ORAL MICROBIAL DYSBIOSIS INDEX: FROM MICROBIOLOGICAL REPORT TO A SINGLE NUMBER IN PRE-IMPLANT SCREENING

Abstract

Introduction. Microbiological monitoring at the pre-implant stage is gaining increasing clinical importance due to the rising prevalence of antibiotic-resistant strains within the oral microbiota and the established association between the microbiological profile of periodontal pockets and the risk of peri-implant complications. Despite the evident relevance of microbiological screening, routine laboratory reports typically provide only qualitative characterization of the microbiota, lacking a quantitative measure of dysbiotic changes suitable for individual risk stratification and evidence-based clinical decision-making. Aim – to develop and perform a preliminary validation of the Oral Microbial Dysbiosis Index (MDI) – a quantitative parameter for preimplant screening of periodontal pocket microbiota, calculated based on routine bacteriological examination results. Materials and Methods. The study included 59 patients with Stage II-III periodontitis (EFP/AAP, 2017) undergoing pre-implant preparation. Microbiological analysis of periodontal pockets was performed with determination of the antimicrobial resistance (AMR) profile (21 antibiotics). The MDI was calculated as the ratio of non-commensal microorganisms to the total number of identified taxa. The association between MDI and antibiotic resistance levels was assessed using Spearman’s correlation, the Kruskal-Wallis test, and ROC analysis. Results. The mean MDI value was 21,0±19.9% (median 25,0%). Non-commensal microbiota were detected in 55,9% of patients. According to MDI levels, patients were stratified into: low risk (MDI=0%) – 26 (44,1%), moderate risk (MDI>0-33,3%) – 22 (37,3%), and high risk (MDI>33,3%) – 11 (18,6%). A statistically significant correlation was found between MDI and antibiotic resistance level (r = 0,363; p = 0,005). The AMR level in the high-risk group was twice that of the low-risk group (median 2,5 vs 1,0; H = 8,146; p = 0,017). The AUC of MDI for predicting MDR risk was 0,611 (95% CI: 0,463-0,759; threshold 33,3%). Multidrug resistance (MDR) was identified in 23 patients (39,0%); its prevalence increased with rising MDI levels: 30,8% in the low-risk group, 40,9% in the moderate-risk group, and 54,5% in the high-risk group. Conclusions. The MDI is a clinically accessible quantitative parameter that transforms routine microbiological reports into a numerical measure of dysbiotic risk, enabling patient risk stratification at the pre-implant stage. The index demonstrates a statistically significant association with AMR levels (r = 0.363; p = 0.005) and a limited but above-chance discriminatory capacity for MDR (AUC = 0.611; 95% CI: 0,463–0,759). The empirically defined threshold of 33,3% requires confirmation in independent studies.