Effects of Photodynamic Process (PDP) in Implant Osseointegration: A Histologic and Histometric Study in Dogs

The current status of stimuli-responsive nanotechnologies on orthopedic titanium implant surfaces

With the continuous innovation and breakthrough of nanomedical technology, stimuli-responsive nanotechnology has been gradually applied to the surface modification of titanium implants to achieve brilliant antibacterial activity and promoted osteogenesis. Regarding to the different physiological and pathological microenvironment around implants before and after surgery, these surface nanomodifications are designed to respond to different stimuli and environmental changes in a timely, efficient, and specific way/manner. Here, we focus on the materials related to stimuli-responsive nanotechnology on titanium implant surface modification, including metals and their compounds, polymer materials and other materials. In addition, the mechanism of different response types is introduced according to different activation stimuli, including magnetic, electrical, photic, radio frequency and ultrasonic stimuli, pH and enzymatic stimuli (the internal stimuli). Meanwhile, the associated functions, potential applications and developing prospect were discussion.

Nanotechnology for Dentistry: Prospects and Applications

In the XXI century, application of nanostructures in oral medicine has become common. In oral medicine, using nanostructures for the treatment of dental caries constitutes a great challenge. There are extensive studies on the implementation of nanomaterials to dental composites in order to improve their properties, e.g., their adhesive strength. Moreover, nanostructures are helpful in dental implant applications as well as in maxillofacial surgery for accelerated healing, promoting osseointegration, and others. Dental personal care products are an important part of oral medicine where nanomaterials are increasingly used, e.g., toothpaste for hypersensitivity. Nowadays, nanoparticles such as macrocycles are used in different formulations for early cancer diagnosis in the oral area. Cancer of the oral cavity-human squamous carcinoma-is the sixth leading cause of death. Detection in the early stage offers the best chance at total cure. Along with diagnosis, macrocycles are used for photodynamic mechanism-based treatments, which possess many advantages, such as protecting healthy tissues and producing good cosmetic results. Application of nanostructures in medicine carries potential risks, like long-term influence of toxicity on body, which need to be studied further. The introduction and development of nanotechnologies and nanomaterials are no longer part of a hypothetical future, but an increasingly important element of today's medicine.

Innovative Concepts and Recent Breakthrough for Engineered Graft and Constructs for Bone Regeneration: A Literature Systematic Review

Background: For decades, regenerative medicine and dentistry have been improved with new therapies and innovative clinical protocols. The aim of the present investigation was to evaluate through a critical review the recent innovations in the field of bone regeneration with a focus on the healing potentials and clinical protocols of bone substitutes combined with engineered constructs, growth factors and photobiomodulation applications. Methods: A Boolean systematic search was conducted by PubMed/Medline, PubMed/Central, Web of Science and Google scholar databases according to the PRISMA guidelines. Results: After the initial screening, a total of 304 papers were considered eligible for the qualitative synthesis. The articles included were categorized according to the main topics: alloplastic bone substitutes, autologous teeth derived substitutes, xenografts, platelet-derived concentrates, laser therapy, microbiota and bone metabolism and mesenchymal cells construct. Conclusions: The effectiveness of the present investigation showed that the use of biocompatible and bio-resorbable bone substitutes are related to the high-predictability of the bone regeneration protocols, while the oral microbiota and systemic health of the patient produce a clinical advantage for the long-term success of the regeneration procedures and implant-supported restorations. The use of growth factors is able to reduce the co-morbidity of the regenerative procedure ameliorating the post-operative healing phase. The LLLT is an adjuvant protocol to improve the soft and hard tissues response for bone regeneration treatment protocols.

Antimicrobial Photodynamic Therapy (aPDT) as a Disinfection and Biomodulation Approach in Implant Dentistry

This article is a highlight of the paper by Choe et al. in this issue of Photochemistry and Photobiology. In that review paper, the disinfection and biomodulation outcomes promoted by antimicrobial photodynamic therapy (aPDT) on peri-implantitis infection were stated and discussed. The killing of the oral pathogens by aPDT is based on the generation of reactive oxygen species (ROS). Besides that, biomodulation can also be provided by aPDT and improve the healing and modulate the inflammatory process. Although aPDT has shown positive effects on the treatment of peri-implantitis disease mainly as a complimentary technique, the authors suggested that more and standardize clinical studies are needed to support the clinical application of aPDT for that purpose. Also, the standardization of parameters related to the light source and photosensitizers is required. In addition, nano-based materials may improve aPDT performance against oral biofilms and could increase the hopes of overcoming dental implant failures.

Photodynamic Therapy for Biomodulation and Disinfection in Implant Dentistry: Is It Feasible and Effective?

Dental implants are the most common rehabilitation and restorative treatment used to replace missing teeth. Biofilms adhere to implant surfaces to trigger implant-associated infection and inflammatory response. Clinically, the biofilm induces a local host response with the infiltration of phagocytic immune cells. The pro-inflammatory surroundings set off osteoclastogenesis, which leads to the septic loosening of the implant. The standard of dental care for implant-associated infection relies on a combination of surgery and antimicrobial therapy. Antimicrobial photodynamic therapy is a noninvasive and photochemistry-based approach capable of reducing bacterial load and modulating inflammatory responses. In this review, we explore the photobiomodulation and disinfection outcomes promoted by photodynamic therapy for implant infections, highlighting the quality of evidence on the most up-to-date studies, and discuss the major challenges on the advance of these therapeutic strategies.

Phthalocyanine-loaded nanostructured lipid carriers functionalized with folic acid for photodynamic therapy

Breast cancer is a serious public health problem that causes thousands of deaths annually. Chemotherapy continues to play a central role in the management of breast cancer but is associated with extreme off-target toxicity. Therefore, treatments that directly target the tumor and display reduced susceptibility to resistance could improve the outcome and quality of life for patients suffering from this disease. Photodynamic therapy is a targeted treatment based on the use of light to activate a photosensitizer (PS) that then interacts with molecular oxygen and other biochemical substrates to generate cytotoxic levels of Reactive Oxygen Species. Currently approved PS also tends to have poor aqueous solubility that can cause problems when delivered intravenously. In order to circumvent this limitation, in this manuscript, we evaluate the potential of a phthalocyanine-loaded nanostructured lipid carrier (NLC) functionalized with folic acid (FA). To prepare the FA labelled NLC, the polymer PF127 was first esterified with FA and emulsified with an oil phase containing polyoxyethylene 40 stearate, capric/caprylic acid triglycerides, ethoxylated hydrogenated castor oil 40 and the PS zinc phthalocyanine. The resulting PS loaded FA-NLC had a hydrodynamic diameter of 180 nm and were stable in suspension for >90 days. Interestingly, the amount of singlet oxygen generated upon light activation for the PS loaded FA-NLC was substantially higher than the free PS, yet at a lower PS concentration. The PS was released from the NLC in a sustained manner with 4.13 ± 0.58% and 27.7 ± 3.16% after 30 min and 7 days, respectively. Finally, cytotoxicity assays showed that NLC in the concentrations of 09.1 μM of PS present non-toxic with >80 ± 6.8% viable and after 90 s of the light-exposed the results show a statistically significant decrease in cell viability (57 ± 4%). The results obtained allow us to conclude that the functionalized NLC incorporated with PS associated with the PDT technique have characteristics that make them potential candidates for the alternative treatment of breast cancer.

Inactivation of oral biofilms using visible light and water-filtered infrared A radiation and indocyanine green

Aim: To investigate the antimicrobial photodynamic therapy (aPDT) of visible light and water-filtered infrared A radiation in combination with indocyanine green (ICG) on planktonic oral microorganisms as well as on oral biofilm. Methods: The irradiation was conducted for 5 min in combination with ICG. Treatment with chlorhexidine served as a positive control. The number of colony forming units and bacterial vitality were quantified. Results: All tested bacterial strains and salivary bacteria were killed at a level of 3log_10. The colony forming units of the initial mature oral biofilms were strongly reduced. The high bactericidal effect of aPDT was confirmed by live/dead staining. Conclusion: The aPDT using visible light and water-filtered infrared A radiation and ICG has the potential to treat periodontitis and peri-implantitis.

Biomedical applications of nanotechnology

The ability to investigate substances at the molecular level has boosted the search for materials with outstanding properties for use in medicine. The application of these novel materials has generated the new research field of nanobiotechnology, which plays a central role in disease diagnosis, drug design and delivery, and implants. In this review, we provide an overview of the use of metallic and metal oxide nanoparticles, carbon-nanotubes, liposomes, and nanopatterned flat surfaces for specific biomedical applications. The chemical and physical properties of the surface of these materials allow their use in diagnosis, biosensing and bioimaging devices, drug delivery systems, and bone substitute implants. The toxicology of these particles is also discussed in the light of a new field referred to as nanotoxicology that studies the surface effects emerging from nanostructured materials.

Liposomal systems as carriers for bioactive compounds

Since the revolutionary discovery that phospholipids can form closed bilayered structures in aqueous systems, the study of liposomes has become a very interesting area of research. The versatility and amazing biocompatibility of liposomes has resulted in their wide-spread use in many scientific fields, and many of their applications, especially in medicine, have yielded breakthroughs in recent decades. Specifically, their easy preparation and various structural aspects have given rise to broadly usable methodologies to internalize different compounds, with either lipophilic or hydrophilic properties. The study of compounds with potential biotechnological application(s) is generally related to evaluation and risk assessment of the possible cytotoxic or therapeutic effects of the compound under study. In most cases, undesirable side-effects are associated with an interaction of the liposome with the cell membrane and/or its absorption and subsequent interaction with a cellular biomolecule. Liposomal carrier systems have an unprecedented potential for delivering bioactive substances to specific molecular targets due to their biocompatibility, biodegradability and low toxicity. Liposomes are therefore considered to be an invaluable asset in applied biotechnology studies due to their potential for interaction with both hydrophilic and lipophilic compounds.