1 (4.55) 2 (9.10)

Upper anterior 4 (18.17) 1 (4.55) 5 (22.73)

Upper left posterior 4 (18.17) 4 (18.17) 8 (36.35)

Mandible

Lower right posterior 2 (9.10) 1 (4.55) 3 (13.65)

Lower left posterior 4 (18.17) 0 (0) 4 (18.17)

Total 15 (68.18) 7 (31.82) 22 (100)

______________________________________________________________________________

Size abnormalities (macrodontia and microdontia)

Regardless of the third molar, macrodontia was found in

only 2 patients (0.31%, 1 male and 1 female). On the other

hand, microdontia was much more found in 46 patients

(7.21%). We found that in 66 teeth with microdontia, 65

(98.49%) were upper lateral incisor and 1 (1.51%) was

upper premolar. It was also observed that 20 out of 46

patients had bilateral peg-shaped upper lateral incisor (Table

5).

Table 5: Prevalence and distribution of microdontia

______________________________________________________________________________


___________________________________________________________________________

Upper lateral incisor 19 (28.79) 46 (69.70) 65 (98.49)

Upper premolar 1 (1.51) 0 (0) 1 (1.51)

Total 20 (30.30) 46 (69.70) 66 (100)

______________________________________________________________________________

Position abnormalities

Ectopic eruption was observed in 2 males and 8 females,

with a total prevalence of 1.56% (Table 1). All of the

patients in this group had ectopic eruption of upper canine,

the ratio of male to female was 1 to 4. Transposition was not

found in this study.

Shape abnormalities

Shape abnormalities were the most frequent dental anomalies observed in this study. Dilaceration had highest

prevalence (186 patients, 29.16%, Table 1). According to

Table 6, most of dilacerations occurred in upper premolar

(73 of 302 teeth, 24.17%), followed by lower molar (59

teeth, 19.53%) and upper incisor (58 teeth, 19.21%)

respectively.

Taurodontism was the second most frequent of shape

abnormalities (21 patients, 3.29%). Most of taurodontism

appeared in lower second molar (17 patients, 80.95%), the

ratio of male to female was 1 to 4.25. The other shape

abnormalities observed in this study including fusion

(0.155%), gemination (0.31%), dens invaginatus (1.10%),

dens evaginatus (0.47%) and dentin dysplasia (0.155%).

Other dental anomalies

Other radiographic findings of dental anomalies observed in

the present study were; 1 patient with internal root

resorption, 1 patient with external root resorption and 1

patient with pulp stone.

Other abnormalities

Out of 638 patients, other abnormalities were presented in Table 7. Embedded tooth was found in 38 patients (5.59%),

followed by bifid root of lower premolar (5 cases, 0.78%),

three roots of lower first molar (2 cases, 0.31%) and

odontoma of upper molar tooth (2 cases, 0.31%)

respectively.

In the present study, it was observed that dilacerations was

the most common dental anomalies (29.16%), followed by

missing tooth (13.17%), microdontia (7.21%), taurodontism

(3.29%) and supernumerary tooth (2.66%) respectively

(Table 8).


Table 6 Prevalence and distribution of dilaceration

____________________________________________________________________________


____________________________________________________________________________

Maxilla

Incisor 12 (3.97) 46 (15.24) 58 (19.21)

Canine 9 (2.98) 34 (11.26) 43 (14.24)

Premolar 10 (3.31) 63 (20.86) 73 (24.17)

Molar 5 (1.66) 10 (3.31) 15 (4.97)

Mandible Incisor 0 (0) 2 (0.66) 2 (0.66)

Canine 2 (0.66) 7 (2.32) 9 (2.98)

Premolar 8 (2.65) 35 (11.59) 43 (14.24)

Molar 26 (8.61) 33 (10.92) 59 (19.53)

Total 72 (23.84) 230 (76.16) 302 (100)

______________________________________________________________________________

Table 7: Other abnormalities on panoramic radiograph among the study subjects

______________________________________________________________________________

Abnormalities Cases (%) Location

______________________________________________________________________________

Embedded tooth 38 (5.59) upper and lower incisors upper and lower premolars

lower molars Bifid root 5 (0.78) lower premolars Three root 2 (0.31) lower molars

Odontoma 2 (0.31) upper molars ______________________________________________________________________________

Table 8: Prevalence order of dental anomalies

______________________________________________________________________________

Order Dental anomalies Cases (%)

___________________________________________________________________________

1 Dilaceration 186 (29.16)

2 Missing tooth 84 (13.17)

3 Microdontia 46 (7.21) 4 Taurodontism 21 (3.29)

5 Supernumerary tooth 17 (2.66)

____________________________________________________________________________

DISCUSSION

9-11 age group showed more suffering from atopy

compared to age group 12-14 year old. These result were

consistent with the Although several studies have

emphasized the prevalence and distribution of dental

anomalies in orthodontic patients, their conflicting results

can be explained by racial differences, sampling techniques and diagnostic criteria. They could also be explained by

local environment influences and nutrition [2,4]. Congenital

anomalies of the teeth often appear together with

craniofacial discrepancies generating complicated

therapeutic problems [9]. Environmental factors could have

more influence on the prevalence of dental anomalies than

racial factors in every population [10]. Although defects in

certain genes are considered the main causes, etiologic events in the pre- and postnatal periods have also been

blamed for dental anomalies [11]. Influences on teeth may

begin before or after birth, and primary and permanent teeth

can both be affected [12].

The present study was performed by evaluation of

panoramic radiograph in pre-orthodontic treatment patients.

It was found that 39.50% of 638 patients (may be implied

that every 2-3 Thai orthodontic patients) had at least one

dental anomaly. Uslu et al.[3] reported 40.3% of 900


Turkish patients with one dental anomaly, whereas

Thongudomporn & Freer[6] reported 74.78% of 111

patients with the same condition. To the author’s

knowledge, there has been only one study of the prevalence

and distribution of dental anomalies in Thai population,

which was performed in 570 patients (124 males and 446 males) [13]. However, their results were different from this

study. In addition, differences in the prevalence and

distribution of dental anomalies were observed between the

present study and previous studies in various races as

follows.

Hypodontia is one of the most common dental anomalies in

orthodontic patients. The prevalences of hypodontia in

orthodontic patients were different in various group of

population. It ranges from 2.6% in Turkey[2], 5.5% in

Mexico[14], 6.3% in Brazil[15], 8.5% in Japan[7], 11.1% in

Korea[16], 13.7% in Thai (this study) to 14.7% in Hungary

[17].

Prevalence of hypodontia in this study was 13.7% 638

patients, which was lower than that of the results of

Kositbowornchai et al.[13] (26.4% of 570 Thai patients). Difference region and ethnic of population may be

explained for the different results. In our study, the most

commonly missing tooth was lower incisor (26.32%),

followed by lower premolar (24.81%) and upper incisor

(19.55%). The second and third most common missing teeth

of our study were different from Kositbowornchai et al.[13]

(upper lateral incisor and lower second premolar

respectively). We also found that most common missing

tooth in our study was different from the others; upper

lateral incisor in Turkish[2], Indian[4], Mexican[14] and

Brazilian[15], and lower second premolar in Japanese [7]. However, our result was in accordance with study of Chung

et al.[16] in Korean, for the two most common missing

teeth.

Dental anomalies such as tooth agenesis are frequently

associated with other anomalies such as microdontia,

delayed dental development, and some discrete tooth

ectopia, perhaps because a certain genetic mutation causes a

series of different phenotypic expression [18]. Mutation in

genes such as MSX, PAX 9 or TGFA are reported to cause

hypodontia in different racial groups [19].

The prevalence of supernumerary tooth is less common than

missing tooth, and is differ between races. Uslu et al.[3]

reported the prevalence of 0.3% in Turkey, Gupta et al.[4]

reported the prevalence of 0.62% in India, Zhu et al.[8] found the prevalence of hyperdontia ranged from 1% to 3%

among the white population. A significant difference was

also observed between the present study (2.66%) and the

study by Kositbowornchai et al.[13] (13.17%) in Thai

population. This may be explained by the different part

living (North and Northeast parts of Thailand), local

environment, nutrition, inclusion criteria, diagnostic criteria,

and study design.

In the present study we found that the most common

supernumerary tooth was upper left posterior tooth (36.35%,

8 of 22 teeth). Our result was different from others, which

reported that the most common supernumerary teeth was

upper anterior tooth.[3,4,6,13] We found mesiodens in 5 of 638 patients (0.78%). The prevalence of mesiodens in

orthodontic patients ranged between 0.3% to 1.8%[2,6],

which is not significantly different from the general

population (0.15%-1.9%) [20].

Macrodontia is a rare abnormality of teeth and very much

less common than microdontia [2]. In the present study, we

found 0.31% of macrodontia and 7.21% of microdontia. The

most frequently found of microdontia was upper lateral

incisor (98.49%), which was in agreement with other studies

[2,6,13]. The prevalence of microdontia had been reported to increase over time [10]. This was attributed to the rate of

evolution, local environmental factors and criteria in

selecting the study groups [2].

Transposition is a less common anomaly which always

found in permanent teeth (prevalence 0.3%-0.4%). It was

reported that the upper teeth always had transposition

including: canine and premolar, canine and lateral incisor,

lateral and central incisor [21]. Transposition may occur

with other abnormalities such as aplasia, peg-shaped lateral

incisor and deciduous teeth retention [22]. Our study result,

in agreement with Yilmaz et al.[21], the most frequently

found transposed teeth were upper canine and premolar.

However, Kositbowornchai et al.[13] reported that canine and first premolar were the most common found tooth

transposition. Even though studying in the same race (Thai),

the results were different.

We also observed ectopic eruption of upper canine in 7

patients without statistically significant difference between

males and females.

Shape abnormalities were the most common dental

anomalies in the present study (34.64%, 221 of 638

patients). We found that the most frequently found shape

abnormality, and also the most common dental anomaly in

this study, was dilaceration (29.16%, 186 0f 638 teeth). The

prevalence of dilaceration in our study was higher than

others (1.8%-3.78%) [3,6,23]. The most common

dilaceration in our study was upper premolar (24.17%), followed by lower molar and upper incisor respectively.

There was no reported of dilaceration in the other study in

Thai population [13]. The etiology of dilaceration resulting

from an altered position of the tooth crown relative to the

developing root and root sheath [24].

There also many factors that cause dilaceration including

scar formation, primary tooth germ anomaly, facial clefting,

advanced root canal infections, ectopic development of

tooth germ and lack of space, anatomic structure, cyst,

tumor or odontogenic hamartoma, orotracheal intubation,

mechanical interference with eruption, tooth transplantation,

extraction of primary tooth and hereditary factors [25].

Tooth root dilaceration can increase the treatment difficulty by impeding dental implant placement, root apex access

through the root canal system, tooth extraction, affect crown

root ratios/ periodontal support, orthodontic anchorage and

root positioning within the bone [26].

The definition of root dilaceration varies in the relevant

literature and depends on the criteria set by each author.

Some authors describing dilaceration as a 90º or greater root

deflection in relation to the tooth or root axis. Others

consider a tooth dilacerated when its apical deviation is

equal or exceeds 20º in relation to the normal tooth axis

[27]. The high prevalence of dilaceration in our study

comparing with the others can be explained by different

diagnostic criteria. We considered a tooth dilacerated when


its apical deviation is equal or exceeds 20º in relation to

normal tooth axis as defined by Chohayeb [27]. Thus, this

criteria may be the possibility reason of the high prevalence

in the present study.

The second most shape abnormality found in our study was

taurodontism (3.29%), observed mostly in lower second

molar. Our result was not in accordance with Darwazeh et

al. who reported the most common found taurodontism in upper second molar. This dissimilarity might be related to

racial variations. Prevalence of taurodontism was not

observed in the study of Kositbowornchai et al [13].

Dens invaginatus was found 1.1% in our study, most

frequently in upper lateral incisor (57.1%), in agreement

with Hülsmann [28]. Although dens invaginatus is not

common, there can be severe difficulties related to tooth

anatomy during endodontic treatment [23,28]. Therefore,

orthodontists should be aware of this anomaly in making

decisions about extractions.[3] On the other hand, dens

invaginatus is not considered a risk factor for apical root

resorption during orthodontic tooth movement, although

invaginated teeth have malformed roots more often than

noninvaginated teeth [29].

We found dens evaginatus in only 0.47% of the patients.

Dens evaginatus occurs most commonly in people of

Mongoloid origin, with an average incidence of 2.2% [30].

Uslu et al.[3] reported higher prevalence of dens evaginatus

(6.2%) in Turkish. Early diagnosis of dens evaginatus is

important so that loss of vitality during orthodontic therapy

can be prevented, and treatment alternatives can be

considered. In the orthodontic treatment plan, extraction of a

tooth involving dens evaginatus might be considered so that

the anomalous tooth, rather than an unaffected one, is

extracted [3].

The very low rates of internal and external root resorptions,

and pulp stone (0.155% for each) were observed in the

present study. There also hardly found in other reports.

Regardless impacted third molars, we found embedded

tooth, bifid root, three roots and odontoma. Surgical

management of embedded tooth or odontoma is depend on

decision of orthodontist and/ or oral surgeon.

CONCLUSION

Dental anomalies can be detected easily by a careful

evaluation of routine pretreatment diagnostic tool such as

panoramic radiograph. Dilaceration was the most common

anomaly in the present study. The prevalence and

distribution of dental anomalies are different between the

parts of Thai orthodontic patients and between the races.

The further studies of molecules and molecular mechanisms

operating in the craniofacial region during tooth

development are important in finding out the causes of

them.

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*Corresponding author: Weeraya Tantanapornkul

E-Mail: [email protected]

mailto:[email protected]

prevalence/distribution of dental anomalies in thai orthodontic patients

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