Antibiofilm Activity of LL-37 Peptide and D-Amino Acids Associated with Antibiotics Used in Regenerative Endodontics on an Ex Vivo Multispecies Biofilm Model

The antimicrobial peptide LL-37 and D-amino acids (D-AAs) have been proposed as antibiofilm agents. Therefore, this study aimed to test the antimicrobial effect of antibiofilm agents associated with antibiotics used in regenerative endodontic procedures (the triple antibiotic paste-TAP: ciprofloxacin + metronidazole + minocycline). An endodontic-like biofilm model grown on bovine dentin discs was used in this study. After 21-day growth, the biofilms were treated with 1 mg/mL TAP, 10 μM LL-37, an association of LL-37 + TAP, 40 mM D-AAs solution, an association of D-AAs + TAP, and phosphate-buffered saline (negative control). Colony forming unit (CFU) data were analyzed by two-way ANOVA and Tukey's multiple comparison test (p < 0.05). LL-37 + TAP showed the best antibacterial activity (7-log10 CFU/mL ± 0.5), reaching a 1 log reduction of cells in relation to the negative control (8-log10 CFU/mL ± 0.7) (p < 0.05). In turn, no significant reduction in bacterial cells was observed with TAP, LL-37, D-AAs, and D-AAs + TAP compared to the negative control. In conclusion, the combination of antibiotics and LL-37 peptide showed mild antibacterial activity, while the combination of antibiotics and D-AAs showed no activity against complex biofilms. Keywords: D-amino acids; antibiofilm agents; antimicrobial peptides; oral biofilms; regenerative endodontics; triple antibiotic past

Evaluation of the bioactivity of fluoride-enriched mineral trioxide aggregate on osteoblasts

AIM To investigate whether a combination of mineral trioxide aggregate (MTA) and fluoride compounds affects bone cells. METHODOLOGY Mineral trioxide aggregate (MTA) discs (ProRoot , Dentsply Sirona, Ballaigues, Switzerland) with and without the addition of 0.1%, 0.25% and 0.5% sodium fluoride were characterized for their surface roughness by laser scanning microscopy and for the adhesion of human alveolar osteoblasts by scanning electron microscopy. Using eluates from fluoride-enriched MTA discs, the cell proliferation was measured by monitoring the DNA incorporation of 5-bromo-2'-deoxyuridine. Further, gene expression was evaluated by qPCR arrays, extracellular matrix mineralization was quantified by absorption measurement of Alizarin red stains, and effects were calculated with repeated measures analysis and post hoc P-value adjustment. RESULTS Irrespective of fluoride addition, cell adhesion was similar on MTA discs, of which the surface roughness was comparable. Control osteoblasts had a curvilinear proliferation pattern peaking at d5, which was levelled out by incubation with MTA. The addition of fluoride partly restored the MTA-related reduction in the cellular proliferation rate in a dose-dependent manner. At the mRNA level, both fluoride and MTA modulated a number of genes involved in osteogenesis, bone mineral metabolism and extracellular matrix formation. Although MTA significantly impaired extracellular matrix mineralization, the addition of fluoride supported the formation of mineralized nodules in a dose-dependent manner. CONCLUSION The addition of fluoride modulated the biocompatibility of MTA in terms of supporting bone cell proliferation and hard tissue formation. Hence, fluoride enrichment is a trend-setting advancement for MTA-based endodontic therapies

Robust fuzzy relational clustering of non-linear data

In many practical situations data may be characterized by non-linear structures. Classical (hard or fuzzy) algorithms, usually based on the Euclidean distance, implicitly lead to spherical shape clusters and, therefore, do not identify clusters properly. In this paper we deal with non-linear structures in clustering by means of the geodesic distance, able to capture and preserve the intrinsic geometry of the data. We introduce a new fuzzy relational clustering algorithm based on the geodesic distance. Furthermore, to improve its adequacy, a robust version is proposed in order to take into account the presence of outliers

Microbial adhesion on novel yttria-stabilized tetragonal zirconia (Y-TZP) implant surfaces with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coatings

cited By 2International audienceObjectives: Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation. Materials and methods: The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM). Results: Overall, A and B presented the lowest CFU values for all microorganisms, while C sheltered significantly less E. faecalis, P. aeruginosa, and C. albicans than BES. Compared to the controls, B demonstrated the lowest vitality values for E. coli (54.12 %) and C. albicans (67.99 %). Interestingly, A (29.24 %) exhibited higher eradication rates for S. aureus than B (13.95 %). Conclusions: Within the limitations of this study, a-C:H:N-coated 3Y-TZP surfaces tended to harbor less initially adherent microorganisms and selectively interfered with their vitality. Clinical relevance: This could enable further investigation of the new multi-functional zirconia surfaces to confirm their favorable antimicrobial properties in vivo. © 2015, Springer-Verlag Berlin Heidelberg

Clinical management of fusion in primary mandibular incisors: a systematic literature review

Objective: Dental anomalies occurring in deciduous teeth can affect the eruption of the permanent dentition and the occlusion stability. The occurrence of dental anomalies such as double teeth during the primary dentition in the daily practice might be frequent. The study aimed to qualitatively summarize the therapeutic management of double teeth in primary incisors.Material and Methods: A systematic review regarding the therapy of primary fused incisors in the mandible was performed and the obtained data were assessed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The following electronic databases were screened from 1st January, 1996 until 30th July, 2019: PubMed, Scopus, EBSCO and the archives of paediatric dental journals. The search terms were grouped in anatomic entity: (tooth OR teeth OR incisor), pathological condition: (fused OR fusion OR geminated OR double), intervention: (treatment OR intervention OR therapy OR prevention OR control OR management OR restoration), observed parameters: (primary dentition OR primary tooth OR primary teeth).Results: Ten articles met all inclusion criteria. The data disclosed the occurrence of double teeth in mandibular incisors. The main management of this clinical condition is either preventive or surgical involving the extraction of fused teeth, based on the deciduous nature of the teeth, the degree of caries and malocclusion development risk.Conclusion: An early diagnosis of dental anomalies is fundamental for the application of proper preventive strategies to avoid a potential malocclusion in permanent dentition and to maintain these teeth sound and caries-free until the eruption of the permanent dentition