Orthodontic treatment needs in 10–12-year-old school children from Sulaimani City, Iraq: a cross-sectional study

Abstract

Background

Malocclusion is a prevalent oral health concern worldwide, ranking third after dental caries and periodontal disease. Early identification and intervention in childhood can prevent its progression into adulthood. The Index of Orthodontic Treatment Need (IOTN) is widely used to assess malocclusion severity. However, global studies using the IOTN have reported varying malocclusion prevalence rates, which are influenced by socioeconomic and ethnic factors. This study aimed to examine the orthodontic treatment needs among Iraqi children aged 10–12.

Methods

A total of 384 children (173 boys and 211 girls) were randomly selected from four distinct regions in Sulaimani, Iraq. Eligibility criteria included Iraqi children aged 10–12 years with no history of orthodontic treatment, non-nutritive sucking habits, or craniofacial anomalies. Evaluations took place in school environments, using criteria from the American Board of Orthodontics to assess overjet, reverse overjet, overbite, anterior openbite, and buccal crossbite. Malocclusion severity was categorized using the Dental Health Component of the IOTN. Data analysis included chi-square testing, and 95% confidence intervals to interpret findings.

Results

Most children had mild treatment needs (Grade 2: 36.2%), followed by no treatment required (Grade 1: 31.3%) and moderate needs (Grade 3: 24.5%). More severe cases were less common, with Grade 4 (4.7%) and Grade 5 (3.4%). Overbite was the most prevalent malocclusion requiring treatment, while overjet had the lowest demand. No significant gender differences were found (p > 0.05).

Conclusions

Mild to moderate malocclusion was prevalent, with overbite and crossbite being the most frequent conditions requiring treatment. Overjet exhibited the lowest treatment demand, and gender differences were not significant, suggesting equal applicability of orthodontic programs to both boys and girls.

Trial registration

Not applicable.

Introduction

In recent years, there has been an increasing concern about dental appearance and function even during childhood. One significant issue affecting both esthetics and function is malocclusion—a developmental disorder characterized by misalignment between teeth and the dental arches. According to the World Health Organization (WHO), malocclusion ranks as the third most prevalent oral health issue, following dental caries and periodontal disease [1,2,3]. This high prevalence highlights the importance of early diagnosis and treatment in primary and mixed dentition to prevent long-term consequences on both appearance and function [4, 5]. Moreover, the WHO advocates regular epidemiological surveys of major oral health issues, including malocclusion, to ensure adequate treatment infrastructure and specialist training [6, 7].

In line with the importance of early diagnosis, various indexes have been created to evaluate malocclusion severity and treatment needs. The Index of Orthodontic Treatment Need (IOTN), introduced by Brook and Shaw in 1989, is widely used in clinical practice due to its simplicity, reliability, and ease of application [8, 9]. The IOTN assesses both objective and subjective orthodontic needs through two components [10]: the Dental Health Component (DHC), a five-level index, and the Aesthetic Component, a 10-point scale using color photographs to depict different levels of dental attractiveness [2, 11].

However, studies using the IOTN to predict malocclusion prevalence and orthodontic treatment needs across countries have shown varied results, ranging from 32 to 93% [6, 12]. This variability can be attributed to factors such as age, social status, ethnic background, and data collection techniques [5, 13, 14].

Notably, there is a lack of specific data on orthodontic treatment needs in the Iraqi population. Therefore, this study aims to assess the orthodontic treatment needs of Iraqi schoolchildren, based on malocclusion severity as graded by the DHC of the IOTN. It is hypothesized that a significant portion of Iraqi children may require orthodontic intervention, with malocclusion prevalence potentially differing from that in other populations due to socioeconomic and ethnic variations. This study seeks to provide valuable data to support healthcare policies and enhance early intervention for malocclusion.

Methods

This cross-sectional study was conducted to assess the orthodontic treatment needs among schoolchildren aged 10–12 years in Sulaimani city, Iraq. This age group represents the late mixed and early permanent dentition stages, making it ideal for assessing malocclusion before skeletal maturity is reached. Additionally, early intervention at this stage can be beneficial.

A simple random sampling technique was used to select children from four geographic areas (Northern, Southern, Eastern, and Western) of Sulaimani city, and participants were selected randomly from school records. Each area contributed four schools—three public and one private—selected during the period between November 2023 and May 2024. A randomized selection process minimizes selection bias and random sampling is an established epidemiological method that strengthens the study’s statistical power and generalizability. Additionally, including children from different geographic regions of Sulaimani ensures a diverse sample that reflects variations in socioeconomic status and healthcare accessibility. This enhances the external validity of the study by making the findings applicable to the broader population.

The exclusion criteria included students who were not within the age limit (10–12 years), uncooperative children, those with a previous history of orthodontic treatment, history of non-nutritive sucking habits (fingers and pacifiers), those with craniofacial anomalies, non-Iraqi people, and those with missing data. Excluding participants with previous orthodontic treatment prevents confounding effects, as previous interventions could distort the true prevalence of malocclusion. Furthermore, non-nutritive sucking habits are significant environmental factors contributing to malocclusion. However, the primary aim of our study was to assess malocclusion without external behavioral influences, ensuring that the observed malocclusions reflect inherent developmental patterns rather than acquired habits. Also, children with congenital craniofacial anomalies (e.g., cleft lip and palate) have unique orthodontic needs that require specialized assessment. Excluding these cases ensures that the study focuses on typical orthodontic treatment needs rather than highly specialized interventions.

To calculate the sample size for this study General Power Analysis Software (G Power) software (version 3.1) was used. A two-tailed test was used to compare the proportions of orthodontic treatment needs between two independent groups. The test family selected was “Exact”, and the statistical test chosen was “Proportions: Inequality, two independent groups (unconditional)”.

To ensure an adequate statistical power, the following parameters were used:

• Odds Ratio (OR): 2.2.

• Proportion (p2): 0.58.

• Significance level (α): 0.05.

• Power (1-β): 0.95.

• Allocation ratio (N2/N1): 1.

Based on these inputs, G*Power calculated a required sample size of 384 participants. This sample size ensures a statistical power of 0.95, minimizing the risk of a Type II error while maintaining sufficient precision for detecting meaningful differences.

Ethical approval

was obtained from the Ethics Committee of the College of Dentistry at the University of Sulaimani (protocol code 34, registration number 23/150, dated 27 February 2023), and we ensured that all ethical guidelines, including those outlined in the 1975 Declaration of Helsinki, were followed throughout the study. Also, informed consent was obtained from the parents or guardians of all participating children before any data collection. Informed consent from parents/guardians ensures the protection of children’s rights and complies with research ethics guidelines. As part of the consent process, the purpose of the study was explained, and permission was asked for the examination. Additionally, demographic information, including age, gender, and geographical area, as well as data on previous history of orthodontic treatment and non-nutritive sucking habits, were gathered.

Data collection was performed in school settings by a team of trained dental professionals. All students were examined using a disposable mirror, explorer, and a sterile metal gauge. Children were seated on chairs, and a portable headlight was used for visibility during the examination. To ensure the consistency and reliability of the clinical assessments, all examiners underwent training and calibration sessions before data collection. Intra-operator reliability was assessed using Cohen’s kappa statistic, and the values indicated strong agreement (> 0.85) across repeated measurements. Also, inter-operator reliability was evaluated by comparing assessments between multiple trained examiners, yielding a kappa value of > 0.80, reflecting high consistency in malocclusion grading.

The orthodontic parameters were evaluated according to the American Board of Orthodontics (ABO) criteria: The following parameters were assessed [15]:

• Overjet: Measured between the labial surface of the most lingually positioned mandibular incisor and the middle of the incisal edge of the most labially positioned maxillary incisor. The greatest overjet was recorded.

• Reverse Overjet: Measured from the labial surface of the maxillary incisor to the middle of the incisal edge of the mandibular incisor.

• Overbite: Determined by the vertical overlap of two antagonistic incisors (central or lateral), with the greatest overbite recorded.

• Anterior Openbite: Quantified by measuring the distance between the incisal edges of the maxillary and mandibular incisors, recording the greatest gap.

• Buccal Crossbite: Identified when the palatal cusp of the maxillary posterior tooth or teeth occluded palatally to the buccal cusp of the opposing mandibular tooth/teeth.

Following the examination, each subject was assessed for orthodontic treatment need using the IOTN-DHC, which was selected for its ability to provide an objective measure of malocclusion severity, allowing for standardized comparisons with international studies. The DHC grades malocclusion on a scale of 1 to 5, with higher scores indicating a greater need for orthodontic treatment, as detailed in Table 1 [16]. IOTN-DHC was selected to provides an objective measure of malocclusion severity, facilitating comparisons with international studies. In this study, malocclusion classification was primarily based on the IOTN-DHC, ensuring alignment with internationally recognized standards, particularly those commonly used in British orthodontic assessments. While measurement criteria from the ABO Discrepancy Index were incorporated as a supplementary diagnostic reference to enhance the assessment of malocclusion severity. However, the primary classification and interpretation of orthodontic treatment needs relied on the IOTN-DHC, ensuring consistency with established protocols for evaluating malocclusion prevalence and treatment priority.

Table 1 Orthodontic treatment need based on IOTN-DHC classification [16]

Statistical analysis

The data were analyzed using Statistical Package for the Social Sciences (SPSS) software (version 25.0), and the significance level was set at p < 0.05 for all analyses. As the data was normally distributted according to the Shapiro-Wilk test, descriptive statistics (mean, frequencies, and percentages) were used to summarize demographic characteristic of gender, as well as the orthodontic parameters (overjet, reverse overjet, overbite, anterior open bite, and buccal crossbite). Also, to examine associations between gender and the severity of malocclusion (IOTN-DHC grades), Chi-square tests were employed. Furthermore, sensitivity analyses were conducted to check the robustness of the findings by running the analysis with and without imputed data to evaluate the impact of missing data on the results. Interaction analyses were performed using a logistic regression model to assess the effect of gender and its interaction with different malocclusion types on the need for orthodontic treatment.

Results

Out of an initial pool of 506 participants, 122 children were excluded due to exclusion criteria, resulting in a final study population of 384 participants (173 males and 211 females) (Fig. 1).

Fig. 1

Flow diagram representing the participant selection process

Distribution of orthodontic treatment needs

Table 2 shows the distribution of orthodontic treatment needs based on the IOTN-DHC. Most children had mild treatment needs (Grade 2: 36.2%), followed by those requiring no treatment (Grade 1: 31.3%) and those with moderate needs (Grade 3: 24.5%). More severe cases were less common, with Grade 4 (4.7%) and Grade 5 (3.4%).

There were a relatively balanced distribution of orthodontic treatment needs between genders, with a slightly higher proportion of females in Grades 2, 3, and 4. However, the chi-square test for gender distribution across the IOTN grades indicated no statistically significant difference (p > 0.05).

Table 2 Distribution of orthodontic treatment need by gender

Prevalence of malocclusion types and treatment needs

Table 3 presents the distribution of different malocclusion types and treatment needs, the results are as follows:

• Overjet had the highest prevalence among children who required no treatment (Grade, 22.7%).

• Overbite was the most common malocclusion requiring slight treatment (Grade 2, 17.2%).

• Moderate treatment need (Grade 3) was most frequently associated with overjet (6.9%) and overbite (11.9%).

• More sever malocclusion (Grade 4 and 5) were predominantly seen in cases of openbite (5.2%) and crossbite (3.2%), indicating a greater need for orthodontic intervention.

• No statistically significant gender differences were found for any malocclusion types (p-values: overjet (0.197), reverse overjet (0.427), overbite (0.476), open bite (0.742), and crossbite (0.477)).

Table 3 Prevalence and gender comparison of malocclusion types based on IOTN-DHC grades

Overall need for orthodontic treatment

Table 4 provides a summary of overall treatment needs by malocclusion type:

• Overbite had the highest need for orthodontic treatment (97.93% prevalence, 95% CI: 95.61 − 100.25%).

• Crossbite also exhibited a high treatment necessity (80.00% prevalence, 95% CI: 62.47 − 97.53%).

• Reverse overjet (65.22%), open bite (60.00%), and overjet (56.85%) followed, indicating moderate to high orthodontic treatment demand.

• A statistically significant difference was found in the prevalence of orthodontic treatment needs across different malocclusion types (p = 0.002).

Table 4 Overall need for orthodontic treatment based on malocclusion type

The bar chart (Fig. 2) further illustrates these findings, highlighting overbite as the malocclusion type with the highest need for orthodontic treatment, while overjet shows the lowest need.

Fig. 2

Bar chart

Sensitivity and interaction analyses

To ensure the robustness of the findings:

• Sensitivity analysis was conducted using multiple imputation to handle missing data, revealing no substantial differences in results.

• Exclusion of outliers did not significantly alter the outcomes.

• Interaction analysis using a logistic regression model assessed whether gender modified the relationship between malocclusion type and treatment need. No significant interaction effects were observed (p > 0.05), confirming that gender was not a major determinant of treatment necessity (Fig. 3).

Fig. 3

Logistic regression plot showing the interaction between gender and malocclusion type on the need for orthodontic treatment

Discussion

This cross-sectional study aimed to assess orthodontic treatment needs in children aged 10–12 years from Sulaimani City, Iraq. This age range was selected because most children are in the late mixed or early permanent dentition stages, allowing for a more accurate assessment of malocclusion. At this stage, occlusion becomes stable, providing a clearer picture of any orthodontic issues that may require intervention [17].

A simple random sampling technique was used to ensure a representative sample from different geographic areas, covering both public and private schools. The inclusion of children from various socioeconomic backgrounds enhances the generalizability of the findings. The sample size of 384 was determined using GPower software, ensuring adequate statistical powe [18]. The use of trained professionals and a standardized protocol for assessments in familiar school environments minimized anxiety among participants and ensured reliable data collection [19].

The results indicated that the majority of children fell into Grade 2 (36.2%), suggesting mild orthodontic treatment needs, followed by Grade 1 (31.3%) and Grade 3 (24.5%). Only a small proportion of children had more severe treatment needs in Grades 4 and 5 (4.7% and 3.4%, respectively), a pattern consistent with other studies [20, 21]. While the research conducted by Al-Huwaizi and Rasheed, found that 10.3% of 13-year-old Iraqi Kurdish children had mandatory orthodontic treatment needs based on the Dental Aesthetic Index [22]. The finding suggest that severe malocclusion is consistently less frequent across various populations, though the overall need for orthodontic care remains an important public health consideration.

Regarding gender distribution, this study found no statistically significant difference between males and females (p > 0.05), aligning with previous research [23, 24]. For instance, a study in Southwestern Ethiopia reported no significant gender differences in orthodontic treatment needs [25]. Similarly, an epidemiological study on orthodontic treatment needs in private clinics in Sulaimani City by Amin et al., 2014 found that females were more likely to seek orthodontic treatment, but there were no significant gender-based differences in malocclusion severity [26]. This suggests that gender may not be a critical factor in determining orthodontic needs during childhood, allowing treatment planning and resource allocation to focus on the overall prevalence of malocclusion rather than gender-based differences.

In terms of malocclusion types, overbite is the most frequent malocclusion requiring treatment followed by crossbite. Given the consistency of these results with international data, our study supports the notion that overbite and crossbite are the most prevalent and should be the focus of early intervention [17].

Moreover, the study found a statistically significant difference in treatment need across malocclusion types, indicating that these differences are not random and underscoring the importance of tailored orthodontic care based on specific malocclusion types.

Despite the valuable insights gained, this study has several limitations. The IOTN-DHC was used as the primary classification tool, although it is an effective tool, may not fully capture the complexity of orthodontic needs. Additionally, the cross-sectional study design restricts the ability to draw causal inferences about the progression of malocclusion over time. Furthermore, the study’s geographic focus on Sulaimani City, while representative of Iraqi schoolchildren, may not be fully generalizable to other regions of Iraq. Future studies should adopt longitudinal designs and incorporate multiple assessment tools, including Angle’s Classification, to provide a more comprehensive understanding of orthodontic treatment needs in Iraq.

Conclusions

Mild to moderate orthodontic treatment needs were prevalent among 10–12-year-old children in Sulaimani City, Iraq, with severe cases being less frequent. Overbite and crossbite were the most common conditions requiring orthodontic intervention, whereas overjet exhibited the lowest treatment demand. No significant gender differences were found, suggesting that orthodontic treatment programs should be equally implemented for both males and females.