Global Dental Arch Dimension Norms and Sexual Disparities : An overview

Background: The aim of the present study was to do an overview of the arch dimension for various populations. Also, to evaluate the various type of measurement methods and sexual disparities. Two reviewers independently performed the selection process and the quality of studies was assessed. Method: Studies published form January 2000 until October 2015 were identified in electronic databases: Pubmed, Scopus, Science direct, Web of Science, Medpilot and Medline using keywords.Criteria used included: observational studies, Arch size measured, Permanent dentition, Arch dimension investigated via plaster and digital dental models, measurement via calipers and computers software’s. Result: The forest plots showed the continuous trend for the greater arch dimension for male in relation to female. The current overview showed the arch dimension and its disparities for various populations. Conclusion: The various methods to assess arch dimension should be carefully considered and well conducted as part of the clinical assessment of orthodontic treatment, since arch dimension could influence the diagnosis and treatment planning of orthodontist.


Introduction
Malocclusion is a communal quandary in all inhabitants. 1Although the nature of malocclusion varies in different population, but teeth size and arch length inconsistency are considered to be an important etiological factors. 2 The arch dimension is of preponderant importance in the various dental specialties such as Orthodontics, Prosthodontics, Forensic Dentistry and Dental Anthropology.Nature has given an ideal balance between the maxillary and mandibular teeth size that should be attained for the ideal occlusion and aesthetics, especially in relation to the finishing phase in orthodontics. 3,4,5There is obvious population variation in the pattern and magnitude of sexual dimorphism. 6,7,8Teeth in relation to sexual dimorphism have been of prodigious importance to anthropologists and forensic odontologists as well as the focus of many studies for gender assessment. 9,10onventional caliper was used by researchers to investigate tooth dimension, to identify the sexual disparities through mesiodistal, 11,5,12,13 buccolingual 10,11,12,13 and diagonal crown 14 diameters of teeth.Geomorphometrics is the quantitative approach that refers to the morphology of an entity depends on landmarks.This technique resolves numerous problems accompanying with out-of-date methods of measurements. 15The current overview showed the arch dimension and its disparities for various populations.The various methods to assess arch dimension should be carefully considered and well conducted as part of the clinical assessment of orthodontic treatment, since arch dimension could influence the diagnosis and treatment planning of orthodontist.

Material and Methods
Two reviewers independently performed the selection process and the quality of studies was assessed.Studies published form January 2000 until October 2015 was identified in electronic databases: Table 1 show the Sought electronic databanks sources and Key word words used in data base search.Criteria used included: observational studies, Arch size measured, Permanent dentition, Arch dimension investigated via plaster and digital dental models, measurement via calipers and computers software's.

Discussion
During the mixed dentition, prediction of the mesiodistal dimensions of unerupted permanent teeth is of great importance in diagnosis and treatment planning.Correct assessment of the size of the unerupted tooth allows improved treatment plan to deal with tooth size/arch length discrepancies. [16]or mixed dentition tooth size and arch dimension analysis direct measurement methods including hand-held calipers, graphs and scale to record dimensions and tooth size on dental casts have been used. 17.18]These digital model studies provide more accurate and reliable tools for obtaining measurements and carrying out dental analysis. 19,20Moreover, they have additional benefits, such as accessibility of the images produced, reduction in storage costs and the ability to analyze images by using sophisticated software's. 19,21n orthodontic treatment the arch form and shape are usually modified to achieve the treatment goals by the various forms of wires used in the treatment course.The patient's existing arch form appears to be the best guide for the stability of the arch form after treatment. 1he arch size and shape are of scrupulous importance in dentistry.Thus a diversity of diagnostic and analytical indices had been anticipated to help and forecast dental arch development and help out through treatment planning. 22For the relieving of crowding and adjustment of arch length, the dental arch expansion is one of the methods to solve the problem by non-extraction orthodontic treatment.

Conclusion
In conclusion, the dental arch dimension has been measured by various hand held and digital models.All the methods showed the sexual disparities in the dental arch dimension.Arch dimension investigated via plaster and digital dental models, measurement via calipers and computers software's.The current overview showed the arch dimension and its disparities for various populations.Therefore, various methods to assess arch dimension should be carefully considered and well conducted as part of the clinical assessment of orthodontic treatment, since arch dimension could influence the diagnosis and treatment planning of orthodontist.

Figure 1 ,
2,3,4,5 and 6 1,25-35 show the arch dimension width for Inter canine, Inter premolar, Inter molar of maxillary and mandibular arch respectively.Arch dimension has greater values for males in relation to females.The Forest plots show the continuous trend of under prediction of female arch width.

Table 1 . Sought electronic databanks sources and Key word words used in data base search Sought electronic databanks Key word words
Ethical approval: This study was approved by local Ethics Committee prior the submission for publication.Results Conflict of interest: The authors declared no conflict of interest Authors' contributions: Data gathering and idea owner of this study: Rafiqul Islam Study design: Rafiqul Islam, Mohammad Khursheed Alam Data gathering: Mohammad Khursheed Alam, Fazal Shahid Writing and submitting manuscript: Rafiqul Islam, Mohammad Khursheed Alam Editing and approval of final draft: Fazal Shahid , Mohd Fadhli Khamis