The aim of this study was to evaluate the intraosseous biocompatibility of silver nanoparticles implanted in mandibular bone of guinea pigs.

Two teflon carriers loaded with 0.02% silver nanoparticle gel and calcium hydroxide paste were respectively implanted into either side of the mandibles of 20 guinea-pigs. After 4 and 12 weeks, guinea-pigs were killed, and the specimens were prepared for routine histological examination. Inflammation responses were evaluated by light microscope. The results were analyzed by Kruskal-Wallis nonparametric test.

After 4 weeks, the inflammation scores of 3 samples were 0, and the other 7 samples were 1 in 0.02% silver nanoparticle gel group. Chronic inflammatory cells such as lymphocytes and polykaryocytes were found under light microscopy. The scores of 5 samples in the group of calcium hydroxide were 1, andthe other 5 samples were 2. The root canal paste were partly absorbed, and granulation tissues grew into the carriers. A significantly statistical difference was found between the scores of the two groups(Z=2.805, P=0.005). After 12 weeks, the scores of 8 samples in silver nanopartical group were 0, and the other 2 samples were 1. In calcium hydroxide group, 6 samples were scored 0, and the other 4 samples were scored 1. Both was no significant difference(Z=0.951, P= 0.342).

Silver nanoparticle shows good biocompatibility in bone tissue and should be further evaluated as an intra-canal medicament during root canal therapy.