Saudi Journal of Oral Sciences

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 3  |  Issue : 2  |  Page : 69--74

Cephalometric norms of skeletal relationship among populations in selected Arab countries: A systematic review and meta-analysis


Deema Ali Alshammery1, Sarah Almubarak2, Alhanouf Bin Hezaim2, Razan Alkhunein2, Sharat Chandra Pani3, Hezekiah Mossadomi4,  
1 Department of Orthodontics, Riyadh Colleges of Dentistry and Pharmacy, Riyadh, Saudi Arabia
2 Dental Intern, Riyadh Colleges of Dentistry and Pharmacy, Riyadh, Saudi Arabia
3 Department of Preventive Dental Sciences, Riyadh Colleges of Dentistry and Pharmacy, Riyadh, Saudi Arabia
4 Department of Oral and Maxillofacial, Riyadh Colleges of Dentistry and Pharmacy, Riyadh, Saudi Arabia

Correspondence Address:
Deema Ali Alshammery
Department of Orthodontics, Riyadh Colleges of Dentistry and Pharmacy, P. O. Box: 84891, Riyadh 11681
Saudi Arabia

Abstract

Background and Aim: Despite the availability of several published studies on cephalometric norms among different Arabic countries, “Caucasian” norms are still used as the standard in these countries. The aim of this study was to review the existing literature on the topic and show a meta-analysis of the review for the skeletal values observed in the study. Materials and Methods: An electronic search was conducted for studies that examined the SNA, SNB, and ANB angles in study subjects in different Arabic speaking countries. A total of 16 studies were eligible for inclusion in the systematic review and a meta-analysis with results from these studies was completed using the OpenMeta-Analyst software (Brown University, Providence, RI, USA). The weighted mean and I2 for heterogeneity were computed individually for the SNA, SNB, and ANB angles, respectively. Results: The result of the meta-analysis showed a significant heterogeneity for the SNA, SNB, and ANB angles of each of the populations, suggesting that the populations of the different Arab nations studied were ethnically diverse. Conclusion: Within the limitations of this study, it was concluded that given the high level of heterogeneity it may not be feasible to speak of the different Arabic speaking nations as a distinct population for the purpose of developing norms for cephalometric skeletal relationships.



How to cite this article:
Alshammery DA, Almubarak S, Hezaim AB, Alkhunein R, Pani SC, Mossadomi H. Cephalometric norms of skeletal relationship among populations in selected Arab countries: A systematic review and meta-analysis.Saudi J Oral Sci 2016;3:69-74


How to cite this URL:
Alshammery DA, Almubarak S, Hezaim AB, Alkhunein R, Pani SC, Mossadomi H. Cephalometric norms of skeletal relationship among populations in selected Arab countries: A systematic review and meta-analysis. Saudi J Oral Sci [serial online] 2016 [cited 2019 Sep 22 ];3:69-74
Available from: http://www.saudijos.org/text.asp?2016/3/2/69/188079


Full Text

 Introduction



The lateral cephalometric radiographs are a two-dimensional image that illustrates hard and soft tissues to be used as a tool in orthodontics diagnosis and treatment planning. Cephalometric standard values are a well-accepted practical guideline in orthodontic diagnosis and treatment planning.[1]

Several studies have been carried out to determine craniofacial norms of different populations in the Arabic-speaking countries.[2],[3],[4],[5],[6],[7],[8],[9] Regardless of the availability of multiple published studies on cephalometric norms in different Arab countries, there is no evidence of published standards for these countries. Furthermore, there is a lack of consensus on what exactly constitutes an “Arabic population” with authors agreeing that the population of Arabic countries is often an ethnically diverse composite of several races.[8],[9]

A meta-analysis is defined as a review that uses quantitative methods to consolidate the statistical results from more than one studies and create a mean for the accuracy of the diagnostic test to approach a standard conclusion.[10] A meta-analysis not only gives the mean value for a particular reading but also gives the reader an estimate of the acceptability of the mean to each study included in the analysis.[10] It is for this reason that a meta-analysis can serve as a useful tool in establishing if the statistical means incorporated into an analysis should belong to a single population (homogenous) or different populations (heterogeneous). Despite this apparently obvious benefit, there are few meta-analyses that have attempted to combine cephalometric values into a meta-analysis.[6]

Of the different cephalometric values used, one of the most accepted measures of maxilla-mandibular relationship is the relationship between the sella turcica (S), nasion (N), and the deepest point of the maxillary (A) and mandibular (B) alveolar processes. The aim of this study was to review the existing literature on the SNA and SNB angles in different Arabic-speaking populations and subject the results to a meta-analysis. The results of the meta-analysis were also used to determine adequate homogeneity or lack of it in the reviewed studies and to consider the inhabitants of Arabic speaking countries as a homogenous “Arabic Population.”

 Materials and Methods



Electronic database, PubMed, Saudi Digital Library, and Google Scholar were searched from January 1966 to December 2015 among 22 Arabic countries, namely Saudi Arabia, Kuwait, UAE, Bahrain, Qatar, Oman, Yemen, Egypt, Morocco, Algeria, Sudan, Somalia, Lebanon, Jordan, Palestine, Tunisia, Libya, Mauritania, Djibouti, Iraq, Syria, and Comoros Island using the key words Arab, Arabic, and cephalometric. The Population, Investigation, Cohort, and Outcome or PICO criteria were used for the selection of the studies.

Population was defined as studies that were conducted in the Middle East and North Africa region. The current meta-analysis was defined as cohort studies done on individuals aged between 16 and 45 years of age.

Investigation

Only studies using lateral cephalograms of patients without malocclusion were included in the study.

Comparator

The adjusted mean SNA and SNB angles of the studies were used as the comparator for homogeneity of the population.

Outcome

The SNA, SNB, and ANB angles were the outcomes included in the meta-analysis. The PRISMA flow chart of the methodology used in the study is presented in [Figure 1].{Figure 1}

The articles included in the qualitative synthesis were then used as the basis for the meta-analysis. The number of participants, mean and standard deviation for the SNA, SNB, and ANB of each of the articles were entered into the OpenMeta-Analyst (Brown University, Providence, RI, USA). Random effects models were generated for the SNA, SNB, and ANB from each study.

Forest plots were generated to graphically depict the distribution of the population, while the I2 value was used as an indicator of heterogeneity of the population.

 Results



The online search yielded a total of 122 articles that were related to the topic on initial examination. Of the abstracts, a total of 54 articles were screened for eligibility, while 68 articles were found to be unrelated to the present topic [Figure 1]. Of the 54 articles, a total of 38 articles were found to be unrelated to the topic. Of the 38 full texts that were analyzed, 22 articles had to be excluded as they did not meet the inclusion criteria [Table 1]. A total of 16 articles were used in the formulation of the final qualitative synthesis and the meta-analysis [Table 2].{Table 1}{Table 2}

The analysis for the SNA angle revealed that there was a significant heterogeneity in the population (I2 = 91.71%, P < 0.001). Although the weighted mean was 81.92° (confidence interval [CI] 81.2–82.6), the means ranged from 76.7° to 83.3° [Figure 2]. For the SNB angle, the analysis revealed an even greater heterogeneity (I2 = 98.1%, P < 0.001). The weighted mean SNB angle was 78.96° (CI 77.5–80.42) with a range from 69° to 82° [Figure 3]. The adjusted mean ANB angle was 2.89° (CI 2.67–3.10) with a range from 2.50°C to 4.03°C [Figure 4]. The heterogeneity for ANB was lower than for SNA or SNB (I2 = 72.77%, P < 0.001) and there was still significant heterogeneity among the different studies{Figure 2}{Figure 3}{Figure 4}

 Discussion



The Arabic speaking countries extend from the Arabian Peninsula all the way up to the Western parts of North Africa.[6] The terms “Arabic Population” or “Arabs” have often been used to describe the inhabitants of these countries.[6],[16] However, several authors have pointed out that these populations are ethnically diverse and have questioned the rationale of attempting to define an “Arab norm.”[20],[29] The primary aim of this meta-analysis was to test the homogeneity of the populations included in this study.

The SNA, SNB, and ANB have been the gold standards of cephalometric analyses since the concept was introduced by Hofrath and Broadbent independently in the 1930s.[1] It is generally accepted that the SNA angle should be 82° (±4°), while the SNB angle should be 80° (±4°). This leaves an ANB angle (which is usually a derived measurement) of approximately 2.[1],[15],[26] The values seen in most studies in this meta-analysis fell within this range with the adjusted mean being almost the same as the ideal suggested in literature. This is significant as the cephalometric ideals in use today were developed not on the basis of scientific methods but on esthetic perceptions.[1]

Heterogeneity measurements test the variation both within and between the different studies included in a meta-analysis.[44],[45] There are traditionally two methods used to test this concept: The Cochran's Q and the I2.[44] Given that the Cochran's Q can give a falsely high heterogeneity, and the I2 is the preferred measure of heterogeneity for studies that involve population-based data.[45] The significant heterogeneity observed in this study suggests that the variation within each population was too high to consider them as distinct ethnic groups. This is in keeping with the views of the previous studies that have questioned the idea of Arab populations as distinct ethnic entities.[7],[9]

A majority of the studies included in this meta-analysis are from Saudi Arabia.[9],[30],[31],[32],[33],[34],[35] The idea of developing cephalometric norms for the Saudi population has been previously explored, however, the attempts to define a mean value was always accompanied by a large standard deviation.[30],[31],[32],[33],[34],[35] The results of this meta-analysis suggest that the Saudi population (as well as the other Arab populations studied) cannot be viewed as a homogenous ethnic entity.

The results of this meta-analysis must be viewed against a number of limitations. The most significant one being the fact that the studies included in the analysis examined so-called “normal” individuals. This may explain why the average values obtained are so close to the proposed Caucasian ideal values. Furthermore, nearly all the studies found in the literature review had a limited number of participants. Therefore, the data obtained from this meta-analysis must be viewed in conjunction with other studies from these populations that looked at patient preference, as well as ideal cephalometric norms.

 Conclusion



Within the limitation of this study, it could be concluded that the Arab populations examined did not constitute a homogenous ethnic entity. In the light of this study, the idea of unified Arab cephalometric norms must be revisited, reviewed, or rationalized.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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