Dr. B. Wood's plastic metallic filling : embraced in letters patent granted March 20, 1860, patent for the improvement allowed.

  • Wood, B. (Barnabas), 1819-1875.
Date:
[1864?]
Catalogue details

Licence: Public Domain Mark

Credit: Dr. B. Wood's plastic metallic filling : embraced in letters patent granted March 20, 1860, patent for the improvement allowed. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    with facility and accurately secured. It mould.- close!) Bo the wads of the cavity without recession or shrinkage, forming a perfect plug, solid throughout, that effectually excludes air and moisture. The proportions are adjusted so tha shall expand very slightly rather than contract, upon solidification, sufficient to make a close fit, but not enough to injure the frailest shell of a tooth. It can 1m; built out from broken and defective teeth, so as to restore their original form and usefulness. In this way entire crowns have been restored fen- the support of clasps as well as for use in mastication. In such cases, should the cusps or points become abraded by continued wear, as any material may, they can be- readily built out again, whereas when gold foil or sponge gold chips out or wears off under like circumstances, it is difficult, if not impractical of renewal. The metal is of close, compact texture, like solid tin or gold, and cannot absorb the buccal secretions, as do the earthy and metallic pastes, and also gold and tin foils when not well condensed; it therefore does not, like these become tainted and offensive, but remains absolutely free from any interstitial impurity. At a temperature but little higher than that of ordinary hot drinks, and yet not low enough to be affected by them, it is rendered soft and plastic, suitable for application, while at a heat liable to do harm, it becomes too fluid to work; by this it is self-guaged and within control,—being its own thermoscope. Operations with it are generally more expeditiously performed, and attended with less dis- comfort than with gold; in cases of highly sensitive dentine the pain is fa| less than that produced by removing the decay and but momentary • but in ordinary cases there is no pain at all experienced in introducing it. As it solidifies upon introduction, it is of immediate service for mastication, and not liable like amal- gams and other cements, to wear off or to crumble out. Itcontainsno mercury, nor is it allied in composition or qualities to amalgams,* and it is free from their objections. Neither can it blacken the tooth-bone as these preparations are necessarily liable to do. The amalgam employed for stop- ping teeth, (commonly called cement. or silver cement,) is composed of an alloy of silver with one or two parts tin, or one-tenth part copper (coin,) generally both, for pure silver does not harden well, and therefore is not used, which alloy is reduced to fillings, and mixed up with mercury (quicksilver,) into a paste for introduction into the tooth cavities, where it hardens after a while. But mercury is a fluid capable of permeating any tissue; it is also volatile and slowly vaporizes at any temperature; and as it has but a feeble affinity for the other metals in the compound, the particles of which it serves to agglutinate, it gradually elminates itself in part, permeating the tubular structure of the tooth which it blackens; for its particles finely comminuted are dark, and this is intensified if oxidated or com- bined with sulphur. This also leaves the plug porous to imbibe impurities. The constituents of the Plastic Metallic Filling are. on the contrary, all perma- nently solid. The metal can undergo no change or loss of substance, except what might occur from the surface. It therefore does not. nor indeed can it * The word Amalgam denitts. a combination of Mercury with another metal.