Decision-Making for Space Maintenance After the Premature Loss of Primary First Molars: A Clinically Oriented Narrative Review

The aim of this narrative review is to critically integrate the available evidence on space changes following the premature loss of primary first molars and to develop a clinically orientated, evidence-based decision-making framework for space maintenance. A clinically focused narrative review was conducted using PubMed and Google Scholar databases. Studies that met the eligibility criteria and were published in the English language between January 1998 and December 2025 were included. Fourteen primary studies and six systematic reviews were selected based on PECO (population, exposure, control, and outcome) criteria. Evidence was synthesized narratively, rather than through a quantitative meta-analysis, due to substantial heterogeneity. Eruption and stable intercuspation of the first permanent molar, as well as a leptoprosopic facial growth pattern, consistently emerged as independent predictors of clinically relevant space loss. In contrast, archetype, molar relationship, time elapsed since extraction, and crowding functioned primarily as modifying factors. Clinical decision-making should be individualized using a structured, risk-based framework that integrates biological and occlusal determinants rather than relying solely on tooth loss.