Teeth and gingival display in the premolar area during smiling in relation to gender and age

There is limited knowledge concerning tooth and gingival display in the maxillary premolar area during smiling. The purpose of this study was to investigate maxillary premolar and associated gingival display during smiling, and to reveal possible differences related to gender and age. The study consisted of 90 males and 113 females (mean age 38 years, s.d. = 13.83) receiving regular dental care. Two pictures of each subject, one with lips in maximum smile, and the other a retracted frontal view, were made. Clinical crown length, tooth and gingival display were measured for the left maxillary premolars. Central incisors and canines were used as controls. anova with Bonferroni post hoc multiple comparisons tests was used to assess any statistically significant impact of gender and age on tooth and gingival display, and determine differences among gender and age groups (at 5% significance level). Premolars were partially visible in more than 80% of the smiles, and displayed more than 65% of their clinical crown length during smiling. The least display (P < 0.001) was recorded for first and the greatest for second premolars. Tooth display was greater in females, but statistically significant only in central incisors (P < 0.05). No significant differences were revealed between age subgroups. Gingival display was greater for premolars compared with both central incisors (P < 0.001) and canines (P < 0.05). Displayed gingiva was found in first and second premolars in 44 and 49% of subjects, respectively. More gingival display was recorded in females and in younger subjects.