Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry detecting NOS in healthy and chronically inflamed pulp.

The aim of this study was to examine the expression of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity in human dental pulps and determine whether there are changes of the activity in chronically inflamed pulp tissue. Nineteen pulps with clinical diagnosis of chronic pulpitis were collected during endodontic treatment. The healthy controls were obtained from teeth extracted for orthodontic therapy. The clinical diagnosis was confirmed by histological analysis. Healthy pulps showed stratified odontoblasts in peripheral parts, while in central area there was normal connective tissue. Chronically inflamed pulps showed less expressed stratification of odontoblasts and infiltration of lymphocytes, polymorphonuclear leukocytes, plasma cells and mastocytes. NADPH-d granular reactivity was assessed semi quantitatively under the light microscope by a single observer and scored on an intensity scale from negative reaction to very strong reaction. In healthy human pulps, NADPH-d activity was strong to very strong in odontoblastic layer. Endothelial cells and Schwann cells showed strong NADPH-d reactivity, while the other parts of central area were weakly positive. Similar distribution of reactivity was expressed also in chronically inflamed pulp; moderate to strong reaction was observed in stromal area as result of positive reaction in inflammatory cells and endothelial cells of abundant newly formed capillaries.