Histocompatibility And Apical Sealing Ability Of Nanomaterial

Aim: To observe histocompatibility and apical sealing ability of two kinds of nanomaterial. Method: Histocompatibility: Methyl-silicone rubber tubes filled with experimental materials of four groups and empty methyl-silicone rubber tubes were implanted into hypodermic tissues of the 10 SD rats of 4 tubes filled with different experimental materials and 1 empty one each. Group 1: filled with zinc oxide-eugenol sealer (ZOE) (the control group); group 2: filled with nano-zinc-oxide sealer(N-ZO); group 3: filled with hydroxyapatite sealer (HA); group 4: filled with nanohydroxyapatite sealer (NHA). Empty tubes which did not filled any material as empty controls were used to assess the grade of inflammation.After 2 weeks and 12 weeks of implantation, the histological reactions were examined under microscope. The histocompatibility of the four kinds of materials is assessed according to the grades of inflammation. Apical sealing ability: 40 roots of single-rooted teeth were prepared using step-back technique and randomly assigned to one of four groups of ten roots each. The root canals were obturated with gutta-percha and one of the sealers by the lateral condensation technique. Group 1: filled with zinc oxide-eugenol sealer and gutta-percha (ZOE) (the control group); group 2: filled with nano-zinc-oxide sealer and gutta-percha (N-ZO); group 3: filled with hydroxyapatite sealer and gutta-percha (HA); group 4: filled with nanohydroxyapatite sealer and gutta-percha (NHA). In addition there were 4 roots which did not filled as negative and positive controls. The access opening was filled with zinc phosphate cement. The sealer was allowed to set in 100% humidity and at 37℃for 48 hours. The roots, except for the apical 2mm, were coated with sticky wax. The roots were stained with ink, decalcified,dehydrated, and then placed in methysalicylate to make them transparent. The linear dye penetration was assessed using a stereomicroscope ×16 magnification. The apical sealing ability of the materials were assessed according to the length of dye penetration. Results : At 2 weeks, there were statistical difference among the grades of inflammation of four kinds of materials (P<0.01), the grades of inflammation of HA were more milder than that of ZOE (the control group) (P<0.01); at 12 weeks, there were statistical difference among the grades of inflammation of four kinds of materials (P<0.01), the grades of inflammation of N-ZO,HA and NHA were more milder than that of ZOE (the control group) (P<0.01). The measured results for the distance of dye penetration showed among four groups differed significantly(P<0.01), the distance of dye penetration of N-ZO,HA and NHA were less than that of ZOE(the control group) (P<0.01); the distance of dye penetration of N-ZO was less than that of NHA(P<0.05).Conclusion: Nano-zinc-oxide,hydroxyapatite and nanohydroxyapatite have favorable histocompatibility and excellent apical sealing ability, so they are suitable for root filling as root canal sealers.