Andreas Chatzimpatzakis

Case by Andreas Chatzimpatzakis

For zirconia-based screw-retained implant-supported prostheses, diverse finishing concepts are available. Most of them are quite complex and time-consuming. A streamlined approach that brings efficiency into the finishing procedure without compromising aesthetics and function is micro-layering with CERABIEN™ MiLai (Kuraray Noritake Dental Inc.) on a zirconia superstructure with just a slight vestibular cutback. A possible technical procedure is demonstrated using the following case example. The patient was treated by prosthodontist Dr. Georgios Siavikis from Ioannina, Greece.

Fig. 1. Occlusal view of an implant-supported overdenture made of KATANA™ Zirconia HTML PLUS (Kuraray Noritake Dental Inc.) for a male patient with an edentulous maxilla and a removable partial denture in the mandible.

Fig. 2. Frontal view of the milled and sintered screw-retained implant-supported prosthesis.

Fig. 3. Appearance after the application of CERABIEN™ MiLai SS Fluoro and internal stains to enhance the natural shading of the restoration in the tooth and gum areas.

Fig. 4. Result of micro-layering with CERABIEN™ MiLai porcelains LT1 for the cervical as well as E2 and TX for the middle and incisal sections for a seamless gradient in translucency. For an optimal gingival harmony and match with the surrounding tissue, the tissue shades 1, 5 and 6 were applied.

Fig. 5. The restoration after finishing.

Fig. 6. The gingiva and tooth areas have a natural appearance …

Fig. 7. … due to a natural colour, translucency and surface texture.

Fig. 8. Intraoral harmony.

PREDICTABLE OUTCOMES

In this case, the use of an aesthetic, high-strength multi-layered zirconia was a true enabler of a streamlined finishing technique. As a convinced and frequent user of CERABIEN™ ZR, micro-layering with CERABIEN™ MiLai appeared to work flawlessly right from the start. The systems are perfectly aligned to each other, and as they are both based on synthetic feldspathic technology, they offer consistent material properties. These provide precise control over the layering and shading, thus supporting a highly aesthetic and well-integrated implant restoration.

Case by MDT Andreas Chatzimpatzakis and DDS Manousos Pissadakis

ONE SOLUTION, MULTIPLE NEEDS COVERED

The treatment of young patients with a dental condition that affects the appearance of multiple teeth – like enamel hypomineralisation or hyperplasia – is particularly challenging for the restorative team. Dental practitioners and technicians need to be aware of the fact that the condition often involves a life-long disease burden, which typically goes hand in hand with an immense treatment need and increasingly invasive measures required with advancing age. It is their task to make the situation as bearable as possible for patients by delivering treatment that is very well aligned to their specific aesthetic, functional and financial needs, both in the short and long term.

Whenever all-ceramic restorations seem most appropriate, material and technique selection are particularly important: Protection of the affected teeth from extrinsic influences, the saving of sound tooth structure and the safeguarding of the long-term stability of the restorations are key to success. Depending on the aesthetic expectations of the patient, veneers made of zirconia or lithium disilicate, produced with a minimal vestibular cutback and finished using the micro-layering technique, are a great option. A prime example of an innovative porcelain system specifically developed for this technique is CERABIEN™ MiLai (Kuraray Noritake Dental Inc.). It includes a collection of internal stains and porcelains that fire at just 740 °C. With this low firing temperature and a coefficient of thermal expansion between 9.5~11.0×10-6/K (50 °C – 500 °C), this product is ideal for use with lithium disilicate and zirconia. In addition, it offers impressive aesthetic capabilities: Depending on the specific needs of each case, users can adjust the level of complexity and number of bakes.

CASE EXAMPLE

In the present case of a young female patient with hypomineralisation, it was decided to follow a straightforward approach to restore the maxillary teeth for the time being. For this purpose, we produced a wax-up and transferred it into the patient’s mouth in the form of a mock-up. Following guided tooth structure removal trough this mock-up, an impression was taken. The restorations were designed in full contour, pressed using lithium disilicate-based press ingots (Amber® Press LTW3, HASS Corp.) and cut back slightly in the vestibular area (reduction: 0.3 mm). The selected micro-layering system was applied according to the internal stain technique. The following CERABIEN™ MiLai Internal Stains were used: A little Red in the cervical, and Mamelon 2, Incisal Blue 1 and White in the incisal third. What followed was build-up with CERABIEN™ MiLai Porcelains Tx incisally and LTx proximally; some whitish lines were created with Value Liner 1. Then, I applied a mixture of E2 and ELT1 in the middle and LT1 in the cervical area. After the bake, the restorations were treated with green stones, sandpaper and rubber wheels to pre polish the surface. After glazing with CERABIEN™ ZR FC Paste Stain Clear Glaze, final polishing was carried out.

The whole treatment procedure including tooth preparation, shade determination, veneer production and adhesive cementation is illustrated below.

Fig. 1. Portrait of the patient prior to treatment.

Fig. 2. Enamel defects in the maxilla and mandible.

Fig. 3. Initial clinical situation in the maxilla with whitish-brown discolouration and composite restorations in need of replacement.

Fig. 4. Mock-up in the patient’s mouth.

Fig. 5. Labial reduction through the mock-up: The depth of tooth preparation is controlled by using a depth guide and by marking the created depth grooves with a colour marker.

Fig. 6. Silicon index used to check the space created for the veneers.

Fig. 7. Prepared teeth ready for impression taking and temporization.

Fig. 8. Shade determination for the veneers.

Fig. 9. Pressed lithium-disilicate restorations on the model.

Fig. 10. Appearance of the restorations after internal staining.

Fig. 11. Appearance of the teeth after build-up with CERABIEN™ MiLai Porcelain.

Fig. 12. Final restorations on the model.

Fig. 13. Adhesive cementation procedure carried out for two teeth at once: Isolated teeth and a perfectly dry working field.

Fig. 14. Etching of the tooth structure with phosphoric etchant (K-ETCHANT Syringe, Kuraray Noritake Dental Inc.).

Fig. 15. PANAVIA™ V5 Tooth Primer (Kuraray Noritake Dental Inc.) applied to the etched tooth surfaces.

Fig. 16. Veneers – pre-treated with hydrofluoric acid and CLEARFIL™ Ceramic Primer Plus – filled with PANAVIA™ V5 Paste (Both from Kuraray Noritake Dental Inc.) and placed in the patient’s mouth.

Fig. 17. Restorations after excess removal.

Fig. 18. All eight restorations in place.

Fig. 19. Treatment outcome after two weeks.

Fig. 20. Portrait of the patient taken two weeks after treatment.

CONCLUSION

Repeated dental treatment, increasing invasiveness of the measures, often resulting in early tooth loss: To break the vicious cycle in young patients with enamel defects, it is important to carefully evaluate the treatment need and select the appropriate solutions. As dental technicians, we can contribute to long-term treatment success by using high quality materials and production techniques that allow us to create restorations that last.

The presented material combination and the micro-layering technique are very well suited as they offer the required mechanical and optical properties for high aesthetics and durability. Plus, the risk of complications is low due to the high biocompatibility and the layer of porcelain limited to non-load-bearing areas.

Case by Andreas Chatzimpatzakis

Many modern, tooth-coloured dental materials enable us to achieve more with less. By using high-strength ceramics with a multi-layered colour structure and natural translucency, for example, the path to the desired outcomes involves fewer components, smaller layers and a reduced number of bakes. A possible streamlined procedure is illustrated below. The main materials used were KATANA™ Zirconia HTML PLUS for the screw-retained implant-supported superstructure and CERABIEN™ MiLai (both Kuraray Noritake Dental Inc.) for vestibular micro-layering.

Fig. 1. Zirconia-based screw-retained implant-supported prosthesis after milling and carving to obtain a natural surface texture.

Fig. 2. Restoration after sintering. To intensify the colour characteristic of the multi-layered blanks, the surface was treated with Esthetic Colorant (mainly in the incisal area and the gum parts).

Fig. 3. Appearance after the application of CERABIEN™ MiLai SS Fluoro.

Fig. 4. Restoration after the application of CERABIEN™ MiLai internal stains. They add some natural shading effects to the tooth and gum areas.

Fig. 5. Restoration on the model after micro-layering. In the cervical area, CERABIEN™ MiLai LT1 was mainly used, while the middle and incisal areas were individualized with E2 and Tx, the latter adding a seamless gradient in translucency. For the gingiva, the choice fell on the tissue porcelains 1, 5 and 6.

Fig. 6. Finished restoration on the model.

Fig. 7. The micro-layer of porcelain has a brilliant effect.

Fig. 8. The lifelike appearance is due to a smart combination of surface texturing …

Fig. 9. … and micro-layering with a comprehensive set of internal stains plus porcelains.

CONFIDENCE AND CONTROL

Full ceramic layering can produce beautiful results, but can be quite complex and time-consuming. In times with limited availability of skilled personnel and high-performance materials being offered, it may be a valuable strategy to opt for micro-layering with CERABIEN™ MiLai whenever appropriate. The system provides precise control over the layering and shading procedure, so that highly aesthetic and functional outcomes are easily and confidently obtained.

Case by Andreas Chatzimpatzakis

A CONCEPT EVEN FOR AESTHETICALLY DEMANDING CASES

The micro-layering technique is regarded as a more efficient, streamlined approach used as an alternative for full porcelain layering. It requires aesthetic, high-strength ceramics like lithium disilicate or zirconia as a base and – ideally – a set of porcelains specifically designed for reduced layer thicknesses that allows users to focus on imitating the characteristics of enamel. A high-quality example is CERABIEN™ MiLai (Kuraray Noritake Dental Inc.). Consisting of a set of internal stains and porcelains with a firing temperature of just 740 °C and a coefficient of thermal expansion in the range of 9.5~11.0×10-6/K (50 °C – 500 °C), this product works well on lithium disilicate and zirconia.

Its aesthetic potential is surprisingly high: Depending on case-specific requirements, users are given the choice between maximum efficiency using a single-bake technique and maximum aesthetics achieved with more complex layering. The latter option is demonstrated below using the example of six maxillary anterior veneers.

Fig. 1. Lithium disilicate frameworks (Amber Press) on the model.

Fig. 2. CERABIEN™ MiLai Value Liner 1 applied to the framework. This porcelain is typically used on lithium disilicate for wash baking.

Fig. 3. First build-up with CERABIEN™ MiLai CCV2 in the cervical section, …

Fig. 4. … Value Liner 2, …

Fig. 5. … Creamy Enamel in the middle area …

Fig. 6. … and Tx used to add ultimate translucency.

Fig. 7. Appearance of the restorations after the first bake.

Fig. 8. Outcome of the internal staining procedure.

Fig. 9. Application of CERABIEN™ MiLai LT1 for a standard translucency and opalescence effect, …

Fig. 10. … E2, …

Fig. 11. … a mixture of E2 and ELT1 (mixing ratio: 50:50) for translucency and brightness and along the marginal ridges, …

Fig. 12. … Tx mixed with Royal Blue (mixing ratio 70:30) for a blueish translucency in the incisal area…

Fig. 13. … as well as a final layer of LTx to add ultimate translucency and opalescence to the whole enamel surface.

Fig. 14. Outcome of the third bake.

Fig. 15. Cutback for the final layer of porcelain.

Fig. 16. Final layer of CERABIEN™ MiLai added to the central and lateral incisors for translucency.

Fig. 17. Situation after the fourth bake, grinding and use of a rubber polisher.

Fig. 18. Outcome of the fifth bake (self-glaze).

Fig. 19. Beauty shots …

Fig. 20. … of the restorations …

Fig. 21. … on the model.

TRULY BEAUTIFUL OUTCOMES POSSIBLE

This case example reveals that CERABIEN™ MiLai is much more than just a maximum-efficiency solution: With the current line-up of porcelains and internal stains, truly beautiful restorations can be produced. Hence, users are given high flexibility regarding not only the high-strength framework material they prefer, but also the effort and time they would like to invest. This makes CERABIEN™ MiLai a versatile porcelain system that meets many needs and covers a wide range of applications in the dental laboratory.

Case by Andreas Chatzimpatzakis

When dental technicians from all over the world started using the micro-layering technique, they simply combined a reduced number of porcelains and stains from their original porcelain system. After some time, porcelains specifically designed for micro-layering were introduced to the dental market. Consequently, early adopters had to decide whether or not to switch to one of those new systems.

For me as a frequent user of CERABIEN™ ZR (Kuraray Noritake Dental Inc.), a porcelain system based on synthetic feldspathic porcelain developed for porcelain layering on zirconia frameworks, switching to any micro layering porcelain system was not an option. However, when I had the chance to test the brand-new CERABIEN™ MiLai porcelains and internal stains (Kuraray Noritake Dental Inc.), I grabbed it for two reasons. Firstly, the simplicity! I was surprised how easily I could achieve a high aesthetic result without using too many different ceramic powders. Secondly with this system, I have a micro-layering porcelain system at my disposal that works for both, zirconia and lithium disilicate. Farther more, the product is well-aligned to CERABIEN™ ZR – and offers a very similar handling.

CASE EXAMPLE

The following case is a nice example of how it may be used in the anterior region. The male patient had already been treated with monolithic zirconia crowns from another dental laboratory in the posterior region. Now, he desired a maxillary anterior smile makeover due to discoloured composite restorations and signs of tooth wear. The decision was made to produce six veneers with frameworks made of lithium disilicate (Amber Press), individualized with CERABIEN™ MiLai using the micro-layering technique. I would like to thank the prosthodontist Dr Konstantina Aggelara for the excellent collaboration and the intra oral photos.

For layering, I simply applied CERABIEN™ MiLai Value Liner 1. Then, I used CCV2 in the cervical and Tx in the incisal area, as well as Liner 2 for the mamelons. Internal stains were applied after the first bake. Subsequently, the canines were completed with LT1. The lateral and central incisors were built up with LT1 in the cervical area, Creamy Enamel on the marginal ridges and the middle and E2 mixed with Tx in the ratio 70/30 in the incisal area.

Fig. 1. Initial situation: The patient was unhappy with his lip line and facial appearance, …

Fig. 2. … particularly due to discoloured composite restorations and severe wear in the maxillary anterior region.

Fig. 3. Shade determination after tooth preparation.

Fig. 4. Restorations produced with Amper Press (Shade LT A2), individualized with CERABIEN™ MiLai.

Fig. 5. Lateral view: The internal play of colours (internal stains) creates a nice effect. Natural shading and surface texture.

FINAL SITUATION

Fig. 6a and 6b. Restorations placed in the patient’s mouth.

THE PERFECT COMPLEMENT TO MY STANDARD PORCELAIN SYSTEM

As hoped, CERABIEN™ MiLai offers similarly great handling properties as CERABIEN™ ZR – probably mainly due to the fact that it is also based on synthetic feldspathic ceramic. It is not only responsible for consistent handling, but also for predictable optical properties, eliminating unwanted shadow effects. As the system is designed for micro-layering, it offers a natural appearance when applied in thin layers. This fact – in addition to the broader compatibility (to high-strength oxide and silicate ceramics) – makes it worthwhile to consider using a specific porcelain system for micro-layering. Experience shows that it works just as well on zirconia as it does on lithium disilicate, so that combining both framework materials in a single patient becomes a lot easier, while the line-up is neat.

Case by MDT Andreas Chatzimpatzakis

EFFECTIVE FINISHING OF A ZIRCONIA FRAMEWORK WITH CERABIEN™ MiLai

‘Modern concepts are based on the smart combination of different materials.’

The implant-prosthetic restoration of edentulous jaws requires more than functional stability. Modern concepts are based on the smart combination of different materials. In the presented case, a titanium bar provides for a stable connection between the implants, while a zirconia framework offers the necessary strength and fracture resistance. Both materials stand out due to their high biocompatibility, the good soft tissue attachment properties of zirconia being particularly noteworthy. The real challenge in the selected type of restoration, however, begins with aesthetic realization. Micro-layering techniques promise efficiency combined with aesthetics – but this often comes with compromises, e.g. in terms of handling. With CERABIEN™ MiLai (Kuraray Noritake Dental Inc.), a new path is now being taken here.

MDT Andreas Chatzimpatzakis, Athens

The rapid development of all-ceramic framework materials such as zirconia and lithium disilicate calls for new veneering concepts. CERABIEN™ MiLai (Kuraray Noritake Dental inc.) picks up on the strengths of classic powder ceramics and optimizes them for the requirements of micro-layering – the reinterpretation of a classic, so to speak. The basis for this is provided by synthetic feldspathic ceramic technology, in which Kuraray Noritake Dental Inc. has decades of experience. The company developed its first synthetic dental ceramics back in the late 1980s – expertise that is now also used in the low-fusing porcelain system CERABIEN™ MiLai for micro-layering. Unlike natural feldspathic ceramics, the synthetic version provides for consistent properties without the need to adjust the formulation due to altering raw materials. This is reflected in stable coefficients of thermal expansion and a uniform particle distribution; prerequisites for aesthetic results and colour stability. Another decisive advantage is evident during the firing process: the special composition prevents micro-movements in the material during firing, which can lead to inhomogeneities and gray haze effects with conventional ceramics. This property is indispensable for micro-layering, as any irregularity, no matter how small, would be immediately visible in the thin ceramic layers.

INITIAL SITUATION

The presented case illustrates the technical procedure around the restoration of an edentulous maxilla. The prosthetic work was produced after the placement of six implants and their osseointegration. In consultation between the practice team around prosthodontist Dr Georgios Siavikis, laboratory technician and patient, the decision was made to restore the teeth with a bar-supported bridge construction. A CAD/CAM-fabricated titanium bar (Atlantis® BridgeBase, Dentsply Sirona) formed the basis. Due to its high manufacturing precision, it would provide for a passive fit of the reconstruction on the implants. The material of choice for the superstructure was zirconia, which was to be finalized using micro-layering due to the patient’s high aesthetic demands.

Fig. 1. Computer-aided design of the implant bar.

Fig. 2. Computer-aided design of the zirconia framework – transparent view revealing the BridgeBase.

Fig. 3. Computer-aided design of the zirconia superstructure.

WHY CHOOSE MICRO-LAYERING?

The decision to opt for micro-layering is based on tangible benefits: In addition to economic efficiency, the thin layer of porcelain provides a high level of safety and significantly reduces the risk of chipping. In addition, the ultra-thin porcelain layer enables a controlled approach to porcelain layering. However, we must be aware that with micro layering, around 80 to 90 percent of the restoration’s final shape is already created in the framework. Although this leads to maximum control during layering, it also places high demands on the selected framework material. With porcelain layer thicknesses in the micro range, the zirconia needs to be convincing in terms of aesthetics and mechanical strength. For our long-span bridge construction, we chose KATANA™ Zirconia HTML Plus (Kuraray Noritake Dental Inc.), a material that combines high strength with natural translucency. We deliberately opted for a disc in the shade A2 – one shade lighter than the desired target shade A3. This strategic choice enabled us to play with the colours during layering and implementation of the internal stain technique.

Fig. 4. Multi-Layered zirconia with a high strength and translucency used as a framework material.

WHY OPT FOR INTERNAL STAINING?

The internal stain technique is no longer an insider tip, but is one of the supreme all-ceramic disciplines. Kuraray Noritake Dental Inc. has perfected the technique over decades together with dental technicians. We particularly value the technique in our day-to-day laboratory work, as it gives restorations an individual touch that sets them apart from standard work. Unlike superficial stains, the internal staining creates a characterization from inside the restoration with a lively play of colours that unfolds naturally in changing light conditions.

Until now, it has been challenging to combine the advantages of the internal stain technique with those of micro-layering. Although we have put various approaches to a test and detected solutions that do work, we have always come up against technical limitations. The combination of both techniques – micro-layering and internal staining – places special demands on the porcelain system: It needs to allow characterization from the inside and at the same time be able to be processed in ultra-thin layers. CERABIEN™ MiLai closes the previous gap. As a low-fusing porcelain system, it combines the advantages of the internal stain technique with the efficiency of micro-layering. Being a powder-based porcelain system, the product may be used in the familiar way – only much more efficiently. The possibility of adjusting the consistency to individual needs gives us the precise control we need for minimal layer thicknesses. With 16 porcelains and 15 internal stains, the system remains manageable without compromising on design.

Fig. 5. The low-fusing porcelain CERABIEN™ MiLai is designed for micro-layering on zirconia and lithium disilicate.

FRAMEWORK PREPARATION

After milling and sintering, the framework in its cut-back design was processed systematically: The first step was to treat the zirconia surface with a diamond bur – under water cooling to avoid microcracks. In this phase, it is also possible to incorporate fine anatomical details such as mamelon structures or marginal ridges. To provide for a strong bond, the surface of the framework was then sandblasted with 50 μm alumina particles. In this context, it is important to apply a moderate pressure that conditions the surface without weakening the structure. Framework preparation was completed with ultrasonic cleaning for ten minutes. All this created the basis for a reliable bond between the framework and the veneering porcelain.

Fig. 6. Zirconia framework prepared for finishing.

INTERNAL STAINING MEETS MICRO-LAYERING

Next on the list was internal staining. It is often the smallest details that have the biggest effect – be it a prominent marginal ridge or an intensive cervical colouration. Sometimes, however, less is more. It is often a question of the dental technician’s artistic sensitivity and – of course – the individual situation. In this case, Tissue Red was used for a vivid effect of the gingival areas, while a combination of Cervical 2, Incisal Blue 1 and Mamelon 2 was chosen to give the teeth a three-dimensional depth effect. Subsequent micro-layering was carried out selectively: CCV2 in the cervical area, Creamy Enamel for lighter margins and LT1 for the desired standard translucency and opalescence. The gingiva was given its natural depth through a sophisticated interplay of shades and shapes – with a base of Tissue 1 and 5, while the keratinized areas were given their characteristic appearance with a 60/40 mixture of Tissue 1 and TX.

Fig. 7. Internal staining: Targeted application of the stains on the framework as the basis for the three-dimensional colour effect of the restoration.

Fig. 8. Micro-layering: Ultra-thin layering on the characterized framework gives the restoration its final shape and light dynamics.

What followed was the first bake. CERABIEN™ MiLai is a low-fusing porcelain. Its firing temperature of 740 °C is not only the enabler of its compatibility with various framework materials (zirconia, lithium disilicate), but also reduces the risk of distortion or micromovements causing unwanted changes in shape during repeated firings. Minor shape corrections were made after the first bake. In this step, a particular advantage of powder ceramics in micro-layering becomes apparent: they allow for precise modelling of even the finest structures and textures. The surface structure with its lively textures gives the work its natural appearance. The final glaze firing leveraged the self-glazing effect of CERABIEN™ MiLai.

Fig. 9. Occlusal view of the finished restoration.

Fig. 10. Clearly visible internal colour characteristics.

Fig. 11. Lively surface structure with interplay of concave and convex areas both in the area of the teeth and the gingiva.

Fig. 12. Restoration in situ; edentulous maxilla with an implant-based zirconia bridge. The patient’s wishes regarding individual aesthetics are fulfilled thanks to internal staining and micro-layering (CERABIEN™ MiLai) – effectively, economically and safely.

EFFECTIVE AND FLEXIBLE

In the case presented, we combined the internal stain technique with micro-layering to fulfil the patient’s individual aesthetic demands. However, CERABIEN™ MiLai is just as suitable for micro layering without internal staining – fast, straightforward and effective. And this is precisely the advantage of this system: it offers the flexibility to go your own way – tailored to the respective situation and to the framework material (zirconia and lithium disilicate), eliminating the need to store different porcelain systems. Particularly useful: CERABIEN™ MiLai can be combined with the tried-and-tested CERABIEN™ ZR porcelain. Thanks to the low firing temperature, areas that have already been layered remain stable in shape and colour. The high versatility makes CERABIEN™ MiLai our preferred system for effective micro-layering. MiLai YOUR WAY – we have found our way with it and know that we have the right solution for every case.

‘THE HIGH VERSATILITY MAKES CERABIEN™ MILAI OUR PREFERRED SYSTEM FOR EFFECTIVE MICRO-LAYERING.’

Case by Andreas Chatzimpatzakis

PUTTING CERABIEN™ MiLai TO THE TEST

Nowadays, lithium disilicate and highly translucent variants of zirconia are among the most popular ceramic materials processed in the dental laboratory. Their favourable optical properties allow us to opt for simplified finishing approaches such as micro-layering in a great majority of cases. For dental technicians, this means a reduction of the manual workload without compromising the quality of the outcomes.

Recently, Kuraray Noritake Dental Inc. has launched a new set of porcelains and internal stains specifically developed for micro-layering, which works not only with zirconia but also with lithium disilicate. The CERABIEN™ MiLai line-up consists of 16 porcelains and 15 internal stains, which – the manufacturer claims – are easy to select and manage. As the more universal approach with a single porcelain for silicate ceramics and zirconia enables us to streamline inventory management and to standardize layering procedures, we decided to test the new product in the laboratory setting. The following case is a documentation of the first try of CERABIEN™ MiLai on lithium disilicate (Amber Press, HASS Bio).

Fig. 1. Anatomically reduced crown structures made of lithium disilicate (Amber Press LT, shade A2).

Fig. 2. Crowns after the application of CERABIEN™ MiLai Value Liner 1 generally used to increase the value of lithium disilicate restorations, followed by wash firing.

Fig. 3. Situation after CERABIEN™ MiLai Internal Stains: A+ is applied in the cervical area to enhance the chroma, and Mamelon Orange 2 alternating with Incisal Blue 1 are used to imitate the mamelon structures in the incisal area.

Fig. 4. Crowns after the first and second bake with CERABIEN™ MiLai Porcelain LT1 applied in the cervical area to add translucency and opalescence to the enamel, E2 mixed with ELT (ratio: 60/40) to optimize the body area and LTx to boost the incisal translucency and opalescence.

Fig. 5. Restorations finalized with CERABIEN™ ZR FC Paste Stain Clear Glaze and external stains to add some lines incisally.

Fig. 6. Lateral view of the restorations.

Fig. 7. Natural translucency and internal optical structure revealed in transmitted light.

CONCLUSION

The outcome achieved at the first go with the CERABIEN™ MiLai line-up for micro-layering on lithium disilicate is very satisfying. I feel that we can achieve great results with this system, which is indeed easy to select and manage. The reduced number of shades clearly comes in handy especially for beginners, who will be grateful for the option of creating lifelike restorations with fewer decisions to be made, and less effort involved compared to conventional ceramic line-ups. The possibility of standardizing and streamlining procedures by using a single porcelain system for all micro-layering procedures is likely to improve the life of every dental technician.

Case by Andreas Chatzimpatzakis

With CERABIEN™ ZR, Kuraray Noritake Dental Inc. offers a whole porcelain portfolio for the finishing of restorations based on zirconia. Originally developed for complex layering techniques, the synthetic feldspathic porcelain powders, liquid ceramics, internal and external stains allow for the creation of beautiful dental artwork. We love to work with the system as it offers consistent handling and mechanical properties, allowing us to produce predictable outcomes.

However, the complexity of the system with its huge number of different shades can pose challenges to less experienced users. This complexity is further increased when different substructure materials are used, as CERABIEN™ ZR works exclusively on zirconia, so that users would need to select and manage a second porcelain system when opting for a lithium disilicate framework, for example.

For dental technicians who would like to keep it smartly simple, the new CERABIEN™ MiLai line-up is certainly a great solution. Specifically developed for micro-layering on pre-shaded, highly translucent substructure materials such as lithium disilicate or a latest-generation zirconia, CERABIEN™ MiLai porcelains and internal stains may be applied in a thin (micro-) layer on restorations with a small (vestibular) cut-back. Just like CERABIEN™ ZR, the new system is based on synthetic feldspathic porcelain delivering consistent properties, but the line-up is reduced to 15 internal stains and 16 porcelains. As the CERABIEN™ MiLai has a firing temperature of 740 °C (1,364 °F), it works on oxide ceramics like zirconia, but also on reinforced silicate ceramics like lithium disilicate*.

*The material should have CTE value within 9.5~11.0×10^-6 /K (50~500 °C)

Consequently, the system may be used as the universal porcelain system for micro-layering on aesthetic ceramics. With its slim portfolio, it fits the philosophy of creating impressive restorations with fewer components, layers and bakes very well, as demonstrated in two different case examples below.

VENEERS BASED ON LITHIUM DISILICATE

Fig. 1. Six anterior veneers made of lithium disilicate (Amber Press LTA2 HASS Bio), designed with a slight cut-back to create the space needed for micro-layering.

Fig. 2. Restorations after the application of CERABIEN™ MiLai Value Liner 1 followed by wash firing and internal staining. This type of porcelain increases the value of lithium disilicate restorations. By staining the core, we control the chroma and add some internal characteristic effects. In this case, we added Cervical 2 to the marginal area and characterized the incisal third with Cervical 2 and Incisal Blue 1 & 2.

Fig. 3. First porcelain layer consisting of CERABIEN™ MiLai LT1 applied to the cervical, ELT1 to the mesial third and TX to the incisal third before …

Fig. 4. … and after the first bake.

Fig. 5. Application of internal stains for special effects like cracks, intense chroma etc.

Fig. 6. Second porcelain layer consisting of CERABIEN™ MiLai LT1 applied to the canines as well as the cervical third of the central and lateral incisors, while the middle and incisal third of the four incisors is individualised with LTx.

Fig. 7. Finished restorations on the master cast.

Fig. 8. Lateral view of the restorations highlighting their natural surface texture.

ANTERIOR BRIDGEWORK BASED ON ZIRCONIA

Fig. 1. KATANA™ Zirconia HTML Plus (A2 shade) structure immediately after milling.

Fig. 2. Appearance of the substructure after sintering.

Fig. 3. High translucency of the zirconia with the applied CERABIEN™ MiLai stains and porcelains on teeth and gingiva.

Fig. 4. Palatal view of the individualized restoration before the firing process.

Fig. 5. Restoration ready for try-in.

CONCLUSION

The two different cases confirm that CERABIEN™ MiLai works very well on lithium disilicate and zirconia. Despite the reduced number of stains and shades, it is possible to imitate most of the shades and individual effects found in natural teeth, which are important for lifelike outcomes. Hence, the new material is worth a try for everyone who prefers standardized and simplified procedures.

Cases by DT Ioulianos Moustakis and MDT Andreas Chatzimpatzakis

Producing dental restorations that are not recognizable as such – this is probably the ultimate goal of every dental technician. For a long time, pursuing this goal was complicated by core materials whose optical properties were very different from those of natural teeth. The dark metal or opaque zirconia substructures had to be masked by applying multiple layers of intensively coloured ceramic powders, topped by more translucent porcelains imitating the enamel.

The rise of modern, tooth-coloured core materials such as lithium disilicate and zirconia has changed the game. With a core that is highly aesthetic, translucent and close to the final shade, it became much easier to produce a restoration that is virtually indistinguishable from the adjacent teeth. The thickness of the porcelain layer decreased as did the number of shades to be combined and necessary bakes to be conducted. The use of the existing porcelain systems for the new micro-layering techniques posed several new challenges: those systems originally developed for opaque zirconia were indicated for the more translucent zirconia core materials, but usually not for lithium disilicate. Moreover, the complexity of the systems made their use unnecessarily complicated for inexperienced users.

Consequently, Kuraray Noritake Dental Inc. developed a new porcelain system for micro layering on zirconia and lithium disilicate core materials. The portfolio of CERABIEN™ MiLai, which refers to micro-layering and the Japanese word for future (mirai), consists of 15 internal stains (13 tooth colours including Bright to boost the translucent and Fluoro to boost the fluorescent effect, and two tissue colours) and 16 porcelains (12 tooth porcelains and four tissue porcelains). Hence, it enables dental technicians to implement a modernized version of the original Internal Live Stain Technique developed by Hitoshi Aoshima in the early 1990s in a porcelain layer of minimal thickness.

The following demo cases are used to show how to achieve lifelike aesthetic restorations based on aesthetic zirconia and on lithium disilicate. Illustrating each step, the cases allow users to anticipate how much time and effort can be saved compared to traditional layering techniques.

CASE 1

MAXIMALLY SIMPLE APPROACH ON LITHIUM DISILICATE

In this case, the idea was to restore the six maxillary anterior teeth in a simple way. The selected core material for the planned veneers was Amber Press (HASS Bio) LT in the shade B1. The lithium disilicate restorations were pressed with a micro cut-back and their fit was checked on the model, followed by surface texturing, sandblasting and steam cleaning [Fig. 1a]. When the veneers are milled instead of pressed, the procedure is the same. After that, the restorations are ready for the application of the CERABIEN™ MiLai internal stains for characterization of the core. In order to achieve the desired result, it is critical to mix the selected stains with the internal stain Bright responsible for a translucent effect. The chroma map for internal staining is shown in figure 1b, the outcome of the procedure in figure 1c. Subsequently, the veneers were built up to their final anatomy with selected CERABIEN™ MiLai Porcelains [Fig. 1d] to imitate the enamel and create a window effect. In this approach, simple layering and a single bake are sufficient to create the desired restoration. After glazing with Clear Glaze, finishing of the restorations was accomplished with paper-abrasive cones, a rubber polisher and polishing paste. The outcome is shown in figure 1e.

Fig. 1a. Pressed lithium disilicate veneers after surface optimization (grinding), sandblasting and steam cleaning on the model.

Fig. 1b. Chroma map for the application of CERABIEN™ MiLai Internal Stains to the lithium disilicate surface. We selected B+ (red colour) for the cervical area. For the proximal and middle incisal areas, Incisal Blue 1 & 2 (gradient blue colour) were applied and incisally in the middle, we chose Cervical 2 (orange colour). Tip: all internal stains were mixed with Bright and IS Liquid.

Fig. 1c. Appearance of the veneers after the application of CERABIEN™ MiLai Internal Stains.

Fig. 1d. CERABIEN™ MiLai Porcelains applied on top of the internal stains: LT1 is used for the cervical area (red) and a mixture of TX and E2 (30:70 ratio) for the middle and the incisal third.

Fig. 1e. The final restorations after glazing with Clear Glaze and mechanical polishing using paper-abrasive cones, a rubber polisher and Pearl Surface Z (Kuraray Noritake Dental Inc.).

Images courtesy of Andreas Chatzimpatzakis.

CASE 2

ADVANCED APPROACH ON LITHIUM DISILICATE

In order to imitate a more complex inner colour structure with mamelons, different levels of translucency and more individual effects, a slightly more complex micro-layering approach was selected. Again, the core was produced using Amber Press in the LT variant and the shade B1. After pressing and fitting on the model, we reduced the incisal third to create space for the transparent porcelain [Fig. 2a]. Subsequently, an extremely thin layer of CERABIEN™ MiLai Porcelain adding translucency to the enamel surface (TX) was applied in the incisal third of the veneers [Fig. 2b]. In this way, it is possible to create an optimally translucent basis for the application of the internal stains. The first bake was conducted and the surfaces were sandblasted as well as steam cleaned to create the conditions needed for internal staining [Figs. 2c and 2d]. The chroma map for and outcome of the internal stain application are shown in figures 2e and 2f. Afterwards, a final layer of CERABIEN™ MiLai Porcelain was applied [Fig. 2g]. All four incisors received a layer of LTx to add ultimate translucency and opalescence to the enamel, while LT1 was the material of choice in the cervical third of the canines, where LTx completed the layer in the other areas. As LT1 is slightly less translucent and opalescent, a natural effect is obtained in this way. The outcome obtained after glazing and mechanical polishing is shown in Figure 2h.

Fig. 2a. Lithium disilicate veneers reduced for the advanced layering procedure involving more porcelains and bakes.

Fig. 2b. Thin layer of TX applied to the incisal third of the restorations to boost the translucency in this area.

Fig. 2c. Appearance of the veneers after the first bake.

Fig. 2d. Ceramic surfaces after sandblasting and steam cleaning.

Fig. 2e. Chroma map for the application of the internal stains. Cervical 2 was used for the cervical third, Incisal Blue 2 for the proximal regions and Mamelon Orange 2 for the mamelons. As mentioned before, the selected internal stains were mixed with Bright.

Fig. 2f. Appearance of the veneers after the bake of the applied CERABIEN™ MiLai Internal Stains.

Fig. 2g. Final build-up to reach the desired shape of the veneers. LTx is the only material applied to the central and lateral incisors, while the canines are built up with LTx in the incisal and middle and LT1 in the cervical third.

Fig. 2h. Glazed and polished veneers on the model.

Images courtesy of Andreas Chatzimpatzakis.

CASE 3

ADVANCED APPROACH WITH GUM AREAS ON ZIRCONIA

In this case, a highly complex ten-unit bridge with gum parts in the anterior region had to be produced. The selected framework material was KATANA™ Zirconia HTML Plus (Kuraray Noritake Dental Inc.), which offers a multi-layered colour structure, an optimized translucency and the high flexural strength required for long-span bridges. The restoration was milled in an anatomically reduced design and the surface texture was optimized with rotating instruments before sintering [Fig. 3a]. After the final sintering procedure, the restoration had a favourably high translucency in the incisal region and a natural shade structure [Figs. 3b and 3c]. In the first step of the micro-layering procedure, the application of the CERABIEN™ MiLai Internal Stains was planned and carried out [Figs. 3d and 3e]. Subsequently, different layers of CERABIEN™ MiLai Porcelain were applied. The images 3f to 3h reveal which shades were combined and illustrate the procedure, while the outcome before and after the last bake is shown in Figures 3i to 3k. In the next step, the gum areas were completed using the CERABIEN™ MiLai tissue porcelains Tissue 4, 5 and 6 in the order and locations described in Figures 3l to 3o. In the final layer, Tissue 1 was mixed with ELT1 to imitate the labial frenulum and with LTx to create a smooth transition to the natural gingiva [Figs. 3p and 3q]. The final restoration is shown in Figure 3r.

Fig. 3a. Milled restoration after surface texturing.

Fig. 3b. Shade and translucency of the sintered zirconia restoration.

Fig. 3c. Highly translucent bridge on the model.

Fig. 3d. Chroma map for the application of CERABIEN™ MiLai Internal Stains.

Fig. 3e. Applying a mixture of Bright, Salmon Pink and Tissue Pink to the gum area.

Fig. 3f. Application of CERABIEN™ MiLai E2 to add translucency to the structure.

Fig. 3g. Application of Tx and a mixture of Tx and CCV-2 to individualize the cervical and incisal areas while boosting the translucency of the enamel in the middle and incisal third.

Fig. 3h. Adding a final layer of LT1 for additional translucency and opalescence.

Fig. 3i. Appearance of the ten-unit bridge before the bake – labial view.

Fig. 3j. Appearance of the ten-unit bridge before the bake – palatal view.

Fig. 3k. Appearance of the ten-unit bridge after the bake.

Fig. 3l. Application of small amounts of Tissue 5 …

Fig. 3m. … covered with a layer of Tissue 6 alternating with Tissue 5.

Fig. 3n. Following another bake, Tissue 5 is applied in the proximal areas.

Fig. 3o. How to combine Tissue 6 and Tissue 4 in the next layer.

Fig. 3p. How to complete the tissue layer with Tissue 1, locally mixed with ELT1 or LTx.

Fig. 3q. Restoration before the final bake.

Fig. 3r. Final ten-unit bridge ready for placement.

Images courtesy of Ioulianos Moustakis.

Article first published in Labline Magazine Issue 45, Spring 2022 edition.

Case by Andreas Chatzimpatzakis

Observe and copy: This is the key to nature-like dental restorations. There are many optical effects, colour transitions and morphological details in natural teeth that need to be taken in and understood – and replicating them is only possible for those who know exactly how their materials work. Once these skills are acquired, however, they enable a dental technician to produce their restorations as truly beautiful copies of nature. Even when restoring a single maxillary central incisor, the technique delivers outstanding – or inconspicuous - outcomes, as revealed by the following example.

Using high-quality, translucent and gradient-shaded zirconia frameworks and porcelains, the layering technique does not have to be highly complicated. Two bakes and a number of selected effect liquids, internal stains and porcelains are usually sufficient for outcomes that exceed expectations.

CASE EXAMPLE

In the present case, a young male patient had a quite opaque crown on his maxillary right central incisor that needed to be replaced. During shade selection in the dental laboratory (Fig. 1), it was observed that the cervical third of the adjacent central incisor is lighter than the rest. Its shade in other areas corresponded to B4 on the VITA classical A1-D4^® Shade Guide. Hence, it was decided to use a somewhat lighter material for the framework and darken the restoration especially in the middle and incisal areas with internal stains.

The concrete plan was to mill a coping made of KATANA™ Zirconia STML (Kuraray Noritake Dental Inc.) in the shade A3, characterize it with Esthetic Colorant (both Kuraray Noritake Dental Inc.) and sinter the piece (Figs 2 to 4). In the following layering procedure including just two bakes, a combination of internal stains and selected porcelains (CERABIEN™ ZR, Kuraray Noritake Dental Inc.) was applied as illustrated in Figures 5 to 12. Figures 13 to 17 display the result on the model, minor adjustments during try-in and the final treatment outcome.

Fig. 1. Shade selection. The cervical third of the adjacent central incisor is lighter than usual compared to the middle and incisal areas.

Fig. 2. Coping made of KATANA™ Zirconia STML in the shade A3.

Fig. 3. Intensification of some shade characteristics of the multi-layered blank using Esthetic Colorant in the shades Grey (middle) and Blue and Grey (incisal area).

Fig. 4. Coping after sintering.

Fig. 5. Colour map for internal staining, using CERABIEN™ ZR Internal Stains.

Fig. 6. Result of the use of Shade Base Stain Modifier Fluoro to increase the fluorescence and internal staining as planned.

Fig. 7. Application of Opacious Body OBA2, …

Fig. 8. … Translucent Tx …

Fig. 9.: … and Luster CCV-2.

Fig. 10. Crown after the first bake.

Fig. 11. Crown after the application of CERABIEN™ ZR Internal Stains: A+, Aqua Blue 2, White mixed with Cervical 2 (ratio: 30/70) for the cracks, and Cervical 2.

Fig. 12. Application of Luster LT1 to finalize the shape.

Fig. 13. Finished crown after the second bake on the model.

Fig. 14. Evaluation of the surface texture: Observing and copying the surface details is as important as the imitation of the shade characteristics.

Fig. 15. Minor texture adjustments during try-in.

Fig. 16. Final restoration in place after cementation with PANAVIA™ V5 (Kuraray Noritake Dental Inc.).

Fig. 17. Treatment outcome.

CONCLUSION

Mastering the art of observing natural teeth is the key to lifelike restorations. It allows a dental technician to develop a deep understanding of shade and morphology, which is – apart from knowing the selected materials very well – the only talent needed to reach a high level of excellence. Those who are observant and take in every detail with their eyes can be sure that their mind will understand and their hands will automatically follow.