Graphene-Catechol Dental Sealant: Antibacterial and Mechanical Evaluation

This study evaluates the antibacterial activity, bond strength, fracture pattern, nanohardness, indentation modulus, indentation creep, and elastic part of indentation work of three experimental dental sealants: Control; G (Control with 0.25% graphene); and Gd (Control with 0.25% graphene modified by 3,4-dihydroxyphenyl-L-alanine). For antibacterial activity, samples (n = 10) are incubated with Streptococcus mutans (S. mutans) or Lactobacillus casei (L. casei). S. mutans colony-forming units (CFUs) growth is statistically analyzed; L. casei CFUs growth is analyzed descriptively. Bond strength is tested by shear of sealant pillars on enamel (n = 8). Mechanical tests are performed using a Vickers indenter initially (T0) and after water storage (T1) (n = 8). Control shows the highest S. mutans CFUs (100%). G and Gd show 57.2% and 67.0% reductions, respectively, with no statistical difference. L. casei growth decreases as follows: Control > G > Gd. Bond strength is similar across groups (≈16.6 MPa), with predominantly adhesive failures. In general, at both time points, Gd shows the highest nanohardness and indentation modulus (e.g., 15.05 HV and 0.62 MPa higher than Control and G, respectively, at T1). Control has the highest creep; G and Gd shows the highest elastic part of indentation work. Only Control's nanohardness declines from T0 to T1. Overall, Gd demonstrates promising antibacterial and mechanical performance.