429 Too Many Requests

Case by Dt Giuliano Moustakis

When producing restorations for the upper anterior region, the first thing that comes to a dental technician’s mind is the selection of a material that matches the colour and translucency of the patient’s natural teeth. The aim behind this action is to provide a perfect optical integration of the restorations to be produced. In order to achieve this optical integration, however, dental technicians need to focus on the surface morphology as well. The following clinical case is used to demonstrate how restorations with the right colour, translucency and texture are able to create a stunning, natural smile, even in complex cases.

The female patient had a periodontally compromised dentition with a missing maxillary lateral incisor and mandibular prognathism. Spacing was present in both jaws, but the patient decided not to undergo orthodontic treatment due to the challenging periodontal situation and the associated risk of losing additional teeth. Instead, a cosmetic camouflage was planned. As the existing direct restorations on the upper central incisors were in need of replacement, the restoration of choice was an all-ceramic, five-unit bridge. Knowing that this situation would best be solved with a material that offers high flexural strength in the body area (strictly mandatory for five-unit bridges) and high translucency in the enamel part (required to imitate nature in the anterior region), the new KATANA™ Zirconia YML was selected. Thanks to its multi-layer structure with colour, translucency and flexural strength gradation (achieved through yttria content gradation), this material offers exactly the desired properties. We decided to use it with a slight vestibular cutback and microlayering with CERABIEN™ ZR (CZR) porcelain.

Fig. 1 Pre-operative clinical situation with a Class III Malocclusion, a missing lateral incisor, spacing and periodontally compromised teeth in both jaws.

Fig. 2 Lateral view of the pre-operative situation.

Fig. 3 Shade determination in the dental office.

Fig. 4 Maxillary central and lateral incisors and right canine after tooth preparation.

Fig. 5 Printed models of both jaws based on an intraoral scan. This view reveals the discrepancy between the upper and lower jaws that needs to be camouflaged.

Fig. 6 Vestibular and incisal reduction and surface texturing on the pre-sintered restorations made of KATANA™ Zirconia YML. Integration of mamelon structures with a round-end straight carbide bur.

Fig. 7 Integration of horizontal growth grooves with a coneshaped instrument (Panther Stone 040).

Fig. 8 Translucency of the reduced bridge after sintering.

Fig. 9 KATANA™ Zirconia YML structure on the model after sintering.

Fig. 10 Silicone index revealing the space generated in the cutback procedure.

Fig. 11 Evaluation of the camouflage effect.

Fig. 12 Try-in of the zirconia structure.

Fig. 13 Sandblasted bridge ready for microlayering.

Fig. 14 Bridge after the application of internal stains and a single layer of CERABIEN™ ZR Body (A3B) and CERABIEN™ ZR Luster Porcelain (LT1, LT Royal Blue, LTx and LT Coral mixed with Incisal Aureola).

Fig. 15 Chromatic map of the microlayering procedure.

Fig. 16 Palatal view of the restoration.

Fig. 17 Bridge after the first bake and the addition of LT1.

Fig. 18 Finished restoration. In order to optimize the look of tooth and gingiva parts, a final layer of CERABIEN™ ZR FC Paste Stain and Glaze was added.

Fig. 19 Palatal view of the restoration after finishing.

Fig. 20 Try-in of the bridge for aesthetic and functional evaluation.

FINAL SITUATION

Fig. 21 Treatment outcome.

CONCLUSION

This clinical case shows that KATANA™ Zirconia is an innovative material with high aesthetic potential. Despite flexural strength gradation, there are no severe design restrictions that limit the indication range. Instead, it is easy to design and produce even long-span bridges. Furthermore, due to the material’s high aesthetic potential, a monolithic design with zero cutback and paste staining with liquid ceramics is often an option. If users want to add a porcelain layer, a simplified and time-efficient microlayering approach is highly recommended. In any case, a natural surface morphology should be integrated, as it is essential for an aesthetic outcome.

Case by MDT Daniele Rondoni

Usually, the aesthetic potential of a dental ceramic material – specifically its translucency – may be increased only at the expense of a decreased flexural strength. The new KATANA™ Zirconia YML from Kuraray Noritake Dental Inc. is different. With its high flexural strength of 1,100 MPa in the lower half of the blank and high translucency in the upper body and incisal areas, it has a high aesthetic potential and an unlimited indication range, as shown using the following case example.

Fig. 1. KATANA™ Zirconia YML 4-unit and 6-unit bridges after milling and sintering. A natural vestibular surface texture plays a decisive role in the creation of aesthetic monolithic restorations.

Fig. 2. The two bridges on the model after ultra-micro layering with CERABIEN™ ZR FC Paste Stain Kuraray Noritake Dental Inc.).

Fig. 3. Stained and glazed restorations and their translucency in transmitted light.

FINAL SITUATION

Fig. 4. Buccal view of the 6-unit bridge cemented in the patient’s mouth.

Fig. 5. Buccal view of the 4-unit bridge cemented in the patient’s mouth.

With this new type of multi-layered zirconia, it is possible to produce aesthetic monolithic restorations suitable even for use in the anterior area. A high design flexibility is offered despite strength gradation, and the high translucency in the incisal area is responsible for a natural look after sintering. Ultra-micro layering and glazing on the monolithic surface will be sufficient to produce outcomes to our patients’ satisfaction.

Case by Dr. Daniele Rondoni, RDT

Check out how beautiful zirconia restorations are finalized using CERABIEN™ ZR FC Paste Stain, take a look at the color palette used by Dr. Daniele Rondoni to achieve outstanding aesthetic results.

“CERABIEN™ ZR Paste Stain is a material developed for micro-layering on the full-contour zirconia surface. With it, natural, true-to-life optical effects are created in an efficient way. I apply the pastes in the esthetic areas, while the functional parts of the restorations are only polished.”

Case by Francesco Ferretti and Marco Nicastro

Aesthetic restoration of anterior teeth using KATANA™ UTML Full anatomical crowns, with vestibular stratification and BOPT*¹.

^{*1 Biologically Oriented Preparation Technique}

Initial situation

Final result

Shows excellent aesthetic properties of KATANA™ UTML and the perfect integration in harmony with pink tissues.

Figure 1. The patient requested a solution for an aesthetic problem due to unnatural look of old restorations and black triangles coming from past history of periodontitis. The resulting retraction of the tissues had left the margins of the prosthesis clearly visible, and the loss of the papilla peaks, together with the numerous black spaces between the crowns, required a complex therapeutic approach.

Figure 2. The treatment plan for the periodontal problems con-sisted of a non-surgical approach, with scaling and root planing, and the replacement of the previously fixed prostheses to recondition the marginal tissues and facilitate the restoration of a new, aesthetically pleasing gingival architecture.

Figure 3. From a functional point of view, we decided to reduce the deep frontal bite to restore a correct overjet-overbite ratio. This reduction was also important from an aesthetic point of view, as it allowed us to shape the various elements correctly.

Figure 4. We usually remove old prostheses before beginning a periodontal treatment, and make a first, provisional restoration to create an environment in which the soft tissues can heal. If we have to work beyond the cement enamel joint (CEJ), we prefer a vertical preparation for posts, and the purpose of the provisional restoration is to condition the marginal tissues using Dr. Loi’s BOPT.

Figure 5. For the BOPT, the vertical preparation of the post has a finish line that extends inside the gingival sulcus. The temporary conditioning of the tissues induced by the provisional prosthesis allows us to modify the level of the gingival parables to a certain extent.

Figure 6. The image on the left shows the clinical healing of the tissues one month after the initial periodontal treatment. The role of the provisional restoration, appropriately realigned, is clear. The conditioning of the tissue has been achieved by means of the provisional restoration, which has modified the level and shape of the marginal tissue. Once filled with correctly fitted crowns, the interproximal spaces will be further reduced after the definitive restoration.

Figure 7. The correct management of the provisional restoration is crucial for the healing of the tissues. The placement of a provisional restoration before the periodontal therapy has allowed us to create the right environment for complete healing. At the same time, the vertical preparation has allowed us to gradually condition the marginal gingival tissue by shortening or lengthening the provisional restoration as necessary.

Figure 8. One of the advantages of a vertical preparation is that taking the final impression is easy, because the absence of a horizontal finish line greatly simplifies the procedure. On the other hand, the BOPT also requires the taking of an impression of the sub-gingival portion of the preparation. The dental technician will have to decide marginal shape of restorations according to the position of the gingival line in consultation of the clinician, and based on the tests conducted with the provisional restoration.

Figure 9. After the casting of the model, we prepared the gingival area to accommodate an ideal configuration of gingival parables.

Figure 10. After making a wax model, we assessed whether the height of the gingival zenith level could be further corrected. This photo shows that gingival level of 21 was not yet ideal, so we stretched it distally.

Figure 11. Once the wax model was complete, we extracted the element from the model and evaluated its protrusion. It was only after joining the gingival protrusion to the arbitrary margin of the preparation that we proceeded to a scan and milled the crowns.

Figure 12. The restoration was carried out with Katana™ UTML zirconia based on the new formulation of cubic zirconium oxide. This ultra tralucent material was chosen because we were working with light and non-discolored posts.

Figure 13. We finished the crowns on a positional impression to help to improve the gingival adaptation; we had some dispersion of the tissues in the first precision impression due to the use of retractors. We finished the crowns with CZR FC Paste Stain colours and glaze.

Figure 14. The surface colours and the slight contrast created are highlighted in this black-and-white image taken with a blue filter.

Figure 15. In this translucent image, we can see the natural translucent effect of KATANA™ UTML and invisible fusion between abutments and crowns.

Figure 16. Clinical image one year after cementation made with PANAVIA V5; this shows the good clinical condition of the marginal tissue, with no signs of inflammation or bleeding. The BOPT allowed us to optimise the level of the gingiva without resorting to periodontal surgery, while the shape of the new crowns has made it possible to close all interproximal spaces for an optimally aesthetic result.

Figure 17. The brightness of the restorations (thanks to the use of a particularly translucent zirconia) combined with the shape of the incisors, has greatly im-proved the aesthetic of the restoration, even though the condition initially appeared to be particularly unfavourable.

Figure 18. Compared to the previous prostheses, the incisal reduction allowed not only for the optimisation of the functional phase by reducing the overbite, but also made it possible to achieve a more natural aesthetic, with the contour of the incisal margins following that of the lower lip.

By Daniele Rondoni, RDT

Considering different criteria to select the ideal zirconia and frame design to meet the level of esthetics requested.

Step 1
Final Preparations.

Step 2
Zirconia Frame (KATANA Zirconia STML A2) cut-back designed to reproduce translucent incisal area.

Step 3
Application of 1st Internal Stain and firing.

Step 4
Application of 1st Luster, Clear Cervical and firing.

Step 5
Application of 2nd Internal Stain and firing.

Step 6
Application of 2nd Luster, and Opacious Body.

Step 7
Completion of firing.

Step 8
Completion of morphological correction.

Step 9
Post-operative view.

By Daniele Rondoni, RDT

Preoperative view

1 PFM. 3 Laminates on refractory

Postoperative view

NORITAKE SUPER PORCELAIN EX-3 CHROMATIC MAP

By D.T. Pier Francesco Golfarelli

Digital workflow and CAD/CAM shaping have now become a daily practice that helps to manage most cases, including the most extensive re-adaptations (rehabilitations).

KATANA™ HTML zirconia was selected, in consultation with the specialist, for the case presented here. It was principally chosen for its aesthetic and mechanical properties. One of our selection criteria was the advantageous lower abrasiveness level of zirconia. Because of its density, this material is less abrasive than the more traditional ceramics in combination with adequate mechanical polishing. Based on the initial situation, once the assembly in the articulator was completed, we designed a structure with anterior cutbacks for maximum aesthetics, while for the posterior teeth a monolithic solution was chosen for maximum strength and quality of the functional surfaces.

With the CORE & SHELL technique developed by the Noritake Italian Study Club, I can now fully exploit the optical properties of KATANA™ zirconia by integrating it, in the anterior area, with Noritake CERABIEN™ ZR ceramics. In the images here you can see the aesthetic results of the anterior and side areas, the mechanically polished monolithic surfaces and the special Noritake glaze.

Fig. 1 CAD Shaping - 3Shape Dental Designer

Fig. 2 Structure design with cutbacks

Fig. 3 KATANA™ HTML structure

Fig. 4 Occlusal surface – details

Fig. 5 Shade stain

Fig. 6 Shade Stain (SS)

Fig. 7 Core

Fig. 8 Internal Live Stain (ILS)

Fig. 9 Shell

Fig. 10 Shell Tissue

FINAL SITUATION

Fig. 11 Layering Details

This case was conducted by Dr Davide Cortellini, owner of Studio Cortellini in Riccione in Italy, and dental technician Angelo Canale, owner of Canale dental laboratory in Rimini in Italy.

This patient came to the clinic to improve her chewing ability and aesthetic level. The physical examination revealed the presence of several endogenous erosive lesions that made chewing difficult, in addition to partly affecting the esthetics due to decrease in enamel thickness and the presence of dyschromic composite restorations. The possibility of using the new types of both tetragonal and cubic multilayer zirconia made it possible for us to plan the complete covering of all the elements with extremely conservative crowns with thicknesses between 0.5 and 1 mm in the axial and occlusal areas and up to 0.2 mm at the margin.

VERTICAL PREPARATIONS

Very conservative vertical preparations were carried out in the enamel without anesthesia. In the upper arch, the front group was prepared for full-veneer crowns, while the lower front group was treated with conventional lithium disilicate veneers without interproximal separation. In this case too, vertical preparations were carried out without finishing line. The impression was made using a 3Shape TRIOS intraoral scanner. The technician modeled the zirconia restorations that were then completed by the ceramist.

Knife Edge Preparation

SCANNING SEQUENCE

Digital DV models of temporary teeth

The three different materials were selected on the basis of the specific positions inside the mouth:

• UTML for the anterior teeth
• STML for the premolars
• HTML for the molars

The final result shows excellent integration between the 3 different types of zirconia and a good natural feeling.

MINIMAL PREP KATANA™ (KATANA™ MICRO LAYER)

HARMONIC OPTICAL INTEGRATION

The full-mouth rehabilitation procedure using three different types of zirconia led to a functional and beautiful treatment outcome. The optical integration between the materials is excellent and the high translucency especially in the anterior region creates a true-to-life appearance.

APPROACH WITH MINIMAL INVASIVE PREPARATIONS - REPORT ON THE SELECTION OF MULTI-LAYERED ZIRCONIA

Dental zirconia is no longer just the opaque framework material introduced two decades ago. Nowadays, it offers the high strength needed for long-span bridges, dentin-like translucency and strength perfect for thin-walled posterior crowns, or enamel-like optical properties for beautiful anterior restorations - depending on its composition and structure. Kuraray Noritake offers three types of dental zirconia - three with a multilayered structure created using patented powder coloring technology. They differ with regard to their optical and mechanical properties, which makes it possible to choose an ideal material for every clinical situation.

By Dr Salvatore Scolavino and DT Francesco Napolitano 

The dental laboratory is confronted with the greatest aesthetic challenge whenever it comes to the restoration of a single incisor with natural adjacent teeth. In the following case, a young patient had undergone endodontic treatment of her tooth 21 (fig. 1) while all other teeth showed their natural appearance. Tooth 21 was due for replacement now (fig. 2).

Fig. 1:  X-Ray after endodontic treatment (with new crown on tooth 21 in place).

Fig. 2: The former restoration with which the patient showed up in the dentist’s practice.

To keep the natural identity, together with preserving the gingiva outline, the decision was taken in favour of a monolithic zirconia restoration, with a layered block for a full-contour crown. KATANA™ Zirconia STML (Kuraray Noritake Dental) provides for four gradational layers from „Body/Dentine“ (cervical area) to „Enamel“ (incisal aera), varying in chroma and translucency. Using this kind of milling block, it is possible to imitate the natural progression from yellowish to whitish-blue, and this in an easy manner. At the same time this way, the endodontic post wouldn’t shine through and make any aesthetic difference. On the other hand, the zirconia irradiates into the gingiva and results in a natural looking shade allover the anterior area. Furthermore for a lively and most natural-identical appeal, it was intended to individualize the crown by surface stains. With the product CZR™ FC Paste Stain by Kuraray Noritake Dental, 27 shades are available, together with fluorescence. What is essential in the front, too, is this well proven experience: All zirconia material enhances the close gingival attachment and provides for stable results of the pink-and-white aesthetics.

The dentist built up the stump 21, prepared it according to the specifications for zirconia and took the impression (fig. 3). The plaster model followed (fig. 4) and was scanned to start then the digital process. After designing, the crown was milled and tried-in at the next session with the patient (fig. 5).

Fig. 3: Impression taking after preparing tooth 21.

Fig. 4: Plaster model - the prothetic baseline of the case.

Fig. 5: Try-in of the zirconia crown in the patient’s mouth with rubber dam.

SHAPE AND COLOUR

Right when starting the case, the teeth of both jaws had been scrutinized: first for shape. Special attention was payed to the interproximale space between 11 and 21 because this area had worn out in the meantime (see again fig. 2). It was also necessary to move closer to each other the approximale margins 21/22 resp. 11/12 in their cervical-middle parts. When giving the zirconia crown its final shape, this resulted in a widely swinging outer line distally 21. For harmony reasons, tooth 11 was extended distally, too. Here, the clinician used the direct filling composite CLEARFIL MAJESTY™ Classic, shade A2 (fig. 6, 7 and 8). This nano-hybrid composite by Kuraray Noritake Dental is easy-sculpting and integrated fully with the milled crown.

It was most important for crown 21 and tooth 11 too, to create a 3D effect of the tooth structure and an age-appropriate vestibular surface texture. For this, the characteristics of the adjacent teeth and allover both jaws were examined meticulously in general and in detail. Surface burs, discs, stones, and similar instruments sophisticatedly engraved pericymatia and a groove here and there, thus accomplishing the perfect natural look.

Fig. 6: Tooth 11 before recontouring the shape distally.

Fig. 7: Finished crown 21 on the plaster model. Notice: In order to match the shape of crown 21 and close-up the margins 11/12, composite has been added in the interproximal space.

Fig. 8: Finishing the new distal outline of tooth 11.

The final colour touch was given to both teeth by surface staining: with a thin layer of FC Paste Stain measuring only 50-70 micrometers in depth, different shades were applicated. The entire range was used from yellow/orange to blue and white (fig. 9a-d) in order to provoke the effect of mamelons and other structures in all thirds of the restorations.

Fig. 9a: Definitive fitting of the restoration.

Fig. 9b: Directly after the fitting.

FINAL SITUATION

Fig. 9c: View of the lips with the restoration in place.

Fig. 9d: Natural look of the upper and lower jaws.

By Daniele Rondoni, RDT

Hybrid designing meets the functional needs in term of lower abrasiveness and higher toughness.

Step 1
Zirconia Frame (KATANA Zirconia HTML A2) cut-back designed to minic anatomical dentin structure and incisal frame.

Step 2
Application of Internal Stain.

Step 3
Completion of Internal Stain firing.

Step 4
Application of Luster, Clear Cervical and Opacious Body.

Step 5
Completion of firing.

Step 6
Completion of glaze (self-glaze) firing.

Step 7
Polishing of lingual side.

Step 8
Post-operative view.

4-Years Post-operative.