MALAYSIAN DENTAL JOURNAL. Orthodontic Treatment Need Among Dental Students Of Universiti Malaya And National Taiwan University

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1 MALAYSIAN DENTAL JOURNAL Malaysian Dental Journal (2009) 30(1) The Malaysian Dental Association Orthodontic Treatment Need Among Dental Students Of Universiti Malaya And National Taiwan University Chee Swee Meai. Faculty of Dentistry, Universiti Malaya Saw Woon Ling. Faculty of Dentistry, Universiti Malaya Wey Mang Chek. BDS (Malaya), FDSRCS (England), MOrthRCSEd, MOrth (Hong Kong), Senior Lecturer in Orthodontics, Faculty of Dentistry, Universiti Malaya ABSTRACT The aim of this study was to assess the orthodontic treatment need of dental students in Universiti Malaya, and to assess and compare the orthodontic treatment need of Chinese dental students in Universiti Malaya and National Taiwan University, using the Index of Orthodontic Treatment Need (IOTN). This is a cross-sectional study. 50 Universiti Malaya dental students, the racial ratio of which was based upon the Malaysian major racial composition, (n = 34 Malay, n = 12 Chinese, n = 4 Indian), were randomly selected, whilst 30 National Taiwan University dental students were selected on voluntary basis. Consent and data on personal, orthodontic treatment and medical histories were taken. Digital photographs, bite registration and impressions of the Universiti Malaya sample were taken for assessment of dental health (DHC) and aesthetic (AC) components. Only photographs of the National Taiwan University samples were taken for assessment of AC. IOTN calibration exercise was done. Ten randomly selected data were repeated at least 2 weeks apart. Inter- and intra-examiner errors, treatment need of Universiti Malaya sample and comparison between treatment need of Universiti Malaya and National Taiwan University Chinese dental students were analyzed using SPSS version % of the Universiti Malaya sample did not need orthodontic treatment (DHC grades 1 and 2), 34% had borderline need (grade 3) and 16% had definite need (grades 4 and 5). For the aesthetic component, 96% did not need treatment (AC grades 1, 2, 3 and 4) and 4% had borderline need (grades 5, 6 and 7). There was no significant difference between the AC assessment of Universiti Malaya and National Taiwan University Chinese (p > 0.05). As conclusion, majority of Universiti Malaya students did not require orthodontic treatment. Chinese dental students in Universiti Malaya and National Taiwan University had similar level of treatment need according to IOTN Aesthetic Component. Key Words Orthodontic treatment need, dental students, dental health component, aesthetic component. Introduction In Malaysia, orthodontic treatment is yet widely provided to the public due to the limited services and facilities available. Therefore, estimation of orthodontic treatment need is essential when the orthodontic resources are limited and when the availability of treatment is unevenly spread. However, data on malocclusion and orthodontic treatment need in Malaysia are still limited. Studies on the dentition of three major ethnic groups (Malays, Chinese and Indians) in Malaysia have been done by Woon KC in and Woon KC, Thong YL and Rahimah AK in Later studies on malocclusion and orthodontic treatment need in schoolchildren (age ranging from years old) were carried out by Abdullah MSB and Rock WP in and Rashidah E, Ishak AR and Allister JH in More studies are needed to investigate malocclusion and orthodontic treatment need with relevance to sex, different age range and in comparison with other ethnic groups. Orthodontic treatment need indices to identify patients with greater need are indeed essential. Some of the indices used in assessing malocclusion are Occlusal Index 5, Handicapping Malocclusion Assessment Record 6, Index of Orthodontic Treatment Need (IOTN) 7, Index of Complexicity, Outcome and Need (ICON) 8, etc. However, because of the varying impact 6

2 Chee SM / Saw WL / Wey MC of similar malocclusion under dissimilar cultural and social milieus, no index has yet been universally accepted as the most ideal one for assessing treatment need at present. Having said that, the IOTN is widely used in UK and the World Health Organization (WHO) used IOTN as the index for collecting epidemiological data on orthodontic treatment need. IOTN consists of aesthetic component (AC) and dental health component (DHC) to record the perceived aesthetic impairment and dental health in term of function respectively. It is meant to identify those individuals who would be most likely to benefit from orthodontic treatment. IOTN is simple to use, valid and reliable. Orthodontic treatment need in young adults should also be investigated as the patients in this age range are very concerned about their dentofacial aesthetics. They comprise a large group of patients requesting orthodontic treatment. With changes brought about by growth, the orthodontic treatment need in young adults may not be the same as those in schoolchildren (age range from years old) of similar population. Studies have shown that the need for the orthodontic treatment in adults is high 9, 10. Assessment of orthodontic treatment need helps to identify individuals who will benefit from the treatment while reducing the burden of long waiting lists in public dental health care centre. Hence the need for more studies to investigate the orthodontic treatment need among young adults of this region. A number of studies have been done on the prevalence of malocclusion in different populations and ethnic groups. Not many studies compared the Chinese ethnic groups from different regions. A standardized common criteria of malocclusion for an objective and reliable comparison have not been established, rendering the comparison of findings of different individual studies difficult. Both the Chinese population in Taiwan and Malaysia originated from China a century ago. They are considered to have established their own malocclusion characteristic. It is of interest to compare the orthodontic treatment need of Chinese in Malaysia and Taiwan, as there has yet to be studies done to compare the treatment need between both populations. The purpose of this study is to assess the orthodontic treatment need of dental students (age ranging from years old) in Universiti Malaya, and to assess and compare the orthodontic treatment need of Chinese dental students in Universiti Malaya and National Taiwan University, using the Index of Orthodontic Treatment Need (IOTN). MATERIALS AND METHODS and 1% Others. The ethnic distribution of the sample was, Malay n = 34, Chinese n = 12 and Indian n = dental students from National Taiwan University (NTU) were selected on voluntary basis. Students who were undergoing or had undergone orthodontic treatment or serial extraction before, and those with syndromes affecting craniofacial region e.g. cleft palate, were excluded. Ethical approval was obtained. Informed consent was acquired from all participants, who were also required to fill in a simple questionnaire related to age, gender, the race of parents and grandparents, previous exposure to orthodontic treatment and medical history related to syndromes suffered. The informed consent and questionnaire were checked for completeness and collected by one investigator at the same session as impression and intraoral color photograph taking. In the UM sample, digital photographs, bite registration and upper and lower impressions were taken for study model fabrication. The study models were used for Index of Orthodontic Treatment Need (IOTN) assessment of dental health component (DHC). Color photographs were taken of intra-oral labial view using cheek retractors and with upper and lower arches in centric occlusion for aesthetic component (AC) assessment of IOTN (Figure 1). Bite registration with registration paste were taken in centric occlusion. Impression trays were first selected according to size and adhesive applied, for impressions to be taken with alginate. Study casts were poured from stone less than one hour after alginate impression. Measurements were done with metal ruler on study casts for assessment of DHC. Study model analysis was performed in accordance to the IOTN protocol (Table 1). In the NTU sample, only intra-oral color photographs were taken for assessment of IOTN AC alone. Calibration exercise was done for IOTN assessment. Intra-examiner reproducibility was assessed by repeating measurements from randomly selected 20% of the sample 2 weeks apart and the results analyzed using Kappa test of SPSS version 12. Interexaminer validity was similarly assessed using Kappa test of SPSS version The orthodontic treatment need of young Malaysian adults was assessed descriptively. The treatment need between Chinese dental students of UM was compared to that of NTU using Fisher s exact test of SPSS version 12.0, after re-categorization of AC grades 1, 2, 3 and 4 to the category of no treatment need and grades 5, 6 and 7 to the category of borderline treatment need 11. This is a cross-sectional study. 50 dental students, both male and female, from year 3 to 5 studying in Universiti Malaya (UM) with the age ranging from 20 to 25 years, were randomly selected according to racial composition of 67% Malay, 25% Chinese, 7% Indian 7

3 Orthodontic Treatment Need Among Dental Students Of Universiti Malaya And National Taiwan University Table 1 - The Dental Health Component (DHC) of Index of Orthodontic Treatment Need (IOTN) Grade1 No treatment required 1. Extremely minor malocclusions, including displacements less than 1 mm Grade 2 Little 2.a Increased Overjet > 3.5 mm but 6 mm (with competent lips) 2.b Reverse overjet greater than 0 mm but 1mm 2.c Anterior or posterior crossbite with 1mm discrepancy between retruded contact position and intercuspal position 2.d Displacement of teeth > 1mm but 2mm 2.e Anterior or posterior open bite > 1mm but 2mm 2.f Increased overbite 3.5mm (without gingival contact) 2.g Prenormal or postnormal occlusions with no other anomalies. Includes up to half a unit discrepancy Grade 3 Borderline need 3.a Increased overjet > 3.5 mm but 6 mm (incompetent lips) 3.b Reverse overjet greater than 1 mm but 3.5mm 3.c Anterior or posterior crossbites with >1mm but 2mm discrepancy between the retruded contact position and intercuspal position 3.d Displacement of teeth > 2mm but 4mm 3.e Lateral or anterior open bite > 2mm but 4mm 3.f Increased and incomplete overbite without gingival or palatal trauma Grade 4 Treatment required 4.a Increased overjet > 6mm but 9 mm 4.b Reverse overjet > 3.5 mm with no masticatory or speech difficulties 4.c Anterior or posterior crossbites with > 2 mm discrepancy between the retruded contact position and intercuspal position 4.d Severe displacements of teeth > 4 mm 4.e Extreme lateral or anterior open bites > 4 mm 4.f Increased and complete overbite with gingival or palatal trauma 4.h Less extensive hypodontia requiring prerestorative orthodontics or orthodontic space closure to obviate the need for a prosthesis 4.l Posterior lingual crossbite with no functional occlusal contact in one or more buccal segments 4.m Reverse overjet > 1 mm but < 3.5 mm with recorded masticatory and speech difficulties 4.t Partially erupted teeth, tipped and impacted against adjacent teeth 4.x Existing supernumerary teeth Grade 5 Treatment required 5.a Increased overjet > 9 mm 5.h Extensive hypodontia with restorative implications (more than one tooth missing in any quadrant requiring pre-restorative orthodontics) 5.i Impeded eruption of teeth (apart from 3rd molars) due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause 5.m Reverse overjet > 3.5 mm with reported masticatory and speech difficulties 5.p Defects of cleft lip and palate 5.s Submerged deciduous teeth 8

4 Chee SM / Saw WL / Wey MC Figure 1 - The Aesthetic Component of Index of Orthodontic Treatment Need (IOTN) Figure 2 Overall Distribution of Dental Health Component (DHC) Scores among Dental Students in Universiti Malaya, (n = 50) Aesthetic Component (AC) RESULTS The weighted Kappa agreement scores for dental health component (DHC) of Universiti Malaya (UM) sample for one examiner and aesthetic component (AC) of National Taiwan University (NTU) sample for one examiner was 0.71 and 0.63 respectively, which indicated good intraexaminer reproducibility 12 (Table 2). The weighted Kappa agreement scores for DHC and AC of UM sample between two examiners were 0.62 and 0.63 respectively, which indicated good inter-examiner validity. Figure 3 shows the distribution of AC scores in UM sample. 96% did not need treatment (AC grades 1, 2, 3 and 4) and 4% had borderline need (grades 5, 6 and 7). None of the subjects had definite need for treatment (grades 8, 9 and 10) to improve dental aesthetic. Figure 3 - Overall Distribution of Aesthetic Component (AC) Scores among Dental Students in Universiti Malaya, (n = 50) Table 2 - Guidelines for the Interpretation of Kappa Kappa statistic Strength of agreement < 0.00 Poor Slight Fair Moderate Substantial Almost perfect Dental Health Component (DHC) Figure 2 shows the distribution of DHC scores in UM sample. 50% of the sample had no need for orthodontic treatment (DHC grades 1 and 2), 34% had borderline need (grade 3) and 16% had definite need (grades 4 and 5). 9

5 Orthodontic Treatment Need Among Dental Students Of Universiti Malaya And National Taiwan University Treatment need among ethnic group in UM Sample Table 3 shows the distribution of DHC scores (%) among ethnic group. The Malay and Chinese had similar definite need for treatment but none of the Indian sample had definite need for treatment. Table 3 - Distribution of Dental Health Component (DHC) Scores among Ethnic Groups of Universiti Malaya Dental Students Ethnic Sample No Need, Borderline Definite Group size, (n) % Need, % Need, % Malay Chinese Indian Table 4 shows the distribution of AC scores (%) among ethnic group. A small minority of Malay sample (5.9%) had borderline need for treatment, whereas both Chinese and Indian did not need orthodontic treatment. Table 4 - Distribution of Aesthetic Component (%) Scores among Ethnic Groups Ethnic Sample No Need, Borderline Definite Group size, (n) % Need, % Need, % Malay Chinese Indian On the whole there is a general higher treatment need based on assessment using dental health component as compared to aesthetic component assessment. AC assessment among UM and NTU Chinese Table 5 shows the distribution of AC scores (%) among Chinese dental students in UM and NTU. 100% of UM Chinese and 96.7% of NTU Chinese fell into AC grades 1 to 4, with no need for orthodontic treatment, the remaining of 3.3% of NTU Chinese fell into grade 6, with borderline need for treatment. The proportions of treatment need categories between Chinese in NTU and UM were not significantly different (P = 0.999) (Table 5). Therefore, there is no significant association between Chinese students in different universities and AC. Table 5 - Comparison of Orthodontic Treatment Need According to Aesthetic Component of Index of Orthodontic Treatment Need Between Chinese Dental Students of Universiti Malaya (UM) and National Taiwan University (NTU) University Sample size, (n) No treatment need, (%) Borderline need, (%) UM (100) 0 NTU (96.67) 1 (3.33) a. Fisher s Exact Test. DISCUSSION P value a The results of this study showed that half of the Universiti Malaya (UM) sample did not require orthodontic treatment according to dental health component (DHC). This is in contrast to the study reported by Abdullah (2001) 3 where a smaller proportion did not need treatment and a bigger proportion had need for treatment. The differences in results between both studies are likely to be multifactorial. There is a difference in the sample size whereby the study by Abdullah involving a bigger sample size. The sample used in this study excluded those dental students who had previously received or ongoing orthodontic treatment, thereby underestimating the orthodontic treatment need in present samples. The present study involved dental students aged 20 to 25 years old as compared to the other study, which involved schoolchildren aged 12 to 13 years old. This variation in sample age group may have caused the variation in the findings between both studies. The Malay and Chinese ethnic groups had comparable proportions of definite treatment need based on DHC grades 4 and 5 which is similar to result reported by Abdullah (2001) 3. A higher proportion of subjects had definite treatment need based on dental health (DHC) rather than on dental aesthetic (AC) reasons with all ethnic groups and this has been shown in another study by Mandall et al. (1999) 13. AC scale is based on ten color photographs showing frontal intra-oral view of different levels of dental attractiveness. Crossbite, spacing, crowding and impacted teeth that occur in buccal segments have no influence in determining AC grading; hence usage of assessment with AC alone is more likely to result in underestimation of orthodontic treatment need. All of the Chinese dental students in UM and almost all in National Taiwan University (NTU) had no need for orthodontic treatment according to AC (grades 1 to 4). Only a minority of Chinese dental students in NTU had moderate need for treatment (AC grades 5 to 7). The findings showed that most of the dental students from both dental schools have good dental attractiveness, therefore less need for orthodontic treatment based on AC. Assessment of treatment need between both samples would have been better supported if both AC and DHC had been used 3. However, DHC was not incorporated into the 10

6 Chee SM / Saw WL / Wey MC assessment of the NTU sample due to financial and ethical issue constraints, which justifies further investigations in future studies. To date, no study has been done to compare orthodontic treatment need between both populations. This study showed that there is no significant difference in orthodontic treatment need between Chinese in UM and NTU (P > 0.05). Although no previous direct comparison has been recorded, the mean DAI score of Chinese in Taiwan had been reported to be 25.9 by Katoh et al. (1998) 14 and in Malaysia had been reported to be 24.6 by Rashidah et al. (2001) 4. Both IOTN and DAI indices showed that the level of orthodontic treatment need between both populations were identical. This finding may suggests that a common genetic source had a stronger influence on the orthodontic treatment need in these two populations of Chinese origin rather than environmental factors. The findings of this study are limited by several factors such as financial, time and ethical problems during data collection in Taiwan. Only photographs of the NTU samples had been taken for assessment of AC. In addition, due to time constraint, only 30 NTU sample on voluntary basis were targeted. As for the UM sample, majority of UM dental students had been orthodontically treated before, probably due to increased dental awareness, thus reducing UM sample pool. Furthermore, to eliminate the influence of racial difference on the assessed treatment need and to reflect a treatment need based on the existing true racial composition of the Malaysian population, the UM sample was selected according to the Malaysian racial composition of 67% Malay, 25% Chinese, 7% Indian and 1% Others (Malay n=34, Chinese n=12 and Indian n=4). This has further reduced the sample size of the different ethnic groups drastically, especially for the Indian sample, thus reducing the power of observations carried out. Generalization of the findings of this study to the Malaysian population should be done with caution. Due to similar reasons, comparisons between ethnic groups could not be carried out statistically. For the assessment of DHC, subjects with DHC grades 4h or 5h had been assumed to have missing teeth without confirmation from radiographs, as that had not been within the ethical scope of this study. However, there was a possibility that some of them might have impacted permanent successors, and therefore meant to be in the DHC 5i category instead. Nevertheless, subjects with 4h, 5h, and 5i categories would still fall into the same category of high treatment need. Currently there is increasing social pressure for the provision of orthodontic treatment in the government dental service which is evident in the 3 to 5 years of waiting list. The present number of orthodontists in this country is insufficient to meet the apparent demand4. Should the findings from this study reflect the true lack of treatment need as found in the majority of the subjects, it is then possible that many of these patients may not require orthodontic treatment after all. Although the results of this pilot study involving 50 samples could not be directly applied to the community at large, it did provide sufficient information to justify the need for future studies on orthodontic treatment need in adults to be conducted on a larger scale within the Malaysian population. The existence of subjects who had definite need for orthodontic treatment based on dental health issues despite the readily available orthodontic care within the community from which the sample was derived warrants further assessment and evaluation of the provision and utilization of orthodontic care in the community. CONCLUSION Based on Index of Orthodontic Treatment Need (IOTN) assessment of Dental Health Component (DHC), half of the Universiti Malaya (UM) sample did not need orthodontic treatment, a third had borderline need and less than a fifth had definite need. Majority (96%) had absolutely no treatment need and very few (4%) had borderline need according to IOTN assessment of Aesthetic Component (AC). There was no difference found between the AC assessment of Chinese dental students in UM and National Taiwan University (NTU), i.e. all (UM) or majority (NTU) of the students in both universities had no orthodontic treatment need. In addition, it was found that the DHC consistently recorded higher proportions with treatment need as compared to AC. In order to obtain better information on treatment need, it appears that both components of IOTN need to be applied. ACKNOWLEDGEMENT This survey is funded by PJP vote. REFERENCES 1. Woon KC. Primary dentition occlusion in Chinese, Indian and Malay groups in Malaysia. Aust Orthod J 1988;10(3): Woon KC, Thong YL, Rahimah AK. Permanent dentition occlusion in Chinese, Indian and Malay group in Malaysia. Aust Orthod J 1989;11(1): Abdullah MSB, Rock WP. Assessment of orthodontic treatment need in 5,112 Malaysian children using IOTN and DAI indices. Community Dent Health 2001;18: Rashidah E, Ishak AR and Allister JH. Epidemiology of malocclusion and orthodontic treatment need of yearold Malaysian schoolchildren. Community Dent Health 2001;18: Summers C. The occlusal index. A system for identifying and scoring occlusal disorders. Am J Orthod Dentofacial Orthop 1971;59: Salzmann JA. Handicapping malocclusion assessment to establish treatment priority. Am J Orthod 1968;54: Brook PH, Shaw WC. The development of an index of orthodontic treatment priority. Eur J Orthod 1989;11: Daniels C, Richmond S. The development of The Index 11

7 Orthodontic Treatment Need Among Dental Students Of Universiti Malaya And National Taiwan University of Complexicity, Outcome and Need (ICON). Journal of Orthodontics 2000;27: Salonen L, Mohlin B, Gotzlinger B, Hellden L. Need and demand for orthodontic treatment in an adult Swedish population. Eur J Orthod 1992;14: Soh J and Sandham A. Orthodontic treatment need in Asian adult males. Angle Orthod 2004;74: Richmond S, Shaw WC, Stephens CD, Webb WG, Roberts CT, Andrews M. Orthodontics in the general dental services of England and Wales: a critical assessment of standards. Br Dent J 1993;174: Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977;33: Mandall NA, McCord JF, Blinkhorn AS, Worthington HV, O'Brien KD. Perceived aesthetic impact of malocclusion and oral self-perception in years old Asian and Caucasian children in Greater Manchester. Eur J Orthod 1999;21: Katoh Y, Ansai T, Takehara T, et al. A comparison of DAI scores and characteristic of occlusal traits in three ethnic groups of Asian origin. Int Dent J 1998;48: Address for correspondence: Dr. Wey Mang Chek Department of Children s Dentistry and Orthodontics, Faculty of Dentistry, Universiti Malaya, Kuala Lumpur. Tel: , Fax: address: weymc@um.edu.my 12

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