Delayed healing of apical periodontitis lesions after root canal treatment: Report of two cases

Persistent periapical radiolucency after apparently adequate root canal treatment is often interpreted as post-treatment failure that requires non-surgical retreatment or surgery. However, radiographic persistence does not invariably represent ongoing apical periodontitis. This report describes two anterior teeth with large preoperative periapical radiolucencies that showed progressive reduction after nonsurgical root canal treatment, yet retained residual radiolucency for years. Cone-beam computed tomography disclosed internal, non-homogeneous high-density areas within the residual radiolucent regions. These high-density areas are compatible with intralesional mineralization and ongoing osseous remodeling rather than active infection. In one case, apical microsurgery was performed because the lesion was interpreted as treatment failure. Nevertheless, histology demonstrated uninflamed fibrous connective tissue with irregular mineralized material and absence of bacteria, contradicting an infectious diagnosis. Recognition of imaging patterns compatible with delayed healing may help prevent unnecessary interventions and supports