Dental anomalies in permanent teeth and the associated etiological factors among fifteen years-old students in Basrah city \ Iraq

Background: Dental anomalies of teeth are major issue that contributes to dental problems encountered in general practice. The aim of this study is to measure the prevalence of dental anomalies and the associated etiological factors among 15 years old students in Basrah city –Iraq. Materials and methods: The total sample composed of 1000 students (435 males and 565 females) from urban area selected randomly from different high schools in the city. Diagnosis of dental anomalies were recorded by present or absent, diagnosis and recording of enamel defects were done according to the criteria of WHO (1997). Results: The prevalence of hypodontia was 4.6%, Females have higher prevalence than males (5.8% females and 3.0% males), talon cusp prevalence was 37.0% (males 38.6% and females 35.8%), the prevalence of microdontia was 1.4% (males were equal to females 1.4%), the prevalence of supernumerary teeth, fusion, macrodontia and gemination was 0.8%, 0.7%, 0.1% and 0.1% respectively. The prevalence of enamel defects was 30.5%, demarcated opacities prevalence was 23.8%, it is the most prevalent type of enamel defects (males 20.5% and females 26.4%) followed by diffuse opacities 9.1% then enamel hypoplasia 0.4%. Conclusion: This study revealed that secondary school students have dental anomalies, some of them with high prevalence, while other has very low prevalence.


INTRODUCTION
Dental anomalies of teeth are not uncommon problem, anomalies of teeth number, shape and structure occur due to abnormal events in the embryological development of teeth that may be resulted from environmental and genetic factors during the morphodifferentiation or histodifferentiation stages of tooth development (1) .
Anomalies of teeth shape include: fusion that can be defined as joining of two developing teeth germs, resulting in a single large tooth structure (2) .
Gemination defined as the attempt of tooth bud to divide, that will resulted in the formation of tooth with a bifid crown and common root with root canal (3) .
Talon cusp is a well-defined accessory cusp project from the cingulum or cemento-enamel junction to the incisal ridge of the upper or lower anterior teeth in both the deciduous and permanent dentitions (4) .
Microdontia defined as a tooth that is much smaller than normal average size while macrodontia defined as a tooth that is much larger than normal average size (5) .
Anomalies of the number of teeth include: hypodontia and supernumerary teeth, hypodontia defined as congenital lack of teeth that results from disturbances during tooth development in early stages (6) .Supernumerary teeth can be defined as extra teeth occurring in dental arch, more than twenty in deciduous dentition or more than thirty-two in the permanent dentition (3) .
Enamel defects can be defined as any alteration that results from wide disturbances during the process of odontogenesis, these defects include diffuse opacities, demarcated opacities and enamel hypoplasia (7) .
The etiological factors for the development of dental anomalies that had been studied include tooth trauma, deciduous tooth extraction, previous surgery in the jaw, low birth weight and systemic diseases (8) (9) .The aim of this study was to measure the prevalence of dental anomalies and find an association with the etiological factors.

MATERIALS AND METHODS
This study was conducted among high school students during the period from the middle of November 2014 till the beginning of April 2015 in Basrah city, Iraq.
In this study the sample consist of 1000 students aged 15 years old, the schools were randomly selected, and they were distributed in different geographical location in Basrah city.

Vol. 29(1), March 2017
Dental anomalies in Pedodontics, Orthodontics and Preventive Dentistry 149 Diagnosis of dental anomalies were recorded by present or absent, diagnosis and recording of enamel anomalies were done according to criteria of WHO 1997, questionnaire papers were distributed to the students to answer questions related to the etiological factors, these questions include if the students had exposed previously to tooth trauma, deciduous tooth extraction, previous surgery in the jaw and also were asked to try to locate the tooth or if they had low birth weight and any systemic disease .Data entering and analysis was performed using SPSS version 21 computer software (Statistical Package for Social Science) in association with Microsoft Excel.The tests that were used in this study include: 1. t-test.

RESULTS
Table (1) illustrates the distribution of the sample by gender, the sample consist of 435 males (43.5%) and 565 females (56.5%).
Table (2) demonstrates the total prevalence of the selected anomalies among the sample.
Table (3) shows the relationship between tooth trauma and dental anomalies which was nonsignificant statistically.
Table (4) illustrates the relationship between deciduous tooth extraction and dental anomalies by using Chi-square test, the results were nonsignificant statistically except the relationship between deciduous tooth extraction with demarcated opacities and any type of enamel defects which was significant statistically (p <0.001, p =0.022).
Table (5) shows the relationship between previous oral surgery and dental anomalies which was non-significant statistically.
Table (6) demonstrates that there is no significant relationship between low birth weight and dental anomalies.
Table (7) demonstrates that there is no significant relationship between systemic disease and dental anomalies.Note: The (**) means cannot be calculated.

Table 6: The relationship between low birth weight and dental anomalies
LowBirth weight (10)  Note: The (**) means cannot be calculated.Note: The (**) means cannot be calculated.

DISCUSSION
This study was designed to investigate the prevalence of dental anomalies among high school students aged 15 years old and study their relationship to the possible etiological factors.
The prevalence of hypodontia was 4.6% and this is lower than AL-Jourane (11) and Chung et al (12) .There was no statistically significant difference between hypodontia and the studied factors, in order to find an association between hypodontia and the studied factors a larger sample size should be taken or a follow up study about the patients that have the etiological factors to determine the presence of this anomaly.Talon cusp prevalence was 37.0% and this is higher than Danker et al (13) .This difference in the prevalence of talon cusp may be due to the fact that diagnosis of this dental anomaly in other study was based on radiographs solely without clinical examination and this might produce a false positive or negative diagnosis because talon cusps are easily discovered on radiograph as they present as V-shaped structure superimposed on the tooth but there is an exception to that which is a type 3 trace talon cusp that cannot be detected during radiographic examination (14) .
In this study the prevalence of supernumerary teeth was 0.8% and this is lower than Thilander et al (15) , it was difficult to study the relationship between supernumerary teeth and the studied factors due to the small number of this anomaly detected in the study and this may be attributed to the fact that most supernumerary teeth are impacted, asymptomatic and diagnosed incidentally during radiographic examinations, so panoramic radiograph is essential for detection of supernumerary teeth (16) .
In this study the prevalence of fusion was 0.7% and this is higher than Al-Ani (17) and this is may be due to larger sample size that had been taken in this study than other studies.
In this study the prevalence of gemination was 0.1% and this is equal to the results of Neville et al (18) .The etiology of double teeth may be attributed to trauma, hereditary and environmental factors, the cause may be attributed to the force of physical pressure that are generated during growth resulted in contact between adjacent teeth germs and union before calcification (19) .
In this study the prevalence of macrodontia and microdontia was 0.1% and 1.4% respectively, macrodontia and microdontia may be due to complex multifactorial interactions that include genetic and environmental factors occur during the long process of dental development (20) .
The prevalence of enamel defects was 30.5% and this finding was lower than (21) demarcated opacities which appear the most prevalent type of enamel defect 23.8% (males 20.5% and females 26.4%) followed by diffuse opacities 9.1% then by enamel hypoplasia 0.4%.
There was no statistically significant relationship between enamel defects and the studied factors but there was significant relationship between tooth extraction, enamel defects and demarcated opacities, this is may be due to trauma that result from tooth extraction and cause disturbance in the process of matrix degradation which occur during matrix formation stage to provide suitable condition for the commencement of maturation (22) .

( 1 )
Master Student.Department of pediodontic, College of Dentistry, University of Baghdad (2) Professor, Department of pediodontic, College of Dentistry, University of Baghdad.