Abstract
Tooth fusion in the permanent dentition is exceedingly uncommon, particularly if involving a mandibular lateral incisor–canine pair. Bilateral fusion is even more rare. The present study describes a 27-year-old female who presented with severe maxillary anterior crowding and bilateral mandibular tooth fusion, which was complete on the right and incomplete on the left side. After discussion of alternative options, treatment comprised the extraction of both maxillary first premolars, conservative reduction of the right fused unit and a controlled 90° rotation of the left fused mandibular teeth, while applying a self-ligating fixed appliance system. Over 25 months of comprehensive orthodontic therapy, Class I molar and canine relationships were maintained, the mandibular midline was corrected, the maxillary incisors were uprighted and retracted, the mandibular incisor inclination was reduced, and overjet and overbite were normalised. At a three-year review, occlusal stability, periodontal health and patient satisfaction were upheld. This proof-of-concept demonstrates that rotational mechanics can effectively create space and harmonise tooth form in cases of rare fusion anomalies without compromising pulp vitality or periodontal integrity and further, highlights the need for larger cohort studies to confirm long-term predictability.