International Journal of Medical and Health Sciences

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1 International Journal of Medical and Health Sciences Journal Home Page: ISSN: Original article Prevalence and Distribution of Dental anomalies in Thai Orthodontic Patients Weeraya Tantanapornkul 1* 1 Department 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, 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 Int J Med Health Sci. April 2015,Vol-4;Issue-2 165

2 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 pretreatment panoramic radiographs in a sample of Thai orthodontic patients. 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. 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, 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 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. Int J Med Health Sci. April 2015,Vol-4;Issue-2 166

3 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) Int J Med Health Sci. April 2015,Vol-4;Issue-2 167

4 Table 4: Prevalence and distribution of supernumerary tooth _ Location Male (%) Female (%) Total (%) _ 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 Location Male (%) Female (%) Total (%) 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 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). Int J Med Health Sci. April 2015,Vol-4;Issue-2 168

5 Table 6 Prevalence and distribution of dilaceration Location Male (%) Female (%) Total (%) 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 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 Int J Med Health Sci. April 2015,Vol-4;Issue-2 169

6 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 Int J Med Health Sci. April 2015,Vol-4;Issue-2 170

7 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]. 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