Impacted permanent first and second molars and failure of eruption: A comprehensive review for the orthodontic practitioner

This article provides a comprehensive review of the current literature on impacted first and second permanent molars, focusing on etiology, diagnosis and orthodontic management. Due to the extremely limited orthodontic possibilities in primary failure of eruption cases, the present review mainly focuses on impacted molars due to mechanical obstruction in the path of eruption, abnormal orientation and failure of eruption due to ankylosis. Clinical cases are used to illustrate management of ankylosed, ectopic first molars and mesioangulated impacted second molars, aiming to assist clinicians in deciding on differential diagnosis, case selection, optimal timing and mechanotherapy of these challenging conditions.