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Antimicriobial potential and cytotoxicity of hexamethyldisiloxane film incorporated with chlorhexidine on the titanium surface

Full text
Author(s):
Adaias Oliveira Matos
Total Authors: 1
Document type: Doctoral Thesis
Press: Piracicaba, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
Defense date:
Examining board members:
Valentim Adelino Ricardo Barão; Richard Lee Gregory; Elidiane Cipriano Rangel; Francisco Humberto Nociti Junior; Cinthia Pereira Machado Tabchoury
Advisor: Valentim Adelino Ricardo Barão
Abstract

A stable connection between the titanium surface and the abutment and peri-implant oral tissues is an important prerequisite for long-term dental implant success. Thus, this surface should minimize the bacterial colonization while allowing a good adhesion of the oral tissues. Therefore, the objective of this study is to synthetize a hexamethyldisiloxane film incorporated with chlorhexidine (CHX) and to investigate its antimicrobial and cytotoxicity potentials on the commercially-pure titanium (cpTi) surface. In the first chapter, three concentrations of CHX (2, 3 and 5 wt%) were used in the experimental groups. Surfaces without CHX and the bulk surface (machined) of cpTi were used as controls. The chemical and physical surface characterizations were performed using different techniques. CHX-release was determined by UV-spectrophotometer. In the microbiological assay, biofilms of Streptococcus sanguinis were grown on discs surfaces for 2, 24, 48, and 72 h, and live/dead cells and the number of viable microorganisms were determined. Fibroblasts cells (F3T3) were used to assess cell viability, morphology and inflammatory response at 1, 2, 3, and 4 days. CHX films uniformly coated the discs. The thin films either with or without CHX increased the wettability and the surface free energy of the bulk cpTi (p<0.05) while maintaining surface roughness compared to the machined controls. CHX-release was obtained over an 11 day period. All concentrations of CHX exhibited biofilm inhibition (from 40 to 80% reduction in biofilm bacterial numbers) during all periods (p<0.05). The greatest biofilm inhibition was noted for 2% CHX in the periods of 48 and 72 h of biofilm formation (p<0.05). Treatments with 2 and 3% CHX did not affect the viability of F3T3 cells (p>0.05). However, 5% CHX concentration reduced the cell density over the course of days. The F3T3 cells exhibited good cell spreading on the 2% CHX treated discs after 4 days of incubation compared to the 3 and 5% CHX. Treatment with 5% CHX induced inflammatory response by upregulating the levels of IL-4, IL-17, and TNF-? at day 3, and IFN-y at days 3 and 4 (p<0.05). The secretion of IL-6 was significantly lower to the treatment with 2% CHX than in the machined control at days 1, 2 and 4. In the second chapter, films without and with CHX (2%) and the machined surface were used in a co-culture with cells of periodontal ligament fibroblasts and S. sanguinis. The co-culture assay were used to assess the immunofluorescence imaging, XTT assay, LDH assay, and WST assay at 1, 2, and 3 days. Treatments with hexamethyldisiloxane films incorporated with CHX did not affect the metabolic activity, cytotoxicity and viability of ligament fibroblasts cells (p>.05). These multifunctional chlorhexidine-doped thin films are able to inhibit the S. sanguinis growth and to destroy the bacterial biofilm without cytotoxic effects on human fibroblasts and allowing an adequate colonization of ligament fibroblasts cells on their surface. Overall, we can conclude that we successfully developed a chlorhexidine-doped thin film onto titanium surface via glow discharge plasma. CHX thin films remained cytocompatible and provided bacteriostatic effects against S. sanguinis at low CHX concentrations. These findings suggest promising applications of these multifunctional chlorhexidine-doped thin films them suitable for future development in dental implant surfaces that inhibit bacterial growth and consequently reduce the cytotoxicity of peri-implant tissues, preventing of periodontal infection. (AU)

FAPESP's process: 16/06117-5 - Development of hexamethyldisiloxane films incorporated with chlorhexidine onto titanium surface: antimicrobial potential and cytotoxicity
Grantee:Adaias Oliveira Matos
Support Opportunities: Scholarships in Brazil - Doctorate