CYTOTOXIC EFFECTS OF DENTAL IMPLANT DEBRIS AFTER DECONTAMINATION TREATMENT USING ER:YAG LASER

Abstract

Introduction: There is a growing body of literature investigating the detrimental effects of titanium and metallic particles in the peri-implant tissues. Metallic particles may be dispersed into the peri-implant tissues during implant placement, micro-mechanical wear, after implant debridement, or through corrosive electrochemical interactions with the adjacent microbiome. Dissolution of these particles into the peri-implant tissue may be an important pathogenic agent in the development of peri-implantitis. Our preliminary study showed that type of implant surface treatment influenced the quantity of particles released after titanium implant decontamination treatment using laser therapy in vitro. To the best of our knowledge, there are no studies evaluating the particle release from ceramic implants after laser irradiation. Purpose: The aim of this study is to investigate the particle release and potential induction of cytotoxicity and inflammatory response after implant decontamination of titanium and ceramic dental implants using laser therapy with an Er:YAG (erbium-doped yttrium aluminum garnet) laser. Materials and Methods: Three yttrium oxide stabilized tetragonal zirconium dioxide dental implants, three Titanium Alloy (Ti-6Al-4V ELI) dental implants with Laser-Lok® and resorbable blast texturing, and three (n = 3) Titanium Alloy (Ti-6Al-4V ELI) non-surface treated dental implants were irradiated using an erbium-doped yttrium aluminum garnet laser (Er:YAG) laser utilizing implant decontamination setting of 100 mJ, 2 W, and 20 Hz. Implants were sonicated in 1 mL of 70% denatured ethyl alcohol for 10 minutes, and 1 mL of supernatant was evaporated for 24 hours to retrieve metallic debris. Wells containing particles were cultured with human adult primary gingival fibroblasts and incubated at 37°C with 5% CO2. Scanning electron microscopy in a high-vacuum acceleration voltage with energy-dispersive X-ray was used to evaluate the morphology and elemental composition of the collected particles and dental implant samples. A firefly luciferase assay was used to determine the cell viability 48 hours, 72 hours, and 96 hours after initial seeding and incubation of the cells. A quantitative sandwich enzyme immunoassay technique was utilized to measure human IL-6 and TNF-α in the cell culture supernatants after 24 hours of incubation. Results: Titanium and zirconia particles were identified in the first two implant groups after laser irradiation. No particles containing elemental titanium were identified in the non-surface treated group. While inflammatory cytokines were detected in sufficient quantities representative of an inflammatory response, no comparison between groups was able to be made due to a lack of statistical power. Positive trends were measured in luminescence and absolute cell count over the four day experimental period in comparison to the medium containing control groups. Conclusions: Within the limitations of this study, ER:YAG laser irradiation generated titanium and zirconia particles from the titanium and zirconia test groups, but due to study design limitations, we are unable to conclude whether the metallic particles induced cytotoxicity or a proinflammatory response of human gingival fibroblast cells.