Bacterial Detection, Deformation, and Torque Loss on Dental Implants with Different Tapered Connections Compared with External Hexagon Connection after Thermomechanical Cycling.

The relationship between bacterial infiltration and internal conical Implant-Abutment Interfaces (IAIs) with different conicities still requires investigations that can offer valuable information in the clinical understanding of peri-implant health. The present study aimed to verify the bacterial infiltration of two internal conical connections with an angulation of 11.5° and 16° with the external hexagonal connection as a comparative after thermomechanical cycling using saliva as a contaminant. Test (n = 10) and control (n = 3) groups were set up. Evaluations were made on torque loss, Scanning Electron Microscopy (SEM), and Micro Computerized Tomography (MicroCT) after performing 2 × 106 mechanical cycles (120 N) and 600 thermal cycles (5°-55° C) with 2 mm lateral displacement. The contents of the IAI were collected for microbiological analysis. There was a difference (p < 0.05) in torque loss of the groups tested; groups from the 16° IAI obtained a lower percentage of torque loss. All groups presented contamination and the analysis of the results shows that the microbiological profile of the IAI differs qualitatively from the profile found in the saliva used for contamination. The mechanical loading affects the microbiological profile found in the IAIs (p < 0.05). In conclusion, the IAI environment may favor a microbiological profile different from that of saliva and the thermocycling condition may alter the microbial profile found in the IAI.

Non-surgical periodontal debridement affects subgingival bacterial diversity in patients with HIV-1 and periodontitis.

BACKGROUND: Following human immunodeficiency virus-1 (HIV-1) infection and antiretroviral therapy, the development of periodontal disease was shown to be favored. However, the influence of HIV-1 infection on the periodontal microbiota after non-surgical periodontal debridement (NSPD) needs a broad comprehension. This work aimed to compare the subgingival microbiological content of patients infected with HIV-1 and controls (non-infected) with periodontitis undergoing NSPD. METHODS: The bacterial profile of subgingival biofilm samples of patients with HIV-1 (n = 18) and controls (n = 14) with periodontitis was assessed using 16S rRNA gene sequencing. The samples were collected at baseline, 30, and 90 days after NSPD. The taxonomic analysis of gingival microbiota was performed using a ribosomal RNA database. The microbiota content was evaluated in the light of CD4 cell count and viral load. RESULTS: Both HIV and control groups showed similar stages and grades of periodontitis. At baseline, the HIV group showed higher alpha diversity for both healthy and periodontal sites. Streptococcus, Fusobacterium, Veillonella and Prevotella were the predominant bacterial genera. A low abundance of periodontopathogenic bacteria was observed, and the NSPD induced shifts in the subgingival biofilm of patients with HIV-1, leading to a microbiota similar to that of controls. CONCLUSIONS: Different subgingival microbiota profiles were identified-a less diverse microbiota was found in patients infected with HIV-1, in contrast to a more diverse microbiota in controls. NSPD caused changes in the microbiota of both groups, with a greater impact on the HIV group, leading to a decrease in alpha diversity, and produced a positive impact on the serological immune markers in patients infected with HIV-1. Control of periodontitis should be included as part of an oral primary care, providing the oral health benefits and better control of HIV-1 infection.

Microbiome of titanium and zirconia dental implants abutments.

OBJECTIVES: This study employed culture-independent molecular techniques to extend the characterization of the microbial diversity of biofilm associated with either titanium or zirconia implant-abutments, including not-yet-cultivated bacteria species, and to identify and quantify species recovered from peri-implantar/periodontal sulci, supragingival biofilm and the internal parts of implants. Probing depth, clinical attachment level, bleeding on probing, and marginal bone level were also evaluated over time and correlated with biofilm formation. METHODS: Twenty healthy participants were analyzed. DNA-Checkerboard and 16S-rDNA-Pyrosequencing were used to quantify and determine species identity. RESULTS: 161 bacterial taxa representing 12 different phylotypes were found, of which 25% were non-cultivable. Species common to all sites belonged to genera Fusobacterium, Prevotella, Actinomyces, Porphyromonas, Veillonella and Streptococcus. While some species were subject-specific and detected in most sites, other species were site-specific. Moderate to higher levels of unclassified species were found colonizing titanium-related sites. Pathogenic and non-pathogenic species were detected colonizing oral sites in both materials. Titanium-related sites presented the highest total microbial count and higher counts of pathogenic species. CONCLUSIONS: Our results revealed differences regarding microbial diversity and microorganisms counts in oral biofilm associated with titanium or zirconia. The obtained data suggests a possible relation between microbiological findings and clinical outcomes. SIGNIFICANCE: Next-generation methods of detection have provided new insights on complex microbiota colonizing different sites of oral cavity. The present study demonstrates relevant differences in the communities and microbial counts colonizing different tested substrates with consequent significant differences in the clinical-outcomes, suggesting a probably different mechanism for specific bacterial adhesion.