|Year : 2021 | Volume
| Issue : 1 | Page : 38-44
Development and comparison of the new index with DAI for evaluating orthodontic treatment need in high caries prevalence community: A diagnostic test study
Thearmontree Angkana1, Thuput Sudarat2, Suntornlohanakul Supanee3
1 Improvement of Oral Health Care Research Unit, Department of Preventive Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand
2 Department of Preventive Dentistry, Program in Oral Health Science (Orthodontics), Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand; Private Dental Clinic, Meang, Phatthalung, Thailand
3 Department of Preventive Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai, Songkhla, Thailand
|Date of Submission||03-May-2020|
|Date of Decision||23-May-2020|
|Date of Acceptance||20-Aug-2020|
|Date of Web Publication||28-Jan-2021|
Dr. Thearmontree Angkana
Department of Preventive Dentistry, Faculty of Dentistry, Prince of Songkla University, Hat Yai 90112, Songkhla.
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study was to develop an index for evaluating orthodontic treatment need called “Community Orthodontic Treatment Need Index (COTN)” and to preliminarily compare its accuracy and reliability with Dental Aesthetic Index (DAI). Materials and Methods: This diagnostic test study includes three steps. First and second steps were related to develop the index (COTN) and assessing its accuracy and reliability in dental models. The 110 orthodontic dental models were randomly selected from the pooled dental models of 12–14-year-old children who came for orthodontic screening at the University Orthodontic Clinic. Seven experienced orthodontists assessed orthodontic treatment needs in all 110 dental models (gold standard). Eighty dental models were randomly selected from these 110 models to develop the index by creating algebraic equations using discriminant analysis. Another 30 dental models were evaluated for accuracy and intra-examiner reliability of the two indexes. The last step compared reliability and time consuming of indices in the community. Two examiners assessed 28 schoolchildren aged 12–14 years who were purposively selected using two indices at school. Kappa coefficient, sensitivity, specificity, and paired t test were calculated. Results: COTN contains both anterior and posterior teeth components. It was more likely to have better accuracy and intra-examiner reliability in evaluating orthodontic treatment needs in dental models than DAI (sensitivity + specificity = 1.67 vs. 1.56, kappa = 0.811 vs. 0.689, respectively). Nevertheless, COTN was comparable to DAI for reliability and time consuming when used in the community. Conclusion: This new index (COTN) could be an alternative index for evaluating orthodontic treatment need in high caries prevalence community.
Keywords: Community Orthodontic Treatment Need Index (COTN), Dental Aesthetic Index (DAI), High Caries Prevalence Community, Orthodontic Treatment Need Index
|How to cite this article:|
Angkana T, Sudarat T, Supanee S. Development and comparison of the new index with DAI for evaluating orthodontic treatment need in high caries prevalence community: A diagnostic test study. J Int Oral Health 2021;13:38-44
|How to cite this URL:|
Angkana T, Sudarat T, Supanee S. Development and comparison of the new index with DAI for evaluating orthodontic treatment need in high caries prevalence community: A diagnostic test study. J Int Oral Health [serial online] 2021 [cited 2022 Jan 27];13:38-44. Available from: https://www.jioh.org/text.asp?2021/13/1/38/308349
| Introduction|| |
Malocclusion is not a disease, but it is rather the variation from normal. However, it cannot be completely separated from the oral health. Children with malocclusion could have functional impairment of masticatory system and speech, psychosocial problems as well as the quality of life.,, Since the management of malocclusion needs specially trained personnel and has a high cost, the determination of orthodontic treatment need is crucial for setting the priority of treatment and budget allocation.
Orthodontic treatment need index is the tool used for identifying patients as having need or no need for orthodontic treatment. It has been used for many purposes. For example, many countries use this type of index to determine which patient is eligible for government-subsidized treatment, and furthermore to identify what level of copayment is required. They are also useful for determining the priority of orthodontic treatment. It was found that utilizing this type of index is extremely important for governmental budget calculations and workforce planning for orthodontists.
Currently in Thailand, there is no clear or up-to-date statistics on the extent of orthodontic treatment need. Even though there have been several surveys, they were generally limited to malocclusion problems, and did not really identify orthodontic treatment need.,,,,,, To determine the prevalence of orthodontic treatment need, an appropriate orthodontic treatment need index is required.
Since 1959, there had been attempts to develop different quantitative indices to measure orthodontic treatment need for using in both clinical and community settings. There are many indices regarding the need for orthodontic treatment. Those which are popular worldwide include Index of Orthodontic Treatment Need (IOTN), Index of Complexity, Outcome and Need (ICON), and Dental Aesthetics Index (DAI).
DAI was developed by Cons et al. The index is based on patient’s aesthetic and psychosocial factors. It assesses 10 characteristics, which are multiplied by the relevant weightings, and then summed for a final DAI score. The final scores then are placed into four levels of orthodontic treatment need. DAI was found to be highly reliable, easy, and quick to use, and at low cost.,, It has been demonstrated by many studies to have a high level of accuracy and has been accepted by many organizations. DAI has been used in many Asian and developing countries, such as Thailand, Malaysia,, Nigeria, South Africa, and Brazil. The assessments of DAI can be performed quickly, easily, and at low cost in the community., Moreover, it has been recommended by the World Health Organization.
However, DAI showed to have better accuracy in the developed countries like the US, than that from the developing such as the study in Brazil. Similarly, DAI may be less accurate in Thailand and other developing countries where very high prevalence of caries and loss of posterior teeth were found.,, Loss of posterior teeth can cause malocclusion by changing incisal relationship, extrusion of opposite teeth, and drifting of adjacent teeth., DAI ignores the conditions such as molar missing, buccal crossbite, dental midline deviation, deep overbite, impacted teeth, or posterior crossbite. Some of those characteristics are highly prevalent in Thailand., and other developed country.
Therefore, it is interesting to evaluate the accuracy of DAI together with an attempt to develop more valid index for evaluating patients’ orthodontic treatment need at an early stage of permanent teeth in the high caries prevalence community like Thailand. This new index was developed based on DAI and included additional components that are prevalent in children with high caries. This study aimed to develop a new index for evaluating orthodontic treatment need in the high caries prevalence community called “Community Orthodontic Treatment Need Index (COTN)” and preliminarily evaluate its accuracy and reliability by comparing to those of DAI. The null hypothesis was that the new index (COTN) is comparable to DAI for evaluating orthodontic treatment need.
| Materials and Methods|| |
Setting and design
This study is a diagnostic test study. It was divided into three steps: (1) Development of the new index: COTN, (2) Comparing the accuracy and reliability of COTN with DAI in the dental models, and (3) Feasibility studies of using COTN in the community. The study was conducted during 2017–2018.
In steps 1 and 2, the samples were 110 dental models that were randomly chosen from the pooled orthodontic dental models of children aged 12–14 years who came for orthodontic screening at the Orthodontic Clinic, Faculty of Dentistry, Prince of Songkla University, Hat Yai district, Songkhla province, Thailand during 2007–2017. These 110 dental models were then randomly divided into two groups comprised of 80 models (step 1) and 30 models (step 2). The sample size for step 1 for the three-group respondents in discriminant analysis with moderate effect size, α = 0.05 and β = 02 which can have up to 10 predictors is at least 78.
In addition, twenty-eight 12–14-year-old students who were purposively chosen from a school in Hat Yai, Songkhla and their parents returned the consent forms with permission were included in step 3.
Study method and observational parameters
The gold standard of the orthodontic treatment need in this study was performed by seven experienced orthodontists on 110 dental models. The seven orthodontic experts were certified and graduated from various countries, both Thailand and abroad. The assessments were graded into three categories based on orthodontic treatment need: (1) No or slight need, (2) Moderate need, and (3) High need. To formulate the gold standard, a majority or at least four of seven experts had to concur on the level of orthodontic treatment required. The results of these 110 dental models were then used for the study in steps 1 and 2, respectively.
Step 1: Development of the new index: COTN
Twenty-two characteristics of malocclusion were selected; 10 were from DAI, and an additional six variables were taken from other indices, (validation of the index) and another six were malocclusions that affect mastication and high prevalence among Thai children., The additional 12 characteristics are as follows: (1) Sum of anterior spacing, (2) Anterior spacing, (3) Upper anterior crowding, (4) Anterior crossbite, (5) Vertical anterior overbite, (6) Upper and lower dental midline deviation >4 mm, (7) Posterior spacing (number of segments), (8) Posterior spacing (mm), (9) Missing molar, (10) Posterior crossbite, (11) Posterior crowding, and (12) Posterior open bite.
The standardization for the examination of all malocclusion characteristics between the researcher and the orthodontic specialist was done on 32 dental models prior to data collection. Assessments were performed twice, at a 2-week interval, and alternating the sequence of dental models to reduce recall bias. The inter- and intra-examiner reliabilities presented with kappa coefficients of 0.741 and 0.653, respectively, which are considered to be good.
Eighty dental models which had been examined for orthodontic treatment needs as gold standards by orthodontic experts were chosen at random. Measurement of the 22 variables was performed on these models by one of the researchers.
Step 2: Comparing the accuracy and reliability of COTN, with DAI in the dental models
The researcher examined the remaining 30 dental models by applying both COTN and DAI. The examinations were performed on two separate occasions, 4 weeks apart. The sequence was varied on the secondary examinations to reduce recall bias.
Step 3: Feasibility study of using COTN in the community
A general dentist was trained to use COTN on the dental models for an hour and a half. Consequently, twenty-eight 12–14-year-old students who were randomly chosen from a school in Hat Yai, Songkhla and their parents returned the consent forms with permission were examined by the researcher and the trained dentist. The examinations were performed under natural light, using a Michigan probe. Inter- and intra-examiner reliabilities were conducted on these 28 samples between researcher and trained dentist and between the two consecutive examinations of the trained dentist (2 weeks apart), respectively.
The Statistical Package for the Social Sciences (SPSS) Statistics Base, version 17.0, for Windows EDU (SPSS, Chicago, Illinois, USA) was used for the analysis.
Step 1: Relationship between the 22 variables and the gold standard was calculated using Spearman’s rank correlation coefficient. An equation was then formulated for the new index using the Stepwise discriminant analysis technique.
Step 2: Intra-examiner reliability was evaluated using kappa analysis. The accuracy of both indices COTN and DAI was assessed using sensitivity and specificity with 95% confidence interval, as well as sum of sensitivity and specificity. The cutoff levels of the two indices shown in [Table 1].
Step 3: Kappa analysis was performed to determine the inter- and intra-examiner reliability. To compare the average time used in each index, paired t test was conducted. All analyses were tested at the significance level of 0.05 and 0.01.
| Results|| |
According to the orthodontic experts (gold standard), the majority of the subjects (55.5%) had high need of orthodontic treatment. While the proportions were similar for those requiring moderate and little or no need of orthodontic treatment (23.6% and 20.9%, respectively).
Step 1: Development of the new index: COTN
In the process of developing the index, the variables were firstly grouped based on the interrelationship within 22 initial variables identifying four groups within which the variables measured malocclusion similarly. These variables were then merged into four groups [Table 2]. Only those malocclusion characteristics that were significant and/or had highest correlation with the gold standard were chosen from each group. Five variables from four groups were chosen. They were: (1) Anterior spacing, (2) Largest maxillary irregularity, (3) Upper anterior crowding, (4) Anterior maxillary overjet, and (5) Posterior spacing (number of segment).
|Table 2: Inter-correlation of the malocclusion characteristics and their correlations to the gold standard|
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The other eight variables came from the remaining characteristics that could not be grouped, as there was no correlation with any of the others. One variable, upper and lower dental midline deviation >4 mm. which was not present in the sample, was excluded. Totally, there were 13 independent variables forming a multiple linear equation for discriminant analysis.
The accuracy of the equation with 13 variables was 76.3%. However, after performing the stepwise technique, there were only five independent variables left, namely: (1) anterior spacing, (2) largest maxillary irregularity, (3) anterior maxillary overjet, (4) anterior crossbite, and (5) anterior–posterior molar relation, with an accuracy of 68.8%.
It was noticed that the model with five variables did not include important malocclusion characteristics, especially those that affect the normal function and traumatic occlusion. These include posterior crossbite, posterior crowding, posterior spacing, and vertical anterior overbite. The equation was thus formulated using nine variables (5+4 additional variables) which increased the accuracy to 75%. The equation which included nine variables appeared to be relatively accurate compared to the original 13 variable equation (75% vs. 76.3%).
One variable was anterior spacing which affects only aesthetics was removed since it was less prevalent in Asian population.,,, and the index focused on factors affecting occlusion or function. This results in a model of eight independent variables, producing accuracy of 73.8%, which is only inferior to the model with nine variables by 1.2%. The eight variables of COTN are made up of four relevant to anterior teeth, and four relevant to posterior teeth. Of these eight variables, only three variables originated from DAI.
The final index consists of eight variables or components which are (1) anterior crossbite (AC), (2) largest maxillary irregularity (MI), (3) vertical anterior overbite (OB), (4) anterior maxillary overjet (MO), (5) posterior crossbite (PC), (6) posterior crowding (PCd), (7) posterior spacing (PS), and (8) anterior–posterior molar relationship (MR). The COTN score comes from the sum of eight variables which each variable multiplied by its respective coefficient in each of the three equations shown in [Table 3], which then provides a single score for each equation. The equation which produces the highest score becomes an indicator of the patient’s orthodontic treatment need.
|Table 3: Equations and accuracy for Community Orthodontic Treatment Need Index (COTN) using stepwise discriminant analysis|
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For the convenience in applying the index, the computer software was developed to assist in processing data and presentation of results of the two indices: COTN and DAI. Once the computation is completed, the data are stored in the database. The program can also display the results of orthodontic treatment need levels grouped by age and gender, as well as the average examination durations.
Step 2: Comparing the accuracy and reliability of COTN, with DAI in the dental models
The preliminary evaluation of accuracy and reliability of the new index (COTN) was done against that of DAI through examinations of 30 dental models. COTN presented higher intra-examiner reliabilities than did of DAI (kappa = 0.811 and 0.689, respectively). [Table 4] shows that COTN demonstrated higher overall accuracy and sensitivity than DAI when identifying orthodontic treatment need. Nevertheless, the confidence intervals of the specificity in identifying need levels are wide.
|Table 4: Sensitivity, specificity, and their 95% confidence intervals of orthodontic treatment need of COTN and DAI|
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Step 3: Feasibility study of using COTN in the community
The final step was to determine the feasibility of applying the new index, COTN in the community. It was found that both inter- or intra-examiner reliabilities of COTN were higher than those of DAI. However, the average examination time for COTN was the same as that of DAI (COTN = 73±18 sec vs. DAI = 73±16 sec) [Table 5].
|Table 5: Intra- and inter-examiner reliability and time consuming for indices COTN and DAI in the community|
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| Discussion|| |
The new index, COTN, was developed for use in assessing orthodontic treatment need in early permanent dentition of children in the high caries prevalence community, mostly in developing countries. COTN assessment can be performed using standard equipment, such as periodontal probes, particularly the Michigan probe. Michigan probe has a scale of 1 mm, providing an accurate assessment and is easy to use in the oral cavity. Due to simplicity, COTN can be used by general dentists with the basic equipment. It showed relatively good accuracy and reliability.
Considering the characteristics used for evaluation, DAI places more emphasis on the anterior teeth, while COTN provides a more balanced evaluation of both anterior and posterior teeth. The malocclusion characteristics used for COTN are more focused on occlusion or function than DAI, particularly on traumatic occlusion such as vertical anterior overbite and posterior crossbite, which are not considered in DAI.
The COTN index uses a similar methodology to DAI in which the evaluation is derived from an aggregate of a number of characteristics. However, COTN decides the orthodontic treatment needs level on the highest value among those of the three equations, whereas DAI uses the cutoff points of the total score. Different cutoff points of DAI gave different results.
This study found that the time required to assess the orthodontic treatment need in dental models for the new index (COTN) was significantly lower than that of DAI. This is because COTN index has fewer assessment elements. However, when performing in the community, COTN took a similar time to that of DAI. This was attributed to the difficulty in examining the posterior teeth in the oral cavity, compared to that in the dental models. In fact, COTN has more components in posterior teeth than DAI (COIN = 4 components, DAI = 1 component).
In the dental models, the intra-examiner reliability demonstrated by kappa coefficients of COTN was 0.81, which is considered to be almost perfect agreement and is higher than those of DAI in this study and in the Brazilian study. However, when using in the community, both COTN and DAI were less reliable than in the dental models. This might be due to greater limitations when using in the community. For example, examinations of posterior teeth are more exhausting in natural light, and guiding the child into centric occlusion is difficult.
Regarding the use of the new index (COTN) and DAI in the community, this study discovered that both intra- and inter-examiner reliabilities between orthodontist and general dentist of COTN were higher than those of DAI. However, it was lower than that of DAI in the study by Otuyemi et al. This is potentially due to the examiners in the study of Otuyemi et al., being trained and standardized on the subjects before testing, whereas the dentist in this study had been trained on dental models only. Nevertheless, the intra-examiner reliability for COTN in this study was considered to be at an acceptable level (kappa = 0.679).
This preliminary study showed that COTN index had higher sensitivity than that of DAI in evaluating patients for whether orthodontic treatment was necessary or not (COTN = 0.92 vs. DAI = 0.81). This means that when using COTN index to access children who need orthodontic treatment, it is more likely to correctly determine them to be in the needed group. In addition, it has less chance to miss the children who really need orthodontic treatment.
The higher overall accuracy and sensitivity of COTN in this population may be due to the fact that it contains more factors relating to malocclusion in the posterior teeth than DAI. It has been known that most functional problems that lead to the need for orthodontic treatment are affected by malocclusions in posterior teeth.,, And caries and tooth loss in posterior teeth are highly prevalent in Thai children and other developing countries,,, which can cause malocclusion in the posterior regions.
Using high-accuracy index to screen and refer the children for orthodontic treatment does not only assist in budget saving, but also saves time of patients and orthodontists from unnecessary appointments. For those reasons, the COTN index is more likely to be favorable for use in the low-income or developing countries where access to orthodontists is restricted and funding is low. Nevertheless, these preliminary results showed wide confidence intervals especially for the specificity values. These are due to small sample size. Further study with larger sample size should be conducted.
The new index, COTN, evaluates the characteristics of malocclusion in both anterior and posterior teeth. It mainly focuses on abnormalities in functional occlusion, rather than aesthetics. In the high caries prevalence community, COTN was more likely to have higher sensitivity but the same specificity compared to DAI in evaluating orthodontic treatment need. In addition, both the inter- and intra-examiner reliabilities of COIN were demonstrated to be better than those of DAI. Nevertheless, the examination of both indexes consumed similar time when used in the community.
Therefore, COTN may be an alternative index for use in the community or population with high caries prevalence to assess orthodontic treatment need in early stage of permanent dentition.
Future studies on a larger sample size both in the community and in the clinic are recommended to ensure the accuracy of this new index. Also, evaluating the use of this new index by other dental personnel would be useful.
The authors would like to thank Dr. Alan Geater for his valuable suggestions and Mr. Phusak Kunvale for developing the computer program for COTN.
Financial support and sponsorship
This study was supported by research funding from Graduate School, Prince of Songkla University, Thailand.
Conflicts of interest
All authors contributed to study conception, data collection, data acquisition, manuscript writing, and approved the final version of the manuscript for publication. Only Dr. Thearmontree and Dr. Thuput took part in data analysis and data interpretation.
Ethical policy and institutional review board statement
This study was approved by the Research Ethics Committee (REC) Faculty of Dentistry, Prince of Songkla University, Thailand on 17 May 2018 (Approval number: EC6101-04-P-LR).
Declaration of patient consent
All the procedures performed in the study, such as written informed consent, freedom to withdraw, and publication of data only for research and educational purpose were per the ethical guidelines laid down by the Declaration of Helsinki (2013).
Data availability statement
The data that support the findings of this study are available from the corresponding author, on reasonable request.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]