Tartaric acid cements

Nicholson, J. W., Brookman, P. J., Lacy, O. M. Wilson, A. D. (1988b). Fourier transform infrared spectroscopic study of the role of tartaric acid in glass-ionomer cements. Journal of Dental Research, 67, 145CM. 

Table 5.11. Effect of +)-tartaric acid on glass polyalkenoate cement properties...

Table 5.12. Ejfect of the various tartaric acids on glass polyalkenoate cement properties Crisp, Lewis Wilson, 1979)...

The glass polyalkenoate cement system was not viable until Wilson and Crisp discovered the action of (+)-tartaric acid as a reaction-controlling additive (Wilson Crisp, 1975,1976,1980 Wilson, Crisp Ferner, 1976 Crisp Wilson, 1976 Crisp, Lewis Wilson, 1979). It may be regarded as an essential constituent and is invariably included in glass polyalkenoate cements as a reaction-controlling additive. 

Crisp, Merson Wilson (1980) found that the addition of metal fluorides to formulations had the effect of accelerating cement formation and increasing the strength of set cements the effect was enhanced by the presence of (-I-)-tartaric acid (Table 5.13). Strength of cements formed from an SiOj-AljOg-Cag (P04)2 glass, G-247, can be almost doubled by this technique. 

Cement formation with fluoride glasses - - -)-tartaric acid The presence of (+)-tartaric acid in a cement formulation exerts a profound effect on the cement-forming reaction. The nature of the underlying chemical reaction is changed and this is reflected in time-dependent changes in viscosity. 

Various attempts have been made to improve the glass polyalkenoate cement. We have already described (Section 5.9.5) the most important iimovation, the use of (-l-)-tartaric acid to improve setting characteristics (Wilson Crisp, 1976). Before its use was discovered, only one glass. 

Crisp, S., Lewis, B. G. Wilson, A. D. (1979). Characterization of glass-ionomer cements. 5. Effect of tartaric acid concentration in the liquid component. Journal of Dentistry, 7, 304-5. 

Copper(II) oxide and cobalt(II) hydroxide form cements with solutions of many multifunctional organic acids propanetricarboxylic acid, tartaric acid, malic acid, pyruvic acid, mellitic acid, gallic acid, tannic acid and phytic acid (Allen et al., 1984 Prosser et al., 1986). These have been used mainly in cement devices for the sustained release of copper and cobalt (Manston et al., 1985 Mansion Gleed, 1985). Little is known about... 

Oscillating rheometry continues to be useful in the study of AB cements, and has recently been used to give further insight into the role of (-1-)-tartaric acid in glass-ionomer cements (Hill Wilson, 1988). Further examples of its use are described in earlier chapters of this book. 

Ions released into the matrix as the cement sets may interact with the organic part of the matrix. Metal ions, such as Ca + and AP+, may be chelated by car-boxylate groups, either on the polymer or on the tartaric acid additive. These have been considered in reasonable detail in the literature [230]. What has received far less attention is the possibility that fluoride ions might interact with carboxylic acid groups, either to modify the setting reaction or to become relatively securely anchored within the set cement. This possibility was raised in a review published in 1998 [230], but has not been followed up subsequently. It is based on the well-established observation that fluoride ion will form extremely strong hydrogen bonds with carboxylic acids in aqueous solution. They are of the type ... 

Since the days of the first commercial glass-ionomer cement there has been an enormous amount of research aimed at improving the properties to the extent that modem materials are superior in every aspect to the original ASPA material. An early critical discovery was the role of tartaric acid in moderating the setting reaction [17]. This allowed glasses of improved translucency and lower fluoride content to be developed. 

S. Crisp, A.D. Wilson, Reactions in glass ionomer cements. V. Effect of incorporating tartaric acid in the cement liquid, J. Dent. Res. 55 (1976) 1023-1031. 

H.J. Prosser, C.P. Richards, A.D. Wilson, NMR spectroscopy of dental materials. II. The role of tartaric acid in glass-ionomer cements, J. Biomed. Mater. Res. 16 (1982) 431 45. 

In order to accelerate or retard the setting of cement, water-soluble admixtures may be used (see Section 5.3.1). Whilst many inorganic salts, such as calcium chloride, can act as accelerators, lead and zinc salts, borates and phosphates, as well as hydrocarbonic acids (e.g., citric acid or tartaric acid) and, most importantly, sugar derivatives such as raffinose or sucrose, will tend to retard the setting process. As the rate of setting can be determined by recording the heat evolved during hydration, a plot of (in Wkg ) versus 1/t will yield a close to linear relationship. 

Additives for calcium aluminate cement formulations have been described. Additives with primarily retarding and accelerating effects are tartaric acid, sodium carbonate, and lithium carbonate. Additives that primarily affect the consistency of the composition... 

The liquids used in glass-ionomer cements are acidic polyelectrolytes and are homo- or copolymers of acrylic acid in concentrated aqueous solutions (6,7). These polyacids are generally prepared by the aqueous polymerization of the unsaturated carboxylic acids using ammonium persulphate as initiator and isopropyl alcohol as the chain transfer agent. Tartaric acid is generally added to the liquids to sharpen the setting of their cement (8). Examples of the liquids used in ionomer cement formulations are given in Table 1. 

Early formulation of ionomer liquids - simple solutions of poly(acrylic acid) - only yielded workable cement pastes which set sharply when mixed with glasses of high fluorine content. This restricted the number of glass formulations which could be used in the system. Later it was found that other chelating and complex forming compounds had a similar effect (6), tartaric acid proved particularly effective and is now incorporated in all glass-ionomer cement formulations (6,8). 

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