Biofilm control in printed dentures: Effectiveness of hygiene protocols in base and tooth resins.

Statement Of Problem: Despite the importance of denture hygiene, little is known about how different hygiene protocols perform against multispecies biofilms, including Candida albicans, Staphylococcus aureus, and Streptococcus mutans, on denture surfaces made from conventional versus 3-dimensionally (3D) printed acrylic resins.

Purpose: The purpose of this in vitro study was to evaluate the effect of hygiene protocols on a multispecies biofilm (C albicans, S aureus, and S mutans) formed on resin used for denture bases and teeth.

Material And Methods: Circular specimens (Ø6×2 mm) were made from 3D printed denture resin (n=77) and heat-polymerized resin (n=77). Specimens with multispecies biofilm were randomly assigned to 3 hygiene protocols combining manual brushing with a soft brush and neutral soap (20 seconds per surface) plus immersion in 3 mL distilled water (control, for 20 minutes), Corega Tabs solution (BCt, for 15 minutes), or Nitradine solution (BNt, for 3 minutes). After rinsing in phosphate-buffered saline, the specimens were transferred to Letheen broth, 0.025 mL of the suspension was seeded on selective media, and the plates were incubated for 48 hours at 37 °C. Microbial load was quantified by CFU/mL count, and data were analyzed by the generalized linear model with the Wald test (α=.05). Biofilm viability was assessed by epifluorescence microscopy.

Results: The BNt protocol eliminated S mutans and C albicans (CFU=0). For S aureus, BNt resulted in no detectable growth on either resin (P<.001). BCt reduced microbial load compared with the control for all species (P<.001) but was less effective than BNt. The 3D printed resin showed lower microbial load than the heat-polymerized resin for both base and tooth materials (P<.001). With BCt, the S aureus load was significantly higher on the heat-polymerized resin than on the 3D printed resin (P<.001). Microscopy images confirmed substantial biofilm reductions after both chemical protocols.

Conclusions: Brushing followed by immersion in Nitradine was the most effective hygiene protocol for controlling multispecies biofilm. The 3D printed denture resin demonstrated better resistance to microbial colonization than conventional heat-polymerized resin.