Screw-type attachments for fixed partial dentures

Screw-type A. Merlin Delray

attachments

Wuebbenhorst,

for fixed

partial

dentures

D.D.S.

Beach, Fla.

Ah e sp l’t’ m mg together of teeth involved with advanced periodontal disease has been advocated for many years .I Splinting along with the application of a good working knowledge of occlusal stresses2-4 allows these teeth to be stabilized and maintained for the longest period of time. In the technique described in this article, an understructure and superstructure concept is employed. The understructure consists of telescopic crowns with attached segments that receive screws which lock the superstructure in place. The superstructure completes the form of the clinical crowns of the teeth and pontics. The objectives of this technique are to preserve natural teeth that have a poor prognosis or lack adequate parallelism for other types of fixed restorations.

ADVANTAGES

AND DISADVANTAGES OF THIS TECHNIQUE

Some of the problems that this technique solves are: (1) nonparallel teeth can be utilized for fixed partial dentures, (2) teeth involved with advanced periodontal disease can be used in fixed partial denture and rehabilitation work, (3) involved teeth can be removed and the superstructure can be altered to replace them, (4) resin flanges can be added to pontics to replace missing tissues, (5) the superstructure may be removed simply whenever desirable for periodontal supervision, (6) the superstructure can be replaced accurately because no cement is required to hold it in place, and (7) a program for future dental treatment is incorporated in the original treatment plan. The disadvantages of this technique are: (1) the teeth must be reduced more than for other types of abutment preparations and (2) the initial financial investment is greater than for routine fixed prosthodontics.

SPECIAL INSTRUMENTATION A minimum of special equipment is required for this technique. A C. A. Handpiece screwdriver* (Fig. 1) and a Tele-Seal/Pontic-Seal kit* are required (Fig. 2). “J. F. Jelenko

& Company,

Inc., New Rochelle,

N. Y.

275

276

J. Pros. Dent.

Wuebbenhorst

Scptrmbr,r.

1971:

Fig. scre

Fig. , 2. The Tele-Seal/Pontic-Seal the components of the attachment.

kit contains

the necessary instrumentation

to properly

Iocate

PREPARING THE TEETH All abutment teeth are prepared with a circumferential shoulder to make space for the telescopic crowns and to permit the superstructure to be developed with normal crown forms. Chamfers or bevels are made after the shoulder has been prepared. If a retention screw is to be placed between adjacent teeth, the adjacent surfaces of the teeth must be adequately reduced (Fig. 3) .

Screw-type

Fig. 3. Adjacent attachment.

surfaces

Fig. 4. A thin plastic the dies of the prepared

DESIGN

of teeth are reduced

coping with teeth.

wax gingival

adequately

margin

attachments

to provide

for dentures

277

space for the Tel&Seal

and added segments is developed

on

OF THE UNDERSTRUCTURE

A thin plastic coping is formed over the dies of the prepared teeth. Wax is added at the gingival margin to form the segments attached to the copings (Fig. 4). A cantilevered segment is constructed for the edentulous spaces (Fig. 5). The attached segments should be located as far buccally or labially as possible so that proper lingual anatomic form may be obtained on the superstructure (Fig. 6), DESIGN

OF THE SUPERSTRUCTURE

A thin plastic placed in position.

coping is formed over the cast coping and a Tele-Seal tube is The end of the threaded portion of the Tele-Seal tube must be

278

J. Pros. Dent. September, 1970

Wuebbenhorst

Fig. 5. A cantilevered main .tained.

segment

is located

in an edentulous

Fig ,. 6. The attached segments should be placed as far buccally Pm Iper lingual anatomy.

space. Proper

or labially

embrasure

form

is

as possible to insure

Volume 24 Number 3

Screw-type

Fig. 7. The Tele-Seal material.

tube extends

from

the wax pattern.

attachments

for dentures

279

The tube is held by the investing

firmly placed at right angles to the surface of the attached segment and fit flush against it. The waxing of the superstructure is completed, making certain that no wax enters the tubes. The tube is permitted to extend from the lingual surface of the pattern so it will be held by the refractory investment. The pattern and tube are invested so the investment material completely fills the tube (Fig. 7). The pattern is cast and finished in the normal manner. However, the threaded section of the tube should not be sandblasted. Jet-Bright* can be used as it will not damage the threaded portion of the tube. Hydrofluoric acid is used to remove all excess investment from the tube, as probes could be damaging. THREADING

THE COPING

The drill is clamped in its chuck so that it extends through the drill jig 1.5 mm. (Fig. 8). Then the jig is removed and inserted into the Tele-Seal tube until the jig contacts the shoulder of the coping (Fig. 9). With the use of either a lathe or handpiece, the drill is replaced in the jig and drilling continued at slow speed until the chuck contacts the jig. This procedure automatically insures the proper depth hole in the coping or attached segment for the “seat finder point” on the screw (Fig. 10). While drilling, the drill must be oiled and the chips should be cleared by occasionally withdrawing the drill to prevent breakage. The copings and fixed *J. F. Jelenko

& Company,

Inc., New Rochelle,

N. Y.

280

Wuebbenhorst

Fig. 9. The drill

is in the T&-Seal

Fig.

10. A cross section

Fig.

11. The

tube ready to drill

of the Tele-Seal

brass technique

a hole in the attached

tubr shows a screw with

screws verify

alignment

screws are also used during processing with acryfic resin.

following

“seat finder

the drilling

segment.

point”

at A.

operation.

The

Volume 24 Number 3

Screw-type attachments for dentures

281

partial denture must be securely held in exact alignment during the drilling operation to assure accuracy of the final alignment. screws are inserted in each TeleThe drill jig is removed and brass “technique” Seal tube to check the drilling operation for alignment (Fig. 11) . Then the stainless steel screws are inserted and the hollow portion of the tube is cut back to be consistent with proper lingual anatomic form and finish.

Fig. 12. The recess in the casting will receive the Pontic-Seal

Fig. 13. Duralay for soldering.

is holding

the female

section

assembly.

of the Pontic-Seal

assembly prior

to investing

282

J. Pros. Dent. 1970

Wuebbenhorst

September,

VENEERlNG PROCESS When acrylic resin veneers arc: used, the brass %:chnique” screws are inserted in the Tele-Seal tubes to prevent plaster or acrylic resin from getting into the tubes during processing (Fig. 11) , Whc~n using porcelain, the brass technique screws arf: removed before firing the porcrlain. Estrrmc care should be taken so that porcelain does not enter the tubes.

Fig. 14. The superstructure

is complete

following

soldering

and polishing

sembly.

Fig. 15. A paralleling

instrument

is used when nonparallel

teeth are involved.

of Puntic-Seal

as-

Volume 24 Number 3

TECHNICAL

Screw-type attachments for dentures DESIGN

OF THE PONTIC

283

SEAL

When no understucture is employed, the abutment is prepared without a shoulder on the lingual aspect of the tooth. However, the shoulder is extended interproximally to make space for the Pontic-Seal assembly. The crowns are waxed to receive the Pontic-Seal assembly. The female part is used to form a recess in the wax pattern and is lubricated well so that it can be easily removed from the pattern. The female part is located as far buccally or labially as possible to allow maximum length of the tube and to permit the holding screw to be recessed. The casting is completed with a recess that receives the Pontic-Seal assembly (Fig. 12). Duralay” is used to retain the female part (Fig. 13)) and this section is invested so that the female part may be soldered to the crown (Fig. 14). A paralleling instrument is used when nonparallel teeth are involved (Fig. 15). The holes are drilled into the male section in a similar manner as into the attachments of the copings. INSERTION

OF UNDERSTRUCTURE

AND

SUPERSTRUCTURE

The understructure is permanently cemented to the teeth. The superstructure is attached by placing the screws. The dentist locates the screwdriver in the groove of *Reliance

Dental

Mfg. Company,

Chicago,

Fig. 16. The screws are placed through

111.

the superstructure

and into the understructure.

284

J. Pros. Dent. September, 1970

Wuebbenhorst

the screw head while the dental assistant slowly turns the knurled knob or the I lulley end of the handpiece (Fig. 16). When the screw is tightly seated, a thin coating of lubricant is placed over the screw head, and a material that can be easily drilled out is placed into the v,acant spatce in the tube. A quick-cure acrylic resin or a zinc oxyphosphate cement m ay be Ll.

Fig. 17. An advanced

periodontal

Fig. 18. The cuspid and bicuspid

condition

are replaced

involves

the cuspid and first bicuspid.

with the tissue defect restored.

Volume 24 Number 3

Screw-type

attachments

for

dentures

285

A temporary cement may be used for the superstructure. If this procedure is followed, the copings should be adequately lubricated prior to placing the superstructure. The excess temporary cement must not be allowed to creep into the tubes before the screws are placed. SUMMARY

AND

CONCLUSIONS

A restorative procedure that utilizes a superstructure that can be easily removed has been described. The superstructure is attached accurately and securely to the undersfructure by placement of selectively located screws. This technique has been used satisfactorily for many patients (Figs. 17 to 20). Some of the benefits of this procedure are: maximum retention and stability of remaining teeth with poor prognosis, the ease with which fixed partial dentures can

Fig. 19. The understructure is in position in the mouth.

Fig. 20. The superstructure has been attached by placing the screwsin the receptacles.

286

J. Pros. I)ent. September, 1970

Wuebbenhorst

be removed, the cosmetic potential, and the confidence patients can possessby maintaining their own natural teeth. .4 minimum of special equipment is required. References 1. Ramjford, 2. Schuyler,

S. P., and Ash, M. M.: Occlusion, Philadelphia, 1966, W. B. Saunders Company. C. H.: The Function and Importance of Incisal Guidance in Oral Rehabilitation, J. PROS. DENT. 13: 1011-1029, 1963. 3. Mann, A. W., and Pankey, L. D.: Oral Rehabilitation. Part I. The Use of the I’. M. Instrument in Treatment Planning and in Restoring the Lower Posterior Teeth, J. PROS. DENT. lo: 135-150, 1960. 4. Pankey, L. D., and Mann, A. W.: Oral Rehabilitation. Part II. Reconstruction of the Upper Teeth Using a Functioning Generated Path Technique, J. PROS. DENT. 10: 151-162, 1960. 5. Overby, G. E.: Esthetic Splinting of Mobile Periodontally Involved Teeth by Vertical Pinning, J. PROS. DENT. 11: 112-l 18, 1961. 1177 N. E. 8TH DELRAY

BEACH,

ST.

FLA.

33444