Canine Substitution for Missing Maxillary Lateral Incisors: the Influence of Canine Morphology, Size, and Shade on Perceptions of Smile Attractiveness

Introduction: This study was conducted to determine whether variations in the morphology, size, or shade of maxillary canines would influence perceptions of smile attractiveness in patients with canines substituted for missing maxillary lateral incisors.

Methods: A smiling photograph of a hypodontia patient who had had orthodontic space closure with maxillary canines replacing the lateral incisors was digitally modified to create a bilaterally symmetrical image. Four groups of images were created, digitally altering canine gingival height, crown tip height, canine width, and canine shade. Three groups of judges (40 orthodontists, 40 dentists, and 40 laypeople) ranked the images for smile attractiveness, also scoring the most and the least attractive of each of the 4 groups, and the most and least attractive of all images.

Results: Canine gingival height was the most attractive 0.5 mm below the gingival margin of the maxillary central incisor and progressively less attractive with increasing gingival height. Increasing canine width, increased canine tip height, and pointed canines were perceived to be unattractive. Brighter than normal shades of canines were preferred to darker shades. Narrow canine crowns were most frequently ranked as the most attractive overall, 1.5 mm narrower was preferred by the orthodontists and dentists, and 3.0 mm narrower was preferred by the laypeople. All 3 groups ranked the darkest image, 20 times darker than the original, most frequently as the least attractive image overall. There was good general agreement between orthodontists, dentists, and laypeople for all 4 parameters of smile attractiveness, although laypeople demonstrated greater intragroup variations.

Conclusions: The morphology, size, and shade of the maxillary canine in patients having orthodontic space closure and lateral incisor substitution can have a marked effect on perceived smile attractiveness.