Dental products, requirements

Many liquid detergent products contain components that serve as product viscosity modifiers, added to achieve the desired consistency of the commercial product. Cellulosic polymers, for instance, are an excellent example of such an additive and various polysaccharides are capable of gelation under specific thermal conditions. In such cases, heat transfer during manufacture may be required to complete hydration and effect the necessary conformational change in the select polymer system [85], in the appropriate aqueous environment. Products requiring controlled heat transfer processes may include various dental creams, shampoos, built liquid detergents, and hard surface cleaners. 

Measurement of C requires more sophisticated and expensive rheometers and more involved experimental procedures. It must be remembered that experiments have to he carried out below the critical strain value (see Sec II), or in [he region of linear viscoelastic behavior. This region is determined by measuring the complex modulus G as a function of the applied strain at a constant oscillation frequency (usually 1 Hz). Up to 7, G does not vary with the strain above Yr, G tends to drop. The evaluation of oscillatory parameters is more often restricted to product formulation studies and research. However, a controlled-fall penetrometer may be used to compare the degree of elasticity between different samples. Creep compliance and creep relaxation experiments may be obtained by means of this type of device. In fact, a penetrometer may be the only way to assess viscoeIa.sticity when the sample does not adhere to solid surfaces, or adheres too well, or cures to become a solid or semisolid. This is the case of many dental products such as fillings, impression putties, sealants, and cements. 

In 1996, the European Union (EU) required all manufacturers to have a quality system compliant with ISO 9000 and demonstrate that the products met the requirements of the Medical Device Directive (for safety) in order to gain the right to carry the CE mark. All dental products sold within the EU are required to have the CE mark and to comply with the appropriate ISO standard if one existed. The EU adopted ISO 13485, a quality system for the medical and dental industries superseding ISO 9000 the EDA accepted the use of ISO 13485. 

A primary responsibility of the Food and Drug Administration (FDA) is the enforcement of the Federal Food, Dmg, and Cosmetic Act of 1938 and its various amendments, eg. May, 1976, in which dental materials, instmments, and equipment are included. Premarketing clearance requirements apply for estabhshing the safety and effectiveness of new products. There is a close Haison between the FDA and the ADA standards and certification programs. 

Eluoride added to a compatible dentifrice base at a level of 1000 ppm has been clinically proven to reduce the incidence of dental caries by about 25% on average, even in areas where the water supply is fluoridated (4). Elevation to 1500 ppm increases the protection. Sources of fluoride approved for use in dentifrices are sodium fluoride [7681-49-4] (0.22%), sodium monofluorophosphate (0.76%), and stannous fluoride [7783-47-3] (0.41%). The Eood and Dmg Administration regulates fluoridated dentifrices as dmgs and has estabUshed parameters for safe and effective products. CompatibiUty of the fluoride with the abrasive is an important requirement. 

Therapeutic levels immediately after infusion, irrespective of which product is used, require factor VIII levels between 5 and 20 % for hae-marthrosis and muscle bleeds. However, haematoma in dangerous areas, such as extensive dental extractions, should have levels between 20 and 40 %. For major surgery and serious accidents these need to be between 100 and 150 % levels should not drop below 50 % at any point in the day and should continue until wound healing is complete in major surgery this may be 7 or 10 days. 

The answer is e. (Murray, pp 627-661. Sciiver, pp 3897-3964. Sack, pp 121-138. Wilson, pp 287-320.) Ascorbic acid (vitamin C) is found in fresh fruits and vegetables. Deficiency of ascorbic acid produces scurvy, the sailor s disease. Ascorbic acid is necessary for the hydroxylation of proline to hydroxyproline in collagen, a process required in the formation and maintenance of connective tissue. The failure of mesenchymal cells to form collagen causes the skeletal, dental, and connective tissue deterioration seen in scurvy. Thiamine, niacin, cobalamin, and pantothenic acid can all be obtained from fish or meat products. The nomenclature of vitamins began by classifying fat-soluble vitamins as A (followed by subsequent letters of the alphabet such as D, E, and K) and water-soluble vitamins as B. Components of the B vitamin fraction were then given subscripts, e.g., thiamine (Bi), riboflavin (B2), niacin [nicotinic acid (B3)], panthothenic acid (B5), pyridoxine (Bg), and cobalamin (B ). The water-soluble vitamins C, biotin, and folic acid do not follow the B nomenclature. 

The most common dental polymers, used for prosthetic purposes and restorative dentistry (filling material), are polymethacrylates.1514 The polymerization process performed directly in the dental cavity has to meet strict demands the reaction must be fast at a temperature below 50 °C and it must avoid the formation of a toxic product. These requirements can be fulfilled by UV curing. For example, a mixture of camphorquinone (586), a chromophore (photoinitiator) with an absorption maximum at 468 nm and an amine 587 as a co-initiator (see also Scheme 6.100), initiates a radical polymerization reaction of the acrylate monomer 588 upon photolysis using a conventional blue lamp or laser (Scheme 6.285). 

The application of polymeric materials in medicine is a fairly specialized area with a wide range of specific applications and requirements. Although the total volume of polymers used in this application may be small compared to the annual production of polyethylene, for example, the total amount of money spent annually on prosthetic and biomedical devices exceeds 16 billion in the United States alone. These applications include over a million dentures, nearly a half billion dental fillings, about six million contact lenses, over a million replacement joints (hip, knee, finger, etc.), about a half million plastic surgery operations (breast prosthesis, facial reconstruction, etc.), over 25,000 heart valves, and 60,000 pacemaker implantations. In addition, over AO,000 patients are on hemodialysis units (artificial kidney) on a regular basis, and over 90,000 coronary bypass operations (often using synthetic polymers) are performed each year (]J. 

Synthetic pol)mieric materials have been widely used in medical disposable supply, prosthetic materials, dental materials, implants, dressings, extracorporeal devices, encapsulants, polymeric drug delivery systems, tissue engineered products, and orthodoses as that of metal and ceramics substituents [Lee, 1989]. The main advantages of the polymeric biomaterials compared to metal or ceramic materials are ease of manufacturability to produce various shapes (latex, film, sheet, fibers, etc.), ease of secondary processability, reasonable cost, and availability with desired mechanical and physical properties. The required properties of polymeric biomaterials are similar to other biomaterials, that is, biocompatibility, sterilizability, adequate mechanical and physical properties, and manufacturability as given in Table 40.1. 

Xylitol, a sugar alcohol, has potential use as a natural food sweetener, a dental caries reducer and a sugar substitute for diabetics. It is produced by chemical reduction in alkaline conditions of the xylose derived mainly from wood hydrolyzate (169). The recovery of xylitol from the xylan fraction is about 50-60% or 8-15% of the raw material employed. Drawbacks of the chemical process are the requirements of high pressure (up to 50 atm) and tenq>erature (80-140°C), use of an expensive catalyst (Raney-Nickel) and use of extensive separation and purification steps to remove the by-products that are mainly derived from the hemicellulose hydrolyzate (770). The bulk of xylitol produced is consumed in various food products such as chewing gum, candy, soft drinks and ice cream. It gives a pleasant cool and fresh sensation due to its high negative heat of solution. 

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