Biofilm and Cell Adhesion Strength on Dental Implant Surfaces via the Laser Spallation Technique

ObjectivesThe aim of this study is to quantify the adhesion strength differential between an oral bacterial biofilm and an osteoblast-like cell monolayer to a dental implant-simulant surface and develop a metric that quantifies the biocompatible efficacy of implant surfaces. MethodsHigh-amplitude short-duration stress waves generated by laser pulse absorption are used to spall bacteria and cells from titanium substrates. By carefully controlling laser fluence and calibration of laser fluence with applied stress, the adhesion difference between dental carry Streptococcus mutans biofilms and MG 63 osteoblast-like cell monolayers on smooth and rough titanium substrates is obtained. The Adhesion Index consists of a ratio of cell adhesion strength to biofilm adhesion strength obtaining a nondimensionalized parameter for biocompatibility assessments. ResultsAdhesion strength of 145{+/-}42 MPa is measured for MG 63 on smooth titanium, which increases to 288{+/-}24 MPa on roughened titanium. Adhesion strength for S. mutans on smooth titanium is 315{+/-}9 MPa and remained relatively constant at 332{+/-}9 MPa on roughened titanium. The Adhesion Index for smooth titanium is 0.46{+/-}0.12 which increased to 0.87{+/-}0.05 on roughened titanium. SignificanceThe laser spallation technique provides a platform to examine the tradeoffs of adhesion modulators on both biofilm and cell adhesion. This tradeoff is characterized by the Adhesion Index, which is proposed to aid biocompatibility screening and could result in improved implantation outcomes. The Adhesion Index is implemented to determine surface factors that promote favorable adhesion of cells greater than biofilms. Here, an Adhesion Index >> 1 suggests favorable biocompatibility. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/873240v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@c661ecorg.highwire.dtl.DTLVardef@46f768org.highwire.dtl.DTLVardef@11cfd33org.highwire.dtl.DTLVardef@3321e4_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIBiofilm and cell monolayer adhesion are measured via the laser spallation technique C_LIO_LISmooth and roughened dental implant-mimicking titanium surfaces are investigated C_LIO_LISurface roughness increases cell adhesion but does not alter the adhesion of biofilms C_LIO_LIAn Adhesion Index is developed to directly quantify the adhesive competition between bacteria and cells on an implant surface C_LI