Restoring the Partially Edentulous Patient in the Aesthetic Zone Using Implants and All-Ceramic Restorations: Case Report

Aesthetics is a critical factor in regard to patient satisfaction with the outcome of treatment. Metal-free restorations provide an aesthetic result while offering excellent biocompatibility and strength.1-3 While a conventional metal-ceramic restoration may be functionally acceptable, the metal substructure may result in a change of color at the free gingival margin due to the translucency of the gingival tissues.4 Further, the substructure is associated with a lack of translucency of the overall restoration due to the opacity of the material, resulting in a less than lifelike restoration.5,6
A relatively new treatment modality is the all-ceramic restoration, including crowns and fixed partial dentures, which was introduced in 1967.7 With the increasing emphasis on aesthetics, several new all-ceramic systems for fixed partial denture restorations have been introduced.8,9 These all-ceramic restorations include Procera (Nobel Biocare), IPS Empress 2 (Ivoclar Vivadent), and In-Ceram (VITA Zahnfabrik).
The options for restoring an edentulous area have changed dramatically in the last 20 years, due in large part to the introduction of endosseous dental implants. Since the pioneering work by Branemark,10 the use of osseointegrated implants to replace missing teeth has become the treatment of choice for many patients. Implants may vary in shape, length, width, and surface coating, yet the major available systems all report a success rate of 95% over 5 to 10 years.11-14
The conventional implant placement protocol developed by Branemark and colleagues15 involves a 3-month to 6-month healing period for a submerged implant. For implants placed immediately into extraction sites, the protocol calls for a healing period of 8 to 12 weeks. With careful case selection, immediate placement of implants in extraction sites can reduce the time until the final restoration.16,17
Implant abutments that are computer designed and manufactured have also changed the restorative protocols for implant dentistry. With the 3-dimensional computer-aided design (3-D CAD) technique, the clinician is able to design custom abutments and crowns, and fabricate them using all-ceramic materials that will improve the final aesthetic outcome. Customized abutments from several different materials may be fabricated with the 3-D CAD technique. This enables the practitioner to fabricate individualized implant components with the desired height and width to meet alignment necessities and size discrepancies, and to support the adjacent tissue that is usually compromised due to the loss of gingival papillae height as well as changes in the thickness of the overlying gingiva. The individualized implant components  allow the restoration to mimic the natural dentition.18-20
This report describes the rationale and prosthodontic treatment of a partially edentulous patient who presented with a metal-ceramic 3-unit fixed partial denture, missing the maxillary right central incisor. In addition, external root resorption was present on the maxillary right lateral incisor. The maxillary right central incisor had been removed 8 years before due to external root resorption. The new prosthodontic treatment plan included extraction of the maxillary right lateral incisor with immediate implant placement, as well as implant placement in the area of the maxillary right central incisor. All-ceramic single restorations were to be used to restore both implants as well as the maxillary left central incisor.

CLINICAL REPORT

Figure 1. Three-unit fixed partial denture.	Figure 2. External root resorption (location noted by “A”).

A 24-year-old male reported to the University of Michigan School of Dentistry Department of Prosthodontics with a chief complaint of discomfort in the area of the right lateral and central incisor. The patient presented with a 3-unit fixed partial denture (Figure 1) extending from the maxillary left central incisor to the maxillary right lateral incisor, with the maxillary right central incisor as a pontic. The radiographic examination indicated that the maxillary right lateral incisor presented with external root resorption (Figure 2).
Several treatment options were presented to the patient: (1) extraction of the maxillary right lateral incisor and placement of a 5-unit bridge from the maxillary right canine to the left lateral incisor; (2) extraction of the maxillary right lateral incisor and placement of a removable partial denture to replace the missing teeth, with a single crown on the left central incisor; (3) removal of the 3-unit fixed partial denture, extraction of the maxillary right lateral incisor, and placement of an immediate implant in the extraction site and an implant in the existing edentulous site of the right central incisor. The implants would be restored with custom abutments and all-ceramic restorations, and the left central incisor would be restored with an all-ceramic crown. The decision was made to proceed with the third treatment option.
The treating dentist performed a complete dental examination as well as a review of the medical history, and no findings contraindicated dental care, including implant surgery.

Treatment

The surgical phase of treatment consisted of the following procedures:

Figure 3. Radiograph of implant placement.	Figure 4. Permucosal healing abutments, at the time of the second-stage surgery.
Figure 5. Ceramic abutments (A); facial concavity (B).	Figure 6. Provisional restorations.
Figure 7. Final restorations.	Figure 8. Final restorations. Patient demonstrating a low smile line.

• Sectioning of the 3-unit fixed partial denture, leaving the crown on the left central incisor to serve as a provisional restoration.
• Elevation of a full-thickness mucoperiosteal flap.
• Using a surgical guide for correct positioning of the implants, placement of an external hexagon implant (Branemark [Nobel Biocare]; 13-mm length, 4.0-mm width) in the area of the right central incisor. Also, extraction of the right lateral incisor and immediate placement of an external hexagon implant (Branemark; 15-mm length, 4.0-mm width). The implants are shown in Figure 3.
• Approximation of the full-thickness mucoperiosteal flaps and closing of the margins with 3-0 synthetic absorbable sutures (Vicryl [Johnson & Johnson]) to permit healing by primary intention.
  Following the procedures described above, the patient was given a clear retainer made with a suck-down material (Biocryl [Great Lakes Orthodontics]) with resin acrylic teeth embedded to serve as a provisional restoration. After 4 months a second-stage surgery was performed, including a semilunar incision in the area of the implants and placement of 2 permucosal healing abutments that were 3 mm in height (Figure 4).
  The restorative phase of treatment consisted of the following:
• After soft-tissue healing for a period of 5 weeks,21 closed-tray impression copings were placed and verified radiographically for fit.
• The left central incisor was circumferentially prepared with a moderate chamfer margin; the decision was made to leave the finish line supragingival due to the presence of a facial concavity that extended well below the gingival margin (Figure 5). Retraction cord “00” (Ultradent Products) impregnated with hemostatic solution (Hemodent [Premier Dental Products]) was placed for gingival retraction.
• An implant-level impression was performed to relate the soft-tissue contours as well as the position of the implant platform to the other teeth. This technique consists of connecting the impression coping to the implant and utilizing a closed-tray impression technique with vinyl polysiloxane impression material (light body and heavy body). During this impression process the left central incisor was also included.
• The information from the implant platform was transferred via the impression coping, which was connected to an implant replica and placed into the impression.
• The impression was poured using a soft-tissue moulage with elastic, pink-colored vinyl polysiloxane (Ivoclar Vivadent) and type V gypsum material (Die-Keen [Heraeus Kulzer]).
• A second pour of the impression was made utilizing the same materials. With the second cast, provisional implant abutments were placed and used to fabricate a temporary fixed partial denture with acrylic resin (Lang Dental Manufacturing; Figure 6).
• With the first poured cast, 2 custom zirconium abutments were fabricated using a 3-D CAD program (Procera  [Nobel Biocare]). The tooth preparation and abutments were then digitized using the touch probe scanner (Procera Piccolo [Nobel Biocare]), and copings were fabricated in zirconia (Procera). Zirconia was the material of choice because of its flexural strength22 and resistance to fracture.23 The veneering porcelain (Nobel-Rondo [Nobel Biocare]) was applied to complete the aesthetic portion of the crowns.
• At the delivery appointment the temporary abutments were removed and the ceramic custom abutments were placed and secured using 35 Ncm torque. The access opening was filled with cotton, and the all-ceramic crowns were placed onto the abutments to verify marginal integrity, occlusal relationship, and aesthetic result. The all-ceramic restorations were cemented to the implant abutments using provisional cement marketed for use with dental implant restorations (Premier Implant Cement [Premier Dental Products]).
• The single crown on the left central incisor was placed onto the tooth abutment and evaluated for marginal integrity, occlusal relationship, and aesthetics. The margins of the fixed partial denture were all supragingival, which facilitated visual and tactile assessment of marginal integrity.
• The tooth was cleaned with pumice (Whip Mix) and treated with chlorhexidine (Zila Pharmaceuticals), and the internal surface of the crown was cleansed with alcohol. A thin coat of resin-modified glass ionomer cement (FujiCem [GC  America]) was placed into the internal surface of the all-ceramic crown, and the restorations were delivered with finger pressure.

In summary, the treatment consisted of replacing the right central incisor and the right lateral incisor with implants, custom-designed zir-conium abutments, and all-ceramic restorations. The left central incisor was restored with an all-ceramic crown (Figures 7 and 8).
The patient was recalled at 1 week and at 1 month; no occlusal adjustment was needed after the cementation appointment.

DISCUSSION

Reports have examined the longevity of implants placed in extraction sockets (immediate implants) compared to implants placed in healed alveolar sites. Tsai24 reported that after a period of 5 to 7 years of function, bone level changes between the 2 groups were not statistically significant, which suggests that by careful selection of patients either approach may be used with comparable results.
Accompanying the increased use of dental implants, new restorative materials have been introduced to the dental profession. Materials such as zirconium oxide and aluminum oxide have been developed. These materials are becoming the material of choice for many practitioners due to their excellent aesthetic properties as well as their outstanding physical characteristics and biocompatibility.25
Treatment planning options for adult patients often involve restoring an edentulous area. Frequently, the decision is between a conventional fixed partial denture supported by natural teeth, versus individual crown restorations on implants. Success rates and expected longevity of the restorations are of primary interest for both clinicians and patients. In a study by Romeo,14 cumulative implant survival rates were calculated for implants supporting single-tooth prostheses. There was a failure rate of 4.4% after 7 years. Studies on the longevity of fixed partial dentures involving natural tooth abutments have found that the main reason for failure is caries.26,27 Longevity of fixed partial dentures on natural teeth is determined by the time in service. De Backer determined that the failure rate was 33.8% after 20 years.28
Based on favorable outcomes for single-tooth,  implant-supported prostheses compared to fixed partial dentures with natural teeth as abutments, many clinicians choose implant-supported prostheses. With this approach to tooth replacement, concerns include the type of restoration (screw- retained, cement-retained) and type of cementation (permanent, temporary).
Several authors have suggested that the advantages of cement-retained implant restorations include passivity of fit, improved direction of load, enhanced aesthetics, im-proved access, reduced crestal bone loss, progressive loading, minimum complications, and savings in cost and time.29,30 However, Misch³¹ has noted limitations of cement-retained restorations, including limited interarch space, limited retrievability, and unintended remaining cement in the sulcus. The use of cements with implant-retained restorations (provisional and permanent) is an important topic. Currently, permanent cements generally are not recommended for implant crown retention due to limitations in retrieving the restorations. The use of provisional cements has been suggested when implant-retained restorations are used.30-32

CONCLUSION

In this report the maxillary right central incisor and the right lateral incisor were replaced with implants (including one immediate implant) and restored with metal-free ceramic restorations. The placement of endosseous implants in edentulous areas has proven to be an excellent option for replacing single or multiple teeth, and the use of ceramic abutments and all-ceramic crowns helps the clinician attain long-term success and excellent aesthetic results.

References

1. Narcisi EM. Three-unit bridge construction in anterior single-pontic areas using a metal-free restorative. Compend Contin Educ Dent. 1999;20:109-120.
2. Segal BS. Retrospective assessment of 546 all-ceramic anterior and posterior crowns in a general practice. J Prosthet Dent. 2001;85:544-550.
3. Potiket N, Chiche G, Finger IM. In vitro fracture strength of teeth restored with different all-ceramic crown systems. J Prosthet Dent. 2004;92:491-495.
4. Blatz MB. Long-term clinical success of all-ceramic posterior restorations. Quintessence Int. 2002;33:414-426.
5. Jacobs SH, Goodacre CJ, Moore BK, et al. Effect of porcelain thickness and type of metal-ceramic alloy on color. J Prosthet Dent. 1987;57:138-145.
6. Terada Y, Maeyama S, Hirayasu R, et al. The influence of different thicknesses of dentin porcelain on the color reflected from thin opaque porcelain fused to metal. Int J Prosthodont. 1989;2:352-356.
7. McLean JW. High-alumina ceramics for bridge pontic construction. Br Dent J. 1967;123:571-577.
8. Luthy H, Filser F, Loeffel O, et al. Strength and reliability of four-unit all-ceramic posterior bridges. Dent Mater. 2005;21:930-937.
9. Sundh A, Molin M, Sjogren G. Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing. Dent Mater. 2005;21:476-482.
   
10. Branemark P-I. Introduction to osseointegration. In: Branemark P-I, Zarb GA, Albrektsson T (eds). Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry. Chicago, Ill: Quintessence; 1985:11-17.
11. Wennstrom JL, Ekestubbe A, Grondahl K, et al. Implant-supported single-tooth restorations: a 5-year prospective study. J Clin Periodontol. 2005;32:567-574.
12. Gotfredsen K. A 5-year prospective study of single-tooth replacements supported by the Astra Tech implant: a pilot study. Clin Implant Dent Relat Res. 2004;6:1-8.
13. O’Brien GR, Gonshor A, Balfour A. A 6-year prospective study of 620 stress-diversion surface (SDS) dental implants. J Oral Implantol. 2004;30:350-357.
14. Romeo E, Lops D, Margutti E, et al. Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system. Int J Oral Maxillofac Implants. 2004;19:247-259.
15. Branemark PI, Hansson BO, Adell R, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl. 1977;16:1-132.
16. Becker W, Sennerby L, Bedrossian E, et al. Implant stability measurements for implants placed at the time of extraction: a cohort, prospective clinical trial. J Periodontol. 2005;76:391-397.
17. Chen ST, Wilson TG Jr, Hammerle CH. Immediate or early placement of implants following tooth extraction: review of biologic basis, clinical procedures, and outcomes. Int J Oral Maxillofac Implants. 2004;19(suppl):12-25.
18. Sadoun M, Perelmuter S. Alumina-zirconia machinable abutments for implant-supported single-tooth anterior crowns. Pract Periodontics Aesthet Dent. 1997;9:1047-1053.
19. Boudrias P, Shoghikian E, Morin E, et al. Esthetic option for the implant-supported single-tooth restoration: treatment sequence with a ceramic abutment. J Can Dent Assoc. 2001;67:508-514.
    
20. McLaren EA, White SN. Glass-infiltrated zirconia/alumina-based ceramic for crowns and fixed partial dentures. Pract Periodontics Aesthet Dent. 1999;11:985-994.
21. Misch C. Contemporary Implant Dentistry. 2nd ed. St Louis: Mosby; 1999:89-118.
22. White SN, Miklus VG, McLaren EA, et al. Flexural strength of a layered zirconia and porcelain dental all-ceramic system. J Prosthet Dent. 2005;94:125-131.
23. Guazzato M, Albakry M, Ringer SP, et al. Strength, fracture toughness and microstructure of a selection of all-ceramic materials. Part II. Zirconia-based dental ceramics. Dent Mater. 2004;20:449-456.
24. Tsai ES, Crohin CC, Weber HP. A five-year evaluation of implants placed in extraction sockets. J West Soc Periodontol Periodontal Abstr. 2000;48:37-47.
25. Prestipino V, Ingber A. All-ceramic implant abutments: esthetic indications. J Esthet Dent. 1996;8:255-262.
26. Schwartz NL, Whitsett LD, Berry TG, et al. Unserviceable crowns and fixed partial dentures: life-span and causes for loss of serviceability. J Am Dent Assoc. 1970;81:1395-1401.
27. Walton JN, Gardner FM, Agar JR, et al. A survey of crown and fixed partial denture failures: length of service and reasons for replacement. J Prosthet Dent. 1986;56:416-421.
28. De Backer H, Van Maele G, De Moor N, et al. A 20-year retrospective survival study of fixed partial dentures. Int J Prosthodont. 2006;19:143-153.
29. Misch CE. Principles for cement-retained fixed implant prosthodontics. In: Contemporary Implant Dentistry. St Louis, Mo: Mosby; 1993:651-658.
    
30. Hebel KS, Gajjar RC. Cement-retained versus screw-retained implant restorations: achieving optimal occlusion and esthetics in implant dentistry. J Prosthet Dent. 1997;77:28-35.
31. Misch CE. Screw-retained versus cement-retained implant-supported prostheses. Pract Periodontics Aesthet Dent. 1995;7:15-18.
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Dr. Abbo is a Clinical Lecturer of dentistry, Biologic and Materials Sciences, Division of Prosthodontics, University of Michigan School of Dentistry. He can be reached at (734) 904-9809 or abbovan@umich.edu.

Dr. Razzoog is Professor of Dentistry, Biologic and Materials Sciences, Division of Prosthodontics, University of Michigan School of Dentistry. He can be reached at merim@umich.edu.

Continuing Education Test No. 84.1

After reading this article, the individual will learn:

• a clinical technique for restoring a partially edentulous patient with implant-supported restorations in the aesthetic zone, and
• the longevity of single implant-supported restorations compared to fixed partial dentures involving natural tooth abutments.

1. Success rates for implants over a period of 5 to 10 years is ____.

a. 100%
b. 99%
c. 95%
d. 87%

2. Which of the following is NOT an all-ceramic system?

a. Procera
b. Lava
c. IPS Empress 2
d. none of the above

3. The Branemark implant placement protocol involves a period of healing of ____.

a. 1 to 3 months
b. 3 to 6 months
c. 6 to 8 months
d. none of the above

4. When taking an impression for implants, the first step after disinfecting the impression should be ____.

a. pour the impression with stone
b. use soft-tissue moulage
c. place the implant replica and the impression coping into the impression
d. none of the above

5. According to De Backer, the 20-year survival rate for fixed partial dentures is ___.

a. 66.2%
b. 90%
c. 33.8%
d. 80%

6. Metal-ceramic restorations are associated with ____.

a. lack of translucency
b. lack of strength
c. increased opacity
d. a and c

7. The healing period for implants placed in extraction sites is ____.

a. 8 to 12 months
b. 3 to 6 months
c. 8 to 12 weeks
d. 6 to 8 weeks

8. Advantages of cement-retained implant-supported restorations include ____.

a. passivity of fit
b. improved direction of load
c. enhanced aesthetics
d. all of the above

To submit Continuing Education answers, download the answer sheet in PDF format (click Download Now button below). Print the answer sheet, identify the article (this one is Test 84.1), place an X in the box corresponding to the answer you believe is correct, and mail to Dentistry Today Department of Continuing Education (complete address is on the answer sheet).