Konstantin Johannes Scholz

Soon after the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, preprocedural mouthwashes were recommended for temporarily reducing intraoral viral load and infectivity of individuals potentially infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in order to protect medical personnel. Particularly, the antiseptic cetylpyridinium chloride (CPC) has shown virucidal effects against SARS-CoV-2 in vitro. Therefore, the aim of this randomized controlled clinical trial was to investigate the efficacy of a commercially available mouthwash containing CPC and chlorhexidine digluconate (CHX) at 0.05% each in SARS-CoV-2–positive patients as compared to a placebo mouthwash. Sixty-one patients who tested positive for SARS-CoV-2 with onset of symptoms within the last 72 h were included in this study. Oropharyngeal specimens were taken at baseline, whereupon patients had to gargle mouth and throat with 20 mL test or placebo (0.9% NaCl) mouthwash for 60 s. After 30 min, further oropharyngeal specimens were collected. Viral load was analyzed by quantitative reverse transcriptase polymerase chain reaction, and infectivity of oropharyngeal specimens was analyzed by virus rescue in cell culture and quantified via determination of tissue culture infectious doses 50% (TCID 50 ). Data were analyzed nonparametrically (α = 0.05). Viral load slightly but significantly decreased upon gargling in the test group ( P = 0.0435) but not in the placebo group. Viral infectivity as measured by TCID 50 also significantly decreased in the test group ( P = 0.0313), whereas there was no significant effect but a trend in the placebo group. Furthermore, it was found that the specimens from patients with a vaccine booster exhibited significantly lower infectivity at baseline as compared to those without vaccine booster ( P = 0.0231). This study indicates that a preprocedural mouthwash containing CPC and CHX could slightly but significantly reduce the viral load and infectivity in SARS-CoV-2–positive patients. Further studies are needed to corroborate these results and investigate whether the observed reductions in viral load and infectivity could translate into clinically useful effects in reducing COVID-19 transmission (German Clinical Trials Register DRKS00027812).

Teeth with different chemical compositions can show vastly different physical properties, so knowledge of elemental composition is required to use animal teeth as substitutes for human teeth in research. In vitro, energy dispersive X-ray spectroscopy (EDX), improved by calibration standards and Si3N4-window material, enables determining local elemental compositions of inorganic and organic compounds without sample destruction. Six human molars, bovine incisors, murine incisors, and murine molars were analyzed. EDX-field scans and line scans were analyzed for elements Ca, P, O, C, N, F, Na, Mg, Fe, Cl, and S. Furthermore, Ca/P- and Ca/N-Ratios were calculated. The presence of iron in murine incisor enamel was investigated using additional wavelength dispersive X-ray spectroscopy measurements (WDX) near the enamel surface. Bovine and human enamel and dentin revealed close similarities regarding elemental composition. The median (25–75% percentiles) of At%Ca was 21.1 (20.8–21.3) in human enamel, 21.0 (20.7–21.2) in bovine enamel, and in murine enamel, 18.3 (17.85–18.88) for molars and 18.35 (18.00–18.75) for incisors. In dentin, murine teeth revealed a higher At%Ca compared to human and bovine teeth. Significant differences between human and bovine teeth were found for nitrogen in dentin, with a median of 4.5 (3.3–5) At%N for human dentin and 2.7 (2.3–3.2) At%N for bovine dentin. The Ca/P-Ratio was the highest in human and bovine enamel, which did not differ significantly. Enamel from murine molars had a higher Ca/P-Ratio than murine incisors and the highest Ca/P-Ratio in dentin was observed for human teeth and murine molars (1.49). WDX revealed iron in the outer 10 µm of pre- and post-eruptive enamel of murine incisors. Pre- and post-eruptive enamel on murine incisors only differed significantly in At%Ca (p = 0.041) and At%P (p = 0.026) with both At% higher in the pre-eruptive enamel. Murine teeth differ significantly from human and bovine teeth in terms of the elemental composition of enamel and dentin.

Aim The aim of the study was to investigate the influence of cavity cleaning and conditioning on marginal integrity of directly placed post‐endodontic composite class‐I‐restorations in vitro . Methodology A total of 168 fully intact teeth without caries or fillings received pre‐endodontic composite restorations (class‐II) after their extraction. Occlusal endodontic access‐cavities were prepared, and root canals were instrumented and filled with gutta‐percha and an epoxy resin‐based sealer. Prior to post‐endodontic class‐I‐restoration, access cavities were completely contaminated with sealer, cleaned with alcohol and pre‐treated as follows: cleaner only (alcohol), glycine‐polishing, Al 2 O 3 sandblasting, carbide bur (immediate as well as delayed restoration). A positive control (not contaminated with sealer and adhesive used) and negative control (cleaner used but no adhesive) were established. Half of the teeth from each group were subjected to thermocycling and mechanical loading (TCML). Marginal integrity of post‐endodontic restoration was evaluated in oro‐vestibular or mesio‐distal sections after AgNO 3 dye penetration (DP) by standardized photomacroscopic imaging and expressed in per cent of margin length along all segments and separately for enamel, dentine and composite, respectively. Results were analysed non‐parametrically ( α = .05). Results No restorations or teeth fractured or debonded completely. Without TCML, the median DP of all segments was significantly higher for the negative control compared with all other groups in oro‐vestibular cutting direction (53%; p = .002) and in mesio‐distal cutting direction (51%; p ≤ .041). The other groups without TCML revealed 16%–24% DP (oro‐vestibular) and 12%–24% DP (mesio‐distal). With TCML, the median DP in oro‐vestibular cutting direction for all segments ranged between 48% and 62% for all groups, a significant difference was only observed between glycine‐polishing and carbide bur ( p = .041). In mesio‐distal cutting direction, the median DP in negative control was 69% with TCML and significantly higher compared with all other groups ( p = .002). For all other groups, the median DP of all segments ranged between 28% and 40% with TCML without significant differences. Error rates method (k = 7) revealed a significant influence of TCML in general on penetration of all segments in both oro‐vestibular and mesio‐distal cutting directions. Conclusion Additional access cavity pre‐treatment after alcohol cleaning did not improve the marginal integrity of post‐endodontic composite restorations. Thorough cleaning of the access cavity with alcohol seems to assure an acceptable marginal integrity to the tooth and restorative composite.