Tin and Gold - Part 4
Fillings which are located upon the approximal surfaces of the teeth are much more difficult to finish than those in any other portion, and consequently require a higher order of skill, while for obvious reasons there is no class of fillings which demand greater care in their finishing, or which repay the operator a higher reward for faithful service rendered.
As a consequence of the difficulties encountered in finishing this class of fillings a great variety of instruments have been devised to overcome them. The oldest of these are the thin fiat files cut only upon one side and both edges.
Some of them are made with a spring temper, straight and curved ; others are tempered soft, and may be given any desired curve to suit the exigencies of the case in hand. These are shown in top image and are most useful in the anterior part of the mouth.
For trimming the cervical margins of the filling, the approximal trimmer shown top image is one of the most useful instruments devised for this purpose. This is file-cut upon one or both faces, and should generally be used with a drawing motion, the blades of the file being set with that object in view.
The sickle-shaped knife trimmers of Dr. Gordon "White, are also admirable instruments for trimming the cervical margins of fillings.
On account of the difficulties experienced in getting a clear view of the field of operation, it becomes necessary to examine the cervical margin by passing a fine probe or explorer over this portion of the filling, or, better still, floss-silk may be made to pass back and forth, from the cervix to the morsal border of the filling.
Especial attention should also be given to the morsal surface of those approximal fillings which involve this surface of the tooth, that perfect occlusion may be secured. If the crushing stress of the jaws is expended upon such a filling, it is bound, sooner or later, to be dislodged, either from the flow of the gold under stress, the disturbance of the anchorage, or from fracture of the walls of the cavity. Such surfaces should be so shaped that the filling will not be called upon to carry more of the load than the surrounding portions of the morsal surface of the crown or of the other teeth.
Fillings made of tin and tin and gold are finished in a similar manner.
This is an instructive summary of the qualifications and the duties of the present day Dental Assistant -- The Diplomat standing between the dentist and lost income. | read more |