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Purpose: The COVID-19 pandemic raised the question about the extent of microbial exposure encountered by dentists during dental therapy. The purpose of this study was to quantify microbial counts on surgical masks related to duration and type of dental therapy, as well as patient oral health variables. Materials and Methods: Sterile filter papers were fixed on surgical masks used during routine daily dental therapy. Thereafter, the filter papers were pressed onto blood agar plates for 1 min, before the agar plates were incubated with 10% CO2. After 48 h, the colony forming units (CFU) were counted and microorganisms were identified. The dependence of the CFU counts on treatment and patient-related variables was analysed using linear regression. Results: Filter papers obtained from 322 dental treatments (429 masks) were included in the final analysis. On average, 5.41 ± 9.94 CFUs were counted. While mostly oral bacteria were detected, Staphylococcus aureus was also identified on 16 masks. Linear regression, incorporating patient-related and treatment characteristics through step-wise inclusion, revealed statistical significance (p 0.001) only with the variable “assistance during therapy”. The type of dental treatment exhibited a trend, with fewer CFUs observed in caries treatment compared to periodontal or prosthodontic therapy. Furthermore, after analysing filter papers from masks used by dental assistants in 107 dental treatments, fewer CFUs were found on the masks compared to those used by dentists (p 0.001). Conclusion: The mean number of CFUs observed consistently remained low, highlighting the efficacy of the implemented hygiene measures. Consequently, it is clinically recommended to support dental treatment with precise suction of the generated aerosols. Keywords: aerosols, dental care, dental care team, masks

Purpose: To evaluate the effect of bovine milk and yogurt on selected oral microorganisms and different oral biofilms. Materials and Methods: Milk was prepared from 0.5% fat (low-fat) and 16% fat (high fat) milk powder. For yogurt preparation, the strains Lactobacillus delbrueckii ssp. bulgarcius and Streptococcus thermophilus were added to the milk. Minimal inhibitory concentrations (MIC) and minimal microbiocidal concentrations (MMC) of the test compounds were measured against various microorganisms by the microbroth dilution technique. Cariogenic periodontal biofilms and one containing Candida were created on plastic surfaces coated with test substances. Further, preformed biofilms were exposed to the test substances at a concentration of 100% for 10 min and thereafter 10% for 50 min. Both colony forming units (cfu) and metabolic activity were quantified in the biofilms. Results: Neither high-fat milk, low-fat milk nor casein inhibited the growth of any species. Yogurt and L. delbrueckii ssp. bulgaricus at low MIC and MMC suppressed the growth of Porphyromonas gingivalis and other bacteria associated with periodontal disease. High-fat yogurt decreased cfu in the forming periodontal biofilm by 90%. Both low- and high-fat yogurts reduced metabolic activity in newly forming and preformed periodontal and Candida biofilms, but not in the cariogenic biofilm. Conclusions: Yogurt and L. delbru eckii ssp. bulgaricus, but not milk, were bactericidal against periodontopathogenic bacteria. Yoghurt reduced the metabolic activity of a Candida biofilm and a periodontal biofilm. Yogurt and L. delbrueckii ssp. bulgaricus may have potential in prevention and therapy of periodontal diseases and Candida infections. Keywords: Candida, caries, milk products, oral bacteria, periodontitis

Objective: The aim of the present study was to evaluate the antimicrobial influence of different root canal filling techniques using gutta-percha and an epoxy resin-based sealer in experimentally infected root canals of extracted human teeth. Method and Materials: In total, 96 intact sterilized, permanent human anterior teeth and premolars with single patent root canals were prepared and infected with a clinical isolate of Enterococcus faecalis. After 72 hours, all root canals were sampled using three sterile paper points. The tooth specimens were randomly divided into three groups and a control of 24 specimens each, according to the respective obturation techniques: lateral condensation (LC group), ProTaper Thermafil (PT group), and vertical compaction technique (VC group). AH Plus was used as sealer. The control group was left untreated (without root canal filling). After 7 days root canal fillings were removed and collected. The root canals were sampled using three sterile paper points and dentin chips were obtained from the root canal walls. The samples were cultured on blood agar, and colony forming units were counted. Results: All root canal filling techniques significantly reduced bacterial viability, eliminating more than 99.9% of E faecalis. In the LC group, three (13%) root canals were culture negative. In the PT group, 21 (88%) root canals and in the VC group 15 (54%) were culture negative. Conclusion: All root canal filling techniques significantly reduced E faecalis in root canals. In cases where warm filling techniques can be applied, these should be preferred to cold obturation. Keywords: bacteria, gutta-percha, lateral compaction, sealer, Thermafil, vertical compaction

Die gründliche Desinfektion und eine bakteriendichte Wurzelkanalfüllung bis zur apikalen Konstriktion des Wurzelkanals stellen die essenziellen Bestandteile einer erfolgreichen endodontischen Behandlung dar. Da eine apikale Barriere infolge von Störungen des Wurzelwachstums oder apikalen Resorptionsprozessen fehlen kann, sind in solchen Fällen Techniken anzuwenden, die das Ziel haben, eine apikale Barriere zu schaffen. Die Apexifikation mithilfe von Kalziumhydroxid-Einlagen in das Wurzelkanalsystem stellt eine bewährte Methode dar, die - über einen längeren Zeitraum angewendet - die Bildung einer apikalen Hartgewebsbarriere induzieren kann. Alternativ stehen biokompatible Zemente wie zum Beispiel der modifizierte Portlandzement Mineral Trioxid Aggregat (MTA) zur Verfügung, um diese apikale Versiegelung des Wurzelkanalsystems in einem weitaus kürzeren Zeitraum zu ermöglichen. Hierbei handelt es sich aber um einen apikalen Verschluss, nicht um eine klassische Apexifikation mit körpereigenem Hartgewebe. Im vorliegenden Beitrag wird die endodontische Behandlung eines Frontzahnes einer 15-jährigen Patientin mit offenem Apex nach Trauma und ausbleibendem Abschluss des Wurzelwachstums beschrieben. Keywords: Wurzelkanalbehandlung, Apexifikation, Trauma, Kalziumhydroxid, MTA, Parodontitis apicalis