Relationship between the Mesiodistal Width of Maxillary Central Incisor and Interpupillary Distance

Estimating the width of maxillary central incisor may be difficult when an artificial tooth is selected for edentulous patients. One of the ways to choose a good size for this tooth is using extra-oral landmarks in face. This study examined the relationship between mesiodistal (MD) width of maxillary central incisor and interpupillary distance (IPD) which is a stable landmark in lifetime. In this descriptive cross sectional study, 100 Iranian subjects (50 males and 50 females, mean age 23±6.3 years) without ocular and dental deformities were selected. The MD width of upper central incisor and IPD were measured three times for each subject using Boley Gauge with 0.1 mm accuracy and then, the mean values were calculated. A mathematic equation to evaluate correlation between MD width of upper central incisor and IPD was calculated and then examined in the other 20 subjects (10 males and 10 females, mean age 24.8±1.56 years) by statistically comparing the difference between calculated and real size of tooth with paired t-test. In the first stage, these results were obtained: the mean MD width of maxillary central incisor was 8.6±0.4mm and the mean IPD was 62.1±2.8mm. The correlation coefficient between these two parameters was r=0.446 (P<0.05). The calculated equations for this relationship were: (Y=0.15x–0.0002x² in men and Y=0.22x–0.0014x² in women, “y” represents MD width of maxillary central incisor and “x” represents IPD). In the second stage, these equations were applicable in 90% of subjects (18 from 20 subjects) with 0.5mm of accuracy. IPD is a good landmark for estimating MD width of maxillary central incisor in edentulous patients.