Extraction of first primary molars and significance of space loss: a systematic review and meta-analysis

To quantify space loss following premature extraction of primary first molars (Ds) over a follow-up period of at least six months and evaluate its clinical implications. A systematic search of PubMed, Cochrane Library, LILACS, Web of Science, and Embase was conducted. Only longitudinal split-mouth cohort studies were included. The primary outcome was the amount of space loss in the extraction region, measured against the contralateral control side. 7 studies were included, comprising 141 children for maxillary analysis and 171 children for mandibular analysis. Meta-analysis for space loss revealed a mean difference (MD) of -0.52 mm (95% CI: -0.79 to -0.26; p < 0.001) in the maxilla after 9–12 months, and − 1.78 mm (95% CI: -2.09 to -1.47; p < 0.001) in the mandible after 8–9 months. Premature loss of Ds in children aged 6–9 years results in space loss of -0.52 mm in the maxilla and − 1.78 mm in the mandible. Space maintainers are indicated following mandibular extractions, while maxillary cases may not require routine intervention.