Integrating Various Ceramic Materials and Adhesive Concepts to Achieve a Functional and Esthetic Result

Patients frequently request treatment to enhance their smile due to dissatisfaction with the color and/or shape of individual teeth, arch contour, tooth spacing, or missing teeth. Facial and smile esthetics are interrelated, as a strong correlation exists between intraoral tissues and the face.^1,2 While the maxillary anterior teeth are the main components that can compromise a smile, the gingiva, lips, and other facial formations are also key elements.³ Before treatment can be started, a correct diagnosis and treatment plan must be made.

The anterior section of the mouth engages in esthetics, phonetics, protrusion, and often lateral guidance (usually canines).⁴ An esthetic treatment should encompass a tooth’s crown and the gingival tissues. Tooth shape and color are considerations for an esthetic smile and are main indications for porcelain veneers. Color can be modified by bleaching or microabrasion, while tooth shape may require composite placement or ceramic restorations.⁵

In the case presented, the prosthetic rehabilitation involved adhesive overlays, porcelain veneers, an implant-supported crown, and cantilevered ceramic resin-bonded fixed dental prostheses (FDPs). Ceramic veneers were considered the most conservative long-term solution to improve the patient’s appearance, as she had extensive discolored composite restorations.⁵ Merely replacing the composites would have provided only a relatively short-term improvement because of the composite staining and the teeth’s darkening.

The replacement of a single central incisor with an implant, as would be necessary in this case, requires thorough planning and discussion among the restorative dentist, implantologist, and patient. Contouring of the peri-implant tissue after the surgery is essential to create an appropriate silhouette of the peri-implant tissue before taking the final impression. Another challenge involves accomplishing a well-balanced esthetic appearance of the anterior teeth despite the presence of different substrates. In this case, an implant-supported crown (zirconia with a titanium base and cutback for porcelain placement) would be used to replace the left central incisor, while the right central incisor would be restored with a ceramic veneer. The cutback zirconia must be the same shade as the adjacent tooth prepared for the veneer, and the thickness of the porcelain should be the same to achieve a shade match.⁶

Restoring some of the patient’s molars in this case required deep margin elevation (DME) to avoid subgingival margins. As subgingival margins increase, capturing good impressions and properly isolating adhesive cementation becomes more challenging. DME was first proposed in the literature in 1998 to address the various clinical problems that accompanied subgingival margins, which are relocated coronally by DME using composite resin restorations.^7,8 Immediate dentin sealing (IDS) was incorporated in the present case to improve adhesion and minimize or eliminate postoperative sensitivity. The IDS concept entails the use of an adhesive system on freshly cut dentin, thereby creating an uncontaminated hybridization of fresh dentin. IDS aims to eliminate bacterial contamination and reduce sensitivity.⁹ Ozer et al found that IDS application improves the bond strength of indirect restorations to dentin and lessens the adverse effects of temporary materials on the bond durability of final restorations.¹⁰ The patient in this case was missing her mandibular first premolars, yet the spaces were inadequate for implant placement. Cantilever bonded ceramic FDPs would be used to fill the spaces and improve both function and her smile.^11,12

Case Report

A 37-year-old female patient presented to the esthetic dentistry department at New York University College of Dentistry wanting to enhance the appearance and color of her teeth. She wished to “show more teeth” when she spoke and wanted the “gaps” filled between her teeth. The initial clinical examination included an intraoral analysis of occlusion, periodontal health, existing restorations, and lateral and protrusive movements, along with digital radiography, photography, and videos of her expressing her chief complaint. The patient had a history of unsatisfactory orthodontic treatment and was averse to it. Tooth No. 9 was deemed nonrestorable due to external resorption (Figure 1 and Figure 2). She was referred to the periodontal department for extraction and consideration of implant placement.

Approximately 3 weeks after tooth No. 9 was extracted, with soft-tissue healing completed, photographs were taken as part of an esthetic evaluation and to examine various aspects of the patient’s dentition. Photographs included: lips in resting position; discrete smile (initial tooth display) (Figure 3); Duchenne smile (total tooth display); lateral view of forced smile (total tooth display in right and left lateral views) (Figure 4); retracted view (showing details of periodontal architecture and general anatomy) (Figure 5); full facial view (teeth in relation to face) (Figure 6); 12 o’clock view; and maxillary (Figure 7) and mandibular (Figure 8) occlusal views.

Diagnostic impressions were taken using vinyl polysiloxane (VPS) impression materials (3M™ Express™ XT Putty Soft and 3M™ Imprint™ II Monophase, 3M Oral Care, 3m.com) and stone casts. A dento-facial analyzer (Kois Dento-Facial Analyzer, Kois Center, koiscenter.com) and facial reference glasses (Kois Facial Reference Glasses, Kois Center) were used to register and transfer the patient’s occlusal plane. The dento-facial analyzer helps dentists capture a patient’s occlusal plane and facial midline in three dimensions for accurate diagnostic and restorative purposes. It involves aligning the analyzer with the patient’s facial midline and incisal edge, then capturing the occlusal plane’s tilt and steepness. This allows for precise mounting of maxillary casts on an articulator, helping to ensure functional and esthetic predictability. The authors produced an occlusal bite registration in the maximum intercuspal position (MIP) and created a diagnostic wax-up, incorporating changes the patient desired. A direct intraoral preliminary prototype was then fabricated using bis-acryl composite resin (Luxatemp®, DMG America, dmg-america.com) and a VPS putty matrix (Lab Putty, Coltene, coltene.dental).

The restorative treatment plan for the maxillary arch included an implant restoration at No. 9, porcelain veneers on teeth Nos. 6 through 8, 10, and 11, a vonlay/crown on tooth No. 5, a porcelain veneer (if the patient decided she wanted it for esthetic reasons) on tooth No. 12, and a crown on tooth No. 3 and vonlay on No. 14 for better occlusion. For the mandibular arch the treatment plan entailed at-home bleaching, a composite/ceramic onlay on tooth No. 19 for better occlusion, a crown/onlay on tooth No. 30, an enameloplasty on the lower incisors if necessary, and cantilever fixed dental prostheses to replace missing teeth Nos. 21 and 28. The risks and benefits of the treatment, including the materials and methods to be used, were discussed with the patient, who assessed and accepted the plan. The case was sent to the laboratory for a final wax-up and restoration in MIP.

Phase 1: At-home Bleaching

The initial phase of treatment involved at-home bleaching of the mandibular arch with a whitening gel (Opalescence™, 10%, Ultradent, ultradent.com). The patient was instructed to place a continuous gel bead approximately halfway up the facial side of the whitening tray from molar to molar, then insert the tray into her mouth and lightly tap it into place to adapt it to the sides of her teeth. She was told to wear the whitening tray for 8 to 10 hours or overnight.

Phase 2: Surgical Grafting and Implant Placement

Three weeks after the extraction of tooth No. 9 an initial cone-beam computed tomography (CBCT) scan was performed to assess the residual ridge, revealing extensive bone resorption. At this time a staged bone grafting approach was used for the surgical procedure associated with the No. 9 site, utilizing an allograft (Straumann® AlloGraft, Straumann, straumann.com) combined with a resorbable minimally cross-linked porcine peritoneum collagen membrane (Straumann® Membrane Flex, Straumann) (Figure 9 and Figure 10). A tenting screw was used to sustain the graft, which combined the structural characteristics of cortical and cancellous bone in one product. The graft was used to augment the deficient bone volume, with the resorbable membrane providing structural support and preventing soft-tissue encroachment. The membrane was tacked into position, and primary closure was achieved at the end of the procedure. It was anticipated that the membrane would dissolve over the course of 3 months as the human body simultaneously generates new collagen.

After a 6-month healing period, a new CBCT was taken to evaluate the resultant bone morphology and confirm the achievement of adequate ridge width for implant placement. The imaging results indicated successful bone regeneration, allowing for the placement of a bone-level tapered implant (Straumann) with dimensions of 4.1 mm in diameter and 10 mm in length. The implant was thus inserted (Figure 11). After another 3 months, during which time the implant integrated into the bone, the authors conducted a second-stage surgery to expose the implant and proceeded with an implant-level impression for fabrication of a screw-retained temporary crown (Figure 12 and Figure 13).

Phase 3: Restorative

All procedures were performed under rubber dam isolation, and local anesthesia with lidocaine 2% 1:100,000 was administered. Amalgam was removed from tooth No. 3, IDS was then initiated, a core buildup was performed (Ti-Core®, EDS, edsdental.com), and the tooth was prepared for a crown. A provisional crown was fabricated with Luxatemp and cemented with a temporary dental cement (Temp-Bond™, Kerr, kerrdental.com). The tooth No. 4 amalgam restoration was removed, and the tooth was built up with Ti-Core before crown preparation.

Next, the amalgam and composite restorations on teeth Nos. 18 and No. 19, respectively (Figure 14), were removed. The preparations were cleaned with a 2% chlorhexidine antibacterial scrub (Consepsis™, Ultradent). A selective-etch technique was used on the enamel for 30 seconds, and then a self-etch approach was utilized on the dentin and the enamel for 20 seconds with a bonding agent (G2-Bond Universal, GC America, gc.dental/america). The bonding agent was then air-dried and light-cured with a curing light (Valo™, Ultradent). This was followed by placement of a thin layer of flowable composite (G-ænial™ Universal Flo, GC America), and light-curing was performed to seal the dentin immediately (Figure 15). Direct composite restorative (3M™ Filtek™ Supreme, 3M Oral Care) was placed in tooth No. 18 using shade A2D, and ochre staining to match the tooth shade was applied. Tooth No. 19 was prepared for an onlay, with Telio® (Ivoclar, ivoclar.com) used as a provisional.

At the next appointment, the authors removed the old restorations in tooth No. 14 using the same protocol of immediate dentin sealing, and the tooth was prepared for an onlay with a Telio provisional. During the subsequent appointment, after removal of the old amalgam, a direct composite was placed in tooth No. 31 with the same protocol.

Placement of individual posterior restorations.The provisional restorations on teeth Nos. 3, 4, 14, 19, and 30 were removed and the preparations were cleaned with the aforementioned antibacterial scrub (Consepsis). The definitive ceramic restorations were tried in individually and together to verify fit and contacts and shown to the patient, who permitted the bonding of the restorations. The authors performed a selective-etch technique (using phosphoric acid 37% on enamel only), and areas treated with IDS were micro-etched with 50 microns of aluminum oxide. They then applied a universal bonding agent (Adhese®, Ivoclar) to the internal aspect of the preparations and performed light air-drying, but not light-curing.

The restorations were cleaned with a cleaning paste (Ivoclean®, Ivoclar) and rinsed. A universal primer (Monobond Plus®, Ivoclar) was then applied and air-dried. A neutral shade of resin-based adhesive (Variolink® Esthetic LC System Kit, Ivoclar) was placed on the lithium-disilicate restorations, which were then inserted into the corresponding teeth and light-cured (Valo) for 60 seconds on the occlusal, buccal, and lingual aspects. Resin-based adhesive (Variolink® Esthetic DC System Kit, Ivoclar) in a neutral shade was placed to bond tooth No. 30. The occlusion was verified in MIP and excursive movements. Shimstock occlusion foil was used to confirm the occlusion and hold the first and second molars on both sides of the dentition.

Bonded cantilever ceramic fixed dental prostheses.Teeth Nos. 20 and 29 were reshaped on the mesial and lingual aspects to reduce the contour heights to create guide planes and increase the enamel bondable surface. A slight reduction and elimination of sharp angles on the occlusal surface created at least 0.5 mm clearance for the zirconia restorations. Impressions were obtained with VPS material (3M™ Imprint™ 4, light- and heavy-body, 3M Oral Care), and bite registration in MIP was recorded (Blu-Bite® HP, Henry Schein, henryschein.com). The laboratory then designed the FDPs (Figure 16 and Figure 17), which were fabricated with multilayer zirconia (ArgenZ HT+ Multilayer Zirconia, Argen, argen.com) (Figure 18).

The authors tried in the FDPs to verify the fit and contacts, cleaning the internal aspects (Ivoclean) and then sandblasting them with 50 microns of aluminum oxide, before rinsing and drying them. An esthetic cement (Panavia™ V5, Kuraray, kuraray.com) was used to bond the FDPs. Adhesive primer (Clearfil™ Ceramic Primer Plus, Panavia V5 tooth primer, Kuraray) was placed on the intaglio surfaces for 15 seconds and air-dried. The abutment teeth were cleaned with the antibacterial scrub (Consepsis), rinsed with water, etched with phosphoric acid for 15 seconds, then rinsed and air-dried. Tooth primer (Panavia V5) was applied for 20 seconds and air-dried. Cement was then placed on the intaglio of the restorations, which were then placed on the corresponding abutment teeth. Excess cement was removed using a microbrush, and the margins were light-cured while held in position for 3 minutes. Occlusion was verified in MIP and excursive movements and adjusted as needed for all posterior restorations (Figure 19 and Figure 20).

Porcelain veneers Nos. 6 through 8 and 10 through 12 with implant-supported crown No. 9.New composite restorations (3M™ Scotchbond™ Universal Adhesive and 3M™ Filtek Supreme Ultra, shade A1, 3M Oral Care) were placed in teeth Nos. 8, 10, and 11. Teeth Nos. 6 through 8 and 10 through 12 were prepared for porcelain veneers. The contact points needed to be moved, so the authors moved the preparations to the lingual. Incisal and sagittal putty indices were used to check for adequate reduction. The provisional laboratory-fabricated crown on No. 9 was removed, and an individualized transfer was created that the authors modeled according to the provisional crown.¹³ Retraction cord (000 Ultrapak™, Ultradent) was placed around teeth Nos. 6 through 8 and 10 through 12, and an open tray impression was taken for No. 9 and the veneers. Only one cord was used due to the patient’s thin biotype and the concern for recession.

Two weeks later the provisionals were removed and the restorations tried in individually to verify fit and check interproximal contacts. A neutral try-in paste (Variolink) was used to demonstrate the esthetic potential of the restorations to the patient, who accepted them. The veneers were bonded with a universal bonding agent (Adhese) and neutral cement (Variolink LC). The implant crown was screw-retained, torqued to 35 Ncm, and then the screw access was sealed with Teflon tape and composite on the lingual. All excess cement was removed from the veneers with a #12 blade, and the occlusion was checked in centric relation and excursive movements. The patient verified that the improvements in her smile were satisfactory (Figure 21 through Figure 23).

Discussion

Occlusal renewal and esthetic design should focus on rebuilding teeth and creating a healthy stomatognathic system.¹⁴ An accurate implant impression is needed to replicate the fixture location and the surrounding soft tissue to enable a predictable outcome in the final restoration. The emergence profile of the definitive restoration will affect its durability and consistency. The provisional restoration helps prevent soft-tissue collapse, and proper contouring facilitates ideal esthetics. An analog technique for taking the impression requires the fabrication of a custom impression coping that replicates the contours and position attained by the provisional restoration. Other methods require a scan body, but any collapse of the soft tissue during the scan can lead to flaws in capturing the precise profile architecture.¹⁵

Restoring posterior teeth differs from restoring anterior teeth, as forces directed at the former are of greater amplitude and come from different directions. Posterior teeth protect their anterior counterparts by supporting vertical compressive forces, while anterior teeth protect those in the posterior from the tensile stresses of protrusive and lateral movements. Clinicians must consider the remaining posterior tooth structure when fabricating an adhesive restoration. The depth of the preparation and the wall thickness help determine cuspal coverage. Posterior teeth also need more substantial restorative material. Ceramic materials such as lithium disilicate in the etchable ceramic group or zirconia can provide a high fracture resistance when monolithic. Cardoso et al provided guidelines for the selection of restorative techniques. Placement of feldspathic porcelain in a functional area to enhance the esthetics of lithium disilicate or zirconia can sometimes invite chipping. Whether or not a ceramic restoration will be long-lasting may depend on the adhesion of the restoration to both enamel and dentin. Rubber dam isolation is the primary method to secure and prevent contamination.^16,17

Replacing an absent single tooth can be accomplished via several restorative alternatives, such as a conventional or resin-bonded dental prosthesis, a single dental implant, or a removable prosthesis. In the present case, in the areas of the missing mandibular first premolars, there was inadequate space for an implant, and one adjacent tooth had no restorations. A resin-bonded FDP is considered a highly conservative option for replacing missing teeth; the original design utilized metal and multiple abutments.¹⁷ Several CAD/CAM programs permit the design and milling of yttria-stabilized polycrystalline (Y-TZP) ceramics. Materials such as Y-TZP have notable flexural strength and fracture toughness attributes.¹⁸ Shahdad et al found that single-tooth cantilever resin-bonded bridges fabricated from Y-TZP ceramic are a viable and esthetic option.^19,20 The current recommendation is to sandblast the Y-TZP with 50 microns aluminum oxide and 0.25 bar pressure combined with an adhesive monomer (in this case, Panavia V5). This method is called the APC approach and comprises three simple steps: (1) airborne-particle abrasion, (2) application of a zirconia primer containing 10-methacryloxydecyl dihydrogen phosphate (10-MDP), and (3) use of adhesive composite resin.^20,21

The ceramic resin-bonded FDP is easy to employ, needs only moderate tooth preparation, incurs a relatively low cost, and is somewhat reversible. This treatment option carries no risk of pulp irritation, needs no anesthesia, has a negligible caries risk, and requires nominal preparation of only one abutment tooth compared to the necessary preparation of two abutment teeth in the case of a three-unit bridge. The lab created the restorations digitally using CAD/CAM technology, and the preparations, as indicated previously, were confined to the enamel except where a previous restoration existed. A minimum thickness of 0.7 mm of the retainer wing was created, and a bonding surface of 30 mm² of sound enamel was produced by reducing the height of the contour and extending to the proximal ridge and cusps in areas without occlusal contact. The proximal heights of the contour were removed to achieve a vertical path of insertion and increase enamel coverage.²⁰ The size of the proximal connectors was 3 mm horizontal by 3 mm vertical. Occlusal guidance on the pontic was eliminated.

Conclusion

Dental interventions must consider the ramifications of the treatment on facial features and occlusion. Proper diagnosis, appropriate treatment, and restorative material selection are crucial elements to improving esthetics and occlusal function and attaining long-term success. In the present case, the authors selected the most suitable ceramic material and adhesive technique for anterior and posterior restorations to provide an excellent esthetic outcome and occlusal function.

ACKNOWLEDGMENT

The authors thank Crystal Tang Li, CDT, and Robert Hopkins, MDT, of New-Dent Aesthetics for their excellent ceramic restorations.

ABOUT THE AUTHORS

Chiara Burgio, DDS
Private Practice, London, England

Benedetta Grassi, DDS
Private Practice, Chicago, Illinois; Diplomate, International Congress of Oral Implantologists

Richard D. Trushkowsky, DDS
Adjunct Clinical Professor, General Dentistry and Comprehensive Care, Associate Director, International Program in Advanced Esthetic Dentistry, New York University College of Dentistry, New York, New York

Ye Shi, BDS, MS
Clinical Assistant Professor, Periodontology and Implant Dentistry, New York University College of Dentistry, New York, New York

Figures and Images

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Figure 1

Fig 1. Pretreatment radiograph of tooth No. 9 with external resorption.

Figure 2

Fig 2. Pretreatment clinical view of tooth No. 9 with external resorption.

Figure 3

Fig 3. Discrete smile showing initial tooth display.

Figure 4

Fig 4. Lateral view of forced smile.

Figure 5

Fig 5. Frontal view with lip retractors revealing the patient’s soft tissue and general anatomy.

Figure 6

Fig 6. Full facial view showing the relationship of the teeth to face.

Figure 7

Fig 7. Maxillary occlusal view.

Figure 8

Fig 8. Mandibular occlusal view.

Figure 9

Fig 9. Placement of allograft material.

Figure 10

Fig 10. Placement of resorbable membrane.

Figure 11

Fig 11. Insertion of implant No. 9.

Figure 12

Fig 12. Occlusal view of the cover screw on implant No. 9. Note the recovery of the width of the ridge. The provisional crown will mold the soft tissue.

Figure 13

Fig 13. The laboratory-fabricated provisional (No. 9) in place to develop the final soft-tissue profile.

Figure 14

Fig 14. The lower left quadrant with existing amalgam and composite.

Figure 15

Fig 15. After the existing restorations were removed from teeth Nos. 18 and 19 and the teeth were cleaned with antibacterial scrub, flowable composite was placed, as shown, for immediate dentin sealing. Direct composite would subsequently be placed in tooth No. 18, while tooth No. 19 would be prepared for an onlay.

Figure 16

Fig 16. Occlusal view of the laboratory design of the cantilever FDPs.

Figure 17

Fig 17. Labial view of the laboratory design of the cantilever FDPs.