Phenotypic Adaptation to Antiseptics and Effects on Biofilm Formation Capacity and Antibiotic Resistance in Clinical Isolates of Early Colonizers in Dental Plaque.

Despite the wide-spread use of antiseptics in dental practice and oral care products, there is little public awareness of potential risks associated with antiseptic resistance and potentially concomitant cross-resistance. Therefore, the aim of this study was to investigate potential phenotypic adaptation in 177 clinical isolates of early colonizers of dental plaque (Streptococcus, Actinomyces, Rothia and Veillonella spp.) upon repeated exposure to subinhibitory concentrations of chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC) over 10 passages using a modified microdilution method. Stability of phenotypic adaptation was re-evaluated after culture in antiseptic-free nutrient broth for 24 or 72 h. Strains showing 8-fold minimal inhibitory concentration (MIC)-increase were further examined regarding their biofilm formation capacity, phenotypic antibiotic resistance and presence of antibiotic resistance genes (ARGs). Eight-fold MIC-increases to CHX were detected in four Streptococcus isolates. These strains mostly exhibited significantly increased biofilm formation capacity compared to their respective wild-type strains. Phenotypic antibiotic resistance was detected to tetracycline and erythromycin, consistent with the detected ARGs. In conclusion, this study shows that clinical isolates of early colonizers of dental plaque can phenotypically adapt toward antiseptics such as CHX upon repeated exposure. The underlying mechanisms at genomic and transcriptomic levels need to be investigated in future studies.

Influence of COVID-19 Restrictions on Patients' Self-reported Oral Health Care Needs.

PURPOSE: To assess how current COVID-19 restrictions regarding elective dental procedures influence patients' self-reported oral health care needs at a University Hospital in Germany. MATERIALS AND METHODS: Patients with COVID-19 induced cancellation of elective treatment appointments previously scheduled for the period March 16th to April 30th 2020 were contacted by telephone and questioned about the occurrence of oral health problems, pain, self-reported treatment needs, and the use of emergency dental services. Data were analysed retrospectively. RESULTS: Information on 370 patients aged between 1 and 91 years was included. 16.2% (n = 60) of patients reported having experienced an oral health problem for which they requested timely dental treatment. Within this group, the most frequent complaints were pain or tooth hypersensitivity (42.4%, n = 26), insufficient restorations (28.8%, n = 17) and gingival or periodontal problems (23.7%, n = 14). Associations between the type of treatment pending and the report of an oral health problem were considerable for patients awaiting treatment under full anesthesia, surgical procedures and endodontic treatment (p = 0.001; 0.003 and 0.048, respectively). Problems were reported most frequently in these treatment groups, ranging from 27.7% to 100%, compared to 12.6% among patients scheduled for routine check-ups. Overall, 8.6% (n = 32) were experiencing pain, of whom 5 patients experienced constant pain. However, only 1.9% (n = 7) of patients made use of emergency dental services. CONCLUSIONS: The results suggest that while the postponement of routine check-ups is justifiable during emergency situations, the long-term cancellation of surgical and endodontic therapies must be viewed critically.