Assessment of anodized titanium implants bioactivity.

OBJECTIVES: This study was conducted to create nanostructured surface titanium implants by anodic oxidation process aiming to bring out bioactivity and to assess the resultant bioactivity both in vitro and in vivo. MATERIALS AND METHODS: An economic protocol was used to apply anodic spark discharge and create surface nanoporosities on grade II commercially pure titanium (cpTi). The in vitro investigation included morphology, surface chemical analysis, roughness and crystalline structure of titanium oxide (TiO2) film prepared. Assessment of the bioactivity was carried out by immersing the specimens in simulate body fluid (SBF) and investigating the surface-deposited layer. The in vivo investigation was conducted by surgically placing the anodized implants into rabbits tibia for different healing periods. Then biomechanical evaluation was performed to verify the effect of treatments on the interface resistance to shear force. Routine histological analysis was performed to evaluate the bone tissue reactions to anodized implants. RESULTS: Anodization of titanium implants produced morphological changes, raised the percentage of oxygen in the TiO2 layer, increased surface area and roughness of implants remarkably, and modified the crystallinity of the film. The in vitro assessments of bioactivity showed that a layer of calcium phosphate was precipitated on the titanium surfaces 7 days after soaking into SBF. The implant-bone interface resistance to shear force was enhanced at 2-week healing period. This was confirmed by histological findings. CONCLUSION: Nanostructured surface titanium implants could be prepared by anodic oxidation with resultant accelerated bioactivity that may be recommended for early loading.

Effect of light-curing method on wear and hardness of composite resin.

The primary aims of this study is to determine the wear and microhardness of composite resin cured with a light emitting diode (LED) and to make a comparison with a conventional halogen light curing unit (VLC LCU). The effect of load on weight loss was also investigated. For the wear tests, composite specimens were prepared in a rectangular mold. Specimens were divided into 5 groups; the first three groups were polymerized with LED LCU for 10, 20, and 40 s. Groups 4 and 5 were polymerized with VLC LCU for 20 and 40 s. Each group was divided into 2 subgroups according to the wearing loads (60 N and 90 N). Weight loss was recorded using a conventional Tribometer (mg). Specimens cured using LED showed greater hardness and less wear compared to conventional VLC-cured specimens under comparable test conditions. The improved wear resistance of LED-cured material-demonstrated here for the first time-suggests significant advantages for clinical practice.

Reinforcement of conventional glass-ionomer restorative material with short glass fibers.

This study investigated the strengthening effect of glass fibers when added to conventional glass-ionomer restorative material. Glass fibers were incorporated into glass-ionomer powder in 3 wt% and 5 wt%. The fibers used had 1 mm length and 10 microm thickness. These criteria of fiber length, diameter, and concentration represent a new approach for reinforcing conventional glass-ionomer [Medifill, conventional restorative glass-ionomer]. The mechanical properties tested were diametral tensile strength, hardness, flexural strength, flexural modulus and fracture toughness after 24-h and 7-days of storage in deionized water. Glass short fibers were mixed thoroughly into the glass-ionomer powder before mixing with the cement liquid. Samples of specific dimensions were prepared for each time interval and fiber loading according to the manufacturer's instructions and international standards. Hardness was measured using a micro-hardness tester at 100 gram applied load for 15 s. The other mechanical properties were measured using a Lloyd universal testing machine. The results showed increased diametral tensile strength, flexural strength, flexural modulus, and fracture toughness by the addition of glass fibers. There was an appreciable increase of the tested mechanical properties of glass-ionomer restorative material as a result of increasing fiber loading and water storage for 1 week. It was concluded that conventional glass-ionomer can be reinforced by the addition of short glass fibers.