Abstract

Statement of problem: Although feldspathic porcelain is esthetic and biocompatible, it's considered a weak point in zirconia restorations. Researches are necessary to improve its flexural strength without affecting biological properties.
Purpose: to evaluate the possible toxic effects of incorporating ZrO2 Nanoparticles into conventional veneering ceramic system.

Materials & Methods: Four veneering ceramic systems [Ex0, Ex5, Ex10&Ex20] were formulated by incorporating zirconia NPs into feldspathic powder [0%, 5%,10% & 20% wt.] respectively. Twenty dogs were grouped into 4 groups to receive the 4 experimental ceramic systems. The 3rd mandibular premolar for each dog was prepared for zirconia crowns. Impressions were taken for production of zirconia copings, veneered with experimental ceramics & delivered. After 3& 6months gingival specimens were collected& subjected to Real-time PCR test to assess genotoxicity of the 4 experimental veneering ceramics.

Results: No genotoxicity was recorded for all groups in both 3& 6 months. However, appoptic genes recorded in Ex0: 0.64±0.01 &0.65±0.02, Ex5: 0.67±0.02& 0.67±0.01, Ex10:0.72±0.01&0.73±0.02 and in Ex20: 0.88±0.01& 0.89±0.01 compared to control (housekeeping gene) 0.96± 0.01 & 0.99±0.01 for3&6 months respectively. From clinical perspective; No local biological reactions were recorded.

Conclusion: No genotoxic effect was recorded in all groups. whereas, appoptic genes expressed higher level in proportional to NPs ratio. Generally, a satisfactory soft tissue response was observed.