Infraoccluded primary molars: New findings from the last 10 years - A systematic review

This review summarises recent findings from the past decade on infraoccluded primary molars, focusing on diagnosis, aetiology, prevalence, associated findings and clinical consequences, and to compare these with earlier literature to support improved clinical management.

A systematic literature search was conducted according to PRISMA guidelines, evaluating MEDLINE (PubMed), Cochrane Library, Web of Science, and Embase from 2014 to 2025. Randomized controlled trials (RCT), non-randomized studies of interventions (NRSI), cohort studies, case-control studies and cross-sectional studies published in English and German were included. Case series, case reports, expert opinions and commentaries were excluded.

Of 2816 publications identified, 30 met the inclusion criteria after screening and full-text review. These studies addressed prevalence (n = 17), retained molars (n = 4), retained molars without successors (n = 5), aetiology (n = 1), diagnosis (n = 1), mandibular growth impact (n = 1), and interventions (n = 1).

Current evidence provides new insights into the aetiology and clinical management of infraoccluded primary molars. Genetic factors, particularly those related to epithelial development and inflammatory signalling pathways, are increasingly recognised. Conservative treatment approaches have gained traction, emphasizing alveolar preservation over orthodontic considerations of craniofacial growth. Most cases are mild and occur unilaterally in mandibular first primary molars. Early-onset infraocclusion is linked to a less favourable prognosis. Root resorption shows age-related variability. However, conflicting evidence exists regarding the association of infraocclusion with root resorption, especially in cases of tooth agenesis, and its correlation with mandibular growth rotation. Additionally, prevalence data remain inconsistent due to heterogenous classification, underscoring the need for further research.