Evaluation of gingival fibroblast response to Radiofrequency Glow Discharge treated (RFGDT) resin composite and PMMA abutment surfaces
Alnoury, Arwa Soliman
MetadataShow full item record
It has been noted that clinical healing of the gingival margins around temporary dental-implant abutments is variable and sometimes associated with concurrent loss of crestal bone height before placement of the permanent structures. This research addressed the question as to whether more aggressive surface cleaning of such temporary abutment materials as resin composite and dental acrylic would modify their contact interactions with gingival fibroblast cells in a manner encouraging improved marginal integrity in the oral cavity. Representative resin composite (Evoflow, IvoclarVivadent) and polymethylmethacrylate (PMMA) test pieces were prepared in accord with the current clinical standards for application of these materials as temporary abutments for well-healed dental implants, and cleaned by three techniques of increasing rigor:  ultrasonic treatment in distilled water;  ultrasonic treatment in propanol;  Radiofrequency Glow Discharge Treatment (RFGDT) in residual room air for 3 minutes, following ultrasonic treatment in propanol. The materials' surface properties were characterized at each cleaning step by contact angle measurements to determine Critical Surface Tension (CST) and Surface Energy component values, by Multiple Attenuated Internal Reflection Infrared (MAIR-IR) Spectroscopy for surface layer chemistry, and by both Differential Interference Contrast (DIC) Light and Scanning Electron Microscopy along with Profilometry to distinguish surface textures. Replicate specimens of each type were then incubated with human gingival fibroblast cells to document features of cell attachment, growth and viability by employing the colorimetry-based MTT method related to cellular mitochondrial activity. It was found that cleaning of the specimens in propanol and by RFGDT generally increased their Critical Surface Tensions and calculated polar components of their Composite Surface Free Energies, with no significant modifications of surface texture. Human gingival fibroblast growth was enhanced by the presence of test specimens in all the wells of multi-well tissue-culture polystyrene (TCPS) plates, but the cell growth on individual specimen surfaces was not significantly different among the different cleaning preparations except for simply water-cleaned PMMA which had the least cellular growth and attachment, consistent with its lowest CST value among all specimen types. In contrast, the higher CST RFGDT-cleaned PMMA induced superior growth and metabolic activity in the TCPS test wells surrounding these specimens, which also retained the most attached cells during chemical fixation and handling preparations for DIC Microscopy, leading to the speculation that this increased RFGDT-induced attachment strength is somehow related to induction of a mitogenic response in the neighboring milieu. Moreover, regarding the cell spread areas, overall the cells significantly spread more widely on the dental composite specimens than on the PMMA ones. It is clear from the sum of these findings that application of the additional cleaning step of RFGDT to resin composite and acrylic temporary abutments can be beneficial to the growth and attachment of contacting human gingival fibroblasts.