Article by Dr. Bassem Jaidane

Among the most common problems in modern dentistry is that of restoring a patient‘s lost aesthetic dental appearance. To do this, new technologies are available to practitioners. For anterior teeth where aesthetics are paramount, dentists prefer the least invasive treatments possible, such as layered dental veneers (cut-back). In cosmetic dentistry, practitioners are often faced with cases requiring a multidisciplinary treatment plan or different types of restorative materials to be used at the same time. For cases of prosthetic restoration combining dental veneers, dental crowns and dental bridges, dentists are often faced with situations where the difference in shade is noticeable in the final result, this is explained by the difference in restorative material, product, adhesion technique, the thickness of the prosthetic element and the colour of the abutment, whether it is a living natural tooth, devitalized, or even an implant abutment^1-2.

In the presence of a treatment plan requiring dental veneers, crowns and dental bridges, choosing zirconia as the only restorative material is no longer an option but an obligation. The is due to the limited mechanical properties of lithium disilicate and feldspar porcelain restorations, which contraindicate their use as dental bridges. There are different factors explaining the reluctance of practitioners to use the zirconia dental veneer technique³: One is the absence of the vitreous phase. It makes impossible to create an optimal adhesion surface with hydrofluoric acid at the level of the intaglio of the zirconia veneers. Another is the lack of translucency of the first zirconia generations.

Modern zirconia materials, however, are particularly well-suited for cases requiring a combination of veneers, crowns and dental bridges of the same optical appearance. This is due to their increased translucency and excellent mechanical properties. The following article describes and discusses the realization of a clinical case treated with dental veneers and a crown using KATANA™ Zirconia UTML (Kuraray Noritake Dental Inc.). the veneers were placed with PANAVIA™ Veneer LC (Kuraray Noritake Dental Inc.). The patient presented an aesthetic problem at the level of an anterior implant-supported crown.

CASE OBSERVATION

Patient S, from the Tunisian Sahel, engineer in France, with no significant pathological history and aged 29, presented in January 2023 due to an aesthetic problem negatively affecting her smile. The extraoral examination was without abnormalities, while the intraoral examination showed good oral hygiene, healthy gums, a thin free gingiva and a protruded zirconia crown on an implant in the region of the maxillary right central incisor (figs 1 and 2).

Fig. 1. Initial clinical situation.

Fig. 2. Occlusal view revealing the volume and position of the crown on the central incisor.

During the preliminary interview, it turned out that the implant in the region of the right central incisor had been placed in 2020. The patient’s former dentist had left Tunisian territory. The patient does not have any document or reference on the dental implant, and she wishes to “straighten” the crown and improve the aesthetics of her smile before her planned wedding ten days after her first consultation.

TREATMENT PLAN

After having had the informed consent of the patient and after having asked the indication of dental veneers for aesthetic reasons, the treatment was initiated. According to the treatment plan, seven maxillary anterior teeth (from first premolar to first premolar) should receive an incisal overlap preparation (depth: 0.1 to 0.3 mm) for the placement of veneers made of KATANA™ Zirconia UTML. For the implant in the region of the right central incisor, it was planned to replace the existing crown by a crown made of KATANA™ Zirconia UTML without replacing the abutment. This was due to the lack of information about the implant type and the lack of time.

TREATMENT

After taking the preoperative photos (fig 3), choosing the color of the veneers and anesthetizing the maxillary anterior region, the incisal overlap preparation was carried out on the seven maxillary teeth and the zirconia crown was removed from the implant. A cylindrical diamond bur was used to separate the zirconia part from the abutment. Subsequently, a bite record and impressions were taken using the wash technique. In addition, a temporary crown was produced and placed on the abutment.

Fig. 3. Preoperative picture.

In the dental laboratory, virtual models were created based on the conventional impressions (fig. 4). Then, the zirconia restorations were designed in full contour, cut back for the veneering porcelain and finished by layering with CERABIEN™ ZR porcelain (Kuraray Noritake Dental Inc.). At try-in during the second session, we checked the insertion, the gingival margins, and the contact points between the veneers and the crown on the implant. Given the superior mechanical properties of the zirconia veneer, the shape and thickness of the veneers were modified chairside to have a harmonious anterior curve and a better aesthetic rendering. After determining the colour of the resin cement, the temporary crown was put back in place.

Fig. 4. Virtual model.

After glazing and preparation of the bonding surfaces in the dental laboratory, the upper veneers were cemented according to the PANAVIA™ Veneer LC protocol. We ended the session by removing excess cement. An occlusion check and postoperative photos were taken after three days.

DISCUSSION

In this case, the dental veneers and the crown on the implant were produced using a KATANA™ Zirconia UTML disc. This type of zirconia has an yttrium oxide proportion of 5 mol%, leading to about 70 % cubic zirconia phase, and therefore a higher translucency than earlier generations of zirconia. With a translucency of 51 % (light transmission, illuminant: D65, specimen thickness: 1.0 mm. Source: Kuraray Noritake Dental Inc); this zirconia allows us to have remarkable optical properties (fig 5).

Fig. 5. Remarkable optical properties of the final restorations.

The patient chose color BL1 and requested a transparent incisal edge. For this reason, a cutback design of the zirconia (fig. 6) and porcelain layering was the technique of choice. Figure 7 shows the slight transparency in the incisal edge region of the new restorations. The zirconia veneers technique was chosen to avoid the color difference between the crown on the implant and the veneers. The pleasant aesthetic appearance and a harmonious smile are confirmed by the post-operative picture (fig 8). According to the manufacturer, the flexural strength of KATANA™ Zirconia UTML is 557 MPa, which is higher than that of lithium disilicate and feldspathic porcelains. As zirconia veneers will be more resistant to shear forces, it is possible to eliminate contact points that interfere during try-in or even safely modify the shape of the restorations in vivo. This is done with specific burs adapted to zirconia during different stages of the fittings according to the wishes of the patient⁴.

Fig. 6. Cutback design of the restorations.

Fig. 7. Slight transparency at the incisal edges of the restorations.

Fig. 8. Immediate post-operative picture.

In the present case, we were able to adjust the crown until we had a perfect anterior line. It was thus possible to optimize the inclination of the crown without replacing the dental implant, in just one week.

Given the significant shear resistance, the dental laboratory technician made zirconia dental veneers with an average thickness of 0.3 mm. Such a thin veneer requires less preparation of the dental tissue, which will be limited to enamel instead of extending into the dentin, where the adhesion value is lower due to its low chemical composition in minerals⁵.

The expected difficulty in bonding zirconia veneers is explained by the absence of a vitreous phase given the poor adhesion of the crystalline phase to the bonding cement. However, the desired surface modification can be achieved with a different procedure: tribochemical silica coating. It was used in the present case to improve the adhesion of the zirconia veneers to the resin cement system. Indeed, it was found in an in-vitro evaluation that the tribochemical preparation technique and the application of MDP provide an optimized adhesive interface⁶. In this study, dual-beam focused ion-beam technology followed by scanning electron microscopy were used to compare the resin/zirconia bonding interface with tribochemical preparation/MDP and the bonding interface between resin/zirconia without this preparation.

The tribochemical process consists of an aero-abrasion of the zirconia surface with particles coated with silica combined with a silane primer containing MDP. The phosphate ester groups of this silane bind to the surface oxides of the zirconia, and the methacrylate group makes covalent bonds with the resin matrix of the PANAVIA™ Veneer LC cement⁷.

In the present clinical cases, the KATANA™ Zirconia UTML veneers were abraded with silicon dioxide with the formula SiO2. As a primer, we chose CLEARFIL™ CERAMIC PRIMER PLUS (Kuraray Noritake Dental Inc.), because it contains the original MDP monomer, developed Kuraray Co., Ltd.⁸.

To clean the veneers before applying CLEARFIL™ CERAMIC PRIMER PLUS, KATANA™ Cleaner (Kuraray Noritake Dental Inc.) was used. The presence of saliva and residues from fittings can alter the interface with the resin cement, which presents a risk of bonding failure of Zirconia veneers⁹.

One of the most important challenges in this case was to be able to hide the greyish color of the implant abutment which was visible through the zirconia crown. To hide the gray of the abutment, a resin opaker was applied. These techniques combined with the PANAVIA™ Veneer LC white gave us an optimal result (figs. 9 and 10)¹⁰.

Fig. 9. Treatment outcome.

Fig. 10. New smile designed according to the individual desires of the patient.

CONCLUSION

KATANA™ Zirconia UTML veneers have better mechanical properties than conventional veneers, so that the zirconia veneers technique allows users to combine bridges, crowns and dental veneers without a noticeable difference in shade. It offers acceptable translucency and aesthetics according to our observation. The technique of bonding the zirconia veneers with PANAVIA™ Veneer LC combined with a tribochemical treatment and the application of MDP on the adhesion surfaces allowed for a secure bonding, while the dyschromia caused by the implant abutment was effectively concealed.

Dentist:

DR. BASSEM JAIDANE

Born in Sousse, Tunisia, on June 12, 1983, Dr. Bassem Jaidane obtained his Doctorate in Dental Medicine in 2010 at the Faculty of Monastir. He opened his own clinic in 2010, specializing in aesthetics and dental implants, as well as dental veneers. Omni-patrician and passionate about all areas of dentistry, he has also developed advanced knowledge in dental prosthetics: 3D design, ceramic layering, finishing and glazing of crowns, bridges and veneers…

Dr. Bassem Jaidane has therefore acquired a certain expertise on the different types of dental veneers, whether pressed ceramic veneers, machined veneers, layereded veneers with the cut-back technique and lumineers veneers, after having carried out numerous cases. in feldspathic and lithium disilicate veneers, Dr. Bassem Jaidane has become one of the pioneers of the technique of dental veneers on zirconia.

References

1. Restaurations esthétiques grâce à la technique du cut-back Par Fleur Nadal, Geoffrey Di Bacco, Julien Chesnot Publié le 01.06.2019. Paru dans L‘Information Dentaire n°23 – 12 juin 2019 (page 28-29).
2. Effects of ceramic layer thickness, cement color, and abutment tooth color on color reproduction of feldspathic veneers Christopher Igiel, Michael Weyhrauch, Barbara Mayer, Herbert Scheller, Karl Martin Lehmann PMID: 29379907 Int J Esthet Dent 2018;13(1):110-119.
3. Influence of Air-Particle Deposition Protocols on the Surface Topography and Adhesion of Resin Cement to Zirconia. Acta Odontol: Sarmento, H.R.; Campos, F.; Sousa, R.S.; Machado, J.P.B.; Souza, R.O.A.; Bottino, M.A.; Ozcan, M: Acta Odontol Scand . 2014 Jul;72(5):346-53.doi: 10.3109/00016357.2013.837958. Epub 2013 Oct 31.
4. Comparison of the Mechanical Properties of Translucent Zirconia and Lithium Disilicate:Kwon, S.J.; Lawson, N.C.; McLaren, E.E.; Nejat, A.H.; Burgess, J.O. J.Prosthet:: J Prosthet Dent . 2018 Jul;120(1):132-137. doi: 10.1016/j.prosdent.2017.08.004. Epub 2018 Jan 6.
5. The Success of Dental Veneers According To Preparation Design and Material Type:Yousef Alothman, Maryam Saleh Bamasoud: Open Access Maced J Med Sci. 2018 Dec 14;6(12):2402-408.doi:10.3889/oamjms.2018.353. eCollection 2018 Dec 20.
6. The Effect of Resin Bonding on Long-Term Success of High-Strength Ceramics: Blatz, M.B.; Vonderheide, M.; Conejo, J: J Dent Res 2018 Feb;97(2):132-139. doi: 10.1177/0022034517729134. Epub 2017 Sep 6.
7. Ultra-thin monolithic zirconia veneers: reality or future? Report of a clinical case and one-year follow-up: Rodrigo Othávio Assunção Souza, Fernanda Pinheiro Barbosa, Gabriela Monteiro de Araújo, Eduardo Miyashita, Marco Antonio Bottino, Renata Marques de Melo, and Yu Zhang :Oper Dent :2018 ;43(1) :3_11.doi :10.234/16-350-T.
8. Functional monomer impurity affects adhesive performance :Kumiko Yoshihara 1 , Noriyuki Nagaoka, Takumi Okihara , Manabu Kuroboshi, Satoshi Hayakawa, Yukinori Maruo, Goro Nishigawa, Jan De Munck, Yasuhiro Yoshida, Bart Van Meerbeek : Dent Mater : 2015 Dec;31(12):1493-501.doi: 10.1016/j.dental.2015.09.019. Epub 2015 Oct 28.
9. Effect of decontamination materials on bond strength of saliva-contaminated CAD/CAM resin block and dentin Kei Takahashi, Tomohiro Yoshiyama, Akihito Yokoyama, Yasushi Shimada, Masahiro Yoshiyama : Dent Mater J 2022 Jul 30;41(4):601-607. doi: 10.4012/dmj.2021-268. Epub 2022 Apr 13.
10. Masking ability of implant abutment substrates by using different ceramic restorative systems Pablo Machado Soares , Ana Carolina Cadore-Rodrigues , Maria Gabriela Packaeser , Atais Bacchi , Luiz Felipe Valandro , Gabriel Kalil Rocha Pereira , Marília Pivetta Rippe J Prosthet Dent 2022 Sep;128(3):496.e1-496.e8. doi: 10.1016/j.prosdent.2022.05.010. Epub 2022 Aug 16. Affiliations PMID: 35985853 DOI: 10.1016/j.prosdent.2022.05.010.

Article by Michael Braian DDS, CDT, PHD

Digital advancements revolutionized dentistry, providing efficient, precise dental care¹. Intraoral scanners replace traditional impressions, enabling virtual models for procedures like implant placement, orthodontics, and prosthodontics². Scan bodies aid in digitizing implants, while CAD/CAM improves prosthesis design and fabrication³. Milling and 3D printing offer speed, accuracy, and complexity in creating dental prostheses⁴. These innovations promise a bright future for dental professionals and patients.

The integration of digital technologies in dentistry has brought about significant advancements in dental care1. This case study presents a comprehensive dental rehabilitation of a patient utilizing a digital workflow, including extraction, dentures, implant surgery, intraoral scanning, 3D printed try-ins, and the fabrication of the final monolithic prosthetic construction.

EXTRACTION OF SEVERELY DECAYED TEETH

The first step in the patient‘s dental rehabilitation involved the extraction of severely decayed teeth. This procedure was necessary to eliminate the source of infection and discomfort and to prepare the oral cavity for the subsequent steps in the rehabilitation process. The dentures are later used to simplify the guided surgery planning⁵. Following the extraction, the patient was provided with appropriate postoperative care instructions and a healing period was allowed before proceeding with the next steps (Fig.1).

Fig. 1. Severely decayed teeth prior to extraction.

DENTURES DURING THE HEALING PERIOD

During the healing period of approximately seven months, the patient was fitted with dentures to replace the extracted teeth. This temporary solution allowed the patient to maintain oral function, appearance, and confidence while the extraction sites healed, and the oral tissues prepared for the implant surgery⁶.

IMPLANT SURGERY

In the upper jaw, six implants were placed, while only four were placed in the lower jaw (Fig.2). This decision was based on the patient‘s individual needs and oral anatomy. Studies have shown that the number of implants required for optimal support and stability depends on various factors, including bone quality and quantity, implant position, and prosthesis design⁷. Research suggests that six implants in the upper jaw and four in the lower jaw are sufficient to provide adequate support for a full-arch fixed prosthesis, with high success rates and patient satisfaction reported⁷. Additionally, placing fewer implants can help reduce surgical time and cost, as well as minimize the risk of complications associated with multiple implant placements. Therefore, this approach was deemed appropriate for this particular patient‘s case.

LabLine magazine is an English language publication catering to the field of lab-side dentistry. It provides comprehensive coverage of the latest techniques and trends in dental laboratory technology and materials, showcasing them via sophisticated, challenging and aesthetic clinical cases done by some of the most known experts in Europe. With its expertly curated content, LabLine serves as an invaluable resource for dental professionals seeking to enhance their knowledge and stay at the forefront of the industry.

In the SPRING edition of LabLine you can find a wonderful AESTHETIC CASE by Mikel Villar Gonzales and DT Pilar Ballesteros Galan. The patient, a 21-year-old female had a hypoplasia defect on her permanent teeth, 1.1 and 1.2., presumably due to trauma on her deciduous anterior teeth. Click the image below and check out how the case was done!

The 46^th congress of European Prosthodontic Debates, also known as EPA2023, will take place in Vilnius, Lithuania 14-16^th of September, 2023.

It stands as a pinnacle gathering for dental professionals and researchers in the field of prosthodontics. This highly anticipated event serves as a platform to exchange knowledge, share insights, and engage in lively discussions on the latest advancements, achievements and challenges in prosthodontics.

EPA2023 promises to be an extraordinary occasion, attracting more than 50 experts from across Europe and beyond. Renowned speakers will present the newest advances in clinical prosthodontics and restorative dentistry. Daniele Rondoni, Matthias Kern, Nicola Scotti and Kazuyoshi Baba are only some of experts at the event; check out complete speaker line-up on the website www.epa2023.lt.

The event will feature thought-provoking debates, where experts will engage in intellectual discourse on current topics of prosthodontics, stimulating a lively exchange of ideas and perspectives. Special attention will be given to the successful application of digital solutions.

Beyond the scientific program, EPA2023 will provide ample opportunities for networking and collaboration. Attendees will have the chance to interact with colleagues, forge new partnerships, and establish connections with industry leaders, further enriching their professional networks.

As the European Prosthodontic Debates event continues to push the boundaries of prosthodontics, EPA2023 is expected to be a landmark occasion, empowering dental professionals to advance their knowledge, skills, and expertise in the ever-evolving field of prosthodontics.

Register now for EPA2023: www.epa2023.lt

Shortly before KATANA™ Zirconia ML was launched at the IDS in Cologne ten years ago, I had the pleasure to be invited to Japan. We visited the KATANA™ Zirconia production facilities and learned from Kazunobu Yamada and Takuro Nagura how the new material worked. So far, all dental zirconia I had used was white and quite opaque.

I was immediately impressed by the complexity of the production procedure including all the measures taken by Kuraray Noritake Dental to provide for an extremely high material and blank quality. The blanks appeared to have an extremely homogeneous multi-layered structure and a high density responsible for stable edges and smooth surfaces. What we were told in the manufacturing plant was confirmed by Kazunobu Yamada, who shared his experience and showed us several full-contour cases. I was pleasantly surprised by the fact that he was able to produce impressive outcomes without adding any colour. Moreover, Kazunobu Yamada was obviously able to polish the surface of his restorations within seconds. The perfectly smooth surface would allow us avoid the use of glaze, which usually wears off very quickly, leaving a potentially rough surface that may harm the antagonist.

Based on what I had learned in Japan, I went back to Italy and started experimenting with the amazing new material. While Kazunobu Yamada had identified KATANA™ Zirconia ML as the solution for monolithic restorations in the posterior area, I started using it in every region of the mouth – with different design concepts from full-contour to micro-cutback with micro-layering in the vestibular area. The occlusal contact area was always held in plain, polished zirconia.

Fig. 1. Early example of anterior restorations made of KATANA™ Zirconia ML individualized with CERABIEN™ ZR using the new micro-layering technique.

Fig. 2. Possible cutback design.

During the testing period, I learned a lot about the new zirconia, which was so different from earlier generations. The most important insight was that that the processing conditions have a huge impact on the final outcome. Kuraray Noritake Dental provided valuable support e.g. in the form of sintering protocols and processing and finishing recommendations. This helped me develop my own workflow and concept based on a full-contour design in the posterior and different micro-cutback options with micro-layering in the anterior region. For me, this is a perfect combination of the new type of zirconia (KATANA) and the traditional porcelain material (CERABIEN™ ZR Luster Porcelain and Internal Stain).

In May 2013, at a meeting of the Noritake Study Club in Florence, Italy, I presented the new approach for the first time. Many colleagues were enthusiastic about it and started adopting it. While further developments like more translucent (cubic) material variants and a new generation multi-layered zirconia with a flexural strength and translucency gradient increased the application options and aesthetic potential, micro-layering became a truly popular approach used by dental technicians all over the world. In 2016, it was recognized as a relevat workflow during a closed meeting of the European Academy of Aesthetic Dentistry.

Fig. 3. Perfectly polished palatal zirconia surfaces of anterior restorations.

Fig. 4. More recent case showing a patient who received restorations made of KATANA™ Zirconia STML …

Fig. 5. … finished with CERABIEN™ ZR Internal Stains and a micro-layer of CERABIEN™ Luster Porcelain LT1.

But what is the major reason for the success of the concept and of multi-layered zirconia with KATANA™ Zirconia ML as the pioneer? In my opinion, it should not be implemented for greater simplicity or economic reasons, as one might assume at first thought. The time saved in the layering procedure should be spent on other tasks such as surface texturing and a fine-tuning of the processing procedure. The real benefit is that KATANA™ Zirconia ML and its successors allow for better solutions adapted to the patient’s needs. First of all, they enable us to save natural tooth structure, as the required wall thickness is reduced. They also offer mechanical advantages, as chipping is avoided, and the occlusal contact area remains smooth over time. In my dental laboratory, we changed our workflows completely and – preferring a more conservative approach whenever indicated for the case on hand – we often abandon full layering.

KATANA™ Zirconia can be considered as a great contribution to the digital workflow in the dental laboratory and office, which increases the efficiency of prosthodontic procedures. With the KATANA™ Zirconia Multi-Layered series, it is easy to hold our promise of delivering the best possible quality and aesthetics. The reason is that the materials support us in an ideal way, delivering the perfect combination of tradition and innovation.

THE COMBINATION OF EFFECT LIQUIDS AND MICRO-LAYERING ON HIGHLY AESTHETIC ZIRCONIA IS THE EFFECTIVE WAY TO ACHIEVE OUTSTANDING RESULTS

Case by Leonidas Dimitriou, MDT

As an addition to its well-aligned portfolio of multi-layered zirconia (KATANA™ Zirconia Multi-Layered series) and veneering porcelain for zirconia (CERABIEN™ ZR), Kuraray Noritake Dental Inc. has recently introduced a set of dyeing liquids. Esthetic Colorant for KATANA™ Zirconia is applied to the surface of the monolithic or anatomically reduced zirconia restoration prior to the final sintering procedure. In this way, it is possible to imitate typical internal colour effects of natural teeth quite easily. Depending on the desired outcome, users may add just a final layer of glaze, liquid ceramics or stains and porcelains to their zirconia restorations treated with Esthetic Colorant. The following two case examples are used to demonstrate two different procedures involving the use of the effect liquids.

CASE EXAMPLE 1

In the first case, we produced three two-unit splinted crown restorations for six maxillary anterior teeth. The zirconia crowns (made of KATANA™ Zirconia YML) were anatomically reduced and individualized with Esthetic Colorant mainly in the incisal and cervical areas immediately after milling. For the application of the selected liquids, we used the Liquid Brush Pen specifically developed for Esthetic Colorant. The restorations were dried for half an hour, placed in the sintering furnace for sintering according to the recommended protocol for KATANA™ Zirconia and subsequently finished with CERABIEN™ ZR porcelains. Finally, CERABIEN™ ZR Paste Stain Glaze was applied for the final high-gloss finish.

Fig. 1. Pre-sintered anatomically reduced crowns after milling.

Fig. 2. Esthetic Colorant applied to the milled restorations.

Fig. 3. Appearance of the individualized restorations after the final sintering procedure.

Fig. 4. Restorations after porcelain layering.

FINAL SITUATION

Fig. 5. Final restorations with a natural appearance. The effects created with Esthetic Colorant shine from deep within the restorations.

Fig. 6. Lateral view of the final restorations from the left.

Fig. 7. Lateral view of the final restorations from the right.

CASE EXAMPLE 2

In this second case, two three-unit restorations were produced using KATANA™ Zirconia YML in the colour A3. We designed and milled them in full contour, then reduced them with hand instruments by 0.2 mm and added some texture effects to the surface before applying Esthetic Colorant. In this case, we played with different shades of Esthetic Colorant. Even when applied on a minimally reduced or monolithic surface, the liquids are able to create a nice depth effect as they diffuse into the zirconia structure. The amount of liquid applied is easily controlled with the Liquid Brush Pen, so that the intensity of the colours is predictable. After sintering, we added some internal stains, CERABIEN™ ZR Luster Porcelain and a final layer of CERABIEN™ ZR FC Paste Stain Glaze to finish the restorations. The outcome speaks for itself.

Fig. 8. Milled monolithic restorations with a pronounced surface texture.

Fig. 9. Vestibular and palatal surfaces individualized with Esthetic Colorant to create and intensify some natural colour effects.

Fig. 10. Appearance of the restorations immediately after sintering.

Fig. 11. Restorations after internal staining.

Fig. 12. A layer of luster porcelain applied to the minimally reduced restorations.

FINAL SITUATION

Fig. 13. Final outcome after glazing.

Dentist:

LEONIDAS DIMITRIOU, MDT

Interview with Yoshihisa Yamada
General Manager, Technology Division of Kuraray Noritake Dental Inc.

KATANA™ Zirconia ML was introduced ten years ago, at the IDS 2013 in Cologne, as the dental industry’s first zirconia product with a multi-layered colour structure. Since that event, KATANA™ Zirconia ML blanks have become very popular. Continued development efforts have led to the current line-up of multi-layered materials, KATANA™ Zirconia UTML, STML and HTML PLUS, and our latest product – KATANA™ Zirconia YML. Our new technology with colour, translucency and strength gradation is found in KATANA™ Zirconia YML.

Photo credits to MDT Giuliano Moustakis.

How important was the invention of the Kuraray Noritake Dental’s original multi-layered technology for the dental market?

Our impression is that the material has had a significant impact on the dental market. Being the first zirconia material with a multi-layered colour structure, KATANA™ Zirconia ML was our first product of its class to offer the properties needed for the efficient production of full-contour zirconia restorations with a natural look. Before its introduction, the “full-contour zirconia” concept had not been widely accepted due to the aesthetic properties of the zirconia materials available so far: Many of them lacked the desired level of translucency, while others needed to be treated with dyeing liquids or stains in a complex procedure to obtain a natural shade appearance. With the launch of multi-layered zirconia blanks, which successfully added natural colour gradation to the structure, aesthetic full-contour zirconia restorations started to become popular among dental technicians worldwide. The high potential of the technology was confirmed at the IDS 2013 show, when we saw not only end-users, but also engineers from competing companies come to look at this product.

4-layer colour structure of KATANA™ multi-layered discs.

Photo credits to MDT Daniele Rondoni.

What changes were driven forward by the introduction of KATANA™ Zirconia ML?

After the introduction of KATANA™ Zirconia ML, many companies started developing multi-layered zirconia discs, creating a new dental product category with an added technical and clinical value. We are convinced that the invention of Kuraray Noritake Dental has played a major role in the shift from zirconia exclusively used as a framework material to alternative approaches including full-contour zirconia restorations. If only monochromatic zirconia discs had been available, we imagine that an increased number of dental technicians would have embraced the concept of using liquid colourants to achieve a natural appearance of full-contour crowns and bridges. That would have prevented monolithic zirconia restorations from becoming as popular as they are today.

How did the KATANA™ Zirconia ML technology evolve over the past ten years?

Based on our unique core technology developed for inventing KATANA™ Zirconia ML, we have been continuing making efforts to create even better products. One of Kuraray Noritake Dental’s great strengths is its ability to develop all the raw materials for its zirconia products inhouse. This makes it possible for us to adjust the boundaries between the layers as inconspicuously as possible, even when discs consist of multiple layers. This enabled us to provide multi-layered discs with the required strength and aesthetic qualities, and with a stable, predictable shrinkage rate. In the past ten years, we have focused on adding new materials with different levels of translucency and strength to offer a portfolio that meets the demands of virtually every dental technician, practitioner and patient.

For example, the advent of KATANA™ Zirconia STML, which has even better aesthetic qualities than KATANA™ Zirconia ML, has made it possible to use it all by itself to create highly aesthetic restorations, with no need to characterize or individualize the restorations. Of course, if you use KATANA™ Zirconia Multi-Layered discs and treat the restorations with a surface staining agent, such as CERABIEN™ ZR FC Paste Stain, you can create even more aesthetic restorations in a shorter time.

What are the benefits of Kuraray Noritake Dental’s multi-layered technology, as compared with other manufacturer’s solutions?

KATANA™ Zirconia multi-layered discs offer the advantage of delivering the proper colour even when they are sintered at high speed. There are two reasons for this. First, we developed unique raw materials with suitable characteristics for high-speed firing. This allows the creation of restorations with the same strength, stability, and aesthetics to be achieved after both short- and long-time firing. The second reason is that we possess the technical know-how concerning excellent shading that Noritake Dental Supply, one of Kuraray Noritake Dental’s predecessors, cultivated during its many years spent developing ceramic materials. Noritake Co., Ltd., parent company of Noritake Dental Supply, is a long-established ceramic manufacturer that is famous for its tableware and other outstanding products. It is this background that allows us to properly control pigment coloration using our inorganic pigment know-how and to provide unique firing schedules. These two strengths enable us to bring unique advantages to our products. That is, they remain stable and retain appropriate colouration even under rapid firing schedules.

CERABIEN™ ZR FC Paste Stain being applied to KATANA™ Zirconia restoration.

Photo credits to MDT Roberto Rossi.

How did you manage to shorten the sintering times so significantly, resulting in your speedy sintering with uniform protocols?

When shorter sintering times became possible, Kuraray Noritake Dental recommended that KATANA™ Zirconia ML be sintered for seven hours. After that, when a new furnace claiming being capable of short-time firing was launched, we used it to fire KATANA™ Zirconia ML on a trial basis. We found, happily, that our zirconia material was uniquely compatible with rapid firing. This was the beginning of our full-fledged study of short-time firing of our zirconia material. You could say that we began investigating short-time firing almost by accident. Then, while developing KATANA™ Zirconia STML and KATANA™ Zirconia UTML, successors of KATANA™ Zirconia ML, we focused on incorporating short-time firing into their features and made various adjustments, finally achieving the optimal combination of factors for the successful short-time firing of zirconia.

What are the benefits of Kuraray Noritake Dental’s second-generation multi-layered technology, as compared with other manufacturer’s solutions?

One advantage of KATANA™ Zirconia YML is that it can be applied to treat a wider range of cases without complex limitations on position within the disc. The reason: it delivers this high level of aesthetics while still maintaining great strength. This advantage of being appropriate for a wider range of cases also simplifies inventory management. In addition, users benefit from our expertise in developing raw materials and reproducing colour with ceramics. This expertise enabled us to develop a zirconia product in which each layer has a different level of translucency, while great strength and admirable aesthetics are maintained throughout the whole blank.

The sintering recommendation is only a guideline; some adjustments may be required depending on each individual furnace. If the furnace cannot be set according to the 54- or 90-minute sintering schedule, speed sintering cannot be used.

* The restorations may be removed at 800°C or less depending on the circumstances.
** For the sintering schedule of KATANA™ Zirconia HT, please refer to the Handy Chart in product packaging.

Is it really possible to address every case using only KATANA™ Zirconia YML?

For every case that can be treated either with KATANA™ Zirconia STML, KATANA™ Zirconia UTML, or KATANA™ Zirconia HTML PLUS, KATANA™ Zirconia YML is also an option. Hence, it is possible to use only KATANA™ Zirconia YML for all your zirconia cases – which is probably one of the reasons for its great popularity. It features both great strength and excellent aesthetics, and – being so versatile – it helps simplify inventory management. Of course, Kuraray Noritake Dental’s other multi-layered materials feature outstanding properties as well. Depending on the features you need, it would also be an option to select from these products - KATANA™ Zirconia STML, KATANA™ Zirconia UTML, or KATANA™ Zirconia HTML PLUS – to realize your ideal restorations.

KATANA™ Zirconia YML, finished with CERABIEN™ ZR.

Photo credits to MDT Giuliano Moustakis.

Why is the KATANA™ brand in general so popular among dental technicians around the world?

We think that dental technicians choose KATANA™ because they find that they can create highly aesthetic restorations using simple, straightforward steps.

Is there any further development potential in multi-layered technology?

On the basis of our technical know-how, there is always room for improvement. That is why we never stop innovating and listening to the voice of our customers. Developing what supports them in improving their outcomes while providing for more predictable, less stressful procedures is our ultimate goal. Right now, we expect to develop products with even greater strength, increased translucency, and outstanding aesthetics that will have a natural look resembling real teeth, even when the material used is full-contour zirconia.

Dentist:

YOSHIHISA YAMADA

JUST COLOR: ESTHETIC COLORANT FOR KATANA ZIRCONIA

The natural tooth impresses with wonderful light-optical effects - characteristic features that result from the inner structure of the tooth. Imitating these specific effects in zirconia restorations with the staining technique or micro-layering has shown limitations so far. Kuraray Noritake has addressed this problem. Based on solid research and development work, an amazingly simple solution was created - Esthetic Colorant for KATANA Zirconia.

Mr. Stratos Chatzichristos CDT will present Esthetic Colorant in detail in this online webinar. He will show how the aesthetically individual effect of a zirconia restoration can be intensified with the new effect liquids and will showcase practical application and material science basics. Learn how to achieve a zirconia restoration with truly impressive aesthetics.

Topics:

•    basics about Esthetic Colorant for KATANA Zirconia
•    differences to traditional staining and infiltration solutions
•    areas of application of Esthetic Colorant
•    achieving a true color effect
•    masking effect for the zirconia framework (discolored stumps or metallic abutments)
•    economic advantages of using Esthetic Colorant
•    material basics of zirconia

According to Koelnmesse, 120,000 visitors from 162 countries attended the 40th International Dental Show between March 14 and 18, 2023. Being one of the 1,788 companies from 60 countries exhibiting at the show, the Kuraray Noritake Dental Inc. team enjoyed being back on-site, and seized every opportunity to connect with end-users of their products in person again. About 60 percent of the visitors and 75 percent of the exhibitors came from abroad. A highly international, euphoric atmosphere and lots of positive feedback on innovations confirmed that the team is on the right track in developing solutions that support users in improving the lives of their patients. However, the visiting dental professionals were not only interested in products for the dental office and laboratory, but also in smart techniques and approaches for their productive use – presented by renowned experts in lectures and hands-on demonstrations.

Laboratory solutions: The professionals were particularly interested in the brand-new Esthetic Colorant and the whole KATANA™ Zirconia Multi-Layered Series.

Hands-on demonstration of MDT Giuliano Moustakis: Zero Bake Technique with Esthetic Colorant and CERABIEN™ ZR FC Paste Stain.

MDT Nondas Vlachopoulos revealing how to obtain aesthetic outcomes with the One-Bake Technique.

Micro-layering with MDT Daniele Rondoni.

A roadmap to white-pink aesthetics shared by MDT Andreas Chatzimpatzakis.

MDT Alek Aronin describing a handcraft approach to highly aesthetic outcomes.

Indirect workflow solutions: PANAVIA™ Cements meeting every need.

Universal Excellence: CLEARFIL MAJESTY™ ES-2 Universal put to a test.

Handling test with direct restorative materials.

Demonstration of the flowable injection technique by Dr Michał Jaczewski.

Dr José Ignacio Zorzin shedding light on how to achieve reliable adhesion with universal products.

CEREC tips and tricks from MUDr Josef Kunkela, PhD.

Looking forward to seeing you at the next International Dental Show in Cologne in 2025 or elsewhere: The Kuraray Noritake Dental team!

A strong and durable bond between the tooth and the restoration is a decisive factor influencing the long-term performance of dental restorations. The quality of the bond, however, is not only affected by the bonding agent or cementation solution used, but also by the condition of the bonding surface. For those who would like to ensure clean tooth and restoration surfaces in an easy way, Kuraray Noritake Dental has developed KATANA™ Cleaner, a universal cleaner with MDP salt and a pH of 4.5 for intra- and extra-oral application.

It has been proven that proteins present in saliva and blood have a negative effect on the performance of dental adhesives. Especially in indirect procedures, however, it is impossible to keep the bonding surfaces free of oral fluids. At try-in at the latest, the prepared tooth and the restoration are contaminated and need to be cleaned. Rinsing with water does not have the desired effect, and even with many available cleaners, a certain amount of proteins are usually left on the surface. Tests show that by using KATANA™ Cleaner or by sandblasting, the desired high cleaning effect needed is obtained, without compromising bond strength. This is true for KATANA™ Zirconia restorations, while KATANA™ Cleaner also leads to the desired results on dentin and enamel – surfaces in the oral cavity for which sandblasting and most of the other cleaners are not indicated.

The use of KATANA™ Cleaner offers yet another advantage: the cleaning procedure is extraordinarily simple, quick and neat. The universal cleaner comes in a bottle with an innovative flip-top cap, enabling single-handed dispensing onto the dish. It is then rubbed into the surface of the restoration and the prepared tooth structure or the abutment for ten seconds, rinsed with water and dried. Thanks to the high surface activity of MDP salt, these ten seconds are sufficient to remove the proteins on the substrate almost completely, creating conditions very similar to those found on a non-contaminated bonding surface. Subsequently, the selected bonding agent or cementation solution – e.g. PANAVIA™ V5 or PANAVIA™ SA Cement Universal – is applied according to the maufacturer’s usage instructions.

The result is a strong long-lasting bond, which gives users a peace of mind. Pilot users who have already tested the product agree that KATANA™ Cleaner is the easy way to optimise bond quality and streamline any adhesive procedure.