Distribution of space loss after premature extraction of primary molars

With little evidence and controversial guidelines on space maintainers, this cross-sectional population-based study aimed to analyze the prevalence and distribution of space loss after premature extraction of primary molars and the potential effect for space maintainers.

Within the compulsory dental examinations in all primary schools in Greifswald, Germany, 6- to 12-year-old children were screened for premature loss of primary molars. The mesiodistal dimension at the site of extraction and the contralateral tooth were measured with Zürich calipers by two calibrated examiners.

Out of 1,596 students, 190 (11.9%) exhibited early loss of primary molars (47.9% females, mean age 8.73 ± 1.02 years). In total, 152 of 291 missing molars that were lost unilaterally were suitable for comparison with the intact side. Only 26 students had a space maintainer (8.9%). There was a statistically significant difference in space loss after premature extraction of primary molars with and without space maintainer (mean 0.59 ± 0.94 mm vs 1.66 ± 1.66 mm, respectively, P = .037). This was especially true for second primary molars (2.62 ± 1.93 mm; first molars 1.17 ± 1.30 mm; P .001). Space loss in the maxilla (1.75 ± 1.68 mm) was slightly higher than in the mandible (1.40 ± 1.58 mm, P = .187). In total, 53.3% of the children exhibited minimal space loss (≤ 1 mm), and 22.4% experienced 2.5 to 7.0 mm space loss.

More than 10% of a low caries-risk population exhibited premature extraction of at least one primary molar. Space loss was greater in the region of second primary molars, while space maintainers significantly reduced space loss. Due to the complexity and variation of space loss, decision making on space maintainers should be individualized.