Self-cleaning effects of acrylic resin containing fluoridated apatite-coated titanium dioxide.

OBJECTIVES: Specific materials when used in the manufacture of dentures can enhance the elimination of micro-organisms to promote oral hygiene. We used Candida albicans adhesion assays, methylene blue (MB)-decomposition tests and mechanical property tests to evaluate the photocatalytic properties of acrylic resin containing fluoridated apatite-coated titanium dioxide (FAp-TiO2 ) after treatment with ultraviolet A (UVA) irradiation. BACKGROUND: Conventional denture cleaning methods are unable to completely eliminate micro-organisms from dentures. MATERIALS AND METHODS: Test specimens were prepared using acrylic resin containing three types of TiO2 powder [FAp-TiO2, titanium dioxide (TiO2 ) and hydroxyapatite-coated TiO2 (HAp-TiO2 )]; n = 96. In the adhesion assay, test specimens were incubated in a fungal suspension and subjected to UVA irradiation, and the number of attachments of C. albicans on the test specimens was counted. The MB-decomposition test and the three-point bending test were then performed to assess the photocatalytic effects of the FAp-TiO2 -containing acrylic resin. RESULTS: Fluoridated apatite-coated titanium dioxide-containing acrylic resin demonstrated superior effectiveness in inhibiting C. albicans adherence as well as in decomposing MB. In the three-point bending test, the resin showed a smaller decrease in flexural strength compared with TiO2 - or HAp-TiO2 -containing acrylic resin. Furthermore, UVA irradiation for 360 h did not significantly influence its flexural strength or elasticity modulus as compared with the control; this fulfils the requirements of International Organization for Standardization 1567:1999. CONCLUSION: Fluoridated apatite-coated titanium dioxide-containing acrylic resin is a clinically suitable material that promotes proper denture hygiene, particularly for elderly persons requiring nursing care or who have a decreased ability to perform normal activities of daily living.

ESR detection of ROS generated by TiO2 coated with fluoridated apatite.

Specific materials used in the manufacture of dentures may enhance the removal of micro-organisms. The ultraviolet A (UVA) irradiation of acrylic resin containing titanium dioxide (TiO(2)) generates reactive oxygen species (ROS) by photocatalysis that shows antibacterial effects. In this study, we tested the hypothesis that TiO(2) coated with fluoridated apatite (FAp-TiO(2)) can generate ROS via photo-catalysis by using electron spin resonance (ESR), and that acrylic resin containing FAp-TiO(2) can show antifungal properties by measuring the viability of Candida albicans. We demonstrated that hydroxyl radicals (HO(*)) were generated through excitation of TiO(2), TiO(2) coated with apatite (HAp-TiO(2)), and FAp-TiO(2). The HO(*) generation through excitation of FAp-TiO(2) was higher than that of TiO(2) and HAp-TiO(2). Regarding antifungal activity, cell viability on acrylic resin containing FAp-TiO(2) was lower than that of TiO(2) and HAp-TiO(2). FAp-TiO(2) showed superior photocatalytic effects, and these characteristics may lead to novel methods for the clinical application of denture-cleaning treatments.

Antifungal effect of acrylic resin containing apatite-coated TiO2 photocatalyst.

The purpose of this study was to develop an acrylic resin with antifungal properties by leveraging the photocatalytic activity of apatite-coated titanium dioxide (Ap-TiO2). Candida albicans was used for antifungal activity assay of the specimen plates under ultraviolet A (UVA) with a black light source. Statistically significant decreases in cell viability in acrylic resins containing 5 wt% and 10 wt% Ap-TiO2 were observed after irradiation for two, four, and six hours (P<0.01), when compared to the control. As for the flexural strength and modulus values of acrylic resins mixed with Ap-TiO2 and TiO2 particles, they varied before and after irradiation. Among the tested specimens, a 5 wt% content of Ap-TiO2 in acrylic resin exceeded the requirements of ISO 1567. It was thus suggested that acrylic resin containing 5 wt% Ap-TiO2 could exert antifungal effects on C. albicans, while at the same time maintain adequate mechanical properties for clinical use.

Shear bond strength of veneering composite resin to titanium nitride coating alloy deposited by radiofrequency sputtering.

OBJECTIVE: The success of dental restorations utilizing composite resin over cast alloy has been variable and affected by micro-leakage. The purpose of this study was to investigate the shear bond strength between a composite resin and cast dental alloy coated with a layer of titanium nitride (TiN). METHODS: Cast disk specimens made of Au-Pd-Ag alloy were randomly divided into four groups. The first group was left uncoated as a control while one group was coated with a metal conditioner, and the other two were coated with TiN at either 200 or 500 W with a radiofrequency magnetron sputtering system. Each group was then bonded to one of two types of light-activated composite resin material. Shear bond strengths were tested and compared for each specimen. The bond strength of each group was analyzed by 2-way ANOVA and by post hoc multiple comparison tests (Fisher's PLSD). RESULTS: As the interaction among groups was not significant (p=0.27) by 2-way ANOVA, TiN coated groups were found to have improved shear bond strength compared with non-coated groups without metal conditioner for both resin composite materials by multiple comparison tests. Furthermore, TiN coating is significantly stronger than non-coated groups with metal conditioner for one of the two resin composite materials examined (p<0.01). CONCLUSIONS: The results suggested that metal surface modification by coated TiN represents a technique that may significantly improve the bond between the Au-Pd-Ag alloy and veneering resin composite.