Inner-Canthal Distance as a Guide for Replacement of Anterior Teeth

Objective: This study investigated the relationship of the inner-canthal distance to the maxillary anterior teeth in fully dentate patients. Methods: Standardised full face photographs of 50 subjects viewed from the front i). with relaxed facial muscles, and ii). smiling to show the anterior teeth, were recorded with digital camera. Using image analyser software (Leica Qwin Lite Vers. 2, Leica Microsystems Imaging Solutions, Cambridge, U.K.) the images were used to determine: the interpupillary distance (IPD), the inner canthal distance (ICD) and the interalar distance (IAD). Maxillary casts of these subjects were also examined to determine the distance joining the tips of the maxillary canines in a straight line (ICS), distance between the incisive papilla and the labial surface of the maxillary central incisors (IPL), and the curved intercanine-tip distances (ICC). ICS measurements were made directly on the casts using digital callipers (Mitutoyo), and a dental tape was used to measure ICC. Using the Pythagoras theorem, the intercanine arc distance (ICA) could be calculated mathematically when ICS and IPL values were obtained, and compared to ICC. Results: There was no significant difference between ICD and ICS (P > 0.05). The mean ICD value was 34.4 ± 2.55 mm. The mean IPL was 10.1 ± 1.6mm, and the mean ICS was 35.0 ± 1.85 mm. The mean ICC was 44.04 ± 0.31 mm, while the mean ICA value was 42.09 ± 2.23 mm. There was no significant difference between the mean ICC and ICA values (P > 0.05). Conclusion: The results show that the inner canthal distance may be used as a guide in patients requiring replacement of the anterior teeth to achieve pleasing and aesthetic outcomes.