Simple Approximal Cavities
This class of cavities are those which are found upon the approximal surfaces of all the teeth, but which' do not involve any other surface, and are bounded by a continuous and unbroken wall.
Cavities of this class occurring upon the approximal surfaces of the incisors and cuspids generally require preliminary^ treatment by temporary separation, either by tape and wedges, or the more rapid method with the Perry or other screw separator. If the cavity is small and well within the labio- and linguo-mesial or distal angles, the case presents no difficulties other than those growing out of its degree of inaccessibility. Such cavities may be two-thirds filled with non-cohesive foil, cut in narrow ribbons, and the balance with cohesive foil. Curved pluggers are necessary in filling these cavities, on account of the proximity of the adjoining teeth."
In cavities which involve a considerable portion of the approximal surface, retention is secured at the cervical border by a groove at the base of the cavity, combined with a retaining-pit at the extremities, and by a shallow undercut at the morsal border. Grooving the labial or lingual walls for the purpose of retention is to be deprecated, as it tends to weaken them, and increases the liability to fracture arid dislodgement of the filling.
The dentist who possesses the spirit of the true artist will at all times endeavor to conceal the gold as much as possible when he is called upon to place it in the anterior teeth. Consequently he will, whenever possible, conserve the labial wall of these teeth. The filling should be started in one of the retaining-pits at the extremity of the groove made at the cervical border, then the pit in the opposite extremity should, be filled, and both united by attaching a ribbon of gold from one to the other, and malleting it into the retaining groove. This gives a firm foundation upon which to build the filling and secures thorough adaptation of the gold to the cervical wall. The balance of the filling is then completed after the manner already described in filling simple cavities.
Cohesive gold, either foil or crystal gold, is best adapted for fillings of this character.
Simple approximal cavities in the mesial or distal surfaces of the bicuspids and molars offer considerably more difficulty in filling than similar cavities in the anterior teeth, by reason of their less accessible position. Temporary separation is always necessary in those cases presenting a normal approximation of the teeth. When the cavities are large it often becomes necessary, in order to gain a clear view of all parts of the cavity, to convert a simple into a compound one; or this procedure may be necessary on account of the extension of the disease in directions which undermine the enamel, making it too frail to bear the stress of mastication.
Simple cavities in these locations may be filled after the manner described for filling similar cavities in the anterior teeth, with the exception that by reason of their greater degree of inaccessibility hand-pressure becomes necessary in packing the gold for the greater part of the operation. Non-cohesive foil can be used* to advantage in this class of fillings if used in narrow ribbons, or loosely rolled cylinders or pellets, and the surface finished with cohesive foil. Some operators prefer cohesive gold throughout the operation. In such case the filling is started in small undercuts or pits made at the cervical border.
The mallet is sometimes used for condensing the surface, but it is less applicable to the distal surfaces than to the mesial.
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