3.1 Age distribution and number of teeth of the experimental population
After statistics, it was found that the distribution was relatively uniform, including 88 males and 72 females, as shown in Table 1.
Table 1 Age and number of teeth of experimental population
Age group(years)
|
number of people
|
Number of teeth (pcs)
|
20~29
|
38
|
228
|
30~39
|
42
|
252
|
40~49
|
41
|
246
|
50~59
|
39
|
234
|
3.2 Chromaticity value of each tooth position
The obtained chromaticity values were statistically analyzed, and it was obtained that each chromaticity value obeyed the ordinary distribution law and was described by the mean ± standard deviation (`x±s). The results are shown in Table 2 and Table 3. There was no statistical difference in the chromaticity values of teeth with the same name between different genders (P > 0.05).
Table 2 Measurement results of chromaticity value of each tooth position(x̄ ±s)
tooth
|
number of teeth(pcs)
|
L*
|
a*
|
b*
|
right central incisor
|
160
|
72.30±4.26
|
-0.57±0.39
|
14.35±2.93
|
right lateral incisors
|
160
|
69.53±4.83
|
0.17±0.69
|
18.37±3.35
|
right canine
|
160
|
64.71±4.20
|
1.35±0.66
|
23.71±3.25
|
left central incisor
|
160
|
73.03±4.58
|
-0.51±0.31
|
14.65±3.51
|
left lateral incisors
|
160
|
70.39±4.55
|
0.27±0.56
|
18.82±4.37
|
left canine
|
160
|
65.57±4.20
|
1.44±0.56
|
23.57±3.37
|
Table 3 The measurement results of the chromaticity value of each tooth position in different genders(x̄±s)
Gender
|
tooth
|
number of teeth(pcs)
|
L*
|
a*
|
b*
|
Men
|
right central incisor
|
88
|
72.52 ±4.11
|
-0.63 ±0.45
|
14.68± 2.02
|
|
right lateral incisors
|
88
|
69.15± 4.62
|
0.03±0.76
|
18.33±2.67
|
|
right canine
|
88
|
64.05±4.21
|
1.18±0.73
|
23.72±2.99
|
|
left central incisor
|
88
|
73.18±6.22
|
-0.48±0.33
|
14.92±3.29
|
|
left lateral incisors
|
88
|
69.59±4.7
|
0.22±0.56
|
17.94±3.80
|
|
left canine
|
88
|
65.70±4.10
|
1.52±0.62
|
23.31±3.53
|
Women
|
right central incisor
|
72
|
72.74±4.6
|
-0.45±0.31
|
14.53±3.43
|
|
right lateral incisors
|
72
|
69.86±4.84
|
0.16±0.56
|
18.03±3.98
|
|
right canine
|
72
|
66.59±4.21
|
1.43±0.53
|
23.03±3.41
|
|
left central incisor
|
72
|
73.26±4.47
|
-0.53±0.32
|
14.41±3.37
|
|
left lateral incisors
|
72
|
69.95±4.73
|
0.24±0.55
|
19.92±4.41
|
|
left canine
|
72
|
65.96±4.04
|
1.40±0.51
|
24.20±2.98
|
3.3 Left-right symmetrical interdental chromaticity values
The L*, a*, b* chromaticity values of the left and right symmetrical teeth with the same name were analyzed by paired t-test, and the results are shown in Table 4. There was no significant difference in the L*, a*, b* chromaticity values of the left and right symmetrical teeth with the same name (P > 0.05). Obtain the chromaticity difference (ΔL*, Δa*, Δb*) of the corresponding chromaticity values of the tooth with the same name, and obtain the chromaticity value of the left-right symmetrical tooth with the same name ΔE < 0.9, it can be considered that the color difference is not recognized by the human eye and cannot be recognized by the human eye. The difference in chromaticity between the left and right teeth with the same name.
Table 4 Statistics of chromaticity difference of chromaticity values of left-right symmetrical teeth with the same name
tooth
|
ΔL*
|
Δa*
|
Δb*
|
central incisor
|
0.73
|
0.06
|
0.1
|
lateral incisors
|
0.86
|
0.1
|
0.45
|
canine
|
0.86
|
0.09
|
0.14
|
3.4 Comparison of chromaticity values of different tooth positions
The mean ± standard deviation(`x±s) description, variance analysis, and paired t-test analysis of the chromaticity values of different tooth positions are shown in Table 5. There was no significant difference in the chromaticity values of the left and right symmetrical teeth with the same name (P > 0.05). Among them, 1) The order of lightness L* value is central incisor>lateral incisor>canine, the order of chroma a* value is: canine>lateral incisor>central incisor, the size of chroma b* value The order is: canine>lateral incisor>central incisor.
Table 5 Comparison of chromaticity values of each tooth position (x̄±s)
tooth
|
number of teeth(pcs)
|
L*
|
a*
|
b*
|
central incisor
|
320
|
73.02±4.41 #*
|
-0.54±0.35 #*
|
14.50±3.23#*
|
lateral incisor
|
320
|
69.96±4.70 #
|
0.22±0.63 #
|
18.60±3.94 #
|
canine
|
320
|
65.14±4.21 *
|
1.40±0.62 *
|
23.64±3.30 *
|
Compared with the same group of middle canines, #P < 0.05, compared with the same group of lateral incisors, *P < 0.05
3.5 Comparison of chromaticity values of the same tooth position in different age groups
The mean ± standard deviation (`x±s)description, variance analysis, and paired t-test analysis results of chromaticity values L*, a*, b* at different ages are shown in Table 6. L* value between different age groups: L* value of central incisors were significantly different (P<0.05), L* value of lateral incisors: there was no statistical difference between the 20-year-old group and the 30-year-old group, and between the 30-year-old group and the 40-year-old group, and there were statistical differences in the other age groups (P<0.05), L* value of canine group: there is a statistical difference between the 20-year-old group and the 30-year-old group (P<0.05), and there is no statistical difference between the other age groups. A* value between different age groups: The a* value of central incisors: 20-year-old group and 40-year-old group, 20-year-old group and 50-year-old group were statistically different (P<0.05), and there was no statistical difference between the other age groups, The a* value of lateral incisors: there was no statistical difference between each age group, a* value of canine teeth: there was a statistical difference between the 20-year-old group and the 50-year-old group (P<0.05), and the other age groups were compared in pairs no statistical difference. B* value between different age groups: The b* value of central incisors: the 20-year-old group was significantly different from other groups (P<0.05), and there was no statistical difference between the other age groups, The b* value of lateral incisors: there are statistical differences between the 20-year-old group and the 40-year-old group, the 20-year-old group and the 50-year-old group (P<0.05), and there is no statistical difference between the other age groups, And canine b* value: there were statistical differences between the 20-year-old group and the 50-year-old group, the 30-year-old group and the 50-year-old group (P<0.05), and there was no statistical difference between the other age groups.
Table 6 Comparison of chromaticity values for each age group
Age group(years)
|
tooth
|
number of teeth(pcs)
|
L*
|
a*
|
b*
|
|
central incisor
|
76
|
77.45±2.65*&
|
-0.51±0.60&
|
13.19±2.69*&
|
20~29
|
lateral incisor
|
73.23±2.83&
|
0.42±0.68
|
17.53±3.12&
|
|
canine
|
68.30±2.69&
|
1.67±0.63
|
23.18±2.96
|
|
central incisor
|
|
75.81±2.55#&
|
-0.68±0.66
|
14.17±2.57#
|
30~39
|
lateral incisor
|
84
|
71.62±8.48
|
0.37±0.58
|
18.69±2.57
|
|
canine
|
|
67.41±3.13&
|
1.59±0.65
|
23.75±3.17
|
|
central incisor
|
|
74.59±3.02#*
|
-0.75±0.65#
|
14.31±2.81#
|
40~49
|
lateral incisor
|
82
|
69.49±3.36#
|
0.35±0.47
|
19.19±2.87#
|
|
canine
|
|
64.20±3.27#*
|
1.44±0.63*
|
24.10±3.04
|
|
central incisor
|
|
72.63±3.01#*&
|
-0.83±0.72#
|
14.53±2.58#
|
50~59
|
lateral incisor
|
78
|
67.77±2.97#*&
|
0.30±0.75
|
19.38±3.21#
|
|
canine
|
|
62.45±2.87#*&
|
1.33±0.68#
|
24.48±2.55#*
|
Compared with the same tooth position 20-29 years old, #P < 0.05, compared with the same tooth position 30-39 years old, *P < 0.05, compared with the same tooth position 40-49 years old, &P < 0.05
3.6 Mean distribution of different tooth positions in different age groups
The mean distribution of L* values in different tooth positions in different age groups is shown in Figure 3. It can be seen that the L* value tends to decrease with the increase of age. The L* value represents the lightness, indicating that the younger the age, the higher the lightness. As age increases, the value of lightness decreases, and the color develops from white to black. No matter at which age, the L* value decreases from the central incisor to the distal end of the dental arch to the canine, indicating that from the central incisor to the distal end of the dental arch, The lightness gradually decreases from end to canine.
The mean distribution of a* values for different tooth positions in different age groups is shown in Figure 4. It can be seen that the a* value tends to decrease with age. The a* value represents the chroma, representing red and green, and −a*~ a* represents the hue from green to red. With the increase of age, the color develops from red to green. At the same time, no matter at which age, the a* value increases from the central incisor to the distal end of the dental arch to the canine, indicating that from the central incisor to the distal end of the dental arch to the canine Canine chroma develops towards red. With the increase of age, the color develops from red to green. At the same time, no matter at which age, the a* value increases from the central incisor to the distal end of the dental arch to the canine, indicating that from the central incisor to the distal end of the dental arch to the canine Canine chroma develops towards red.
The mean distribution of b* values for different tooth positions in different age groups is shown in Figure 5. It can be seen that the b* value tends to increase with age. The b* value represents the chroma, representing yellow and blue, and −b*~b represents the hue from blue to yellow, and the b value increases with age. , the color develops from blue to yellow, no matter at which age the b* value increases from the central incisor to the distal end of the dental arch to the canine, and the color develops from blue to yellow.