Rodrigues, Danieli C.
Permanent URI for this collectionhttps://hdl.handle.net/10735.1/4062
Danieli Rodrigues is an Assistant Professor of Biomedical Engineering. Serving as a Research Engineer within the medical device industry, she developed test methods for performance verification and validation of new designs of hip and knee prostheses and related surgical instrumentation. Her graduate research focused on orthopedic biomaterials, primarily working on the characterization of corrosion and failure mechanisms of hip implants and development of acrylic two-solution bone cements for treatment of spinal compression fractures.
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Browsing Rodrigues, Danieli C. by Subject "Bacteria"
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Item Evaluation of Oral Microbial Corrosion on the Surface Degradation of Dental Implant Materials(Wiley, 2018-08-13) Siddiqui, Danyal A.; Guida, Lidia; Sridhar, Sathyanarayanan; Valderrama, Pilar; Wilson, Thomas G., Jr.; Rodrigues, Danieli C.; 0000-0002-0389-0833 (Rodrigues, DC); Rodrigues, Danieli C.; Siddiqui, Danyal A.; Guida, Lidia; Sridhar, SathyanarayananBackground: Titanium (Ti) dominates as the material of choice for dental implant systems. Recently, titanium-zirconium alloy (TiZr) and zirconia (ZrO₂) have emerged as alternative materials due to higher mechanical strength and lower corrosion susceptibility. Oral pathogenic bacteria can colonize Ti surfaces, leading to surface degradation, which has yet to be investigated on TiZr and ZrO₂. The aim of this study was to compare in vitro oral bacterial adhesion and subsequent surface degradation on commercial Ti, TiZr, and ZrO₂ implants. Methods: Ti, TiZr, and ZrO₂ implants with sandblasted, acid-etched (SLA) surfaces in addition to modified SLA-treated (modSLA) Ti implants (n = 3) were immersed for 30 consecutive days in Streptococcus polyculture. Post-immersion, adherent bacterial count was quantified. Optical microscopy was used to assess qualitative degradation and score Ti-based implants based on degree of surface damage while electrochemical testing quantified corrosion behavior. Analysis of variance followed by post-hoc Tukey test was used to statistically compare quantitative results (alpha = 0.05). Results: Ti-SLA, Ti-modSLA, and TiZr-SLA implants exhibited localized features characteristic of corrosion attack while ZrO₂-SLA implants experienced minimal changes in surface morphology as compared to non-immersed control. Corrosion features were more numerous on Ti-modSLA implants but smaller in size as compared with those on Ti-SLA and TiZr-SLA implants. No significant differences in corrosion resistance (polarization resistance and corrosion rate) were observed between Ti-SLA, Ti-modSLA, and TiZr-SLA implants. Conclusion: TiZr and ZrO₂ dental implant surfaces were not more susceptible to colonization and surface degradation by oral Streptococcus species than commercially pure Ti implants.Item Multifaceted Roles of Environmental Factors toward Dental Implant Performance: Observations from Clinical Retrievals and In Vitro Testing(Elsevier Inc.) Sridhar, Sathyanarayanan; Wang, Frederick; Wilson, T. G., Jr.; Valderrama, P.; Palmer, Kelli; Rodrigues, Danieli C.; Sridhar, Sathyanarayanan; Wang, Frederick; Palmer, Kelli; Rodrigues, Danieli C.Objective: Oral bacteria and periodontal pathogen have been predominantly linked with early- and late- stage failures of titanium (Ti) dental implants (DI) respectively. This study is based on the hypothesis that bacterial colonization can damage the surface oxide (TiO₂) layer. Early-failed DI were compared with DI post-in vitro immersion in early colonizing oral bacteria; late failed DI were weighed against DI immersed in late colonizing anaerobic pathogens. Methods: Retrieval analysis: Seven early- stage failed implants with five of them connected to healing abutments (HAs), and ten late- stage failed retrievals were subjected to surface analysis. Bacteria immersion test: Three dental implants each were immersed in polycultures containing (i) early colonizers (Streptococcus mutans, S. salivarius, S. sanguinis) (ii) late colonizers (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans). The implants were immersed for 30 days to simulate the healing period and bacterial biofilm adhesion. Optical microscope, x-ray photoelectron spectroscopy (XPS), and electrochemical test were performed to analyze the surface- morphology, chemistry, and potential respectively. Results: Early colonizers inflicted surface morphological damage (discoloration and pitting). Even though, XPS detected thinner oxide layer in 2/3 early retrievals, XPS and electrochemical tests illustrated that the TiO₂ layer was intact in HAs, and in DI post- immersion. Late colonizers also caused similar morphological damage (discoloration and pitting), while mechanical wear was evident with scratches, cracks, and mechanical fracture observed in late-stage retrievals. XPS indicated thinner oxide layer in late-stage retrievals (3/4), and in DI post-immersion in late colonizers. This was reflected in electrochemical test results post-immersion but not in the late-stage retrievals, which suggested an intact surface with corrosion resistance. Significance: This study concluded that bacteria could negatively affect implant surface with late colonizers demonstrating more pronounced damage on the surface morphology and chemistry. ©2018 The Academy of Dental Materials