Background: The aim of this study was to assess the size of upper incisors and canines in patients with gaps in the upper dental arch, especially medium gap between upper central incisors.

Materials and methods: Diagnostic orthodontic models of 30 adult patients with full permanent dentition with diastema in the upper arch were studied. Patients with severe malocclusion, missing teeth and periodontal disease were excluded. Width-to-length (W/L) ratio of the clinical crown of the central, lateral incisors and canines for both sides was measured. Together 180 teeth were tested. The results were compared with the values indicated by Sterrett et al.

Results: In all patients, the clinical crowns of central incisors were symmetrical. In most cases, a higher W/L ratio was found, which indicates that the clinical crowns of medial incisors were too broad in relation to the length. Lateral incisors: In most cases, the ratio was the same for the right and the left side; however, a few patients had asymmetry of lateral incisors. Most of the lateral incisors had higher W/L ratios, which means that the teeth were wider than they were long; some had reduced ratios and only in one case the ratio was proper. Canines were also asymmetrical, and none of the canine exhibited perfect proportions. The vast majority showed increased W/L ratio of the clinical crown. In several cases, the W/L ratio was decreased.

Conclusions: Patients with gaps between the teeth have abnormal W/L ratio of the clinical crowns of the upper front teeth. The values were increased in the majority of cases, which indicates that the front teeth were wider than they were long in patients with gaps. Moreover, despite the disturbed W/L proportions, central incisors remained symmetrical. In contrast, lateral incisors and canines more often exhibited asymmetries.