Early Biofilm Formation on UV Light Activated Nanoporous TiO2 Surfaces In Vivo

Fitting pieces into the puzzle: The impact of titanium-based dental implant surface modifications on bacterial accumulation and polymicrobial infections

Polymicrobial infection is the main cause of dental implant failure. Although numerous studies have reported the ability of titanium (Ti) surface modifications to inhibit microbial adhesion and biofilm accumulation, the majority of solutions for the utilization of Ti antibacterial surfaces have been testedin in vitro and animal models, with only a few developed surfaces progressing into clinical research. Motivated by this huge gap, we critically reviewed the scientific literature on the existing antibacterial Ti surfaces to help understand these surfaces' impact on the "puzzle" of undesirable dental implant-related infections. This manuscript comprises three main sections: (i) a narrative review on topics related to oral biofilm formation, bacterial-implant surface interactions, and on how implant-surface modifications can influence microbial accumulation; (ii) a critical evidence-based review to summarize pre-clinical and clinical studies in an attempt to "fit pieces into the puzzle" to unveil the best way to reduce microbial loads and control polymicrobial infection around dental implants showed by the current in vivo evidence; and (iii) discussion and recommendations for future research testing emerging antibacterial implant surfaces, connecting basic science and the requirements for future clinical translation. The findings of the present review suggest no consensus regarding the best available Ti surface to reduce bacterial colonization on dental implants. Smart release or on-demand activation surface coatings are a "new piece of the puzzle", which may be the most effective alternative for reducing microbial colonization on Ti surfaces, and future studies should focus on these technologies.

Organotypic in vitro block culture model to investigate tissue-implant interface. An experimental study on pig mandible

In vitro studies of implant-tissue attachment are primarily based on two-dimensional cell culture models, which fail to replicate the three-dimensional native human oral mucosal tissue completely. Thus, the present study aimed to describe a novel tissue culture model using pig mandibular block including alveolar bone and gingival soft tissues to evaluate the tissue attachment to titanium implant provided with hydrothermally induced TiO₂ coating. Tissue attachment on TiO₂ coated and non-coated implants were compared. Ti-6Al-4V alloy posts were used to function as implants that were inserted in five pig mandibles. Implants were delivered with two different surface treatments, non-coated (NC) titanium and hydrothermal induced TiO₂ coated surfaces (HT). The tissue-implant specimens were cultured at an air/liquid interface for 7 and 14 days. The tissue-implant interface was analyzed by histological and immunohistochemical stainings. The microscopic evaluation suggests that pig tissue explants established soft and hard tissue attachment to both implant surfaces. The epithelial cells appeared to attach to the coated implant. The epithelium adjacent to the implant abutment starts to change its phenotype during the early days of the healing process. New bone formation was seen within small pieces of bone in close contact with the coated implant. In conclusion, this in vitro model maintains the viability of pig tissue and allows histologically and immunohistochemically evaluate the tissue-implant interface. HT-induced TiO₂ coating seems to have a favorable tissue response. Moreover, this organotypic tissue culture model is applicable for further studies with quantitative parameters to evaluate adhesion molecules present at the implant-tissue interface.

The influence of nanoporous anodic aluminum oxide on the initial adhesion of Streptococcus mitis and mutans

The use of nanoscale surface modifications offers a possibility to regulate the bacterial adherence behavior. The aim of this study was to evaluate the influence of nanoporous anodic aluminum oxide of different pore diameters on the bacterial species Streptococcus mitis and Streptococcus mutans. Nanoporous anodic aluminum oxide (AAO) surfaces with an average pore diameter of 15 and 40 nm, polished pure titanium and compact aluminum oxide (alumina) samples as reference material were investigated. S. mitis and mutans were evaluated for initial adhesion and viability after an incubation period of 30 and 120 min. After 30 min a significantly reduced growth of S. mitis and mutans on 15 nm samples compared to specimens with 40 nm pore diameter, alumina and titanium surfaces could be observed (p < .001). Even after 120 min incubation there was a significant difference between the surfaces with 15 nm pore diameter and the remaining samples (p < .001). AAO surfaces with a small pore diameter have an inhibitory effect on the initial adhesion of S. mitis and mutans. The use of such pore dimensions in the area of the implant shoulder represents a possibility to reduce the adhesion behavior of these bacterial species.