LK ZAUGG¹, M ASTASOV-FRAUENHOFFER², O OLIVIER BRAISSANT³, I HAUSER-GERSPACH², T WALTIMO², NU ZITZMANN<sup>1

1</sup>Department of Periodontology, Endodontology and Cariology, University Center for Dental Medicine Basel, University of Basel, Hebelstrasse 3, 4056 Basel, ²Clinic for Preventive Dentistry and Oral Microbiology, University Center for Dental Medicine Basel, University of Basel, Hebelstrasse 3, 4056 Basel, ³Center of Biomechanics & Biocalorimetry, c/o Department Biomedical Engineering (DBE), University of Basel, Gewerbestrasse 14, 4123 Allschwil

Peri-implant diseases are primarily related to biofilm formation along the mucosal margin of the peri-implant tissues. Adequate oral hygiene and professional cleaning contribute to the prevention of peri-implantitis. However, thorough biofilm removal is challenging, and the remaining biofilm, particularly in marginal and interproximal regions, enhances the risk of peri-implant disease development.
The present study analysed in vivo biofilm formation and the cleanability on titanium discs with 4 different surfaces (M, machined TiZr alloy; modMA, machined and acid etched TiZr alloy; modSLA, machined, sand blasted and acid etched TiZr alloy; TAV MG, micro-grooved titanium aluminium vanadium alloy) in an experimental model.
Custom-made discs were mounted in individual intraoral splint housings and worn by sixteen volunteers for 24 h. Cleanability of the materials was performed by a standardized cleaning device. Safranin staining assay, isothermal microcalorimetry (IMC) and scanning electron microscopy (SEM) were used for microbiological assessments.
The hydrophilic surfaces modMA and modSLA with greater surface micro-roughness exhibited significantly more biofilm than the hydrophobic surfaces TAV MG and M. The standardized cleaning procedure substantially reduced the biofilm mass on all surfaces. After cleaning, the IMC analyses demonstrated a longer lag time of the growth curve on TAV MG compared to modSLA. Inter- and intraindividual variations in biofilm formation on the titanium discs were evident throughout the study.
The current investigation demonstrated that hydrophilicity and surface roughness drove the initial biofilm adhesion and formation in vivo. Surface topography was the most influential factor for surface cleanability, with the TAV MG surface retaining larger amounts of the initial biofilm hidden within the micro-grooves. The machined surface without grooves was easier to clean, but recolonization indicated by increased metabolic activity (growth rate) in IMC occurred despite mechanical biofilm removal.