Table 3.22: The regression equation of distance and angle variables Distances
and angles
y : X-Ray, x: photographs Equation p (t-test) r r2 N-Gn y= 1,08*x – 10,08 0,000 0,8767 76,86%
N-Sn y= 0,89*x + 7,55 0,000 0,8663 75,05%
Sn-Gn y= 1,07*x – 7,98 0,000 0,8771 76,93%
Gl-Sn y= 1,03*x – 5,68 0,000 0,890 79,21%
Li-E y= 1,00*x + 0,02 0,000 0,8451 71,42%
Li-S y= 0,97*x + 0,03 0,000 0,7929 62,87%
Ls-E y= 0,90*x + 0,09 0,000 0,7509 56,39%
Ls-S y= 0,77*x + 0,38 0,000 0,7472 55,83%
Gl-Sn-Pg y= 0,86*x + 22,51 0,000 0,7630 58,22%
Li-B-Pg y= 1,15*x – 19,44 0,000 0,7920 62,73%
Pn-N-Pg y= 0,82*x + 5,73 0,000 0,7344 53,93%
N-Sn-Pg y= 1,12*x – 18,57 0,000 0,8283 68,61%
Pn-N-Sn y= 1,14*x – 2,08 0,000 0,8135 66,18%
Sn-Pn-N y= 1,14*x – 14,24 0,000 0,7472 55,83%
N-Pn-Pg y= 0,97*x + 4,77 0,000 0,8679 75,33%
When the results of distances and angles measured on photographs were used to predict the value on cephalometric radiographs, we found that the regression equations were statistically significant (p<0.05) with value r at high level (above 0.7).
Chapter 4
4.2. Some morphological characteristics of head and face on the frontal cephalometric radiographs taken remotely and standardized photographs
The results of Chart 3.1 showed majority of subjects had oval-shaped face (65%), followed by the square-oval-shaped face (23%) and triangular-shaped face (12%). We compared our results with some other authors in the world and in Vietnam. According to Ibrahimagie and V.Jerolimov with the study of 1000 subjects in Zenica, Bosnia and Herzegovina aged 17-24 years old, the percentages of oval-shaped, square-shaped and triangular-shaped face were 83%, 10%
and 9%, respectively. A previous study in Vietnam conducted on 142 students showed that the percentages of oval-shaped, square-shaped and triangular-shaped face were 65.7%, 24% and 10.3%, respectively. Those results were consistent with our results. And with the classification of face based on total facial index, we found that the person whose low value will have short and wide face.
The average values of ft-ft, zy-zy and go-go of this study were 140.67±6.18mm, 125.53±5.97mm, 145.77±6.78mm, respectively.
Comparing with the results of some other authors in Vietnam, we concluded that there was no significant difference of these indicators.
However, comparing with the results of some authors in the world, the results showed that the width of temporal bones and lower jaws was significantly greater in Turkish subjects ; conversely, the with between cheekbones was smaller in the subjects in Zenica, Bosnia and Herzegovina and Latvia. So, the facial indicators differ among the races. In our study, all dimensions of male were greater than female, these differences were statistically significant (Table 3.1 and 3.2). These result was quite similar to the results of other authors in the world as well as in Vietnam…
Table 3.6 showed that almost the values of the face width measured in male were greater than female (p<0.05). These results were entirely consistent with the study of Truong Nhu Ngoc Vo. Comparing the craniofacial indicators on left and right sides in male and female using frontal cephalometric radiographs taken remotely (Table 3.7), all results showed that there were differences of average values between the left and right sides (p<0.05), that is, both male and female, the average values on left side were higher than right side. These results were entirely consistent with the results of other authors.
Comparing the measurement through frontal standardized photographs with the measure ment through frontal cephalometric radiographs taken remotely, the results showed that the indicators measured on the photographs were statistically higher than those measured on radiographs (p<0.05, t-test). However, the results of Pearson correlation coefficient of two measurement methods were at low level (medium or weak with r<0.5). Therefore, we was unable to draw up a linear regression equation that predict the relationship between two measurement methods.
4.3. Some craniofacial indicators on lateral digital standardized photographs and lateral cephalometric radiographs taken remotely
The average distances from the lips to the S-line and E-line measured in male were greater than female, except Li-E (Table 3.9).
However, these differences were not much, so that p>0.05 (t-test).
The results of Table 3.10 showed that almost angles measured on the lateral standardized photographs in female were greater than male, and these differences were statistically significant (p<0.05). Our comment was similar to the comments of other Vietnamese authors who research on lateral standardized photographs.
On standardized photographs, there was no difference of values of total facial index, nasal index and mandibular index between male and female (Table 3.11). However, according to Martin’s classification of these indicators, our results showed that there were differences of nasal index and mandibular index between male and female. These results differ significantly from the results of Truong Nhu Ngoc Vo (2010) that conducted on 143 students. However, the reason as described above may be due to differences of inclusion criteria between two studies.
SNA and SNB, ANB angles in the upper boundary of the average values compared with Caucasians, this proved that Vietnamese people are not protruding. Our comment was similar to comments of some other authors who research on lateral cephalemetric radiographs. There was no difference with the results of studies in the world. However, comparing to the other Asian races such as Japan, Korea and India, there were differences of almost indicators of hard tissue (p<0.05). This confirmed that the representative indicators for each country are essential and we should not apply simultaneously many research results. These results of our study were similar to some other studies.
Table 3.18 showed that the average value of mentolabial angle Li-B’-Pg of male and female were 133.430 and 134.870, respectively.
Comparing with the Scheiderman’s study (1220 in male and 1280 in female), our results were greater. So that, the B’-point in subjects of our research was less concave, or in other words, the protruding of chin in subjects of our study was less than Caucasians.
The research results showed that there were differences of indicators of upper lip, the protrusion of upper lip and the thickness of upper lip on soft tissue between Vietnamese and European in study of Holdaway (1983) (Table 3.18). The protrusion and thickness of upper lip of Vietnamese students were greater than the white race.
The distance indicators on soft tissue measured on lateral cephalometric radiographs were differ significantly between Vietnamese and Iraqi as well as Turkish. However, our results were similar to Japanese in study of Alcade R.E (2000).
The value of thickness of upper lip in our subjects was smaller than three other Asian races, especially the groups of Iraqi and Japanese. The nasal protrusion of Vietnamese students was less than Iraqi and Turkish, but the distance from inferior border of the ala of the nose to H-line was greater. The cause may be due to the more protruding of the Vietnamese students’ chin.
& Burstone, we found that our results were entirely simlilar to Chinese. The angle displays the facial protrusion of Yemeni was smaller than our result but the maxillary protrusion was greater significantly (p<0.05). The protrusion of upper lip of Yemeni was smaller than our result. This maybe because chin of Vietnamese protruding more than Yemeni. And comparing to the other authors such as Line, Scheiderman, we found that the people whose harmonious faces had the more lower facial protrusion, lower or more obtuse nose; whereas, comparing to the quite harmonious face groups, those had less lower facial protrusion, higher or more acute nose.
The average values of Cm-Sn-Ls angle of male and female in our study were 90,480±6,290 và 94,550±6,180, respectively. These values
were in the lower boundary of results for European (Male: 91.670, female: 97.410 and European standards: male 90-950, female: 95-1100). These showed that the facial forms of our subjects were similar with European, but the assessment criterion were differ, so that we could not rigidly apply it.
CONCLUSION
1. Some morphological characteristics of head and face on the frontal cephalometric radiographs taken remotely and standardized photographs
- On frontal digital standardized photographs
+ Percentages of oval, square, triangular face were 65%, 23%, 12%, respectively.
+ Horizontal and vertical dimensions of the face in male were greater than female. And between facial forms, there were differences of horizontal dimentions.
- On cephalemetric radiographs
+ Almost craniofacial indicators in male were greater than female.
+ The values on the left side were greater than right side.
2. Some craniofacial indicators identified on lateral digital standardized photographs and lateral cephalemetric radiographs
- On lateral cephalometric radiographs
+ The values of dimensions, angles measured on hard tissue of male and female were similar, such as SNA angle (male: 83.880, female: 83.540), SNB angle (male: 80.720, female: 80.360), ANB angle (male: 3.160, female: 3.180), U1-L1 angle (male: 120,80, female: 120,730).
+ Almost values of angles on soft tissue of female were greater than male, such as Sn-Pn-N’ angle (male: 101.250, female: 104.950), Cm-Sn-Ls angle (male: 90.480, female: 94.550), N’-Sn-Pg’ angle (male: 161.140, female: 164.380), angle (male: 136.10, female: 138.20).
+ There was no close relationship between soft tissue and hard tissue.