Unprepared root canal surface areas: causes, clinical implications, and therapeutic strategies.

Chemomechanical preparation is intended to clean, disinfect, and shape the root canal. This step is of utmost importance during treatment of infected teeth with apical periodontitis, because treatment outcome depends on how effectively the clinician eliminates bacteria, their products, and necrotic tissue that would serve as substrate for bacterial regrowth. Nonetheless, curvatures and complex internal anatomical variations of the root canal system can pose a high degree of difficulty in reaching these goals. In infected teeth, bacteria may persist not only in difficult-to-reach areas such as isthmuses, ramifications, dentinal tubules, and recesses from C-shaped or oval/flattened canals, but also in areas of the main canal wall that remain untouched by instruments. If bacteria withstand chemomechanical procedures, there is an augmented risk for post-treatment apical periodontitis. This article discloses the reasons why some areas remain unprepared by instruments and discusses strategies to circumvent this issue and enhance infection control during endodontic treatment/retreatment of teeth with apical periodontitis.

Pro-inflammatory and anti-inflammatory cytokine expression in post-treatment apical periodontitis.

OBJECTIVE: This study evaluated the expression of pro-inflammatory (IL-1ß, IL-6, IFN-γ and TNF-α) and anti-inflammatory (IL-4 and TGF-ß) cytokines in apical periodontitis lesions. Correlations between these cytokines and clinical and cone-beam computed tomographic (CBCT) data were also assessed. MATERIAL AND METHODS: Apical periodontitis lesions' data were obtained from 27 patients subjected to periradicular surgery. Specimens were processed for histopathologic and immunohistochemical analysis. Sections were evaluated according to the amount of positive staining for each antibody. Expression levels of the target mediators were compared with clinical and CBCT data. RESULTS: Twenty lesions were diagnosed as granuloma and 7 as cyst. In granulomas, IL-4 expression was significantly higher than IL-6 (p=0.001) and TNF-α (p=0.001). There was a significant relationship between high levels of TNF-α and lesions <5 mm (p=0.017). In cysts, IL-6 expression was significant lower than IL-4 (p=0.001) and IFN-γ (p=0.004). There was a significant relationship between high levels of TGF-ß and endodontic treatment performed ≤4 years before (p=0.045). In general, IL-4 was the most expressed mediator in both cysts and granulomas. CONCLUSIONS: There was a balance between the expression of pro-inflammatory and anti-inflammatory cytokines associated with the chronic periradicular inflammatory process. TNF-α and TGF-ß were related to some clinical and CBCT data.