Figure 1. NAC protects the pulp cells from undergoing cell death and growth inhibition after composite restorations in vivo. (A) Nine 8-week-old male rats were divided into 3 groups where (A) no restoration, (B) composite restoration, or (C) composite restoration with NAC was applied. Five hrs after restoration, the teeth were split open, the pulp tissue was removed, and the pulp cells were prepared as described in MATERIALS & METHODS. Dental pulp stromal cells from each group were cultured in media with a combination of β-glycerophosphate (10 mM) and ascorbic acid (50 µg/mL) for 4 wks, after which photographs were taken by means of an inverted microscope (mag. 20X). The results are representative of 3 independent experiments. (B) Rat dental pulp stromal cells were prepared as indicated in Fig. 1A. Five wks after the culture of dental pulp stromal cells, they were trypsinized, and the cell numbers were determined for each group. The results are representative of 3 independent experiments. The cells were counted in triplicate and presented as mean ± standard deviation. p 0.001 for differences between the composite- and ‘composite with NAC’-treated groups. (C) Rat dental pulp stromal cells were prepared as indicated in Fig. 1A. After 5 wks of culture, dental pulp stromal cells were stained, and the levels of alkaline phosphatase staining were determined for each group. The results are representative of 3 independent experiments. Panel C of this Fig. appears in color in the online version.