IADR Abstract Archives
Impact of Oral Bacteria on Enamel Remineralization
Objectives: To investigate the impact of bacteria on enamel crystal growth, a biomimetic mineralization solution, EnamelStrongTM was used to promote the formation of enamel-like hydroxyapatite crystal layers on natural enamel surfaces under neutral pH. The mechanical and chemical properties of the synthesized enamel crystals are assessed in this study.
Methods: Extracted human teeth were sectioned into 0.3mm slices and placed in sealed vials containing bacterial cultures (Streptococcus mutans, Enterococcus faecalis, and Escherichia coli) to grow a dense biofilm. The slices were later immersed in EnamelStrong™ remineralization solution for 48 hours without rinsing and divided into two groups: the experimental group with hexadecyl-pyridium chloride (HDPC) also known as cetyl pyridium chloride (CPC)- a quaternary ammonium antimicrobial compound and the control group without any antimicrobial agents. Two sets of experiments were conducted for each species: one stained with Invitrogen LIVE/DEAD BacLight kits for confocal microscopy (Zeiss LSM 710) to assess bacterial viability and the other set of specimens were fixed by 2.5% glutaraldehyde, serial ethanol dehydrated, and critical point dried (Samdri PVT-3B carbon dioxide critical point drier) then analyzed using Field Emission Scanning Electron Microscopy (FE-SEM, Hitachi SU6600) for microstructure. The hardness and elastic modulus of the crystal layer was measured using nanoindenter (Bruker Hysitron TS 77 Select).
Results: The experiments showed that a hydroxyapatite layer formed on enamel despite the presence of biofilm. The control group showed 2.44 cells/µm2 and 1.3 GPa hardness, while the antibacterial (HDPC) group reported 0.40 cells/µm2 and 3.4 GPa hardness. Confocal analysis confirmed higher bacterial cell death in the experimental group, with more red-stained dead cells.
Conclusions: The use of a calcium and phosphate-based biomimetic mineralization process for enamel rebuilding shows considerable potential. Its ability to promote synthetic enamel with similar mechanical, chemical, and morphological characteristics of natural enamel in the presence of an antimicrobial agent marks a significant advancement in dental remineralization and restoration application.
Methods: Extracted human teeth were sectioned into 0.3mm slices and placed in sealed vials containing bacterial cultures (Streptococcus mutans, Enterococcus faecalis, and Escherichia coli) to grow a dense biofilm. The slices were later immersed in EnamelStrong™ remineralization solution for 48 hours without rinsing and divided into two groups: the experimental group with hexadecyl-pyridium chloride (HDPC) also known as cetyl pyridium chloride (CPC)- a quaternary ammonium antimicrobial compound and the control group without any antimicrobial agents. Two sets of experiments were conducted for each species: one stained with Invitrogen LIVE/DEAD BacLight kits for confocal microscopy (Zeiss LSM 710) to assess bacterial viability and the other set of specimens were fixed by 2.5% glutaraldehyde, serial ethanol dehydrated, and critical point dried (Samdri PVT-3B carbon dioxide critical point drier) then analyzed using Field Emission Scanning Electron Microscopy (FE-SEM, Hitachi SU6600) for microstructure. The hardness and elastic modulus of the crystal layer was measured using nanoindenter (Bruker Hysitron TS 77 Select).
Results: The experiments showed that a hydroxyapatite layer formed on enamel despite the presence of biofilm. The control group showed 2.44 cells/µm2 and 1.3 GPa hardness, while the antibacterial (HDPC) group reported 0.40 cells/µm2 and 3.4 GPa hardness. Confocal analysis confirmed higher bacterial cell death in the experimental group, with more red-stained dead cells.
Conclusions: The use of a calcium and phosphate-based biomimetic mineralization process for enamel rebuilding shows considerable potential. Its ability to promote synthetic enamel with similar mechanical, chemical, and morphological characteristics of natural enamel in the presence of an antimicrobial agent marks a significant advancement in dental remineralization and restoration application.