Dental Arch Dimensions in Saudi Adults
Objective. The aim of this study was to investigate the arch dimensions (width, length, and depth) in Saudi Arabia. Materials and Methods. 169 orthodontic models (73 males and 96 females) made of white stone were selected according to inclusion criteria. Measurement of arch dimensions was taken including width, length, and depth at different reference points. Differences between males and females were tested using independent samples t-test. Results. The sample comprised subjects aged 18–33 years old. Most measurements showed higher values for males compared to females. Saudi males showed smaller intercanine widths compared to Caucasians and Southern Chinese but larger widths in females compared to Caucasians and smaller widths compared to Southern Chinese. Saudi males and females showed larger intermolar widths compared to Caucasians but smaller intermolar widths compared to Southern Chinese. For arch length, Saudis showed longer arches compared to Yemenis for both males and females but smaller palatal depths compared to Yemenis. Conclusions. Differences in intercanine width, intermolar width, and palatal length and depth were found between Saudis and other nationalities. Male and female participants had differences in most of the measurements.
Dental arch dimensions are of special interest for dentists and orthodontists in particular. Changes in the arch width, length, and height can result from orthodontic treatment; hence, an understanding of the dental arch dimensions is crucial [1–5]. Dental arches have been investigated using different measurements and reference points, including but not limited to, intercanine, interpremolar, and intermolar widths, either between cusps or fossae, anterior palatal and mandibular lengths, molar vertical distance, total palatal and mandibular lengths, and palatal depth [6–11].
Ward et al. have reported significant changes in maxillary and mandibular intercanine widths in orthodontically treated group compared to untreated group . In patients treated with Frankel II appliance, significant increases in arch width and arch perimeter were found .
There are many studies that have been conducted to investigate the dental arch dimensions and relationships in different ethnicities and different geographical areas [14–20]. Few studies have been conducted to investigate arch dimensions in Saudi population [21, 22]. Therefore, the aim of this study was to investigate the arch dimensions (width, length, and depth) in Saudi adults.
2. Materials and Methods
This study was registered at the research center at Riyadh Colleges of Dentistry and Pharmacy with registration number: FRP/2014/73 and IRB approval was obtained. Inclusion criteria were as follows:(1)Saudi subjects over 18 years of age(2)Class I canine and molar relationships(3)Presence of all permanent teeth up to the second molars(4)No previous orthodontic treatment or facial surgeries(5)No more than mild crowding or spacing (<3 mm)(6)No history of parafunctional oral habits(7)No large restorations or crowns(8)No tooth anomalies
Orthodontic models (n = 169; 73 males and 96 females) made of white stone in the orthodontic clinics were examined; those that satisfied the inclusion criteria were selected. Measurements of arch dimensions of the maxilla and mandible (width, length, and depth) were taken as described by Ling and Wong  and Al-Zubair . Definitions and illustrations of all variables are shown in Figures 1–4 and Table 1. Two examiners took the measurements using a digital sliding caliper (Carrera Precision CP9806-TF, Max Tool LLC, Calif., USA).
3. Method Error
For the purpose of calibration, the two examiners took all the measurements on 20 dental models and then their measurements were compared.
3.1. Statistical Analysis
Independent sample t-test was used to determine any statistically significant differences between males and females for each measurement. Interclass correlation coefficient was used to determine interexaminer reliability. SPSS software was used for the statistical analysis (IBM SPSS Statistics for Mac, Version 24.0, IBM Corp., Armonk, NY).
The sample consisted of 169 individuals (male: n = 73, aged 23.9 years ± 4.5; female: n = 96, aged 23.8 years ± 4.3). All results are shown in Tables 2–5. All maxillary and mandibular measurements showed statistically significant greater values for males compared to females (t-test; ) except for U7ML, U4CB, U3CL, U3CB, U3MC, U2MC, L5CL, L5CG, L4CC, L4CB, L2MC, APL, PL, TPL, AML, ML, and PD (t-test; ). Interexaminer reliability was high, ranging from 0.88 to 0.92 ().
In the present study, an effort was made to establish normal values for some parameters that have never been studied in Saudi. We chose to conduct measurements using many reference points described in the literature to allow for comparison with other populations’ measurements [9, 11].
Comparison of intercanine widths among different populations showed small differences in Saudis between the present study and other studies and close measurements compared to Caucasians [20–22], while Southern Chinese showed the largest arch widths in the canine area (Table 6) .
Comparisons of the arch widths at the first molar showed a difference of about 1 mm between Saudis in our studies and Saudis in other studies. Southern Chinese were found to have the largest arch width followed by Saudis and then by Caucasians [9, 20] (Tables 7 and 8).
The measurements established in the present study can serve as a database to which, orthodontic treatment of Saudi adults can be planned. Limitations of this study include a relatively small sample and that the study was confined to Riyadh City.
(i)This study serves the purpose of establishing a database for arch dimensions for Saudi adult population.(ii)Comparisons between Saudis and other populations showed differences in intercanine width, intermolar width, and palatal length and depth.(iii)Males and females showed statistically significant differences in most of the measurements where males had larger measured values.
Conflicts of Interest
The authors declare that there are no conflicts of interest regarding the publication of this paper.
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