To evaluate the radiological bone loss and survival outcomes of teeth adjacent to dental implants (TAIs) in comparison to non-adjacent teeth (TNIs) of similar type and baseline condition, using a matched retrospective cohort design. This retrospective study included 233 patients treated with 348 implants between 2013 and 2020 at the University of Freiburg. A total of 480 TAIs and 348 matched TNIs were observed over a mean follow-up of 54 months. Radiographic bone levels, survival rates, and restorative interventions were compared. Control teeth (TNIs) were matched by tooth type and jaw location. Statistical analyses included t-tests, Chi-squared tests, Kaplan-Meier survival analysis, and multivariate Cox-regression. TAIs demonstrated significantly greater bone loss than TNIs (mean: 4.3 % (SD 6.8 %, median: 1.6 %, IQR: 0 - 6.1 %) vs. mean 3.1 % (SD 5.23 %, median: 0.9 %, IQR: 0 - 4.4 %), p = 0.005). New crown restorations were significantly more frequent in TAIs (14.4 %) than TNIs (7.3 %, p = 0.04), though differences in root canal therapy rates were not significant. Survival analysis showed higher 5-year survival rates for TNIs compared with TAIs (93.6 % vs. 88.6 %, p = 0.015). After adjustment for relevant covariates, implant adjacency showed only a limited association with tooth survival, and a stronger association with restorative factors. The most common causes of TAI loss were root fracture and caries. Teeth adjacent to dental implants showed higher rates of bone loss and restorative interventions compared with TNI. This is the first investigation on TAI-survival with respect to preexisting restorative and site-specific conditions of both the TAI and the control teeth, indicating that restorative and endodontic conditions play a greater role than implant adjacency itself. The findings indicate that implant adjacency has a limited effect on the survival of neighboring teeth when tooth-related factors are adequately controlled. Pre-existing restorative conditions, particularly crown restorations and root canal treatment, seem to play a more important role and should be considered in treatment planning and long-term follow-up.

Aim: The oral cavity represents a reservoir for antimicrobial resistance, and supragingival biofilms contribute to reduced antibiotic susceptibility. This study aimed to compare the antimicrobial susceptibility and biofilm-forming capacity of bacterial isolates obtained from dentally healthy individuals and participants with active carious lesions. Methods: A total of 319 bacterial isolates from 40 participants were tested for susceptibility to clinically relevant antibiotics using disk diffusion and Etest methods, supplemented by β -lactamase testing. Biofilm formation was quantified by crystal violet staining and categorized into three levels based on optical density. Statistical analyses accounted for clustering of isolates within individuals. Results: Resistant isolates were detected across all examined taxa. Significant group differences were observed for Veillonella parvula and Lachnoanaerobaculum saburreum . V. parvula isolates from caries participants showed higher proportions of intermediate or resistant classifications to ampicillin and a different distribution of biofilm categories compared to isolates from healthy individuals. For L. saburreum , resistant isolates from the healthy group were more frequently associated with stronger biofilm formation. Across species, stronger biofilm formation was generally associated with higher resistance among obligate anaerobes. Conclusion: Specific bacterial taxa showed distinct differences in antibiotic susceptibility and biofilm-forming capacity between caries and healthy participants. The findings indicate that supragingival biofilms from caries-active individuals may harbour altered resistance patterns, particularly among obligate anaerobic species. These isolate-level observations underscore the need to further investigate how caries-associated ecological shift in oral biofilms relate to antimicrobial resistance.

Objective: This study investigated the impact of the Sudanese smokeless tobacco Toombak on cultivable oral bacteria, its potential antibacterial properties, and its own microbial composition. Materials and methods: Oral swabs from 20 adult male participants, including ten long-term Toombak users and ten non-users, were analyzed through microbial inoculation and identification techniques. In addition, Toombak samples were examined for viable microorganisms, tested for antibacterial activity against selected reference strains, and the results were statistically analyzed using the Wilcoxon rank-sum test (α = 0.05). Results: The overall bacterial counts, diversity, and species distribution showed no statistically significant differences between users and non-users, with the exception of Schaalia odontolytica ( p = 0.0306) and the proportion of Gram-positive rods ( p = 0.0137) expressed as percentages, which were more frequent in the control group. Toombak itself harbored mainly Bacillus spp., and no inhibitory activity against the tested bacteria was observed. While a non-significant trend toward lower bacterial counts was observed in Toombak users (1.83 × 10⁸ vs. 3.31 × 10⁸ CFU/ml), this finding should be interpreted cautiously given the exploratory design and substantial interindividual variability. Conclusion: Further studies using larger cohorts and culture-independent methods are warranted to better clarify its microbial impact.

Repeated exposure to subinhibitory concentrations of antiseptics may lead to reduced susceptibility or resistance and potentially promote cross-resistance to antibiotics. However, the underlying molecular mechanisms remain incompletely understood. This study investigated whether antiseptic-adapted Escherichia coli strains exhibit altered protein expression profiles compared with wild-type (WT) E. coli. Protein expression was analysed in E. coli strains previously adapted over ten passages to subinhibitory concentrations of chlorhexidine (CHX), cetylpyridinium chloride (CPC), and benzalkonium chloride (BAC). WT bacteria were exposed to sub-minimum inhibitory concentrations (sub-MICs) of antiseptics for 3 h to induce stress. Untreated WT and heat-shocked WT E. coli (42 °C, 2 h) served as controls. Protein expression profiles were assessed using SDS-PAGE and Western blotting targeting stress-associated proteins. SDS-PAGE demonstrated altered protein expression patterns in antiseptic-adapted strains, including differences in band intensities and additional protein bands. Western blot analysis showed increased DnaK and GroEL expression with reduced LexA levels in heat-shocked WT bacteria, whereas RecA remained largely unchanged. Antiseptic-adapted strains exhibited increased DnaK, GroEL, and OmpF expression together with reduced LexA and RecA expression. These findings indicate that adaptation to antiseptics involves complex mechanisms among multiple proteins rather than a single adaptive mechanism.