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Year : 2020  |  Volume : 31  |  Issue : 6  |  Page : 967-970
The mean overjet in libyan children and the relationship between increased overjet and incisors trauma

1 Department of Pediatric Dentistry, University of Science and Technology of Fujairah, UAE
2 Department of Periodontics, University of Science and Technology of Fujairah, UAE
3 Department of Prosthodontics, University of Science and Technology of Fujairah, UAE
4 Department of Oral Medicine and Radiology, University of Science and Technology of Fujairah, UAE

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Date of Submission24-Apr-2019
Date of Decision23-May-2019
Date of Acceptance28-Oct-2020
Date of Web Publication22-Mar-2021


Aims and Objectives: The aim of this study was to assess the mean overjet in school-going Libyan children and to examine the relationship between increased overjet and permanent incisor's trauma. Materials and Methods: This study is a part of a cross-sectional investigation of aspects of dental health of 2015 school going Libyan children aged between 6 and 16 years old of both genders from both rural and urban areas. Overjet was measured as the horizontal distance in millimetres between the upper and lower incisors. Trauma to permanent incisors was assessed according to Elli's Classification. Results: SPSS version 20.0 for percentages was used for statistical analysis. The relationship between increased overjet and incisor trauma was tested using the Chi-square test at 0.05 significance level. The overjet measurement ranged from -2 mm to 8 mm with the mean overjet of 3.062 (1.23, SD). The prevalence of incisor trauma was statistically significantly higher in children with increased overjet (P < 0.0001). Conclusion: The average mean overjet value in Libyan children is between 2 mm and 3 mm and below or above these values, considered decreased or increased, respectively. Traumatic injuries to permanent incisors significantly increased with increased overjet.

Keywords: Libyan children, overjet, permanent incisors, trauma

How to cite this article:
O. Ergieg SM, Sudhir VR, Shibu TO, Fanas SA, Ashok M. The mean overjet in libyan children and the relationship between increased overjet and incisors trauma. Indian J Dent Res 2020;31:967-70

How to cite this URL:
O. Ergieg SM, Sudhir VR, Shibu TO, Fanas SA, Ashok M. The mean overjet in libyan children and the relationship between increased overjet and incisors trauma. Indian J Dent Res [serial online] 2020 [cited 2022 Jan 25];31:967-70. Available from:

   Introduction Top

Traumatic dental injuries are one of the commonly encountered dental emergencies. Missing anterior teeth in children due to an injury can be a source of considerable physical and psychological discomfort for the child. These consequences also have a significant impact on parents, who are generally concerned with aesthetic and economic aspects of this problem. It varies from a small crack in the enamel to a complete loss of the tooth. Injury to children teeth can be both painful and traumatic to the children. Traumatic injuries to anterior teeth have reported by several investigators.[1],[2],[3],[4] In Asia and Africa, the prevalence of Traumatic dental injury (TDI) to anterior teeth among adolescents ranges from 4% to 35% and 15% to 21%, respectively. In America and Europe, the prevalence varied from 15% to 23% and 23% to 35%, respectively.[5] A total of 50% of school children have sustained traumatic injuries before graduation.[6] Contributing factors make children susceptible to injuries have been widely investigated. These factors included Class-II, div. 1 malocclusion,[3],[7],[8] increased overjet.[8],[9],[10],[11],[12],[13],[14] 71% to 92% of all injuries sustained in a lifetime occurs before the age of 19 years, which occur at home, followed by schools and public places.[15]

The aim of this study is to assess the mean overjet value in Libyan school children and to examine the relationship between increased overjet and trauma to permanent incisors.

   Materials and Method Top

This study is part of a cross-sectional investigation of aspects of dental health in 2015 rural and urban Libyan school children. The research protocol was assessed by the Institutional ethical committee and Review Board, Faculty of Dentistry, University of Benghazi, Libya (Ref: 6/24/17). Registered in as NCT03751189. It follows (STROBE) strengthening the reporting of observational studies in epidemiological guidelines as well as the Helsinki Declaration of Human research, as revised in 2013. The total of 2015 Libyan school children aged 7 to 16 years, almost of equal number of both sexes from each age group from urban (Tobruk) and rural (Kufra) areas were examined in the main study [Table 1].
Table 1: Distribution of the study sample

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Inclusion criteria

  1. Libyan children.
  2. The permanent incisors are present and sufficiently erupted.

Exclusion criteria

  1. Non-Libyan children.
  2. The permanent incisors are absent, or insufficiently erupted.

Reproducibility of the clinical examination

One investigator carries out the study. In order to ensure that the clinical result can be interpreted with reasonable degree of confidence, duplicate assessment was made for 108 children (approximately 5% of the total sample). The paired t-test was used to determine the mean difference between the two sets of assessment. The result showed no statistically significant difference between the two measurements (p < 0.33). This indicates that the examiner managed to ascertain an acceptable level of consistency between initial and repeated examinations.


Overjet was assessed on 1,868 children (the remaining 147 children were excluded because of the concerned teeth were absent or insufficiently erupted), as the horizontal distance in millimetres between the upper and lower incisors. The assessment was made when the teeth are in natural occlusion, using an orthodontic gauge scaled in millimetres. If the measurement fell between the marks of the gauge, then the lower mark was recorded. The measurements for both right and left incisors were carried out.

Trauma to permanent incisors

The total of 1935 children was examined for the incisor trauma. The remaining 80 children were excluded because they did not meet the inclusion criteria. Each child was examined for incisors trauma. The injured tooth or teeth were identified and scored according to the following categories

A Fracture involving enamel.

A fracture involving enamel and dentin.

A fracture involving, enamel, dentin, and pulp.


Non-vital tooth, with or without loss of crown structure.

Tooth lost because of trauma.

   Results Top

Statistical tests

Data entered into SPSS version 20.0 for percentages. The relationship between increased overjet and incisor trauma was tested using the Chi-square test at the 0.05 significance level.


[Table 2] shows the distribution of overjet measurements. It can be seen from this table that overjet measurement ranged from -2 mm to 8 mm with the mean overjet of 3.062 (1.23, standard deviation).
Table 2: Distribution of overjet measurement

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[Table 3] shows the frequency distribution, percentage frequency distribution, the mean overjet value, as well as its standard deviation.
Table 3: The percentage and cumulative frequency distribution of overjet values

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Plotting frequency distribution showed that the value of overjet at 25 percent quartile is 1.8 mm and at 75 percent quartile 3.1 mm. Considering that the biological norm is the value between the first and the third quarter and that in practical and clinical terms, the measurement of overjet value in a fraction of millimetre cannot be done with accuracy. Therefore, the range of biological normal value can be considered between 2.0 mm and 3.0 mm. [Table 2] shows that the overall 69% of children had an overjet of 2-3 mm.

Incisor trauma

[Table 4] shows the prevalence of the incisor trauma among the examined children. It can be seen from this table that 3.6% of the total children included in the study had suffered incisor trauma of which 4.5% boys and 2.7% girls. [Table 5] shows the severity of the trauma to the permanent incisors.
Table 4: The percentage of children with traumatic injuries

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Table 5: Prevalence of different types of injuries

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Incisor trauma and overjet

The relationship between incisor trauma and increased overjet of more than 3 mm was tested using Chi-square test. The result [Table 6] showed that the prevalence of incisor trauma was statistically significantly higher in children with increased overjet (P < 0.0001).
Table 6: Incisor trauma and overjet measurements

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   Discussion Top

In orthodontic diagnosis, overjet is a very important variable, which strongly influences both the need for orthodontic treatment and the type of treatment required. This essential role of overjet has been recognized by most investigators studying the state of occlusion in epidemiological studies and among clinicians.[16],[17],[18],[19],[20] At the present time, there appears to be no documented data regarding the normal range of overjet values in Libyan children. In this study the assessment of overjet was, therefore, considered, to establish what might be considered as a biologically normal range of incisor overjet values. In this study, the overjet value ranged from -2 mm to 8 mm, the mean value was 3.06 mm (with 1.23 SD). It was also found that the overjet values in the mid-quartile range (from 25 to 75 percent quartile) were those between 1.8 and 3.1 mm. In practice, measurement of overjet values in the fraction of millimetre cannot be made with accuracy and hence, in practical terms, the range of these values can be taken between 2 mm and 3 mm. Those parameters may be accepted as normal biological values for this sample within this range. It can be seen that for practical purposes, an increased overjet value would be defined as one exceeding 3 mm. Conversely, a reduced overjet may be diagnosed if the overjet value is less than 2 mm. Compared to other studies that has used similar methods, the mean overjet for English children was 3.4 mm[18] and for Nigerian children, it was 2.8 mm.[12] It could be suggested therefore that, Libyan children have a mean overjet value which is a little less than in in English children and slightly larger than in Nigerian children. It could be that the mean overjet value in Libyan children which was low compared to that of Caucasian and slightly higher than that seen in Negroid children. This may be because the present sample consisted of mixed white and black children. From the cephalometric study of Swedish children, it was found that the mean overjet of is 3.8 mm,[21] slightly higher than the finding of this study. In Iraqi children, the mean overjet was 3.4 mm,[22] slightly closer to the mean overjet value for Libyan children.

Trauma to permanent incisors is a perplexing problem to the child, parents, and the dentist. The overall prevalence of children with traumatized incisors (3.6%), which was considerably lower than those reported by other investigators in different child population[1],[5],[23],[24] with the exception of Iraq children,[25] which showed lower prevalence (2.8%) than that reported in this study. The factors, which might have contributed to this low frequency of incisor trauma, that the vigorous contact sports, such as American football, rugby, ice hockey were not common sports among Libyan children. Other factors include the playground have soft bases, and lip coverage and lip adequacy which requires further investigation.

The relation between incisor trauma and increased overjet (4 mm or more) was examined. The difference was statistically significant (P < 0.0001), which suggested that children with increased overjet are at risk of injuring their incisor teeth. This result supports the view of previous workers in a different population, that protruded incisors are more likely to be injured.[3],[8],[9],[13],[23],[25],[26],[27],[28] Other study found on association.[29],[30],[31],[32],[33],[34] The result of this study also indicates the needs for preventive strategies to deal with protruding incisors to reduce the incidence of dental trauma in Libyan school children.

Finally, traumatic dental injuries to the teeth of children presents a very complex interaction between their oral condition and their behaviour. Therefore, the prevention of traumatic injuries to children's teeth should be considered as a priority. It should include oral pre-disposing factors, environmental determinant, and human behaviour, which make children more vulnerable to dental trauma.

   Conclusions Top

Overall, the mean overjet values in Libyan school children is ranging between 2.0 and 3.0 mm. The frequency of incisor trauma was very low. The incidence of incisor trauma was statistically significantly higher in children with increased overjet.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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Correspondence Address:
Dr. Suleiman M O. Ergieg
Department of Pediatric Dentistry, University of Science and Technology of Fujairah
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_361_19

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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