Date of Completion


Embargo Period



John Agar; Patchanee Rungruanganut; Douglas Adams

Field of Study

Dental Science


Master of Dental Science

Open Access

Open Access




It has long been taught that the basic shade (hue) of the patient can be taken from the canine (i.e. that tooth thought to have the highest chroma of a particular hue) and then that hue can be applied to other anterior teeth but at a lower chroma. However, this concept does not appear to derive from published measurements or observations. This study documented the color relationship between in vivo maxillary central incisors and canines to examine: (1) whether they share the same hue, but have different chromas (as commonly taught); and, (2) whether color differences (∆E values) change as a function of age.

Materials and methods

The L*a*b* values and Vita Classic shades of the maxillary central incisor and canine (62 subjects) were determined using a handheld spectrophotometer. Linear regression analysis and t-tests were used to describe the relationships of the L*a*b* values of these teeth within each patient and as a function of age.


Linear regression analysis with a 95% confidence demonstrated a significant decrease in ∆E with age (p = 0.056). There was a significant age difference (p = 0.019) for the ∆E value between the central incisor and canine for those patients whose ∆E was greater than 3.3 (average age = 38.8) compared to patients with a ∆E less than 3.3(average age = 58.8) (t-test, p = 0.19). ∆C decreases significantly with age (p < 0.001). ∆H demonstrated a trend to decrease as a function of age (p = 0.2). ∆L remained the same over age (p = 0.21). The difference seen for all three color coordinates (hue, value and chroma) were due to a significant change in the central incisor while the canine remained constant with increasing age.

Major Advisor

Robert Kelly