Incorporation of TiO(2) and SiO(2) nanoparticles into acrylic resins can adversely affect the flexural strength of the final products, and this effect is directly correlated with the concentration of nanoparticles.

Phototherapy began in ancient Egypt. Ancient Egyptians treated some skin diseases with herbs and sunlight. They applied natural photosensitizers such as psoralens (extracted from particular plants such as Parsley and Stjohn's-wort) for treatment of leprosy lesions 1, 2). Osar Raab, a medical student who worked in Munich was the first one to notice that dyes like acrydine along with light can kill paramecia. He discovered that the incubation of paramecium with acridine and consequent exposure to light potentially kills paramecium. However, the mere application of acridine without light exposure was not effective 3). In following years, Von Tappeiner coined the term "photodynamic action" and attested that the presence of oxygen is essential in photodynamic action. The first PDT was performed on a patient with skin carcinoma. It was carried out by T. Appaeiner and H. Jesionek in 1904. They used Eosin as PS along with white light. In recent years, more advances have been made in anticancer photodynamic therapy and different PSs are discovered 1, 2, 4, 5). Antibacterial Photodynamic Therapy (APDT) was first introduced in 1960. Macmillan used toluidine blue against microorganisms like bacteria, algae, and yeast. It was observed that 99% of bacteria were killed within 30 min of irradiation with 21-30 mW of light at 632 nm from

Introduction: Plaque accumulation and bond failure are drawbacks of orthodontic treatment, which requires composite for bonding of brackets. As the antimicrobial properties of TiO2 nanoparticles (NPs) have been proven, the aim of this study was to evaluate the antimicrobial and mechanical properties of composite resins modified by the addition of TiO2 NPs. Methods: Orthodontics composite containing 0%, 1%, 5% and 10% NPs were prepared. 180 composite disks were prepared for elution test, disk agar diffusion test and biofilm inhibition test to collect the counts of microorganisms on three days, measure the inhibition diameter and quantify the viable counts of colonies consequently. For shear bond strength (SBS) test, 48 intact bovine incisors were divided into four groups. Composites containing 0%, 1%, 5% and 10% NPs were used for bonding of bracket. The bracket/tooth SBS was measured by using an universal testing machine. Results: All concentration of TiO2 NPs had a significant effect on creation and extension of inhibition zone. For S. mutans and S. sanguinis, all concentration of TiO2 NPs caused reduction of the colony counts. Composite containing 10% TiO2 NPs had significant effect on reduction of colony counts for S. mutans and S. sanguinis in all three days. The highest mean shear bond strength belonged to the control group, while the lowest value was seen in 10% NPs composite. Conclusions: Incorporating TiO2 nanoparticles into composite resins confer antibacterial properties to adhesives, while the mean shear bond of composite containing 1% and 5% NPs still in an acceptable range.

Many polymeric materials have been developed and introduced for bone regeneration. Especially, their nanofibrous forms are mostly applied for artificial extracellular matrices. Polymeric materials in their nanofibrous form show some potent properties such as high surface-to-volume ratio, tunable porosity, and ease of surface functionalization. Benefiting from the properties of their main polymer and additives, they can provide new opportunities for cell seeding, proliferation, and new 3D-tissue formation. This article focuses on most cited polymeric nanofibrous scaffolds fabricated by electrospinning and recent achievements. They were divided into two main categories: natural (collagen, silk, keratin, gelatin, chitosan, and alginate) and synthetic (e.g., polycaprolactone, polylactic acid, and polyglycolic acid) polymers. The role of several additives like hydroxyapatite, bone morphogenetic proteins (BMPs), tricalcium phosphate, and collagen type I in improving the adhesion, differentiation, and tissue formation of stem cells were discussed. Finally, the osteogenic capacity and ability of nanofibrous scaffolds to support the growth of clinically relevant bone tissue were briefly studied.

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