This study aims to determine if the presence of Streptococcus salivarius biofilm changes the tribological response of the tooth/zirconia contact pair. Reciprocating pin-on-plate wear tests were carried out at 37 °C and pH 7, using an appropriate lubricant to simulate an oral environment accounting for the presence of a S. salivarius surface biofilm. Reference wear tests were also carried out in artificial saliva with and without added glucose in aseptic conditions. Tests lasted a total of 21600 cycles under an applied normal load of 1.98 N. Human molar cusps served as pins while medical grade Y-TZP samples were used as sliding plates. Microscopy and profilometry readings were employed for the characterization of pristine and worn surfaces. Enamel/zirconia contact during sliding is notably affected by the presence of a Streptococcus salivarius biofilm. When compared to aseptic reference testing with and without added glucose, the S. salivarius biofilm decreased the dimensional wear factor by 87% and 81% respectively, and decreased the coefficient of friction by 77% and 68% respectively. Results clearly show that a streptococcus biofilm can change the tribological performance of a dental system. This work demonstrates that the presence of biofilm should be appreciated for a dental tribo-sytem, and the authors propose that further works regarding dental wear testing be carried out introducing asepsis level as a fundamental testing parameter.
- Streptococcus salivarius