Repairing Defective Gold Fillings
Gold fillings which are defective from imperfect adaptation to an enamel margin, from recurrence of caries, or from fracture, are often susceptible to repair.
These cases many times present problems which are by no means easy to solve. In the consideration of the question, each case offers a peculiar condition which makes it necessary to treat it upon its individual needs. This consideration must take into account the nature of the defect, its location and accessibility, the condition of the remaining filling, and the material best suited for repairing the defective condition.
Defects which are the result of imperfect adaptation to an enamel margin are usually discovered during the finishing of the filling, and if the rubber dam has not been removed, the defect may be readily repaired with cohesive gold. Sometimes it may be necessary to cut away the filling at the defective point, forming a cavity in it of retentive shape. If the filling has been in contact with the saliva, the rubber dam must be adjusted, and the filling cleaned by bathing it with alcohol, ether, or chloroform, after which the defective point may be prepared as above, and filled with cohesive foil or crystal gold.
Defects resulting from recurrence of caries are most often found at the cervical border of approximal fillings. Thorough separation of the teeth ' is necessary to successfully repair such defects.
Defects of this character can often be repaired most efficiently by using non.cohesive foil cut in narrow ribbons, and packed into the cavity fold after fold, allowing the loops to project beyond the margins of the cavity, and when the cavity is full, thoroughly condensing the projecting loops and finishing the filling with emery strips, etc., in the usual manner.
If cohesive gold is used, a retentive shape must be given to the cavity, and a groove or pit provided for holding in place the first piece of gold.
The bicuspids and molars offer the most difficult cases to repair, by reason of their inaccessibility. Gold is the best material with which to make such repairs, provided the cavity can be made accessible ; but sometimes it is not possible to accomplish this except by removing the entire filling, and this, when the filling is large and otherwise good, seems unfair to the patient, if there is a reasonable assurance of making a successful repair with, one of the plastics. Gutta-percha is often successfully used in these places, but occasionally it will be found to undergo decomposition, and is therefore not as reliable as gold. The oxyphosphate cements are contraindicated on account of their tendency to dissolve and wash out after a brief period. Amalgam is more often used than any other plastic for this purpose, on account of the readiness with which it can be introduced into cavities that are entirely inaccessible to gold, and the greater assurance of making a good repair. It has the disadvantage, however, of becoming very black after a few weeks of contact with the gold, but this does not lessen its value as a tooth preserver. On account of the black discoloration which always follows this use of amalgam, it should not be used in the anterior teeth.
After the amalgam has become hard, it should be finished as carefully as possible, by removing all overlapping edges and polishing in the usual way.
Defects caused from fracture of portions of the cavity walls is a not infrequent accident, and one which may be successfully repaired, provided the filling has been firmly anchored in other portions of the cavity and the tooth is sufficiently strong to warrant the necessary retentive shaping of the cavity to receive the repair.
The incisors are prone to such accidents; the most common being the loss of the mesio-morsal or disto-morsal angle when large approximal fillings are situated well towards the morsal edge. Eepairs of this kind are difficult to make, but they may be successfully accomplished by taking advantage of the favorable conditions that are presented. Each case must be carefully studied and treated according to the indications. No rule can be laid down for such cases. The operator must depend upon his knowledge of mechanics and his ingenuity to suggest a way to overcome the difficulties of each case as it is presented.
Anchorage may sometimes be secured by drilling a retaining-pit in the ' filling at one angle, and another in the sound dentin at a different angle, or shallow retaining grooves or channels may be cut in the labial and lin-. gual walls of the cavity and re-enforced by a pit drilled into the filling. Crystal gold will be found most serviceable in this class of operations.
Accidents of this character sometimes occur in the bicuspids and the molars, most often in the bicuspids, especially when these teeth have been filled upon their mesial and distal surfaces, with the fillings uniting upon the morsal surface. The buccal or the lingual wall may be broken away by stress so applied between the cusps as to split off the weaker of these walls.
The prospect of successfully repairing these cases will depend upon the security of the anchorage of the approximal fillings, and the opportunity for obtaining good anchorage at the cervical border and laterally in the approximal fillings. When the buccal wall is lost it would be better practice, for cosmetic reasons, to amputate the balance of the crown and place an artificial crown upon the root.
If the lingual wall is lost, the objection to restoring it with gold is not so strong. Crystal gold gives the most satisfactory results/in all cases of this character.
Occasionally amalgam can be used for restoring the lingual cusps of a second bicuspid, but the discoloration which eventually follows makes this .substance objectionable.
Fractures of a similar character occurring in the molars are, as a rule, less difficult to repair, as they will usually admit of the proper retentive shaping without the same degree of danger to the pulp as accompanies the operation in the bicuspids. In those cases of fracture which extend beneath the gum, the difficulties are increased by the hemorrhage likely to attend the operation, and the difficulty experienced in retaining the rubber dam in a position beyond the fracture. Mack's screws can sometimes be set in such position as to offer strong anchorage and not encroach upon the pulp. Under such circumstances they become a valuable adjunct to the other means of anchorage. Cohesive gold only can be used for such repairs, and the form usually indicated is Watts's crystal gold.
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