An Assessment of the Accuracy of Recurring Esthetic Dental Proportion: An In Vivo Comparative Analysis of Maxillary Anterior Teeth Proportion With Chu's Gauge and Custom-Made Calipers

Abstract

Smile designing, in harmony with nature, has always been a challenge in dentistry. Several theories have been proposed in the past with a view to replicate an esthetic smile. One such method proposed by Dr. Chu involves using the recurring esthetic dental (RED) proportion. He designed a scale for calculating the average values for the height and width of upper anterior teeth for a specified population. However, whether this average is valid for other populations has not been verified. Hence, this study was conducted to evaluate if Chu's gauge value agrees with the dimension of anterior teeth in the South Indian population. The study involved 362 subjects whose anterior teeth dimension was assessed using Chu's gauge and a custom-made caliper. The proportion of the population whose dimension aligns with the average values on Chu's gauge was evaluated. The results showed that in the cohort, 39% had their central incisor dimension coinciding with the red band of Chu's esthetic scale, 10% had their lateral incisor coinciding with the blue band of Chu's esthetic scale, and 6.4% of the subjects had their canine dimension coinciding with the yellow band of Chu's esthetic scale.

Keywords: chu's esthetic gauge; golden proportion; smile engineering; smile esthetics; teeth proportion.

Figure 1. Description of the Chu’s gauge

The Chu’s gauge has a T-bar tip (for normally aligned teeth) and an in-line tip (for crowded teeth). The T-bar tip has a horizontal arm, vertical arm, and incisal guide. The measurements on the horizontal arm range from 5.5 mm to 10.5 mm, and on the vertical arm, they range from 7 mm to 13.5 mm, which corresponds to the minimum and maximum width and height of the maxillary anterior. The average width and length for lateral incisors correspond to the blue band (6.5 mm/8.5 mm), that of the canine to the intermediate yellow band (7.5 mm/9.5 mm), and that of the central to the red band (8.5 mm/11 mm)

Figure 2. The variation between the color coding on the Chu’s gauge and the dimension of central incisors

Figure 3. The variation between the color coding on the Chu’s gauge and the dimension of lateral incisors

Figure 4. The variation between the color coding on the Chu’s gauge and the dimension of the canine

Figure 5. The measurement of central incisor width by using the custom-made caliper