British Journal of Orthodontics

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The Prevalence of Orthodontic Treatment Need Ann Holmes To cite this article: Ann Holmes (1992) The Prevalence of Orthodontic Treatment Need, British Journal of Orthodontics, 19:3, 177-182, DOI: 10.1179/bjo.19.3.177 To link to this article:

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British Journal of Orthodontics/Vol. /9{1992/177-182

The Prevalence of Orthodontic Treatment Need ANN HOLMES M.MED.~CI., B.D.S., F.D.S., M.ORTH. Orthodontic Department, The Charles Clifford Dental Hospital, Wellesley Road, Sheffield SIO 2SZ Received for publication June 1991

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Abstract. The prevalence of unmet orthodontic treatment need amongst 955 12-year-old Sheffield children has been assessed using the Index of Orthodontic Treatment Need [ I.O. T.N.]. The Index was found to be quick and simple to use, and demonstrated very good levels of intra-examiner agreement. Index words: Index of Orthodontic Treatment Need [I.O.T.N.], Prevalence of Orthodontic Treatment Need, 12-year-olds.


Many dental surveys in the United Kingdom have reported on the prevalence of malocclusion and orthodontic treatment need. Gardiner (1956), in a subjective assessment of I000 Sheffield school children, aged 5-15 years, considered 50·4 per cent to be in need of orthodontic treatment; while Haynes, examining 11-12-yearolds, found only 26·85 per cent to have 'normal' occlusions (Haynes, 1970). In 1983 the United Kingdom Children's Dental Health Survey (Todd and Dodd, 1985) reported that 40·0 per cent of 12year-olds had some treatment need. Lack of reliable and valid indices, and the absence of any standardization of reporting have, in the past, prevented any meaningful comparisons between various surveys. There are, therefore, inevitable wide variations in the percentage of subjects assessed as requiring orthodontic treatment. There now exists the opportunity, using the Index of Orthodontic Treatment Need (I.O.T.N.; Brook and Shaw, 1989), to assess treatment need and ultimately to compare populations. The present investigation was designed to record the level of treatment need amongst a randomly selected sample of Sheffield schools containing 12-year-old children using the I.O.T.N. Methods

The Index is comprised of two components: a Dental Health Component (DHC; Brook and Shaw, 1989), used to record the functional and dental health indications for treatment; and an 030 1-228X/92/008000 +00$02.00

aesthetic component (Evans and Shaw, 1987; Brook and Shaw, 1989), used to record the aesthetic impairment of the malocclusion to the individual. The I.O.T.N. aims to provide an objective assessment of the patient's need for orthodontic treatment. Calibration in the use of the I.O.T.N. was carried out using study models. Study population

Since the total number of 12-year-old children in Sheffield was approximately 4800, attending 89 schools, a sample was taken from those eligible. All children attending Local Educational Authority maintained middle and secondary schools, excluding special and private schools, in Sheffield during the period I st October 1988-31st July 1989, and who had attained their twelfth, but not their thirteenth birthday on the day of the survey examinations at their school were eligible for inclusion in the study population. For the purposes of the orthodontic survey Sheffield was divided into five geographic areas, which corresponded to five varying demographic areas of the city: North West, South West, North East, South East and Central. In each area the schools were listed in ascending order of the number of 12-year-olds in each. A cluster sample of 25 per cent of schools from each area was selected, using random number tables, giving a total of 22 schools in all. All 12-year-olds present on the day of screening in these schools were examined. In the event of less than 85 per cent of the children from the school being available for examination a return visit was made to the school. V 1992 British Society for the Study of Orthodontics

BJO Vol. /9 No. J

178 A. Holmes

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The Examination

Consent forms were circulated to all parents of the children involved in the survey prior to the visit. The examination was carried out in the school medical room, examination conditions being as standardized as possible for each school. Only one clinical examiner, an orthodontist, was used throughout this survey. The dental health and aesthetic components of the I.O.T.N., together with the trait defining the functional and dental health indications for treatment, were then recorded by the orthodontist. The child was also required to separately rate their own level of dental attractiveness, using the aesthetic component of the I.O.T.N. The date of birth, sex, race, and geographic sector of the city to which the school belonged were also recorded. The clinical examination time was approximately 30 seconds to l minute. Radiographs were not available or taken during the survey. Children who were receiving orthodontic treatment at the time of the examination were excluded from the survey. Since the aim of the study was to establish the level of unmet treatment need it was felt, given the small number of children undergoing treatment, that the degree of bias would be minimal. Tests of reproducibility

One school was chosen at random for re-examination to establish intra-examiner reproducibility. Children were re-examined using the same criteria as in the initial examination. The re-examination was carried out 6 weeks following the first examination.


years, were examined. Forty-one (4·12 per cent) of the children examined were undergoing orthodontic treatment at the time of the examination and were also excluded from the study, leaving 955 children in the sample. The mean age and sex distribution of the sample are shown in Table I. Ethnic origin

Of children in the sample, 915 (95·8 per cent) were European in origin, 12 (1·3 per cent) Afro-Caribbean, 19 (2 per cent) Asian, four (0·4 per cent) Oriental, and five (0·5 per cent) were of mixed race. Dental Health Component [DHC]

The distribution of DHC grades amongst the sample population is shown in Fig. I. Grade I represents no dental health requirement for treat-

Results Twenty-two schools, containing 1107 12-year-old children, were randomly selected for examination. One:-.hundred-and-eleven of these children were absent at the time of the examination and were excluded from the study. In total996 children, 90·0 per cent of the sample, in the age range 12·00-12·99 TABLE I

Age and sex distribution of the sample



Male Female

503 452



SE percentage= 1·61.

Mean age in years


52·67 47·32

12·54 12·55

0·27 0·28





TABLE 2 Distribution of the scoring occlusal trait ( n = 955) amongst the Dental Health Component grades DHC Scoring trait






Cleft lip/palate Increased overjet Reversed overjet Cross-bites Crowding Impeded eruption Open bite Increased overbite Hypodontia Normal occlusion

0 0 0 0 0 0 0 0 0 57

0 56 8 13 184 0 I 13 0 0

0 89 10 30 146 0 5 37 0 0

0 63 2 27 85 0 2 4 18 0

3 21 0 0 0 81 0 0 0 0

3 229 20 70 415 81 8 54 18 57








Orthodontic Treatment Needs

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FIG. 2


A Kappa value of 0·84, for the DHC, representing almost perfect intra-examiner agreement, was obtained. Perfect agreement was achieved in 44 (88 per cent), cases, while in six (12 per cent) cases there was a difference of one grade between the first and second examination. No cases were found in which the difference between examinations was greater than one DHC grade. All six cases of discordance occurred in grades 2 or 3. Two children were placed in the lower treatment need group, grade 2, on reexamination and four in the higher treatment need group, grade 3. A Kappa value of0·88 was obtained for Aesthetic Component of the I.O.T.N., again representing almost perfect intra-examiner agreement. Perfect agreement was achieved in 45 (90 per cent) cases, while the remaining five (10 per cent) cases were under-rated by one point on the scale, when compared with the first examination, while none were over-rated. Demographic areas

The current survey failed to indicate a significant difference in either dental health or aesthetic treatment need, between Sheffield's five demographic areas. Discussion FIG. 3

ment while grade 5 represents very great treatment need. The most severe trait identified, which is the basis on which the individual is graded for the DHC, is shown in Table 2. Aesthetic Component

The distribution of the Aesthetic Component scores, by the orthodontist and the child, which are used to assess the aesthetic impairment of the malocclusion are shown in Figs 2 and 3. A score of I represents the most attractive dentition while 10 represents the least attractive. Intra-examiner agreement

Fifty children were re-examined to test the level of intra-examiner reproducibility. The Kappa statistic (Landis and Koch, 1977) was used to analyse the results. The Kappa Statistic is used as a measure of agreement beyond that solely due to chance. Zero represents random or chance agreement, and 1·00 represents perfect agreement.

Distribution of the DHC grades (Table 2)

A group of 332 (34·8 per cent) children were categorized in grades I or 2, 'no' or 'little' treatment need; 317 (33·2 per cent) children in grade 3, moderate treatment need; while 306 (32·0 per cent) were categorized in grades 4 or 5, 'great' or 'very great' treatment need. The distribution of the sample was similar to that recorded by Brook and Shaw (1989) in a study of 333 children aged 11·512·5 years. Sex distribution of Dental Health Component grades (Fig. 1)

There was a significantly higher percentage of females categorized in DHC grades I and 2, 38·5 per cent, compared with only 31·4 per cent of males. Conversely, there was a much lower percentage of females, 27·7 per cent, compared with 36·0 per cent of males, in the 'great' and 'very great' treatment need categories, grades 4 and 5 [SE diff % = 3·0 I, 0·0 I > P > 0·027]. These findings were again similar to those of Brook and Shaw's non-referred school population, of a comparable age group (Brook and Shaw, 1989).

180 A. Holmes

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Distribution of the scoring occlusal trait (Table 2)

Crowding was the most frequently scored occlusal trait overall (43·5 per cent) in the sample school population, with increased overjet the second most frequently scored trait in DHC grades 2, 3, and 4. Within grade 5 impeded eruption was the most frequently scored trait (77·1 per cent) followed by increased overjet (20 per cent) and clefts of the lip and/or palate (2·9 per cent).

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DHC: Intra-examiner reproducibility

The intra-examiner reproducibility of the DHC of the I.O.T.N. was very good. All six cases of discordance between the first and the second examinations occurred in the 'little' or 'moderate' treatment need categories, grades 2 and 3, and related to the degree of displacement of teeth. The 'anchoring effects' of the ends of scales are known to contribute to the consistency of estimated scores near the ends of scales (Freer et al., 1973), but the explanation for the six discordant cases probably related simply to measurement error. Cases with gross displacements were found to be much easier and quicker to record. The overall tendency to score lower at the second examination, as noted by Freer et al. [1973], was not substantiated in this study. The Aesthetic Component

The Aesthetic component of the I.O.T.N, like the DHC, was quick and easy for the examiner to use. In contrast the children, in some cases, found the concept behind the Aesthetic Component difficult to grasp. Children constantly attempted to match their dentition to the photographs, looking for specific morphological traits. This was especially true for children with fractured incisors, bilateral congenitally absent or pegshaped lateral incisors and the small number of class Ill malocclusions, all of whom found difficulty in the ~election of a photograph which best represented their degree of dental attractiveness.

Distribution ofthe Aesthetic Component scores (Figs 2 and 3)

The examining dentist rated 485 (50·7 per cent) children at the attractive end of the I 0-point scale, scores I, 2, or 3. This compared with 676 (70·8 per cent) child self-assessment Aesthetic Component scores at the attractive end of the scale. The discrepancy in the perception of dental attractiveness between orthodontists, general dental practitioners and patients has been noted in previous studies (Shaw, 1981). In both the dentist's and the children's Aesthetic Component ratings there were a higher proportion of females at the attractive end of the scale. Of the females, 74· 3 per cent rated themselves as I, 2, or 3 on the aesthetic scale compared with only 67·6 per cent of males. The results from both the Aesthetic and the DHC assessments seem to imply that, overall, the females in this survey had more attractive dentitions and less orthodontic treatment need than their male counterparts. Aesthetic Component: intra-examiner reproducibility

Very good intra-examiner agreement was achieved. The five ( 10·0 per cent) cases of discordance were all under-rated at the second examination. The effects of memory, experience, and improved skill in using indices have all been suggested as contributing to the discordance between first and second examinations (Freer et al., 1973). The effects of memory would have been unlikely to have influenced the results of this test of intraexaminer reproducibility in view of the length of time which elapsed between the first and second examinations, 6 weeks in total, with many other children screened in the intervening period. Aesthetic Component: agreement between dentist and child

Self-evaluation of dental aesthetics by the child

/nier-re/ationship between the dentist's aesthetic and DHC grades in percentages


Aesthetic score DHC ·












I 2 3 4 5

5·3 2·9 0·7 0·0 0·1

0·6 13·3 2-8 0·7 1·4

0·0 8·7 10·5 2·5 1·3

0·0 3·0 13·0 4·5 1·4

0·0 0·6 2·3 3-6 2·3

0·0 0·2 2·6 2·4 1·1

0·0 0·0 0·8 1·6 1·3

0·0 0·0 0·5 5·0 1·5

0·0 0·0 0·0 0·4 0·7

0·0 0·0 0·0 0·3 0·2

5·9 28·7 33·2 21·0 11·2













Orthodontic Treatment Needs

BJO August 1992


TABLE 4 Inter-relationship between the dentist's aesthetic and DHC scores in cumulative percentages Aesthetic score

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I 2 3 4 5

5·3 8·2 8·9 8·9 9·0

5·9 22·1 25·6 26·3 27·8

5·9 30·8 44·8 48·0 50·7

5·9 33·8 60·8 68·5 72-6

5·9 34·4 63·7 75·0 81·4

5·9 34·6 66·5 80·2 87·7

5·9 34·6 67·3 82·6 91·4

5·9 34·6 67·8 88·1 98·4

5·9 34·6 67-8 88·5 99·5

5·9 34·6 67·8 88·8 100·0

5·9 34·6 67-8 88·8 100·0













found only slight agreement with the examiner's objective aesthetic judgment. There was agreement between the examiner and the child on the aesthetic score rating in only 303 (31· 7 per cent) cases. Similar results have been found in other studies (Myrberg and Thilander, 1973; Ingervall and Hedegard, 1974; Lindsay and Hodgkins, 1983). However, Evans and Shaw (1987), using the same index as the current study, found the correlation for aesthetic ratings between the examiner and child to be much better, r=0·75, compared with r=0·38, for the current study. A group of 437 (45·8 per cent) children over-rated their level of dental attractiveness compared with the dentist's objective assessment. This over-rating by subjects was also observed in Brook and Shaw's (1989) study. There was an equal sex distribution of over-raters, 230 (45·7 per cent) males compared to 207 (45·8 per cent) females. 215 (22·5 per cent) children under-rated their level of dental attractiveness compared with the dentist's objective rating. There was again an almost equal sex distribution of under-raters, 120 (23·9 per cent) males and 95 (21·0 per cent) females. The child's rating was within one score of the examiners rating in 59·9 per cent of cases, compared with 70·0 per cent in Evans and Shaw's ( 1987) study. In a study by Tedesco et al. (1983) orthodontists consistently assessed the dental attractiveness of children as more attractive than the lay judges. The current study, in agreement with research by Shaw et al. (1975), found that the dental aesthetic ratings of orthodontists were less favourable than those of the children. Level of aesthetic treatment need (Tables 3 and 4)

The Dental Health and Aesthetic components of the I.O.T.N. were cross-tabulated to assess their inter-relationship, the results are shown in Table 3. A table of cumulative percentages (Table 4), which enables the potential percentage of patients at

varying levels of both dental health and aesthetic treatment need to be assessed, provides a more useful display of information. The present survey ran concurrently with the Community Dental Health Service's general dental survey. In the latter survey a total of 2438 children, aged 12·00-12·99 years, were examined, representing a 1-in-2 sample of the available population. The Community's survey included a subjective assessment of orthodontic treatment need by the examining senior dental officers, all of whom were experienced in epidemiological work and had been calibrated, but none of whom were orthodontists. Of the children in the Community Dental Health survey, 62·4 per cent were assessed as having satisfactory occlusions, 7·3 per cent were currently undergoing orthodontic treatment and 30·3 per cent, in the opinion of the examining dentist, definitely required an orthodontic assessment. If there was any doubt regarding the need for an orthodontic assessment the child was assessed as 'satisfactory'. The Community Dental Health survey's level of treatment need, when compared to the results in Table 4, corresponded to children with a DHC of 5 and an Aesthetic Component of 5 or greater (31· 5 per cent) or, alternatively, a DHC of 4 or 5, great and very great treatment need, and an Aesthetic Component of 7 or greater (33·5 per cent). The only realistic comparison that could be made with the current survey was with Brook and Shaw's ( 1989) survey of Manchester school children of a similar age, which used the same index. However, the examiners were not calibrated together in the use of the index so comparisons between the two surveys must be made with caution. If patients with aesthetic scores of 4 or less and DHC grades of2 or less are excluded for orthodontic treatment (33·8 per cent) 66·2 per cent of children could potentially require treatment. If, however, only those with aesthetic scores of 6 or greater and DHC grades 4 or 5 were selected for treatment, the


A. Holmes

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percentage falls to 36·3 percent. Using the samecutoffvalues, this compares with treatment need levels of 68·2 and 39·1 per cent, respectively, for Brook and Shaw's (1989) study. In the current study 41 (4·12 per cent) of the original sample of 996 children examined were undergoing active orthodontic treatment and were excluded from the study. Excluding children under active treatment, although not affecting the level of unmet treatment need, reduces the overall assessment of treatment need in the population under examination. In Brook and Shaw's (1989) study children undergoing active treatment were included in the study by obtaining the child's original study models and using them to record the I.O.T.N. scores.

Conclusion The prevalence of unmet orthodontic treatment need, at various levels of dental health and aesthetic need, has been assessed using the Index of Orthodontic Treatment Need. Only 5· 3 per cent of children, scoring I on both the dental health and aesthetic components of the Index, had absolutely no treatment need. A further 25· 5 per cent, scoring 3 or less on the aesthetic scale and 2 or less on the dental health scale had little requirement for treat1 ment. The level of need at which orthodontic treatment is offered can be adjusted to take into account variations in manpower and finance. If children with a DHC score of 3 or less and an Aesthetic Component score of 5 or less are excluded, the potential level of treatment need amongst the sample population was 36· 3 per cent.

Acknowledgements The author would like to acknowledge the help received from many sources, in particular Mr R. A. Heest~rman and his staff for their help in setting up this project and providing access and assistance for the school visits; and to Professor W. C. Shaw and his staff for their help in the use of the I.O.T.N. and in the analysis of the computer data.

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References Brook, P. H. and Shaw, W. C. (1989) The Development of an index of orthodontic treatment priority, European Journal of Orthodontics, ll, 309-320. Evans, R. and Shaw, W. C. (1987) Preliminary evaluation of an illustrated scale for rating dental attractiveness, European Journal of Orthodontics, 9, 314-318. Freer, T. J., Grewe, J. M. and Little, R. M. (1973) Agreement among the subjective severity assessments of ten orthodontists, The Angle Orthodontist, 43, 185-190. Gardlner, J. H. (1956) A survey of malocclusion and some aetiological factors in 1000 Sheffield schoolchildren, The Dental Practitioner, 6, 187-198. Haynes, S. (1970) The prevalence of malocclusion in English school children aged 11-12 years, Transactions of the European Orthodontic Society, 48, 89-98. lngervall, B. Hedegard, B. (1974) Awareness of malocclusion and desire of orthodontic treatment in 18-year old Swedish men, Acta Odontologica Scandinavica, 32,93-101. Landls, J. R. and Koch, G. G. (1977) The measurement of observer agreement for categorical dataBiometrics, 33, 159-174. Llndsay, S. J. E. and Hodgkins, J. F. W. (1983) Children's perceptions of their own malocclusions, British Journal of Orthodontics, 10, 13-20. Myrberg, N. and Thilander, B. (1973) Orthodontic need of treatment of Swedish school children from objective and subjective aspects, Scandinavian Journal Dental Research, 81, 81-84. Shaw, W. C. (1981) Factors influencing the desire for orthodontic treatment, European Journal Orthodontics, 3, 151-162. Shaw, W. C., Lewis, H. G. and Robertson, N. R. E. (1975) Perception of malocclusion, British Dental Journal, 138,211-216. Tedesco, L. A., Albino, J. E., Cunat, J. J., Green, L. J., Lewls, E. A. and Slakter, M. J. (1983) · A dental-facial attractiveness scale. Part I reliability and validity, American Journal of Orthodontics, 83, 38-46. Todd, J. E. and Dodd, T. (1985) Children's dental health in the United Kingdom 1983, Office Population Censuses and Surveys, Social Survey Division, Her Majesty's Stationery Office, London.

The prevalence of orthodontic treatment need.

The prevalence of unmet orthodontic treatment need amongst 955 12-year-old Sheffield children has been assessed using the Index of Orthodontic Treatme...
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