|Year : 2017 | Volume
| Issue : 3 | Page : 141-147
A study on prevalence, complications, and possible etiologic factors of supernumerary teeth in 6–12-year-old schoolchildren of Rohtak, India
Seema Gupta1, PS Praveen Kumar2
1 Department of Pedodontics and Preventive Dentistry, Yamuna Institute of Dental Sciences and Research, Yamunanagar, Haryana, India
2 Department of Dentistry, Mysore Medical College and Research Institute, Mysore, Karnataka, India
|Date of Web Publication||7-Aug-2017|
P S Praveen Kumar
Department of Dentistry, Mysore Medical College and Research Institute, Mysore, Karnataka
Source of Support: None, Conflict of Interest: None
Background: A study on prevalence, complications, and possible etiological factors of supernumerary teeth in 6–12-year-old schoolchildren of Rohtak, India. Aim: This study aimed to study the prevalence of supernumerary teeth in Rohtak district, Haryana, India and elucidate the possible etiological factors for their origin and the type of malocclusion caused by their presence. Materials and Methods: Two thousand and sixty school-going nonsyndromic children of 6–12-year age were examined for the presence of supernumerary teeth and referred to the Department of Pedodontics and Preventive Dentistry. Detailed history, clinical and radiographic examinations were done. Chi-squared test was used for statistical analysis. Results: Ninety-four supernumerary teeth were found in 81 children. All supernumerary teeth were found in maxilla. Most of these teeth were erupted, conical, and in the midline. Labial displacement of adjacent teeth was most commonly seen. Birth order of these children was mostly 2nd or 3rd, and majority of them belonged to the Jat community and were born at home by normal delivery. Conclusions: The present study emphasizes the necessity for early detection and appropriate management of supernumerary teeth. We suggest the development of further approaches including family studies to estimate the importance of genetic and possible environmental factors to attain a more precise knowledge of the etiology of hyperdontia.
Keywords: Complications, etiology, prevalence, supernumerary teeth
|How to cite this article:|
Gupta S, Praveen Kumar P S. A study on prevalence, complications, and possible etiologic factors of supernumerary teeth in 6–12-year-old schoolchildren of Rohtak, India. Indian J Dent Sci 2017;9:141-7
|How to cite this URL:|
Gupta S, Praveen Kumar P S. A study on prevalence, complications, and possible etiologic factors of supernumerary teeth in 6–12-year-old schoolchildren of Rohtak, India. Indian J Dent Sci [serial online] 2017 [cited 2018 Feb 25];9:141-7. Available from: http://www.ijds.in/text.asp?2017/9/3/141/212399
| Introduction|| |
Hyperdontia is a mammalian developmental anomaly characterized by the presence of extra teeth in addition to the teeth of normal eruption series. It is considered to be a multifactorial inheritance disorder originating from hyperactivity of dental lamina.
Based on the location in the dental arch, a supernumerary tooth can be categorized into three typesesiodens, distomolar, or paramolar. In permanent dentition, it may be of conical, tuberculate, supplemental, or odontoma type. The incidence of supernumerary teeth is about 0.15%–3.8% on a population basis., Most of the studies have shown that maxillary midline supernumerary teeth are the most common type, followed by maxillary lateral incisor.,
They can be asymptomatic for years or may cause complications such as impaction, delayed eruption of adjacent teeth, crowding, midline diastema, cystic formation, and root resorption of adjacent teeth. Therefore, early diagnosis, evaluation, and appropriate treatment of supernumerary teeth are essential.
The bulk of information in the literature seems to concentrate on prevalence, complications, and peculiar features encountered in isolated cases. Despite the burgeoning literature on supernumerary teeth on above characteristics, none has attempted to include the possible etiological factors for their origin in the study. The present study has been planned to gather a comprehensive data regarding the prevalence of supernumerary teeth in Rohtak district, Haryana state of India and elucidate the possible etiological factors for their origin and the type of malocclusion caused by their presence.
| Materials and Methods|| |
This cross-sectional study was approved by the Institutional Ethical Committee. The district of Rohtak is located in South-East of Haryana state in Northern India. This descriptive analysis investigated 2060 nonsyndromic children (1240 boys and 820 girls) whose age ranged from 6 to 12 years. These children were selected randomly from both public and private schools, which were included based on feasibility of approach. A formal permission was taken from administrative authorities before examination.
Clinical examination of oral cavity was done under natural daylight with the help of mouth mirror and probe. Dentition was examined carefully for any supernumerary teeth. Children were selected on the basis of the following criteria: (a) presence of any supernumerary tooth in anterior or posterior region of mouth, (b) presence of any malocclusion (which may be caused by the presence of an impacted supernumerary tooth) such as midline diastema and delayed eruption of permanent teeth, and (c) where presence of any supernumerary tooth was suspected by inspection and palpation of palate, maxillary, and mandibular alveolar processes.
Parents of all the selected children were contacted, explained about the problem, and told to report to the Department of Pedodontics and Preventive Dentistry. These parents were then interviewed, and a detailed history was taken. Patients' data included information about their gender, ethnic group, and birth order. Information was obtained from the mothers of these children regarding their age at the time of conception, consanguinity of marriage, any complications/medications consumed/irradiation during pregnancy, type and place of delivery, and finally history of the presence of a similar abnormality in any other member of the family. Information of confidentiality was given to the parents, and a written informed consent form was obtained.
After this, clinical and radiographic examinations were performed by a single observer to study the characteristics of supernumerary teeth. Radiographic examination included periapical radiographs of the involved region. In case of any doubt regarding the position, as in case of impacted teeth, two periapical radiographs were taken from different horizontal angulations, and Clark's rule was applied to diagnose the sagittal position of supernumerary tooth. Wherever required, periapical radiographs were supplemented with maxillary occlusal radiographs. Further, study models were made to study the type of malocclusion caused by the presence of supernumerary teeth. Characteristics of supernumerary teeth were confirmed upon surgical removal of these teeth.
All the information and data were compiled and statistically analyzed using Chi-square test. P < 0.05 was considered statistically significant.
| Results|| |
Out of 2060 children, supernumerary teeth were found in 81 children (60 males and 21 females), prevalence being 3.93%. The sex ratio was 2.85 in favor of males. Most of the patients (68 cases, 84%) had a single supernumerary tooth; rest (13 cases, 16%) had two supernumerary teeth each. In none of the cases, >2 supernumerary teeth were found. An average number of supernumerary tooth per patient was 1.16.
Regarding the distribution of patients by ethnic group, most of the children belonged to Jat community (41 cases, 50.6%), followed by Punjabis (16 cases, 19.8%), backward classes (9 cases, 11.1%), scheduled castes (7 cases, 8.6%), Pandits (6 cases, 7.4%), and Baniyas and Rajputs (1 each, 1.2%).
When the birth orders of children, i.e., the sequence of the child in the family were studied, 26 children had 2nd and 3rd birth rank each (32.1% each), followed by 24 firstborn children (29.6%); 4 children (4.9%) of 4th birth order and only 1 child (1.2%) of 5th birth order. Maternal age was 15–20 years in 9 cases (11.1%), 21–25 years in 26 cases (32.1%), 26–30 years in 33 cases (40.7%), and 31–35 years in 13 cases (16.0%).
The marriage of the parents was consanguineous in 8 cases (9.8%) out of all the 81 children. Mothers of these children were asked if they suffered from any prolonged illness and consumed any kind of medications during the pregnancy. Most of the mothers did not give any relevant drug history. Only in four cases (4.9%), mothers could recollect consuming some medications during the pregnancy. In addition, none of the mothers reported any sort of irradiation during pregnancy.
The children were delivered by normal vaginal delivery in 77 cases (95.06%). In 4 cases (4.9%), the children were delivered by cesarean section. In none of the cases, mothers reported any complication during the delivery of the child. All the children were delivered at term. None of the mothers reported pre- or post-term delivery. Delivery was conducted at home in 54 cases (66.7%) and in rest 27 cases (33.3%), at hospitals.
In 7 children (8.6%), there was a history of the presence of a similar type of tooth in another member of the family.
Variables related to supernumerary teeth and their relation
The most common type of supernumerary teeth observed were mesiodens (88 teeth, 93.6%) followed by supernumerary lateral incisors (6 teeth, 6.4%), thus making a total of 94 supernumerary teeth. All the supernumerary teeth were found in maxilla. None were found in the mandible.
The most commonly observed morphology was conical (74 teeth, 78.7%), followed by tuberculate (15 teeth, 15.9%) and supplemental (5 teeth, 5.3%).
Of all the 94 teeth, 15 (15.9%) supernumerary teeth were impacted and 79 (84.0%) teeth were erupted. Five patients had two erupted supernumerary teeth each and 61 had a single erupted supernumerary tooth. In 8 patients, there was the presence of both an impacted, and an erupted supernumerary tooth.
Eighty-seven teeth (92.5%) were in normal vertical orientation, followed by six (6.4%), inverted teeth and one tooth (1.1%) with horizontal orientation. Show the various types of supernumerary teeth observed in the present study.
Of the 94 supernumerary teeth, 73 mesiodens were erupted, whereas 15 mesiodens were impacted. All the six supernumerary lateral incisors were erupted, all within the dental arch. Out of all the 79 erect, erupted supernumerary teeth, 69 were conical, 12 were tuberculate, and 5 were supplemental in morphology. Of the six inverted, impacted supernumerary teeth, four were conical and two were tuberculate. The only horizontally impacted supernumerary tooth was conical in morphology. [Table 1] and [Table 2] show the relation between morphology of supernumerary teeth and their eruption status and orientation, respectively.
|Table 1: Relation between morphology of supernumerary teeth and eruption status*|
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|Table 2: Relation between morphology of supernumerary teeth and orientation*|
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Most of the supernumerary teeth were in palatal position (60 teeth, 63.8%) with respect to the dental arch, 32 teeth (34.0%) were within the dental arch, and 2 teeth (2.1%) were in the labial position. [Table 3] shows the relation between morphology and position of supernumerary teeth. [Table 4] shows the relation between position and eruption status of supernumerary teeth.
|Table 3: Relation between morphology of supernumerary teeth and position*|
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|Table 4: Relation between position and eruption status of supernumerary teeth*|
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Root development was complete in 69 supernumerary teeth (73.4%) and incomplete in 25 teeth (26.6%). [Table 5] shows the relation between root development and eruption status of supernumerary teeth.
|Table 5: Relation between root development of supernumerary teeth and eruption status*|
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The complications caused by the presence of supernumerary teeth were studied both clinically and radiographically. [Table 6] shows the complications caused by the presence of supernumerary teeth in the participants examined.
[Table 7] shows the relation between morphology of supernumerary teeth and the complications caused by them. Statistical analysis using Chi-square test revealed a very highly significant difference in the complications caused by the two major types of supernumerary teeth observed in this study, i.e., conical and tuberculate. The conical teeth were found to cause displacement of adjacent teeth in most cases whereas the tuberculate teeth usually delayed the eruption of permanent teeth.
|Table 7: Relation between morphology of supernumerary teeth and their complications*|
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| Discussion|| |
In the present study, children from 6 to 12 years of age, i.e., those in a mixed dentition stage were included in the study. This was taken because supernumerary teeth are found infrequently in primary dentition with prevalence ranging from 0.03% to 1.9%.,, Furthermore, most primary supernumeraries erupt normally because the presence of interdental spaces allows for the uneventful eruption of the extra tooth. Many such teeth exfoliate without being recognized as supernumeraries.
Hyperdontia is considered a multifactorial developmental anomaly, where both genetic and environmental factors come into play. Hitherto, the factors which may predispose to the development of hyperdontia have not been discussed much in the literature. Therefore, a list of possible predisposing factors was made and evaluated. The first phase of the study encompassed the gathering of information regarding these variables.
Ethnic factors must be taken into consideration when evaluating processes affecting the dentition. In the present study, most of the children belonged to Jat community, which constitutes the major population of district Rohtak of Haryana state. Townsend et al. also speculated that supernumerary teeth, notably the addition of eumorphic teeth, showed appreciable ethnic variation and they tended to cluster in families.
Garn et al. suggested that dental development may also be influenced by maternal environment. Hence, maternal age and birth order of the child were taken as indirect measures of intrauterine conditions, as in a study by Bailit and Sung. The mean birth order was 2.16 ± 0.95 and the mean maternal age was 26.03 ± 4.54 years.
Nature of marriage of the parents was studied considering the deleterious effects of consanguinity on the offspring. Consanguineous marriages were reported in 9.8% cases.
Environmental factors, including maternal influences such as hypothyroidism, diabetes, hypertension, and smoking may affect the teeth. Irradiation  and drugs such as thalidomide  during pregnancy have been reported to be the major environmental factors associated with anomalies of tooth number and size. Similarly, dental defects may also be caused by complications of pregnancy such as traumatic delivery, cesarean section, birth asphyxia, and cerebral injuries. In our study, maternal drug history during pregnancy was positive only in four cases (4.9%). However, the exact nature of the medication could not be obtained in any of the cases, as all of them belonged to rural locations with a minimum level of education. In addition, none of the mothers reported any sort of irradiation during pregnancy or any complications during delivery. Since most of the children belonged to rural locations, they were delivered at home by trained nurse midwives, generally at term. Delivery of the child was designated as preterm only if the child was born before the 37th completed week of pregnancy as specified by the World Health Organization definition.
Brook  reported much higher frequencies in the first-degree relatives of the probands than in the general population, suggesting a significant genetic component in the etiology. In our study, in 8.6% cases, history of the same abnormality having been seen in other members of the family was obtained, to further corroborate the belief that hyperdontia has a hereditary tendency to occur.
The sex ratio was 2.85 in favor of males, a value that falls between the sex ratio reported for Caucasian populations. Most of the children in our sample were boys (1240 boys and 820 girls) though this was entirely a random occurrence. Owing to the sex predominance of males over females, which has been a constant observation in almost all the studies related to supernumerary teeth, Bruning et al. have proposed the possibility of sex-linked inheritance for the etiology of this anomaly. Niswander and Sujaku  theorized that hyperdontia might be associated with an autosomal recessive gene with lesser penetrance in females. However, the exact mode of transmission is still unknown. According to Alvesalo, the differential effects of the X and Y chromosomes on cell function and proliferation, especially that of the Y chromosome on cell proliferation, may be related to the sexual dimorphism observed in tooth number.
The etiological basis of extra teeth is poorly understood in human populations; however, the mouse provides a useful model system to investigate the complex genetics of tooth development. Indeed, many of the molecular signaling pathways known to be involved in normal development of the tooth germ can also give rise to additional teeth if inappropriately regulated. These include components of the Hedgehog, fibroblast growth factor, Wnt, tumor necrosis factor, and bone morphogenetic protein families, which provide a useful resource of candidate genes that may potentially play a role in human supernumerary tooth formation. A more detailed investigation of the genetic pattern of individuals with supernumerary teeth in comparison to those with normal complement of teeth can be carried out. This could help in understanding the underlying genetic mechanisms. In addition, a larger sample size would probably shed more light on the role of possible environmental factors.
In the second phase of the study, the epidemiological characteristics of supernumerary teeth were examined, with an analysis of the associated clinical-eruptive complications. The incidence of supernumerary teeth obtained in this work (3.93%) is slightly higher than the range of 0.15%–3.8% reported in literature,, which may be due to racial variations, difference in ages of participants, and examination methods. Clinical surveys without the use of radiographs result in underestimation of the incidence because unerupted teeth escape detection. In the study conducted by MacPhee, only visual examination of children was carried out, which may be the reason behind a lower incidence (0.3%), despite a higher sample size (4000 children). Other studies involving panoramic examination would underestimate the prevalence of supernumerary teeth because panoramic radiographs exhibit some distortion or burned areas, especially in the anterior midline region. In the present study, both clinical and radiographic examinations of oral cavity were done so that both erupted and impacted supernumerary teeth could be recorded. In addition, the periapical radiographs were supplemented by maxillary occlusal views, wherever required, as the technique for taking such films is well tolerated by children.
In the present study, the occurrence of multiple supernumerary teeth (>3) was not found, as in a few previous studies., Furthermore, all the supernumerary teeth were found in maxilla, in agreement with the previous studies. Supernumerary teeth were most commonly observed near the maxillary midline region (93.6%), followed by lateral incisor region (6.4%), in accordance with the previous studies., In the present study, the term mesiodens has been used to refer to supernumerary tooth of any morphology located near the midline of upper arch, as cited by Gallas and García, to maintain uniformity and avoid confusion.
The morphology of supernumerary teeth was described according to the classification given by Hattab et al. The most commonly observed shape was conical (78.7%), followed by tuberculate (15.9%) and supplemental (5.3%) similar to previous reports.,
Regarding the eruption status, 15.9% supernumerary teeth were impacted and 84.0% were erupted, similar to the study by Humerfelt et al.
It was difficult to assess the position of impacted teeth accurately from radiographs alone. The position of these teeth was hence confirmed after their extraction. The palatine position of supernumerary teeth predominated over others in the present study, as in the previous studies.,,, The predominant palatine position may be because lip inhibits labial repositioning, and thick dense palatal bone possibly inhibits the eruption of these teeth in molar region.
The orientation of supernumerary teeth was erect in most of the cases, followed by a few inverted teeth, i.e., crown pointing toward nares and only one tooth with horizontal orientation. This supports the results of many studies., It is important to study the extent of root development of supernumerary teeth, especially when their surgical removal is contemplated. The root formation of supernumerary teeth was complete in most of the cases. However, in the study by Hurlen and Humerfelt, the teeth with incomplete root development were more in number than those with complete root development.
The most commonly observed complication in the present study was labial displacement of adjacent teeth, followed by delayed eruption of permanent teeth, as in a few previous studies. The explanation of displacement may be that the forming crown of the permanent tooth might have been displaced from its normal path of development by the supernumerary tooth growing alongside it on the tooth band or dental lamina. Diastema formation with or without displacement of adjacent teeth was also observed in a few cases. Diastema formation may also be a normal feature of early mixed dentition stage. Hence, only those cases were included where it was judged that the diastema formation was due to the presence of supernumerary tooth and not a self-correcting anomaly. Root resorption of adjacent teeth and no specific complications were observed in four cases each. Root resorption of adjacent permanent teeth was radiographically evaluated by identifying the outline of the lamina dura, periodontal ligament space, and root surface.
Formation of cysts and tumors was not observed in this study, in accordance with some earlier studies. This could be attributed to the young age of the patients who composed the sample, and the fact that supernumerary teeth had been diagnosed and extracted before cystic transformation of the follicle could take place.
Most of the conical teeth and tuberculate teeth were erupted, and all the five supplemental teeth were erupted. However, the difference between the eruption status of different types of supernumerary teeth was not statistically significant. In our study, the eruption rates of conical and tuberculate teeth were found to be almost similar, as in the study by Liu. However, many authors have reported conflicting results also.,
In the present study, all the erupted teeth were normally oriented, but not all the normally oriented teeth had erupted. All the inverted and transversely oriented teeth were unerupted. This is in accordance with the study conducted by Liu  and Rajab and Hamdan.
Considering the results obtained by statistical analysis, it could be concluded that the erupted and impacted teeth differed significantly in their position in the dental arch and root development. This complements the fact that most of the erupted supernumerary teeth had fully developed roots, similar to the results of a study by De Oliveira Gomes et al.
There was a statistically significant difference in the position of various types of supernumerary teeth. In the study by Foster and Taylor, all the tuberculate teeth were found palatal to the upper central incisors. In addition, majority of conical teeth appeared to be between the upper central incisors.
Statistical analysis revealed no significant difference between the root development of different types of supernumerary teeth. This is in contradiction with the results by Foster and Taylor  and De Oliveira Gomes et al., who found a highly significant difference in the degree of root formation of these two types of supernumerary teeth. This may be attributed to difference in the parameters studied.
In the present study, statistical analysis revealed a very highly significant difference in the complications caused by the two major types of supernumerary teeth observed in this study, i.e., conical and tuberculate. The conical teeth were found to cause displacement of adjacent teeth in most cases whereas the tuberculate teeth usually delayed the eruption of permanent teeth. This is in agreement with the previous reports. This difference in the two types of supernumerary teeth is especially important when treatment is considered. The tuberculate type of tooth considerably delays the eruption of upper central incisor and should be removed as soon as possible if the central incisor is to erupt in a reasonable time. The conical type, unless it is causing malpositioning or crowding of central incisors, may sometimes be left alone, especially if it is high up and inverted.
| Conclusion|| |
The results of the present study underline the necessity for early detection and appropriate treatment of these teeth. It should be prudent to adopt a routine radiographic screening of maxillary anterior region at early mixed dentition stage. The presence of an erupted supernumerary with or without the associated symptoms of bodily displacement, midline diastema, torsiversion, or delayed eruption should spur the clinician to suspect the existence of unerupted supernumeraries. Pediatric dentists must be capable of recognizing intrinsic and extrinsic factors, which can interfere in the developmental stages of teeth, leading to anomalies such as hyperdontia. Previous studies focused only on clinical, radiological, and surgical or surgical-orthodontic aspects of the treatment of supernumerary teeth. In the present study, a list of factors laying emphasis on both environment and genetics as possible factors in the etiology of hyperdontia was evaluated. This might be an initial step toward undertaking more specific genetic and family studies for understanding the etiological mechanisms of supernumerary teeth.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]