Bacterial adhesion on patient-specific implant materials

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Auditorium F101 of the Faculty of Biochemistry and molecular medicine, Aapistie 7

Topic of the dissertation

Bacterial adhesion on patient-specific implant materials

Doctoral candidate

Master of Science Sonia Sarfraz

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Translational Medicine Research Unit

Subject of study



Professor Pekka Vallittu, University of Turku


Docent Justus Reunanen, University of Oulu

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Study of bacterial adhesion on implant materials

Implant-associated infections are a major cause of morbidity and treatment failure after implantation surgery. Initial contamination or later colonization of bacterial pathogens on the biomaterial surface leads to biofilm formation, which is difficult to treat and could result in prolonged antibiotic therapy along with implant removal in some cases. Different surface treatments and the addition of antibacterial coating on these biomaterials are being developed to prevent biofilm production on the implant surface.
This study aimed to assess the bacterial adhesion on patient-specific computer-aided design and computer-aided manufacturing (CAD-CAM) titanium, and polymeric bioresorbable and non-resorbable implant materials. This study investigated the biofilm formation of common pathogens in implant associated infections such as Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Escherichia coli on titanium and its alloys, plastic implant material polyetheretherketone (PEEK), and resorbable polylactic acid (PLA). All material types were tested separately with and without saliva contamination for bacterial adhesion by each bacterial strain.
Results showed no significant difference of tooling and milling techniques on bacterial attachment. Overall, S. aureus was found to be the most adhered strain on most of the materials tested, followed by E. faecalis and E. coli, while the least adhered bacterium was S. mutans. Titanium grade 5 polished and titanium grade 23 showed the maximum level of biofilm formation by most of the pathogens whereas PLA showed less bacterial binding in the majority of the experiments. Salivary pellicle coating significantly increased bacterial biofilm formation by all the strains except for E. coli, which showed no significant difference in saliva and non-saliva-treated materials.
In conclusion, these findings imply that tooling and milling surface treatments had little effect on bacterial attachment, but all materials showed a high degree of bacterial binding. Saliva contamination plays a vital role in favoring pathogens by promoting biofilm formation. Therefore, saliva contamination of implant material should be minimized especially in immunocompromised patients. Remaining trials in this field involve further extensive experimentation in the in vivo models to study the effect of surface treatments on bacterial adhesion and investigate the factors needed to prevent implant associated infections.
Last updated: 4.3.2024