Histopathologic evaluation of three ultraviolet-activated composite resins on monkey pulps

The pulpal responses of three ultraviolet-activated composite resins, Nuva-Fil, Experimental UV No. 1 and Experimental UV No. 2, were tested on adult monkey teeth using silicate and zinc oxide eugenol (ZOE) as positive and negative controls. All materials were placed in Class V cavity preparations in Rhesus monkey teeth using approximately 48 anterior and 63 posterior teeth of both the maxillary and mandibular arches. A total of 111 teeth were utilized and all materials were evaluated at 3 days, 5 and 8 weeks. Following left ventricular perfusion, the teeth were prepared for microscopic evaluation using routine histological procedures. The 3-day pulpal response of all the ultraviolet-activated composites was slight with some disruption and vacuolization in the odontoblastic layer and a slight inflammatory response. At 5 weeks there was a reduction of the inflammatory response and the formation of reparative dentin was noted for all ultraviolet composites. The 8-week pulp response was slight, characterized by a minimal inflammatory response adjacent to the zone of reparative dentin. Generally, ZOE produced the mildest response while silicate produced the most severe response at the three time intervals.