Customized Abutments to Shape and Transfer Peri-Implant Soft-Tissue Contours

Lambert J. Stumpel, III, DDS; Walter Haechler, MDT; and Edmond Bedrossian, DDS

Copyright 2000 Journal of the California Dental Association

With the functional successes of implant therapy (being realized) assumed, the emphasis is shifting to creating (to the creation of) tooth-like esthetics with implant therapy. Dental implants are placed after careful planning and site preparation, which may include bone and soft tissue grafting. The final soft tissue appearance is enhanced through the early use of provisional restorations. A combination technique is described to fabricate provisional healing abutments for cement-on prostheses and (to) transfer the individualized peri-implant soft-tissue contours to the dental laboratory. This technique will allow the practitioner to deliver highly customized implant care with familiar techniques and readily available materials.

Implant therapy has evolved greatly since its inception.¹ Dental professionals have become accustomed to the successes attainable on a functional level and are increasing their expectations with regard to esthetics. Dentists and their patients expect implant restorations to look and feel like natural teeth. (The) Differences between the position and shape of teeth as opposed to (when compared with) implants (illustrates the) create challenge(s) for the practitioner trying to create the "invisible" restoration.² As expectations have increased, therapies have evolved from fixed hybrids to single teeth and from standard to fully customized abutments. If dentists want their restoration to look like natural teeth, they will have to restore all the parameters that make up a natural esthetic. Emergence profiles must coincide, as must gingival contours. Since most of the time there is quite a difference between the dentulous and edentulous site, a myriad of techniques are used to prepare the site to mimic the dentulous environment, including bone grafting, different size implants, individualized prosthetics, and soft tissue grafting. With these techniques comes increased interest in soft-tissue contouring and transferring methods.^3-10 The objective of this article is to present a simple, predictable technique to contour soft tissue and transfer this contour to the dental laboratory by utilizing standard components and familiar techniques, thereby minimizing the number of components and (the) size of the armamentarium. The simplified technique enables more patients to receive the benefits of the state of the art in dental implant therapy.

Rationale

The position and shape of the prosthetic tooth is determined by a verified wax-up of the missing tooth structure. This information is used to fabricate the surgical stent that will guide the placement of the fixtures into the ideal position. During the presurgical work-up, deficient structures are evaluated. Three tissue types are considered. The first type is the missing tooth: The position and shape of the restoration is determined by the existing dentition. The second type is the hard tissue. If there is any question as to the volume of bone present, the width of the residual alveolus can be evaluated in the third dimension using either CT scans or tomography. The third type is the soft tissue. The evaluation of the soft tissue includes the position of the papillae adjacent to the edentulous area, the width of the attached gingiva, and the thickness of the gingiva. In treatment-planning and the execution of the surgical care, specific management of all three tissue types is considered. Additional surgical techniques can be employed to re-establish the most ideal topography in conjunction with the actual fixture placement. Site preparation and enhancement techniques of the hard and soft tissue before and after fixture placement set the stage for the prosthetic tissue contouring and reconstruction. The implant is merely a receptacle for the prosthesis. It must be placed apical to the cementoenamel junction of the adjacent teeth to allow adequate distance for the flaring of the prosthesis from the circular platform of the implant to the contact point of the adjacent dentition. It must allow for tooth contours and draping of the frame of surrounding soft tissue in a natural-appearing matter. Provisional restorations are essential in establishing smile lines and phonetics. Provisional abutments are created to guide and support the peri-implant soft tissue during healing, and they function as blueprints for the final custom abutments.

Technique

The Custom Abutment

1. The exact wax up of the missing tooth structure (Figure 1), with a clear demarcation of the cementoenamel junction, is transferred onto the cast of the fixture position (check that this is what he wrote "fixture position"). The impression for this cast may be obtained at fixture placement¹⁰ or within a few days after second-stage surgery, depending on logistics and team preference. With the cast made at fixture placement, the restorative team has a few months available to fabricate the temporary reconstruction before it will be placed by the surgeon as a functional temporary unit at second-stage surgery. Time is of the essence when the impression is taken shortly after the second-stage surgery, however, since the temporary assembly needs to be placed within a few days to guide the healing in mature soft tissue.

Figure 1. The wax up of missing tooth structure. The cast is obtained from the impression taken during stage I surgery.

2. A titanium temporary cylinder is treated to establish a bonding surface for the composite. Surface treatment may consist of Silicoating and opaqueing (Heraeus Kulzer, Inc., Irvine, Calif.).^12,13 Plastic temporary cylinders are available, but they lack dependable chemical bonding capability with composite and are more difficult to positively reposition onto the oral fixture head.

3. The custom cylinder is placed on the laboratory fixture analog of the cast, and bonding agent is applied to it. A matrix of the wax-up is fabricated, and a screwdriver capable of engaging the laboratory screw in the temporary cylinder is positioned (Figure 2). In the matrix, only the coronal part is filled with composite (Triad, Dentsply International, York, Penn.) after which it is placed on the cast. This assembly is positioned in a light-curing oven (Triad 2000, Dentsply International) for two minutes (Figure 3). After removal from the cast, the cylinder is connected to a laboratory fixture analog, and the cementoenamel junction is identified. At this moment, one can appreciate the volume needed to create the underlying "root form." Additional composite is placed to ensure a gradual transition from the fixture level to the tooth structure. Adequate support is needed for the tissue but it should not infringe on the minimal volume needed to maintain blood flow and healthy tissue. A surface sealing composite (Palaseal, Heraeus Kulzer, Inc., Irvine, Calif.) is placed to ensure a smooth, tissue-friendly surface.

	Figure 2. The clear matrix is perforated by the screwdriver for the laboratory implant screw.
	Figure 3. The coronal part is cured. Note the incisal exit of screw access hole, indicating ideal implant angulation for a cement-on prosthesis.

4. The cementoenamel junction is identified and marked with pencil (Figure 4). The coronal part is now prepared with a diamond as if a standard crown preparation (Figure 5). The custom abutment is repositioned onto the cast, and a provisional crown is made to fit. The assembly is now ready for introduction into the oral environment.

	Figure 4. The emergence profile of the abutment has been developed, guided by the fixture position and the cementoenamel junction of the tooth.
	Figure 5. Conventional crown preparation finalized the laboratory phase of the provisional abutment. The provisional coronal restoration is fabricated concurrently.

5. Intraoral access to the fixture is established, and the provisional abutment is fitted (Figure 6). The contours should be modified as needed. The composite has adequate hardness so it is easily shaped with rotary diamonds or added to with light-cured composite material. The provisional coronal restoration is placed with a non-eugenol temporary cement.

6. Over the course of the following eight to 20 weeks, the site is re-evaluated and the abutment adjusted as needed to create adequate pressure for the papilla to form and the proper emergence profile to develop (Figure 7). Once the final tissue contour and consequential abutment form has been established, this information is transferred to the dental laboratory.

 

	Figure 6. Stage II surgery. Connection of the provisional abutment, with a papilla-sparing incision.
	Figure 7. Eight weeks post stage II

Indirect Transfer

With the indirect transfer technique, fixture level impression copings are modified to mirror the gingival component of the provisional abutment. Fixture position and tissue contour are transferred simultaneously to the laboratory model.

1. The provisional abutment is removed from the fixture. At this time, the soft tissue is intimately adapted to the smooth composite surface, suggesting hemi-desmosomal attachment.

2. The abutment is transferred to a jig with a laboratory fixture analog (Figure 8). Clear polyvinyl siloxane (Memosil, Miles Inc., South Bend, Ind.), is injected around the subgingival part of the provisional abutment (Figure 9). Upon setting, the abutment is removed and replaced with a surface-treated fixture level impression coping. The Silicoated surface treatment will ensure a bond between the metal of the coping and the composite additive material.

	Figure 8. The accepted provisional abutment on the transfer jig, fixture analog. The provisional coronal restoration has been placed for illustrative purpose.
	Figure 9. Clear polyvinyl-siloxane has be captured the subgingival part of the abutment.

3. Resin bonding material is applied to the Silicoated surface and a flowable composite (Revolution, Kerr Corp., Orange, Calif.) is carefully introduced between the coping and clear matrix. This assembly is light-cured in a light-curing oven for two minutes. After full polymerization, the impression coping is removed and a surface sealer applied (Palaseal, Heraeus Kulzer, Inc., Irvine, Calif.) to ensure a smooth subgingival surface (Figure 10).

Figure 10. The customized impression coping. Note the exact replication of abutment contours.

4. The modified impression coping is placed intraorally onto the fixture (Figure 11 and 12). At this time, some blanching may occur since the peri-implant soft-tissue may have collapsed without the support from the provisional abutment. A radiograph is made to ensure correct seating onto the fixture (Figure 13). A polyvinyl siloxane impression material (Monophase, G.C. America, Alsip, Ill.) is utilized with a standard open tray. After setting, the impression is removed, leaving the pick-up impression coping embedded in the impression (Figure 14).

	Figure 11. Customized impression coping seated.
	Figure 12. Birdseye view. Note the distinct circumferential shape.
	Figure 13. Radiographic verification of positive seat of customized impression coping.
	Figure 14. The embedded coping, showing the subgingival.

5. A soft tissue and die stone cast is fabricated in the usual manner, replicating the exact fixture position and peri-implant soft-tissue contours.

6. The final abutment and crown are fabricated (Figure 15).

Figure 15. The custom abutment, with porcelain-fused-to-metal restoration.

Direct Transfer

With direct transfer, the actual provisional abutments are utilized to transfer the peri-implant soft-tissue contours and the position of the fixture. As with any transfer technique, care must be exercised because discrepancies can be introduced during each step.

1. The access sleeve to the screw of the provisional abutment (Figure 16) is cleaned. Piece(s) of metal wire 1.5 cm long are coated with a polyether adhesive and set aside. A polyether impression material (Permadyne, ESPE, Seefeld, Germany) is mixed and introduced with a needle tube syringe (Centrix Inc., Shelton, Conn.) into the access sleeve (Figure 17). The metal wire is introduced as a reinforcement into the impression material in the sleeve (Figure 18). The remainder of the impression material is carefully syringed around the abutments and natural teeth (Figure 19), and the filled impression tray is seated.

	Figure 16. Frontal view of provisional abutments. Multiple grafting procedures have preceded this stage after patient endured grave facial trauma.
	Figure 17. Lingual view of provisional abutments, with access channels still obturated.
	Figure 18. Access channels have been filled with reinforced polyether impression material and material is syringed around the external part of the provisional abutments.
	Figure 19. Internal aspect of provisional abutment impression, depicting shape of coronal part of provisional abutments.

2. Upon setting of the polyether impression material, the tray is removed and the impression inspected. After approval, the imprints of the screw head are removed with a round bur to ensure complete seating of the abutment during the next phase.

3. The provisional abutment is then removed from the oral fixture (Figures 20 and 21), and a laboratory fixture analog is attached to it (Figure 22). This assembly is carefully repositioned in the corresponding part of the polyether impression (Figure 23). With the pin of the sleeve and the distinct form of the preparation, this assembly can be adequately secured.

	Figure 20. Frontal view after removal of provisional abutments. Even without support, the appearance of normal gingival contour and papillae is evident.
	Figure 21. Close-up of customized provisional abutment. This distinct shape would be difficult to match with off-the-shelf products.
	Figure 22. Laboratory fixture analogs are connected to the provisional abutments, and the assembly is repositioned into the impression. Polyvinyl-siloxane model material is injected into this impression.
	Figure 23. Occlusal view of the custom abutments in the newly acquired model.

4. A dedicated polyvinyl siloxane material (Model in a Minute, Roydent, Rochester Hills, Mich.) is injected into the impression, followed by the heavy body base material. Because two chemically different materials are used, no bonding will occur, and the cast may be removed from the impression one minute after application of the material. This type of cast is rigid enough for manipulation but has the flexibility of a soft-tissue cast. The fast set allows the clinician to reposition the provisional abutments in a timely manner, which is important because the soft tissue will have a tendency to collapse.

5. The laboratory screws of the provisional abutments are loosened and the abutments removed from the cast (Figure 24). The cast is a replication of the fixture position and the peri-implant soft tissue (Figure 25) and is ready for fabrication of the mirrored final abutments and crowns. The provisional abutments are repositioned intraorally, and the provisional crowns recemented (Figure 26).

	Figure 24. Provisional abutments removed. Note position of fixture heads in relation to contour of abutments.
	Figure 25. The intraorally created soft-tissue contours are exactly duplicated to the cast.
	Figure 26. Final restoration upon cementation.

Conclusion (Summary)

A combination technique is described to fabricate provisional healing abutments and transfer the individualized peri-implant soft-tissue contours to the dental laboratory. This technique will allow the practitioner to deliver highly customized implant care, while utilizing familiar techniques and readily available materials.

Authors

Lambert J. Stumpel, III, DDS, is a director of implant prosthetics at the Alameda Medical Center Oral and Maxillofacial Surgery Residency Program. He is also an assistant clinical professor at the University of California San Francisco School of Dentistry. He maintains a private practice in San Francisco.

Walter Haechler, MDT, is a master dental technician in Corte Madera, Calif.

Edmond Bedrossian, DDS, is the director of the implant program at the Alameda Medical Center Oral and Maxillofacial Surgery Residency Program. He is also an assistant clinical professor at the UCSF School of Dentistry. He maintains a private practice in San Francisco.

References

1. Branemark P-I, Zarb GA, Albrektsson T, Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Quintessence, Chicago, 1985.

2. Daftary F, Dentoalveolar morphology: evaluation of natural root form versus cylindrical implant fixtures. Pract Periodontics Aesthet Dent 9(4):469-77, 1997.

3. Chee W, Donovan T, Use of provisional restorations to enhance soft-tissue contours for implant restorations. Compend Contin Educ Dent 19(5):481-9, 1998.

4. Potashnick S, Soft tissue modeling for the esthetic single-tooth implant restoration. J Esthet Dent 10(3):121-31, 1998.

5. Pissis P, Emergence profile considerations of implant abutments. Pract Periodontics Aesthet Dent 6(7):69-76, 1994.

6. Biggs W, Placement of a custom implant provisional restoration at the second-stage surgery for improved gingival management; a clinical report. J Prosthet Dent 75(3):231-3, 1996.

7. Bichacho N, Landsberg C, Single implant restorations: prosthetically induced soft tissue topography. Pract Periodontics Aesthet Dent 9(7):745-52, 1997.

8. Touati B, Custom-guided tissue healing for improved aesthetics in implant-supported restorations. Int J Dent Symp 3(1):36-9, 1995.

9. Stein J, Nevins M, The relationship of the guided gingival frame to the provisional crown for a single-implant restoration. Compend Contin Educ Dent 17(12):1175-82, 1996.

10. Chee WL, Cho GC, Ha S, Replicating soft tissue contours on working casts for implant restorations. J Prosthod 6:218-220, 1997.

11. Hocwald DA, Surgical template impression during stage I surgery for fabrication of a provisional restoration to be placed at stage II surgery. J Prosthet Dent 6:796-8, 1991.

12. Laufer B-Z, Nicholls JI, Townsend JD, SiOx-C coating: a composite-to-metal bonding mechanism. J Prosthet Dent 60:320-7, 1988.

13. Caeg C, Leinfelder KF, et al, Effectiveness of a method used in bonding resins to metal. J Prosthet Dent 64:37-41, 1990.

To request a printed copy of this article, please contact/Lambert J. Stumpel, III, DDS, 450 Sutter St., Suite 2314, San Francisco, CA 94108.