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

Trung Nhu Nguyen

Trung Nhu Nguyen

Faculty of Odonto-Stomatology, Pham Ngoc Thach University of MedicineHo Chi Minh City, Vietnam
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Nguyen, Trung Nhu
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Vy T. T. Huynh

Vy T. T. Huynh

Faculty of Odonto-Stomatology, Pham Ngoc Thach University of MedicineHo Chi Minh City, Vietnam
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Huynh, Vy T. T.
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Huong Quynh Nguyen

Huong Quynh Nguyen

Faculty of Odonto-Stomatology, Pham Ngoc Thach University of MedicineHo Chi Minh City, Vietnam
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Nguyen, Huong Quynh
  
Sep 01, 2025
Mandibular buccal shelf asymmetry and bone density in vietnamese adults: a CBCT study's Cover Image
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Published Online: Sep 01, 2025
Page range: 275 - 283
Received: Apr 01, 2025
Accepted: Jun 01, 2025
DOI: https://doi.org/10.2478/aoj-2025-0026
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© 2025 Trung Nhu Nguyen et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

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)

Site Level Class I BP Class III P (I vs III)
R6G 6 mm Mean±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
R6G 9 mm Mean±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
R6G 12 mm Mean±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
R6X 6 mm Mean±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
R6X 9 mm Mean±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
R6X 12 mm Mean±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
R7G 6 mm Mean±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
R7G 9 mm Mean±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
R7G 12 mm Mean±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
R7X 6 mm Mean±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
R7X 9 mm Mean±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
R7X 12 mm Mean±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

Site Level Class 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)
R6G 6 mm –0.024, 0.898 –0.031, 0.871 –0.291, 0.119 –0.174, 0.359
R6G 9 mm 0.057, 0.766 0.067, 0.725 –0.146, 0.441 –0.310, 0.095
R6X 9 mm 0.169, 0.371 –0.056, 0.769 –0.167, 0.378 –0.253, 0.177
R7X 12 mm –0.087, 0.646 –0.002, 0.991 –0.147, 0.439 0.003, 0.986

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

Site Level Class 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)
R6G 6 mm 1.57±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 mm 2.13±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 mm 2.77±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
R6X 6 mm 2.09±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 mm 3.30±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 mm 4.19±1.66 (4.15) (3.11-4.96) 4.68±1.81 (4.89) (3.58-5.74) 0.063 4.48±1.78 (4.15) (3.55-5.42) 4.64±1.57 (4.82) (3.17-6.73) 0.538
R7G 6 mm 4.65±2.15 (4.26) (3.34-6.24) 4.91±1.81 (4.51) (3.36-6.39) 0.437 4.36±2.26 (4.06) (2.83-5.35) 4.22±2.56 (3.65) (2.61-4.98) 0.586
9 mm 6.58±2.24 (6.67) (5.35-8.08) 6.81±1.84 (6.87) (5.46-9.25) 0.515 6.27±1.96 (5.88) (5.26-7.32) 6.18±2.32 (5.87) (4.82-7.18) 0.845
12 mm 7.96±2.38 (8.27) (6.81-9.51) 8.07±1.83 (7.99) (6.80-9.49) 0.801 7.67±1.96 (7.72) (6.39-8.53) 7.52±2.10 (7.34) (6.38-8.05) 0.629
R7X 6 mm 6.16±2.54 (5.92) (4.68-7.67) 6.72±2.07 (6.53) (5.14-8.16) 0.195 6.08±2.23 (6.14) (3.99-7.49) 6.02±2.59 (5.94) (4.02-8.68) 0.858
9 mm 7.84±2.37 (7.80) (6.85-8.98) 8.10±1.86 (7.92) (6.80-9.35) 0.504 7.70±1.84 (7.86) (6.51-8.35) 7.81±2.32 (7.61) (6.39-8.97) 0.731
12 mm 8.79±2.48 (8.69) (7.15-10.43) 8.86±1.73 (8.81) (7.80-9.85) 0.866 8.52±1.77 (8.49) (7.42-10.62) 8.84±2.31 (8.57) (7.61-9.65) 0.331
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