Dental-craniofacial Characteristics of Southern Vietnamese People with Well-balanced Face on Cephalometric Films and Its Comparison with Caucasians and Northern Vietnamese Population.

OBJECTIVES: The objective of this study was to evaluate the dental-craniofacial measurements of the Southern Vietnamese people aged 18 to 25 with well-balanced face on cephalometric films.
MATERIALS AND METHODS: This cross-sectional study included 60 cephalometric tracings of students (30 males, 30 females). The cephalometric measurements were made on 34 angles, 26 distances, and 4 ratios of skeletal, dental, and soft tissue cephalometric analysis. The mean and standard deviation (SD) of the dental-craniofacial measurements were calculated and compared among male and female subjects and with Caucasian and the Northern Vietnamese population.
RESULTS: Among the Southern Vietnamese cephalometric tracing samples, the majority of the linear measurements were smaller in female than in male, while the angular and ratio measurements showed no significant difference. When compared with Caucasians, the cranial fossa lengths, the vertical facial heights, the lengths of maxilla and mandible, and the facial convexity of the Southern Vietnamese people were significantly smaller (P < 0.01), while the upper and lower incisors protrusion, and lip protrusion were larger (P < 0.01). The maxillary and mandibular protrusions, and mandibular rotational patterns were similar between these two groups. When compared with the Northern Vietnamese population, the mandibular plane angle and the upper and lower incisor protrusion of the Southern Vietnamese people were significantly larger (P < 0.05).
CONCLUSIONS: The dental-craniofacial measurements of the Southern Vietnamese people were different among male and female, and different than those of Caucasians and Northern Vietnamese population. Such differences should be taken into account when considering orthodontic and orthognathic treatment strategies. Copyright:

INTRODUCTION

People have their own perceptions of dental beauty, and to convey this into a treatment goal is difficult. Artists and healthcare professionals have attempted to define and create standards for “facial harmony.”[1] A well-balanced face is determined by the three factors: tooth position, bone patterns, and soft tissues.

To best perform a comprehensive evaluation and diagnosis for orthodontic and orthognathic treatments, a closer look at specific dental-craniofacial measurements is needed. Many authors have published common measurements of facial bones, teeth, and soft tissues on cephalometric films, such as Steiner, Downs, Ricketts, Holdaway, and Tweed.[23456] Another group of reseacher experts, including Scheideman, Celebi, Milošević, Goldsman, and Riedel proposed standardized measurement values based on age, sex, and ethnicity.[7891011] However, these studies focused mostly on the Caucasian ethnic group, which limited the extrapolation of the results to other ethnic groups.

Currently, in Vietnam, the literature on dental-craniofacial measurements is limited to only one study by Tran et al.[12] in 2016 that looked to establish the norms of Steiner’s analysis for the Northern Vietnamese people. However, more measurements of other cephalometric analysis are needed to identify the problems encountered in orthodontic diagnosis. Besides, there are some differences in dental-craniofacial characteristics between the Southern and Northern Vietnamese people and current data on dental-craniofacial measurements for the Southern Vietnamese population are lacking. As for the increasing demand for orthodontic and orthognathic treatment in Southern Vietnam, it is important to study and develop a dental-craniofacial measurement standard for the Southern Vietnamese population. The present study was conducted with the following objectives:

To establish standards for dental-craniofacial measurements for the Southern Vietnamese young adults.

To determine the sexual differences between the Southern Vietnamese males and females in dental-craniofacial characteristics.

To compare the dental-craniofacial differences with Caucasians and Northern Vietnamese population using various measurements.

MATERIALS AND METHODS

This cross-sectional study included 60 cephalometric tracings of students (30 males, 30 females) of the Odonto-Stomatology Department, Ho Chi Minh University of Medicine and Pharmacy, Vietnam, considering the following inclusion criteria: aged 18 to 25, well-balanced face, no history of previous orthodontic, prosthodontic treatments, or any surgical reconstruction or maxillofacial surgery.

The tracing landmarks were identified and reviewed by the study investigator who was an orthodontic master trainee and also a practicing dentist at the time. The trainee was closely supervised by a professional orthodontist on the team. The tracings were scanned to a research computer on 1:1 ratio, and digitized on a Scriptel digitizer using a user-defined analysis mode on the Vistadent OC Cephalometric Analysis software program on Window XP computer. The cephalometric measurements were made on 34 angles, 26 distances, and 4 ratios of skeletal, dental, and soft tissue measurements chosen from Tweed’s, Steiner’s, Downs’s, McNamara’s, Burstone’s, Ricketts’s, Rakosi’s, Schwarz’s, Jarabak’s, and Holdaway’s cephalometric analysis [Figures 1–8].

Figure 1

Cranial base assessment. 1. Ar - Ptm (//HP), 2. Ptm - N (//HP), 3. NSAr, 4. SArcGo

Figure 8

Soft tissue assessment. (A) 1. Gl - Sn - Pog’, 2. N’SnPog’, 3. N’PnPog’, 4. ∠α, 5. ∠α1, 6. ∠α2. (B) 7. Ls - SnPog’, 8. Li - SnPog’, 9. Ls - PnPog’, 10. Li - PnPog’, 11. Si - LiPog’, 12. Pog - Pog’

Vertical facial height assessment. 1. N - Me, 2. S - Go, 3. N - ANS, 4. ANS - Me

Maxillary skeletal assessment. 1. SNA, 2. N - A (//HP), 3. Co - A, 4. ANS - PNS (//HP), 5. N - ANS (⊥HP), 6. N - PNS (⊥HP)

Mandibular skeletal assessment. 1. SNB, 2. N - Pog (//HP), 3. Co - Gn, 4. Go - Pog, 5. B - Pog (//MP), 6. MP - HP, 7. FH - GoMe, 8. SN - GoGn, 9. Ar - Go, 10. ∠cGo

Maxillomandibular relation. 1. ANB, 3. ANS - Gn (⊥HP), 4. N - A - Pog, 5. PoOr - SGn, 7. PP - GoMe

Maxillary dentoalveolar assessment. (A) 1. U1 - NA, 5. U1 - SN, 6. U1 - PP, 7. A6 - Ptv, 8. Isi - PP (⊥PP), 9. u6 - PP (⊥PP). (B) 2. u1 - NA, 3. u1 - A (//FH), 4. Isi - APog

Mandibular dentoalveolar assessment. (A) 1. L1 - NB, 3. L1 - GoMe, 4. FMIA, 6. U1 - L1, 7. Iii - MP (⊥MP), 8. l6 - MP (⊥MP). (B) 2. l1 - NB, 5. Iii - APog

On tracing the samples, the landmarks and parameters were identified and measured on two separate occasions 1 week apart by the same researcher. The Intraclass Correlation Coefficient (ICC) index between two measurements was calculated. An ICC score of >0.85, which confirmed high degree of consistency, was required.

The means and standard deviations (SD) were determined for the total sample. The means and SD of measurements among the male and female subjects were compared using a 2-sample Student t-test using the SPSS 22. The level of significance was set at 0.05. In addition, the means and SD of measurements of the study tracing samples were compared with those measurements of the Caucasian population, published by Burstone, McNamara, Scheideman, and Legan and Burstone,[7131415] and of the Northern Vietnamese population published by Tran et al.[12] A 2-sample t-test was also used to assess the significance of difference.

RESULTS

The means, SD, and significant differences between males and females were provided for the skeletal, dental, and soft tissue measurements as shown in Tables 1–3, respectively. The measurement differences of the study tracing samples in comparison to those of Caucasians and North Vietnamese population are provided in Tables 4 and 5.

Table 1

Skeletal measurements

Measurements	Description	Unit	Male (n = 30)	Female (n = 30)	Both (n = 60)	P
			Mean ± SD	Mean ± SD	Mean ± SD
Cranial base assessment
Posterior cranial base	Ar - Ptm (//HP)	mm	30.49 ± 3.1	28.6 ± 2.24	29.55 ± 2.85	0.009
Anterior cranial base	Ptm - N (//HP)	mm	47.72 ± 3.87	46.61 ± 2.92	47.16 ± 3.44	0.214
Saddle angle	NSAr	(°)	123 ± 5.72	124 ± 4.97	123.5 ± 5.33	0.473
Articular angle	SArcGo	(°)	150.43 ± 6.06	148.23 ± 5.92	149.33 ± 6.04	0.16
Vertical facial height
AFH	N - Me	mm	116.59 ± 5.78	110.89 ± 5.83	113.74 ± 6.43	0.000
PFH	S - Go	mm	80.79 ± 5.64	75.84 ± 5.54	78.31 ± 6.08	0.001
UAFH	N - ANS	mm	52.97 ± 3.05	50.06 ± 2.55	51.51 ± 3.15	0.000
LAFH	ANS - Me	mm	64.53 ± 4.45	61.68 ± 4.12	63.1 ± 4.49	0.013
UAFH/LAFH	N - ANS/ANS - Me	%	82.42 ± 6.77	81.38 ± 5.18	81.9 ± 6	0.507
UAFH/AFH	N - ANS/N - Me	%	45.46 ± 2.05	45.17 ± 1.57	45.31 ± 1.82	0.546
LAFH/AFH	ANS - Me/N - Me	%	55.32 ± 2.08	55.6 ± 1.58	55.46 ± 1.84	0.552
PFH/AFH	S - Go/N - Me	%	69.33 ± 4.19	68.41 ± 3.78	68.87 ± 3.98	0.376
Maxillary skeletal assessment
Maxillary protrusion	SNA	(°)	83.45 ± 4.35	83.26 ± 2.98	83.36 ± 3.7	0.85
	N - A (//HP)	mm	0.5 ± 4.41	0.29 ± 2.88	0.39 ± 3.69	0.829
Effective MX length	Co - A	mm	80.51 ± 4.24	77.38 ± 3.97	78.95 ± 4.37	0.004
MX length	ANS - PNS (//HP)	mm	47.08 ± 3	45.71 ± 2.26	46.39 ± 2.72	0.052
UAFH	N - ANS (⊥HP)	mm	52.73 ± 3.11	49.9 ± 2.57	51.31 ± 3.17	0.000
UPFH	N - PNS (⊥HP)	mm	51.06 ± 3.02	48.97 ± 3.27	50.01 ± 3.29	0.013
Mandibular skeletal assessment
MD protrusion	SNB	(°)	80.73 ± 3.86	80.72 ± 2.69	80.72 ± 3.3	0.991
Chin protrusion	N - Pog (//HP)	mm	-2.31 ± 7.36	-2.5 ± 5.18	-2.4 ± 6.31	0.908
Effective MD length	Co - Gn	mm	111.44 ± 5.06	106.31 ± 5.46	108.87 ± 5.83	0.000
MD body length	Go - Pog	mm	74.99 ± 4.12	71.03 ± 4.24	73.01 ± 4.6	0.001
Chin depth	B - Pog (//MP)	mm	5.95 ± 1.21	5.14 ± 1.14	5.54 ± 1.23	0.010
MD plane angle	MP - HP	(°)	22.96 ± 4.84	23.68 ± 4.5	23.32 ± 4.64	0.551
MD plane angle	FH - GoMe	(°)	22.87 ± 4.56	23.43 ± 4.32	23.15 ± 4.41	0.623
MD plane angle	SN - GoGn	(°)	29.5 ± 4.49	29.71 ± 4.19	29.6 ± 4.3	0.85
MD ramus length	Ar - Go	mm	48.79 ± 4.76	46.44 ± 4.39	47.61 ± 4.7	0.051
Gonial angle	∠cGo	(°)	116.47 ± 5.36	118.40 ± 4.85	117.43 ± 5.16	0.148
Maxillomandibular relation
Relation of MX to MD	ANB	(°)	2.7 ± 2.38	2.54 ± 1.71	2.62 ± 2.06	0.757
Maxillomandibular differential	|CoA - CoGn|	mm	31.07 ± 3.13	28.96 ± 3.53	30.02 ± 3.47	0.017
LAFH	ANS - Gn (⊥HP)	mm	63.37 ± 4.43	60.54 ± 4.1	61.95 ± 4.46	0.013
Facial convexity	N - A - Pog	(°)	3.6 ± 5.59	3.67 ± 4.15	3.63 ± 4.88	0.958
Y axis	PoOr - SGn	(°)	60.17 ± 2.69	59.73 ± 3.35	59.95 ± 3.02	0.583
Bjork's sum	NSAr + SArcGo + ∠cGo	(°)	389.93 ± 4.76	390.67 ± 4.48	390.30 ± 4.60	0.541
PP - MD plane angle	ANS.PNS- GoMe	(°)	20.87 ± 4.68	22.90 ± 4.28	21.88 ± 4.56	0.084

Table 3

Soft tissue measurements

Measurements	Description	Unit	Male (n = 30)	Female (n = 30)	Both (n = 60)	P
			Mean ± SD	Mean ± SD	Mean ± SD
Total convexity except nose	Gl - Sn - Pog’	(°)	10.09 ± 4.85	8.79 ± 3.92	9.44 ± 4.42	0.258
Angle of facial convexity	N’SnPog’	(°)	164.33 ± 5.21	165.73 ± 4.05	165.03 ± 4.68	0.25
Total convexity with nose	N’PnPog’	(°)	134.5 ± 3.65	135.5 ± 3.29	135 ± 3.48	0.269
Nasolabial angle	∠α	(°)	94.63 ± 11.7	97.4 ± 8.3	96.02 ± 10.16	0.296
Columella tangent to postural horizontal	∠α1	(°)	16.11 ± 8.02	19.35 ± 6.74	17.73 ± 7.52	0.095
Upper lip tangent to postural horizontal	∠α2	(°)	78.79 ± 7.35	78.38 ± 5.62	78.59 ± 6.49	0.809
Upper lip protrusion	Ls - SnPog’	mm	4.8 ± 1.52	4.59 ± 0.98	4.69 ± 1.27	0.526
Lower lip protrusion	Li - SnPog’	mm	3.92 ± 1.75	3.65 ± 1.47	3.79 ± 1.61	0.519
Upper lip to E-line	Ls - PnPog’	mm	-2.26 ± 1.98	-1.96 ± 1.56	-2.11 ± 1.78	0.515
Lower lip to E-line	Li - PnPog’	mm	0.72 ± 1.92	0.81 ± 1.65	0.77 ± 1.78	0.846
Mentolabial sulcus depth	Si - LiPog’	mm	4.16 ± 0.77	3.89 ± 0.83	4.03 ± 0.81	0.195
Chin thickness	Pog - Pog’	mm	10.77 ± 1.69	10.59 ± 1.09	10.68 ± 1.41	0.624

Table 4

Comparison with Caucasians

Parameter (unit)	Sex	Vietnamese	Caucasians	Author	P
		Mean ± SD	Mean ± SD
Ar - Ptm (//HP) (mm)	M	30.49 ± 3.1	37.1 ± 2.8	Burstone	0.0000
	F	28.6 ± 2.24	32.8 ± 1.9	Burstone	0.0000
Ptm - N (//HP) (mm)	M	47.72 ± 3.87	52.8 ± 4.1	Burstone	0.0003
	F	46.61 ± 2.92	50.9 ± 3.0	Burstone	0.0000
ANS – Me(mm)	M	64.53 ± 4.45	74.6 ± 5.0	McNamara	0.0000
	F	61.68 ± 4.12	66.7 ± 4.1	McNamara	0.0000
N - ANS/ANS – Me (%)	M	82.42 ± 6.77	79 ± 5	Scheideman	0.0267
	F	81.38 ± 5.18	81 ± 5	Scheideman	0.7867
SNA (°)	M	83.45 ± 4.35	82.4 ± 3.9	Scheideman	0.3204
	F	83.26 ± 2.98	82.6 ± 3.6	Scheideman	0.4643
ANS - PNS (//HP) (mm)	M	47.08 ± 3	57.7 ± 2.5	Burstone	0.0000
	F	45.71 ± 2.26	52.6 ± 3.5	Burstone	0.0000
SNB (°)	M	80.73 ± 3.86	80.9 ± 3.4	Scheideman	0.8544
	F	80.72 ± 2.69	80.1 ± 3.0	Scheideman	0.4276
MP - HP (°)	M	22.96 ± 4.84	23.0 ± 5.9	Burstone	0.9811
	F	23.68 ± 4.5	24.2 ± 5.0	Burstone	0.7212
SN - GoGn (°)	M	29.5 ± 4.49	27.0 ± 4.8	Scheideman	0.0387
	F	29.71 ± 4.19	30.3 ± 4.7	Scheideman	0.6282
Go - Pog (mm)	M	74.99 ± 4.12	84.3 ± 3.8	Scheideman	0.0000
	F	71.03 ± 4.24	80.6 ± 4.0	Scheideman	0.0000
B - Pog (//MP) (mm)	M	5.95 ± 1.21	8.9 ± 1.7	Burstone	0.0000
	F	5.14 ± 1.14	7.2 ± 1.9	Burstone	0.0000
ANB (°)	M	2.7 ± 2.38	1.6 ± 1.5	Scheideman	0.0323
	F	2.54 ± 1.71	2.5 ± 1.8	Scheideman	0.9338
U1 - NA (°)	M	25.62 ± 5.77	21 ± 6	Scheideman	0.0031
	F	25.93 ± 4.96	19.1 ± 6.1	Scheideman	0.0000
L1 - NB (°)	M	26.95 ± 6.62	22.3 ± 4.8	Scheideman	0.0023
	F	28.45 ± 5.38	25.5 ± 5.3	Scheideman	0.0490
Gl - Sn - Pog’ (°)	Both	9.44 ± 4.42	12 ± 4	Legan & Burtone	0.0040
∠α (°)	M	94.63 ± 11.7	111.4 ± 11.7	Scheideman	0.0000
	F	97.4 ± 8.3	111.9 ± 8.4	Scheideman	0.0000
Ls - SnPog’ (mm)	Both	4.69 ± 1.27	3 ± 1	Legan & Burtone	0.0000
Li - SnPog’ (mm)	Both	3.79 ± 1.61	2 ± 1	Legan & Burtone	0.0000
Ls - PnPog’ (mm)	M	-2.26 ± 1.98	-6.8 ± 1.9	Scheideman	0.0000
	F	-1.96 ± 1.56	-5.8 ± 2.0	Scheideman	0.0000
Li - PnPog’ (mm)	M	0.72 ± 1.92	-3.9 ± 2.1	Scheideman	0.0000
	F	0.81 ± 1.65	-2.4 ± 2.2	Scheideman	0.0000
Si-LiPog' (mm)	Both	4.03 ± 0.81	4 ±2	Legan & Burtone	0.9172
Pog - Pog’ (mm)	M	10.77 ± 1.69	12.5 ± 1.8	Scheideman	0.0002
	F	10.59 ± 1.09	10.8 ± 1.6	Scheideman	0.5695

Table 5

Comparison with Northern Vietnamese

Parameter (unit)	Sex	Southern	Northern	P
		Mean ± SD	Mean ± SD
SNA (°)	M	83.45 ± 4.35	84.67 ± 3.24	0.2229
	F	83.26 ± 2.98	84.03 ± 2.89	0.3139
SNB (°)	M	80.73 ± 3.86	81.24 ± 3.34	0.5863
	F	80.72 ± 2.69	81.34 ± 2.86	0.3907
ANB (°)	M	2.7 ± 2.38	3.29 ± 1.27	0.2358
	F	2.54 ± 1.71	2.45 ± 1.36	0.8223
SN - GoGn (°)	M	29.5 ± 4.49	26.13 ± 3.68	0.0024
	F	29.71 ± 4.19	26.82 ± 5.42	0.0244
U1 - NA (°)	M	25.62 ± 5.77	25.3 ± 4.51	0.8117
	F	25.93 ± 4.96	24.36 ± 5.96	0.2720
u1 - NA (mm)	M	5.64 ± 2.09	4.23 ± 1.89	0.0081
	F	5.88 ± 1.48	4.12 ± 1.59	0.0000
L1 - NB (°)	M	26.95 ± 6.62	29.74 ± 6.04	0.0935
	F	28.45 ± 5.38	28.42 ± 6.13	0.9840
l1 - NB (mm)	M	6.18 ± 2.15	5.14 ± 1.88	0.0508
	F	5.94 ± 1.71	4.31 ± 2.26	0.0026
U1 - L1 (°)	M	124.72 ± 9.2	121.3 ± 7.58	0.1215
	F	123.09 ± 7.84	123.98 ± 9.11	0.6865

Among the Southern Vietnamese cephalometric tracing samples, the majority of the linear measurements were smaller in female when compared with male, while the majority of the angular and ratio measurements showed no significant difference.

In comparison with Caucasians, the cranial fossa lengths, the vertical facial heights, the lengths of maxilla and madible, and the facial convexity of the Southern Vietnamese people were significantly smaller, while the upper and lower incisors protrusion, and the upper and lower lips protrusion were larger. Though, the maxillary and mandibular protrusions, and the mandibular rotational patterns were similar between Caucasians and the Southern Vietnamese group.

When compared with the Northern Vietnamese people, the mandibular plane angle in relation to the cranial base (SN - GoGn) and the upper and lower incisors protrusion of Southern Vietnamese were larger.

DISCUSSION

SKELETAL MEASUREMENTS

The growth of the cranial base can influence the height and depth of the upper face and position of the upper teeth during orthodontic treatments.[16] Therefore, it is essential to assess the anterior and middle cranial fossa length (Ptm - N (//HP)), (Ar - Ptm (//HP)), and flexure (NSAr, SArcGo).

Evaluation of the vertical patterns and proportions has a major role in the overall harmony of the face.[17] Vertical dimensions include Anterior Facial Height (AFH) and Posterior Facial Height (PFH). Anterior Facial Height (AFH) is divided into upper anterior facial height (UAFH) and lower anterior facial height (LAFH).

The skeletal components of the maxilla and mandible were assessed in relation to their length (Co-A, ANS-PNS, and Co - Gn, Go - Pog, B - Pog (//MP), Ar - Go), sagittal positions relative to the cranium (SNA, N - A(//HP), and SNB, N - Pog (//HP)), vertical positions (N - ANS (⊥HP), N - PNS (⊥HP)), and rotational pattern (MP - HP, FH - GoMe, SN - GoGn, ∠cGo).

After the maxilla and mandible were individually assessed, their interrelationship was evaluated (ANB, |CoA - CoGn|, N - A - Pog). The lower anterior face height (ANS - Gn (⊥HP)) was a representation of the sum of the anterior dento-alveolar heights of the two jaws and skeletal base inclination. The growth axis (PoOr - SGn) and the Bjork’s sum (NSAr + SArcGo + ∠cGo) were assessed to predict the probable direction and pattern of future facial growth.

Our results showed that the majority of the linear measurements among the Southern Vietnamese tracing samples were less in female than in male (P < 0.05), except for Ptm - N (//HP), N - A (//HP), ANS - PNS (//HP), N - Pog (//HP), and Ar - Go which showed no significant difference (P > 0.05). The majority of the angular and ratio measurements showed no significant difference between both sexes (P > 0.05) [Table 1]. This revealed that the skeletal dimensions in female was smaller than in male, while the facial patterns, the maxilla, and mandible in relation to the cranium and their interrelationship were similar between both sexes.

In comparison with Caucasians, the cranial fossa lengths, the vertical facial heights, and the maxilla and mandible lengths were shorter among the Southern Vietnamese population (P < 0.001), while the maxillary and mandibular protrusions, and the mandibular rotational patterns showed no significant differences (P > 0.05) [Table 4]. When compared with the Northern Vietnamese people, the mandibular plane angle (SN-GoGn) of the Southern Vietnamese were larger (P < 0.05) [Table 5].

DENTAL MEASUREMENTS

The inclination and sagittal position of the maxillary and mandibular incisors in relation to both the skeletal base and the cranium (U1 - NA, u1 - NA, U1-A(⊥FH), Isi - APog, U1 - SN, U1 - PP, and L1 - NB, l1 - NB, L1 - GoMe, FMIA and Iii - APog) were calculated, and the vertical position of the incisal edge and the first molar cusp tip (Isi - PP (⊥PP), u6 - PP (⊥PP) and Iii –MP(⊥MP),l6 –MP(⊥MP)) were assessed. The relation of the pterygomaxillary fissure and the maxillary first molar was done to evaluate the amount of alveolar arch length available for molar distalization mechanics (A6 - Ptv).

Our results indicated that most of the dental measurements showed no significant difference between both sexes (P > 0.05), except for Iii - MP (⊥ MP) and l6 - MP (⊥ MP), shown to be higher in males than in females (P < 0.01) [Table 2].

Table 2

Dental measurements

Measurements	Description	Unit	Male (n = 30)	Female (n = 30)	Both (n = 60)	P
			Mean ± SD	Mean ± SD	Mean ± SD
Maxillary dentoalveolar assessment
Incisor to NA	U1 - NA	(°)	25.62 ± 5.77	25.93 ± 4.96	25.77 ± 5.34	0.822
	u1 - NA	mm	5.64 ± 2.09	5.88 ± 1.48	5.76 ± 1.8	0.608
Incisor to A-vert	u1 - A (//FH)	mm	5.16 ± 2.15	5.49 ± 1.65	5.32 ± 1.91	0.505
Incisor to A-Pog	Isi - APog	mm	6.37 ± 2.09	6.64 ± 1.62	6.5 ± 1.86	0.576
Incisor to SN plane	U1 - SN	(°)	109.06 ± 6.47	109.19 ± 4.81	109.13 ± 5.65	0.93
Incisor to PP plane	U1 - PP	(°)	61.87 ± 6.48	62.90 ± 5.07	62.38 ± 5.79	0.494
Molar to Ptv	A6 - Ptv	mm	17.59 ± 3	17.01 ± 3.42	17.3 ± 3.2	0.484
Upper incisor-PP	Isi - PP (⊥PP)	mm	27.08 ± 2.27	26.27 ± 2.44	26.67 ± 2.37	0.187
Upper molar-PP	u6 - PP (⊥PP)	mm	23.67 ± 2.09	22.8 ± 1.67	23.24 ± 1.93	0.077
Mandibular dentoalveolar assessment
Incisor to NB	L1 - NB	(°)	26.95 ± 6.62	28.45 ± 5.38	27.7 ± 6.02	0.339
	l1 - NB	mm	6.18 ± 2.15	5.94 ± 1.71	6.06 ± 1.93	0.632
Incisor to mandibular plane	L1 - GoMe	(°)	96.37 ± 6.48	96.97 ± 5.81	96.67 ± 6.11	0.707
Frankfort mandibular incisal angle	FMIA	(°)	60.83 ± 6.93	59.43 ± 6.23	60.13 ± 6.57	0.414
Incisor to A-Pog	Iii - APog	mm	3.29 ± 2.12	3.68 ± 1.64	3.48 ± 1.89	0.423
Interincisor angulation	U1 - L1	(°)	124.72 ± 9.2	123.09 ± 7.84	123.9 ± 8.52	0.463
Lower incisor to MP	Iii - MP (⊥MP)	mm	39.62 ± 2.72	37.76 ± 2.1	38.69 ± 2.58	0.004
Lower molar to MP	l6 - MP (⊥ MP)	mm	32.28 ± 2.4	30.02 ± 2.38	31.15 ± 2.63	0.001

In comparison to Caucasians, the upper and lower incisors in relation to the skeletal base were larger in the Southern Vietnamese people (P < 0.05) [Table 4]. When compared with the Northern Vietnamese people, the Southern people also had the upper and lower incisors more protrusive (P < 0.05) [Table 5].

SOFT TISSUE MEASUREMENTS

As the orthodontic treatment influences the position of teeth and jaws, which in turn influences the morphology of the overlying facial soft tissues, the evaluation of the soft tissue components of the face plays an important role in diagnosis and treatment planning. Soft tissue analysis includes evaluating the facial convexity (Gl - Sn - Pog’, N’SnPog’, N’PnPog’), nasolabial angle (∠α, ∠α1, ∠α2), lips protrusion (Ls - SnPog’, Li - SnPog’), the prominence of the lips relative to E lines (Ls - PnPog’, Li - PnPog’), the mentolabial sulcus depth (Si - SnPog’), and the soft tissue chin thickness (Pog - Pog’).

As shown in Table 3, our results revealed that soft tissue measurements showed no significant difference between both sexes among the Southern Vietnamese people (P > 0.05).

However, when compared with Caucasians, the facial convexity was less in the Southern Vietnamese population, while upper and lower lips protrusion were larger (P < 0.01) [Table 4].

CONCLUSIONS

The dental-craniofacial standards among the Southern Vietnamese people were different between male and female, and different than Caucasians and the Northern Vietnamese group. Such differences should be taken into account when considering orthodontic and orthognathic treatment strategies for Southern Vietnamese patients.

FINANCIAL SUPPORT AND SPONSORSHIP

Nil.

CONFLICTS OF INTEREST

There are no conflicts of interest.

AUTHORS CONTRIBUTIONS

TT.T.H conceived the ideas. TT.T.H and QT.T.L collected and analysed the data. TT.T.H and QT.T.L contributed to the writing, editing and review.

ETHICAL POLICY AND INSTITUTIONAL REVIEW BOARD STATEMENT

This study was approved by the Research Committee of the University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam. Approval number of the present study was 2258/QƉ-ƉHYD from the University.

PATIENT DECLARATION OF CONSENT

The consent not required as student’s identify is not disclosed or compromised.

DATA AVAILABILITY STATEMENT

All data generated or analysed during this study are included in this article.