429 Too Many Requests

Case report by Dr. Wissam Dirawi, DDS

During the last decade, zirconia has increasingly established itself as the material of choice in oral prosthodontic rehabilitation. Its great mechanical and inert properties are the main reason for this trend. Since the introduction of multi-layered zirconia blanks more than ten years ago, the optical properties have been improved dramatically. The multi-layered zirconia used nowadays (e.g. KATANA™ Zirconia YML from Kuraray Noritake Dental Inc.) offers well-balanced mechanical properties, translucency and colour. It allows dental technicians from all over the world to produce aesthetic full-contour restorations that are merely stained.

Even in the anterior region, stained monolithic restorations may be an option. Factors such as the age of the patient, the internal colour structure of the adjacent dentition, the number of teeth to be restored (one versus all four or six maxillary anterior teeth), the aesthetic demands of the patient and financial aspects should be taken into account in the material selection process. In the case described below, full-contour zirconia was selected for several reasons.

BACKGROUND

The 71-year-old female presented in the clinical due to aesthetic problems in the maxillary anterior region. Oral hygiene was good and the patient was a non-smoker. Infraposition of the existing implant-based crown (Nobel Biocare Brånemark RP fixture) in the position of the right central incisor (tooth #11 according to the FDI notation) was evident. Moreover, gingival retraction was observed on the maxillary right lateral incisor (tooth #12), while the left lateral incisor (tooth #22) has a major composite filling with discolouration. The patient expressed the desire to adjust the gingival level differences and to restore the four maxillary incisors with all-ceramic crowns for optimal aesthetics.

Fig. 1. Initial situation: Frontal view.

Fig. 2. Initial situation: Facial view.

Fig. 3. Initial situation: Occlusal view of the maxilla.

Fig. 4. Initial situation: Occlusal view of the mandible.

MATERIAL SELECTION

Due to the decision to restore all four anterior incisors, monolithic zirconia was a suitable material option. It would allow the team to obtain the desired results within the financial framework. In order to meet the aesthetic demands of the patient, provide for the required mechanical properties and allow for proper masking of the underlying structures, KATANA™ Zirconia YML was selected. It offers colour, translucency and flexural strength gradation throughout the multi-layered blank.

TREATMENT PROCEDURE: FROM PREP TO TEMPORIZATION

In order to design the indirect restorations, a digital impression was taken with an intraoral scanner and the data was transferred to the dental laboratory Teknodont in Malmoe, Sweden. There, a digital wax-up was created. After patient approval, a matrix was produced and sent to the clinic. Here, the old restorations were removed and the three maxillary incisors (all but the one replaced by an implant) prepared for full coverage restorations. A healing abutment was placed on the implant and a temporary bridge produced chairside using the matrix and Protemp 4 Temporization Material (3M) in the shade A3. Subsequently, a gingivectomy was carried out with a ceramic burr (Ceratip, Kt.314.016 – KOMET) in the buccal aspect of the left central and lateral incisor.

Fig. 5. Chairside-produced temporary in the patient’s mouth.

After the patient’s approval of the aesthetics, phonetics and function of the temporary restoration, the situation was captured with an intraoral scanner again. This allowed the team to duplicate the shape of the construction. Based on the acquired data, a new set of splinted temporary crowns made of PMMA (HUGE Multilayer PMMA) in the shade A3 was milled in laboratory. They were placed to allow the patient to further evaluate the aesthetic appearance and function for a couple of weeks. The patient was happy with the phonetics, function and appearance of the crowns, which were merely slightly too bright in comparison to the adjacent teeth, and approved the shape for the production of the permanent restorations.

Fig. 6. Printed model …

Fig. 7. … with splinted PMMA crowns.

Fig. 8. Lab-made temporary restorations.

Fig. 9. Long-term temporary in place: Lateral view from the right.

Fig. 10. Long-term temporary in place: Frontal view.

Fig. 11. Long-term temporary in place: Lateral view from the left.

FINAL RESTORATIONS: PRODUCTION AND CEMENTATION

Based on the dataset of the temporary restorations, four separate crowns – one implant and three tooth-based – were designed in full contour. Without any anatomical reduction, the restorations were milled from KATANA™ Zirconia YML. Based on the evaluation of the temporary restoration, the shade selected this time was A3.5. CERABIEN™ ZR FC Paste Stain was used for external staining and glazing of the surface. Still in the laboratory, the implant-based crown was cemented to the gold-shaded titanium abutment (Elos Medtech) with PANAVIA™ V5 (Kuraray Noritake Dental Inc.) in the shade opaque for an improved masking effect.

While the abutment crown was screwed onto the implant and the screw hole closed with composite, the three tooth-based crowns were placed using PANAVIA™ SA Cement Universal (Kuraray Noritake Dental Inc.).

Fig. 12. Final restorations on the model.

Fig. 13. Intraoral situation prior to restoration placement.

CONCLUSION

Multilayered zirconia is a suitable material for many clinical situations. Due to the availability of modern types of highly translucent, multi-layered blanks, it is possible to produce aesthetic outcomes even when using the material monolithically – not only in the posterior region, but also in the aesthetic zone in some indications. The present case shows that very good results and patient satisfaction can be obtained. And due to outstanding mechanical properties, these outcomes may be expected to last for a long time.

Fig. 14. Immediate treatment outcome: Facial view.

Fig. 15. Immediate treatment outcome: Frontal view.

Fig. 16. Immediate treatment outcome: Occlusal view.

Dentist:

WISSAM DIRAWI

Dr. Wissam Dirawi, Malmoe, Sweden. DDS.
Specialist in Oral Prosthodontics and Senior Adviser at Aqua Dental.

2000 Master´s degree in dentistry.
2000 - 2018 General Dentist in public dental care and private practice.
2011 - 2018 Part-time teacher and researcher at Malmö University, Faculty of Dentistry.
2018 Specialist in Oral Prosthodontics. Senior clinical adviser. Lecturer.

References

- Alfadhli R, Alshammari Y, Baig MR, Omar R. Clinical outcomes of single crown and 3-unit bi-layered zirconia-based fixed dental prostheses: An up to 6- year retrospective clinical study: Clinical outcomes of zirconia FDPs. J Dent. 2022 Dec;127:104321.
- Le M, Papia E, Larsson C. The clinical success of tooth- and implant-supported zirconia-based fixed dental prostheses. A systematic review. J Oral Rehabil. 2015 Jun;42(6):467-80.
- Alammar A, Blatz MB. The resin bond to high-translucent zirconia-A systematic review. J Esthet Restor Dent. 2022 Jan;34(1):117-135.
- Sadowsky SJ. Has zirconia made a material difference in implant prosthodontics? A review. Dent Mat 2020; 36: 1–8.
- Mazza LC, Lemos CAA, Pesqueira AA, Pellizzer EP. Survival and complications of monolithic ceramic for tooth-supported fixed dental prostheses: A systematic review and meta-analysis. J Prosthet Dent 2022; 128: 566–74.
- Passia N, Mitsias M, Lehmann F, Kern M. Bond strength of a new generation of universal bonding systems to zirconia ceramic. J Mech Behav Biomed Mater. 2016; 62:268–274.
- Sailer I, Makarov NA, Thoma DS, Zwahlen M, Pjetursson BE. All-ceramic or metal-ceramic tooth- supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs). Dent Mater 2015; 31:603-623.
- Pjetursson BE, Sailer I, Makarov NA, Zwahlen M, Thoma DS. All-ceramic or metal-ceramic tooth- supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part II: Multiple-unit FDPs. Dent Mater 2015; 31:624–639.

Case by Dr. Ioannis Memis

Single-shade or two-shade approach? Using modern resin composites, it is possible to treat virtually every patient in need of a direct restoration in an aesthetic way using one of those two techniques. If the defect is rather small, a single shade of composite restorative in a body opacity may be sufficient – especially when the tooth to be restored is in the posterior region. Larger defects and those located in the aesthetic zone may require a combination of two different shades – one as a dentin replacement and one as translucent as enamel – to closely imitate the optical characteristics of the natural tooth.

With CLEARFIL MAJESTY™ ES-2, Kuraray Noritake Dental Inc. offers a complete composite system designed to simplify procedures in bot, the single-shade and the two-shade approach. CLEARFIL MAJESTY™ ES-2 Classic is a typical composite for the single-shade technique consisting of 18 shades offered in a single universal opacity. Shade determination is brightness-based, meaning that the brightness is selected first and the hue and colour saturation in a second step (using the VITA Classical A1 – D4 shade guide). For those who want to skip shade determination completely, CLEARFIL MAJESTY™ ES-2 Universal has been introduced. It consists of only two shades for the anterior and one shade for the posterior region, selectable without using shade tabs. For the two-shade technique, CLEARFIL MAJESTY™ ES-2 Premium is the solution: It allows users to copy natural enamel and dentin layers with a total of seven enamel, seven dentin and four translucent shades. Its exceptional feature: pre-defined colour combinations with one Premium shade combination covering three VITA Classical shades. A natural blending into the environment is achieved with the Light Diffusion Technology in the formulation.

All three versions of CLEARFIL MAJESTY™ ES-2 are compatible with each other and offer the same favourable handling properties. The use of different techniques, shades and opacities is demonstrated using the following patient case.

YOUNG PATIENT WITH MULTIPLE CARIOUS LESIONS

A 24-year-old female patient was referred from undergraduate clinic of Operative Dentistry of the Aristotle’s University of Thessaloniki - School of Dentistry (Greece). Patient presented multiple interproximal carious lesions in need of restorative treatment. In the clinical and radiographic examination, the following defects were identified:

Quadrant 1 (maxillary right):

- Distal lesion on the lateral incisor (Class III)

- Mesial and distal lesions on the first premolar (Class II)

- Mesial and distal lesions on the second premolar (Class II)

- Mesial lesion on the first molar (Class II)

Quadrant 2 (maxillary left):

- Distal lesion on the lateral incisor (Class III)

- Mesial lesion on the first premolar (Class II)

- Mesial and distal lesions on the second premolar (both Class II)

- Mesial lesion on the first molar (Class II)

Quadrant 3 (mandibular left):

- Distal lesion on the first molar (Class II)

- Mesial lesion on the second molar (Class II)

In a stepwise procedure, the teeth were restored with CLEARFIL MAJESTY™ ES-2 either in a single-shade or in a two-shade approach depending on the size of the lesions.

INITIAL SITUATION

Fig. 1. Initial situation: Frontal view.

Fig. 2. Occlusal view of the maxilla.

Fig. 3. Occlusal view of the mandible.

RESTORING THE TEETH IN QUADRANT 1

The six carious lesions in this quadrant were restored in three steps. At first, the focus was on the first molar and second premolar. Opening the larger cavity mesially of the first molar provided access to the smaller lesion on the premolar’s distal surface. After caries excavation and cavity preparation, rubber dam was placed and fixed with a clamp on the second molar. The enamel in the cavities was treated with phosphoric acid etchant for 15 seconds before CLEARFIL™ Universal Bond Quick (Kuraray Noritake Dental Inc.) was applied according to the manufacturer’s instructions. For a morphologically correct designing of the proximal contact point and area, the use of a sectional matrix system with rings was utilized. Both cavities were restored with CLEARFIL MAJESTY™ ES-2 Premium in the shades A3D and A2E. Finishing and polishing of the occlusal surface accomplished with silicon cups and Twist Dia disks on a slow speed handpiece.

In the second step, the distal lesion on the first and mesial lesion on the second premolar were restored in an identical procedure with CLEARFIL MAJESTY™ ES-2 Premium in the shade A3D and CLEARFIL MAJESTY™ ES-2 Classic in the shade A3. A different approach was selected in step 3 for the lesions on the distal part of the lateral incisor and the mesial part of the first premolar. Due to the small size and the all-but-prominent position of the lesions, a single-shade technique using CLEARFIL MAJESTY™ ES-2 Classic in the shade A3 was selected. Between the lateral incisor and canine, a posterior sectional matrix was placed in an upright position and fixed with a wedge to support a proper restoration of the contact point, while both elements were used in the usual way between the canine and first premolar.

Fig. 4. Simultaneous restoration of the mesial lesion on the first molar and the distal lesion on the second premolar with CLEARFIL MAJESTY™ ES-2 Premium.

Fig. 5. Restoration of the distal lesion on the lateral incisor and the mesial lesion on the first premolar with CLEARFIL MAJESTY™ ES-2 Classic.

RESTORING THE TEETH IN QUADRANT 2

For the small disto-palatal lesion on the maxillary left lateral incisor, a single-shade technique with CLEARFIL MAJESTY™ ES-2 Classic in the shade A3 also produced aesthetic outcomes. The four lesions at the posterior region of the quadrant were restored in two steps – one for each pair of proximal lesions – with a combination of CLEARFIL MAJESTY™ ES-2 Premium in the shade A3D and CLEARFIL MAJESTY™ ES-2 Classic in the shade A1.

Fig. 6. A single-shade technique is sufficient to aesthetically restore this small lesion on the left lateral incisor.

Fig. 7. Simultaneous restoration of the mesial lesion on the second premolar and the distal lesion on the first premolar.

Fig. 8. Simultaneous restoration of the mesial lesion on the first molar and distal lesion on the second premolar.

RESTORING THE TEETH IN QUADRANT 3

In this quadrant, only a single pair of proximal lesions needed treatment. A simultaneous restoration procedure was selected once again due to the favourable space conditions. Although the size of the lesion was like those in the posterior region of the maxilla, a single-shade restoration was selected with the use of CLEARFIL MAJESTY™ ES-2 Classic (shade A3).

Fig. 9. Treatment of the lesions in quadrant 3.

CONCLUSION

In the present patient case, several different shades, opacities, and combinations of CLEARFIL MAJESTY™ ES-2 were utilized either in a single- or in a two-shade approach. All combinations and techniques produced good outcomes. As shown in Figure 4, the enamel opacity of CLEARFIL MAJESTY™ ES-2 Premium is visibly more translucent than the universal opacity of CLEARFIL MAJESTY™ ES-2 Classic. Experience shows that enamel shades translucency is highly valuable for aesthetic anterior restorations, while in posterior restorations, the universal shade approach is aesthetically adequate, particularly for medium-sized restorations, as shown in Figure 9. This is clearly an evidence of Light Diffusion Technology which is blending hue and colour saturation to the surrounding tooth structure.

Handling of all selected composite pastes is comfortable: non-sticky, adaptable to cavity walls and allowing precise occlusal sculpting. Polishing with Silicone Cups and TWIST DIA for Composite is easy, quick and leaves a natural gloss on the surface.Dentist:

DR. IOANNIS MEMIS

Postgraduate Student, Operative Dentistry Dept., School of Dentistry
Aristotle University of Thessaloniki, Greece

Case by MDT Daniele Rondoni and MDT Roberto Rossi

Full-contour or an anatomically reduced design? When we need to decide how we want to design and finish a zirconia restoration we are asked to produced, many factors need to be taken into account – from aesthetics to function and from time- to budget-related ones. As the outcomes are strongly dependent on the optical and mechanical properties of the zirconia used, however, we are convinced that the first thing to do is to select a portfolio of high-quality zirconia materials. By experimenting with them in the dental laboratory, using different designs and finishing approaches with aligned materials and by comparing the results, you will be able to select the most appropriate concepts for your everyday work. In addition, you will develop a clear idea on when to use which concept.

Our own selection

The zirconia portfolio used in our dental laboratory consists of the KATANA™ Zirconia Multi-Layered Series from Kuraray Noritake Dental Inc. It consists of three materials with a multi-layered colour structure designed to meet different needs with regard to flexural strength and translucency (KATANA™ Zirconia UTML, STML and HTML PLUS) and one material with colour, translucency and flexural strength gradation (KATANA™ Zirconia YML). Due to the favourable optical properties of this series and new effect liquids, it is often possible to opt for a full-contour design or – in the anterior region – for a slight cutback limited to the vestibular area plus a micro-layer of porcelain.

The effect liquids – Esthetic Colorant for KATANA™ Zirconia – were introduced n early 2023. They are applied to the surface of the milled zirconia to pre-treat tissue areas of large restorations, to add specific individual characteristics to the restoration or to prevent a greyish effect caused by the shining through of discoloured abutment teeth or metal parts. While most liquids are used on the outer surface of the restorations, the latter effect is achieved by applying Esthetic Colorant OPAQUE or WHITE to the intaglio.

Case example

The following case example describes the use of Esthetic Colorant in the context of producing a full-contour screw-retained implant bridge made of zirconia with a titanium bar. The zirconia part was milled from KATANA™ Zirconia YML, the vestibular morphology refined with rotating instruments and then, the vestibular, palatal and occlusal surfaces were treated with Esthetic Colorant as shown in Figures 1 and 2. The true colour effect is revealed after sintering.

Fig. 1. Frontal view of the milled zirconia structure after the application of Esthetic Colorant in the shades BLUE, GRAY, ORANGE and PINK.

Fig. 2. Occlusal view of the milled zirconia structure after the application of Esthetic Colorant BLUE, GRAY, ORANGE and PINK.

Fig. 3. Nicely pre-treated zirconia structure after sintering.

By adding some CERABIEN™ ZR FC Paste Stain and Glaze in the vestibular area and to the tissue parts, it is possible to finish this restoration in a nice way. The contact areas are always just polished to a high gloss in our approach, as it is the most antagonist-friendly way of treating the surface. As a final measure, the zirconia structure was connected to the titanium bar before it was sent to the dental office for try-in.

Fig. 4. Frontal view of the finalized zirconia part.

Fig. 5. Occlusal view of the structure after finishing.

Fig. 6. Connecting the zirconia superstructure and titanium bar.

Conclusion

With a well-selected zirconia portfolio and aligned finishing solutions, it is easy to establish concepts that allow you to respond to the needs of virtually every patient in a streamlined way. In our experience, the use of high-quality products with good aesthetic properties – a high translucency and naturally pre-shaded multi-layer structure – pays off as it allows us to reduce the thickness or do without a porcelain layer. In this way, we are able to increase the efficiency of our procedures without compromising the outcomes.

The KATANA™ Zirconia Multi-Layered Series and the new Esthetic Colorant for KATANA™ Zirconia support us in an ideal way by allowing us to efficiently produce a perfect base for whatever finishing approach we select.

Dentists:

Case by Kanstantsin Vyshamirski

A male patient (47 years of age) presented to his dentist with severe damage to his teeth. His main request was to increase aesthetics, to achieve a more pleasing envisaged aesthetic area. A side request was to achieve a ‘whitening but natural look’. This was achieved by using a lighter colour palette of zirconia and porcelain materials.

The final result was achieved through the creation of a wax-up, followed by a mock-up, provisional restoration and finally adhesive bonding of the zirconia crowns.

INITIAL SITUATION

Fig. 1. Initial situation. Male patient (47 years of age).

Fig. 2. Planning the new smile according to patient’s aesthetic and functional parameters.

Fig. 3. Mock-up in place to check the new look in the patient’s mouth.

Fig. 4. KATANA™ Zirconia YML shade A1 crowns with labial cutback after milling.

Fig. 5. Crowns after sintering on the plaster model.

Fig. 6. Noritake CERABIEN™ ZR porcelain layering map.

Fig. 7. Finishing the labial surface using both polishing and selfglaze. On the palatal side of the crowns only CERABIEN™ FC Paste Stain stains and glaze were used for finishing. To aid in optimisation of the soft tissue condition the palato-cervical and near proximal areas were polished.

Fig. 8. Finished crowns on the plaster model.

Fig. 9. Try-in using PANAVIA™ V5 White try-in paste, to confirm the proper appearance. For the final adhesive cementation PANAVIA™ V5 White has been used.

FINAL SITUATION

Fig. 10. Situation after seven months. The result is aesthetically pleasing and the gingival condition excellent.

Fig. 11. Recall after 1.5 years.

Dentist:

KANSTANTSIN VYSHAMIRSKI

Kanstantsin started his dental technician career in 2014. His speciality is aesthetic prosthetic porcelain works. Kanstantsin is an experienced user of KATANA™ Zirconia and Noritake porcelains. He owns his lab in Riga, Latvia.

Clinical case by Dr. Florian Zwiener

The 85-year-old female patient presented after osteosynthesis of a multiple mandibular fracture she had sustained after a fall. During fixation, a massive nonocclusion had occurred in the left posterior region of the mandible (teeth 34 to 37; FDI notation). The patient desired to be able to chew properly again in this area. After endodontic treatment of the two avulsed central incisors, which had been replanted in the hospital, and periodontal therapy, a bite elevation was planned on the left side.

The idea was to restore the teeth and elevate the bite with three onlays and a crown made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent). During tooth preparation, however, a longitudinal root fracture was detected on the first molar. Therefore, only the first premolar was restored in this session. For this purpose, an onlay was produced chairside (with the CEREC system, Dentsply Sirona) and adhesively luted with PANAVIA™ V5 (Kuraray Noritake Dental Inc.). The first molar was extracted. One week later, the extraction socket, which was still healing, was modelled for the ovoid pontic using an electrotome loop. The second premolar and molar were prepared as abutment teeth for a bridge. The bridge was then milled from KATANA™ Zirconia Block for Bridge in the shade A3.5 and individualized with CERABIEN™ ZR FC Paste Stain (both Kuraray Noritake Dental inc.). After another week, the bridge was luted with the self-adhesive resin cement PANAVIA™ SA Cement Universal (Kuraray Noritake Dental Inc.) following sandblasting.

Fig. 1. Situation after multiple mandibular fracture on the left side.

Fig. 2. Clinical situation at the initial appointment in the dental practice.

Fig. 3. Open bite in the mandibular left posterior region.

Fig. 4. Bridge design …

Fig. 5. … using the CEREC Software.

Fig. 6. Due to the bright shade of the teeth in the cusp area, the restoration was positioned high in the KATANA™ Zirconia Multi-Layered Block.

Fig. 7. Surface texturing in the pre-sintered state (prior to the final sintering procedure).

Fig. 8. Bridge after a seven-hour sintering cycle.

Fig. 9. Appearance of the bridge after individualization with CERABIEN™ ZR FC Paste Stain …

Fig. 10. … and two glaze firings.

Fig. 11. Clinical situation after restoring the teeth with a lithium disilicate onlay and a zirconia bridge.

FINAL SITUATION

Fig. 12. Onlay and bridge in place (after adhesive luting with PANAVIA™ V5 and self-adhesive luting with PANAVIA™ SA Cement Universal).

Fig. 13. Final X-ray used to check for excess cement around the bridge.

Dentist:

DR. FLORIAN ZWIENER

Dr. Florian Zwiener is a distinguished dental professional known for his expertise in Endodontics, Prosthodontics, and CAD/CAM technology. Born in Cologne, Germany, he developed a passion for dentistry and pursued his education at the University of Cologne, where he obtained his degree in Dentistry. Currently, Dr. Florian Zwiener practices at the Dr. Frank Döring Dental Clinic in Hilden, Germany. Here, he continues to apply his specialized knowledge and skills, ensuring that his patients receive the highest quality of care. Follow Dr. Zwiener on Instagram: @dr.florian_zwiener.

Case report with Dr. José Ignacio Zorzin

Rationalizing clinical workflows: This is the main reason for the use of universal products in adhesive dentistry. They are suitable for a wide range of indications and different application techniques, fulfil their tasks with fewer components than conventional systems and often involve fewer steps in the clinical procedure. Universal adhesives are a prominent example.

How do universal adhesives contribute to a streamlining of workflows?

When restoring teeth with resin composite, the restorative material will undergo volumetric shrinkage upon curing. By bonding the restorative to the tooth structure with an adhesive, the negative consequences of this shrinkage – marginal gap formation, marginal leakage and staining, hypersensitivity issues and the development of secondary caries – are prevented. The first bonding systems available on the dental market were etch-and-rinse adhesives, which typically consisted of three components: an acid etchant, a primer and a separate adhesive. Later generations combined the primer and the adhesive in one bottle, or were two or one-bottle self-etch adhesives. Universal adhesives (also referred to as multi-mode adhesives) may be used with or without a separate phosphoric acid etchant.

Fig. 1. Volumetric shrinkage of resin composite restoratives and its clinical consequences.

Which technique to choose depends on the indication and the clinical situation. In most cases, the best outcomes are obtained after selective etching of the enamel¹. Bonding to enamel is generally found more effective when the enamel is etched with phosphoric acid, while the application of phosphoric acid on large areas of dentin involves the risk of etching deeper than the adhesive is able to hybridize. When the cavity is small, however, selective application of the phosphoric acid etchant to the enamel surface may not be possible, so that a total-etch approach is most appropriate. Finally, in the context of repair, the self-etch approach may be the first choice, as phosphoric acid might impair the bond strength of certain restorative materials by blocking the binding sites. By using a universal adhesive, all these cases may be treated appropriately, as the best suitable etching technique can be selected in every situation.

Apart from the differences related to the use or non-use of phosphoric acid etchant on the enamel or enamel-and-dentin bonding surface, the clinical procedure is always similar with the same universal adhesive. The following clinical case is used to illustrate how to proceed with CLEARFIL™ Universal Bond Quick (Kuraray Noritake Dental Inc.) in the selective enamel etch mode, and it includes some details about the underlying mechanism of adhesion.

How to proceed with selective enamel etching?

A clinical example.

This patient presented with a fractured maxillary lateral incisor, luckily bringing the fragment with him. Hence, it was decided to adhesively lute the fragment to the tooth with an aesthetic flowable resin composite.

Fig. 2. Patient with a fractured maxillary lateral incisor.

Fig. 3. Close-up of the fractured tooth.

Fig. 4. Working field isolated with rubber dam.

As proper isolation of the working field makes the dental practitioner’s life easier, a rubber dam was placed using the split-dam technique. It works well in the anterior region of the maxilla, as the risk of contamination with saliva from the palate is minimal. Once the rubber dam was placed, the bonding surfaces needed to be slightly roughened to refresh the dentin. As the surfaces were also slightly contaminated with blood and it is important to have a completely clean surface for bonding, KATANA™ Cleaner was subsequently applied to the tooth structure, rubbed into the surfaces for ten seconds and then rinsed off. The cleaning agent contains MDP salt with surface-active characteristics that remove all the organic substances from the substrate. The fragment was fixed on a ball-shaped plugger with (polymerised) composite and also cleaned with KATANA™ Cleaner.

Fig. 5. Cleaning of the tooth …

Fig. 6. … and the fragment with KATANA™ Cleaner.

What followed was selective etching of the enamel on the tooth and the fragment for 15 seconds. Whenever selective enamel etching is the aim, it is essential to select an etchant with a stable (non runny) consistency – a property that is offered by K-ETCHANT Syringe (Kuraray Noritake Dental Inc.). Both surfaces were thoroughly rinsed and lightly dried before applying CLEARFIL™ Universal Bond Quick with a rubbing motion. This adhesive is really quick: Study results show that the bond established immediately after application is as strong and durable as after extensive rubbing into the tooth structure for 20 seconds.^2,3 The adhesive layer was carefully air-dried to a very thin layer and finally polymerized on the tooth and on the fragment.

Fig. 7. Selective etching of the enamel of the tooth …

Fig. 8. … and the fragment with phosphoric acid etchant.

Fig. 9. Application …

Fig. 10. … of the universal bonding agent.

Fig. 11. Polymerization of the ultra-thin adhesive layer on the tooth …

Fig. 12. … and the fragment.

What happens to dentin in the selective enamel etch (or self-etch) mode?

After surface preparation or roughening, there is a smear layer on the dentin surface that occludes the dentinal tubules, forms smear plugs that protect the pulp and prevents liquor from affecting the bond. When self-etching the dentin with a universal adhesive, this smear layer is infiltrated and partially dissolved by the mild self-etch formulation (pH > 2) of the universal adhesive. At the same time, the adhesive infiltrates and demineralizes the peritubular dentin. The acid attacks the hydroxyapatite at the collagen fibrils, dissolves calcium and phosphate and hence enlarges the surface. Then, the 10-MDP contained in the formulation reacts with the positively loaded calcium (and phosphate) ions. This ionic interaction is responsible for linking the dentin with the methacrylate and thus for the formation of the hybrid layer.^4,5

In the total-etch mode, the phosphoric acid is responsible for dissolving the smear layer and demineralising the hydroxyapatite. This leads to a collapsing of the collagen fibrils, which need to be rehydrated by the universal adhesive that is applied in the next step. Whenever the acid penetrates deeper into the structures than the adhesive, the collagen fibrils will remain collapsed. This will most likely result in clinical issues including post-operative sensitivity⁶.

When applying the adhesive system, a dental practitioner rarely thinks about what is happening at the interface⁷. However, every user of a universal adhesive should be aware of the fact that a lot is happening there. This is why it is so important to use a high-performance material with well-balanced properties and strictly adhere to the recommended protocols.

Fig. 13. Schematic representation of dentin after tooth preparation: The smear layer on top with its smear plugs occluding the dentinal tubules protects the pulp and prevents liquor from being released into the cavity.

Fig. 14. Schematic representation of dentin after the application of a universal adhesive containing 10-MDP: The mild self-etch formulation partially dissolves and infiltrates the smear layer, while at the same time demineralizing and infiltrating the peritubular dentin5.

In the present case, the tooth and the fragment now needed to be reconnected. For this purpose, CLEARFIL MAJESTY™ ES-Flow (A2 Low) was applied to the tooth structure. The fragment was then repositioned with a silicone index, held in the right position with a plier and light cured. To obtain a smooth margin and glossy surface, the restoration was merely polished. The patient presented after 1.5 years for a recall and the restoration was still in a perfect condition.

Fig. 15. Reconnecting the fragment with the tooth structure.

Fig. 16. Treatment outcome.

Why is it important to adhere to the product-specific protocols?

Universal adhesives contain lots of different technologies in a single bottle. While this fact indeed allows users to rationalize their clinical procedures, it also requires some special attention. As every highly developed material, universal adhesives need to be used according to the protocols recommended by the manufacturer. In general, materials may only be expected to work well on absolutely clean surfaces, while contamination with blood and saliva is likely to decrease the bond strength significantly. Depending on the type of universal adhesive, active application is similarly important, as is proper air-drying and polymerization of the adhesive layer. In addition, care must be taken to use the material in its original state, which means that it needs to be applied directly from the bottle to avoid premature solvent evaporation or chemical reactions. When adhering to these rules, universal adhesives offer several benefits from streamlined procedures to simplified order management and increased sustainability, as fewer bottles are needed and likely to expire before use.

Dentist:

DR. JOSÉ IGNACIO ZORZIN

Dr. José Ignacio Zorzin graduated as dentist at the Friedrich-Alexander University of Erlangen-Nürnberg, Germany, in 2009. He obtained his Doctorate (Dr. med. dent.) in 2011 and 2019 his Habilitation and venia legendi in conservative dentistry, periodontology and pediatric dentistry (“Materials and Techniques in Modern Restorative Dentistry”). Dr. Zorzin works since 2009 at the Dental Clinic 1 for Operative Dentistry and Periodontology, University Hospital Erlangen. He lectures at the Friedrich-Alexander University of Erlangen-Nürnberg in the field of operative dentistry where he leads clinical and pre-clinical courses. His main fields of research are self-adhesive resin luting composites, dentin adhesives, resin composites and ceramics, publishing in international peer-reviewed journals.

References

1. Van Meerbeek, B.; Yoshihara, K.; Van Landuyt, K.; Yoshida, Y.; Peumans, M. From Buonocore‘s Pioneering Acid-Etch Technique to Self-Adhering Restoratives. A Status Perspective of Rapidly Advancing Dental Adhesive Technology. J Adhes Dent 2020, 22, 7-34.
2. Kuno Y, Hosaka K, Nakajima M, Ikeda M, Klein Junior CA, Foxton RM, Tagami J. Incorporation of a hydrophilic amide monomer into a one-step self-etch adhesive to increase dentin bond strength: Effect of application time. Dent Mater J. 2019 Dec 1;38(6):892-899.
3. Nagura Y, Tsujimoto A, Fischer NG, Baruth AG, Barkmeier WW, Takamizawa T, Latta MA, Miyazaki M. Effect of Reduced Universal Adhesive Application Time on Enamel Bond Fatigue and Surface Morphology. Oper Dent. 2019 Jan/Feb;44(1):42-53.
4. Fehrenbach, J., C.P. Isolan, and E.A. Münchow, Is the presence of 10-MDP associated to higher bonding performance for self-etching adhesive systems? A meta-analysis of in vitro studies. Dental Materials, 2021. 37(10): 1463-1485.
5. Van Meerbeek, B., et al., State of the art of self-etch adhesives. Dental Materials, 2011. 27(1): 17-28.
6. Pashley, D.H., et al., State of the art etchand-rinse adhesives. Dent Mater, 2011. 27(1): 1-16.
7. Vermelho, P.M., et al., Adhesion of multimode adhesives to enamel and dentin after one year of water storage. Clinical Oral Investigations, 21(5): 1707-1715.

Clinical Case by DT Ghaith Alousi

What does it take to reconstruct teeth according to the patient’s individual sense of beauty? Experience shows that copying nature is the secret of success. To become a good duplicator, it is essential to develop an eye for detail with regard to tooth forms, surface morphology and the internal colour structure of the teeth to be copied. In addition, the duplicator needs to develop an understanding of the materials and tools used to copy those details. The last key success factor is taking pleasure in interacting with patients.

Read the clinical case created by Ghaith Alousi and published in the LabLine magazine’s Autumn edition now and learn about his approach to creating aesthetic restorations, mimicking nature and truly individualising restorative treatments.

By Dr. Clarence Tam, HBSC, DDS, AAACD, FIADFE

The use of both porcelain veneers to improve and restore the shape, shade and visual position of anterior teeth is a common technique in esthetic dentistry. The biomimetic aim in the restoration of teeth is not only the cosmetic domain, but also functional considerations. It is critical to note that the intact enamel shell of the palatal and facial walls with respect to anterior teeth are responsible for its innate flexural resistance. When dental structure has been violated by endodontic access, caries and/or trauma, every effort must be made to preserve the residual structure and strive to restore or exceed the baseline performance levels of a virgin tooth.

BACKGROUND

A 55 year old ASA II female with a medical history significant only for controlled hypertension presented to the practice for teeth whitening. It was foreseen that dental bleaching would not have an effect on the shade of a pre-existing porcelain veneer on tooth 1.2, and that this would need to be retreated following the procedure especially if the shade value changes were significant. The patient started with a baseline shade of VITA* 1M1:2M1; 50:50 ratio in the upper anterior region and 1M1 in the lower anterior region. Following a nightguard bleaching protocol with 10% carbamide peroxide worn overnight for 3-4 weeks, the patient succeeded in achieving a VITA* 0M3 shade in both upper and lower arches. As a result, there was a significant value discrepancy between the veneered tooth 1.2 and the adjacent teeth, and also increased chroma noted on the contralateral tooth 2.2 due to a facially-involved Class III composite restoration. This latter tooth also did not match the contralateral tooth in dimension and thus the decision was made to treat both lateral incisors with bonded lithium disilicate laminate veneers. The canine adjacent (2.3) featured localized mild to moderate cusp tip attrition, but the patient did not want to address this until following the currently-discussed veneers were placed. The goal of smile design at this stage is to ultimately establish bilateral harmony with the view to place an additional indirect restoration restoring the facial volume and cusp tip deficiency of tooth 2.3 in the near future.

PROCEDURE

A digital smile design protocol was not required for the initial intention, which was individual treatment of the lateral incisors, as slight variation is permitted in this tooth type, being a personality and gender marker of the smile. Prior to anesthesia, the target shade was selected using retracted photos featuring both polarized and unpolarized selections. The photographs were prepared for digital shade calibration by taking reference views with an 18% neutral gray white balance card (Fig. 1).

Fig. 1. Reference photograph taken with a 18% neutral gray card.

The basic body shade was VITA* 0M2 with an ingot shade of BL2. The patient was anesthetized using 1.5 carpules of a 2% Lignocaine solution with 1:100,000 epinephrine before affixing a rubber dam in a split dam orientation. The veneer on tooth 1.2 was sectioned and removed from tooth 1.2 and a minimally-invasive veneer preparation completed on tooth 2.2 (Fig. 2). Partial replacement of the old composite resin restoration was completed on the mesioincisobuccopalatal aspect of tooth 12 with the intact segment maintained. Adhesion to old composite was achieved using both micro particle abrasion and a silane coupling agent (CLEARFIL™ CERAMIC PRIMER PLUS, Kuraray Noritake Dental Inc.). Margins were refined and retraction cords soaked in an aluminum chloride solution and packed. Preparation stump shades were recorded. Final impressions were taken using both light and heavy body polyvinylsiloxane in a metal tray. The patient was provisionalized and sent away with instructions to verify the shade at the laboratory at the bisque bake stage. The models prepared by the laboratory verify the minimally-invasive nature of the case.

Fig. 2. Veneer preparation tooth 1.2, 2.2.

On receipt of the case, the patient was anesthetized and the provisionals removed. The preparations were debrided and prepared for bonding by abrading the surfaces using a 27 micron aluminum oxide powder at 30-40 psi. The veneers were assessed using a clear glycerin try-in paste (PANAVIA™ V5 Try-in Paste Clear, Kuraray Noritake Dental Inc.). Retraction cords were packed and the intaglio surface of the restorations treated using a 5% hydrofluoric acid for 20 seconds prior to application of a 10-MDP-containing silane coupling agent (CLEARFIL™ CERAMIC PRIMER PLUS, Kuraray Noritake Dental Inc.) (Fig. 3). The tooth surface was etched using 33% orthophosphoric acid for 20 seconds and rinsed. A 10-MDP-containing primer was applied to the tooth (PANAVIA™ V5 Tooth Primer, Kuraray Noritake Dental Inc.) (Fig. 4) and air dried as per manufacturer’s instructions. Veneer cement was loaded (PANAVIA™ Veneer LC Paste Clear, Kuraray Noritake Dental Inc.) (Fig. 5) and the veneer seated. The excess cement featured a non-slumpy character and maintained the veneer well in place during all margin verification exercises prior to a 1 second tack cure (Fig. 6).

Fig. 3. CLEARFIL™ CERAMIC PRIMER PLUS applied to intaglio surfaces of veneers.

Fig. 4. PANAVIA™ V5 Tooth Primer application to etched tooth surfaces.

Fig. 5. PANAVIA™ Veneer LC Paste Clear shade loaded onto prepared intaglio surfaces of veneers.

Fig. 6. PANAVIA™ Veneer LC Paste immediately after seating. Note the viscous, non-slumpy nature of the cement, which allows for ease of removal under both wet and gel-phase options.

The cement was rendered into a gel state, which facilitated “clump” or en masse removal of cement with minimal cleanup required (Fig. 7). The margins were coated using a clear glycerin gel prior to final curing to eliminate the oxygen inhibition layer (Fig. 8).

Fig. 7. Excess cement removal after tack curing for 1 second.

Fig. 8. Final curing of veneers from both palatal and facial aspects simultaneously.

The margins were finished and polished to high shine and the occlusion of the restorations verified as conformative. The post-operative views show excellent esthetic marginal integration (Fig. 9).

Fig. 9. Post-operative esthetic integration of veneers on 1.2 and 2.2.

On polarized photograph reassessment, the restorations are well-integrated into the new smile esthetically and functionally (Fig. 10), now awaiting esthetic augmentation of tooth 2.3 to match the contralateral canine.

FINAL SITUATION

Fig. 10. Final result with polarized photography on reassessment.

RATIONALE FOR MATERIAL SELECTION

Porcelain is often the chosen material for prosthetic dental veneers due to its innate stiffness in thin cross section, ability to modify and transmit light for optimal internal refraction and its bondability by way of adhesive protocols to composite resin. This trifecta allows for a maximal preservation of residual tooth structure whilst bolstering its physical function relative to flexural performance¹. The elastic modulus of a tooth can be restored to 96% of its control virgin value if the facial enamel is replaced with a bonded porcelain laminate veneer². The elastic modulus of lithium disilicate is 94 GPa whereas that of intact enamel is 84 GPa. The elastic modulus of dentin has been found to range from 10-25 GPa, whereas that of the hybrid layer can vary widely, indeed from 7.5 GPa to 13.5 GPa in a study by Pongprueska et al³. This low flexural resistance range reflects that of deep dentin and not that of superficial dentin, which does not reflect an ideal situation where a laminate veneer is bonded in as much enamel as possible, or in the worst case to superficial dentin. Maximal flexural strength of the hybrid layer is invaluable from a biomimetic standpoint. PANAVIA™ V5 Tooth Primer (Kuraray Noritake Dental Inc.) incorporates the use of the original 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) monomer, which elicits a pattern of stable calcium-phosphate nanolayering known as Superdentin, an acid-base resistant zone that is about 600x more insoluble than the monomer 4-MET, which is found in many other adhesives. Indeed, PANAVIA™ V5 Tooth Primer is used solely in conjunction with Kuraray Noritake Dental Inc. PANAVIA™ V5 cement and PANAVIA™ Veneer LC which both allow the primer to act as a bond without the need to cure the layer prior to cementation of the indirect restoration due to its dual cure potential when married together. If a bonding agent would be preferred, CLEARFIL™ Universal Bond Quick (Kuraray Noritake Dental Inc.), a multi-modal adhesive that also contains the essential amide monomer and 10-MDP components created by Kuraray Noritake Dental Inc., can be used. Of note, CLEARFIL™ Universal Bond Quick features exceptional flexural strength due to the accentuated cross-linking during polymerization afforded by the amide monomers, on the order of 120 MPa by itself⁴. PANAVIA™ Veneer LC is a cement system that features cutting edge technology that provides excellent esthetics and adhesive stability of your indirect restorations, whilst allowing a stress free workflow. It is a cement system that is a game changer; one that allows you to restore confidence in the patient, strength in the tooth-restoration interface, and bolsters your clinical confidence in the delivery of biomimetic excellence.

Dentist:

CLARENCE TAM

References

1. Magne P, Douglas WH. Rationalization of esthetic restorative dentistry based on biomimetics. J Esthet Dent. 1999;11(1):5-15. doi: 10.1111/j.1708-8240.1999.tb00371.x. PMID: 10337285.
2. Magne P, Douglas WH. Porcelain veneers: dentin bonding optimization and biomimetic recovery of the crown. Int J Prosthodont. 1999 Mar-Apr;12(2):111-21. PMID: 10371912.
3. Pongprueksa P, Kuphasuk W, Senawongse P. The elastic moduli across various types of resin/dentin interfaces. Dent Mater. 2008 Aug;24(8):1102-6. doi: 10.1016/j.dental.2007.12.008. Epub 2008 Mar 4. PMID: 18304626.
4. Source: Kuraray Noritake Dental Inc. Samples (beam shape; 25 x 2 x 2 mm): The solvents of each material were removed by blowing mild air prior to the test.

Clinical Case by MDT Mathias Berger

Highly reliable implants, advanced surgical techniques and innovative restorative materials, designs and approaches: modern implant dentistry has evolved into a predictable discipline producing aesthetic and functional outcomes, which are successful in the long term. Asking patients what they expect from a complex implant-supported reconstruction in the maxilla, natural aesthetics and biocompatibility are often demanded apart from functional aspects. With modern zirconia materials that offer the flexural strength required and well-balanced aesthetics, these demands are easily met.

The following case example is used to demonstrate how to maximise the potential of the recently introduced KATANA™ Zirconia HTML PLUS (Kuraray Noritake Dental Inc.), a multi-layered zirconia and the successor of KATANA™ Zirconia HTML with further improved strength and aesthetics. A special cutback design refined with hand instruments, shading with Esthetic Colorant for KATANA™ Zirconia and micro-layering with CERABIEN™ ZR porcelains (both Kuraray Noritake Dental Inc.) led to a quite natural result.

Start now reading the clinical case of MDT Mathias Berger by clicking image below!

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!