Article by Dr. Adham Elsayed

High-performance adhesive resin cements are often the enablers of minimally invasive prosthodontic treatments. When the main aim is to save as much healthy tooth structure as possible, preparation designs that offer sufficient macro-mechanical retention for conventional cements are usually abandoned. The designs chosen instead need to rely on a strong and durable chemical adhesion established between the tooth structure and the restorative material – a task successfully accomplished by modern adhesive resin cement systems.

An excellent example of a minimally invasive, non-retentive preparation and restoration design is the single-retainer resin-bonded fixed dental prosthesis (RBFDPs), nowadays usually made of 3Y-TZP zirconia. With its single cantilever bonded to the oral and proximal enamel surface of an adjacent tooth, it requires minimal to no healthy tooth structure removal. The RBFDP is often used to replace a congenitally missing tooth – in many cases a maxillary lateral incisor – in young patients with incomplete dentoalveolar development and narrow edentulous spaces unsuitable for conventional implant placement¹ (Fig. 1 and 2). Additional factors hindering implant therapy – like an insufficient bone volume or angulated roots – are also not an issue for this type of restoration. And compared to orthodontic gap closure, the treatment approach with a RBFDP is less risky, as it does not affect the vertical jaw relationship, prevent canine guidance or compromise the aesthetic appearance². Finally, it is much less invasive than conventional FDPs, which is usually not a treatment option for young patients in the anterior region. The level of patient satisfaction and the success rates of this treatment approach are impressive^3-7.

Fig. 1-2. Replacement of both congenitally missing maxillary lateral incisors with single-retainer zirconia RBFDPs after soft tissue augmentation and gingival margin correction.

Despite the numerous advantages and excellent clinical performance – single-retainer RBFDP made of zirconia showed a survival of 98.2 percent and a success rate of 92.0 percent after ten years⁴ – many dental practitioners still opt for alternative treatment options. The reason may be a lack of trust in the bond strength and durability to zirconia. However, this bond can be very strong and durable – provided that a few rules are respected.

HOW TO ESTABLISH A STRONG BOND TO THE TOOTH STRUCTURE

In order to decide whether a missing tooth may be successfully replaced by a single-retainer RBFDP made of zirconia, the abutment tooth should be examined carefully. It needs to be vital and largely free of caries or direct restorations, while the oral enamel surface must be large enough for resin bonding¹. In addition, the space required for the placement of a retainer wing (thickness: about 0.7 mm) needs to be available, as a non-contact design is important for the success of the restoration. Among the preparation designs described in the literature is a lingual veneer and small proximal box preparation with retentive elements located in the enamel only¹, or no preparation at all⁷. For restoration placement, the abutment tooth is treated as usual: after cleaning e.g., with fluoride-free prophylaxis paste, phosphoric acid etchant is applied to the bonding surface, which is then thoroughly rinsed and dried.

HOW TO ESTABLISH A STRONG BOND TO THE RESTORATION

The recommended pre-treatment for the bonding surface of the retainer wing made of zirconia is small-particle (50 μm) aluminium oxide air-abrasion at a low pressure (approx. 1 bar)^8,9, followed by ultrasonic cleaning. Figures 3 (A-E) shows the sequence of surface treatment of zirconia restorations. As a visual aid for a controlled air-abrasion treatment, the marking of the surface with a pen has proven its worth. The whole air-abrasion procedure should be carried out after try-in, during which the tooth surface and the restoration usually becomes contaminated through contact with saliva and sometimes blood. Proteins present in saliva and blood that contaminate the bonding surface are safely removed in this way, while the required surface modification necessary to establish a strong and durable bond to the selected resin cement system is achieved¹⁰.

FIGURE 3: SEQUENCE OF SURFACE TREATMENT OF ZIRCONIA RESTORATION.

Fig. 3A. Cleaning of the restoration prior to luting with water steam cleaner.

Fig. 3B. Marking of the bonding surface as an visual aid for the air-abrasion.

Fig. 3C. Air-abrasion with 50-μm Al₂O₃ particles with 1 bar pressure.

Fig. 3D. Application of a primer containing 10-MDP.

Fig. 3E. Application of the composite resin cement.

WHICH RESIN CEMENT SYSTEM TO CHOOSE

Subsequently, the components of the resin cement system are applied. Regarding the selection of the system, it is generally recommended to use a restoration primer or resin cement that contains 10-Methacryloyloxydecyl dihydrogen phosphate (10-MDP)¹¹. In this way, a high-quality chemical bond is established. Among the resin cement systems used in the available long-term clinical studies is PANAVIA™ 21 (Kuraray Noritake Dental Inc.)^4-6. Launched in 1993, this anaerobic-curing adhesive resin cement contains several important technologies like the MDP monomer and the Touch Cure Technology found in PANAVIA™ V5, the state-of-the art dual-cure multi-bottle adhesive resin cement system of the company. In order to further improve the bonding performance of this present product, however, the team of developers reviewed the basic composition, updated existing technologies and combined them with completely new ingredients.

Even with PANAVIA™ 21 introduced 30 years ago, high success rates were obtained^4-6. The few observed failures were mainly due to chipping of the veneering ceramic or debonding. Sometimes caused by traumatic incidents, the debondings resulted in no further damage and the restorations were simply rebonded using the same cementation system and procedure.

One might expect that with its improved formulation, PANAVIA™ V5 will offer an even stronger and more durable bond than predecessor products, so that it is even better suited for such demanding applications as the resin-bonded fixed dental prosthesis. In a pilot study, this assumption was confirmed⁷. Without any preparation of the abutment tooth, but a defined size of the bonding surface of at least 35 mm², the team of researchers placed 24 monolithic zirconia resin-bonded bridges (made of KATANA™ Zirconia HT) to replace congenitally missing lateral incisors. The palatal sides of the central incisors were cleaned with pumice paste and treated with phosphoric acid, while the bonding surfaces of the restorations were sandblasted with aluminum oxide particles (50 μm, 2.5 bar pressure). Afterwards, twelve restorations were luted with PANAVIA™ V5, the other twelve with PANAVIA™ F2.0 (another earlier-version resin cement from Kuraray Noritake Dental Inc.). After an observation period of 32 to 50.47 months, the success and survival rates in the PANAVIA™ V5 group were 100 percent. In the other group, a connector fracture, a chipping and two debondings occurred. Based on these results, the authors of the publication concluded that “it has been seen that the new generation cement (PANAVIA™ V5) is more successful”⁷.

CONCLUSION

For many years, minimally invasive indirect restorative approaches like the replacement of missing incisors with resin-bonded fixed dental prostheses have been performed successfully by some dental practitioners. Many others, however, still seem to be hesitant whether these approaches will lead to the desired results in their hands. The available clinical study results, however, have confirmed that the procedure is highly advantageous and successful, while ongoing development efforts in the field of adhesive resin cements have led to products further decreasing the failure rates related to debonding. Even if a debonding occurs, however, no damage is usually done, so that the restoration can be rebonded again with little effort. These findings – together with the well-known benefits of minimally invasive dentistry in general – should encourage dental practitioners to start exploring the full potential of adhesive dentistry for themselves. In this context, PANAVIA™ V5 is definitely an excellent choice.

References

1. Sasse M, Kern M. All-ceramic resin-bonded fixed dental prostheses: treatment planning, clinical procedures, and outcome. Quintessence Int. 2014 Apr;45(4):291-7. doi: 10.3290/j.qi.a31328. PMID: 24570997.
2. Tetsch J, Spilker L, Mohrhardt S, Terheyden H (2020) Implant Therapy for Solitary and Multiple Dental Ageneses. Int J Dent Oral Health 6(6): dx.doi. org/10.16966/2378-7090.332.
3. Wei YR, Wang XD, Zhang Q, Li XX, Blatz MB, Jian YT, Zhao K. Clinical performance of anterior resin-bonded fixed dental prostheses with different framework designs: A systematic review and meta-analysis. J Dent. 2016 Apr;47:1-7. doi: 10.1016/j.jdent.2016.02.003. Epub 2016 Feb 11. PMID: 26875611.
4. 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. Epub 2017 Jul 5. PMID: 28688950.
5. Kern M. Fifteen-year survival of anterior all-ceramic cantilever resin-bonded fixed dental prostheses. J Dent. 2017 Jan;56:133-135.
6. Sasse M, Kern M. Survival of anterior cantilevered all-ceramic resin-bonded fixed dental prostheses made from zirconia ceramic. J Dent. 2014 Jun;42(6):660-3. doi: 10.1016/j.jdent.2014.02.021. Epub 2014 Mar 5. PMID: 24613605.
7. 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. doi: 10.1111/jerd.12945. Epub 2022 Aug 3. PMID: 35920051.
8. Kern M. Bonding to oxide ceramics—laboratory testing versus clinical outcome. Dent Mater. 2015 Jan;31(1):8-14. doi: 10.1016/j.dental.2014.06.007. Epub 2014 Jul 21. PMID: 25059831.
9. 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.
10. 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.
11. 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. doi: 10.1016/j.prosdent.2021.10.015. Epub ahead of print. PMID: 34893319.

A guideline with regard to contemporary materials

The retention of the fixed prosthodontic restorations is a critical factor for the long-term success, as the loss of crown retention is one of the main reasons for failure of crowns and fixed dental prosthesis (FDP) ^{(1, 2)}. There are three main elements that need to be considered to achieve proper retention of the restorations; the tooth preparation, the restorative material and the luting agent.

TOOTH PREPARATION

During tooth preparation there are some important features to be considered, such as the height, angle and surface texture of the abutment tooth, in order to achieve an adequate retention and resistance form which provide stability of the restorations to resist dislodgment and subsequent loss ⁽³⁾. Retention form is responsible for counteracting tensile stresses, whereas resistance form counteracts shear stresses ⁽⁴⁾.

In order to achieve a sufficient retention and resistance form for full coverage crowns it is recommended that the height of the abutment tooth should be at least 4 mm and that the optimal convergence angle should range from 6 to 12 degrees with a maximum of 15 degrees ^{(1, 5-8)}.

RESTORATIVE MATERIAL

With the continuous introduction of new restorative materials to the dental market it is important to take into consideration the different mechanical properties of the various materials. The composition and the surface properties of the material have a decisive role in the ability to accomplish mechanical and/or chemical attachment to the restoration and therefore achieving required retention.

LUTING AGENT

The luting agent is the connection between the tooth and the restoration. Proper luting of indirect restoration is critical in achieving long-term success as it highly influences the retention of the restoration as well as tightly sealing the gap between the restoration and the tooth. Although there are several classifications for the definitive luting agents, they can be , however, classified into two main categories based on the ability to achieve chemical connection to different substrates; conventional (e.g. zinc phosphate, glass-ionomer and resin-modified glass-ionomer cements) and adhesives. Most commonly used and best documented adhesive luting agents are the adhesive composite resin cements.

Composite resin cements can be further classified according to the chemical composition into traditional full-adhesive resin cement and self-adhesive resin cements, both also differ in the bonding procedure. The full-adhesive resin cements require pre-treatment of the tooth structure and restorative material using separate adhesive systems. In this combination of the resin cement and the adhesive system, very durable chemical bonding can be reached.

To simplify the luting procedure and eliminate the need of using several components, the self-adhesive resin cements are a good choice for the daily busy practice, in which reliable bonding can be achieved in only one simple step of cement application, mostly without additional primers or bonding agents.

With the availability of different types of cements, the decision of choosing the suitable luting agent and method can be confusing for the practitioner. Especially with the wide use of contemporary restorative materials such as new generations of highly translucent zirconia as well as reinforced-composites, it is important to take into consideration that the properties of such materials differ highly from metal or earlier generations of zirconia. Subsequently the choice of the luting agent must be appropriate to achieve satisfying results and long-term success. Therefore, in this article, the authors aim to provide insights for the clinicians on choosing the correct luting agent that can help achieve satisfactory results for the dentist as well as the patients.

CONVENTIONAL CEMENTATION OR ADHESIVE LUTING?

The choice of whether to use a conventional cement or an adhesive resin cement depends on several factors, the key factors are:

1. Retention and resistance form of the abutment tooth.
2. Mechanical and optical properties of the restorative material (flexural strength and translucency).
3. Simplicity of the workflow and special requirements of the working environment.

1) RETENTION AND RESISTANCE FORM OF THE ABUTMENT TOOTH

Minimal-invasive restorations, such as resin-bonded FDP, labial and occlusal veneers and inlay-retained FDP are based on a non-retentive preparation form. In this case the only possible method to achieve retention is the adhesive luting ^(9-11).

Even though such preparations completely lack a retentive form, long-term success of the restorations is well-documented when using a durable resin cement (e.g. PANAVIA™ 21, Kuraray Noritake Dental Inc., Japan) and proper bonding procedure ^{(10, 11)}.

For full-coverage restorations (e.g. crowns and FDPs), the guidelines for tooth preparation discussed before (minimum height of 4 mm and maximum convergence of 15 degrees) need to be applied in order to achieve the retention and resistance form required to make cementation with a conventional luting agent acceptable.

However, in reality this retention form is hard to realize due to several factors.

In cases of severe loss of tooth substance, achieving a minimum height of the abutment tooth is only possible with building up the tooth using a core build-up material which in some cases can be considered time consuming especially when the required build-up is minor (for example 1-2 mm). Moreover, increasing the height through core build-up is sometimes not possible, as in cases with short clinical crowns and insufficient occlusal clearance that is essential to provide the minimum thickness required for the restorative material. In such cases surgical crown lengthening is necessary to increase the height of the tooth without compromising the occlusal space required, which can be time consuming for the clinician and undesirable for the patient as it involves a surgical procedure and extends the treatment process.

Concerning the convergence angle, several studies showed that in reality and in daily practice of the dentist, the preparation angle is much higher than 15 degrees ^{(5, 6, 12, 13)}. For instance, preparations from general practitioners were evaluated digitally and compared to clinical recommendations and it was found that the mean convergence angle was 26.7 degree with the distopalatal angle being 31.7 degree ⁽¹²⁾.

Based on the previous concerns, it can be concluded that achieving a proper retention form during daily practice is hard to realize and thus conventional cementation in such cases can present clinical problems especially on the long term. Therefore, adhesive luting can be recommended in these cases as an alternative to conventional cementation ^{(6, 14)}. For full-coverage restorations with preparation designs featuring at least some mechanical retention, the use of self-adhesive resin cements can be considerate a good alternative as it provides high clinical success rates ^{(9, 15)}.

Conclusion / Clinical Significance:

• For non-retentive minimal-invasive restorations, traditional full-adhesive luting is a must.
• For full-coverage restorations, full-adhesive or self-adhesive luting is recommended.
• In case a retentive preparation with minimum height of 4mm and convergence angle of 6-12 degrees, adhesive luting as well as conventional cementation can be used.

2) MECHANICAL AND OPTICAL PROPERTIES OF THE RESTORATIVE MATERIAL

Flexural strength and translucency of the restorative material are critical factors that influence the decision which luting agent to use.

a) Flexural strength

As a general guideline for all-ceramic restorations, ceramics with low and medium flexural strength under 350 MPa should be adhesively luted with composite resin cements, as these restorations rely on resin bonding for reinforcement and support ^{(9, 14, 16)}. This includes feldspathic-, glass-, hybrid-ceramics and composite.

Although discussions on conventional cementation versus adhesive luting for high-strength ceramics with flexure strength of more than 350 MPa have been going on for a long time ⁽⁹⁾, there are several studies showing an increased stability and strength of all types of ceramics, even lithium disilicate and zirconia, when they are adhesively luted ^{(9, 17-20)}.

It is also important to consider that the documented success of most conventional cements is mainly combined with restorations made of metal or early generations of zirconia. Nonetheless, the clinical success of new generations of high-translucent zirconia can be significantly influenced by the luting agent as these new generations have notably lower flexural strength ⁽⁹⁾. And therefore, attention has to be paid to minimal material thickness together with adhesive luting to ensure long-term clinical success and prevent fractures ⁽⁹⁾.

Conclusion / Clinical Significance:

• For glass-ceramic, hybrid-ceramics and composites, adhesive luting is a must.
• For lithium disilicate and zirconia restorations, adhesive luting is highly recommended.
• For metal restorations, adhesive luting as well as conventional cementation can be used.

b) Translucency

To meet the increasing esthetic demands of the patients, new materials and techniques are continuously introduced, aiming to provide the perfect esthetic restorations. This includes not only new restorative materials but also new modifications to the luting agents as well. Highly translucent ceramics can deliver superior esthetics and therefore their popularity and clinical applications expanded widely among clinicians. It is nevertheless very important for the clinician to apprehend that the final esthetic result is influenced by the complete restorative complex and not just by the restorative material, as the luting agent is a key factor in achieving the desired high esthetics ^(21-24).

For that reason, the choice of an opaque conventional cement for cementation of high-translucent restoration should not be recommended as it can negatively influence the final esthetic results. Therefore, composite resin cements are the material of choice, as they are available in different shades and translucencies for the clinician to be able to choose the suitable resin cement to achieve the desired esthetics based on the restorative material and thickness as well as the color of the underlying abutment. Some composite resin cements offer try-in paste so that the clinician and the patient can visualize the final results before luting and therefore better choose the appropriate shade of the resin cement.

Conclusion / Clinical Significance:

• For all translucent ceramic restorations, adhesive luting is highly recommended.
• For metal and opaque high-strength zirconia restorations, adhesive luting as well as conventional cementation can be used.

3) SIMPLICITY OF THE WORKFLOW AND SPECIAL REQUIREMENTS OF THE WORKING ENVIRONMENT

The process of adhesive luting with full-adhesive composite resin cements (e.g. PANAVIA™ V5, Kuraray Noritake Dental Inc.) requires separate etching and priming procedures usually using a self-etch adhesive system (e.g. PANAVIA™ V5 Tooth Primer, Kuraray Noritake Dental Inc.) as well as a primer for the restorative material such as a universal primer that can be used for different substrates including metal, ceramics and composites (e.g. CLEARFIL™ CERAMIC PRIMER PLUS, Kuraray Noritake Dental Inc.). These procedures are technique sensitive and intolerant to contaminations, therefore the luting process needs a dry oral environment avoiding any contamination, such as saliva or blood, preferably using rubber dam, as any contamination can compromise the bond strength. Therefore, inability to maintain dry field as in case of subgingival preparation margins is considered a contraindication for traditional full-adhesive luting. However, this method provides very durable bond strength, therefore it is the luting method of choice for minimal invasive non-retentive preparations, such as resin-bonded FDPs, labial and occlusal veneers and inlay-retained FDPs, in which the retention is mainly dependent on the adhesion ^(9-11).

Still, in everyday practice, clinicians seek efficiency and effectivity by using a simple but durable luting agent for the insertion of full-coverage restorations such as tooth-or implant-supported crowns and FDPs. Although the conventional cements are simple and fast in their use, they provide little or no adhesion at all and therefore they are not recommended in several cases ^{(6, 9, 14, 15, 19, 20)}. A simple but reliable method can be well accomplished by the use of self-adhesive resin cements (e.g. PANAVIA™ SA Cement Universal, Kuraray Noritake Dental Inc.) as they can be considered the best alternative for full-adhesive adhesive luting in less critical situations that do not rely entirely on adhesion ^{(9, 15)}. Furthermore, self-adhesive resin cements are not as technique sensitive and intolerant to contaminations as traditional full-adhesive resin cements.

Typically, a MDP phosphate monomer is integrated in the self-adhesive resin cement, which is required to chemically bond to different substrates, making it possible for the resin cement to chemically bond to non-precious metals and zirconia as well as tooth substance. However, regardless of the self-adhesive resin cement, the use of a separate silane coupling agent is still required when bonding to silica-based ceramics (e.g. leucite, lithium silicate and lithium disilicate), hybrid ceramics and composite restorations.

Recently, a unique self-adhesive resin cement (PANAVIA™ SA Cement Universal, Kuraray Noritake Dental Inc.) was introduced: through an innovative and distinctive production technology, a silane-coupling agent (long carbon chain silane (LCSi)) is integrated in the cement, and thus being the real universal adhesive system that completely eliminate the need for any other adhesive or primer when being used for all substrates including glass ceramics. So the luting process can be in this case truly shortened to one step.

Therefore, this unique cement combines several advantages of adhesive luting as well as the straightforward procedure of the conventional cementation without compromising the clinical success, regardless of the type of the restorative material.

As a conclusion, adhesive luting has more benefits over conventional cementation, regarding retention, esthetics, stabilization of the tooth and the restoration as well as preventing micro leakage ^{(6, 9, 14-17, 19, 20, 25, 26)} (Table 1). Moreover, there are no absolute contraindications for adhesive luting other than hypersensitivity to methacrylate monomers, as self-adhesive resin cements can be used in cases where full-adhesive resin cements are contraindicated, such as inability to avoid contamination (Table 2). As a result, adhesive luting can be generally used in every clinical situation, whereas conventional cementation is limited (Table 3).

Dentist(s):

Prof. Dr. Florian Beuer
Professor and Chair, Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charité – Universitätsmedizin Berlin, Germany.

Dr. Adham Elsayed
Clinical and Scientific manager, Kuraray Europe GmbH, Hattersheim, Germany.

References

1. Ladha K, Verma M. Conventional and contemporary luting cements: an overview. J Indian Prosthodont Soc. 2010;10(2):79-88.
2. Schwartz NL, Whitsett LD, Berry TG, Stewart JL. Unserviceable crowns and fixed partial dentures: life-span and causes for loss of serviceability. J Am Dent Assoc. 1970;81(6):1395-401.
3. Gilboe DB, Teteruck WR. Fundamentals of extracoronal tooth preparation. Part I. Retention and resistance form. J Prosthet Dent. 1974;32(6):651-6.
4. Muruppel AM, Thomas J, Saratchandran S, Nair D, Gladstone S, Rajeev MM. Assessment of Retention and Resistance Form of Tooth Preparations for All Ceramic Restorations using Digital Imaging Technique. J Contemp Dent Pract. 2018;19(2):143-9.
5. 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.
6. 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.
7. 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.
8. 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.
9. Blatz MB, Vonderheide M, Conejo J. The Effect of Resin Bonding on Long-Term Success of High-Strength Ceramics. J Dent Res. 2018;97(2):132-9.
10. Chaar MS, Kern M. Five-year clinical outcome of posterior zirconia ceramic inlay-retained FDPs with a modified design. J Dent. 2015;43(12):1411-5.
11. 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;65:51-5.
12. Guth JF, Wallbach J, Stimmelmayr M, Gernet W, Beuer F, Edelhoff D. Computer-aided evaluation of preparations for CAD/CAM-fabricated all-ceramic crowns. Clin Oral Investig. 2013;17(5):1389-95.
13. Nordlander J, Weir D, Stoffer W, Ochi S. The taper of clinical preparations for fixed prosthodontics. J Prosthet Dent. 1988;60(2):148-51.
14. Blatz MB. Long-term clinical success of all-ceramic posterior restorations. Quintessence Int. 2002;33(6):415-26.
15. Blatz MB, Phark JH, Ozer F, Mante FK, Saleh N, Bergler M, et al. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. Clin Oral Investig. 2010;14(2):187-92.
16. Kern M, Thompson VP, Beuer F, Edelhoff D, Frankenberger R, Kohal RJ, et al. All ceramics at a glance. 3rd English Edition ed: AG Keramik; 2017.
17. Attia A, Abdelaziz KM, Freitag S, Kern M. Fracture load of composite resin and feldspathic all-ceramic CAD/CAM crowns. J Prosthet Dent. 2006;95(2):117-23.
18. Borges GA, Caldas D, Taskonak B, Yan J, Sobrinho LC, de Oliveira WJ. Fracture loads of all-ceramic crowns under wet and dry fatigue conditions. J Prosthodont. 2009;18(8):649-55.
19. Campos F, Valandro LF, Feitosa SA, Kleverlaan CJ, Feilzer AJ, de Jager N, et al. Adhesive Cementation Promotes Higher Fatigue Resistance to Zirconia Crowns. Oper Dent. 2017;42(2):215-24.
20. Weigl P, Sander A, Wu Y, Felber R, Lauer HC, Rosentritt M. In-vitro performance and fracture strength of thin monolithic zirconia crowns. J Adv Prosthodont. 2018;10(2):79-84.
21. Calgaro PA, Furuse AY, Correr GM, Ornaghi BP, Gonzaga CC. Post-cementation colorimetric evaluation of the interaction between the thickness of ceramic veneers and the shade of resin cement. Am J Dent. 2014;27(4):191-4.
22. Chang J, Da Silva JD, Sakai M, Kristiansen J, Ishikawa-Nagai S. The optical effect of composite luting cement on all ceramic crowns. J Dent. 2009;37(12):937-43.
23. Turgut S, Bagis B. Effect of resin cement and ceramic thickness on final color of laminate veneers: an in vitro study. J Prosthet Dent. 2013;109(3):179-86.
24. Volpato CA, Monteiro S, Jr., de Andrada MC, Fredel MC, Petter CO. Optical influence of the type of illuminant, substrates and thickness of ceramic materials. Dent Mater. 2009;25(1):87-93.
25. Al-Makramani BMA, Razak AAA, Abu-Hassan MI. Evaluation of load at fracture of Procera AllCeram copings using different luting cements. J Prosthodont. 2008;17(2):120-4.
26. Gu XH, Kern M. Marginal discrepancies and leakage of all-ceramic crowns: influence of luting agents and aging conditions. Int J Prosthodont. 2003;16(2):109-16.

As a company, Kuraray Noritake Dental is committed not just to creating innovative products, but also to building upon our successes. A perfect example of this approach is CLEARFIL Universal Bond Quick, our newest universal dental bonding agent. A descendant of the original CLEARFIL BOND SYSTEM F and CLEARFIL SE BOND, this one-step adhesive eliminates the need for waiting, rubbing or applying additional layers. With the introduction of a flip-top cap, CLEARFIL Universal Bond Quick is now more compact and efficient than ever.

Easier than ever to use

Thanks to the new flip-top cap, the bottle can easily be opened, manipulated and closed with just one hand. In addition, its unique nozzle allows for controlled dispensing of the adhesive and ensures that there is minimal wastage. Together, these improvements are intended to enable ideal results for both the dentist and the patient.

Rapid bond technology

Though its container may be different, the patented monomer technology of Kuraray Noritake Dental still forms the backbone of this product. Other adhesives tend to rely on “slow monomers” with relatively slow dentinal penetration, but CLEARFIL Universal Bond Quick combines Kuraray’s famous MDP monomer—scientifically proven to deliver stronger and more stable bonds than other manufacturers’ MDP—with hydrophilic amide monomers. This allows it to penetrate the dentine faster and more efficiently and provide a stable, moisture-resistant sealing of the cavity.

Combine with PANAVIA SA Cement Universal and CLEARFIL DC CORE PLUS

This universal adhesive pairs excellently with CLEARFIL DC CORE PLUS, a dual-cure, radiopaque core build-up material, to deliver durable, long-lasting restorations that dentists can trust. Delivered in a convenient automix system, CLEARFIL DC CORE PLUS possesses excellent compressive and flexural strength, with a filler loading weight of 74wt%.

CLEARFIL Universal Bond Quick is also suited for use with PANAVIA SA Cement Universal, a resin cement that similarly utilises MDP monomer technology for durable bonding. PANAVIA SA Cement Universal possesses a stable three-year shelf life at room temperature, effectively eliminating the need for refrigeration, and its improved endo tip allows for greater precision and control over cement placement during post cementation.

By combining excellence in performance with simplicity in use, Kuraray Noritake Dental’s CLEARFIL Universal Bond Quick represents an evolution in dental bonding agents. 

As a dental technician with many years of experience, Björn Roland has always pursued one goal in his lab: restorations that seamlessly mimic natural dentition and possess reliable functionality. Here, he discusses how he integrates Kuraray Noritake Dental’s dental solutions into his daily workflow and shares some tips for creating aesthetically-pleasing dental restorations.

Could you speak a little bit about your dental journey and how you were first introduced to Kuraray Noritake Dental’s range of products?

ROLAND: Well, I was first introduced to these products when I was in Japan about 15 years ago. I was there to undertake a course at the Osaka Ceramic Training Center of Shigeo Kataoka, but I had the possibility during this time to visit courses conducted by Hitoshi Aoshima. Aoshima is the person primarily responsible for Noritake Porcelain and who had the idea for the colouring, and he was also responsible for the idea of internal staining. I also had the possibility to complete a course with Aoshima and visit his dental lab in Tokyo, which enabled me to begin working with Noritake porcelain when I arrived back in Germany.

You spoke at IDS 2019 about the evolution of the KATANA™ Zirconia range, starting with the 2013 introduction of KATANA™ Zirconia ML. When did you first start working with this product?

When Kuraray Noritake Dental was formed in 2012, I was lucky enough to be one the first dental technicians to experience the multilayered technology that forms the backbone of KATANA™ Zirconia, to test it out before it was released to the German market. Prior to this, there was only a monocoloured zirconia material available, which you could stain yourself by dipping it into a staining solution, but I was never a big fan of it. From the moment that Kuraray Noritake came up with its multilayered approach, I could see the potential of KATANA™ Zirconia -simply put, it was easy to use and had a nice and aesthetic colour shift when used for restorations.

As a dental technician, do you use KATANA™ Zirconia in your everyday workflow?

In our laboratory we only use KATANA™. Of course, not everything is made from the multilayered variety—we have primarily used the monocoloured KATANA™ HT for the framework in the past, though we do use the multilayered option for monolithic restorations and for certain frameworks.

Do you use KATANA™ Zirconia in combination with CERABIEN™ ZR porcelain?

Yes, always. For me, it is a perfect combination. Not only are they easy to use together, but they also combine to create aesthetic restorations with great, natural colour and a high level of flexural strength. In our laboratory, everyone uses CERABIEN™ ZR porcelain, from those who are just starting with ceramics through to the experienced and highly skilled dental technicians. Even technicians who have come from other dental laboratories and tried other porcelain materials have adapted very quickly to using it and seem to really like it. The chipping risk with CERABIEN™ ZR porcelain is very low, and we truly admire the brilliance of the colour.

Is CERABIEN™ ZR porcelain a material, in your opinion, that can benefit those with expert knowledge of porcelains?

Of course. For those who are experienced in dealing with ceramic materials and understand how they behave, they can absolutely achieve high-end results with CERABIEN™ ZR. It’s important to remember, though, that even dental technicians who aren’t so familiar with ceramic veneering are also getting good results out of it - it’s not too difficult to use and get good results.

Do you use any other Kuraray Noritake Dental products in your dental lab?

Apart from KATANA™ and CERABIEN™ ZR, one product that I personally like and use from Kuraray Noritake Dental is Meister Cones, which are these small paper cones that assist with the finishing and polishing of porcelain surfaces. I brought them back with me to Germany from Japan and find them to be very handy in the laboratory. 

Though one is a master dental technician and the other a dentist, Daniele Rondoni and Dr Nicola Scotti share a passion for discovering new materials and technologies to better provide aesthetic, durable restorations for patients. Here, they discuss their dental journeys and how they have integrated Kuraray Noritake Dental’s KATANA™ Zirconia range into their workflows.

How did you get started in dentistry, and what was it about dentistry that first interested you?
Dr Nicola Scotti: Well, my professional interest goes back 15 or 20 years at this point, but I was first introduced to dentistry as a child through my father, who was a dentist himself. I grew up looking at teeth, looking at models, and it was something that was just in my blood. When I had to decide what to study, I followed my heart and decided to become a dentist, and ever since I have remained dedicated to learning new things about it.

Daniele Rondoni: I have a similar story to Nicola. My uncle was a dental technician and that influenced my decision to become a dental technician and open up my own dental laboratory. Though there were many things that interested me, I have always focused on the major possibility that this profession offers, the opportunity not only to use your hands but also to combine this skill with the newest dental technologies available.

Regarding this combination of manual and digital skills, do you still see a role for the dental professional as a craftsperson in this increasingly digital industry?
Scotti: Dentistry, even if the digital influence continues to grow, will surely continue to be a profession defined by what we can do with our hands. You cannot complete a restoration, for example, without having these manual skills. There is also the matter of personalisation. Though machines can create flawless dental restorations in great numbers, it is the artistry of the dental technician that allows our patients to have customised solutions made with the materials and the shapes that suit them best. If you want to provide natural-looking restorations for your patients, digital dentistry is a great tool to use, but you need to have manual skills and a passion for the work as well.

Rondoni: As a dental technician, it is important to remember that my work depends on technology, and so in this way, digital dentistry and the new-generation dental materials have helped my work greatly. Using this technology for individual situations is an essential part of my role, and excellent materials like Kuraray Noritake Dental’s KATANA™ Zirconia range make my artistic vision regarding these situations more easily achievable.

Scotti: In my opinion, even if 90 per cent of the workflow is digital in nature, you need that artistic input and vision for the remaining 10 per cent in order to really create a successful restoration. With KATANA™ Zirconia, these two aspects come together and allow you to create something really amazing.

Speaking of the KATANA™ Zirconia range from Kuraray Noritake Dental, is this material a part of your everyday workflow at this point? What do you see as its benefits?
Rondoni: It is definitely a part of my everyday workflow. I have worked with Noritake materials for many years, but when Kuraray released its newest generation of zirconia, it totally changed my approach in the dental laboratory. Over the last five years, KATANA™ Zirconia has greatly influenced my workflow; it allows me to use certain technologies without forgoing artistic needs, and since it’s available in different translucencies and shades and so on, I can create aesthetic restorations for individual cases with ease.

Scotti: In the past, I didn’t regard zirconia as a material for dentists. We used to take the impression and then ask the dental technician to use zirconia to make a restoration, but we didn’t use the material ourselves. What the KATANA™ Zirconia Block for chairside has introduced is a totally new concept of how zirconia can be used by dentists themselves. Having a material that can create monolithic full-contour restorations, even single crowns, is incredible. Its aesthetic qualities are fantastic as well, as Daniele mentioned, and it gives us a truly new option for treating patients.

Earlier this year, Kuraray Noritake Dental invited dental professionals from all over Europe to a symposium in Berlin that highlighted the newest research and clinical findings with the KATANA™ Zirconia Block, the latest addition to the KATANA™ family. Among those to present was Dr Nicola Scotti, an assistant professor at the Department of Cariology and Operative Dentistry at the University of Turin’s Dental School and operator of his own private practice.

Dr Scotti began working with Kuraray Noritake Dental’s range of products in 2012, having been asked to test the CLEARFIL MAJESTY™ ES-2 composite resin before its launch, and soon afterwards began what he terms a “close collaboration” with the company. “I consider Kuraray Noritake Dental to be a very serious company, one built on strong scientific foundations and with a great interest in innovation and consulting with opinion leaders,” he added.

When Dr Scotti was presented with the opportunity to use the KATANA™ Zirconia Block in April 2018, it required a significant learning curve as he had never used zirconia for restorations before. “I am not a dental technician, and when I received the Block for the first time, I realised that I would have to add some skills to be able to work the material in the best possible way,” he said. With the assistance of master dental technician Daniele Rondoni—facilitated by Kuraray Noritake Dental—Dr Scotti was able to learn how to process and characterise zirconia, as well as understand the optical behaviour of KATANA™. “I must say that the material, overall, is easy to use and provides amazing aesthetic results,” he added.

As part of his presentation, Dr Scotti showed several case studies that had been conducted with KATANA™ Zirconia Block. One of these focused on a 24-year-old male patient referred to him with a discoloured upper incisor resulting from blunt trauma. “The patient had a fairly immediate aesthetic need, but in this case I was unable to perform external whitening to lessen the discolouration,” explained Dr Scotti. “However, I was able to solve the case by creating an adhesive crown made from a KATANA™ Zirconia Block. Though the cervical area still showed a slight colour difference to the neighbouring teeth, it was not visible in the patient’s smile and he was extremely happy with the result,” Dr Scotti continued.

Overall, Kuraray Noritake Dental’s KATANA™ Zirconia Block is a great step forward for zirconia restorations, according to Dr Scotti. “Ten years ago, no one would have imagined being able to make a central incisor restoration out of zirconia,” he said. “Thanks to the multi-layered technology behind the natural aesthetics of this block, today this is no longer a dream.”

Manufactured from Kuraray Noritake Dental’s proprietary zirconia powder, new KATANA™ Zirconia Block delivers aesthetic, natural-looking restorations. However, it is not only aesthetic value that this all-ceramic solution provides. Its superior mechanical properties were designed for reliable, repeatable fabrication of full-contour prostheses.

Impressive flexural strength

The multi-layered KATANA™ Zirconia Block possesses a flexural strength of 763 MPa, which is far higher than that of lithium silicate (LS) glass-based ceramics. This means that restorations made with the KATANA™ Zirconia Block can be designed to have thinner walls than those made with LS glass. This has now resulted in great mechanical properties and beautiful aesthetics that are now possible for all single-unit anterior and posterior restorations.

Fast chairside processing

Thanks to its integration with Dentsply Sirona’s CEREC® CAD/CAM system and SpeedFire™ ovens, the KATANA™ Zirconia Block is perfect for chairside processing and the fabrication of prostheses. Dentists only require 15 minutes for dry milling a crown with the CEREC milling unit and an additional 18 minutes is required for the sintering of the block.

A highly precise material

Dr Hendrik Zellerhoff runs a dental practice in Laer, located in the North Rhine-Westphalia district of Germany. As a digital dentistry and CEREC specialist, he has used the KATANA™ Zirconia Block for more than 40 cases in his practice since March 2018 and praises its perfect balance of aesthetics and mechanical performance. “Its strength is a major advantage—the bend strength totals 763 MPa,” says Dr Zellerhoff. “This means that it can even be used to create extremely thin walls, which in turn means minimally-invasive work. In addition, the margins are even more slender than on glass ceramics.” 

“Due to the fact that zirconia shrinks to the final size during the sintering process, an approximately 25 per cent oversized restoration needs to be milled out,” continues Dr Zellerhoff.

“This is executed using very fine milling cutters. Therefore, a larger workpiece is processed using smaller instruments. This leads to high-precision margins and occlusal surfaces. Only after this does dense sintering take place. The exact shrinkage factor is stored in the barcode on the block. Almost no rework is required in the occlusal or approximal areas. We even do without a try-in after sintering—we glaze immediately. This fact alone is really fascinating, even for long-standing, ‘pampered’ CEREC users.”

TEETHMATE DESENSITIZER: A natural solution for sensitive teeth

Kuraray Noritake Dental’s TEETHMATE DESENSITIZER is designed to provide an immediate and long-lasting solution for dentine sensitivity. Owing to a specially modified powder free of potential irritants like methacrylates and colophony resins, TEETHMATE DESENSITIZER is biocompatible and harmless to tissue. The first desensitiser to form hydroxyapatite, TEETHMATE DESENSITIZER possesses a neutral taste that will please patients. Since its introduction in 2013, dentists have hailed the product for its safe tubule sealing and for providing patients with immediate relief.

TEETHMATE DESENSITIZER consists of a powder, composed mainly of calcium phosphate, and a liquid, whose chief component is water. The powder and liquid simply need to be mixed. After the paste has been applied with a superfine brush to the affected area for 30 seconds, the material sets into hydroxyapatite, providing an instant reduction of hypersensitivity by sealing the dentinal tubules and microcracks in the enamel.

Hydroxyapatite: The human body’s strongest mineral

The presence of hydroxyapatite encourages tooth remineralisation, protecting teeth against hypersensitivity and after professional tooth cleaning. TEETHMATE DESENSITIZER is composed of two different calcium phosphates that react under water to form hydroxyapatite. Since Kuraray Noritake Dental’s technology ensures the right calcium–phosphate ion ratio with a suitable pH level, the newly formed hydroxyapatite acts as if it were the patient’s own, crystallising so that it can neatly seal dentinal tubules and enamel cracks.

Suitable for most sensitivity issues

TEETHMATE DESENSITIZER has a wide range of indications, from whitening-related dentine sensitivity to the treatment of dentine exposed by periodontitis, abraded by harsh toothbrushing, or prepared for fillings and/or restorations.

TEETHMATE DESENSITIZER is an invisible and durable form of treatment. When applied, it occludes open dentinal tubules without leaving a film on the tooth. It is fast and easy to use—simply mix the powder and liquid, apply with a rubbing motion to the sensitive region for 30 seconds and rinse lightly with water. No air blowing or light curing is required, as the calcium phosphates in the substance harden on their own, providing patients with fast relief from sensitivity-related pain.

Proven effectiveness

In a survey conducted by Kuraray Noritake Dental, Japanese dentists were asked to rate the effectiveness of TEETHMATE DESENSITIZER. Of the 285 respondents, 92 per cent said that they were satisfied with the product’s effectiveness.

No impact on bond strength

TEETHMATE DESENSITIZER has been clinically proven not to reduce the bond strength of adhesives or cements when it is used prior to their application. This is a considerable advantage for dentists using etch and rinse adhesives, for instance, as they can apply TEETHMATE DESENSITIZER without any concerns about potentially deleterious effects on restorations. A smart, invisible and durable form of dentine sensitivity treatment, TEETHMATE DESENSITIZER promises to satisfy both dentists and patients.

In 1978, Kuraray shook up the dental market with the introduction of CLEARFIL BOND SYSTEM F, the world’s first total-etch adhesive system. Having inaugurated the era of adhesive dentistry, we steadily introduced new dental products over the following years. In 1983, Kuraray introduced the PANAVIA EX resin cement. By utilising our patented MDP monomer technology developed in-house, PANAVIA EX enabled Kuraray to set the industry standard for adhesion—a position we have held in the decades since. This year marks the 40th anniversary of Kuraray’s entry into the commercial dental products market, providing a perfect opportunity to reflect on how far we have come since.

Kuraray—Rooted from a true trailblazer 
Founded in June 1926 by Magosaburo Ohara in Kurashiki in Japan, Kuraray has transcended our humble origins as a producer of rayon to become a leading global manufacturer of medical products, materials, textiles, chemicals, resins and much more. Our commitment to research and development in the fields of chemistry and engineering has led to many market firsts and a reputation as a pioneer of new products and technologies. 

A history of innovation
From the very beginning, Kuraray has been focused on the manufacture of high value-added products. At the time of the business’s birth, rayon was a new type of synthetic material, and over the ensuing years, Kuraray was able to master its production. In 1950, we became the first company in the world to develop the technology to mass-produce POVAL (polyvinyl alcohol), paving the way for the production of the new synthetic fibre Vinylon in the same year. CLARINO, a water-resistant synthetic leather substitute for shoes, bags and other items, was released in 1964 after extensive research and testing, and quickly collected international awards for its technology.

Kuraray’s continued emphasis on independently developed proprietary technologies and techniques, rather than relying on imported alternatives, has enabled our company to provide original, high-quality products for a variety of different industries. High on this list is dentistry.

The Kuraray Noritake Dental era
In April 2012, Kuraray Medical and Noritake Dental Supply merged to form Kuraray Noritake Dental. By bringing together the materials and technologies developed by each of these market-leading companies, Kuraray Noritake Dental has continued to deliver dental bonding agents, ceramics and other reliable products to over 90 countries worldwide. The KATANA Zirconia range, for example, employs our unique multi-layered zirconia technology to provide a ceramic restorative material with superior translucency and perfect blending properties, while rapid bond technology ensures that CLEARFIL Universal Bond Quick delivers a lasting bond faster and easier than ever. 

Through a focus on research and production, Kuraray Noritake Dental is ideally positioned to continue providing leading-edge solutions to dental issues both now and in the future.