Spaced dentition. An epidemiologic study.

This epidemiologic study deals with the incidence of spaced dentition in 1279 students between the ages of 12 and 18 years. The sample includes only those with a full complement of permanent teeth (third molars were not considered) and with no apparent etiological conditions that might lead to disruption of dental arch continuity. The sample was evenly divided by age and sex. Frequency of spaced dentition was high, occurring in 51.8% of males and in 45.5% of females. Prevalence was less in higher age groups, and the sexual dimorphism that was significant in the 14 YR-16 YR group was not found in the 16 YR-18 YR group. The mean number of spaces per subject was 6 +/- 4.3 for males and 5 +/- 3.7 for females, again displaying diminishing incidence with age and a concomitant absence of the sexual dimorphism in the highest age group. Spaces were found in both arches in 49.5% of the spaced dentitions, and in only the maxillary arch in 34.3%. Incidence of spacing in the mandibular arch alone was only 16.2%. In most subjects the spaces were distributed equally between the two quadrants of each arch. The most common sites and largest space widths in either dental arch were found between cuspids and the first bicuspids and between cuspids and lateral incisors.