The influence of the tooth preparation finish line position on the expression of matrix metalloproteinase-9 and the presence of periodontopathogens in the gingival crevicular fluid

OBJECTIVE: The objective of the study was to determine the concentration of matrix metalloproteinase 9 (MMP-9) and changes in the presence of periodontopathogens in the gingival crevicular fluid before and after tooth preparation with the subgingival and equigingival finish line position. PATIENTS AND METHODS: The clinical prospective study included 20 subjects with an indication for upper canine preparation, with the subgingival (group 1) and equigingival finish line (group 2). Samples were taken in four observation intervals: 5 minutes before (control samples), as well as 15 minutes, 24 and 72 hours after tooth preparation (experimental samples). Measurement of MMP-9 was done using Enzyme-linked Immunosorbent Assay (ELISA). The presence of bacteria in the gingival fluid was proven by the Polymerase chain reaction (PCR) analysis. RESULTS: The MMP-9 values did not differ statistically significantly between the groups (p=0.524). The MMP-9 values showed a statistically significant difference in the given observation period (p<0.001) with a significant linear increase in values (p<0.001). A significant quadratic trend recorded a decrease in the MMP-9 values 15 minutes after preparation, and an increase 24 hours after preparation, without a significant difference in the interaction between groups (p=0.392). After preparation, a significant difference in the presence of periodontopathogens was confirmed, i.e., a decrease in the presence of Prevotella intermedia (p=0.025) and Tannerella forsythia (p=0.016) in group 1, and an increase in the presence of Aggregatibacter actinomycetemcomitans in both groups (p=0.029, p=0.026). CONCLUSIONS: The study is a good basis for determining the influence of tooth preparation on gingival inflammation, with therapeutic (choice of preparation technique) and preventive significance regarding the protection of the periodontal tissue from possible iatrogenic damage.