Original Articles
Color and translucency of in vivo natural central incisors,☆☆

Presented at the 76th IADR general session, Nice, France, June 1998. Presented at the annual meeting of the Japan Prosthodontic Society, September 1998.
https://doi.org/10.1016/S0022-3913(00)70036-9Get rights and content

Abstract

Statement of problem: The range of shades in shade guides is not consistent with natural teeth, and there is no information on the color and translucency of the natural tooth for all age groups. Therefore, it is important to obtain a database of the characteristics of the natural tooth from a wide age group. Purpose: This study obtained information on color and translucency of natural teeth for all age groups, and attempted to clarify the difference of the color and translucency between natural teeth and VITA Lumin Vacuum shade guide. Material and methods: Natural central incisors of 87 subjects (42 men and 45 women; age range from 13 to 84 years) and 16 shades of VITA Lumin Vacuum shade guide were evaluated. Color and translucency of 5 sites, each 1.0 mm in diameter, on the surfaces of individual teeth were measured for L*, a*, and b*, using a color computer according to CIELAB color spaces. Results: At the center site, negative correlation was found between age and L*, with positive correlation between age and b*. Both a* and b* of the natural tooth increased when moving in the direction of the cervical site, but translucency decreased in the direction of the root. The a* value for the natural tooth was significantly higher than those for VITA Lumin Vacuum shade guide. Conclusion: This study found that the older the subject, the darker and more yellow the color at the center site of the natural tooth. Both reddish and yellowish colors of natural teeth tend to increase from the incisal to cervical, whereas translucency decreases. Red-green chromaticity of VITA Lumin Vacuum shade guide was not distributed to cover the natural tooth. (J Prosthet Dent 2000;83:418-23.)

Section snippets

Material and methods

Eighty-seven Japanese subjects (42 men and 45 women) were randomly selected for this study. They ranged in age from 13 to 84 years old and were classified into 6 age groups for each sex: under 19, 20 to 29, 30 to 39, 40 to 49, 50 to 59, and more than 60 years of age (Table I).

. Number of subjects and composition of ages

Age group (y)MaleFemaleTotal
Under 199 (13.9)7 (18.9)16 (16.1)
20 to 299 (26.7)8 (22.9)17 (24.9)
30 to 398 (35.0)10 (35.1)18 (35.1)
40 to 497 (44.3)7 (47.4)14 (45.9)
50 to 596 (54.2)4

Results

Table II shows the correlation coefficient between L*, a*, b*, TP, and age groups at each site. The simple linear regression analyses for L* revealed a significant negative correlation with age at the center, center-cervical, and cervical sites, but no such correlation was found at the incisal and incisal-center sites. For a*, no significant correlation was observed with age, except at the incisal site, where a significant positive correlation was found. For b*, a significant positive

Discussion

In this study, lightness (L*) at the center, center-cervical, and cervical sites decreased linearly with age (Table II), which is consistent with the findings of Goodkind et al.19 It is speculated that natural teeth darken after the age of approximately 35 years by the formation of secondary dentine.19 However, in our study, the decrease in lightness was not found at 2 neighboring incisal sites. This can be explained by the effects of the black cloth as a background through the translucent

Conclusion

The color and translucency of individual teeth and shade tabs were measured using a novel color computer system. Within the limits of this study, the following conclusions were drawn:

  • 1.

    Natural tooth color showed a significant decrease in lightness at the center to cervical site and increase in yellowness at all 5 sites with advancing age. The color of natural teeth also showed an increase in redness at the incisal site and a decrease in translucency in the region near the incisal site with age,

Acknowledgements

With grateful thanks to Dr M. Analoui (Indiana University, Indiana), and Mr R. Gilmore (AstraZeneca, UK) for their kind assistance and syntax for valuable comments on the manuscript.

References (20)

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Copyright © 2000 by The Editorial Council of The Journal of Prosthetic Dentistry.

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