Angular Photogrammetric Soft Tissue Facial Profile Analysis of Bangladeshi Young Adults

Nasofrontal angle (G-N-Nd)

The present study showed that the mean value of nasofrontal angle for 200 samples was 132.39° ± 8.015°. The nasofrontal angle (G-N-Nd) showed gender dimorphism (P = 0.00; males = 128.47°, females = 136.32°). Statistically significant (P < 0.05) and the higher mean value was found in females as compared to males. The mean value of the study was much closer to the values in studies by Devi et al. (Bengali, west)^[10] males = 128.06° and females = 139.568°, Ezeuko and Eboigbe (adult Bini ethnicity of Nigeria)^[8] males = 128° ± 0.6° and females = 133.8°, Ferdousi et al. (Bangladeshi Garo)^[9] males = 129.56° ± 7.96° and females = 137.96° ± 4.79°, and Zaib et al. (Pakistani)^[5] males = 130.1667° ± 5.305° and females = 133.8567° ± 5.573°.

The mean values of the current study were lesser than the values in studies by Reddy et al. (North Indian)^[11] males = 136.71° ± 3.64° and females = 144.33° ± 1.75°, Anić-Milosević et al. (Croatian)^[4] males = 136.38 ± 6.71° and females = 139.11° ± 6.35°, Fernandez-Riveiro et al., (Spanish)^[12] males = 138.57° ± 6.81° and females = 141.98° ± 6.06°, Malkoç et al. (Turkish)^[13] males = 146.03° ± 8.19° and females = 148.61° ± 6.66°, and Ajami et al. (Iranian)^[14] males = 144.67° and females = 148.78°. The mean value in the present study was greater than the study by Oghenemavwe et al. (Urhobos),^[15] with values of males = 121.75° ±9.07° and females = 127.85° ± 8.50°.

Total facial angle or facial convexity including the nose (N-Prn-Pg)

The mean value of total facial convexity of the total population of Bangladeshi young adults was 127.38° ± 4.533°. The value for males was 27.29° ± 4.421° and females was 127.49° ± 4.747°, with gender differences not being statistically significant. These values were similar to the values given by Reddy et al. (North Indian)^[11] 127.71° ± 1.97° for males and 127.11° ±1.81° for females but lesser in comparison to those in studies by Pattanaik and Pathuri (Southern India; males = 130.82° and females = 131.71°)^[16] and Anić-Milosević et al. (Croatian; males = 130.47 ± 3.73° and females = 130.19 ± 3.47°).^[4] Fernández-Riveiro et al.^[12] and Bishara et al.^[17] measured the angle from glabella, not from nasion and found higher values. Bishara et al.^[17] stated that between 25 and 45 years of age, the angle increased by 2.1° and 1.3° in males and females, respectively, reflecting either a more vertical growth of the tip of the nose or a more forward movement of soft tissue pogonion.

Facial angle or facial convexity excluding the nose (G-Sn-Pg)

The profile angle was used to assess the convexity or concavity of the facial profile. According to Bergmann (1999),^[18] Class I participants presented an angle ranging from 165° to 175°. The average value of this angle in this study was 165.43° ± 4.768°. Mean value for males was 165.22° ± 5.040° and for females was 165.63° ± 4.514° which was similar to the values given by Devi et al. (Bengali; males = 165.138° and females = 168.52°)^[10] and Moshkelgosha et al. (Persian; males = 165.17 and females = 165.9°).^[19] This value was slightly less than the values given by Anić-Milosević et al. (males = 168.78 ± 4.9° and females = 169.05 ± 4.69°)^[4] and Malkoç et al. (males = 170.60 ± 6.15° and females = 168.78 ± 5.44°).^[13]

It was suggested that Bangladeshi males may have slightly more convex face compared to females; however, in this study, no gender dimorphism was found.

Nose tip angle (N-Prn-Cm)

In this study, the average value of nose tip angle was 70.61° ± 5.433°. Mean value for males was 70.90° ± 6.744° and for females was 70.34 ± 3.715°. These values were lesser than those in studies by Reddy et al. (males = 75.09° ± 3.17° and females = 75.35° ± 3.08°),^[11] Anić-Milosević et al. (males = 79.85 ± 6.36° and females = 84.12 ± 5.2°),^[4] and Moshkelgosha et al., (males = 79.6° and females = 84.7°).^[19] According to Lines et al., most acceptable values of the angle fall between 60° and 80°.^[20] A sharper nasal tip in Bangladeshi population was due to decreased nasolabial angle. No pronounced differences were observed in male and female values.

Nasolabial angle (Cm-Sn-Ls)

The nasolabial angle evaluates the relationship of the nasal base and upper lip. Because its magnitude depends on the anteroposterior position and inclination of the upper anterior teeth, it can be altered by orthodontics or orthognathic surgery.^[21] According to Bergman,^[18] the ideal value of this angle should be 102° ±8°. This was used as part of the extraction decision. In the study of Talass et al.^[22] of Class II malocclusion participants where premolars were extracted, the upper incisors were retracted 6.7 mm on average, and the angle increased on average 10.5° with orthodontic treatment (1.6° for each millimeter of incisor retraction).

In the present study, the average value of nasolabial angle of Bangladeshi sample was found to be 92.78° ± 8.521°, with values of 94.09° ±9.804° for males and 91.44° ± 6.924° for females. These were close to the mean values given by Zaib et al. in a Pakistani population (males = 95.8333° ± 6.131° and females = 92° ± 7.37°)^[5] and by Ferdousi et al. in a Bangladeshi Garo population (males = 91.28° ± 12.98° and females = 91.92° ± 8.90°).^[9] The values were lesser than those in studies by Reddy et al. (males = 102.32° ± 4.69° and females = 101.50° ± 4.39°),^[11] Anić-Milosević et al. (males = 105.4° ± 9.5° and females = 109° ± 7.8°),^[4] and Moshkelgosha et al. (males = 107.28° and female = 111.2°).^[19] This can be attributed to the fact that the Bangladeshi population has a much fuller profile in comparison to the Caucasian. No Significant sexual dimorphism was observed.

Nasomental angle (N-Prn/N-Pg)

According to Lines et al., nasomental angle (N– Prn/N– Pg) is esthetically most acceptable within a range of 20°–30°.^[20] Statistically significant gender differences showed that a less prominent nose in relation to the chin is preferable in females and the opposite in males. Clements stated that the nasal prominence angle (nasomental angle) was around 30° or less in most faces which was illustrated in art throughout history.^[23] According to Hinds and Kent, the normal value is between 23° and 37°, with an average of approximately 30°.^[24] In the present study, mean value was 32.58° for total sample, 32.69° ± 3.268° for males and 32.49° ± 3.410° for females. The values were lesser than in Reddy et al.’s study (males = 34.38° ± 1.77° and females = 33.69° ± 1.37°)^[11] and in Ferdousi et al.’s study (males = 40.27° ± 4.54° and females = 38.67 ± 4.05°)^[9] but greater than in Pattanaik and Pathuri study (males = 27.11° and females = 26.58°)^[16] and Anić-Milosević et al. study (males = 29.53° ± 2.51° and females = 30.36° ± 2.38°).^[4] This could probably be attributed to the observation that the Bangladeshi population has less prominent nose than North Indian, Bengali population, but more than Caucasian European population. Bangladeshi population has a more convex total facial profile in comparison to the white European population. No significant gender differences were found.

Mentolabial angle (Li-Sm-Pg)

Mentolabial angle also showed great variability. The uprighting of the lower incisors tends to enlarge the angle.^[18] The mean value according to Burstone is 122.0° ± 11.7°.^[25] In the present study, greatest variability was found for this angle. The average value of mentolabial angle for overall population was 120.28° ± 15.248°, 116.91° ± 14.604° for males and 123.66° ± 15.108° for females, comparable to values of Zaib et al.’s study with values of 110.73° ± 12.784° for males and 125.2667° ± 7.570° for females.^[14] The mean value of the present study was less than the values given by Ajami et al. (males = 131.82° and females = 132.32°)^[14] and Anić-Milosević et al. (males = 129.3° ± 9.5°, females = 134.5° ± 9°).^[4] Lines et al. in a study of Silhouettes reported that the mentolabial angle ranged between 120° and 130°.^[20] They found that deeper mentolabial sulci were preferred in males. In this study, the females had a shallower mentolabial angle than the males which is in accordance with the profile preferences.

Projection of upper lip to chin (N-Pg/N-Ls)

Projection of upper lip to chin had a mean value of 9.15° ± 2.307° for overall sample, 9.23° ± 2.399° for males and 9.06° ± 2.32° for females which was larger than the values of 8.61° for males and 8.092° for females reported by Devi et al.^[10] and 6.98° ± 2.29° for males and 7.17° ± 1.71° for females reported by Anić-Milosević et al.^[4] Bangladeshi population had a much fuller profile with differences between gender not being statistically significant.

Upper lip angle (Sn-Ls/Sn-Pg)

The angle that reflects the position of the upper incisors and the thickness of the soft tissue overlying these teeth is the upper lip angle.^[26] In the present study, the mean value for this angle was 19.23° ± 7.030°. The average value for males was 18.71° ± 7.97° and for females was 19.67° ± 5.992° which was larger than the values given by Devi et al. (males = 12.846° and females = 16.528°)^[10] and Anić-Milosević et al. (males = 11.70° ±6.20° and females = 12.90° ± 4.82°).^[4] The present study showed no significant gender differences for this angle.

Projection of lower lip to chin (N-Pg/N-Li)

Lower lip angle was also measured from Nasion. The mean value was 4.84° ± 1.648°. The average value for males was 4.71° ± 1.445° and for females was 4.93° ± 1.865° which was almost similar to the value given by Pattanaik and Pathuri (males = 4.2° and females = 4.18°)^[16] and greater than the value given by Anicy-Milosevicy (males = 3.27° ± 1.79° and females = 3.69 ± 1.39°). Differences between genders were not statistically significant.