• Sittidej Nincharoen

Objective The aim of this descriptive study was to determine the relationship between the width of maxillary anterior teeth, the interalar width and inner canthal distance. The present study was conducted to determine whether the interalar width and inner canthal distance could be used us a guide for selection of proper width of maxillary anterior artificial denture teeth. Since ethnicities of the population studied in the past were Caucasians and Arabians, the present study would like to investigate if this relationship can be suggested in Thai Population or not.

Materials and methods A total of 303 Thai subjects, 141 men and 162 women ranging in age from 18 to 71 years (mean age 35.2 + 13 years), were randomly selected from the outpatient dental clinic of Bangkok Metropolitan Administration General Hospital, Bangkok Metropolitan Administration. All subjects had maxillary anterior teeth present with no proximal caries, restorations or severe attrition and never had orthodontic treatment. All subjects had to be free from congential anomaly, orbital disease, trauma of facial surgery and diastema. The external width of the alae of the nose was measured at the widest point to determine the mean interalar width (MIAW). The mean inner canthal distance (MiCD) was measured from medial angle to medial angle of the palpebral fissures of each eye. The mean combined width of the 6 maxillary anterior teeth (M6W) was determined with their mesiodistal width of each between their interproximal contact points. Each factors were measured 3 times for each subject, and the values were calculated for average value standard deviation. One examiner performed all measurements and recorded all the data to ensure the reliability. Pearson correlation coefficients were calculated to determine the relationship between the widths of maxillary anterior teeth, interalar width and inner canthal distance (α = 0.05) by SPSS 11.5 for Windows.

Result The mean interalar width, the mean inner canthal distance and the mean of maxillary anterior teeth widths was 41.32 + 3.86 mm., 34.81 + 2.78 mm. and 46.86 + 2.49 mm. respectively. The correlation between the widths of maxillary anterior teeth and interalar width was slight and statistically significant (r = 0.271, p < 0.001). The widths of maxillary anterior teeth and inner canthal distance were related slightly, but significantly  (r = 0.109, p < 0.042). The interalar width was related slightly with inner canthal distance, but statistically significant  (r = 0.153, p < 0.008). Although the Pearson’s correlation coefficients were relatively small, a significant relationship existed between interalar width, inner canthal distance and the widths of maxillary anterior teeth. The maxillary anterior teeth widths was found to be higher correlated with interalar width than inner canthal distance  (p < 0.001). The only factor that can be used to predict the widths of maxillary anterior theeth by linear regression was the interalar width.

Conclusion It was found that these relationships can be used in Thai population but the interalar width has more relationship with the width of maxillary anterior teeth than the inner canthal distance. Although the Pearson correlation coefficients were relatively small, a significant relationship existed between interalar width, inner canthal distance and the widths of maxillary anterior teeth (p < 0.001). Although these two measurements are used to predict the width of maxillary anterior teeth, several anatomic measurements should be considered to aid in anterior teeth selection.

(CU Dent J. 2006;29:33-43)