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Mandibular buccal shelf asymmetry and bone density in vietnamese adults: a CBCT study Cover

Mandibular buccal shelf asymmetry and bone density in vietnamese adults: a CBCT study

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

Figures & Tables

Figure 1.

CBCT sagittal view of dTB asymmetry in a single patient. Sagittal slice comparing left and right total bone thickness (dTB) at R6X (distal root of the mandibular first molar, FDI 36D, 46D) in Class I bimaxillary protrusion. Measurements are taken at 6 mm, 9 mm, and 12 mm below the cementoenamel junction (CEJ). Left side: 4.27 mm (6 mm), 5.91 mm (9 mm), 6.56 mm (12 mm). Right side: 5.14 mm (6 mm), 7.40 mm (9 mm), 8.44 mm (12 mm).
CBCT sagittal view of dTB asymmetry in a single patient. Sagittal slice comparing left and right total bone thickness (dTB) at R6X (distal root of the mandibular first molar, FDI 36D, 46D) in Class I bimaxillary protrusion. Measurements are taken at 6 mm, 9 mm, and 12 mm below the cementoenamel junction (CEJ). Left side: 4.27 mm (6 mm), 5.91 mm (9 mm), 6.56 mm (12 mm). Right side: 5.14 mm (6 mm), 7.40 mm (9 mm), 8.44 mm (12 mm).

Figure 2.

Correlation plot of dTB and MĐV at R7X 12 mm. Scatter plot showing no significant correlation (Spearman’s r=–0.087 P=0.646; R2=0.002) between total bone thickness (dTB) at 12 mm below CEJ at the distal root of the mandibular second molar (R7X, FDI 37D, 47D) and cortical bone density (MĐV) averaged across 3°, 45°, and 60° angulations in Class I bimaxillary protrusion patients. The x-axis represents dTB (mm), ranging from 4.00 to 14.00 mm, and the y-axis represents MĐV (Hounsfield Units, HU), ranging from 800.00 to 1200.00 HU. Data represent 30 patients.
Correlation plot of dTB and MĐV at R7X 12 mm. Scatter plot showing no significant correlation (Spearman’s r=–0.087 P=0.646; R2=0.002) between total bone thickness (dTB) at 12 mm below CEJ at the distal root of the mandibular second molar (R7X, FDI 37D, 47D) and cortical bone density (MĐV) averaged across 3°, 45°, and 60° angulations in Class I bimaxillary protrusion patients. The x-axis represents dTB (mm), ranging from 4.00 to 14.00 mm, and the y-axis represents MĐV (Hounsfield Units, HU), ranging from 800.00 to 1200.00 HU. Data represent 30 patients.

Figure 3.

Heat map of total bone thickness (dTB) at sites R6G, R6X, R7G, and R7X at 6 mm, 9 mm, and 12 mm below the cementoenamel junction (CEJ) in Class I bimaxillary protrusion and Class III patients. The colours represent bone thickness (mm), ranging from yellow (thin) to red (thick). (A) Class I shows pronounced left-right asymmetry at R6G and R6X. (B) Class III displays uniform thickness bilaterally. Data represent 30 patients per group.
Heat map of total bone thickness (dTB) at sites R6G, R6X, R7G, and R7X at 6 mm, 9 mm, and 12 mm below the cementoenamel junction (CEJ) in Class I bimaxillary protrusion and Class III patients. The colours represent bone thickness (mm), ranging from yellow (thin) to red (thick). (A) Class I shows pronounced left-right asymmetry at R6G and R6X. (B) Class III displays uniform thickness bilaterally. Data represent 30 patients per group.

Intergroup dTB Comparison below CEJ Levels (mm)

SiteLevelClass I BPClass IIIP (I vs III)
R6G6 mmMean±SD: 1.91±1.02 Median (IQR): 1.47 (1.28–2.35)Mean±SD: 1.77±0.90 Median (IQR): 1.58 (1.15–2.14)0.652
R6G9 mmMean±SD: 2.51±1.25 Median (IQR): 2.17 (1.80–3.13)Mean±SD: 2.57±1.21 Median (IQR): 2.32 (1.82–3.18)0.695
R6G12 mmMean±SD: 3.17±1.41 Median (IQR): 2.94 (2.34–3.76)Mean±SD: 3.59±1.48 Median (IQR): 3.37 (2.66–4.47)0.196
R6X6 mmMean±SD: 2.43±1.19 Median (IQR): 2.17 (1.61-2.90)Mean±SD: 2.22±0.93 Median (IQR): 2.13 (1.55-2.62)0.652
R6X9 mmMean±SD: 3.56±1.47 Median (IQR): 3.38 (2.73-4.32)Mean±SD: 3.41±1.27 Median (IQR): 3.29 (2.72–3.85)0.554
R6X12 mmMean±SD: 4.44±1.60 Median (IQR): 4.46 (3.68-5.28)Mean±SD: 4.56±1.52 Median (IQR): 4.63 (3.63-5.20)0.756
R7G6 mmMean±SD: 4.78±1.77 Median (IQR): 4.83 (3.57-5.74)Mean±SD: 4.29±2.31 Median (IQR): 3.90 (2.75–5.20)0.119
R7G9 mmMean±SD: 6.70±1.79 Median (IQR): 7.02 (5.74-7.76)Mean±SD: 6.22±2.01 Median (IQR): 5.97 (5.12-7.01)0.058
R7G12 mmMean±SD: 8.02±1.81 Median (IQR): 8.36 (6.61-9.21)Mean±SD: 7.59±1.90 Median (IQR): 7.37 (6.65–8.18)0.098
R7X6 mmMean±SD: 6.44±2.00 Median (IQR): 6.50 (5.15-7.33)Mean±SD: 6.05±2.24 Median (IQR): 6.13 (4.43–7.31)0.333
R7X9 mmMean±SD: 7.97±1.86 Median (IQR): 7.96 (7.00-9.16)Mean±SD: 7.76±1.88 Median (IQR): 7.56 (6.52–8.42)0.399
R7X12 mmMean±SD: 8.82±1.83 Median (IQR): 8.86 (7.74-9.85)Mean±SD: 8.68±1.86 Median (IQR): 8.48 (7.74–9.48)0.520

Correlation Between dTB and Density averaged across all angulations below CEJ Levels

SiteLevelClass I BP dTB vs MĐV (r, p)Class I BP dTB vs MĐX (r, p)Class III dTB vs MĐV (r, p)Class III dTB vs MĐX (r, p)
R6G6 mm–0.024, 0.898–0.031, 0.871–0.291, 0.119–0.174, 0.359
R6G9 mm0.057, 0.7660.067, 0.725–0.146, 0.441–0.310, 0.095
R6X9 mm0.169, 0.371–0.056, 0.769–0.167, 0.378–0.253, 0.177
R7X12 mm–0.087, 0.646–0.002, 0.991–0.147, 0.4390.003, 0.986

Left-Right Asymmetry in dTB below CEJ Levels (mm)

SiteLevelClass I BP Left Mean (Median) (IQR)Class I BP Right Mean (Median) (IQR)P (Left vs Right)Class III Left Mean (Median) (IQR)Class III Right Mean (Median) (IQR)P (Left vs Right)
R6G6 mm1.57±0.93 (1.37) (0.95-1.99)2.25±1.38 (1.70) (1.22-3.03)0.004*1.75±1.13 (1.54) (1.07-2.04)1.78±1.00 (1.57) (1.22-2.06)0.376
9 mm2.13±1.27 (1.85) (1.40-2.42)2.90±1.60 (2.63) (1.85-3.53)0.008*2.68±1.68 (2.47) (1.59-3.31)2.46±1.23 (2.24) (1.76-2.98)0.696
12 mm2.77±1.62 (2.53) (1.77-3.46)3.57±1.90 (3.29) (2.24-4.33)0.049*3.78±2.09 (3.58) (2.51-4.52)3.39±1.54 (3.16) (2.35-4.38)0.299
R6X6 mm2.09±1.08 (1.88) (1.57-2.50)2.77±1.51 (2.53) (1.49-3.49)0.002*2.09±1.16 (2.10) (1.12-2.61)2.36±0.97 (2.11) (1.84-2.77)0.180
9 mm3.30±1.46 (3.29) (2.55-3.98)3.82±1.72 (3.57) (2.54-5.16)0.032*3.31±1.58 (3.16) (2.52-3.81)3.52±1.30 (3.77) (2.77-4.16)0.644
12 mm4.19±1.66 (4.15) (3.11-4.96)4.68±1.81 (4.89) (3.58-5.74)0.0634.48±1.78 (4.15) (3.55-5.42)4.64±1.57 (4.82) (3.17-6.73)0.538
R7G6 mm4.65±2.15 (4.26) (3.34-6.24)4.91±1.81 (4.51) (3.36-6.39)0.4374.36±2.26 (4.06) (2.83-5.35)4.22±2.56 (3.65) (2.61-4.98)0.586
9 mm6.58±2.24 (6.67) (5.35-8.08)6.81±1.84 (6.87) (5.46-9.25)0.5156.27±1.96 (5.88) (5.26-7.32)6.18±2.32 (5.87) (4.82-7.18)0.845
12 mm7.96±2.38 (8.27) (6.81-9.51)8.07±1.83 (7.99) (6.80-9.49)0.8017.67±1.96 (7.72) (6.39-8.53)7.52±2.10 (7.34) (6.38-8.05)0.629
R7X6 mm6.16±2.54 (5.92) (4.68-7.67)6.72±2.07 (6.53) (5.14-8.16)0.1956.08±2.23 (6.14) (3.99-7.49)6.02±2.59 (5.94) (4.02-8.68)0.858
9 mm7.84±2.37 (7.80) (6.85-8.98)8.10±1.86 (7.92) (6.80-9.35)0.5047.70±1.84 (7.86) (6.51-8.35)7.81±2.32 (7.61) (6.39-8.97)0.731
12 mm8.79±2.48 (8.69) (7.15-10.43)8.86±1.73 (8.81) (7.80-9.85)0.8668.52±1.77 (8.49) (7.42-10.62)8.84±2.31 (8.57) (7.61-9.65)0.331
DOI: https://doi.org/10.2478/aoj-2025-0026 | Journal eISSN: 2207-7480 | Journal ISSN: 2207-7472
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Language: English
Page range: 275 - 283
Submitted on: Apr 1, 2025
Accepted on: Jun 1, 2025
Published on: Sep 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 Trung Nhu Nguyen, Vy T. T. Huynh, Huong Quynh Nguyen, published by Australian Society of Orthodontists Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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