LAUSR

BACKGROUND It is rare for a first permanent molar (FPM) to temporarily exhibit clinical features of failure of eruption, followed by regeneration of full eruptive capacity 5 years later. Indeterminate failure of eruption (IFE) is a diagnosis of exclusion where the distinction between primary failure of eruption (PFE) and mechanical failure of eruption (MFE) is unclear, including patients too young to specify. CASE REPORT An 11-year-old girl attended the orthodontic clinic at Mid Yorkshire Hospitals NHS Trust regarding an unerupted lower right FPM. Her medical and dental trauma history was unremarkable. She presented with a Class II division 2 malocclusion in the mixed dentition, with all other FPMs fully erupted. CONCLUSION This report documents that an unerupted FPM in an 11-year-old patient may still have the eruptive potential to become functional within the dentition. The period spent monitoring the FPM's outcome prior to surgical intervention has avoided an operation under general anaesthetic and potentially unnecessary orthodontic treatment, as the tooth subsequently erupted without treatment.