Development of an antimicrobial, 3D printable denture base material with K18 quaternary ammonium silane-functionalized methyl methacrylate and filler.

STATEMENT OF PROBLEM: Denture base materials are highly susceptible to microbial colonization, which can lead to denture stomatitis. In addition, patients who sleep with their dentures have an increased chance of contracting pneumonia. Commercially available antimicrobial denture base materials to prevent or combat microbial colonization are lacking. PURPOSE: The purpose of this in vitro study was to determine the effects of K18 quaternary ammonium methacryloxy silane-functionalized filler (K18-Filler) and methyl methacrylate (K18-MMA) on the polymerization of 3D printed denture base material and its esthetic, mechanical, and antimicrobial properties. MATERIAL AND METHODS: K18-Filler (0%, 10%, 20% w/w) and K18-MMA (0%, 5%, 12.5% w/w) were added to a 3D printable denture base resin (Denture Base Resin, Original Pink; Formlabs Inc) and 3D printed. Specimens were tested by using the Rockwell15T hardness, near infrared FTIR monomer-to-polymer degree of conversion (DoC), transparency parameter (TP), color shift, and 3-point bend and by counting colony forming units against Streptococcus aureus, Streptococcus sanguinis and Candida albicans tests. Data were analyzed using analysis of variance with the Tukey-Kramer HSD post hoc test. RESULTS: Control resins had significantly higher Rockwell15T hardness than most of the K18 groups (P<.05) but had comparable DoC with all K18 groups except one, showing that all groups were well polymerized. Controls had significantly higher TP than most K18 groups, but most K18 groups had ΔE<3.3, so the color shift was not noticeable. However, the 12.5% K18-MMA with 10% and 20% K18-Filler groups, which were also the groups used to test for antimicrobial activity, had ΔE>8. All K18 groups had comparable or greater moduli than the controls, but the controls had significantly higher ultimate transverse strengths than most K18 groups (P<.05). All 12.5% K18-MMA with K18-Filler groups had significant antimicrobial activity against S. aureus, S. sanguinis, and C. albicans. CONCLUSIONS: 12.5% K18-MMA and K18-Filler produced 3D printable denture materials with comparable polymerization properties and significant antimicrobial properties against S. mutans, S. sanguinis, and C. albicans. High K18-MMA and K18-Filler concentrations caused significant color shifts and reductions in ultimate strengths.

Antimicrobial dental composites with K18-methyl methacrylate and K18-filler.

OBJECTIVE: To determine the effects of using K18-methyl methacrylate (K18-MMA) and K18-Filler on composite cure, esthetic, mechanical, polymerization shrinkage, and antimicrobial properties. METHODS: K18-MMA (0-20% w/w) was used to replace TEGDMA in a 70:30 Bis-GMA:TEGDMA composite filled to 70% w/w with barium glass or K18-Filler. Composite degree of cure (Rockwell15T hardness and near Infrared FTIR), hydrophilicity (contact angle measurements), translucency (transparency parameter measurements, TP), mechanical (3-point bend test), polymerization shrinkage (volumetric shrinkage and shrinkage stress), and antimicrobial properties (colony counting assay) against Streptococcus mutans, Streptococcus sanguinis, and Candida albicans were determined. RESULTS: All experimental groups had comparable degrees of cure (near Infrared FTIR and Rockwell15T Hardness), TP, moduli, polymerization volumetric shrinkages and shrinkage stresses to those of controls (Bonferroni corrected p > 0.0018). Only one group (15% K18-MMA+K18-Filler) had significantly different (lower) contact angles as compared to that of controls (Bonferroni corrected p < 0.0018). Most of the K18-Filler-containing composites had significantly lower ultimate transverse strengths (UTS) than controls (Bonferroni corrected p < 0.0018). Controls had significantly greater S mutans colony counts than 15% and 20% w/w K18-MMA+K18-Filler groups, and greater S sanguinis and C albicans colony counts than K18-containing groups. Of the composites with that provided significant antimicrobial properties against S. mutans, S. sanguinis, and C. albicans, only the 20% K18-MMA+K18-Filler group had significantly lower UTS than controls. SIGNIFICANCE: Composites with K18-MMA and K18-Filler with comparable physical properties to control composites and significant antimicrobial properties have been developed. K18-MMA and K18-Filler seem to be suitable for incorporation into commercial dental resins.

SARS-CoV-2 infection in newborn infants: descriptive epidemiological analysis of cases reported to the Colombian national surveillance system during the first pandemic year, March 2020-February 2021.

OBJECTIVE: To describe the clinical and epidemiological characteristics of newborn infants with SARS-CoV-2 infection notified in the Colombian Public Health Surveillance System. DESIGN: This epidemiological descriptive analysis was conducted using the data of all cases of newborn infants with confirmed SARS-CoV-2 infection notified in the surveillance system. Absolute frequencies and central tendency measures were calculated and a bivariate analysis comparing variables of interest with symptomatic and asymptomatic disease was performed. SETTING: Population-based descriptive analysis. PATIENTS: Laboratory-confirmed COVID-19 cases in newborn infants (aged ≤28 days of life) reported to the surveillance system from 1 March 2020 to 28 February 2021. RESULTS: 879 newborns were identified, corresponding to 0.04% of all reported cases in the country. The mean age at diagnosis was 13 days (range 0-28 days), 55.1% were male and most (57.6%) were classified as symptomatic. Preterm birth and low birth weight were identified in 24.0% and 24.4% of the cases, respectively. Common symptoms were fever (58.3%), cough (48.3%) and respiratory distress (34.9%). A higher prevalence of symptomatic newborns was seen in individuals with low birth weight for gestational age (prevalence ratio (PR): 1.51, 95% CI: 1.44 to 1.59) and newborns with underlying conditions (PR: 1.33, 95% CI: 1.13 to 1.55). CONCLUSIONS: There were a low proportion of confirmed COVID-19 cases in the newborn population. A substantial number of newborns were classified as symptomatic, having low birth weight and being preterm. Clinicians caring for COVID-19-infected newborns should be aware of population characteristics that potentially contribute to disease manifestations and severity.

Outbreak of NDM-1-producing Klebsiella pneumoniae in a neonatal unit in Colombia.

Six multiresistant, NDM-1-producing Klebsiella pneumoniae strains were recovered from an outbreak that affected six neonatal patients in a Colombian hospital. Molecular analysis showed that all of the isolates harbored the blaNDM-1, qnrA, and intI1 genes and were clonally related. Multilocus sequence typing showed that the isolates belonged to a new sequence type (ST1043) that was different from the sequence types that had previously been reported. This is the first report of NDM-1-producing isolates in South America.