Experimental Study Of Nano Calcium Phosphate Cement As Root Canal Filling Sealer

Objective: The aim of this study is to evaluate the basic experiments of a new material based on the nano Calcium Phosphate Cement (nano-CPC) before it is used clinically as a root canal filling sealer.Method:Part 1: Animal subjects were selected according to the criteria for medical materials recommended in ISO 10993 and GB/T 16886-1997. The root canal sealer was implanted into the subcutaneous tissue of seven rabbits. General and histopathological examinations of peripheral packed tissue of materials were performed at 4th week, 8th week, and 12th week, respectively. Part 2: The root canals of 45 freshly extracted single human teeth were prepared and then randomly divided into three groups, with 15 teeth in each group. All of them were examined with X-ray to assert that the angles of curvature of all the canals were below 10°. After cleaning and shaping, the teeth were obturated with ZoE, Cortisomol and nano-CPC, with lateral condensation techniques. Apical microleakage was determined using dye penetration with vacuum applied; the extents of dye penetration were measured. Part3: Six adult male beagle dogs were used in this study. In the group of acute periapical periodontitis, the 81 root canals from the three dogs were divided into four groups, with at least 18 in each group. After cleaning and shaping,apical of root canals was artificially stimulated. Root canals of three groups above were filling with the lateral condensation technique using one of three filling materials: ZoE, Cortisomol, nano-CPC, and gutta-percha. The other roots were control group. The three subjects were killed at 4th week, 8th week and 12th week respectively. The specimens were then prepared for histo-pathologic analysis. In the group of chronic periapical periodontitis, 24 root canals of the last three dogs were divided into four groups. Dog'periapical diseases were determined by x-ray film after 6 weeks. After cleaning and shaping, root canals of three groups above were filling with the lateral condensation technique using one of three filling materials: ZoE, Cortisomol, nano-CPC and gutta-percha, the last roots were control group. The subjects were killed after 12 weeks. Specimens were then prepared for histo-pathologic parameters.Results Part1: The results suggest that the nano-CPC had no apparent inflammatory reaction in implanting subcutaneous. There was no obvious significance between the test group and control group at different periods (P>0.05). Pathological sections showed that the peripheral packed tissue of materials and inflammation changer accorded with the general regularity of inflammatory outcome (P<0.05). Part2: The mean microleakage levels, ranked in ascending order are: nano-CPC(4.23±0.768mm), Cortisomol(4.27±0.548mm), and ZoE(5.37±0.822mm). The microleakage levels for all the materials were significantly different (P<0.05), except that similarity existed between nano-CPC and Cortisomol (P>0.05). Part3: The study showed that nano-CPC was able to effectively treatment of periapical periodontitis. In both groups of acute periapical periodontitis and chronic periapical periodontitis, nano-CPC had significantly better results (P<0.05) than zoE at 4 weeks, 8 weeks of acute periapical periodontitis and chronic periapical periodontitis. There was no significant difference between nano-CPC and Cortisomol at different periods (P>0.05).Conclusion: Nano-CPC showed a good biocompatibility, a certain degree of apical root cananl sealing capability, and was able to treat peripheral periodontitis effectively. Therefore, nano-CPC is a satisfactory material as root canal sealer.