Vita Enamic is a durable hybrid ceramic that can be processed with efficient computer-aided design/computer-aided manufacturing (CAD/CAM) support. The porous sintered feldspar ceramic block that is infiltrated with polymer does not require a ceramic furnace after being ground out. Instead, it only needs to be finished and polished. This makes one-time chairside treatment possible. In addition to the well-known monochromatic Vita Enamic blocks, a multichromatic version with integrated shade gradient and a super-translucent version have been developed. The goal of this application study is to demonstrate these new indications with their material benefits in the anterior and posterior regions using four different case studies (Int J Comput Dent 2018; (21); 3; 239-250).
Author: Harald Steinbrenner
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The basic concept behind the digital fabrication of restorations is to shorten treatment times for indirect restorations. The goal from the start was to provide patients with computer-aided design/computer-aided manufacturing (CAD/CAM)-supported restorations in a single chairside session (‘single-visit dentistry’), if possible. Materials that do not require firing in a ceramic furnace for finishing offer clear advantages in terms of the shortest possible treatment times. On average, this shortens the patient’s visit to the office by half an hour, which ultimately benefits the dentist economically and the patient in terms of time. The hybrid ceramic Vita Enamic (Vita Zahnfabrik, Bad Säckingen, Germany) has lived up to the concept of true chairside treatments since 2013. After preparation and polishing, restorations made of hybrid ceramic can be incorporated immediately. The range of indications for single-tooth restorations has now expanded considerably with the introduction of both Vita Enamic multiColor, with an integrated shade gradient, and the super-translucent Vita Enamic ST. The functional and material advantages of using hybrid ceramic remain exactly the same.
Not a composite
Vita Enamic is the only true hybrid ceramic material on the market. In contrast to other CAD/CAM materials that are also called hybrid ceramics, Vita Enamic is not a composite in which finely ground fillers made of glass or ceramic are mixed with a cross-linked polymer. Instead, the structural design of Vita Enamic is based on a porous sintered and compact feldspar ceramic block, which is then infiltrated with a polymer using pressure and heat. Vita Zahnfabrik has combined ceramics (86% by weight) and polymer (14% by weight) in an interlinked dual-network structure.1 The compound material combines the two different basic ceramic and polymer materials in a completely new way, allowing their material properties to be optimized during processing and for clinical use.2
Efficient processing – safe conditioning
The dual network allows for clinically delicate and minimally invasive restorations, compared with conventional all-ceramic materials with thin, tapered, and stable edges of up to 0.3 mm.3 Otherwise, the minimum layer thickness of Vita Enamic for crowns, inlays, and onlays is 1.0 mm. Since the material is also slightly softer than all-ceramic, the diamond-coated Cerec grinding instrument (Dentsply Sirona, Wals, Austria) is only slightly deflected during the machining process. This ensures precision and enables smoother restorations. The material does not smear, and wear for the grinding instruments is extremely low. This means that well over 100 restorations can be produced with just one set of abrasives. Even the grinding time is significantly shorter than for most conventional CAD/CAM products. For example, the grinding time for Vita Enamic is half of that required for lithium disilicate.4 After brief preparations, the hybrid ceramic with its corresponding Vita Enamic polishers can be polished to a high gloss within 2 to 3 min, and is ready for insertion. Since it is a dominant feldspar ceramic block, hybrid ceramic can be conditioned in the conventional way, similar to full-ceramic pretreatments, in the context of fully adhesive fixation using all the conventional adhesive systems. In contrast to composites, which have to be sandblasted, the application of hydrofluoric acid (5% HF) for 60 s results in an optimal etching pattern.5 The adhesive strength corresponds to the final silanization and adhesive fixation of clinically established feldspar ceramic.6
The model tooth: natural material properties
For a long time, material research focused on developing increasingly harder materials to ensure long-term clinical success. Monolithic zirconia, which has a flexural strength of 1000 MPa, can be used as an example. Natural hard tooth materials offer a much lower flexural strength for enamel (60 to 85 MPa) and dentin (100 MPa).7 As a result, according to this philosophy, many practitioners are likely to reject hard tooth materials for use in restorations, although the natural tooth is still clinically the most durable. A critical issue for long-term success could therefore lie in a completely different factor: the tooth-like flexural modulus that allows the material to compensate for chewing forces, ensuring a favorable stress distribution.8,9 The material properties of Vita Enamic are based on the natural example of the tooth. Compared to other ceramic materials, the flexural strength of 150 to 160 MPa is much lower than it is for high-performance ceramics, and is similar to the hard substance of the natural tooth. But the flexural modulus of 30 GPa also shows a value similar to dentin.10,11
In contrast, with its generally higher elasticity (9 to 14 GPa), composite does not blend as well with natural dentin from a material perspective. The biomimetic flexibility and force-absorbing properties of hybrid ceramic not only allow for longer-lasting restorations compared to brittle and rigid all-ceramic restorations, but also provide a cushioning effect12,13 (that patients often describe as very pleasant) right after adhesive fixation takes place. This prevents any uncomfortable feeling of having a foreign object in the mouth, and can also reduce unnecessary regrinding processes. During the grinding process, the dual network no longer presents the risk of microcracks, which spread and become cracks in the clinical progression, and are ultimately a major cause of chipping and fractures.14 The dual network stops the spread of cracks in the ceramic part at the interfaces to the interpenetrating polymer network.15
In general, grinding and polishing are easy to accomplish manually, something everyone who has to grind and polish lithium disilicate ceramic intraorally will appreciate. Due to its structure, the material is also more tolerant to damage in the case of severe punctate chewing loads. This is because, in such cases, it is deformation rather than so-called cone cracks that occurs, permeating purely crystalline materials from the point of application of conical crack growth.16 The abrasion of the material is in the range of fine-structure feldspar ceramic, corresponding to natural enamel.4,17 This means that a harmonious wearing effect is possible over the years, preventing functional issues in the long term. The force-absorbing property of Vita Enamic also offers a great advantage, especially in the case of implantology restorations. Since the periodontium is missing as a natural shock absorber for implants, and as these are rigidly anchored in the bone bed, the material helps to compensate for chewing forces. Bone resorption due to overloading can be counteracted, protecting the antagonizing element at a functional level.7 Vita Enamic IS (Implant Solutions) blocks with an integrated interface also enable rapid CAD/CAM-based fabrication of mesostructures on titanium abutment bases and abutment crowns that have a precise industrial fit to the titanium base.
Integrated shade gradient: Multichromatic Vita Enamic multiColor
Vita Enamic users have desired a material variant that includes a high degree of esthetics for the anterior tooth area. After all, monochrome materials do have indication restrictions when it comes to esthetics. Vita Zahnfabrik has responded to the requests from Cerec users by launching Vita Enamic multiColor. This material consists of six finely nuanced layers: two thicker outer layers and four thinner intermediate layers (Fig 1). The translucency increases steadily from the darker cervical areas to the lighter incisal ones. This creates very natural refraction properties. The transitions between the six layers are no longer discernible in the ground restoration and result in a harmonious shade gradient. Vita Enamic multiColor is currently available in the Vita System 3D-Master shades 1M1, 1M2, 2M2, 3M2, and 4M2 in the translucency level HT.
Case example 1: anterior crown
A patient presented needing treatment for tooth 12 (Fig 2). The approximately 30-year-old veneered metal crown (VMK) treatment showed a clear secondary caries (Fig 3). The crowns of the adjacent teeth were intact. The patient did not find the exposed cervical areas with the visible metallic crown margins bothersome, as the lips covered them when laughing. Since the slightly rotated tooth position was to be retained, the old situation was scanned with a Cerec Omnicam (Dentsply Sirona) before removing the crown. The quick and uncomplicated scanning process using this powder-free camera is very impressive.
In the process of the caries excavation, the gingiva injected into the caries lumen had to be removed with an electrotome. The metal pin was covered with an opaque (Paint on Color; Coltene, Altstätten, Switzerland) to avoid a gray shimmer through the crown. After reconstitution (Herculite XRV; Kerr, West Collins, USA), a classic step preparation was created (Fig 4). The maxilla and mandible were scanned with a Cerec Omnicam (Fig 5). Scanning, including vestibular occlusal registration, was going to be faster than setting an impression in the mouth. In this case, the virtual construction of the restoration was done via the Bio-Copy mode, as the shape of the crown was to be retained (Fig 6). This was followed by virtually positioning the constructed anterior crown in the multichromatic hybrid ceramic block (Fig 7). Construction using Cerec 4.5 software saved more time than creating a manually produced provisional restoration.
After the grinding process with a Cerec MC XL machine, the grinding pin on the crown was removed with a fine-grinding diamond (Komet Dental, Lemgo, Germany), and polished to a high gloss with Vita Enamic polishing wheels. The finishing of restorations is extremely fast and easy. Compared to the previous version, the new Cerec 4.5 software enables even better accuracy for fitting restorations. After hydrofluoric acid etching and silanization of the restoration (Vita Ceramics Etch; Vita Zahnfabrik and Monobond Plus; Ivoclar Vivadent, Schaan, Liechtenstein), the tooth structure was treated with etching gel (35% phosphoric acid) and bonding (Prime & Bond NT; Dentsply Sirona, York, Pennsylvania, USA), and the crown was incorporated with dual-cure luting composite (Calibra Ceram medium; Dentsply Sirona). The final result shows the esthetically perfect harmony with the adjacent crowned teeth as well as a normal and well-adapted gingiva during the follow-up check (Figs 8 and 9).
Case example 2: posterior crown
A VMK molar crown at tooth 46 showed inadequate crown margins (Fig 10) and was removed. The old build-up was removed, the secondary caries excavated, and a new build-up anchored (Fig 11). Following a typical all-ceramic crown preparation with a step, the appropriate maxilla and mandible area as well as the occlusal registration were scanned with a Cerec Omnicam (Fig 12). The virtual construction of the crown was accomplished in less than 5 min with the Cerec 4.5 software (Fig 13). After polishing, the multichromatic crown made of Vita Enamic multiColor hybrid ceramic was pretreated in accordance with the procedure described for case example 1. The tooth conditioning was performed with Prime & Bond NT and adhesively incorporated with the dual-curing luting composite Calibra Ceram translucent. Both the patient and the dentist were equally pleased with the natural effects of the final incorporated restoration (Fig 14).
Super-Translucent Hybrid Ceramic Vita Enamic ST
Until now, we have had the monochrome translucency levels of Vita Enamic T (Translucent) and HT (High Translucent). Vita Zahnfabrik has now also launched the super-translucent hybrid ceramic Vita Enamic ST (Super Translucent). The advantage of this material variant is that it can be penetrated by the shade of the residual tooth substance particularly well (chameleon effect). This makes it possible to produce restorations where there is virtually no transition between tooth structure and hybrid ceramic. This is an ideal material for preserving tooth substance with enamel-limited restorations such as inlays or onlays. The material has been available in the Vita System 3D-Master shades 1M1, 1M2, 2M2, 3M2, and 4M2 in block size 14 since February 2018.
Case example 3: posterior inlay
The patient presented with two insufficient composite fillings on the maxillary first molar (Fig 15). After the filling had been removed, the caries was excavated and an inlay preparation applied. The cavity was scanned with a Cerec Omnicam (Fig 16), and an inlay constructed using Cerec 4.5 software (Fig 17). The accuracy of fit of the Vita Enamic ST inlay immediately after sanding and the removal of the sliding pin were impressive (Fig 18). After conditioning the cavity and the restoration, as described for case example 1, the inlay was placed under dental dam with Syntac Classic and Tetric (Ivoclar Vivadent) adhesive. The intraoral polish was accomplished using brownies, greenies, and Occlubrush (Komet Dental). The Vita Enamic ST inlay was almost invisible after the finish was applied, and had integrated harmoniously into the residual tooth substance (Fig 19).
Case example 4: anterior tooth corner reconstruction
A 73-year-old patient presented with a composite filling at tooth 21 that repeatedly broke off (Figs 20 and 21). After minimal preparation, the case was scanned with a Cerec Omnicam (Figs 22 and 23). Since the Cerec 4.5 software automatically assigns the preparation form, the dentist did not have to decide between an inlay, crown or veneer. The first version of the restoration required only one minimal modification, which made quick production possible (Figs 24 and 25). After the insertion of the partial restoration made of Vita Enamic ST with Syntac Classic and Tetric, the delicate restoration was no longer discernible (Figs 26 and 27). This somewhat unusual, but extremely minimally invasive, restoration shows the high translucency of Vita Enamic ST and the possibilities of working with this material variant in areas with limited enamel.
Vita Zahnfabrik has succeeded in bringing an esthetically pleasing, robust, and genuine chairside material to the market. Since then, many situations can easily and quickly be treated using high-quality CAD/CAM support. Since the launch of Vita Enamic in 2013, it is possible for any user to produce inlays, onlays, partial crowns, crowns and individual implant restorations. Esthetic monolithic crowns, and veneers in the anterior region are now also possible with Vita Enamic multiColor. Due to the high translucency of Vita Enamic ST, partial restorations of teeth with inlays or corner abutments, for example, are indistinguishable from the natural dentition. These indication extensions of the stable-edged and easily polishable material offer real added value in everyday practice, as the new material portfolio of hybrid ceramic makes it possible to produce a very high proportion of single tooth restorations in an uncomplicated and efficient manner. Long-term stability is provided by the dual, interlocking ceramic-polymer network and the tried and tested, fully adhesive cementation protocol analogous to all-ceramic restorations – in contrast to the CAD/CAM composite variants, which are erroneously called hybrid ceramics.
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