Study of the Electronic Interaction between NiO and Short Polythiophene Chains towards Solar Photon Harvesting.

The sustainable production of energy is a field of interest to which a new requirement is now imposed: the need to be respectful of the environment. New materials and techniques are being developed, but environmental concerns impose the necessity of keeping research active towards the development of green energy. For this reason, we present the study of short polythiophene (PTh) chains (three and five monomers) and their interaction with nickel oxide, looking for properties related to solar photon harvesting in order to produce electricity. The models of the molecules were developed, and the calculations were performed with an M11-L meta-GGA functional, specially developed for electronic structure calculations. The theoretical explorations demonstrated that the geometry of the PTh molecules suffer little distortion when interacting with the NiO molecule. The calculated value of Eg lies between 2.500 and 0.412 eV for a three-ring PTh chain and between 1.944 and 0.556 eV for a five-ring PTh chain. The chemical parameters indicated that, depending on the geometry of the system, the chemical potential varies from 81.27 to 102.38 kcal/mol and the highest amount of electronic charge varies from -2.94 to 21.56 a.u. for three-monomer systems. For five-monomer systems, the values lie within similar ranges as those of the three-monomer systems. The Partial Density of States (PDOS) showed that the valence and conduction electronic bands were composed of states in the NiO and PTh rings, except for a system where there was a non-bonding interaction.

Two-year clinical performance of Clearfil SE and Clearfil S3 in restoration of unabraded non-carious class V lesions.

This study was undertaken to evaluate the two-year clinical performance of a self-etching primer and a self-etching adhesive, both of which employ the same acidic monomer. Forty pairs of restorations of AP-X hybrid resin composite (Kuraray Co, Ltd, Osaka, Japan) were placed in caries-free cervical erosion/abfraction lesions. Based on insensitivity to air, the dentin in 62% of these lesions was considered to be sclerotic. The restorations were placed with no abrasion of tooth surfaces, except for cleaning with plain pumice and no use of phosphoric acid etching, which is counter to the manufacturer's instructions that call for etching of unprepared enamel. One restoration from each pair was placed using Clearfil SE Bond, an adhesive employing a self-etching primer, and the other was placed using Clearfil S3 Bond, a self-etching adhesive. To emulate the results likely to occur in a private practice, the restorations were placed by well-educated, experienced clinicians who had no particular expertise in adhesive dentistry research and who placed the restorations according only to their interpretation of the manufacturer's instructions. The restorations were clinically evaluated at baseline and at 6, 12 and 24 months, using modified Ryge/USPHS criteria. For both products, retention of 81%-84% of the restorations was observed over two years, which is lower than has been previously observed with these products and is likely due to limitations in the manufacturer's instructions compounded by inexperience of the operators in adhesive dentistry research. One restoration placed with each adhesive demonstrated secondary caries, which was probably attributable to the study being conducted in a non-fluoridated area and which reduced the percentages of clinically successful restorations to 78%-81%. No statistically significant difference (p = 0.50) between the two adhesives was observed in overall performance.

Eighteen-month clinical performance of a self-etching primer in unprepared class V resin restorations.

This study evaluated the clinical performance of unprepared Class V resin composites, placed using a self-etching primer and a single-bottle adhesive, over a period of 18 months. Thirty-eight pairs of restorations of Renew hybrid resin composite (BISCO, Inc) were placed using adhesives from the same manufacturer in caries-free cervical erosion/abfraction lesions. Based on insensitivity to air, the dentin in 76% of these lesions was considered to be sclerotic. The restorations were placed without abrasion of tooth surfaces, except for cleaning with plain pumice. One of each pair was placed using Tyrian, a self-etching primer and the other was placed using One-Step, a single-bottle adhesive placed after acid etching. Both the etchant and self-etching primer were applied for 20 seconds. The restorations were clinically evaluated at baseline, 6, 12 and 18 months, using modified Ryge/USPHS criteria. For both adhesives, very low retention of 50% to 56% of the restorations was observed over 18 months, leading to the conclusion that tooth surfaces must receive some additional treatment prior to restoration with these adhesives. No statistically significant difference (p=0.75) between the two adhesives was observed in overall performance, and dentinal sclerosis and axial depth did not appear to be important factors in the study.