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Accuracy of linear smartphone measurements compared to a digital single lens reflex camera Cover

Accuracy of linear smartphone measurements compared to a digital single lens reflex camera

Australasian Orthodontic Journal
Volume 41 (2025): Issue 1 (January 2025)
By:
Open Access
|Jul 2025

Figures & Tables

Figure 1.

Extraoral photograph with ruler.
Extraoral photograph with ruler.

Figure 2.

Intraoral photograph with ruler.
Intraoral photograph with ruler.

Figure 3.

Example of the visual comparison of the extraoral photographs. The photographs were superimposed over the nose and left eye. The shadow of the larger image was from the DSLR photograph.
Example of the visual comparison of the extraoral photographs. The photographs were superimposed over the nose and left eye. The shadow of the larger image was from the DSLR photograph.

Figure 4.

Example of the visual comparison of the intraoral photographs. The vertical lines represent the upper incisor widths in the photographs taken with the DSLR camera (top) as the gold standard.
Example of the visual comparison of the intraoral photographs. The vertical lines represent the upper incisor widths in the photographs taken with the DSLR camera (top) as the gold standard.

Figure 5.

Illustration of barrel distortion in smartphone photography compared to a DSLR camera.
Illustration of barrel distortion in smartphone photography compared to a DSLR camera.

Data analysis of the studied variables for extraoral measurements obtained from photographs on two separate occasions

ParameterDeviceICC testPaired t-test
ICCp-valueMean difference in mm (SD)Standard error mean95% CI of differencet-stat (df)p-value
ZA-ZADSLR1.000<0.001-0.10 (0.31)0.06(-0.22, 0.02)-1.75 (29)0.090
Xiaomi0.990<0.001-0.53 (1.49)0.27(-1.08, 0.03)-1.93 (29)0.106*
Or-OrDSLR0.997<0.001-0.14 (0.37)0.07(-0.27, 0.00)-1.99 (29)0.056
Xiaomi0.987<0.001-0.11 (0.70)0.13(-0.37, 0.15)-0.85 (29)0.400
Ac-AcDSLR0.989<0.001-0.12 (0.61)0.11(-0.35, 0.11)-1.08 (29)0.382*
Xiaomi0.988<0.001-0.07 (0.60)0.11(-0.29, 0.16)-0.62 (29)0.538
Tr-MeDSLR0.999<0.001-0.22 (0.74)0.13(-0.49, 0.06)-1.63 (29)0.114
Xiaomi0.993<0.001-0.58 (1.64)0.30(-1.19, 0.03)-1.94 (29)0.062
Sn-MeDSLR0.995<0.001-0.09 (0.59)0.11(-0.31, 0.13)-0.85 (29)0.401
Xiaomi0.992<0.001-0.22 (0.72)0.13(-0.49, 0.05)-1.70 (29)0.101

Comparison of intraoral measurements using DSLR and smartphone

ParameterPaired t-testp-value
Mean difference in mm (SD)Standard error mean95% CI of differencet-stat (df)
Incisor width0.22 (0.34)0.06(0.09, 0.35)3.54 (29)0.001
Canine width0.31 (0.42)0.08(0.15, 0.46)3.96 (29)<0.001
Incisor height0.31 (0.47)0.09(0.14, 0.49)3.69 (29)0.001
Canine height0.26 (0.39)0.07(0.11, 0.41)3.58 (29)0.001

Data analysis of the studied variables for intraoral measurements obtained from photographs on two separate occasions

ParameterICC testPaired t-test
DeviceICCp-valueMean difference in mm (SD)Standard error mean95% CI of differencet-stat (df)p-value
Incisor widthDSLR0.971<0.001-0.01 (0.23)0.04(-0.09, 0.08)-0.15 (29)0.884
Xiaomi0.955<0.0010.05 (0.34)0.06(-0.08, 0.18)0.79 (29)0.437
Canine widthDSLR0.977<0.001-0.09 (0.25)0.05(-0.18, 0.01)-1.92 (29)0.064
Xiaomi0.957<0.0010.10 (0.31)0.06(-0.02, 0.21)1.68 (29)0.105
Incisor heightDSLR0.892<0.001-0.06 (0.27)0.05(-0.16, 0.05)-1.13 (29)0.269
Xiaomi0.956<0.0010.06 (0.17)0.03(-0.01, 0.12)1.77 (29)0.087
Canine heightDSLR0.971<0.0010.06 (0.19)0.03(-0.01, 0.13)1.79 (29)0.084
Xiaomi0.957<0.0010.00 (0.23)0.04(-0.09, 0.08)-0.04 (29)0.969

Mean and standard deviation of extraoral and intraoral measurements

ParameterDeviceMean (mm)SD
ZA-ZADSLR143.5911.36
Xiaomi137.3010.26
Or-OrDSLR66.034.60
Xiaomi63.834.26
Ac-AcDSLR40.973.93
Xiaomi39.753.88
Tr-MeDSLR182.8513.57
Xiaomi178.4814.01
Sn-MeDSLR68.835.85
Xiaomi65.455.23
Incisor widthDSLR8.040.59
Xiaomi7.810.58
Canine widthDSLR4.760.79
Xiaomi4.450.78
Incisor heightDSLR9.520.99
Xiaomi9.201.01
Canine heightDSLR8.501.16
Xiaomi8.241.04

Comparison of extraoral measurements using DSLR and smartphone

ParameterPaired t-testp-value
Mean difference in mm (SD)Standard error mean95% CI of differencet-stat (df)
ZA-ZA6.29 (3.24)0.59(5.08, 7.50)10.62 (29)<0.001
Or-Or2.20 (1.28)0.23(1.72, 2.68)9.40 (29)<0.001
Ac-Ac1.22 (1.36)0.25(0.71, 1.73)4.91 (29)<0.001
Tr-Me4.37 (4.54)0.83(2.68, 6.07)5.28 (29)<0.001
Sn-Me3.38 (2.42)0.44(2.48, 4.29)7.65 (29)<0.001

Smartphone/DSLR ratio analysis

ParameterMean Ratio (M ± SD)t (df = 29)p-valueMean Difference95% CI of Difference
ZA-ZA0.9568 ± 0.0218-10.856<0.001-0.0432[-0.0513, -0.0351]
Or-Or0.9670 ± 0.0185-9.777<0.001-0.0330[-0.0399, -0.0261]
Ac-Ac0.9705 ± 0.0311-5.190<0.001-0.0295[-0.0411, -0.0179]
Tr-Me0.9760 ± 0.0246-5.334<0.001-0.0240[-0.0332, -0.0148]
Sn-Me0.9518 ± 0.0340-7.768<0.001-0.0482[-0.0608, -0.0355]
Incisal Width0.9733 ± 0.0418-3.5050.002-0.0267[-0.0423, -0.0111]
Canine Width0.9379 ± 0.0906-3.755<0.001-0.0621[-0.0959, -0.0283]
Incisal Height0.9675 ± 0.0480-3.713<0.001-0.0325[-0.0505, -0.0146]
Canine Height0.9722 ± 0.0452-3.3680.002-0.0278[-0.0447, -0.0109]
DOI: https://doi.org/10.2478/aoj-2025-0024 | Journal eISSN: 2207-7480 | Journal ISSN: 2207-7472
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Language: English
Page range: 246 - 255
Submitted on: Feb 1, 2025
Accepted on: Jun 1, 2025
Published on: Jul 1, 2025
Published by: Australian Society of Orthodontists Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 times per year
Related subjects:
Medicine,
Basic medical science,
Basic medical science, other

© 2025 Nor Nadia Zakaria, Shen Lun Ng, Yu Ning Teng, Afiqah Abdul Aziz, published by Australian Society of Orthodontists Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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