single implant restorations:

The achievement of an aestheticimplant-supported restorationis a constant challenge to therestorative dentist. Due to thecircular shape of the implant

and its smaller diameter, when comparedto the root of a natural tooth, a dilemmainevitably occurs of how to construct anartificial crown and abutment systemwhich will imitate the natural tooth crownform when emerging from the gingivawith narrow margins to fit the implanthead. In natural teeth, the emergenceprofile angle is relatively straight.1-3 Anyattempt to reproduce this angle in animplant-supported crown will result in arestoration that appears unnatural andartificial, unless it is a lateral maxillaryincisor with root dimensions matchingthe standard dental implants.

THE INTERNATIONAL AESTHETIC CHRONICLE PP&A 745

Figure 1. Case 1. Immediate implant placement (Steri-Oss Ø3.25 mm) into the extractionsocket of the left lateral incisor. Note the extensive buccal plate resorption.

Figure 2. Stage II surgery. Flap is displaced buccally to provide excess soft tissue in buccaland coronal directions. Note no vertical incisions to minimize gingival recession.

Single Implant Restorations:Prosthetically InducedSoft Tissue TopographyNitzan Bichacho, DMDCobi J. Landsberg, DMD

Nitzan Bichacho, DMD, is Vice President

of the European Academy of Esthetic

Dentistry. He is a general dentist main-

taining a private practice limited to

Prosthodontics, Tel Aviv, Israel.

Cobi J. Landsberg, DMD, is a diplomate

of the American Board of Periodontology.

He maintains a private practice limited to

Periodontics and Implant Surgery, Tel Aviv,

Israel.

Address correspondence to:

Nitzan Bichacho, DMD16 Miriam Hahashmonait St.Tel Aviv, Israel 62665

Tel: 011-972-3-60-54-370Fax: 011-972-3-54-60-415

27

An aesthetic transition from the smaller diameter of the implant to the prosthetic restoration that resembles the size of the

natural tooth has presented an ongoing challenge to the implant restorative dentists. The appearance of the surrounding soft

tissue is of major importance, and various techniques have been developed to guide and optimize its topography. The learning

objective of this article is to present a cervical contouring concept, whereby the soft tissue topography is optimally determined

already in the laboratory phase. Using a custom abutment and provisional crown as components of the transmucosal prosthetic

unit (TPU), the topography is transferred to the vital intraoral tissues, which predictably adapt to the enhanced aesthetic configu-

ration. Clinical cases are presented to demonstrate the sequence of the technique in treating the anterior region of the maxilla.

CLINICAL PROCEDURECase 1A 35-year-old female patient presentedrequiring implant-supported restorationof a maxillary lateral incisor. Despitethe difficult initial condition at the pre-sentation (Figure 1), utilizing the currentaugmentation techniques (Figure 2),4

an aesthetically acceptable result wasachieved (Figures 3 and 4). These tech-niques are of primary importance inpreparing the hard and soft tissue sitesuitable for implant placement, sincethe objective of the surgical steps is toenable a precise implant placement inan optimal site in accordance with pros-thetic and aesthetic demands. However,not all teeth to be replaced are lateralincisors, with the cervical diameter ofthe tooth matching the diameter of thestandard implant. Therefore, the chal-lenge remains of how to connect a largenoncircular crown base to a narrow cylindrical implant, while attemptingto achieve a natural-appearing restoration.

Gingival Recontouring TechniquesTo compensate for the discrepanciesbetween the implant head and the naturalroot diameter, several clinical techniqueshave been proposed for reshaping thegingival profile, provided that a sufficientvolume of soft tissue is present:1. Wide temporary healing abutments5

are used to allow gingival matura-tion around a wider cap. Since thediameters of these abutments arestandardized and available only inlimited sizes, it is not possible toachieve an optimal gingival contourin every clinical circumstance.

2. Gingival electrosurgery is used tocut the desired gingival contour.6

The results are not always pre-dictable, since shrinkage of the freegingiva and gingival recession mayresult.7-9

3. Gingivoplasty has been suggestedwith high-speed diamond burs atthe appointment of the final crowndelivery.10 This rotational curettagemight cause unfavorable recession,especially when thin facial tissueis recontoured.11

4. A two-section porcelain-fused-to-metal (PFM) crown might be fab-ricated in which a ceramometal

746 Vol. 9, No. 7 THE INTERNATIONAL AESTHETIC CHRONICLE

Figure 3. A porcelain-fused-to-noble-alloy crown restoration, 6 months postcementation.

Figure 5. Case 2. Stage II surgery. Excessive keratinized tissue displaced buccally andcoronally, surrounding the healing cap (Steri-Oss Ø3.25 mm).

Figure 4. Radiograph of the transmucosal prosthetic unit (TPU) exhibits the precise fit ofall components (implant/abutment/crown).

intracrevicular substructure is con-nected directly to the implant.12

Its profile guides maturation ofthe periabutment gingiva duringthe healing period.

5. Prosthetically induced gingival alter-ation is the most commonly usedsolution; it has been developed byvarious prosthodontists in differentways. Since all cemented implant-supported crowns require trans-mucosal abutments, this prostheticcomponent has gained attentionin implant prosthodontics in recentyears. Where implant location andplanned crown size permit, utiliza-tion of a prefabricated anatomicabutment is the simplest and mostreadily achieved solution. Theseabutments can be slightly modified,if required, and can even be cutintraorally when already attached.13

Modification of a prefabricated titanium abutment has been sug-gested to allow a proper abutmentdesign.14,15

The use of a prefabricated titaniumabutment, to be modified with gold over-casting to an individual shape, has alsobeen suggested.16 Another alternativeis the use of a custom-made abutmentwith PFM subcervical region.17 Advancedprefabricated anatomical abutments(DIA Anatomic Abutment System, Steri-Oss, Yorba Linda, CA) have been intro-duced,18,19 followed by the Bio-Estheticabutment system.20 The introductionof a tooth-colored ceramic abutment21-23

is not only configuration-oriented, butit also augments the abutment by itsfourth dimension — color. The mostcommon procedure for obtaining thedesired abutment configuration is theuse of modified plastic cylinders in thelost wax technique to produce customizedgold cylinders.24 Prefabricated plasticcylinders are also utilized for the fabri-cation of provisional restorations.25

Cervical Contouring ConceptThe prosthetic components, apical tothe free gingival margins, form theTransmucosal Prosthetic Unit (TPU).The TPU can be composed of severalcombinations:

1. Implant alone – the implant headis located supragingivally.


Figure 6. Cervical contouring concept. Reshaping the circular cross-cut.

Figure 8. The prefabricated acrylic resin provisional crown is seated by exerting gradualpressure on the soft tissue. Note the transient blanching of the soft tissue.

Figure 7. Soft tissue replica redesign. Cross-cut and gingival level correspond to adjacentcentral incisor.

2. Implant head + abutment – the abut-ment shoulder is supragingival.

3. Implant head + crown – the crownis screwed directly to the implant(UCLA type) without an intermediateabutment.

4. Implant head + abutment + crown– the apical part of the crown is sub-gingival and sits on the abutmentthat is screwed to the implant. Thisis the most commonly found com-bination.According to the components

selected, any TPU is a combination ofsome of the following materials: Titanium(implants and some abutments); goldalloys (some abutments and some crowns);nonprecious alloys (some abutments andsome crowns); ceramics (some abutmentsand some crowns); composite resins (somecrowns); acrylic resins (some crowns).

The cervical contouring conceptfurther addresses the achievement ofpredictable results.26 It is logical to con-clude that the most important factorresponsible for a natural appearance ofthe restoration is the desired configu-ration and dimension of its surroundingsoft tissue. Therefore, regardless of thetype of TPU selected, this concept placesemphasis on the design of the soft tissue.The periprosthetic region is envisionedto an optimal configuration and redesignedpreviously in the laboratory phase. Thisideal design is transferred to the vitaloral tissue through the abutment andprovisional restoration which are fabricatedaccordingly, guiding the surroundingsoft tissue to imitate the model replica.The periimplant gingival tissue is dupli-cated by a rigid acrylic resin (Dura-Lay,Reliance, Worth, IL) to allow improvedcontrol of the remodeling process. Carvingthe periabutment gingiva in the workingmodel allows fabrication of the prosthetic


Figure 9. Power brushing is performed to adjust hyperplastic tissue contour.

Figure 11. Three-month postcementation view of the porcelain crown. Note naturalemergence from soft tissue.

Figure 10. Six weeks following provisional crown cementation, using electric toothbrushingtechnique. Note adjustment process of the soft tissue.

This ideal design is transferred to

the vital oral tissue through the

provisional restoration which is

fabricated accordingly ...

components in the desired dimensions,which are placed intraorally, where theperiabutment tissue adjusts itself to theTPU components (abutments, provisionalrestorations, and final restorations).

The cervical contouring conceptfocuses on shaping the abutment andthe cervical crown region following theprior design of the surrounding tissuesand facilitates predictable, proper fab-rication of an implant-supported crown,despite the difficulties created by theshape of the implant fixture (Table).

Case 2A 22-year-old male patient presented with a missing left central incisor. Duringsecond-stage surgery, the flap was trans-ferred buccally to provide sufficientsoft tissue to be reshaped at a later stage(Figure 5). The excess of gingival tissuewas intentional, due to anticipated

recession of the buccal soft tissue follow-ing the connection of the prosthetic com-ponents. In this case, the margins ofthe tissue covering the healing abutmentwere placed approximately 3 mm incisallyfrom their designated final location.

Following impression-taking andpouring the model according to thecervical contouring concept, reshapingof the circular periabutment tissue wasperformed in the laboratory (Figure 6)to provide suitable periabutment dimen-sions for this central incisor. The buccalmargins were carved away apically(approximately 3 mm) to the level ofthe free gingival margin of the contra-lateral tooth. A triangular shape wascreated in cross-cut, which is typicalof a natural central incisor of this level(Figure 7). A provisional acrylic resincrown was fabricated on a transmucosalindividual gold abutment. Its volumefilled the space between the abutmentand the periabutment remodeled replica.


Figure 14. The transmucosal abutments connected intraorally.

Figure 13. Type IV gold alloy is used to fabricate customized abutments according to thecervical contouring concept.

The cervical contouring

concept focuses on shaping

the abutment and the cervical

crown region ...

Figure 12. Case 3. Impression copings screwed to the implants (Steri-Oss Ø3.25 mm).Note favorable implant position and orientation.

Once the abutment was connectedintraorally, the prefabricated provisionalcrown was seated, and digital pressurewas exerted to compress the gingiva(Figure 8). The pressure created a tran-sient blanching of the soft tissue, result-ing in transformation of its dimensionsto the crown configuration. Following6 weeks and a meticulous oral hygieneregimen with an electric plaque remover(Braun Oral-B Electric Plaque Remover,Redwood City, CA) (Figure 9), the tissueadjusted to a more favorable locationand contour (Figure 10). In most similarcases, approximately 6 months are requiredfor the soft tissue to reach a completelynatural appearance within its long-termmaturation period (Figure 11).

Case 3A 47-year-old female patient accepteda treatment plan requiring restorationof the anterior maxilla, involving 3 nat-ural teeth and 2 implant-supported

restorations. Following optimal place-ment of the 2 implants to replace theleft lateral incisor and canine, con-ventional surgical augmentation tech-niques were used, and an impressionof the implant heads was taken (Figure12). Following the desired modificationof the soft tissue replica, two individualtype IV gold abutments (BIO-H; APM-Sterngold, Attleboro, MA) were fabricatedaccording to the cervical contouringconcept (Figure 13) and connected tothe implants intraorally (Figure 14).The natural teeth abutments, adjacentto the customized implant transmucosalabutments, were prepared accordingto conventional crown-and-bridge tech-niques, and final preparation of theimplant abutments was performed intra-orally (Figure 15). Provisional acrylicresin single crowns were adapted chairsideand cemented temporarily for an evalu-ation period of 2 months (Figure 16).


Figure 16. Two months postcementation of provisional acrylic resin crowns.

Figure 15. Final preparation of the implant abutments and the natural teeth.

Table

Cervical Contouring Concept Sequence of Treatment

1. Impression is taken of implant head.2. Resin is poured in the periabutment zone.3. Combined working model is fabricated: Hard stone, periimplant zone, and implant

analog. 4. Periabutment resin is recontoured to ideal dimensions in accordance with adjacent

and contralateral teeth and their free gingival margins.5. Transmucosal abutment is selected (prefabricated or custom fabricated) according to

the new optimal soft tissue configuration.6. Provisional acrylic resin crown is fabricated according to the abutment and Dura-Lay

dimensions and shape. 7. The abutment is transferred and connected to the implant, intraorally.8. The provisional crown is positioned on the abutment with gradual digital pressure.9. The crown is removed and cemented with temporary noneugenol cement.

10. Oral hygiene regimen includes powerbrushing with electric plaque remover.11. An observation and evaluation period lasts at least 8 weeks.12. Routine conventional crown-and-bridge techniques follow.

Intraoral Procedures Laboratory Phase

The periprosthetic region is envi-

sioned to an optimal configuration

and redesigned previously in

the laboratory phase.

The impressions were taken usingthe conventional cord-retraction tech-nique, and a “Geller” model was produced,whereby the soft tissue impression wascast-replicated in hard plaster stone(Figure 17). A small amount of the stonein the buccal and interdental sulci wasremoved, creating a gap between theabutments and the inner aspect of thefree gingiva. This prosthetic adjustmentwas performed to restore the anatomiccurvature in the sulci and allow intra-crevicular convexity of the crown restora-tions.27 Noble composite alloy copings(Captek, Longwood, FL) were fabricatedin the laboratory to elicit a favorableresponse from the adjoining vital tissuesand enhance a natural background forthe veneering materials (Figure 18).28,29

Porcelain (Creation, Jensen, NorthHaven, CT) was baked onto the copingsof the natural teeth due to its natural

opalescent and fluorescent effect increating intensified optical depth andbrilliance of the porcelain restorations.

The implant copings were coveredwith polyglass resin (Artglass, HeraeusKulzer, Irvine, CA) to provide a moreflexible material, since these implant-supported crowns shared in the anteriorguidance and lateral movements in theocclusal pattern of the patient. Althoughasymmetrical, this combination createda harmonized and aesthetic anteriordentition (Figure 19).

CONCLUSIONGreat steps forward are being taken inimplant dentistry. The use of singleimplants has become a legitimate treat-ment option in fulfilling specific reha-bilitation requirements, and the utili-zation of this treatmant option is notlimited to the anterior region.30,31 The


Figure 17. A “Geller” model is produced following a conventional crown-and-bridge impression technique.

Figure 19. Final cementation of the 3 natural teeth with porcelain-fused-to-gold crownsand 2 polyglass-fused-to-gold implant-supported crowns.

Figure 18. Intraoral fit verification of single unit copings.

The use of single implants has

become a legitimate treatment

option in fulfilling specific

rehabilitation requirements ...


REFERENCES1. Croll BM. Emergence profiles in natural tooth contour.

Part I: Photographic observations. J Prosthet Dent 1989;62:4-10.

2. Croll BM. Emergence profiles in natural tooth contour.Part II: Clinical considerations. J Prosthet Dent 1990;63:374-379.

3. Becker CM, Kaldahl WB. Current theories of crown con-tour margin placement and pontic design. J ProsthetDent 1981;45:268.

4. Becker W, Becker BE. Flap designs for minimization ofrecession adjacent to maxillary anterior implant sites: Aclinical study. Int J Oral Maxillofac Impl 1996;11(1):46-54.

5. Lazzara RJ. Managing the soft tissue margin: The key toimplant aesthetics. Pract Periodont Aesthet Dent1993;5(5):81-87.

6. Langer B, Sullivan DY. Osseointegration: Its impact onthe interrelationship of periodontics and restorativedentistry: Part I. Int J Periodont Rest Dent 1989;9:165-183.

7. Azzi R, Kenney EB, Tsao TF, Carranza FA Jr. The effectof electrosurgery on alveolar bone. J Periodontol1983;54:96-100.

8. Azzi R. Electrosurgery in periodontics: A literaturereview. J West Soc Periodontol 1981;29:4.

9. De Vitre R, Galburt RB, Maness WJ. Biometric compari-son of bur and electrosurgical retraction methods.J Prosthet Dent 1985;53:179-182.

10. Holloway JA, McGlumphy EA. Soft tissue contouring foraesthetic single-tooth implant restorations. PractPeriodont Aesthet Dent 1993;5(9):41-48.

11. Kamansky F, Temple T, Post A. Gingival tissue responseto rotary curettage. J Prosthet Dent 1984;52:380-383.

12. Hürzeler MB, Quiñones CR, Strub JR. Advanced surgicaland prosthetic management of the anterior single toothosseointegrated implant: A case presentation. PractPeriodont Aesthet Dent 1994;6(1):13-21.

13. Gross M, Laufer BZ, Ormianar Z. An investigation onheat transfer to the implant-bone interface due to abut-ment preparation with high-speed cutting instruments.Int J Oral Maxillofac Impl 1995;10(2):207-211.

14. Touati B. Custom-guided tissue healing for improvedaesthetics in implant-supported restorations. Int J DentSymp 1995;3:36-39.

15. Saadoun AP, Sullivan DY, Krischek M, Le Gall M. Singletooth implant — Management for success. PractPeriodont Aesthet Dent 1994;6(3):73-80.

16. Rieder C. Customized implant abutment copings toachieve biologic, mechanical and esthetic objectives. IntJ Periodont Rest Dent 1996;16(1):21-29.

17. Misch C. The maxillary anterior single-tooth implantaesthetic-health compromise. Int J Dent Symp 1995;3:4-9.

18. Daftary F, Bahat O. Prosthetically formulated naturalaesthetics in implant prostheses. Pract PeriodontAesthet Dent 1994;6(9):75-83.

19. Daftary F. Natural esthetics with implant prostheses.J Esthet Dent 1995;7(1):9-17.

20. Daftary F. The Bio-Esthetic abutment system: An evolu-tion in implant prosthetics. Int J Dent Symp 1995;3:10-15.

21. Prestipino V, Ingber A. Esthetic high-strength implantabutments: Part I. J Esthet Dent 1993;5(1):29-35.

22. Prestipino V, Ingber A. Esthetic high-strength implantabutments: Part II. J Esthet Dent 1993;5(2):63-68.

23. Prestipino V, Ingber A. All-ceramic implant abutments:Esthetic indications. J Esthet Dent 1996;8(6):255-262.

24. Tarnow DP, Eskow RN. Preservation of implant esthetics:Soft tissue and restorative considerations. J Esthet Dent1996;8(1):12-19.

25. Lewis S, Parel S, Faulkner R.. Provisional implant-supported fixed restorations. Int J Oral Maxillofac Impl1995;10(3):319-325.

26. Bichacho N, Landsberg CJ. A modified surgical/pros-thetic approach for an optimal single implant-supportedcrown. Part II — The cervical contouring concept. PractPeriodont Aesthet Dent 1994;6(4):35-41.

27. Bichacho N. Cervical contouring concepts: Enhancingthe dentogingival complex. Pract Periodont AesthetDent 1996;8(3):241-254.

28. Zappala C, Bichacho N, Prosper L. Options in aestheticrestorations: Discoloration and malformation, problems andsolutions. Pract Periodont Aesthet Dent 1994;6(8):43-52.

29. Binderman I. Bone and biologically compatible materi-als in dentistry. Curr Opin Dent 1991;1:836-840.

30. Henry PH, Laney WR, Jemt T, et al. Osseointegratedimplants for single-tooth replacement: A prospective5-year multicenter study. Int J Oral Maxillofac Impl1996;11(4):450-455.

31. Avivi-Arber L, Zarb GA. Clinical effectiveness of implant-supported single-tooth replacement: The Toronto study.Int J Oral Maxillofac Impl 1996;11(3):311-321.

aesthetic demands of this treatmentmodality, limited by the characteristicsof the implant systems available, dictatecertain modifications of the traditionalrecommended treatment options forconventional prosthetic implant den-tistry. However, the various prostheticsolutions represent uncertain long-term results: The current TPU compo-nents and techniques have been devel-oped to compensate for the differencesbetween the implant configuration andthe respective crowns. This dictatesplacement of the implant head deepunder the free gingival margin, especiallyin the anterior region of the maxilla,so that the TPU has a sufficient distanceto be transferred from a circular andnarrow region (connected to the implant)to a crown-form region (supportingthe crown).

The present implant restorativesystems potentiate the development ofdeep pockets, particularly in the inter-proximal areas from the peak of thepapillae to the implant head. This maylead to abscess formation, periimplantitis,and eventual implant failure. Even in anoninflammatory state, the periprostheticsoft tissues remain insufficiently sup-ported; this compromised biophysicalcondition predisposes to recession andloss of interdental papillary height withintime. No other perioprosthetic treatmentmodalities of such nature would be con-sidered adequate and predictably suc-cessful on a long-term basis. A reasonablesolution for enhancing the periimplantrestoration environment is probablyby conversion of the traditional circularcross-cut of the implant head to thatof a natural root. When this modificationis then performed at the level of theimplant head instead of the abutment,it will be possible to place the implanthead considerably closer to the soft tissuemargins surrounding the crown, therebycreating not only an aesthetic and func-tional restoration but also fulfilling thebiologic criteria for a long-term service.

AcknowledgmentsThe authors would like to thank R. Lahav,

CDT, and S. Silberstein, CDT, both of Tel

Aviv, Israel, for the ceramic restorations

presented in this article.

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1. The dimensions of which tooth are closest to thoseof an implant in the cervical area?a. Maxillary central incisor.b. Maxillary lateral incisor.c. Mandibular molar.d. Maxillary canine.

2. The clinical techniques proposed to modify the softtissue surrounding dental implants include:a. Wide temporary healing abutments.b. Electrosurgery.c. Gingivoplasty.d. All of the above.

3. A TPU may create combinations of:a. Implant + crown, incisal half.b. Implant + crown, incisal third.c. Implant + abutment + crown, cervical third.d. Provisional crown + permanent crown.

4. The cervical contouring concept places first emphasis on:a. Diameter of the implant.b. Diameter of the abutment.c. Design of the soft tissue.d. None of the above.

5. The design for contouring is transferred from laboratory to the vital tissue by:a. Cast plaster model for duplication.b. Specific written instructions.c. Provisional restoration and a custom abutment.d. None of the above.

6. During the second-stage surgery, the flap createsintentional: a. Excess gingival tissue, to be reshaped subsequently.b. Insufficient tissue.c. Adequate tissue.d. None of the above.

7. One type of TPU placed in Case 2 was:a. Acrylic resin on titanium abutment.b. Acrylic resin on gold abutment.c. Gold alloy on titanium abutment.d. Silver alloy on ceramic abutment.

8. In the majority of cases, the time required for thetissue to reach a completely natural appearance isapproximately:a. 6 weeks.b. 16 weeks.c. 6 months.d. 16 months.

9. Intraoral preparation of adjacent teeth as abutmentswas: a. Not allowed.b. Completed according to the conventional crown-

and-bridge technique.c. Performed as for full-coverage all-ceramic crowns.d. None of the above.

10. To reduce the subgingival soft tissue pocket, theauthors suggest conversion of the traditionalcircular cross-cut of the implant head to that ofa natural root.a. True.b. False.

To submit your CE Exercise answers, please use the enclosed Answer Card (one for all 5 CE articles) foundopposite page 792, and complete it as follows: 1) Complete the address; 2) Identify the Article/Exercise Number;3) Place an X in the appropriate answer box for each question for each exercise. Return the completed card.The 10 multiple-choice questions for this Continuing Education (CE) exercise are based on the article “Singleimplant restorations: Prosthetically induced soft tissue topography” by Nitzan Bichacho, DMD, and Cobi J.Landsberg, DMD. This article is on Pages 745-752. Answers for this exercise will be published in the November/December 1997 issue of PP&A.

Learning Objectives:This paper presents a cervical contouring concept, whereby the soft tissue topography is optimally determined already in the labora-tory phase. Upon reading and completion of this CE exercise, the reader will acquire:• Familiarity with the principles of cervical contouring.• Knowledge to clinically implement the concept.

Continuing Education (CE) Exercise No. 27

sm

UTHSCSA

27


single implant restorations:

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