Dental Implants with Anti-Biofilm Properties: A Pilot Study for Developing a New Sericin-Based Coating

Abstract

Aim: several strategies have been tested in recent years to prevent bacterial colonization of dental implants. Sericin, one of the two main silk proteins, possesses relevant biological activities and also literature reports about its potential antibacterial properties, but results are discordant and not yet definitive. The aim of this study was to evaluate the effectiveness of different experimental protocols in order to obtain a sericin-based coating on medical grade titanium (Ti) able to reduce microbial adhesion to the dental implant surface. Materials and Methods: different strategies for covalent bonding of sericin to Ti were pursued throughout a multi-step procedure on Ti-6Al-4V disks. The surface of grade 5 Ti was initially immersed in NaOH solution to obtain the exposure of functional -OH groups. Two different silanization strategies were then tested using aminopropyltriethoxysilane (APTES). Eventually, the bonding between silanized Ti-6Al-4V and sericin was obtained with two different crosslinking processes: glutaraldehyde (GLU) or carbodiimide/N-Hydroxy-succinimide (EDC/NHS). Micro-morphological and compositional analyses were performed on the samples at each intermediate step to assess the most effective coating strategy able to optimize the silanization and bioconjugation processes. Microbiological tests on the coated Ti-6Al-4V disks were conducted in vitro using a standard biofilm producer strain of Staphylococcus aureus (ATCC 6538) to quantify the inhibition of microbial biofilm formation (anti-biofilm efficacy) at 24 hours. Results: both silanization techniques resulted in a significant increase of silicon (Si) on the Ti-6Al-4V surfaces etched with NaOH. Differences were found between GLU and EDC/NHS bioconjugation strategies in terms of composition, surface micro-morphology and anti-biofilm efficacy. Ti-6Al-4V samples coated with GLU-bound sericin after silanization obtained via vapor phase deposition proved that this technique is the most convenient and effective coating strategy, resulting in a bacterial inhibition of about 53% in respect to the uncoated Ti-6Al-4V disks. Conclusions: The coating with glutaraldehyde-bound sericin after silanization in the vapor phase showed promising bacterial inhibition values with a significant reduction of S. aureus biofilm. Further studies including higher number of replicates and more peri-implant-relevant microorganisms are needed to evaluate the applicability of this experimental protocol to dental implants.

Biological Responses to the Transitional Area of Dental Implants: Material- and Structure-Dependent Responses of Peri-Implant Tissue to Abutments

“…Various technologies have been explored for improving the soft tissue seal at the transmucosal part of the abutment, including surface treatments, such as coating, machining, blasting, plasma spraying, etching, and laser processing [58].…”

Rhamnolipid Coating Reduces Microbial Biofilm Formation on Titanium Implants: an in-vitro Study

“…However, published studies are mainly focused on the evaluation of antimicrobial activity on planktonic cells [69,70]. A limited number of studies addressed the potential of rhamnolipid biosurfactants in preventing microbial adhesion and bio lm formation on conditioned surfaces [41,[71][72][73][74], and to our knowledge, this is the rst time that an anti-bio lm rhamnolipid-coating was applied on medical-grade titanium.…”

“…Laboratory polished discs were used for optimizing anti-bio lm coating (Phase 1) and evaluating the microbial inhibition e cacy along time (Phase 2). To remove impurities and grinding residues, laboratory polished TDs were cleaned by sonication for 15 min each in three consecutive solutions, 100% acetone, 70% v/v ethanol in distilled water and 100% distilled water, as indicated in Ghensi et al [41]. The discs were then disinfected by immersion for a minimum of 24 h in 70% v/v ethanol in water and stored in these conditions until further use.…”

Rhamnolipid coating reduces microbial biofilm formation on titanium implants: an in-vitro study

“…However, published studies are mainly focused on the evaluation of antimicrobial activity on planktonic cells [61,62]. A limited number of studies addressed the potential of rhamnolipid biosurfactants in preventing microbial adhesion and bio lm formation on conditioned surfaces [30,[63][64][65][66], and to our knowledge, this is the rst time that an anti-bio lm rhamnolipid-coating was applied on medical-grade titanium.…”

“…Laboratory polished discs were used for optimizing anti-bio lm coating (Phase 1) and evaluating the microbial inhibition e cacy along time (Phase 2). To remove impurities and grinding residues, laboratory polished TDs were cleaned by sonication for 15 min each in three consecutive solutions, 100% acetone, 70% v/v ethanol in distilled water and 100% distilled water, as indicated in Ghensi et al [30]. The discs were then disinfected by immersion for a minimum of 24 h in 70% v/v ethanol in water and stored in these conditions until further use.…”