- Email: [email protected]
Implant prostheses for convertibility, stress control, esthetics, and hygiene
ImDlant prostheses for convertibility, estketicsi and hygiene
stress control,
Robert E. Garfield, D.D.S. Los Angeles, Calif.
I
mplant prostheses currently in use generally fail to address four important objectives: (1) convertibility to a conventional prosthesis and/or addition of more implant fixtures if some implant fixtures fail; (2) stress control between implant fixtures splinted to natural teeth, where natural teeth have some degree of physiologic movement and implant fixtures have none; (3) esthetics approaching that obtainable with conventional prostheses, such as ceramometal’; and (4) accessto perform meticulous oral hygiene at the cervicogingival region of the implant fixture and/or the natural tooth abutment.2 The fullarch convertible periodontal prosthesis, or the sectional convertible periodontal prosthesis, can solve some of these problems (Figs. 1 through 5).3-6Convertible periodontal protheses are telescopic, detachable, snapretained, “fixed-appearing” restorations that can be converted to overlay removable partial dentures, overdentures, standard esthetic removable partial dentures, and complete dentures in a quick and systematic manner.
Convertibility
and implant addition
Implant fixtures can fail, as can natural tooth roots for various reasons. When failure occurs with cemented prostheses, or with screw-retained prostheses, and a period of time elapses before the problem is discovered, damage to otherwise stable abutments can occur, which can cause the loss of the entire prosthesis. This event usually puts a tremendous strain on the doctor-patient relationship. Modification of a prosthesis to a form that is partially soft tissue-borne or to an overdenture or complete denture can be accomplished in a precise and structured sequence that is fully understood by the patient in advance of the primary treatment. Likewise, the option for the addition of more implant fixtures to support the original prosthesis, if some abutments fail, must be understood by the patient. These options for orderly and simple modifications are greatly enhanced by the feature of quick detachability of the prosthesis by the patient. It is this feature that makes possible the attainment of the four objectives stated in the title of this article and is described in detail in the references.3-7
Stress control Unlike natural tooth roots, which have some slight movement under a masticatory load, osseointegrated THE JOURNAL
OF PROSTHETIC
DENTISTRY
implant fixtures are completely rigid. Fixed splinting of natural teeth to implant fixtures is believed by many clinicians to be undesirable because the rigidity of the implant fixture may deprive the natural abutment of physiologic stimulation. Likewise, the normally slight mobility of natural abutments may allow some leveraging forces transmitted through the fixed prosthesis to overstress the implant and possibly cause a loss of osseointegration. Tissue bar splinting of implant fixtures will present a similar problem if one implant loses its osseointegration and becomes mobile. A solution to these problems is to provide a “universal joint” connector at each abutment. This procedure can be accomplished with the Ceka attachment snap-coping or the Ceka extension attachment anchor and interlock combination (Ceka, N.V., Antwerp, Belgium) (Figs. 1 through 5).6 With the exception of overdentures, none of the present implant systems uses the snap-coping/overlay prosthesis concept that has worked so well for salvaging terminal dentitions with convertible periodontal prostheses.3However, some simple laboratory modifications to these implant systems will accomplish this result (Figs. 6 through 9, see 21).
Esthetics Most implant prostheses are esthetically deficient at the gingival third of the teeth.‘-* This is especially true with the Biotes (Branemark) system (Nobelpharma USA, Inc., Waltham, Mass.), and is primarily the result of the transmucosal connectors having a diameter and length that is out of proportion to normal tooth anatomy at the cervical end. This problem can be solved by the fabrication of custom-made cast gold transmucosal snapcopings that can be cemented intrafixturally or extrafixturally. The intrafixtural snap-coping is cemented directly into the primary implant fixture’s threaded channel (Fig. 5). This post-coping attachment abutment can be angled in any direction necessary to achieve overall parallelism, independent of the angulation of the implant fixtures. This important feature allows the surgeon to place the implant fixtures into the most ideal bone sites at whatever angulation is most stable, instead of having to compromise stability for fixture parallelism as with the conventional method. The intrafixtural snap-coping is used when the mucosal thickness overlay85
GARFIELD
Fig. 1. Full-arch convertible periodontal prostheses viewed from occlusal and gingival aspects, and sectional convertible periodontal prostheses. Fig. 2. Access for meticulous daily hygiene is enhanced by detachability of prosthesis. Fig. 3. Esthetics of an implant/tooth supported convertible periodontal prosthesis approaches that of a conventional ceramometal restoration. Fig. 4. Natural tooth-supported ceramometal units are splinted to implant-supported sectional prosthesis. First premolar retainer holds a distal interlock receptacle and a distal extension Ceka attachment female receptacle for a modified male extension assembly. Two implant copings hold Ceka male extensions.
Fig. 5. A, Radiograph of example similar to one in Fig. 4. Distal implant fixture holds extrafixtural snap-coping. Two mesial fixtures hold intrafixtural snap-copings. Note gingival embrasure on distal extension attachment on canine. B, Prosthesis in place on snap-copings.
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Fig. 6. Top: Yellow Parapost impression post fits into threaded channel of transmucosal connector screw. Bottom: Black Parapost impression post (or 14-gauge plastic sprue) fits threaded channel of implant fixture itself. Fig. 7. Stock copings are neatly waxed with sprue extensions serving as future impression indexing guides. Fig. 8. Completed “stock” copings: left, extrafixtural type; right, intrafixtural type. Fig. 9. Finished “stock” copings seated on their respective fixture laboratory dies. Fig. 10. Copings are placed onto fixtures in mouth. Fig. 11. Transfer impression is made and implant copings are placed within it. In this clinical example, Ceka H-3 transfer jig is placed in impression of one of previously existing snap-copings and is secured with sticky wax. Copings should be lubricated for an easy separation from poured and set cast.
ing the implant fixture is 3 mm or less, or when inte:rarch space is limited. \IYhen the mucosal thickness is in excessof 3 mm and inte:rarch space is sufficient, a snap-coping is made to fit extrmafixturally and cemented over the transmucosal
THE JOURNAL
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abutment connector (Fig. 5). Both of these imp1.ant snap-coping designs are prefabricated in the laborat ory in quantity for later use. The Ceka attachments are soldered onto the copings after the copings have been transferred from the mouth to a master cast (Figs. 10
87
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.
Fig. 12. Clockwise from fop: Ceka H-14A transfer jig for Ceka extracoronal extension attachments (Fig. 13); Ceka H-13A transfer instrument for use with the H-14A in pouring of impression containing H-14A; Ceka transfer instrument H-3 (see Fig. 11). These transfer instruments are for paralleling existing attachments to new attachments within same dental arch. Fig. 13. Ceka H-14A transfer instrument within an existing extracoronal extension attachment female before making of an impression for new implant snap-coping. Before pouring this impression, H-13A component will be placed onto this H-14A and thus incorporated into cast. Ceka P-2/5 surveyor mandrel will be set into this H-13A and surveyor table will be set.
through 14). As with the intrafixtural snap-coping, the extrafixtural type also allows the surgeon to disregard fixture parallelism. The application of this concept to the Core-Vent/ Screw-Vent (Core-Vent Corp., Encino, Calif.), Integral (Calcitek, Inc., San Diego, Calif.), Steri-Oss (Denar Corp., Anaheim, Calif.), and other systems is similar (See Figs. 27 through 30). Most of these systems already have a plastic healing insert that can be cast in gold. If threads are present on the “post” portion of the plastic
insert, they are lightly abraded with a disk, preserving some of their surface irregularities, so that the future snap-coping can be cemented to place into the threaded implant channel by using any composite cementing agent. In all instances, the custom-cast gold transmucosal connectors can be given the most appropriate
diameter
that will achieve the best esthetic effect for the particular retainer overlay. As a further advantage of daily (or multidaily)
detachment of the prosthesis by the patient,
Fig. 14. Set cast from Fig. 11 containing three transfered implant copings and H-3 transfer instrument for paralleling existing snap-copings to new implant copings. Before removal of stock implant copings from cast, gingival margins in artificial stone are lightly scraped and festooned and all artifacts removed. A vertical orientation groove is placed on all implant copings with a No. % round bur on mesial surface of coping. Fig. 15. Male extension pin is removed from H-3 instrument and replaced with Ceka P-4 surveyor mandrel. Surveyor table can be set to verticalize this mandrel. Fig. 16. Indexing extensions are cut off of implant copings at desired height and Ceka No. 691 base ring is positioned over coping. Fig. 17. Duralay resin or sticky wax is used to attach Ceka base ring to implant coping prior to investing for soldering. Fig. 18. Ceka H-4 soldering aid instrument with base ring and implant coping ready for investing. Fig. 19. Soldering investment must cover vertical orientation groove so that solder will not destroy it. No. 615 gold solder is used with borax flux. Fig. 20. Soldered and finished copings replaced and checked on master model. Note mesial position of vertical orientation groove. This groove will enable operator to cement copings in correct position relative to their angle of attachment draw. Fig. 21. Top: Completed extrafixtural snap-coping with extension pin screwed to place; botfom, completed intrafixtural snap-coping. Note presence of cement escape vent on extrafixtural snap-coping. Tight fit of coping to transmucosal connector demands this vent. 88
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See opposite page for legends. cervixcal contours of the overlaying prosthesis units need not “fit” the snap-coping transmucosal conneck rs, thereby giving esthetic options not possible with cemented prostheses (Figs. 1 through 3; see Fig.
26). THE JOURNAL
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Hygiene No substitute has been found for meticulous daily plaque removal in the struggle to improve implant longevity.8 Meticulous plaque removal from the cervical surface of natural tooth abutments and implant abut89
See opposite page for legends.
ments is enhanced by the accessprovided by the frequent detaching of the prosthesis. Access for the toothbrush is easier and more effective (Fig. 2). Periodontal therapy can be performed more efficiently and more successfully 90
with convertible periodontal prostheses. Healthy, noninflamed gingival tissues add to the longevity of natural tooth abutments and possibly to implants and are more esthetically pleasing. JULY 1988
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FABRICATION OF IMPLANT SNAP-COPINGS Biotes (Branemark) system without transmucosal connector (intrafixtural) An implant fixture of at least 10 mm length is used as a die in the laboratory. Either a 1Cgauge plastic sprue (Williams Gold Refining Co. Inc., Buffalo, N.Y.) or a black (0.060 inch) Para-Post plastic impression post (Whaledent International, New York, N.Y.) is lightly coated with wax and inserted into the threaded channel of the implant (Fig. 6). The wax coating will prevent the expanding plastic post pattern from fracturing the investment during burnout. Inlay wax is adapted over the hex head at the channel orifice and built up to form the desired shape for the transmucosal portion of the post coping (Fig. 7). Tl le wax margins are finished with a slight excessof wax over the occlusal rim of the implant. The extending end of the post at the occlusal end is shaped with wax to become half-round on cross section so that the casting will later key to the transfer impression from the mouth (Fig. 11). Several of these wax patterns are made and cast in type IV gold (Laboratory 44, J.F. Jelenko & Co., Armonk, N.Y.) (Fig. 8, right). They are finished to correctly seat back on the fixture die (Fig. 9). The post-copings are placed into the fixture channels in the mouth and an impression is made. After removal of the impression, the copings are removed, lubricated, and replaced in the impression. A master cast is poured (Figs. 11 and 14). After transferring the post-copings from the impression to the master cast and cutting off the indexing extension, the Ceka base ring is attached with sticky wax
or Duralay (Reliance Dental Mfg. Co., Worth, Ill.) at the desired angle of draw for the prosthesis. The Ceka P-4 mandrel and a surveyor are used to hold and position the base ring (Figs. 14 through 17).” A seating orientation mark is placed (Fig. 14). If snap-copings already exist in the arch from previous treatment, the Ceka paralleling transfer aids (jigs) H-14A, H-13A, and H-3 are used to make the new snap-copings parallel to the existing ones (Figs. 11 through 17). The entire assembly is removed from the master cast and invested for soldering using the Ceka H-4 soldering aid (Figs. 18 and 19).’ After soldering, contouring, and polishing, the snap-coping is returned to its position in the master cast. The seating orientation mark may require redefining at this time. A thin disk will accomplish this task (Fig. 20), allowing the snap-coping to be correctly positioned during cementation and ensuring that it will be parallel with the other attachments.
Biotes (Branemark) system with transmucosal connector (extrafixtural) An implant fixture with a transmucosal connector screwed into place is used in the laboratory as a die. Small sized transmucosal connectors (2 mm or 4 mm) are applicable in most situations. Occasionally a connector of greater length may be used in the mouth; however, the smaller size is adequate for retentive length in making the coping pattern. Good frictional retention is achieved between the coping and the transmucosal connector, provided that the wax pattern is adapted well. The parallel sides of the connector and the metalto-metal interface create adequate retention for the
Fig. 22. Implant
snap-copings ready for cementation with male extension pins removed. Soiled implant fixtures shown here are used over and over to make more stock copings in laboratory. Fig. 23. Cementation is performed by holding coping with a modified Ceka P-4 surveyor mandrel with its shaft cut off. H-2 and H-16 accessory instruments can also be used for holding coping during cementation. With intrafixtural post-coping, spiral cement filler in handpiece is necessary to deliver cement into primary fixture channel. Fig. 24. Full-mouth restoration with snap-copings attached to Biotes implant fixtures and to natural tooth roots. Splinting is achieved by overlay detachable telescopic prostheses (convertible periodontal prostheses). Fig. 25. Radiograph of patient in Fig. 24. Maxillary snap-copings are extrafixtural type. Mandibular implant copings are intrafixtural. Fig. 26. Subject in Figs. 24 and 25 with convertible periodontal prostheses supported by natural tooth roots and Biotes implant fixtures. Fig. 27. Core-Vent plastic coping insert (XI). Fig. 28. Core-Vent plastic coping insert can be modified by cutting with a disk. Fig. 29. Top: Core-Vent PC1 modified and ready for casting in gold. Bottom: Finished Core-Vent implant snap-coping. Fig. 30. Plastic healing insert for Integral implant can be used in same manner as Core-Vent PC1 in Figs. 27 through 29. THE JOURNAL
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GARFIELD
coping, especially when used with glass ionomer, resin, and polycarboxylate cements. A yellow (0.040 inch) Para-Post plastic impression post is lightly coated with wax and inserted into the threaded channel of the transmucosal connector screw (Fig. 6, top). As with the intrafixtural post-coping, the very thin wax coating over the plastic post pattern will prevent the post pattern from fracturing the investment by expanding during burnout. The investment is vulnerable to fracture in the neck region, where the post meets the occlusal portion of the coping. The coping part of the wax pattern is extended gingivally on the transmucosal connector all the way to the bevel. The half-round-shaped indexing extension is waxed around the extending Para-Post pattern and formed into the sprue for investing (Fig. 7, top). After casting in type IV gold, the copings are finished and fitted to the fixture-connector die (Fig. 9, tom). The remainder of the procedure is identical to that described for the intrafixtural post-copings (Figs. 10 through 22). A large supply of both intrafixtural and extrafixtural post-copings can be made and stored for later use with the Biotes implant system. The attachments can be soldered onto the copings as each individual treatment situation presents itself. CORE-VENT
AND SCREW-VENT
SYSTEMS
The snap-copings for the Core-Vent/Screw-Vent systems are similar to those for the Biotes system. However, the Core-Vent plastic coping insert (PCI) is shaped like the traditional implant abutment extension (see Fig. 27). The extension portion is cut away and the remaining post and neck are cast in type IV gold (see Fig. 28). The sprue is used to form the indexing extension. The Ceka attachment, or any other snap-type attachment is soldered on as is shown with the Biotes System (see Fig. 29). INTEGRAL
SYSTEM
The integral implant system usesa plastic healing cuff that screws either directly into the implant fixture or into the transmucosal extension (see Fig. 30). The cuffs can be cut and modified with wax to form indexing extensions. They are then invested and cast in type IV gold. After casting, the threads on the screw portion are lightly abraded with a disk until the post-coping will “draw” with some frictional retention from the implant fixture die. Despite the shortness of the post portion of this coping, retention to the implant in the mouth is adequate. The irregularities from the former screw threads interfacing with the channel threading of the implant provide sufficient retention when cemented with composite cement. Extrafixtural snap-copings are also possible on these other systems. 92
CEMENTATION
.
OF SNAP-COPINGS
A Ceka P-4 surveyor mandrel with its shaft cut off, or a Ceka H-16 mandrel is used to hold and seat the snap-copings during cementation (Fig. 23).6 The mandrel must be screwed tightly into the threads of the coping base ring to ensure that it will not loosen during& the cementation procedure. The vertical seating orientation mark on the mesial of the snap-coping must be ’ clearly visible throughout this procedure. Otherwise the copings will not be oriented so that all of the male extensions are parallel to each other in the manner that they were designed to be from the surveyor (Figs. 24 and 25). A slight deviation from perfect parallelism (5 to 7 L degrees) can be tolerated by the attachment, provided that the units are not close together, as adjacent teeth would be. If the extrafixtural snap-coping is being cemented onto a transmucosal connector, the connector screw must be checked for tightness at this time and+ tightened to its limit. A lentulo spiral cement filling instrument (Union Broach) Corp., Long Island City, N.Y.) in the low-speed handpiece is used to carry cement into the implant channels.6 Cement is placed inside of the coping margins and the copings are seated to place. When a snap-coping is being cemented over a Biotes transmucosal connector, a small escapevent must be used to ensure full seating of the coping. This is accomplished with a No. % round bur I at the occlusoaxial angle of the coping and need not be repaired after cementation because caries is not a problem here. After the cement has set, the attachment extensions may be screwed into place in the coping base rings. The * spacer washers and receptacles are placed over the extensions. The temporary restoration is then relieved to accommodate the snap-copings. Frequently the temporary restoration can be attached to the snap-coping system at this time.3B4 After a short healing period, when the soft tissues ” adjacent to the implant-snap-coping assembly have assumed their normal contour, a master impression may be made of the arch for proceeding with the final restoration.‘-’ l
,I
SUMMARY
A method of connecting “fixed partial denture” prostheses to osseointegrated implant fixtures has been described. The advantages of this system of restoration for partially and fully edentulous mouths are that it is more effective in addressing the problems of (1) stresscontrol on abutments, (2) a back-up system for abutment * failures, (3) esthetics, and (4) control of bacterial plaques around abutments. To accomplish this procedure, the application of convertible periodontal prosthesis techniques with modifications to some existing implant systems is undertaken.3-6 JULY 1988
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The disadvantages of this method seem insignificant when one considers the complexities and risks involved with the present array of implant prosthesis alternatives. Some patients and dentists might consider the necessity of the prosthesis being detachable as one disadvantage. In reality, the prosthesis can be used as a fixed restoration until the patient has fully adapted to the new proprioception and appearance. A large percentage of patients feel uncomfortable with the word “removable” because it immediately creates a perception of unsightly metallic clasp display, palatal coverage, tongue interference, and negative body image. The use of the term “detachable” coupled with the doctor’s offer to perform this task for the patient “whenever necessary” will usually relieve the patient’s anxiety and allow the treatment to proceed. Once neuromuscular and esthetic adaptation have occurred and the patient has accepted the prosthesis, daily detaching and home-care hygiene by the patient will follow without incident. Esthetic improvement is obvious (Fig. 3). REFERENCES I.
PR~~THET DENT 1986;55:243-7.
3. Garfield RE. Salvaging terminal dentitions with convertible periodontal prostheses. J PROSTHET DENT 1980;43:521-6. 4. Garfield RE. Clinical and laboratory procedures for the construction and maintenance of the convertible periodontal prosthesis. Quintessence International 1981; Atlas section, I-V, Mar-
July. 5. Garfield RE. A prosthetic solution to the periodontally compromised/furcation involved abutment tooth. Quintessence International 1984; Atlas section, I&II, Aug, Sept. 6. Garfield RE. Fabrication of retainer castings for convertibledetachable prostheses and overdentures utilizing Ceka attachments. Quintessence of Dental Technology 1984;July/Aug, Sept. I. American Association of Oral and Maxillofacial Surgeons. Surgical Update 1986-7;2:Issue 3, Winter, 2. 8. Pare1 SM, Balshi TJ, Sullivan DY, Cardenas ER. Gingival augmentation for osseointegrated implant prostheses. J PROSTHET DENT 1986;56:208-11.
Reprint requests to: DR. ROBERT E. GARFIELD 10921 WILSHIRE BLVD., STE. 505 Los ANGELES. CA 90024-3974
Loos LG. A fixed prosthodontic technique for mandibular osseointegrated titanium implants. J PROSTHET DENT 1986; 55:232-42.
Bound I
2. Jemt T. Modified single and short-span restorations supported by osseointegrated fixtures in the partially edentulous jaw. J
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JOURNAL
THE JOURNAL
OF PROSTHETIC
DENTISTRY
93
stress control,
Robert E. Garfield, D.D.S. Los Angeles, Calif.
I
mplant prostheses currently in use generally fail to address four important objectives: (1) convertibility to a conventional prosthesis and/or addition of more implant fixtures if some implant fixtures fail; (2) stress control between implant fixtures splinted to natural teeth, where natural teeth have some degree of physiologic movement and implant fixtures have none; (3) esthetics approaching that obtainable with conventional prostheses, such as ceramometal’; and (4) accessto perform meticulous oral hygiene at the cervicogingival region of the implant fixture and/or the natural tooth abutment.2 The fullarch convertible periodontal prosthesis, or the sectional convertible periodontal prosthesis, can solve some of these problems (Figs. 1 through 5).3-6Convertible periodontal protheses are telescopic, detachable, snapretained, “fixed-appearing” restorations that can be converted to overlay removable partial dentures, overdentures, standard esthetic removable partial dentures, and complete dentures in a quick and systematic manner.
Convertibility
and implant addition
Implant fixtures can fail, as can natural tooth roots for various reasons. When failure occurs with cemented prostheses, or with screw-retained prostheses, and a period of time elapses before the problem is discovered, damage to otherwise stable abutments can occur, which can cause the loss of the entire prosthesis. This event usually puts a tremendous strain on the doctor-patient relationship. Modification of a prosthesis to a form that is partially soft tissue-borne or to an overdenture or complete denture can be accomplished in a precise and structured sequence that is fully understood by the patient in advance of the primary treatment. Likewise, the option for the addition of more implant fixtures to support the original prosthesis, if some abutments fail, must be understood by the patient. These options for orderly and simple modifications are greatly enhanced by the feature of quick detachability of the prosthesis by the patient. It is this feature that makes possible the attainment of the four objectives stated in the title of this article and is described in detail in the references.3-7
Stress control Unlike natural tooth roots, which have some slight movement under a masticatory load, osseointegrated THE JOURNAL
OF PROSTHETIC
DENTISTRY
implant fixtures are completely rigid. Fixed splinting of natural teeth to implant fixtures is believed by many clinicians to be undesirable because the rigidity of the implant fixture may deprive the natural abutment of physiologic stimulation. Likewise, the normally slight mobility of natural abutments may allow some leveraging forces transmitted through the fixed prosthesis to overstress the implant and possibly cause a loss of osseointegration. Tissue bar splinting of implant fixtures will present a similar problem if one implant loses its osseointegration and becomes mobile. A solution to these problems is to provide a “universal joint” connector at each abutment. This procedure can be accomplished with the Ceka attachment snap-coping or the Ceka extension attachment anchor and interlock combination (Ceka, N.V., Antwerp, Belgium) (Figs. 1 through 5).6 With the exception of overdentures, none of the present implant systems uses the snap-coping/overlay prosthesis concept that has worked so well for salvaging terminal dentitions with convertible periodontal prostheses.3However, some simple laboratory modifications to these implant systems will accomplish this result (Figs. 6 through 9, see 21).
Esthetics Most implant prostheses are esthetically deficient at the gingival third of the teeth.‘-* This is especially true with the Biotes (Branemark) system (Nobelpharma USA, Inc., Waltham, Mass.), and is primarily the result of the transmucosal connectors having a diameter and length that is out of proportion to normal tooth anatomy at the cervical end. This problem can be solved by the fabrication of custom-made cast gold transmucosal snapcopings that can be cemented intrafixturally or extrafixturally. The intrafixtural snap-coping is cemented directly into the primary implant fixture’s threaded channel (Fig. 5). This post-coping attachment abutment can be angled in any direction necessary to achieve overall parallelism, independent of the angulation of the implant fixtures. This important feature allows the surgeon to place the implant fixtures into the most ideal bone sites at whatever angulation is most stable, instead of having to compromise stability for fixture parallelism as with the conventional method. The intrafixtural snap-coping is used when the mucosal thickness overlay85
GARFIELD
Fig. 1. Full-arch convertible periodontal prostheses viewed from occlusal and gingival aspects, and sectional convertible periodontal prostheses. Fig. 2. Access for meticulous daily hygiene is enhanced by detachability of prosthesis. Fig. 3. Esthetics of an implant/tooth supported convertible periodontal prosthesis approaches that of a conventional ceramometal restoration. Fig. 4. Natural tooth-supported ceramometal units are splinted to implant-supported sectional prosthesis. First premolar retainer holds a distal interlock receptacle and a distal extension Ceka attachment female receptacle for a modified male extension assembly. Two implant copings hold Ceka male extensions.
Fig. 5. A, Radiograph of example similar to one in Fig. 4. Distal implant fixture holds extrafixtural snap-coping. Two mesial fixtures hold intrafixtural snap-copings. Note gingival embrasure on distal extension attachment on canine. B, Prosthesis in place on snap-copings.
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Fig. 6. Top: Yellow Parapost impression post fits into threaded channel of transmucosal connector screw. Bottom: Black Parapost impression post (or 14-gauge plastic sprue) fits threaded channel of implant fixture itself. Fig. 7. Stock copings are neatly waxed with sprue extensions serving as future impression indexing guides. Fig. 8. Completed “stock” copings: left, extrafixtural type; right, intrafixtural type. Fig. 9. Finished “stock” copings seated on their respective fixture laboratory dies. Fig. 10. Copings are placed onto fixtures in mouth. Fig. 11. Transfer impression is made and implant copings are placed within it. In this clinical example, Ceka H-3 transfer jig is placed in impression of one of previously existing snap-copings and is secured with sticky wax. Copings should be lubricated for an easy separation from poured and set cast.
ing the implant fixture is 3 mm or less, or when inte:rarch space is limited. \IYhen the mucosal thickness is in excessof 3 mm and inte:rarch space is sufficient, a snap-coping is made to fit extrmafixturally and cemented over the transmucosal
THE JOURNAL
OF PROSTHETIC
DENTISTRY
abutment connector (Fig. 5). Both of these imp1.ant snap-coping designs are prefabricated in the laborat ory in quantity for later use. The Ceka attachments are soldered onto the copings after the copings have been transferred from the mouth to a master cast (Figs. 10
87
GARFIELD
.
Fig. 12. Clockwise from fop: Ceka H-14A transfer jig for Ceka extracoronal extension attachments (Fig. 13); Ceka H-13A transfer instrument for use with the H-14A in pouring of impression containing H-14A; Ceka transfer instrument H-3 (see Fig. 11). These transfer instruments are for paralleling existing attachments to new attachments within same dental arch. Fig. 13. Ceka H-14A transfer instrument within an existing extracoronal extension attachment female before making of an impression for new implant snap-coping. Before pouring this impression, H-13A component will be placed onto this H-14A and thus incorporated into cast. Ceka P-2/5 surveyor mandrel will be set into this H-13A and surveyor table will be set.
through 14). As with the intrafixtural snap-coping, the extrafixtural type also allows the surgeon to disregard fixture parallelism. The application of this concept to the Core-Vent/ Screw-Vent (Core-Vent Corp., Encino, Calif.), Integral (Calcitek, Inc., San Diego, Calif.), Steri-Oss (Denar Corp., Anaheim, Calif.), and other systems is similar (See Figs. 27 through 30). Most of these systems already have a plastic healing insert that can be cast in gold. If threads are present on the “post” portion of the plastic
insert, they are lightly abraded with a disk, preserving some of their surface irregularities, so that the future snap-coping can be cemented to place into the threaded implant channel by using any composite cementing agent. In all instances, the custom-cast gold transmucosal connectors can be given the most appropriate
diameter
that will achieve the best esthetic effect for the particular retainer overlay. As a further advantage of daily (or multidaily)
detachment of the prosthesis by the patient,
Fig. 14. Set cast from Fig. 11 containing three transfered implant copings and H-3 transfer instrument for paralleling existing snap-copings to new implant copings. Before removal of stock implant copings from cast, gingival margins in artificial stone are lightly scraped and festooned and all artifacts removed. A vertical orientation groove is placed on all implant copings with a No. % round bur on mesial surface of coping. Fig. 15. Male extension pin is removed from H-3 instrument and replaced with Ceka P-4 surveyor mandrel. Surveyor table can be set to verticalize this mandrel. Fig. 16. Indexing extensions are cut off of implant copings at desired height and Ceka No. 691 base ring is positioned over coping. Fig. 17. Duralay resin or sticky wax is used to attach Ceka base ring to implant coping prior to investing for soldering. Fig. 18. Ceka H-4 soldering aid instrument with base ring and implant coping ready for investing. Fig. 19. Soldering investment must cover vertical orientation groove so that solder will not destroy it. No. 615 gold solder is used with borax flux. Fig. 20. Soldered and finished copings replaced and checked on master model. Note mesial position of vertical orientation groove. This groove will enable operator to cement copings in correct position relative to their angle of attachment draw. Fig. 21. Top: Completed extrafixtural snap-coping with extension pin screwed to place; botfom, completed intrafixtural snap-coping. Note presence of cement escape vent on extrafixtural snap-coping. Tight fit of coping to transmucosal connector demands this vent. 88
JULY 1988
VOLUME
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NUMBER
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PROSTHESES
See opposite page for legends. cervixcal contours of the overlaying prosthesis units need not “fit” the snap-coping transmucosal conneck rs, thereby giving esthetic options not possible with cemented prostheses (Figs. 1 through 3; see Fig.
26). THE JOURNAL
OF PROSTHETIC
DENTISTRY
Hygiene No substitute has been found for meticulous daily plaque removal in the struggle to improve implant longevity.8 Meticulous plaque removal from the cervical surface of natural tooth abutments and implant abut89
See opposite page for legends.
ments is enhanced by the accessprovided by the frequent detaching of the prosthesis. Access for the toothbrush is easier and more effective (Fig. 2). Periodontal therapy can be performed more efficiently and more successfully 90
with convertible periodontal prostheses. Healthy, noninflamed gingival tissues add to the longevity of natural tooth abutments and possibly to implants and are more esthetically pleasing. JULY 1988
VOLUME
60
NUMBER
1
IMPLANT
PROSTHESES
FABRICATION OF IMPLANT SNAP-COPINGS Biotes (Branemark) system without transmucosal connector (intrafixtural) An implant fixture of at least 10 mm length is used as a die in the laboratory. Either a 1Cgauge plastic sprue (Williams Gold Refining Co. Inc., Buffalo, N.Y.) or a black (0.060 inch) Para-Post plastic impression post (Whaledent International, New York, N.Y.) is lightly coated with wax and inserted into the threaded channel of the implant (Fig. 6). The wax coating will prevent the expanding plastic post pattern from fracturing the investment during burnout. Inlay wax is adapted over the hex head at the channel orifice and built up to form the desired shape for the transmucosal portion of the post coping (Fig. 7). Tl le wax margins are finished with a slight excessof wax over the occlusal rim of the implant. The extending end of the post at the occlusal end is shaped with wax to become half-round on cross section so that the casting will later key to the transfer impression from the mouth (Fig. 11). Several of these wax patterns are made and cast in type IV gold (Laboratory 44, J.F. Jelenko & Co., Armonk, N.Y.) (Fig. 8, right). They are finished to correctly seat back on the fixture die (Fig. 9). The post-copings are placed into the fixture channels in the mouth and an impression is made. After removal of the impression, the copings are removed, lubricated, and replaced in the impression. A master cast is poured (Figs. 11 and 14). After transferring the post-copings from the impression to the master cast and cutting off the indexing extension, the Ceka base ring is attached with sticky wax
or Duralay (Reliance Dental Mfg. Co., Worth, Ill.) at the desired angle of draw for the prosthesis. The Ceka P-4 mandrel and a surveyor are used to hold and position the base ring (Figs. 14 through 17).” A seating orientation mark is placed (Fig. 14). If snap-copings already exist in the arch from previous treatment, the Ceka paralleling transfer aids (jigs) H-14A, H-13A, and H-3 are used to make the new snap-copings parallel to the existing ones (Figs. 11 through 17). The entire assembly is removed from the master cast and invested for soldering using the Ceka H-4 soldering aid (Figs. 18 and 19).’ After soldering, contouring, and polishing, the snap-coping is returned to its position in the master cast. The seating orientation mark may require redefining at this time. A thin disk will accomplish this task (Fig. 20), allowing the snap-coping to be correctly positioned during cementation and ensuring that it will be parallel with the other attachments.
Biotes (Branemark) system with transmucosal connector (extrafixtural) An implant fixture with a transmucosal connector screwed into place is used in the laboratory as a die. Small sized transmucosal connectors (2 mm or 4 mm) are applicable in most situations. Occasionally a connector of greater length may be used in the mouth; however, the smaller size is adequate for retentive length in making the coping pattern. Good frictional retention is achieved between the coping and the transmucosal connector, provided that the wax pattern is adapted well. The parallel sides of the connector and the metalto-metal interface create adequate retention for the
Fig. 22. Implant
snap-copings ready for cementation with male extension pins removed. Soiled implant fixtures shown here are used over and over to make more stock copings in laboratory. Fig. 23. Cementation is performed by holding coping with a modified Ceka P-4 surveyor mandrel with its shaft cut off. H-2 and H-16 accessory instruments can also be used for holding coping during cementation. With intrafixtural post-coping, spiral cement filler in handpiece is necessary to deliver cement into primary fixture channel. Fig. 24. Full-mouth restoration with snap-copings attached to Biotes implant fixtures and to natural tooth roots. Splinting is achieved by overlay detachable telescopic prostheses (convertible periodontal prostheses). Fig. 25. Radiograph of patient in Fig. 24. Maxillary snap-copings are extrafixtural type. Mandibular implant copings are intrafixtural. Fig. 26. Subject in Figs. 24 and 25 with convertible periodontal prostheses supported by natural tooth roots and Biotes implant fixtures. Fig. 27. Core-Vent plastic coping insert (XI). Fig. 28. Core-Vent plastic coping insert can be modified by cutting with a disk. Fig. 29. Top: Core-Vent PC1 modified and ready for casting in gold. Bottom: Finished Core-Vent implant snap-coping. Fig. 30. Plastic healing insert for Integral implant can be used in same manner as Core-Vent PC1 in Figs. 27 through 29. THE JOURNAL
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DENTISTRY
91
GARFIELD
coping, especially when used with glass ionomer, resin, and polycarboxylate cements. A yellow (0.040 inch) Para-Post plastic impression post is lightly coated with wax and inserted into the threaded channel of the transmucosal connector screw (Fig. 6, top). As with the intrafixtural post-coping, the very thin wax coating over the plastic post pattern will prevent the post pattern from fracturing the investment by expanding during burnout. The investment is vulnerable to fracture in the neck region, where the post meets the occlusal portion of the coping. The coping part of the wax pattern is extended gingivally on the transmucosal connector all the way to the bevel. The half-round-shaped indexing extension is waxed around the extending Para-Post pattern and formed into the sprue for investing (Fig. 7, top). After casting in type IV gold, the copings are finished and fitted to the fixture-connector die (Fig. 9, tom). The remainder of the procedure is identical to that described for the intrafixtural post-copings (Figs. 10 through 22). A large supply of both intrafixtural and extrafixtural post-copings can be made and stored for later use with the Biotes implant system. The attachments can be soldered onto the copings as each individual treatment situation presents itself. CORE-VENT
AND SCREW-VENT
SYSTEMS
The snap-copings for the Core-Vent/Screw-Vent systems are similar to those for the Biotes system. However, the Core-Vent plastic coping insert (PCI) is shaped like the traditional implant abutment extension (see Fig. 27). The extension portion is cut away and the remaining post and neck are cast in type IV gold (see Fig. 28). The sprue is used to form the indexing extension. The Ceka attachment, or any other snap-type attachment is soldered on as is shown with the Biotes System (see Fig. 29). INTEGRAL
SYSTEM
The integral implant system usesa plastic healing cuff that screws either directly into the implant fixture or into the transmucosal extension (see Fig. 30). The cuffs can be cut and modified with wax to form indexing extensions. They are then invested and cast in type IV gold. After casting, the threads on the screw portion are lightly abraded with a disk until the post-coping will “draw” with some frictional retention from the implant fixture die. Despite the shortness of the post portion of this coping, retention to the implant in the mouth is adequate. The irregularities from the former screw threads interfacing with the channel threading of the implant provide sufficient retention when cemented with composite cement. Extrafixtural snap-copings are also possible on these other systems. 92
CEMENTATION
.
OF SNAP-COPINGS
A Ceka P-4 surveyor mandrel with its shaft cut off, or a Ceka H-16 mandrel is used to hold and seat the snap-copings during cementation (Fig. 23).6 The mandrel must be screwed tightly into the threads of the coping base ring to ensure that it will not loosen during& the cementation procedure. The vertical seating orientation mark on the mesial of the snap-coping must be ’ clearly visible throughout this procedure. Otherwise the copings will not be oriented so that all of the male extensions are parallel to each other in the manner that they were designed to be from the surveyor (Figs. 24 and 25). A slight deviation from perfect parallelism (5 to 7 L degrees) can be tolerated by the attachment, provided that the units are not close together, as adjacent teeth would be. If the extrafixtural snap-coping is being cemented onto a transmucosal connector, the connector screw must be checked for tightness at this time and+ tightened to its limit. A lentulo spiral cement filling instrument (Union Broach) Corp., Long Island City, N.Y.) in the low-speed handpiece is used to carry cement into the implant channels.6 Cement is placed inside of the coping margins and the copings are seated to place. When a snap-coping is being cemented over a Biotes transmucosal connector, a small escapevent must be used to ensure full seating of the coping. This is accomplished with a No. % round bur I at the occlusoaxial angle of the coping and need not be repaired after cementation because caries is not a problem here. After the cement has set, the attachment extensions may be screwed into place in the coping base rings. The * spacer washers and receptacles are placed over the extensions. The temporary restoration is then relieved to accommodate the snap-copings. Frequently the temporary restoration can be attached to the snap-coping system at this time.3B4 After a short healing period, when the soft tissues ” adjacent to the implant-snap-coping assembly have assumed their normal contour, a master impression may be made of the arch for proceeding with the final restoration.‘-’ l
,I
SUMMARY
A method of connecting “fixed partial denture” prostheses to osseointegrated implant fixtures has been described. The advantages of this system of restoration for partially and fully edentulous mouths are that it is more effective in addressing the problems of (1) stresscontrol on abutments, (2) a back-up system for abutment * failures, (3) esthetics, and (4) control of bacterial plaques around abutments. To accomplish this procedure, the application of convertible periodontal prosthesis techniques with modifications to some existing implant systems is undertaken.3-6 JULY 1988
VOLUME
60
NUMBER
1
IMPLANT
PROSTHESES
The disadvantages of this method seem insignificant when one considers the complexities and risks involved with the present array of implant prosthesis alternatives. Some patients and dentists might consider the necessity of the prosthesis being detachable as one disadvantage. In reality, the prosthesis can be used as a fixed restoration until the patient has fully adapted to the new proprioception and appearance. A large percentage of patients feel uncomfortable with the word “removable” because it immediately creates a perception of unsightly metallic clasp display, palatal coverage, tongue interference, and negative body image. The use of the term “detachable” coupled with the doctor’s offer to perform this task for the patient “whenever necessary” will usually relieve the patient’s anxiety and allow the treatment to proceed. Once neuromuscular and esthetic adaptation have occurred and the patient has accepted the prosthesis, daily detaching and home-care hygiene by the patient will follow without incident. Esthetic improvement is obvious (Fig. 3). REFERENCES I.
PR~~THET DENT 1986;55:243-7.
3. Garfield RE. Salvaging terminal dentitions with convertible periodontal prostheses. J PROSTHET DENT 1980;43:521-6. 4. Garfield RE. Clinical and laboratory procedures for the construction and maintenance of the convertible periodontal prosthesis. Quintessence International 1981; Atlas section, I-V, Mar-
July. 5. Garfield RE. A prosthetic solution to the periodontally compromised/furcation involved abutment tooth. Quintessence International 1984; Atlas section, I&II, Aug, Sept. 6. Garfield RE. Fabrication of retainer castings for convertibledetachable prostheses and overdentures utilizing Ceka attachments. Quintessence of Dental Technology 1984;July/Aug, Sept. I. American Association of Oral and Maxillofacial Surgeons. Surgical Update 1986-7;2:Issue 3, Winter, 2. 8. Pare1 SM, Balshi TJ, Sullivan DY, Cardenas ER. Gingival augmentation for osseointegrated implant prostheses. J PROSTHET DENT 1986;56:208-11.
Reprint requests to: DR. ROBERT E. GARFIELD 10921 WILSHIRE BLVD., STE. 505 Los ANGELES. CA 90024-3974
Loos LG. A fixed prosthodontic technique for mandibular osseointegrated titanium implants. J PROSTHET DENT 1986; 55:232-42.
Bound I
2. Jemt T. Modified single and short-span restorations supported by osseointegrated fixtures in the partially edentulous jaw. J
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