Conservative Class II Foils
Presented at the Annual Meeting of the American Academy of Gold Foil Operators in San Francisco, California on November 6, 1964.
Dr. Smith is in
private practice in Seattle, Washington and is on the Operative
Dentistry staff at the University of Washington. He is Chairman of the Operative
Section of the American Dental Association and Director of the John Kuratli
Crown and Bridge Seminar. He has been a member of the University Ferrier
Gold Foil Club for 17 years. In his spare time, Dr. Smith enjoys sailboat racing.
Reprinted from the Journal, American Academy of Gold
Foil Operators, Vol. 10, No. 1, April 1967
THE CLASS II GOLD FOIL. RESTORATION can he one of the most beautiful, delicate and functional restorations placed in a human tooth. Its replacement of diseased structure may be so fine as to withstand the damaging effects of decades of oral service. Usually it requires a little above average skill, but with training, restorations can be made within a reasonable length of time and with a minimum of discomfort for the patient. Many sleep while the operation is being done.
To use the term "Conservative" Class II foil is almost like repeating oneself. For this restoration is conservative above all other Class II types. However, there are some specific locations where the operation may he more easily accomplished and there are some conditions under which one may work more rapidly and easily. In addition to this, there are factors which make a Class II foil the operation of choice over an inlay from purely the standpoint of conserving tooth tissue for the patient.
As Ferrier1 has said, “Consider only the tooth as an organ not capable of regenerative processes, such as bone, muscle, and mucous membrane, that once any part of it is lost, it can never he restored in kind; and that any restoration in any material falls far short of the original."
Naturally, logic tells us that the first thing we can do is to save and conserve all possible dental tissue for the patient. And in considering incipient decay, gold foil is far superior than any inlay, for we can adapt the material to the needs of the case and not cut the tooth to suit a technique, which depends ultimately upon the withdrawal of a wax pattern from either a tooth or a die to establish the completed restoration.
So as prime indications we find (1) crowded or rotated teeth where an inlay would waste structure (Figs. I & 2); (2) bell crowned teeth for the same reason; (3) mesials of mandibular first bicuspids where no occlusal extension is required; and (4) generally speaking, mesial Class II cavities, as they are much easier for the average dentist who may not be familiar with the work.
A few general points are well to consider. On any mesial surface, a Class II foil has greater esthetic benefits. An inlay nearly always will show some gold. Often the operator has cut off the so-called "ears" of the bicuspid in preparing the inlay cavity, and amalgam used in these areas almost always shows through as a slight darkening. It is much easier to learn to condense the gold well on the mesial preparations. The angle of force is more natural and requires less use of highly offset bayonet condensers. In addition, when the work is done, it is more convenient to find any possible marginal or gingival angle deficiencies and to repair them with greater facility.
Distal Class II preparations, though slower and more awkward to fill, have one advantage in that the finishing strips and disks tend to lay in such a manner as to expedite finishing procedures. The use of the pneumatic or electromatic condensers render many of these areas highly accessible.
Condensation or compaction is the heart of all foil work — especially so in the Class II. The proximal gold should be layered and wedged toward each proximal wall. The vertical condensation should step out slightly beyond the cavosurface angle to give good wall adaptation, and the contact point should be well formed and condensed against the adjacent tooth using cohesive foil and not soft foil. A matrix has no place in this technique as lateral condensation later
uses the excess gold for density and good coverage in finishing proximal and gingival margins. Minimum proximal extension often avoids great time waste. Over extension allows non-cohesive cylinders to slip out and makes it easier to add excessive amounts of foil on the lingual. Time is not only wasted in adding the excess gold, but often to a much greater extent in finishing it off.
Perhaps it is well to mention a few of the most common causes of difficulties or failures. One of the more frequent is inadequate condensation in the proximal gingival angles. This must be avoided in the placement and condensation of the three non-cohesive cylinders. These are usually two 1/8 cylinders and one 1/4 cylinder of No. 4 gold. They are swept powerfully into position with the No. 13, No. 14 parallelogram condensers in both a lateral and gingival direction, then condensed vertically with the large square bayonet condenser of the Ferrier study club set. Their final height when condensed should be about 2/3rds of the height of the axial wall. This allows room for the following cohesive foil to aid in the retention of the proximal and to form the contact point.
Another common error is the use of an incorrect angle of force along the buccal-occlusal walls of the preparations. To correct this tendency, a bayonet condenser or a right angle head in the pneumatic or electromatic condenser must he used. This is also frequently necessary on the mesial walls of distal cavities.
Proper layering of the gold bucco-lingually as described by Black2 can be of great assistance in these situations. Yet from a biological standpoint, care should be exercised not to produce excessive wedging effects and pressures, as these can create hypersensitivity or even crack teeth.
These biological considerations are usually the normal ones we face in most operative procedures. There should he adequate pulpal protection from thermal shock during preparation procedures as well as suitable use of bases or medicaments to prevent post-operative complications. This may include prednisolone, calcium hydroxide and zinc oxide bases, or simply gum copal varnish. However, if sizable bases are necessary, the condensing pressures on the base should be considered. Sometimes a stronger base of zinc phosphate cement with alloy filings added is indicated. But the larger the cavity area the less the case is indicated for a foil restoration and the more an inlay or alternate procedure should be considered.
The separator can be a vicious instrument if care is not employed in its use. It should first be selected carefully to fit the case so that torsion effects are not incorporated. The jaws should be deli-
cate and not impinge on the tissue. The screws should be free with a little "play" to avoid forceful wrench action and give more accurate control. Finally, the separator should he well stabilized with compound to avoid tissue damage and distribute pressures over four or five teeth.
C A V I T Y P R E P A R A T I O N
With high speed a preparation can he cut very rapidly and efficiently, but the operator must have a clear picture of the preparation in mind to avoid overcutting or loss of detail. Fine cavity detail is of great importance in ensuring convenience of insertion of the gold and durability of the finished restoration.
The occlusal (Fig. 3) should be cut with a 700 series but which has been broken and squared off to about 4 of its normal length. This automatically will set the proper depth and inclination of the walls. The walls must be slightly divergent in the isthmus area and at the occlusal wall distal to the proximal. This strengthens the marginal ridge. The only occlusal retention used should be gained at the expense of the buccal and lingual walls where they reach the distal. Proximal extension should be minimal to aid in supporting the
non-cohesive foil and aids in a better esthetics. No bevels should be on any walls where non-cohesive foil is employed and only the fine finish of sharp cutting instruments is necessary to plane all walls to proper outline and completion.
One of the greatest aids to finishing procedures is a set routine. It is more than a convenience, it is a necessity. This is the one area where many men repeat and duplicate actions, wasting time, until they eventually end up with a completed operation. The use of burs, files, gold knives and the Scarl swagger* should preceed the use of graded disks. An interesting miniature burnisher is of great convenience in finishing occlusals. The small instrument has short extensions which permit the operator to exert greater burnishing force with less tendency for the instrument to twist within his grasp. Also, the small burnishing surfaces are more suited to our present delicate cavity extensions. (Fig. 4)
Finishing burs may he moistened with water to prevent "leading." They usually consist of two types: one, a squared off 700 series bur, is very fast and convenient in setting the inclined planes and central groove; the other — a round bur — may he right or left cutting, and is very helpful in trimming gold to margin, especially in the extensions. Finally, a dull number 1/2 round bur is excellent to accentuate and define previously established grooves.
The separator should be known by number; usually the Ferrier No. 4 is indicated for Class II foils. Occasionally, the No. 3 will be better on the angle of the arch for mesial restorations in first bicuspids. This depends upon the narrowness of the arch and the conformity of the teeth.
After all gross finishing is done, i.e., the gingival and all occlusal anatomy with the exception of the occlusal embrasure, the separator should be placed momentarily and a Gordon White saw passed through the contact area. A lightning strip and subsequent finer extra long finishing strips (Moyco) should he used with copious amounts of air. This will leave a beautifully finished and polished interproximal surface.
The strips should he manipulated with care and relieved at either buccal or lingual surface to maintain proper contact point relation-ship and correct embrasures at this time. The occlusal embrasure should receive special consideration. A sharp gold knife or small cleoid swept across the marginal ridge while the separator is in place will set up the proper angulation for the embrasure and the escape gate. It is often convenient to mount a large but extra fine cuttle finish disk in the straight screwhead (small-size) mandrel. This will by-pass the separator frame and nicely round out and highly finish the embrasure.
A step by step logical finishing routine will reward the operator with consistently excellent results with a happy, rested patient.
An ideal Class II from the standpoint of ease of operation is the mesial of the lower first bicuspid. (Fig. 5) Because it occludes with the upper cuspid only, there is no stress on the occlusal surface and no occlusal extension is necessary. Both buccal and lingual proximal walls make acute angles with the gingival due to the shape of the adjacent mandibular cuspid. The interior has accentuated axial line angles to help retention. An excellent instrument for this delicate feature is the special gingival margin trimmer No. 28 and No. 29*.* These were designed by C. T. Fleetwood and arc also of great convenience in lingual approach Class III foils. (Fig. 6)
Usually only three 1/16th non-cohesive gold cylinders arc placed at the gingival. The cohesive gold placement is delicate and wedging should be carefully accomplished to ensure good wall adaptation.
—Suter Dental Instrument Co., Chico, California
Finishing procedures are minimal and the operator can easily see and check his work.
The result is a delicate, beautiful and inconspicuous Class II restoration.
To cut across the large and solid transverse ridge would be a waste, both of time and tooth structure, for this tooth is much like an overgrown cuspid. A central groove is almost never present. If a groove is present, it is nearly always in the distal portion of the occlusal. (Fig. 7) In addition, if an occlusal extension were made, the great size of the buccal cusp would tend to augment thermal shock because of gold being closer to the extension of the pulp.
One of the first questions asked by men tempted to try Class II foil work is, "How much time should this operation take?" Naturally, the correct answer is, "Enough time to do the case at hand properly." However, to quote averages which may be helpful, two to two and a half hours should be allowed in the beginning. Later, an hour and a half to two hours should he adequate. Ideal cases have been done in an hour or even 45 minutes by highly skilled men, and the most remarkable time of 40 minutes, including anesthetic administration, has been witnessed.
To return to normal considerations however, it's safe to say that the time consumed to create a beautiful Class II foil is nearly always less than the time and effort required to produce and cement a Class II inlay. The operator should not think in terms of speed,
but in terms of excellence, efficiency and service.
Lastly, let us consider contra-indications. It is proper here to quote the Latin legal phrase, res ipsa loquitur, the thing speaks for itself. For professional experience, training and judgment are almost perfect guides to the average man. A tooth without proper gingival support would certainly not be a likely candidate to receive condenser blows or even give good gold condensation. Large cavities imposing undue stress on the patient or the tooth are questionable to use. Devital teeth, or those with impaired circulatory protection, should he avoided if possible. Then, once in a great while, the unusual patient will appear who is psychologically unsuited to stand the malleting or condensing blows. Fortunately, the usual patient, on the other hand, seems to actually enjoy his brief period of relaxation while the foil is placed.
In conclusion, it is hoped that some ideas and aids toward operational procedures will have been found here. If so, the author may have partially repaid his debt for some of the help and assistance gained from predecessors.
Ferrier, W. I.: Gold Foil Operations, University of Washington Press, Seattle, 1959.
Black, G. V.: Operative Dentistry, Volume II, Medico Dental Publishing Co., Chicago, Illinois,1908, Pgs. 271-2.