Arrested Eruption of 22 Permanent Molars: Etiological Considerations

Background and objectives: The purpose is to demonstrate how histochemical analyses can contribute to the understanding of the aetiology behind arrest in the normal eruption process of permanent molars. Methods: Histochemical analyses: 22 permanent molars diagnosed clinically or radiographically with arrested eruption and subsequently extracted or surgically removed, were analysed histochemically. After fixation in formalin followed by decalcification, paraffin embedding, sectioning and later staining with haematoxylin-eosin and alcian blue, according to the van Gieson method, the sections underwent microscopy and photography. The sectioning of each molar allowed only microscopic observations in the cutting plane. Results: The periodontal membrane was abnormal in all cases. The dominant impression of the roots was the presence of enormous or severe layers of hard tissue (hypercementosis). Conclusion: The layering of appositional bone on the root surfaces of the arrested molars might explain the arrest, also in cases where the space was sufficient for eruption. The arrest in eruption was associated with lack in alveolar bone apposition.