1. Introduction:
Titanium alloys are very reactive materials and reacts instaneusely with oxygen, forming an oxide film, which give them excellent anti corrosive properties [??]. Thus, titanium alloys have proven to be the most tissue compatible inorganic materials, especially for dentistry [???].
Nickel-titanium wires, which have a near equiatomic composition, were introduced to orthodontic clinical use by Andersen and colleagues in the early 1970’s [???]. They have been highly popular in dentistry because have a much lower elastic modulus and wider elastic range than other orthodontic wires such as those composed of beta-titanium, stainless steel, and cobalt-chromium-nickel [???]. NiTi alloys have excellent biocompatibility with living tissue and corrosion resistance in various simulated body fluids [???]. These properties originating from the spontaneously formed thin oxide passivation layer mainly consist of TiO2 [???].
For patients with orthodontic fixed appliance, mouth rinsing with fluoride-containing products is an effective method for the prevention of caries because such appliances have complicated morphologies [???]. However, reduced corrosion resistance of pure titanium and titanium alloys in fluoride containing environments that attack the protective surface oxide layer and cause allergic reactions to NiTi wires after insertion had been reported [????]. The corrosion resistance of pure titanium and titanium alloys largely depends on the fluoride concentrations [???]. Some studies concerning the corrosion behavior of titanium alloys in fluoride containing environments have been reported [????]. It is claimed that the fluoride containing solution with fluoride ions more than 20 ppm may destroy the protective oxide la...
... middle of paper ...
...tive layer increases.
5. Conclusions
The corrosion resistance of NiTi was studied in ringer’s solution for different chloride ion concentrations. Our results show that the increasing of the chloride ion concentration can accelerate the corrosion of NiTi alloy. The OCP values in KCl and NaCl contained solutions are less negative at lower concentrations than in higher ones and the resistance to corrosion decreases as the chloride concentration increases. According to the EIS analysis, NiTi presents a good corrosion resistance even at higher concentration of chloride ions but the polarization resistance and capacitance value of protective oxide layer decreases as the concentration of ions increases.
Acknowledgements
The author acknowledges the Shiraz University, school of materials science and engineering for the financial supports. (Grant No. 89-GR-Eng-58)
We often say how lucky we are to live in a place where we have access to safe water at any time but what if that was questioned? What if our water isn’t safe; it’s just that now we can’t see the dangers? Throughout the world 25 first world countries fluoridate some amount of their water artificially; almost half of these countries have the majority of their population drinking this chemically enhanced liquid every single day. In the UK 11% of us only have access to fluoridated water [70% in Ireland], and in the USA its 60%. After a quick browse on Google, the information about fluoride that can be learned from the NHS is mainly about teeth and tooth decay as fluoride is put in our toothpaste due to its claimed abilities to help tooth enamel fight attack [nothing has ever alluded to supporting this claim]. What can’t be seen at
Thesis Statement: Concerns for water fluoridation stem from the toxicity of fluoride, the dangers fluoride pose to the body, and equal declining tooth decay seen for fluoridated and non-fluoridated countries.
Titanium and its alloys are used in various applications due to their desirable properties. One of the main sectors where titanium is highly used is in biomedical applications where both implants and tools for surgery make use of this element due to its biocompatibility, low modulus and excellent corrosion resistance. However titanium shows poor tribological properties and therefore it is generally alloyed and undergoes a surface modification to obtain the optimum requirements needed. Biomedical implants are subjected to high clinical requirements, hence before implantation in the human body, a surface modification process is carried out. The aim of carrying such modifications include; to sterilize the implant surface form contaminants before implantation, to increase the bioactivity, increase hardness and hence promotes the reduction in the implant wear rate and the introduction of a passive layer to minimize the ion release in the body.1
Metal alloys and precious metals are also used to make certain aspects of a cochlear implant. The electrode arrays that provide electrical stimulation in order to excite neurons are made out of platinum because they have very high corrosion resistance, good biocompatibility, easier to work with than iridium and have low chemical reactivity. On the other hand, metallic alloys like titanium are used to make the casing for the receiver/stimulator. Titanium is suitable for such an application because it is a light material with high corrosion resistance and rigidity and these properties are essential for the material that is going to be used to make the casing (Stöverl and Lenarz, 2009).
Improper nutrition and misbalance in our body may be the causes for tooth decay. Always pay attention to your nutrition when your teeth are considered, instead of choosing fluoride or dentistry. Our health can also be in danger when fluoride is used, even though the main reason for using fluoride is to make the teeth stronger. According to a recent study, mental disabilities are often made more difficult with the usage of fluoride. Among fluoride, mercury and arsenic are also dangerous in cases of autism
The purpose of this paper is to research the efficacy of silver diamine fluoride in comparison to sodium fluoride varnish. Our PICO question is: In a patient with dentinal caries, will the use of silver diamine fluoride compared to sodium fluoride varnish, be more effective at arresting caries? Fluoride has been established for many years as an effective ingredient in the fight against caries. Silver has been used in health care as an anti-bacterial agent in many medical applications such as silver sutures and silver catheters. Silver diamine fluoride was created to increase the effectiveness of both.
These kinds of polymers have both some advantages and disadvantages. Although they are bioactive and biodegradable and provide high comppressive strength, Degradation of such polymers leads to undesired tissue response due to producing acid formation in degradation process. Metallic scaffolds are another method for bone repair and regenaration. They provide high compressive strength and enormous permanent strength. Metallic scaffolds are mainly made of titanium and talium metals. The main disadvantages of metallic scaffolds are not biodegradable and also discharge metal ions. Recent studies in metallic scaffolds mainly focus on biodegradable materials which can be used improve bioactivity of metals such as titanium.
Titanium dioxide, also known as Titanium (IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it is sourced from ilminite, rutile and anatase. It has a wide range of applications, from paint to sunscreen to food colouring.
Seventy percent of the US population now receives fluoridated drinking water, an industrial grade level chemical most commonly associated with the prevention of tooth decay, and in Virginia especially, 95.7% of all public water is fluoridated (CDC). I present this numbers to your concern because for something that is almost in all public drinking water, it is not informed to the average Virginia citizen, but that is not the primary issue I am addressing you for. My main matter of concern is that more recent studies performed by scientist in the US and abroad are now finally advocating decade old cautions back then just acknowledged as unsubstantial research or even myths on how rather potentially hazardous the fluoridation of water is for
Dental composites are widely used for crown preparation and in-lays formation. These materials are similar to those used in direct fillings and are tooth-colored. Their strength and durability is not as high as porcelain or metal restorations and they are more
In conclusion, its recommended that patients brush two-three times a day two minutes long to insure that most of the bacteria is removed from the teeth,gums, and tongue also. Flossing after every meal should also be done regularly because of left foods that get stuck between the teeth. There are many kinds of toothpaste, but not all contain fluorine. Its important that you chose on that does have fluorine because it rebuild tooth enamel and strengthen the tooth too.
All water sources, whether fresh or salt, have varying levels of fluoride (Awofeso, 2012). Around 1945 it was discovered that communities with higher rates of naturally occurring fluoride had lower rates of tooth decay (Dean, 1938) which resulted in the addition of artificial fluoride to public water supplies. The incidence of tooth decay fell drastically in fluoridated communities as a result, leading to widespread adoption of public water fluoridation as a public health strategy.
...mpositional control needed and also the reactivity of the titanium. Fatigue failure has been known to occur with nitinol because of the extreme amounts of fatigue strain that it is necessarily exposed to. This is because it is still not completely defined how durable nitinol is, so it cannot be known what to use it for as it is the best of all metals known in this case. So it is used for the highest demanding applications but in some cases it can’t handle the pressure sustained. Another use for nitinol is a temperature control system, which would work by changing shape can activate a variable resistor or switch which would control the temperature, this is a situation where it is very significant for nitinol to be a smart material otherwise this system would simply just not work. There are many others but they are not really relevant to the engineering industry.
Our analysis revealed that Affinis® had more dimensional stability in comparison to Panasil® and in the Panasil® impression material, the percentage of dimensional change was significant after 168 h. However, dimensional changes in all of the evaluation times were in the American Dental Association (ADA) standard range. Therefore, these materials had acceptable clinical dimensional stability for approximately 168 h. In the current study, impressions were made from stainless steel dies following the ADA specification for impression materials. This provides a protocol that can be easily replicated by others and it is the same as making a clinical
Cosmetic dentistry is a specialized field that deals with improving the aesthetics of teeth and the human face. The teeth are an important part of human beauty. Even minor damage to the teeth, such as breakage or loss can drastically alter the overall appearance of the face. This is where cosmetic dentistry comes in to restore beauty. Cosmetic dentistry has become a highly specialized branch due to various advancements in surgical procedures and diagnostic techniques. Several new materials have also been discovered. These materials are very close to the natural enamel and bone from which teeth are made and are virtually indistinguishable. Cosmetic dentistry is an option in conditions such as teeth loss, gaps between teeth, cracked or chipped teeth, cavities and dental