Enhancement of peripheral seal of medical face masks using a 3-dimensional-printed custom frame.

BACKGROUND: During the COVID-19 pandemic, American Society for Testing and Materials level 3 and level 2 medical face masks (MFMs) have been used for most health care workers and even for the first responders owing to a shortage of N95 respirators. However, the MFMs lack effective peripheral seal, leading to concerns about their adequacy to block aerosol exposure for proper protection. The purpose of this study was to evaluate the peripheral seal of level 3 and level 2 MFMs with a 3-dimensional (3D-) printed custom frame. METHODS: Level 3 and level 2 MFMs were tested on 10 participants with and without a 3D-printed custom frame; the efficiency of mask peripheral seal was determined by means of quantitative fit testing using a PortaCount Fit Tester based on ambient aerosol condensation nuclei counter protocol. RESULTS: The 3D-printed custom frame significantly improved the peripheral seal of both level 3 and level 2 MFMs compared with the masks alone (P < .001). In addition, both level 3 and level 2 MFMs with the 3D-printed custom frame met the quantitative fit testing standard specified for N95 respirators. PRACTICAL IMPLICATIONS: The 3D-printed custom frame over level 3 and level 2 MFMs can offer enhanced peripheral reduction of aerosols when using collapsible masks. With the shortage of N95 respirators, using the 3D-printed custom frame over a level 3 or level 2 MFM is considered a practical alternative to dental professionals.

Changes of Surface Properties of Composite Preveneered Stainless Steel Crowns After Prophy Polishing to Remove Stains.

PURPOSE: The purpose of this study was to assess the effect of fine-, medium-, and coarse-grit prophy paste used to polish grape juice-stained preveneered stainless steel crowns (PvSSCs). METHODS: Forty-five maxillary central incisor PvSSCs were immersed in grape juice for 30 days and randomly assigned to three groups (n equals 15) using fine-, medium-, and coarse-grit prophy paste for polishing. Color measurement (L*a*b*), surface roughness (Ra), and scanning electron microscopy imaging were performed at prestain, poststain, and postpolish periods. The significance level was P<.05. RESULTS: From prestain to poststain, the change in color (ΔE) was 5.4; poststain to postpolish it was 4.7. The overall ΔE value from prestain to postpolish was 1.7, meaning that there was no overall perceivable color change. There was no significant color difference among the three grit groups. The Ra value of prestain (0.047 µm) and poststain (0.050 µm) were significantly lower than postpolish (0.209 µm; P<.001). After polishing, the mean Ra value of the fine-grit polish was 0.164 µm; for the medium-grit polish, it was 0.229 µm; and for the coarse-grit polish, it was 0.232 µm. CONCLUSION: The composite facings were susceptible to grape juice stains, and all three grit prophy pastes removed stains equally effectively. A fine-grit prophy paste is preferred over medium- and coarse-grit to minimize the amount of surface roughness change.