429 Too Many Requests

Case by Kostia Vyshamirski, DT

KATANA™ Zirconia YML AND CERABIEN™ MiLai

Virtually every patient in need of restorative treatment desires functional restorations with an aesthetic appearance. However, the individual expectations and needs may be very different depending on the clinical situation (state of the natural tooth structure, parafunctional behaviour, periodontal health etc.), the patient’s financial resources and personal preferences. A versatile material combination fulfilling many different needs and desires is KATANA™ Zirconia YML finished using micro-layering with the new CERABIEN™ MiLai (both Kuraray Noritake Dental Inc.).

This system supports low invasive preparations due to a favourable minimum wall thickness of the merely monolithic multi-layered zirconium oxide prosthesis and a minimal thickness of the porcelain layer in the aesthetic zone. Moreover, the high strength zirconium oxide prosthesis combined with only a very thin layer of porcelains makes this technique extremely useful in patients with parafunctional habits like bruxism. Last but not least, consisting of a carefully compiled selection of internal stains and porcelain shades, CERABIEN™ MiLai supports the creation of individual 3D shade effects that mimic those of natural teeth even when space is limited. The following case example reveals how this is possible.

INITIAL SITUATION

The patient presented with concerns related to both function and appearance. During the diagnostic phase, it was determined that increasing the vertical dimension of occlusion (VDO) and creating a wax-up in the new jaw position would be necessary to improve both the occlusion and the aesthetic appearance of the smile.

Fig. 1. Intraoral scan of the maxillary teeth revealing severe tooth wear.

Fig. 2. Intraoral scan of both jaws confirming the need for an increase of the VDO.

Fig. 3. Intraoral scan: Occlusal view of the maxillary teeth.

TREATMENT PLANNING AND COMPUTER-AIDED DESIGN

Following the approval of the wax-up, the treatment plan was created. It consisted of restoring the four anterior incisors with zirconia crowns and performing direct composite restorations on the posterior and lower teeth. To conserve as much of the healthy tooth structure as possible, the space created was aligned to the required wall thickness of the planned restoration (framework + micro-layer of porcelain in the vestibular areas only). Following an aesthetic analysis, the crowns were designed with a minimal vestibular cutback. This was due to the patient’s functional problems, which would increase the chipping risk in case of using a more heavy cutback design with a thicker, more conventional porcelain layer. KATANA™ Zirconia YML offers exceptional aesthetics, requiring only a 0.3 mm reduction for the porcelain to achieve natural results. Therefore, it was the logical material choice for this specific case.

Fig. 4. Minimally invasive preparations for the crowns.

Fig. 5. Occlusal view of the preparations.

Fig. 6. Aesthetic analysis – a crucial step for achieving the desired new smile.

Fig. 7. Frontal view of the crowns in their final cutback design.

Fig. 8. Lateral view of the crowns in the CAD software.

CROWN PRODUCTION

Immediately after milling, the zirconia surface was treated with effect liquids. This kind of pre-sintered characterization helps enhance the characteristics of zirconia restorations. In the presented case, orange stain was applied to the cervical area, while a blue stain was used at the incisal edge. In addition, a white opaque liquid was applied to the inner surface of the central zirconia crowns to block out any discolouration from the underlying tooth structure. Following final sintering, the vestibular layer of porcelain was built up with CERABIEN™ MiLai using a combination of internal stains and porcelain micro-layering. After morphological adjustments and surface polishing, the restorations were completed by applying CERABIEN™ ZR FC Paste Stain and Glaze. Final polishing was then performed to enhance the natural appearance of the surfaces.

Fig. 9. Effect liquids applied to the cervical and incisal areas of the crowns.

Fig. 10. Treatment of the central incisor crowns’ inner surfaces.

Fig. 11. KATANA™ Zirconia YML framework after sintering.

Fig. 12. CERABIEN™ MiLai Internal Stains and Porcelains.

Fig. 13. Prepared vestibular surfaces ready for application of the internal stains.

Fig. 14. Application of 0.2-0.3 mm layers of CERABIEN™ MiLai porcelain: CCV2 for the cervical area, LT1 – Creamy Enamel for the main body and luster, LTX at the incisal edge.

Fig. 15. Frontal view of the final restorations on the model.

Fig. 16. Lateral view of the final restorations on the model.

Fig. 17. Polished and glazed palatal surfaces of the crowns.

FINAL OUTCOME

The finalized restorations showcase great details, crafted with CERABIEN™ MiLai internal stains and porcelains. The result are natural-looking restorations. An additional benefit of using zirconia as a restorative material is its excellent compatibility, which is evident in the healthy gingival conditions.

Fig. 18. Restorations in place.

Fig. 19. Natural-looking restorations in the patient’s mouth.

Dental Technician:

KOSTIA VYSHAMIRSKI

DT Kostia Vyshamirski, Riga, Latvia

After earning his Dental Technician Certificate from the Medical College in Minsk, Belarus, in 2014, Kostia began his career as a dental technician, focusing on aesthetic clinical cases that integrate the latest digital and manual technologies. Moving to Riga, Latvia, in 2015 greatly expanded his professional opportunities.

With over a decade of experience, Kanstantsin Vyshamirski now conducts courses, lectures, and seminars worldwide. He is a member of the DTG (Dental Technician Guild), a professional group of dental technicians based in the USA, and an invited guest of the AAED (American Academy of Esthetic Dentistry), an exclusive, invitation-only organization.

Operating his own lab in Riga, Latvia, Kanstantsin specializes in aesthetic prosthetic porcelain work and is an experienced, passionate user of KATANA™ Zirconia and Noritake porcelains.

Interview with Ghaith Alousi, DT

He inspires dental technicians with his passion and creativity as a course instructor, and with Nature Style, he has developed a well-conceived concept for the creation of lifelike anterior restorations. We are talking about Ghaith Alousi, a dental technician based in Wiesbaden, Germany. While course participants usually attend his training courses eager to learn from his experience and technical knowledge, they often return to their laboratories bursting with positive energy, truly inspired and deeply motivated to break new ground.

Ghaith Alousi, what is the dental technician’s primary mission?

In my eyes, dental technicians are not artists; rather, their primary mission is to replicate nature – both functionally and aesthetically. Every tooth, like every patient, is as unique as a fingerprint. To recreate a natural tooth as accurately as possible, we must listen, observe, and understand. To truly perceive the details that matter, however, we need to know where to focus our attention. In my opinion, the three golden keys to anterior aesthetics are paramount: balanced translucency and opacity, morphology, and surface texture.

What about colour?

While colour is undoubtedly a crucial aspect, I believe it is often overemphasized. Many dental technicians focused on aesthetic anterior restorations find themselves preoccupied solely with colour. However, natural teeth – the model we aim to replicate – embody far more than just a blend of hues.

First and foremost, we must understand how light interacts with teeth. They diffuse light in a unique manner, with different layers of enamel and dentin each possessing distinct optical properties. Additionally, the individual shape and surface texture of a tooth significantly affect the perceived attractiveness of a patient’s smile and overall facial appearance. Therefore, I have learned to prioritize these elements, observing nature closely and striving to comprehend what I see before embarking on the replication process.

Fig. 1. Light-optical properties of natural teeth imitated with KATANA™ Zirconia YML, Esthetic Colorant and CERABIEN™ ZR porcelain (Kuraray Noritake Dental Inc.).

Let’s take a brief look at each of the three golden keys, starting with the light-optical properties.

To truly grasp how light interacts with natural teeth, we must first examine their structure. Natural teeth consist of various layers, each displaying unique light-optical behaviours, with enamel and dentin being the most significant. Upon closely observing the dentin core of a tooth, we realize it is not only responsible for the tooth’s fundamental colour but also exhibits distinct opacity – it does not transmit light; instead, it reflects and absorbs it. In contrast, enamel presents a different scenario: its thickness varies with factors such as the patient’s age, but it is consistently highly translucent. This translucency allows a portion of light to pass through, with only a minimal amount reflected or absorbed.

Once we have a solid understanding of the natural light dynamics inherent in a patient’s teeth, the next step is to replicate these characteristics using selected materials. Thus, comprehending the light-optical properties of available materials, choosing them wisely, and applying them effectively are crucial milestones on the path to success.

What about morphology?

I firmly believe that mastering morphology – the replication of natural tooth shapes – can significantly impact a dental technician’s work. The growing popularity of carving workshops in Japan and other parts of the world reinforces this idea. Aspiring technicians avoid using standard dental libraries that produce generic smiles for their patients. Rather than traveling long distances to attend workshops and build our own mental library of tooth shapes, we can explore the intricacies of form and shape right in our dental laboratories through careful observation and consistent practice. Some technicians capture images of the teeth they encounter, while others concentrate on their own teeth or those of colleagues and patients. This approach allows for the replication of shapes using materials like wax or ceramics. By honing our observation and replication skills, we expand our personal knowledge base. This commitment to detail fosters true mastery – a continuous journey toward perfection.

Fig. 2. Example of a natural surface texture reproduced with CERABIEN™ MiLai and different diamond burs, stones and rubber polishers.

Is surface texture similarly important?

Absolutely. The surface texture of a restoration, even more than its hue, must precisely match that of surrounding or opposing teeth to achieve a natural appearance. To accomplish this, we must understand and replicate the intricate interplay of micro- and macrotextures that create a tooth’s natural look. Macrotexture encompasses the tooth’s overall surface characteristics, including varying concavities, convexities, line angles, and vertical V-shaped grooves. In contrast, microtexture focuses on finer details, such as growth lines (striae of Retzius), perikymata, small grooves, and the degree of surface gloss. A keen eye is essential to replicate every surface detail harmoniously so that light interacts optimally, creating reflections, shadows, and highlights exactly where they are needed.

Fig. 3. Large tooth created with CERABIEN™ ZR.

How do you practice?

To practice replicating surface texture and morphology, I typically start with enlarged model teeth, first using wax and later transitioning to my preferred dental materials and instruments. The increased size of the working base allows for easier detection, reproduction, and assessment of relevant morphology and surface details compared to original-sized tooth forms. This enlargement also facilitates the evaluation of light-optical properties. For the final assessment, I often apply silver or gold powder to the surface of the model tooth, which highlights even the finest surface nuances. This method makes it easy to identify areas that are well-executed and those that may need improvement.

Fig. 4. Gold powder applied to anterior restorations …

Once I achieve a high level of quality with the enlarged model teeth, I transfer the acquired skills to real-life applications by working with actual-sized teeth. This practice framework allows me to continuously enhance my basic skills. Moreover, each time I start working with a new instrument or material, this approach streamlines the initial learning curve, quickly elevating my performance to a high standard.

Fig. 5. … to evaluate their shape and surface texture.

What are your preferred material combinations for different indications / needs?

For cases with highest aesthetic demands, CERABIEN™ ZR (Kuraray Noritake Dental Inc.) is my favourite porcelain system. I This system can be utilized either as a standalone solution for producing veneers using the refractory die technique or in conjunction with a zirconia framework – typically crafted from KATANA™ Zirconia variants such as KATANA™ Zirconia UTML, STML, HTML Plus, or YML (also from Kuraray Noritake Dental Inc.) – in a full layering approach.

I frequently employ this combination to produce single crowns in the anterior region, selecting the framework material based on the colour of the underlying tooth structure and the appearance of adjacent teeth. An alternative approach is layering with CERABIEN™ MiLai, which consists of internal stains and porcelains compatible with zirconia and lithium disilicate. I prefer to combine this system with the previously mentioned zirconia variants or with lithium disilicate, predominantly using the porcelain to replicate enamel. Sometimes, I employ the system’s internal stains to enhance the result with natural colour effects.

Apart from observing closely, selecting appropriate materials and copying carefully, are there any additional factors decisive for great treatment outcomes from the technician’s point of view?

To my mind, there are two additional essential factors: Proper interaction and communication within the restorative team and personal interaction with the patient. Especially in the highest aesthetic demand cases, meeting a patient in person is very important. They are usually invited to visit the dental laboratory twice, prior to treatment planning and for try-in. Nothing can replace personal interaction with them and a genuine impression of the initial situation. After all, we need to give them a sense of security and build trust, while analysing their character, facial characteristics, skin colour and more allows us to produce perfectly matching restorations.

Fig. 6. Full layering approach with CERABIEN™ ZR on a KATANA™ Zirconia YML framework.

And the restorative team?

We share a common goal: to fulfil the desires of our patients. I firmly believe that achieving this requires a united effort from the entire team. Collaboration hinges on appreciative and open communication at all levels and demands absolute honesty. Furthermore, everyone involved must be committed to continuously developing their skills.

I hold high expectations not only for my own work but also for the contributions of each dentist in our team. After all, their work forms the foundation of what I do. For example, when a dentist invests in an intraoral scanner and starts providing digital records, it is my responsibility to verify whether the quality of those scans meets our high standards. If I notice that the quality could be improved, I approach the situation with respect, offering constructive feedback and guidance to help them deliver quality scans consistently. This is crucial, as high-quality scans are the prerequisite for creating outstanding restorations.

In my experience, most dental practitioners appreciate this kind of honest and supportive communication. It creates an environment where we can all grow and evolve together.

Do you have any additional comments?

Be authentic, strive for excellence, and approach each day as an exhilarating opportunity. Courage plays a vital role, too – the readiness to venture beyond your usual routines, such as experimenting with different shades to discover new possibilities, fosters growth. Even if the outcome does not meet your expectations, there is valuable insight to gain from the experience that can guide you in the future. To reach new horizons, be open to exploring uncharted paths.

Dentist:

GHAITH ALOUSI

Ghaith Alousi, born in 1994, successfully completed his training as a master dental technician in 2013 in Damascus, Syria, where he gained initial experience in a dental laboratory. From 2014 to 2016, he worked independently in Damascus, using his craftsmanship to produce ceramic work such as frameworks, veneers, crowns and bridges, and implant-based restorations. He also engaged in shade determination, photography, and CAD/CAM technology.

He came to Germany in 2016 and quickly felt at home. Through further education, he has continuously expanded his knowledge and skills and is currently working as a dental technician in Wiesbaden. To achieve the best possible results, Ghaith Alousi places great value on collaboration with dentists and personal contact with patients.

BUSTING MYTHS AROUND HIGH-STRENGTH CERAMICS IN DENTISTRY

Crowns, bridges, partial restorations: When it comes to replacing or restoring an individual’s teeth with fixed dental prostheses, the choice is often between the high-strength ceramics - lithium disilicate and zirconia. Originally, the higher aesthetic potential of silicate ceramics made them particularly suitable for single tooth restorations, while the high-strength option zirconia was predominantly used for bridges and frameworks. Due to continuous improvements in the development of dental ceramics and adhesive technology, things have changed. Many of the original limitations and restrictions are no longer valid, and new opportunities arise for users in the dental setting.

In the following, we will address certain persisting myths about the use of zirconia and lithium disilicate in dentistry. In this context, you will receive an update on what is possible with the materials today and guidance on how and when to use them.

1. ZIRCONIA IS AESTHETICALLY INFERIOR TO LITHIUM DISILICATE

The original zirconia used in dentistry was whitish-opaque. Therefore, it was used as a framework material only. To create aesthetic restorations, it was necessary to apply a relatively thick layer of veneering porcelain. More recent generations of zirconia, however, include variants with a particularly high translucency and a multi-layered colour structure. These variants allow for less complex finishing techniques such as micro-layering or external staining. KATANA™ Zirconia UTML (Kuraray Noritake Dental Inc.), for example, is one of the most translucent zirconia materials on the dental market. Depending on the test method used, it offers a similar or only somewhat lower translucency compared to lithium disilicate (IPS e.max CAD LT, Ivoclar Vivadent)^1-4. The desired natural result is achieved as light reaches – and reflects – the underlying tooth structure. Consequently, true-to-life restorations can be produced in an efficient, highly automated workflow.

CONCLUSION

Depending on the variant of zirconia and lithium disilicate used, both materials offer similar aesthetic properties, while even the highest-translucency zirconia is stronger than the highest-strength lithium disilicate available. Material selection may therefore be based on other criteria such as preparation depth for example.

2. ZIRCONIA-BASED RESTORATIONS ARE WEAKER THAN LITHIUM DISILICATE-BASED ONES DUE TO THE NEED OF A PORCELAIN LAYER ON TOP OF ZIRCONIA

This assumption is true for the first generations of dental zirconia. For modern zirconia materials with a high translucency and multi-layered colour structure, however, the situation is different. They are suitable for the production of monolithic restorations or restorations with a minimal (vestibular) cutback and a micro-layer of porcelain. With occlusal contact areas made of plain (polished or glazed) zirconia, these restorations are stronger than monolithic lithium disilicate restorations, while the chipping risk is minimized. In fact, even the weakest zirconia offers a significantly higher flexural strength than lithium disilicate (IPS e.max CAD LT, Ivoclar Vivadent)^2,3. Thanks to the high edge stability of zirconia after milling, the restorations are also highly stable, a favourable property for long-term success.

CONCLUSION

The flexural strength of zirconia is generally higher than that of lithium disilicate (800 to 1,200 MPa for zirconia versus 360 to 460 MPa for lithium disilicate), and due to the improved aesthetic potential of the available materials, a full porcelain layer is no longer required. Hence, zirconia restorations are usually very strong and durable.

3. FINISHING OF ZIRCONIA RESTORATIONS IS MORE COMPLICATED THAN FINISHING OF LITHIUM DISILICATE RESTORATIONS

When using modern, aesthetic zirconia materials, finishing techniques are quite similar. The most popular technique for both, high-translucency zirconia and lithium disilicate, is micro-layering. Based on a full-contour restoration design and a subsequent cutback limited to the vestibular area, a micro-layer of porcelain (often a specific porcelain line-up developed for micro-layering) is applied. With CERABIEN™ MiLai from Kuraray Noritake Dental Inc., the standard procedure consists of internal staining, the application of luster porcelains and final glazing. Fewer layers and fewer bakes are required compared to full porcelain layering. However, aesthetic zirconia can also be used for the production of monolithic restorations, which are characterized with paste stains and glazed.

CONCLUSION 

As a monolithic design or minimal cutback of restorations based on modern zirconia materials is an option, finishing of zirconia is just as easy as finishing of lithium disilicate restorations. The technique depends on the desired outcome.

4. ZIRCONIA-BASED RESTORATIONS ARE MORE INVASIVE THAN THOSE MADE OF LITHIUM DISILICATE

This myth is also based on the assumption that zirconia needs a thick porcelain layer on top to produce aesthetic results. Since this is not the case and great outcomes are possible with monolithic designs or micro-layering approaches, a minimally invasive preparation design is supported by the use of zirconia as a restorative material. Due to a comparatively high strength even of the high-translucency variants, the minimum wall thickness is quite low (e.g. 0.4 mm for veneers made of KATANA™ Zirconia UTML or STML and 0.5 mm for posterior crowns made of KATANA™ Zirconia HTML Plus)*. This allows for a defect-oriented tooth structure removal.

*In general, the minimum wall thickness depends on the product and the indication.

CONCLUSION 

Depending on the type of zirconia and the finishing method, zirconia supports the production of minimally invasive restorations.

5. DUE TO THEIR HARDNESS, MONOLITHIC ZIRCONIA RESTORATIONS HARM THE OPPOSING DENTITION

When manufacturers of dental zirconia started promoting the monolithic use of zirconia, in-vitro studies were soon available to prove that it is not the hardness of the material, but the smoothness of the surface that determines how kind or harmful a dental restoration is to the opposing dentition^5-8. According to those studies, well-polished zirconia surfaces maintained their smoothness and showed a superior self-wear and wear to the opposing tooth structure compared to other restorative materials including lithium dislilicate^6-8. As glaze - unlike the polished surface - tended to wear off over time, it was stressed that a perfectly polished restoration surface is essential for a wear-friendly long-term behaviour. The in-vitro study results were also confirmed in vivo^9,10. According to the latest umbrella review focusing on this topic, polished monolithic zirconia causes lower antagonist enamel wear than metal ceramics, feldspathic porcelains and lithium disilicate tested¹⁰.

CONCLUSION 

Provided that the surface is smooth, monolithic zirconia restorations are kind to the opposing natural tooth structure. Over time, the opposing enamel wear may be expected to be on a similar level as natural enamel wear.

6. ADHESIVE LUTING OF ZIRCONIA-BASED RESTORATIONS IS IMPOSSIBLE

When oxide ceramics like zirconia are processed and pre-treated in the same way as silicate ceramics like lithium disilicate, the obtained bond strength is lower. Using the correct pre-treatment protocol, however, it is possible to establish a strong and durable chemical bond between the tooth structure and the zirconia. Otherwise, it would not be possible to place single-retainer resin-bonded bridges made of high-strength zirconia (3Y-TZP) successfully, for example. Their design is largely non-retentive, so that a strong bond is of paramount importance. It is established by air-abrading the bonding surface of the zirconia retainer wing with aluminium oxide (50 μm) at a low pressure (approx. 1 to 2.5 bar) after try-in^11,12, followed by ultrasonic cleaning, the use of a restoration primer that contains 10-MDP¹³ and the application of a high-performance resin cement like PANAVIA™ V5 (Kuraray Noritake Dental Inc.)¹⁴. Using this protocol with a predecessor of the resin cement just mentioned, ten-year survival and success rates were above 90 percent¹⁵. The described protocol is in line with the APC concept recommended by Prof Dr. Markus Blatz, which includes (A) airborne-particle abrasion, (P) zirconia primer, and (C) adhesive composite resin application¹⁶.

CONCLUSION

Using an appropriate protocol including small particle air-abrasion after try-in and a high-performance adhesive resin cement system with MDP primers, a strong and long-lasting chemical bond to zirconia can be established.

7. ZIRCONIA IS UNSUITABLE FOR RUSH CASES DUE TO THE NEED OF SINTERING THE RESTORATIONS AFTER MILLING

By using zirconia variants that are suitable for speed sintering, smaller restorations can be produced within very short time. Single-unit restorations and small bridges (up to three units) made of materials of the KATANA™ Zirconia Multi-Layered Series, for example, may be speed-sintered within 54 minutes, provided that a suitable furnace is used. This leads to a considerable reduction of the production time and is a great option for rush cases. For a true chairside workflow and same-day dentistry, KATANA™ Zirconia Block is a great option. It offers the same optical and mechanical properties as KATANA™ Zirconia STML and can be sintered even faster – in just 18 minutes.

CONCLUSION

By using suitable zirconia materials and equipment, production times of zirconia restorations are no longer an issue when it comes to rush cases.

8. ALL HIGH-STRENGTH CERAMICS HAVE A SIMILARLY WIDE RANGE OF INDICATIONS

In fact, the range of indications varies with the flexural strength and fracture toughness of the materials. While the use of lithium disilicate is limited to the production of single-tooth restorations and small bridges, zirconia typically covers a wider range of indications, with the high-strength variants being even suited for long-span bridges. The most versatile variants of zirconia are those with flexural strength gradient – like KATANA™ Zirconia YML. This material offers a particularly high translucency in the enamel layer and a high strength in the body layers. Therefore, it is well suited for the production of single-tooth restorations and of highly complex structures such as long-span bridges – depending on where the restoration is positioned in the disc.

CONCLUSION

Zirconia offers a wider range of indications than lithium disilicate. By selecting one of those variants with a multi-layered structure offering flexural strength gradation, it is possible to cover virtually every indication, while other variants are better suited for specific needs (highest translucency option for aesthetically demanding cases, highest strength option for complex long-span designs).

ZIRCONIA A TRUE ALLROUNDER

Modern versions of dental zirconia are high-performance materials with well-balanced optical and mechanical properties typically suitable for a wide range of indications. As a zirconia user, you may choose to employ a single material with flexural strength gradation for virtually every situation or prefer to select different products depending on case-specific demands. You have the freedom to select the preferred finishing technique from traditional layering to just polishing and may opt for minimally invasive restoration designs. The latter is due to proven protocols establishing a long-lasting bond to zirconia. For everyone with particularly high quality demands, the KATANA™ Zirconia Multi-Layered series is worth a try. The raw material composition is unique, the powder is developed in-house in Japan and the blanks are produced in a perfectly aligned procedure delivering a homogeneous, densely pressed material for restorations with an accurate fit, high strength and superior edge stability.

REFERENCES

<sup>1. F. Beuer, J. Schweiger, ConsEuro 2015 London, Kuraray Satellite Symposium, May 14th 2015. 
2. Kwon SJ, Lawson NC, McLaren EE, Nejat AH, Burgess JO. Comparison of the mechanical properties of translucent zirconia and lithium disilicate. J Prosthet Dent. 2018 Jul;120(1):132-137. 
3. Reale Reyes A, Dennison JB, Powers JM, Sierraalta M, Yaman P. Translucency and flexural strength of translucent zirconia ceramics. J Prosthet Dent. 2023 Apr;129(4):644-649. 
4. Harada K, Raigrodski AJ, Chung KH, Flinn BD, Dogan S, Mancl LA. A comparative evaluation of the translucency of zirconias and lithium disilicate for monolithic restorations. J Prosthet Dent. 2016 Aug;116(2):257-63. 
5. Janyavula S, Lawson N, Cakir D, Beck P, Ramp LC, Burgess JO. The wear of polished and glazed zirconia against enamel. J Prosthet Dent. 2013 Jan;109(1):22-9. 
6. Preis V, Weiser F, Handel G, Rosentritt M. Wear performance of monolithic dental ceramics with different surface treatments. Quintessence Int. 2013 May;44(5):393-405. 
7. Lawson NC, Janyavula S, Syklawer S, McLaren EA, Burgess JO. Wear of enamel opposing zirconia and lithium disilicate after adjustment, polishing and glazing. J Dent. 2014 Dec;42(12):1586-91. doi: 10.1016/j.jdent.2014.09.008. Epub 2014 Sep 23. PMID: 25257823. 
8. Sripetchdanond J, Leevailoj C. Wear of human enamel opposing monolithic zirconia, glass ceramic, and composite resin: an in vitro study. J Prosthet Dent. 2014 Nov;112(5):1141-50. 
9. Hartkamp O, Lohbauer U, Reich S. Antagonist wear by polished zirconia crowns. Int J Comput Dent. 2017;20(3):263-274. 
10. Shah N, Nerkar H, Badwaik P, Ahuja B, Malu R, Bhanushali N. An evaluation of antagonist enamel wear opposing full-coverage zirconia crowns versus other ceramics full-coverage crowns and natural enamel - An umbrella review. J Indian Prosthodont Soc. 2024 Jul 1;24(3):217-224. 
11. Kern M. Bonding to oxide ceramics—laboratory testing versus clinical outcome. Dent Mater. 2015 Jan;31(1):8-14. 
12. Kern M, Beuer F, Frankenberger R, Kohal RJ, Kunzelmann KH, Mehl A, Pospiech P, Reis B. All-ceramics at a glance. An introduction to the indications, material selection, preparation and insertion techniques for all-ceramic restorations. Arbeitsgemeinschaft für Keramik in der Zahnheilkunde. 3rd English edition, January 2017. 
13. Al-Bermani ASA, Quigley NP, Ha WN. Do zirconia single-retainer resin-bonded fixed dental prostheses present a viable treatment option for the replacement of missing anterior teeth? A systematic review and meta-analysis. J Prosthet Dent. 2021 Dec 7:S0022-3913(21)00588-6. 
14. Bilir H, Yuzbasioglu E, Sayar G, Kilinc DD, Bag HGG, Özcan M. CAD/CAM single-retainer monolithic zirconia ceramic resin-bonded fixed partial dentures bonded with two different resin cements: Up to 40 months clinical results of a randomized-controlled pilot study. J Esthet Restor Dent. 2022 Oct;34(7):1122-1131. 
15. Kern M, Passia N, Sasse M, Yazigi C. Ten-year outcome of zirconia ceramic cantilever resin-bonded fixed dental prostheses and the influence of the reasons for missing incisors. J Dent. 2017 Oct;65:51-55. doi: 10.1016/j.jdent.2017.07.003.
16. Blatz MB, Alvarez M, Sawyer K, Brindis M. How to Bond Zirconia: The APC Concept. Compend Contin Educ Dent. 2016 Oct;37(9):611-617; quiz 618.</sup>

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Clinical case by Kostia Vyshamirski, DT

Digital technologies for computer-aided imaging, planning, design and manufacturing are valuable tools that support dental technicians in their daily work. Combined with traditional approaches, those digital tools allow us to assess, shape, and finally meet or even exceed patient expectations. The case below is a perfect example: We produced 20 natural bleach restorations made of KATANA™ Zirconia YML and CERABIEN™ ZR Porcelains and of Noritake Super Porcelain EX-3 (Kuraray Noritake Dental Inc.), respectively.

INITIAL SITUATION

The aim was to create a new white, still natural smile. It was decided to replace the old crowns in the maxilla and to create a wider and brighter smile by adding laminate veneers in the maxilla and mandible.

Fig. 1. Initial clinical situation.

DIGITAL SMILE DESIGN AND DIAGNOSTIC WAX-UP

Digital smile design and a diagnostic wax-up are great tools for analysing and planning a new smile. Intraoral scans and portrait photographs of the patient served as the basis for the development of the ideal proportions and shapes. Once the virtual designing of the new restorations was completed (software: exocad DentalCAD), the wax-up models were printed. By transferring the wax-up into the patient’s mouth via an index or matrix, it is possible to test and assess the outcome intraorally. In this step, aesthetic and functional analysis should be the priority.

Fig. 2. Digital smile design based on an image.

Fig. 3. Computer-aided waxing up in the maxilla based on the smile design.

Fig. 4. Completed virtual wax-up for the maxilla and mandible.

Fig. 5. Wax-up transferred into the patient’s mouth for functional and aesthetic analysis.

Fig. 6. The planned new bright smile.

ALVEOLAR PRINTED MODEL

Precise and functional models are essential for the production of accurate, aesthetic restorations in the laboratory. The model builder software SHERAeasy-model (SHERA) and a 3D printer (ASIGA MAX UV, Asiga) were used to produce solid models and alveolar models with full gingival information and removable dies.

Fig. 7. Alveolar models printed in gingiva and tooth colours.

Fig. 8. Printed models with articulator holding plates and removed dental elements.

REFRACTORY DIE DUPLICATION AND ARTICULATION

The refractory die technique allows for the production of extremely thin-walled restorations and hence supports minimal tooth structure removal. For this reason, the approach seems best suited for all previously untreated teeth without major defects. The printed dies were duplicated in the refractory die material before mounting the models in the articulator for a transfer of the maxillomandibular relations.

Fig. 9. Process of duplicating printed dies in the refractory material.

Fig. 10. Articulating the models.

PRODUCTION OF THE RESTORATIONS

To achieve the best results, it is essential to select the best material for each specific situation. For the production of the crown frameworks used to restore the six maxillary anterior teeth, KATANA™ Zirconia YML in the shade NW appeared to be the ideal option. Their intaglio surfaces were treated with Esthetic Colorant (Kuraray Noritake Dental Inc.) in the shade OPAQUE to prevent a shining through of the discolourations found on some of the prepared teeth. After sintering of the frameworks in a high-temperature sintering furnace (Nabertherm) at 1,550° C, CERABIEN™ ZR porcelains were applied as illustrated below. For the creation of natural effects inside the restorations – i.e. between the layers of porcelain –, we use the internal stain technique (ILS). This procedure is very predictable and fast. Each step during porcelain build-up and staining was recorded with photos to monitor the entire process and to capture all information on the individual protocol steps. The porcelain veneers (Super Porcelain EX-3, Kuraray Noritake Dental Inc.) were produced on the refractory dies to restore the premolars in the maxilla and central incisors to second premolars in the mandible.

Fig. 11. Refractory dies and zirconia frameworks on the model.

Fig. 12. Wax-up on the model with removable dies.

Fig. 13. KATANA™ Zirconia YML frameworks on the model.

Fig. 14. Opacity control with CERABIEN™ ZR Opacious Body OB White to optimise brightness.

Fig. 15. Application of CERABIEN™ ZR Body NW0.5 to restore the cores of the crowns using a silicon index.

Fig. 16. CERABIEN™ ZR porcelains E1 and LTX applied to create translucency at the incisal edge.

Fig. 17. Prepared surface ready for internal stain application.

Fig. 18. Creation of mamelons and incisal effects with CERABIEN™ ZR internal stains.

Fig. 19. Adaptation of the incisal third with a mamelon mixture of internal stain shades (white, mamelon orange and bright).

Fig. 20. Outcome of the internal staining procedure.

Fig. 21. CERABIEN™ ZR Luster application using the Interchangeable Build-up Technique, application of CCV1 in the cervical area.

Fig. 22. CERABIEN™ ZR porcelains ELT1 used for the core, LTX for the incisal area and ELT3 for the ridges.

Fig. 23. Restorations finished by carving, hand polishing and a self-glaze bake.

Fig. 24. Layering map summarizing the porcelain layering procedure.

FIT ASSESSMENT AND TRY-IN

When the production process was complete, the restorations were placed on the solid models (printed master casts). This step is very important to validate the passive fit and contact points of each crown and veneer. Afterwards, it was time to try-in and check all the restorations intra-orally.

Fig. 25. Final restorations ready for fit assessment.

Fig. 26. Maxillary restorations: Checking of the passive fit and contacts on the model.

Fig. 27. Mandibular restorations: Checking of the passive fit and contacts on the model.

Fig. 28. Intra-oral try-in of the crowns.

DEFINITIVE PLACEMENT AND FINAL OUTCOME

Refractory ceramic veneers were cemented via an adhesive protocol using a resin-based composite. Opaque glass ionomer cement was used to cement the zirconia crowns.

At the recall about one month after restoration placement, we saw amazing gum conditions and a happy, healthy and beautiful smile!

Fig. 29. Image taken right after definitive placement of the crowns.

Fig. 30. Nice pink-and-white aesthetics achieved with the all-ceramic restorations.

Fig. 31. Amazing gum conditions found one month after restoration placement.

Fig. 32. Happy, healthy and beautiful smile.

Fig. 33. The new smile exceeds expectations.

Dentists:

Interview with Mathias Fernandez Y Lombardi

INTRODUCING CERABIEN™ MiLai LOW-FUSING PORCELAINS AND INTERNAL STAINS

Highly aesthetic lithium disilicate or zirconia-based framework materials combined with a micro-layer of porcelain are becoming the new standard for producing lifelike all-ceramic restorations. For those wondering why it’s worth adopting the new technique, how to start, how to improve and which materials to use, we had a conversation with a true expert in all things ceramic: Mathias Fernandez Y Lombardi, Head of Technical Marketing – Europe at Kuraray Europe GmbH.

Mathias Fernandez Y Lombardi, do you believe in micro-layering as a technique that is capable of streamlining procedures in the dental laboratory while fulfilling high aesthetic demands?

Yes, I truly believe that micro-layering is the next step in the evolution of indirect restorative techniques and materials. This evolution is driven by improvements in the area of framework materials, which are becoming more and more tooth-like in their appearance. We have moved from metal to opaque, high-strength zirconia and – more recently - high-translucency multi-layered zirconia and lithium disilicate, which no longer require thick porcelain layers to achieve lifelike outcomes. In this context, it’s only natural that a new technique has emerged.

Kuraray Noritake Dental Inc. is well-known as a pioneer in multi-layered zirconia technology and veneering porcelains. Are there any products particularly suitable or specifically developed for micro-layering?

We offer a series of high-translucency, multi-layered zirconia perfectly suited for micro-layering on the one hand and an aligned portfolio of internal stains and porcelains specifically developed for micro-layering on the other. The zirconia portfolio includes three different blank types with a multi-layered colour structure (KATANA™ Zirconia UTML, STML and HTML Plus), one variant with flexural strength, translucency and colour gradation (KATANA™ Zirconia YML), but also the timeless classic HT for the frameworks should be mentioned. While the first three offer a uniform strength and are chosen based on the indication, KATANA™ Zirconia YML with its multi-layered strength is a universal material suitable for an extremely wide range of applications.

The set of internal stains and porcelains specifically designed for the micro-layering technique that we just introduced is CERABIEN™ MiLai. With this addition to the CERABIEN™ family, we offer a perfect complement to the KATANA™ Zirconia Multi-Layered series, and with it, a revolutionary workflow that significantly deviates from traditional methods, enabling us to deliver greater efficiency, cost savings, and more flexibility. However, CERABIEN™ MiLai is not only compatible with KATANA™ Zirconia, but also with aesthetic zirconia from other manufacturers and reinforced silicate ceramics such as lithium disilicate with a CTE value within 9.5-11.0×10-⁶/K (50 °C – 500 °C).

Fig. 1. Overview of CERABIEN™ MiLai Low-Fusing Porcelains.

Fig. 2. Overview of CERABIEN™ MiLai Internal Stains.

Why should a dental technician start using the micro-layering technique and invest in a new set of porcelains for this purpose?

The reasons to start micro-layering are obvious: depending on the design, micro-layering can eliminate or minimize the chipping risk. Moreover, the technique is highly efficient, as the number of layers and bakes is drastically reduced. This results in a reduced thickness of the restoration facilitating minimally invasive preparations and a less complex layering procedure that even beginners are able to learn and implement very quickly. A new set of porcelains specifically developed for micro-layering like CERABIEN™ MiLai can further support the feasibility of the technique and the quality of the outcomes achieved even by beginners. Due to the shortage of skilled workers in dental laboratories, this aspect is becoming increasingly important.

How does CERABIEN™ MiLai support users in achieving aesthetic, high-quality outcomes right from the start?

With traditional porcelain systems, it can be challenging to create all the desired individual shade effects in a layer of only 0.03 mm to 0.6 mm thickness. With CERABIEN™ MiLai, this isn’t the case as the system is specifically designed for this purpose. The saturation and translucency of the porcelains are matched to the framework materials and adjusted to the volume of the porcelain layer. The compact line-up makes it quite easy to select and combine the right shades for satisfying results right from the start. More experienced users can mix the different components for additional effects, so that there are no limits to their creativity.

Images courtesy of MDT Daniele Rondoni.

Fig. 3. Virtually unlimited design options: crown with a full micro cut-back, crown with a vestibular cut-back and monolithic restoration.

Furthermore, the versatility of CERABIEN™ MiLai is a key feature that results in great outcomes. The system can be used on lithium disilicate and zirconia, a monolithic surface, a vestibular cut-back or a full micro cut-back. With this broad application spectrum, dental technicians are likely to use CERABIEN™ MiLai daily, which allows them to develop a true understanding of the components and to establish work routines very quickly. As a consequence, the outcomes become predictable and controllable. This is further supported by consistent handling and optical properties – all the result of a single core technology.

Please tell us more about this technology.

The core technology used in CERABIEN™ MiLai is synthetic feldspathic ceramic technology. Originally developed for Super Porcelain EX-3 and adjusted to the specific needs of CERABIEN™ ZR in the first step and CERABIEN™ MiLai more recently, this technology is responsible for consistent properties. This is because the formulation never needs to be aligned due to changing natural components. However, I believe that the greatest benefit of using feldspathic porcelain lies in the elimination of shadow effects. Everyone familiar with layering natural feldspathic porcelains on ceramics will know the typical greyish shadows appearing in restorations after several firing cycles. They originate from inhomogeneities in the material caused by micro-movements during firing. Showing no movements in this phase, synthetic felspathic porcelains from Kuraray Noritake Dental Inc. are the first and only porcelains preventing this effect. Finally, the further developed version of the technology allowed us to realize a low firing temperature of just 740 °C while maintaining the desired coefficient of thermal expansion. This is essential for the material’s compatibility with lithium disilicate.

Are there any other benefits arising from the low firing temperature?

The low firing temperature definitely offers an economic benefit, as the process consumes less energy and takes less time compared to high-temperature firing cycles. Moreover, the wear of the furnace is reduced. Finally, the low temperature is of interest for users of CERABIEN™ ZR in specific indications: Some ceramists like to combine the systems especially in cases with artificial gingiva. They create the porcelain work on the teeth with CERABIEN™ ZR first and then individualize the gingival area with CERABIEN™ MiLai. Due to the low firing temperature, the form, colour and surface of the previously applied veneering porcelain will remain stable.

Image courtesy of MDT Ioulianos Moustakis.

Fig. 4. Application of CERABIEN™ MiLai Tissue Porcelains on a complex restoration with the teeth already finalized.

Image courtesy of MDT Ioulianos Moustakis.

Fig. 5. Application of CERABIEN™ MiLai Internal Stains on a zirconia bridge.

Do you have any application technique recommendations for CERABIEN™ MiLai?

The best aesthetic outcomes are obtained by using the internal stain technique. By applying the stains first, it is possible to create natural depth effects despite the minimal thickness of the porcelain layer. The stains are easy to use and the outcomes are impressive. The micro-layer of porcelain applied on top acts like a window imitating the enamel, which contributes to a tooth-like appearance. Due to the compact line-up and easily manageable effects, this technique is even suitable for beginners.

Is the procedure different depending on the base material (lithium disilicate versus zirconia)?

Most of the steps are identical. However, surface conditioning may be different depending on the material used (as described in the material manufacturer’s instructions for use). Moreover, Value Liner 1 or Value Liner 2 is typically used on lithium disilicate for wash baking, whereas Translucent or Luster are recommended for this step on zirconia. When space is limited, internal stains may be applied directly. All following steps – the optional but highly recommended application of internal stains, the building-up of Translucent or Luster and baking, morphological corrections, the glaze bake and finishing – are identical.

What are the options for glazing?

CERABIEN™ MiLai porcelains offer a self-glaze effect obtained by fine-polishing (with PEARL Surface C) followed by glaze baking. This leads to a natural gloss, while maintaining the anatomical details. Alternatively, CERABIEN™ ZR FC Paste Stain Glaze or Clear Glaze can be applied and fixed by baking. These liquid ceramics allow users to add some structural details, while the surface appears glossier. However, the procedure is more time-consuming due to the additional application step.

Do you have any recommendations regarding the indication-specific selection of the framework or base material?

Traditionally, lithium disilicate has been the material of choice for aesthetic single anterior restorations, while zirconia was predominantly used for multi-unit restorations and restorations in the posterior area. With the availability of KATANA™ Zirconia STML / UTML and CERABIEN™ MiLai, zirconia is becoming increasingly attractive for the production of minimally invasive veneers, crowns and the like. A thin-walled restoration made of KATANA™ Zirconia, speed-sintered in just a few minutes and combined with a thin layer of CERABIEN™ MiLai, results in an incredibly strong restoration with several aspects that lithium disilicate simply cannot match. The preparation technique for zirconia is much more favourable for dentists - for example marginal adaptation and biocompatibility, especially regarding gingival healing, are superior. Aesthetically, there is no risk of a greyish effect when using zirconia with CERABIEN™ MiLai, while lithium disilicate needs to be treated with Value Liner to prevent this. Additionally, the ease of cementation with PANAVIA™ SA Cement Universal further enhances the quality of the restoration in the fastest possible timeframe, allowing for quick and flexible responses to dentists’ needs.

You mentioned speed sintering as a factor contributing to a streamlined workflow. Studies have shown, however, that this step might weaken the mechanical and aesthetic properties of zirconia. Do you recommend speed sintering despite this fact?

Indeed, speed sintering does affect the translucency and flexural strength of some zirconia variants. This is probably the reason why dental technicians have been reluctant to change their established practices of sintering overnight – despite the availability of high-speed furnaces. However, KATANA™ Zirconia is an exception: Due to our unique powder formulation, we are able to offer zirconia with a composition that is completely independent from other brands of dental zirconia. With this, we are able to fundamentally change the traditional workflow of an end-user and offer more flexibility, speed and efficiency, resulting in less energy consumption, stress and costs. In a study conducted at the Division of Biomaterials at the University of Alabama at Birmingham¹, three different high-translucency zirconia materials including KATANA™ Zirconia Block (KATANA™ Zirconia STML) were sintered according to a traditional and a high-speed sintering schedule. Prior to sintering and afterwards, the three-point bending strength, translucency and grain structure were analysed. The material from Kuraray Noritake Dental Inc. was the only zirconia with properties that remained unaffected after speed sintering. Internal testing confirmed this finding for all variants of the KATANA™ Zirconia Multi-Layered series. As a result, we do recommend speed sintering of our materials, delivering true economic and time advantages.

With highly potent materials for micro-layering now available, do you think that full ceramic layering is going to be a thing of the past?

I am convinced that in the near future the great majority of dental restorations will be produced using aesthetic framework materials and simplified micro-layering techniques. However, full porcelain layering is here to last. There will always be a demand for a few highly-skilled ceramists serving the needs of individuals with the highest aesthetic demands. It is like tailor-made versus off-the-peg suits: the tailor-made ones are the best you can buy, but most people wear off-the-peg ones, which are perfectly adequate in virtually every environment.

Thank you very much!

Reference

1. Lawson NC, Maharishi A. Strength and translucency of zirconia after high-speed sintering. J Esthet Restor Dent. 2020 Mar;32(2):219-225. doi: 10.1111/jerd.12524. Epub 2019 Sep 13. PMID: 31515932.

Mathias Fernandez Y Lombardi

EU Scientific Manager
Dental Ceramics & CAD/CAM Materials
Kuraray Europe GmbH

2013
Successful completion of an apprenticeship as a dental technician at Seuthe dental laboratory in Plettenberg, Germany

2018
Successful completion of dental technology studies at the University of Osnabrück, Germany. Graduation as an engineer in dental technology

Since March 2018
Employee of Kuraray Europe GmbH

This year, the Kuraray Noritake Dental stand will be packed with news from the world of dentistry, so we offer not just one reason to visit, but a whole range: new chairside products, new labside products, inspiring lectures, enlightening hands-on demonstrations… And the best thing? You don´t have to choose just one thing, come and see them all at the Kuraray Noritake Dental booth in Hall 11.3 | Stand E010!

Chairside – smart streamlined solutions

When it comes to a dental practice, our vision is clear: a world where your materials and tools work seamlessly in your hands, where complexity is minimized, and where you are given enough time to focus on what matters most: the individual desires and needs of every single patient. This is the future of dentistry - and we are leading the way. Come discover our new additions to the UNIVERSAL EXCELLENCE family: a flowable universal composite and a new generation of a universal bond!

Labside – speed and aesthetics hand in hand

No matter whether a minimally invasive procedure or the best aesthetic outcomes are desired: Kuraray Noritake Dental has the products for you. New in the portfolio: CERABIEN™ MiLai - low-fusing porcelains and internal stains. Come and see for yourself its ultra-thin layering, exceptional mechanical properties and consistent handling for both zirconia and lithium disilicate. And while you're there, have a coffee while speed-sintering with our KATANA™ Zirconia discs takes place in real time.

Get inspired by 12 expert speakers on 2 stages

Are you a user of or interested in one of Kuraray Noritake Dental’s products or solutions, but eager to learn more about their practical use from proven experts in your field? From Wednesday until Saturday, we offer a programme of exciting lectures and live demonstrations - this time simultaneously on two stages: one dedicated to chairside and the other one to labside topics!

Warm welcome

Everyone, from sales person to scientific marketeer, looks forward to giving you a warm welcome, answering your questions and introducing you to the world of innovative Kuraray Noritake Dental products, solutions and workflows. And while you are already in Cologne anyway, why not enjoy the breathtaking beauty of the old town? Have you ever seen its famous Gothic Cathedral? Or its Old Town inviting you to stroll through its narrow alleys, finding traces of history around every corner? This year's IDS offers so many reasons to attend that it's hard not to accept the invitation.

Additional information and the full programme of lectures and hands-on courses at the IDS is available online.

DELICATE BALANCE BETWEEN COSTS AND AESTHETICS IN DENTAL LAB

When you are a lab owner striving to achieve high-end results using modern digital techniques, the initial investment in CAD/CAM technology is significant, followed by ongoing costs for expendable items such as milling tools and blanks. That cost can be reduced by selecting universal, high-quality materials.

Undoubtedly, zirconia stands out as one of the most popular materials on the market. From an inventory perspective, however, lab owners often find themselves purchasing multiple discs of the same shade and thickness. The reason is that they need to meet all requirements for strength and aesthetics in different settings – enabling them to cover all kinds of restorations and deliver excellent patient outcomes.

UNIVERSAL SOLUTION FOR DENTAL LABS

At Kuraray Noritake Dental Inc., we take pride in not only developing the first-ever multilayer zirconia, KATANA™ Zirconia ML, but also in our commitment to delivering the highest quality materials that we can.

KATANA™ Zirconia YML, our latest addition to the KATANA™ Zirconia line-up, exemplifies this dedication and offers universal applicability. The universal feature is based on the fact that KATANA™ Zirconia YML disc not only offers colour gradation, but also impressive flexural strength and translucency gradation, with maximum values of up to 1,100 MPa and 49 % translucency, respectively.

INHOUSE PRODUCTION - THE PATH TO HIGH QUALITY ZIRCONIA DISC

Like all our zirconia offerings, KATANA™ Zirconia YML begins its journey to the dental lab in our Japanese facility where raw zirconia powder undergoes special treatment process before the addition of essential components.

Once the material has undergone this thorough initial stage, it progresses to the pressing and pre-sintering phase to form the disc. Every detail is carefully calculated, managed and controlled. This phase of the process takes several days, underscoring our goal to achieve the most aesthetic product.

HIGH-SPEED SINTERING PROGRAM: 54 MINUTES

The unique powder formulation and refinement process, as well as the pressing and pre-sintering technique, is the key to allow our customers to realize restorations of up to three-unit bridges without any compromise in terms of aesthetics or mechanical properties using the 54-minute high-speed sintering* process.

This high quality, lengthy production process results in an exceptionally dense material, which once sintered, goes on to deliver a high strength, high aesthetic final restoration.

HIGH PRECISION SHRINKAGE AND STABLE CTE VALUES FOR EXCEPTIONAL FIT

Outstanding deformation stability during the sintering procedure, contributes to the stability during the final sintering process in the dental laboratory, providing for an exceptional fit of large-span bridges and other restorations.

MULTI-LAYERED STRUCTURE AND EASE OF POSITIONING OF RESTORATIONS IN THE BLANK

To enhance aesthetic qualities, all KATANA™ Zirconia YML discs are designed using ratios rather than fixed measurements of different layers in the multi-layered structure. This means that regardless of the disc's thickness, there is always a consistent ratio of 35 % of raw material that constitutes the translucent enamel zone. Hence, discs with an increased height, which are typically used for the production of larger restorations, will always offer sufficient space in the enamel zone, while smaller discs are optimized for smaller restorations.

ONE DISC. ALL INDICATIONS.

These qualities empower dental lab owners to deliver a wide range of restorations. The material is suitable for single crowns to full-arch structures, for full-contour designs to conventional frameworks, using a single material without compromising on aesthetics: KATANA™ Zirconia YML. For finishing, we offer a well-aligned portfolio of solutions designed for internal and external staining, micro-layering and full layering.

EXPLORE KATANA™ Zirconia YML: WEALTH OF RESOURCES, CLINICAL CASES AND FAQS

Visit our website to discover more about KATANA™ Zirconia YML. You will find useful materials such as brochure, technical guide, in-depth technical information.

Would you like to see the material in action – browse the blog section of our website that offers a variety of clinical cases and articles by world-renowned experts showcasing and proving the versatility and aesthetics of KATANA™ Zirconia YML.

*The material is removed from the furnace at 800°C. A furnace with a configurable KATANA™ Zirconia YML firing program is required.

Case by Martin Laurik, MDT

There are so many different restorative materials out there and so many design and finishing concepts available that it often seems difficult to select the best option for a specific case. Using an allrounder like KATANA™ Zirconia YML can facilitate decision making: It is a great choice for single- to multi-unit restorations, works on teeth and implants alike, and can be adapted to individual needs by selecting a suitable design concept and adequate finishing technique. In this way, it is even possible to solve aesthetically challenging cases as the one illustrated below.

Initial situation and temporization

This patient was in need for treatment after the loss of her maxillary right central incisor and the placement of an implant in this region. As a replacement of the restorations on the other three maxillary incisors was necessary as well, it was decided to produce four crowns made of the same material – KATANA™ Zirconia YML. For aesthetic evaluation of the restorations’ length, angulations and shape in the mouth and a functional test drive, the crowns were digitally designed in full contour and milled from PMMA in the determined tooth shade A2 (Fig. 1).

Fig. 1. Full-contour PMMA crowns on the master cast.

Design, milling and effect dyeing of the zirconia crowns

Once the appearance and functional aspects of the temporary restorations were approved by the patient and the restorative team, the definitive crowns were produced. Their design was based on the full-contour design of the temporaries; however, a facial reduction of 0.6 mm was carried out by the software to create space for individualization with a small layer of veneering porcelain. The crowns were then milled from a KATANA™ Zirconia YML disc in the shade A1 – approximately one shade lighter than the determined tooth shade. To mask the uneven colour from the tooth stumps and the implant abutment, the intaglio of the crowns was treated with Esthetic Colorant in the shade Opaque. Some individual and intensified colour effects on the vestibular surface were also created with Esthetic Colorant.

Internal staining and porcelain layering

To slightly adjust the chroma and lightness, a first layer of CERABIEN™ ZR Internal Stains was added, followed by a wash bake. After the application of a first layer of CERABIEN™ ZR porcelains (Body, Enamel and Translucent) and baking (Fig. 2) – the central incisors received a layer of A1B, the lateral incisors a mixture of A1B and A2B (slightly darker to provide for a better match with the canines) with LT1, LT Natural completing the picture – additional internal staining was carried out (Fig. 3). The final layer of CERABIEN™ ZR luster porcelains (LT1, ELT2 used on the convex line angles to achieve an external reflection) was added and fixed in a fourth bake (Fig. 4).

After adjustments and very rough polishing, a self-glaze firing programme was selected (firing temperature 915 °C, holding time 5 seconds). On the highly polished incisal and palatal parts of the crowns and for contact point adjustment, CERABIEN™ ZR FC Paste Stain Glaze was applied and fixed with the same bake. The finished crowns on the model are shown in Figure 5, while Figure 6 displays the final treatment outcome.

Fig. 2. Crowns milled from KATANA™ Zirconia YML with a facial cutback of 0.6 mm after individualization with Esthetic Colorant, sintering, internal staining and the application of a first layer of porcelain.

Fig. 3. This picture shows the subtle internal stain adjustment to the ceramic mostly on the incisal part.

Fig. 4. Crowns prior to final shape adjustments and polishing.

Fig. 5. Finished crowns on the model.

FINAL SITUATION

Fig. 6. Treatment outcome.

Easy approach to beautiful restorations

The presented approach is a relatively easy way of producing highly aesthetic anterior restorations. Using an allrounder zirconia combined with a few selected effect liquids, internal stains and luster porcelains, it is possible to achieve a great optical integration even in a situation where teeth and implants need to be restored. The natural shape and surface texture of the restorations plays an important role in this context, as does the base material – a naturally shaded, highly translucent zirconia.

Dentist:

MARTIN LAURIK, MDT

Martin started working as a dental technician in 2014. In the time since, he never stopped training and learning from renowned colleagues. Continuing education courses focused on dental ceramics and occlusion in the functional concept of Slavicek. Fascinated by the beauty of natural teeth, developing an understanding of their complexity and learning how to mimic nature’s design as closely as possible has always been his primary goal, while he is well aware that there is still a lot to be learned and explored on the road to excellence.

KATANA™ Zirconia YML offers an unmatched blend of aesthetics and mechanical properties, but also provides for cost and time efficiencies.

Recognised for its strength and density at point of manufacture, the material delivers incredible hardness in its green state. This offers the fully validated opportunity to make adjustments in morphology directly after milling.

These qualities, along with its strength and translucency once sintered, deliver the possibility to produce a wide range of high aesthetic indications. KATANA™ Zirconia YML has set a new benchmark in prosthetic dentistry.

It provides dental technicians with a material that is truly universal with no compromises required.

KATANA Zirconia YML in a Nutshell

KATANA Zirconia YML represents a pinnacle of zirconia technology. With its multi-layered structure, it offers a seamless gradation of colour, strength and translucency that mimics natural teeth, making it an ideal choice for the entire indication spectrum.

The material's unique composition allows for high-speed sintering (up to 3-unit bridges), which significantly reduces production time without sacrificing optical or mechanical properties.

Colour Gradation and Physical Properties

The colour gradation of KATANA Zirconia YML is designed to replicate the natural colour transition of human teeth, from the dentin core to the translucent enamel surface.

This combined with the material's impressive flexural strength of up to 1,100 MPa and translucency of up to 49%, enables the production of restorations that are virtually indistinguishable from natural dentition.

Applications and Advantages of KATANA Zirconia YML

KATANA™ Zirconia YML's versatility extends to a wide range of indications, including crowns, veneers, inlays, onlays, and bridges of all sizes. With its strong body and highly translucent enamel layer, it offers exactly the properties required for an unlimited indication range.

Positioning of restorations in KATANA™ Zirconia YML discs is extraordinarily easy. The reason is that the gap between the lowest flexural strength found in the enamel area and the highest flexural strength found in the lowest body layer is comparatively small. Moreover, the Body Layer 1 that is found adjacent to the enamel layer already offers a flexural strength that is higher than the 800 MPa requested for bridges with four or more units. Consequently, the material is classified as a Class 5 zirconia and users are on the safe side whenever they place their long-span restorations in the middle of the blank.

Positioning of long-span restorations in the middle of the disc.

Revolutionizing Sintering with High-Speed Capabilities

One of the groundbreaking aspects of KATANA Zirconia YML is its compatibility with high-speed sintering protocols. This capability allows dental laboratories to expedite the production process, delivering high-quality restorations in a fraction of the time traditionally required. Sintered during normal working hours at daytime, small restorations can be finished within hours, while the sintering load at night is reduced automatically. Great option not only for rush cases!

The high-speed sintering process does not compromise the material's optical or mechanical properties, maintaining its aesthetics and strength.

Recommended Finishing Techniques for Optimal Results

KATANA Zirconia YML is a beautiful and aesthetic material in its own. Therefore, when it comes to finishing, CERABIEN™ ZR FC Paste Stain is a great option.

KATANA Zirconia YML: A Testament to Innovation in Dental Materials

KATANA Zirconia YML stands at the forefront of dental material technology, offering outstanding aesthetics, strength, and efficiency. Its introduction has marked a significant advancement in the capabilities of dental technicians, allowing for the creation of restorations that truly mimic the beauty of natural teeth in a fraction of time.

As the dental industry continues to evolve, KATANA Zirconia YML remains a testament to the relentless pursuit of excellence in restorative dentistry.

For more detailed information on KATANA Zirconia YML, including technical guide, FAQs and Clinical cases, visit Kuraray Noritake Dental's YML dedicated page.

Interested in articles, user experience or clinical cases using KATANA Zirconia YML? Check the blog section of our website! 

Mathias Fernandez Y Lombardi

EU Scientific Manager
Dental Ceramics & CAD/CAM Materials
Kuraray Europe GmbH

With PANAVIA™ SA Cement Universal and KATANA™ Zirconia

By using PANAVIA™ SA Cement Universal and its proprietary dual-monomer technology, you can now simplify the bonding of restoration to implant abutments without the use of separate primers or silane. Independent research has confirmed this new dual-monomer technology does not sacrifice adhesion or durability on glass-based ceramics or zirconia. The technique, in this case study, is for custom fabricated abutment & KATANA™ Zirconia YML crown, however, the basic technique on the treatment of the abutment and restoration may be used with any implant restoration combination as long as the proper surface treatments for type of material is followed.

INITIAL FIT OF ABUTMENT & RESTORATION

Basic technique on the treatment of the abutment and restoration.

Fig. 1. Check Initial Fit of Abutment & Restoration: abutment & crown margins should be checked to ensure proper fit.

Fig. 2. Protect base of implant with putty or light-cure block-out resin. The base of the implant should be covered so that it is not air abraded accidentally.

Fig. 3. Abrade titanium abutment with 50 μm alumina oxide powder.

Fig. 4. Clean abutment with KATANA™ Cleaner: Apply KATANA™ Cleaner by rubbing each area for 10 seconds.

KATANA™ Cleaner is a universal cleaner that is indicated to clean metal, zirconia & glass-based restorations. It is also an intra oral cleaner that may be used on dentin and enamel.

TREATMENT OF KATANA™ Zirconia RESTORATION WORKFLOW

Bonding to zirconia has been proven to be durable in research going back to the 1990’s with the original MDP adhesive monomer in the PANAVIA™ resin cements. The three requirements to bonding zirconia are:

1. Air abrade zirconia with 50 μm alumina oxide powder.
2. Clean zirconia
3. Apply an MDP-Based Primer or resin cement. PANAVIA™ SA Cement Universal contains the original MDP that was developed & patented in 1981 by Kuraray Dental.

Fig. 1. Air abrade KATANA™ Zirconia at 14-58 psi.

Fig. 2. Dispense & mix PANAVIA™ SA Cement Universal (it is available in automix or handmix formulations).

Fig. 3. Apply PANAVIA™ SA Cement Universal to the abutment or inside the crown.

Fig. 4. Seat restoration on abutment.

Fig. 5. Remove excess resin with a dry micro-applicator or brush.

Fig. 6. You may light-cure the margins after cleaning up all excess resin. If you fully cure excess resin, It can be difficult to remove. If difficult to remove, change curing time or distance with your light.

Fig. 7. Leave restoration on abutment to self-cure fully for approximately 10 minutes at room temperature.

Fig. 8. Final check of custom abutment KATANA™ Zirconia YML crown on model.

Dentist:

JEAN CHIHA

Technician Jean Chiha CDT, Santa Ana, CA USA

Mr. Chiha is the owner of North Star Dental Laboratory and Milling Center, Santa Ana, CA, and has served as President of the Dental Lab Owners Association of California since 2013. He is a 1985 graduate of Institut Dento Technic, a private dental technology school in France. Mr. Chiha lectures internationally on dental communication and case planning. Jean lectures around the world on a variety of topics and has carved out a niche with his extensive knowledge of zirconia. Affectionately referred to as “Mr. Katana” due to his involvement in the creation of the material.