KATANA™ Zirconia STML is a highly popular material used in many dental laboratories around the world. Compared to traditional zirconia framework materials with a mainly tetragonal polycrystalline structure, the material has a higher yttria content, leading to a different material structure with an impact on the optical and physical properties (the translucency is increased, the flexural strength reduced). As a consequence, the indication range is limited to single-tooth restorations and two to three-unit bridges in the anterior and posterior regions. The greatest benefit lies in a much higher aesthetic potential, which is responsible for the fact that the material is predominantly used for the production of monolithic restorations or those with a micro cut-back individualized with a micro-layer of porcelain.

While the indications and technical procedure are wellknown, there seem to be some obscurities regarding the handling in the dental office. Is conventional cementation possible and recommended or is an adhesive luting procedure preferable? Is the surface pre-treatment the same as for tetragonal zirconia or is a different procedure required? And what may be expected regarding the longterm behaviour of KATANA™ Zirconia STML restorations? A close look into the available scientific literature provides some guidance.

DEFINITIVE PLACEMENT OF RESTORATIONS MADE OF KATANA™ ZIRCONIA STML

Conventional cementation or adhesive luting? In principle, both procedures are possible when the restoration to be placed has a retentive design. It is generally accepted that a full coverage crown provides sufficient retention for conventional cementation when the abutment tooth is at least 4 mm high and the convergence angle of the axial walls ranges between 6 and 12 or maximally 15 degrees (1,2). The reason is that the flexural strength of the material is higher than 350 MPa (3), the critical value for conventional cementation. As conventional cements are opaque and available in a single shade, however, the use of a (self-) adhesive resin cement may be preferable with all hightranslucency restorative materials for aesthetic reasons. Anyway, these products are mandatory whenever a macroretentive preparation design is not feasible or wanted. To sum up, the use of a self-adhesive or adhesive resin cement is preferable in many situations. An argument in favour of self-adhesive resin cements is the lower effort involved in their use. But what about the pre-treatment of the zirconia? No matter what type of dental zirconia is used, etching with hydrofluoric acid is ineffective due to the lack of glass matrix in the material. However, it is clear that surface modification is necessary to establish a strong and durable bond to any resin cement system4,5. The method generally recommended for high-strength zirconia is sandblasting with aluminium oxide particles or tribochemical silica coating4. The particle size should be small (≤ 50 μm) and the pressure low (about 1 bar) to avoid a weakening of the material’s mechanical properties (3,4). For lower-strength material variants, this risk of weakening the material seems to be higher (5), so that it becomes even more important to work with a low pressure and particle size (5-8). In the case of KATANA™ Zirconia, however, it was reported that “alumina-sandblasting significantly increased the biaxial flexural strength of KATANA™ STML.” (9) This means that proper sandblasting of restorations made of KATANA™ Zirconia STML did not affect the flexural strength of the material, which was even increased because of the specific properties of zirconia from Kuraray Noritake Dental.

Based on these findings, the following procedures are recommended for high-translucency zirconia:

OPTION 1
Aluminium oxide air-abrasion followed by the use of a selfadhesive resin cement containing 10-MDP (6)

OPTION 2
Tribochemical silica coating followed by silanization of the bonding surface (6)

As the dual-cure self-adhesive resin cement PANAVIA™ SA Cement Universal contains the Original MDP monomer and the long carbon-chain silane coupling agent (LCSi Monomer), it is suited for both procedures. PANAVIA™ SA Cement Universal is available in an automix syringe and a handmix system, which consist of a pastepaste formulation. One paste contains the Original MDP monomer in a hydrophilic monomer environment and the other contains the inactive LCSi Monomer in an environment of hydrophobic monomers. When extruding the pastes, they are mixed in the syringe’s mixing tip (automix) or dispensed on a mixing pad and mixed by hand (handmix). Afterwards, the material is simply applied to the intaglio of the restoration and the restoration is placed. Cleanup of excess cement is easiest after tack-curing (2 to 5 seconds).

DOES THIS WORK WELL IN THE CLINICAL ENVIRONMENT?

The best way to check whether the described procedure is successful in the clinical environment is by conducting a clinical study. This is exactly what a group of researchers from the University Complutense of Madrid, Spain, has done with the material combination KATANA™ Zirconia STML and PANAVIA™ SA Cement Universal (10). Within the framework of the prospective clinical trial, 30 posterior crowns made of KATANA™ Zirconia STML were placed in 24 individuals in need of posterior tooth restorations. The teeth were prepared as recommended for all-ceramic restorations, allowing for a wall thickness of approximately 1 mm (recommended minimum wall thickness of KATANA™ Zirconia STML for crowns in the posterior region: 1.0 mm). The restorations were sintered, characterized and glazed as recommended by the material manufacturer and subsequently tried in. Prior to cementation, the intaglio of the restorations was pre-treated with aluminium oxide particles (50 μm, 1 bar pressure) followed by ultrasonic cleaning. The use of PANAVIA™ SA Cement Universal also was in line with the manufacturer’s recommendations. A clinical evaluation of the crowns was performed after 6, 12 and 24 months using the California Dental Association (CDA) quality evaluation system. The parameters evaluated in this system are the surface and colour of the restorations, their anatomical form and the marginal integrity of the crowns. After 24 months, the success and survival rates were 100 percent. Regarding all three parameters, the crowns received a “satisfactory” (Score 3 or 4) rating, marginal integrity (the key parameter to judge the performance of the resin cement) received an “excellent (the highest possible Score 4) in all 30 cases.

CONCLUSION

The researchers concluded that “the excellent results obtained in this study suggest that the third-generation tooth-supported monolithic zirconia crowns in posterior regions seem to be a good alternative to metal-ceramic crowns, second-generation monolithic zirconia crowns, and veneered zirconia crowns. A long-term study is necessary to confirm this short-period study.” Hence, it seems that KATANA™ Zirconia STML and PANAVIA™ SA Cement Universal are a promising team, and that adhering to the recommended abovementioned protocols is likely to produce excellent results that are stable over many years.

References:
1 Edelhoff D, Özcan M. To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials: cementation. Clin Oral Implants Res. 2007;18 Suppl3:193-204. 2 Güth JF, Stawarczyk B, Edelhoff D, Liebermann A. Zirconia and its novel compositions: What do clinicians need to know? Quintessence Int. 2019;50(7):512-20. 3 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. 4 Comino-Garayoa R, Peláez J, Tobar C, Rodríguez V, Suárez MJ. Adhesion to Zirconia: A Systematic Review of Surface Pretreatments and Resin Cements. Materials (Basel). 2021 May 22;14(11):2751. 5 Mehari K, Parke AS, Gallardo FF, Vandewalle KS. Assessing the Effects of Air Abrasion with Aluminum Oxide or Glass Beads to Zirconia on the Bond Strength of Cement. J Contemp Dent Pract. 2020 Jul 1;21(7):713-717. 6 Chen B, Yan Y, Xie H, Meng H, Zhang H, Chen C. Effects of Tribochemical Silica Coating and Alumina-Particle Air Abrasion on 3Y-TZP and 5Y-TZP: Evaluation of Surface Hardness, Roughness, Bonding, and Phase Transformation. J Adhes Dent. 2020;22(4):373-382. 7 Alammar A, Blatz MB. The resin bond to high-translucent zirconia-A systematic review. J Esthet Restor Dent. 2022 Jan;34(1):117-135. 8 Soto-Montero J, Missiato AV, dos Santos Dias CT, Giannini M. Effect of airborne particle abrasion and primer application on the surface wettability and bond strength of resin cements to translucent zirconia. J Adhes Sci Technol, Online publication May 2022. 9 Inokoshi M, Shimizubata M, Nozaki K, Takagaki T, Yoshihara K, Minakuchi S, Vleugels J, Van Meerbeek B, Zhang F. Impact of sandblasting on the flexural strength of highly translucent zirconia. J Mech Behav Biomed Mater. 2021 Mar;115:104268. 10 Gseibat M, Sevilla P, Lopez-Suarez C, Rodríguez V, Peláez J, Suárez MJ. Prospective Clinical Evaluation of Posterior Third-Generation Monolithic Zirconia Crowns Fabricated with Complete Digital Workflow: Two-Year Follow-Up. Materials (Basel). 2022 Jan 17;15(2):672. (https://pubmed.ncbi.nlm.nih.gov/35057389/)

Case by Aleksandra Łyżwińska, Warsaw, Poland.

ABSTRACT

Indirect overlays are the contemporary restoration standard for posterior teeth with extensive hard tissue loss. They provide for cuspal coverage, which decreases the likeliness of coronal and/or root fracture. At the same time and in contrast to crowns, overlay preparations minimize the removal of sound tooth structure especially in the cervical region, which is a critical factor.¹ Modern dental resin composites allow for direct cuspal coverage in a single-visit appointment. The results of in-vitro studies suggest that these direct overlays are a suitable alternative to their indirect counterparts in specific situations.^2-6 The following case report is used to describe the direct restoration procedure by means of a maxillary right molar with an extensive, deep MOD lesion.

INTRODUCTION

In the context of treating a tooth with an extensive carious lesion, a biomechanical risk assessment should be performed. The primary method of reducing the likeliness of tooth fracture is treatment with a restoration that provides cuspal coverage. The contemporary gold standard for biomechanically compromised teeth are adhesively cemented overlays as an alternative to crowns.¹ Another option that does not involve labwork is a direct overlay restoration.^2-6 The direct approach is especially suitable for long-term temporization, which may be required during orthodontic treatment, for example.

Case by Dr. Yohei Sato, DMD, PhD, Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine, JAPAN and Dr. Keisuke Ihara, CDT, i- Dental Lab, JAPAN.

Fig. 1. The patient visited us with a chief complaint of a desire for improved esthetics of the maxillary right and left lateral incisors.

Fig. 2. A core fabricated from a diagnostic wax model was applied and the necessary clearances were determined.

Fig. 3. Since the teeth are microdonts, the preparation of each abutment was completed by simply exposing a fresh surface to be covered by the laminate veneers.

Fig. 4. A layer of porcelain was applied on the lithium disilicate glass substrate, to make a complete laminate veneer.

Fig. 5. After a trial fitting, the inner surface of the laminate veneer was cleaned with KATANA™ Cleaner. The inner surface was conditioned according to the prosthesis‘ IFU.

Fig. 6. Milling. CLEARFIL™ CERAMIC PRIMER PLUS was applied and dried to silane couple the restoration.

Fig. 7. After a trial fitting, KATANA™ Cleaner was applied to the abutment, and rubbed for more than 10 seconds. Then, it was washed off sufficiently (until the cleaner color had completely disappeared), and dried with compressed air.

Fig. 8. K-ETCHANT Syringe was applied and left for 10 seconds before water-washing and compressed air-drying.

Fig. 9. PANAVIA™ V5 Tooth Primer was applied and left for 20 seconds before compressed-air drying.

Fig. 10. PANAVIA™ Veneer LC Paste was applied to the inner surface of the laminate veneer.

Fig. 11. The laminate veneer was seated and the fit checked. Then, the excess cement was tack-cured (not more than 1 second at any one point) and removed. Finally, the restoration was light-cured and finished.

FINAL SITUATION

Fig. 12. This photo shows the laminate veneer restorations one month after placement. The morphology and color of the right and left lateral incisors have been improved, providing a good balance to the entire anterior dentition.

Elke natuurlijke tand heeft zijn eigen karakteristieke optische eigenschappen, die voortkomen uit de inwendige structuur. Kuraray Noritake Dental Inc introduceert Esthetic Colorant voor KATANA^TM Zirconia. Dit assortiment van kleurvloeistoffen trekt in de zirkoniumstructuur en voegt daarmee extra kleurkenmerken toe aan de prothese. Nog vóór de sinterprocedure worden daarmee de eerste karakteristieken van een restauratie gecreëerd. Zo wordt de basis gelegd voor een vlotte, gemakkelijke en uiteindelijke unieke afwerking van de prothese.

Esthetic Colorant is specifiek ontwikkeld voor de KATANA^TM Zirconia, als aanvulling op de effecten van de meerlaagse kleurstructuur van het materiaal. Het assortiment bestaat uit 12 kleurvloeistoffen, die zijn geoptimaliseerd om een afname in sterkte van het zirkonium te beperken en defecten te voorkomen. De vloeistoffen worden na het frezen eenvoudig aangebracht op de monolithische of anatomische restauratie met behulp van een metaalvrij borsteltje of penseelstift, bij voorkeur met een Liquid Brush Pen. De Esthetic Colorant trekt vervolgens in het zirkonium. De inwendige kleureffecten worden gefixeerd en komen na de afsluitende sinterprocedure volledig naar voren. Voor de afwerking kunnen verschillende technieken worden toegepast, waaronder polijsten, glazing en micro-layering. 

Het compacte Esthetic Colorant-assortiment omvat slechts 12 kleuren. Dat zorgt voor een overzichtelijker voorraadbeheer. De nieuwe Liquid Brush Pen voor Esthetic Colorant maakt het pakket af. Met deze pen houdt de tandtechnicus de toegepaste hoeveelheid kleurvloeistof volledig in eigen hand.

A discoloured abutment tooth, a metal post or tooth-coloured gum areas: It is not always possible to meet the target tooth or gum shade with a pre-shaded zirconia framework. Porcelain layering on a differently coloured base, however, is likely to deliver unexpected outcomes. The “CERABIEN™ ZR” Shade Base line-up has been developed and recently extended by Kuraray Noritake Dental Inc. for those who would like to avoid surprises and provide for a favourable framework colour, right from the start of porcelain layering. The five new opaque shades deliver approximately five times higher opacity than conventional “CERABIEN™ ZR” Shade Base porcelains, and can mask the base colour much more effectively for even more lifelike restorations.

The “CERABIEN™ ZR” Shade Base opaque shade line-up consists of three shades that reproduce tooth colour: Opaque White as a bleaching shade, Opaque Light as an A2 shade, and Opaque Dark as an A3.5 shade. They may be mixed or applied as delivered to the zirconia framework in thin layers to mask severely discoloured or metal areas. In most situations with a severely discoloured base, a precise matching of the target shade is achieved by applying an opaque shade as a first layer and a target-coloured “CERABIEN™ ZR” Shade Base as a second layer.

The other two new opaque shades – “CERABIEN™ ZR” Opaque Light Tissue and Opaque Dark Tissue – are used in a similar way to create a pink-opaque base in the gum areas of tooth-coloured zirconia frameworks (e.g. made of KATANA™ Zirconia Multi-Layered discs), which is perfect for reproducing gingival colour. Applied as a thin coating, the opaque tissue shades neutralise the tooth colour and their moderate reflection improves the colour effect of the subsequently applied tissue porcelains.

With their high masking ability, the new opaque shades make it even easier to adjust zirconia framework colours for highly aesthetic porcelain layering – no matter whether the base colour of a tissue or tooth area needs to be optimized.

Testimonial article by Dr. Michael Teitelbaum, DMD, MAGD, FACD

A self-adhesive resin cement that contains MDP and LCSi monomers, allowing it to adhere to virtually every material without the need for a separate primer.

Ready to say goodbye to complicated bonding procedures, Dr. Michael Teitelbaum said hello to simplicity with Kuraray Noritake Dental Inc.‘s PANAVIA™ SA Cement Universal, a versatile cementation solution that simplifies his restorative workflow without sacrificing long-term bond strength. “PANAVIA™ is a name I’ve known and trusted since my prosthodontic program over 30 years ago,” shared Dr. Teitelbaum, who said PANAVIA™ SA Cement Universal allows him to confidently cement restorations because of its long-term reliability.

ALL-IN-ONE CEMENTATION SOLUTION

A self-adhesive resin cement that eliminates the need for a separate primer, PANAVIA™ SA Cement Universal contains a unique LCSi monomer that delivers a strong, durable chemical bond to porcelain, lithium disilicate, and composite resin, while a MDP monomer chemically reacts with zirconia, dentin, and enamel. “When I find myself cementing zirconia, my go-to cement is PANAVIA SA™ Cement Universal because it contains MDP, the magic ingredient that lets it actually bond to zirconia,” Dr. Teitelbaum explained. Thanks to a single-step bonding formula, PANAVIA™ SA Cement Universal is an easy-to-use, all-in-one cementation solution, and the material is available in both automix and handmix options. “One of the nice things about PANAVIA™ SA Cement Universal is if you’re in a hurry, maybe doing multiple units or working alone, you can use the automixing syringe tip and inject it into each crown,” said Dr. Teitelbaum. “Or if you’re naturally fast, like my assistant of over 20 years, you can hand mix the cement and load it directly into the crowns.”

“My go-to cement is PANAVIA™ SA Cement Universal because it contains MDP, the magic ingredient that lets it actually bond to zirconia.”

- Michael Teitelbaum, DMD, MAGD, FACD –

VERSATILE AND EASY TO USE

PANAVIA™ SA Cement Universal adheres to virtually all restorative materials without the need for a separate primer, silane, or etchant, simplifying the cementation workflow for clinicians and saving time for patients. “I have a patient who not only gags but makes more saliva than the Colorado River,” joked Dr. Teitelbaum. “It was nearly impossible [with other cements] to keep No. 31 dry long enough to sandblast, etch, prime, mix cement, load the crown and seat it. PANAVIA™ SA Cement Universal was the only cement I could get to work for him.” After the restoration is placed, any excess cement is easy to clean up after a quick 2 to 5 second light cure. “Once you’ve fully seated the crown, you can wave the curing light over the margins for a couple of seconds to just start the set. The excess material easily pops off while still in the rubbery phase,” said Dr. Teitelbaum. PANAVIA™ SA Cement Universal comes in 3 shades, universal (A2), translucent and white, which Dr. Teitelbaum says are suitable for most situations. “For translucent restorations, like inlays where the margins might be visible, I prefer a translucent or universal shade cement,” he said. “But where I may need to see the cement again someday, like an opaque crown or post, I prefer straight white.” Suitable for crowns, bridges, inlays/onlays, posts, and adhesion bridges, PANAVIA™ SA Cement Universal is a versatile cementation solution for virtually every material.

Dentist:

MICHAEL TEITELBAUM
DMD, MAGD, FACD

Case by Richard Young DDS, San Bernardino, CA

Easy procedure, reliable outcome: that is what most dental practitioners may wish for when placing indirect restorations. The following clinical case example is used to demonstrate an easy, but highly successful clinical protocol for the luting of a lithium disilicate crown.

Fig. 1. Lithium disilicate crown after etching of the intaglio surface with hydrofluoric acid and try-in.

Fig. 2a. Application of KATANA™ Cleaner into the crown for a complete removal of contaminants such as proteins from blood and saliva, which may compromise the performance of any resin cement system.

OR Fig. 2b. Alternatively, KATANA™ Cleaner is applied into a mixing well.

Fig. 3. Application of KATANA™ Cleaner to the restoration.

Fig. 4. KATANA™ Cleaner is applied to the prepared tooth structure in the same way (rubbing for ten seconds followed by rinsing and drying).

Fig. 5. Application of PANAVIA™ SA Cement Universal into the cleaned crown.

Fig. 6. The cement contains a unique silane coupling agent – the LCSi monomer - for a strong and reliable bond to lithium disilicate and other restorative materials like glass ceramics and hybrid ceramics.

   The Silane is activated in the mixing tip by Original MDP.

Fig. 7. Easy clean-up after two to five seconds of tack-curing.

Fig. 8. The excess resin cement is in its gel-state and removed in one piece with an explorer.

FINAL SITUATION

Fig. 9. Treatment outcome immediately after crown placement.

Dentist:

RICHARD YOUNG DDS

Case and images courtesy of Richard Young DDS, San Bernardino, CA

Is it possible to reduce the number of different cements used in a dental office? In most cases, it is. Kuraray Noritake Dental Inc. is convinced that one or two resin cement systems are usually enough to cover every indication and every need for general cementation. The selection of products may be different depending on personal preferences and the focus on specific dental treatments.

That is why the company offers three high-quality resin cements, with which it is possible to meet the needs and desires of every dentist and patient. One product is available for those who would like to keep it as simple as possible while taking advantage of the multiple benefits resin cements offer over conventional cements. Another system is designed for those who demand highest possible bond strength and aesthetics. And finally, a light-curing system has been developed as a specialized solution for veneer cementation.

In order to facilitate decision making, this article provides in-depth information on each of the three systems and their specific strengths.

The everyday cement

Keeping cementation simple and efficient is possible by minimizing the number of work steps and components and solving existing challenges. The self-adhesive dual-cure resin cement PANAVIA™ SA Cement Universal has been designed for these purposes. The challenge of removing sticky excess cement is overcome by a formulation that allows for very easy excess clean-up.

Components are reduced as the product incorporates Kuraray Noritake Dental Inc.’s Original MDP Monomer and original silane coupling agent, the LCSi Monomer, for a strong and durable bond. While MDP establishes a strong and long-lasting chemical bond to enamel, dentin, metal and zirconia, LCSi is responsible for bonding to resin composite, porcelain and silica-type ceramics (like lithium disilicate), eliminating the need for separate primers.

This means that a single component is needed, which streamlines the procedure, leading to time savings and a minimized potential for errors. Due to its properties, PANAVIA™ SA Cement Universal is ideal for everyday procedures such as the permanent cementation of crowns and bridges made of zirconia, lithium disilicate, hybrid ceramic or even metal.

The strong and aesthetic allrounder

For those who place importance on achieving the highest possible bond strength and aesthetics, PANAVIA™ V5 is the solution. The reliable dual-cure cementation system consisting of a tooth primer, a cement paste and a ceramic primer produces the highest bond strength and aesthetics from the PANAVIA™ cement range.

Therefore, it is an excellent choice for a whole range of indirect restorations and for post-and-core procedures. As the well-aligned components are always combined and applied in the same way, standardization is supported, leading to predictable outcomes.

The veneer specialist

When fulfilling such demanding tasks as cementing veneers, every dental practitioner needs time. Especially when placing multiple veneers at once for the best aesthetic outcomes, having to race against the setting time is counterproductive. For this reason, Kuraray Noritake Dental Inc. developed PANAVIA™ Veneer LC, a light-curing resin cement system with an extended working time of 200 seconds* on the primer, which allows users to initiate polymerization whenever they are ready for it.

PANAVIA™ Veneer LC also offers a well-aligned paste viscosity and consistency for easy dispensing and seating, and comes in four highly colour-stable shades for long-lasting aesthetics. Finally, the system provides for easy excess removal after tack-curing and an excellent bond strength over time.

** Working time: sensitivity to light (8000 lux, ISO 4049)

Meeting expectations

The three products mentioned are precisely what is needed to cover every personal preference and specific indication. They are based on Kuraray Noritake Dental Inc.’s long-standing expertise in the development of adhesive resin cements. The first product from the PANAVIA™ brand was introduced in the 1980s and since then, the company never stopped improving the portfolio by combining existing technologies like the original MDP Monomer with newly developed ones, such as the LCSi Monomer and the Touch Cure Technology. All this ultimately resulted in the current lean portfolio of easy-to-use and highly aesthetic resin cements that provide top-level bond strength.

The prerequisite for adhesive luting is a reliable bond between the tooth and the restorative material. The quality of the bond depends on the resin cement and its correct application. The state of the bonding surface also plays a decisive role. The surfaces of the tooth and restoration must be conditioned and clean. We spoke with Dr. Adham Elsayed.

All-ceramic restorations require adhesive luting. Is this true for all restorative materials (zirconia, lithium disilicate, hybrid ceramics, etc.)?

Yes and no, several factors must be taken into account. The first important factor are the material properties, especially the flexural strength. Fortunately, clear guidelines based on scientific studies are available. As a guideline, all materials with a flexural strength of less than 350 MPa should be placed with an adhesively luted. Correct adhesive luting stabilizes the restoration and tooth structure. Restorative materials of higher strength (e.g. reinforced glass-ceramics, lithium disilicate ceramics, zirconia, etc.) can be cemented with conventional methods. However, some studies indicate that an adhesive luting can improve the overall stability, whereas others show no significant difference.

Another factor guiding the decision for or against adhesive luting is the preparation design. For crowns and bridges, the decisive factor is whether the operator has been able to adhere to the preparation guidelines (minimum abutment height of 4 mm and maximum convergence of 15 degrees)1-5 in order to create the required retention and resistance form for conventional cementation. Minimally invasive restorations, such as resin-bonded fixed dental prothesis (FDPs), veneers and inlay FDPs, are based on a non-retentive preparation design. In such cases, only adhesive luting can ensure adequate retention.

Aesthetics is another important factor. Besides the restorative material, the luting material also has a major impact on the optical outcome. For highly translucent ceramics in particular, it is recommended to resort to adhesive luting. While conventional cements are usually only available as opaque materials, resin composites come in different colours with higher colour stability (PANAVIA V5 or PANAVIA SA Universal).

How should the surface be pre-treated or conditioned for adhesive luting?

Pre-treatment of the surface depends on the structure or microstructure of the ceramic. Silicate ceramics (e.g. glass ceramics) have a glass phase and can be etched. Etching increases the surface area, thus preparing it for adhesive luting. In contrast, oxide ceramics like zirconia as well as composites have no or neglectable amount of glass phase. They cannot be etched. Their surface is conditioned by air-abrasion (with aluminium oxide). This is the only current method which is scientifically proven for achieving a dependable bond with these materials.

How important is correct cleaning of the tooth and restoration surface for the quality of the bond?

The restoration surface must be decontaminated immediately prior to luting. Contamination must be removed thoroughly. Rinsing with water or alcohol has been shown to be insufficient. Therefore, cleaning solutions such as KATANA Cleaner have been developed.

Rub it in, rinse and dry—that's all—for optimal bonding procedures. Unlike other cleaning products, which have to be rubbed in for longer and are only suitable for extraoral use due to their high pH value, KATANA Cleaner is applied within 10 sec. and is suitable for both intraoral and extraoral use.

Any contamination is detrimental for the adhesive bond. At try-in of the restoration, for example, its surface becomes contaminated. Saliva, possibly blood, etc. accumulate and the proteins contained act to isolate all subsequently applied components (e.g. the primer). Any contamination must therefore be thoroughly removed prior to the bonding procedure. This is also the case for direct adhesive restorations. KATANA Cleaner offers a simple and quick way to accomplish this task.

What makes KATANA Cleaner so interesting for the user?

The special features of KATANA Cleaner are its integrated MDP salt and mild pH-value. Let's look at the function of the MDP salt. Rubbed in (for 10 seconds), the cleaner causes the contaminant particles (e.g. remnants from the work process, proteins from saliva, blood, etc.) to adhere to the MDP salt, like a magnet. The contamination is flushed out of the surface by rinsing with water. This ability is attributable to the MDP salt and makes KATANA Cleaner interesting and easy to use. In addition, the pH-value allows us to use the cleaning solution both intraorally and extra-orally, which is another special feature. We generally recommend the use of KATANA Cleaner—for both direct and indirect restorations. Thanks to the universal applicability of the cleaning solution, only one material is needed, while the time required is extremely low. Even for bonding abutments on a titanium base, cleaning with KATANA Cleaner is recommendable as it provides for an ideal basis (before applying the primer). In this case, contamination (e.g. finger grease, residues of the air abrasive) could also act as an insulator and impair the quality of the bond.

References:

1. Ladha K, Verma M. Conventional and contemporary luting cements: an overview. J Indian Prosthodont Soc. 2010;10(2):79-88.
2. Edelhoff D, Özcan M. To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials: cementation. Clin Oral Implants Res. 2007;18 Suppl 3:193-204.
3. Güth JF, Stawarczyk B, Edelhoff D, Liebermann A. Zirconia and its novel compositions: What do clinicians need to know? Quintessence Int. 2019;50(7):512-20.
4. Smith CT, Gary JJ, Conkin JE, Franks HL. Effective taper criterion for the full veneer crown preparation in preclinical prosthodontics. J Prosthodont. 1999;8(3):196-200.
5. Uy JN, Neo JC, Chan SH. The effect of tooth and foundation restoration heights on the load fatigue performance of cast crowns. J Prosthet Dent. 2010;104(5):318-24.

How to condition ceramic surfaces prior to their cementation? And what are the parameters guiding the decision for adhesive, self-adhesive or conventional systems? Dr. Gerard Chiche and Prof. Dr. Markus B. Blatz know the answers. In this lecture, they shared exactly the knowledge needed to achieve predictable results.

October 7^th, 2022 marked the 10^th anniversary of the dental divisions of Kuraray and Noritake becoming Kuraray Noritake Dental Inc. For this celebration, ten internationally renowned experts shared their scientific, technical and clinical know-how in the virtual symposium titled “Up to now and from now on: From innovation to simplification”.

We prepared and uploaded the recording of this fifth and final lecture so you can watch it at your convenience.