Abstract: PURPOSE: To investigate the impact and underlying mechanisms of digital cobalt-chromium alloy porcelain crowns and zirconia all-ceramic crowns restoration on periodontal health in patients with tooth defects. METHODS: A total of 26 patients with tooth defects who were treated in the Second People's Hospital of Kashi Region from March to June 2024 were selected and randomly divided into cobalt-chromium alloy ceramic crown group (n=13) and zirconia all-ceramic crown group (n=13). After 6 months of restoration, the periodontal health status of the two groups was evaluated, including gingival index, gingival bleeding index, plaque index, caries loss index and loss of clinical attachment. In addition, clinical plaque samples from patients were collected for 16S rRNA sequencing and data analysis to compare the characteristics of different flora in the two groups of samples. The samples of gingival crevicular fluid were collected and proteomic analysis was used to screen the differentially expressed proteins, and the biological process and functional pathway of their enrichment were discussed. RESULTS: After 6 months of restoration, the gingival index, plaque index, and caries loss and repair index in the zirconia all-ceramic crown group were significantly lower than those in the cobalt-chromium porcelain crown group (P<0.05). Although there was no significant difference in the α-diversity indexes of the plaque samples between the two groups, significant differences were observed in the microbial composition: Scardovia, Granulicatella, and Eikenella were significantly enriched in the zirconia all-ceramic crown group, while Peptococcus and Treponema were enriched in the cobalt-chromium porcelain crown group. In addition, a total of 105 differentially expressed proteins were identified by proteomic analysis, and these differentially expressed proteins were significantly enriched in metabolic related biological processes and functional pathways such as fatty acid metabolism and amino acid metabolism. CONCLUSIONS: Zirconia all-ceramic crowns are superior to cobalt-chromium alloy porcelain crowns in terms of periodontal health for patients with dental defects, with less detrimental impact on oral microbiome, suggesting that zirconia crowns have a high clinical application value. The discovery of differential bacteria and differential expressed proteins provides potential biomarkers for early prediction of periodontal diseases and the development of personalized treatment plans.

Key words: Tooth defect, Cobalt-chromium porcelain crown, Zirconia all-ceramic crown, 16S rRNA sequencing analysis, Proteomic analysis