INTRODUCTION: AIMS AND OBJECTIVE:

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1 Prevalence of Malocclusion among High School Students in Kathmandu Valley Dr. Basanta K. Shrestha,1 Dr. Rajiv Yadav,2 Prem Basel3 1. Associate Professor and Head, Department of Dentistry, IOM, TUTH 2. Assistant Professor, Department of Dentistry, IOM, TUTH 3. Epidemiologist Correspondence : drbkshrestha@gmail.com Abstract: Introduction: The malocclusion is a malrelationship between the arches in any of the planes or in which there are anomalies in tooth position beyond the normal limits. The epidemiological data has a key role in planning which varies between different countries, ethnic and age groups. Aims and objective: To find out the prevalence of malocclusion among high school students in three districts of Kathmandu valley. Materials and method: The sample consists of 937 children (537 males and 400 females) with the age groups between 14 and 16 years. The samples were selected voluntarily from seven different schools of Kathamandu valley using multistage sampling technique. This is a quantitative, cross-sectional descriptive study. Results: Normal occlusion is found to be in 27 %. The prevalence of Class I malocclusion is 59% followed by Class II (25%) and Class III (16%). Male to female ratio was found to be 57:43%. Out of two major ethnic groups, 64% of Indo Aryans and 36% of Janajati had malocclusion. Moreover, Class II malocclusion was seen more in Indo Aryans than in Janajati populations. Conclusion: The prevalence of normal occlusion was 27% and malocclusion was found to be 73%. Class I malocclusion is most prevalent followed by Class II malocclusion and the Class III malocclusion showed least prevalence. Keywords: High school students, Malocclusion, Prevalence INTRODUCTION: The malocclusion is a malrelationship between the arches in any of the planes or in which there are anomalies in tooth position beyond the normal limits.1 According to Klages and Zenter, a person with malocclusion may refrain oneself from social contacts, may lose career opportunities and might feel shame about their dental appearance.2 The malocclusion has been shown to affect oral health, increased prevalence of dental caries and can cause tempero - mandibular joint disorders.1 Although some people seek orthodontic treatment to improve their oral functional ability, most of the patients seek orthodontic treatment because of their desire to look attractive and improve their self-esteem.3,4,5 The benefits of getting orthodontic treatment include prevention of tissue damage, improvement of esthetics as well as the physical function.6 The epidemiological data has a key role in planning appropriate levels of orthodontic services. The occurrence of occlusal anomalies varies between different countries, ethnic and age groups.7, 8, 9, 10, 11, 12 The incidence of malocclusion has been reported to vary from 11% up to 93% in different parts of the world.8, 9, 10, 11, 12 Even in our neighboring country India, different studies have shown variation in the prevalence of malocclusion from 20% - 43%.13, 14,15 Although a study16 was done on malocclusion among patients seeking orthodontic treatment in one of the hospitals in eastern Nepal, but that study was only limited to the patients coming to orthodontic department. Similarly another study on prevalence of malocclusion among medical syudents in Institute of Medicine, Nepal was done recently by Shrestha and Yadav, but this study was a pilot study and limited sample were taken,25 hence a further study to evaluate the prevalence of malocclusion is not done so far in Nepal. Therefore, this study was proposed. AIMS AND OBJECTIVE: General Objective: 1. To find the prevalence and various grades of malocclusion among years adolescents in high school students of all three districts of Kathmandu Valley. Specific objectives: 1. To find the prevalence of normal occlusion ORIGINAL ARTICLEPage 2

2 2. To identify the proportion of class I, Class II and Class III malocclusion 3. To compare the prevalence of malocclusion between male and females 4. To establish a baseline data for study of prevalence of malocclusion among Nepalese population MATERIALS & METHOD: Study Design: Cross-sectional descriptive study. Study population: The study population included year-old adolescents studying in high school of all three districts of Kathmandu Valley. Exclusion criteria: Subjects with craniofacial anomalies (clefts and syndromes) and non-nepali nationals were excluded from the study. Sample size and sampling methods: 1. Sample size calculation: The sample size (n) was calculated by using the formula: z2pq/l2 Where, z = Value of z in 95% Confidence level=1.96, p= Prevalence rate = 30% = 0.3, q = (1- p) = (1-0.3) = 0.7, l = allowable error (10% of p) = 10/100 x 0.3= 0.03 n = x 0.3 x 0.7 / (0.03)2 = Sampling process: Multistage sampling process was adapted to include the adolescents in the study group. (a) First stage: Review of total list of the schools and selection of the schools for the study Inclusion criteria: High Schools with students more than 100 in the specified age groups (b) Second stage: Division of Boys and Girls High Schools. (c) Third stage: Selection of the equal no of boys and girls schools using random sampling method. (d) Fourth stage: Visiting the school and to conduct orthodontic screening to all students till the sample size is met. Study period The study was conducted over a period of 6 months. Data collection method and tools: A survey format was developed to record the general background and findings of dental screening regarding status of occlusion that includes orthodontic variables17 as well as Index of Orthodontic Treatment Need (IOTN).18 Clinical examination- The students were examined at the schools, in a quiet classroom without external interference, under natural or artificial illumination. The examination lasted approximately 15 minutes per child, following the World Health Organization (1985) guidelines. 17 The assessment of dental occlusion was carried out using latex gloves, dental mouth mirrors, and mill metric rulers. No radiographs, study casts, or previous written records were used. Personal data and information about orthodontic treatment were obtained directly from the students. Orthodontic variables: The following orthodontic variables were studied - Molar relationship. The relationship between the upper and lower first permanent molars was determined according to Angle s classification: class I, the mesiobuccal cusp of the upper first molar occludes in the buccal groove of the lower first molar; class II, the first lower molar is distally positioned relative to the upper first molar; and class III, the lower first molar is mesially positioned relative to the upper first molar. Patients with subdivision malocclusions were included in the Class II or Class III groups on the basis of the predominant occlusal characteristic, or according to the relationship between the canines. Overjet. Overjet (OJ), the distance between the edge of the upper central incisor and the labial surface of the lower central incisor, was measured in millimeters using a metal ruler. The overjet from 0 mm to 3.5 mm was accepted as normal. The increased OJ from the point of clinical relevance was divided into three groups: from 3.5 to 6 mm, from 6 to 9 mm, and more than 9 mm, respectively. Overbite. Overbite (OB), the perpendicular distance from the edge of the lower central incisor to the upper central incisor edge, was measured in millimeters and considered as open bite (< 0 mm), normal overbite (0 to 4.0 mm), and deep bite (> 4.0 mm). Posterior crossbite. A posterior crossbite was diagnosed when there was a crossover of at least one tooth in the posterior segments of the dental arches. A posterior crossbite could be unilateral (right or left) or bilateral. Scissor bite. A scissor bite was considered to be present when the palatal cusps of the upper molars were positioned buccally in relation to the buccal cusps of the lower molars. Crowding and Spacing. The crowding was assessed by totaling the sum of slipped contacts measured in all the segments. The lack of space not exceeding 2 mm was considered as no crowding, mm mild crowding, mm moderate crowding, more than 7.1 mm

3 severe crowding. Surplus space in the dental arch exceeding 2 mm was considered as spacing. Diastema. A midline diastema was considered to be present when there was a space of at least 2 mm between the maxillary central incisors. Quality assurance Training and calibration of examiner: Oral examination was performed by two trained and calibrated examiners. Before the survey, 60 students were examined by each of the two investigators to assess inter-examiner reliability and Kappa values for both the examiners was found to be 0.87 and 0.88 respectively. The students were examined by using dental probe and plane mouth mirror. Sufficient number of autoclaved instruments were made available to avoid the interruption during the study. After each day of examination, the entire instruments were autoclaved. Ethical consideration: Before start of the study, an ethical clearance was obtained from the Ethical Review Board of IOM. Each study individual was informed about the objective and benefit of the study. The informed consent form was developed to ensure consent of each study individual. Statistical Analysis: Firstly, data were coded and entered into Excel sheet. To maintain the data quality (validity) rechecking and cross checking were done during data entry phase. After the entry of the data to excel sheet necessary data cleaning were done. Secondly, data were transformed into SPSS 16.0 version where further cleaning, coding, recoding, cross checking, processing and analysis were done. Primarily, univariate and bivariate analysis were done to measure the prevalence of malocclusion and various other occlusal traits. (Note: we did not do any significant testing per se) RESULTS: Out of 937 subjects only 26.7 % had normal occlusion and 73.3% had malocclusion. Among 73% of malocclusion Class I malocclusion contributed to 59% while Class II and Class III malocclusion contributed to 25% and 16% respectively. Among 25% of Class II Malocclusion, Class II div 2 were 85%, Class II div 1 were 13%, while Class II div 1 subdivision were only 2% Out of 16% Prevalence of Class III malocclusion, Bilateral Class III were 51.9%, Class III subdivision 1 consists of 45.5 % while Class III subdivision consists of only 2.8% Class III subdivision 1 -one side III, other side I, Class III subdivision 2- one side III, other side II Among 937 study units, the ratio of male to female was 57: 43, indicating that males had slightly higher prevalence of malocclusion than females. Fig. 1: ORIGINAL ARTICLE Page 3 Page 4 Fig. 2: Fig. 3: Fig. 4: Vol. 2 No. 1, 2012 Fig. 5:

4 The pattern of malocclusion among male and female are well compared in following chart Nepelese population have mixed ethnic back ground but these are broadly categorized into Indo Aryan and Janjati ethnic group. In our study Indo Aryans consisted of 64% while Janjati only 36% Following chart gives the pattern of malocclusions among these ethnic groups DISCUSSION: The prevalence of malocclusion has been found to vary with the different population, race and origin. The result of our study showed that 73% had malocclusion. The prevalence of malocclusion in our study is almost similar to the study done by Basanta. K. Shrestha and Rajiv Yadav in medical students of IOM (90.4%)25 but higher than the study done by Usha Mohan Das et al in school children of Banglore (71%)19 and Nagaraja Rao (28.8%) in school children of Udupi, Karnataka.24 According to our study, Angle s Class I malocclusion was present in 59%, Class II in 25%, and Class III in 16% of the sample size which is similar to the previous study done by Basanta K. Shrestha and Rajiv Yadav among medical students in IOM.25 Hyng-Seon Yu et al (S.Korea) studied on the trends of malocclusion in patients coming to the orthodontic department and found 33.3% Class I malocclusion, 28.6% Class II malocclusion and 38.15% Class III.22 The prevalence of Class III is markedly different from our study (Fig. 3) which may be because of racial predisposition to certain malocclusion. Among the students participated in our study from three districts male to female ratio was 57:43. The prevalence of normal occlusion was found to be more in female than in a male population where as prevalence of class I, Class II, Class III malocclusion were more in male as compared to female. In our study we have given due attention to the ethnic groups and accordingly we have categorized into two major ethnic group as Indo Aryans and Janajati with the ratio being 64% and 36% respectively. Both ethnic groups had almost equal ratio of normal occlusion and malocclusion except for the Class II malocclusion which was seen more in Indo Aryan Group. CONCLUSION: The prevalence of normal occlusion was 27% and malocclusion was 73% in all three district of Kathmandu valley. Class I malocclusion was most prevalent followed by Class II malocclusion and the Class III malocclusion showed least prevalence. Prevalence of normal occlusion was seen more in females; whereas prevalence of malocclusions was seen more in males. Prevalence of normal occlusion, Class I and Class III malocclusion were seen to be almost equal in both Indo Aryan and Janajati ethnic groups, whereas Class II malocclusion was more prevalent in Indo Aryan population. Fig. 6: Fig. 7: Fig. 8: Fig. 9:

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