An atypical presentation of mechanical failure of eruption of a mandibular permanent molar: diagnosis and treatment case report.

BACKGROUND

Failure of eruption of mandibular permanent molars occurs infrequently but is a difficult clinical problem. It can be due to local or systemic factors or failure of the eruption process. Primary failure of eruption (PFE) is a rare condition that can result in severe posterior open bite, requires complex treatment strategies and has unfavourable outcomes. Mechanical failure of eruption (MFE) is more unusual but can respond positively to treatment. Differentiating between the two is crucial in making the correct diagnosis and managing the case successfully.

CASE REPORT

A 10-year-old girl presented with a partially erupted mandibular right first permanent molar, 46. She had no relevant medical or dental history and no family history of tooth eruption failure.

TREATMENT

46 was monitored for 6 months to allow spontaneous eruption. Local and systemic factors were eliminated. Progress radiographs and longitudinal clinical data were collected. Attempted eruption of 46 was completed by surgical luxation and elevation by orthodontic force.

FOLLOW-UP: Surgical luxation and elevation of 46 was repeated with the removal of the mandibular right second permanent molar, 47, which was mechanically obstructing the eruption of 46. With continued orthodontic force the tooth was righted up and brought into occlusion with no complication of ankylosis. The mandibular right third molar continues to erupt and migrate mesially. The patient now exhibits a bilateral functioning posterior bite three years after the treatment was commenced.

CONCLUSION

Through a combination of sequential monitoring with treatment including surgical luxation and orthodontic force, a therapeutic diagnosis of MFE was made. The appropriate treatment was carried out and the tooth erupted into occlusion.