Histopathologic and SEM analysis of primary teeth with pulpectomy failure

Objective: The aim of this descriptive study was to identify the probable factors associated with pulpectomy failure of primary teeth through qualitative analysis by histopathology (HIST) and scanning electron microscopy (SEM). Methods: A longitudinal clinical investigation of the relative efficacy of pulpectomy was carried out with 66 children aged 3–8 years with irreversible inflammation or necrotic pulp. One hundred thirty primary teeth received instrumentation with Kerr files followed by irrigation with sodium hypochlorite and saline solution, then filled with zinc-oxide-and-eugenol (ZOE) paste. Results: At 18 months' follow-up, 86.1% (112) of the teeth were considered to have been successfully treated. Of the 18 teeth extracted due to treatment failure, 8 presented sufficiently undamaged roots to be randomly selected for analysis. Four teeth were chosen for HIST and four were analyzed in a SEM. Necrotic tissue and chronic inflammatory cells were observed in all specimens submitted to HIST analysis. Two specimens had root canal bacteria. Another common finding was external radicular resorption associated with Howship's lacunae. In SEM analysis, apical and furcation areas were heavily infected, and microorganisms were present in all specimens. Howship's lacunae were commonly observed on radicular apical surfaces. Conclusion: The findings of this investigation suggest that the main factors responsible for pulpectomy failure were technique limitations associated with the morphological irregularities created by external and inflammatory resorption.