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Automated engineering and manufacturing are no longer unimaginable in handicraft fields; they began to penetrate years ago. In dental technology, however, where every restoration is unique, it was hard to imagine until recently that CAD/CAM technology belonged in the laboratory. But zirconia and the extremely rapid development of computer software and hardware changed all that. This process for automating labor-intensive routine jobs has become highly competitive on the global market. The case report below teaches us that this technical progress is no longer weighed down with huge investments—the dental laboratory can outsource part of its fabrication process to a milling center.Case Report
The patient, an 18 yr-year-old student, suffered from aplasia of both lateral maxillary incisors (Fig.1). The original treatment plan proposed to her was to treat the edentulous areas with single implants. After the orthodontic treatment was complete, it was discovered that implants would not be possible because of the angulations of both canines and the resulting convergence of the roots of the central and lateral incisors. The patient was then treated with an intermediate partial denture to replace teeth 7 and 10, which of course badly compromised her esthetic appearance. It constituted a severe emotional handicap for a girl of her age (Fig. 2). Since the patient was offered no satisfactory solution, she decided to change dentists. What treatment options would you now consider for her?
Laboratories today have a variety of CAD/CAM allceramic materials to choose from when seeking to fabricate efficient single-unit restorations. However, when it comes to ensuring esthetic compatibility and consistency as well as productivity, simplicity may be sacrificed. The IPS e.max® all-ceramic product line is a universal system for CAD/CAM and pressable fabrication techniques that can satisfy multiple indication case needs no matter what the patient’s expectations and requirements are for esthetics or function. What’s more, it doesn’t matter whether the restorations are being placed in the anterior or posterior segment, if it can and should be done simply, then IPS e.max makes it possible. For single-unit restorations with no special requirements, IPS e.max® CAD may be the material of choice for esthetics, efficiency, and virtually effortless fabrication.
Machined zirconium frameworks have for some time been part and parcel of the daily routine in many dental laboratories. The precision and productivity of this material has been enhanced in recent years to meet higher standards. A sort of wait-and-see response, however, has been noticeable most likely because the market has experienced immense growth in new systems. This abundance of choices now requires a certain basic knowledge to confront the terminology, for example, green compact, HIP zirconia and the variety of scanning processes. But once the frameworks are fabricated and a certain normalcy returns, the question still remains: “but veneered to what?”
Although ceramics have been used for purposes other than intended, such as with titanium, many innovations have also been created in the field of veneers. Almost every manufacturer offers a matching ceramic for its framework, which of course does not imply that the framework must always been veneered with a specific ceramic. Just as in metal-ceramic work, we have a CTE for frameworks and related product usually remains independent of the framework material – and works out well for the dental technician. Every laboratory has its own favorite ceramic system, usually a reflection of a particular personal philosophy. It is with this background in mind that I tested and reported on a new veneer system from Ivoclar Vivadent. Dr. Daniel Edelhoff worked with me on this project.
The high-performance ceramic, zirconia, has recently established itself solidly in the line-up of dental materials. The chemical and physical properties are exceptionally suitable for framework fabrication in the fixed-denture field. The most challenging aspect is working with the material because we must leave our old ways behind and are faced with an automated manufacturing process. We need to possess creativity and persistence at this interface between handiwork and automated processes. The following report will launch a discussion on whether these demands can be incorporated into the laboratory routine.Why All-Ceramic?
Many people still see metal-free restorations as a fall-back solution whenever specific conditions affecting either the patient or clinician create a problem for using metal. The use of allceramic crowns or bridges still remains a niche interest and is currently not rated very highly. But if both techniques, i.e., metal-containing and metal-free, were instead presented as equivalent alternatives, then I believe most patients would prefer the metal-free solution. The comparison requires, of course, that some general criteria are equally well met, such as:
The use in dentistry of endosseous root form implants presents unique challenges when they are part of an aesthetic restorative plan. Adequate soft and hard tissue supporting tissues must be managed to permit the emergence of the restoration from a submerged fixture in a way that mimics nature. Paramount to success of the restoration is the achievement of the ultimate aesthetics achievable. This case report illustrates the grafting of an edentulous ridge in the upper cuspid and bicuspid area, provisionalization during several phases of healing, implant integration and a CERCON® (Dentsply) bridge as the definitive restoration for optimal blend of strength and aesthetics.
Endosseous root form implants were introduced over 30 years ago. Since then, techniques to permit their use in situations which are demanding aesthetically and functionally have evolved. Especially in the aesthetic zone, the clinician must plan and manage many unique restorative issues when implants are involved (Ref. 1,2, 3) including:
• The location of the implant fixture in three planes of space for optimal soft tissue support, especially in the interproximal papilla zone and on the facial aspect
• Alignment of the fixtures to permit use of abutments which draw when used for splinting adjacent abutments
• Emergence of the restoration from the soft tissue to emulate natural dentition
• Ability to conceal the abutment with the restoration or with soft tissue coverage
• Occlusal design to support remaining natural dentition without putting excessive stress on the implant fixtures or the abutment connections to them
Well kept teeth and an appealing smile come in first place in terms of attractiveness. Thanks to brand new technologies and high-tech materials the patient’s desire for beautiful teeth can easily be realized. In this particular case, a 52 year old female patient presented. After detailed examinations and analysis we decided that a complete restoration of the maxilla and mandible with bridges on implants was required. By using zirconium dioxide for the frameworks we could meet the patient’s wish for a fully biocompatible restoration.
Proper planning is essential with every piece of dental work, especially in regards to aesthetics. As a first step, we have to undertake an analysis of the actual dental status. Secondly, we have to think about the desirable result. The third step is to define the necessary procedures of treatment. In this connection we want to emphasize that the cooperation between the Dentist, Dental technician and the patient is absolutely necessary to achieve a positive result. Slogans like “Beautiful Teeth Within 2 Hours” lead patients to have misconceptions of what is meant by modern, patient-oriented, responsible dentistry.
Patient: Age 52, female. We think there is no further comment necessary on the aesthetic and functional aspects of this absolutely disastrous situation (Fig. 1 and 2). In the first treatment unit we removed the bridges, extracted teeth numbers 22, 23, 24 and 17 and started to augment the alveolas with Beta-TCP (Ostim) and supplied the patient with a temporary bridge (Fig. 3). In the second treatment unit we extracted teeth numbers 31, 32 36, 41, 42 and 48. Similar to the measurement in unit 1 we augmented the alveolas and supplied a temporary bridge for the patient. We extracted teeth numbers 11, 21 and 14 and implanted Wi.tal implants with immediate loading function. One week later we implanted in region 31 and 32 another 2 implants (Fig. 4)
Copy milling is an easy and economical method to produce zirconia frameworks for dental restorations. From the technician's point of view, this precise technique comprises well-known work processes, e.g. modellation and manual milling. Thus, only a short introduction period is required to learn how to produce highly accurate ceramic frameworks. All production steps are uncomplicated and easily understandable. Furthermore, the experience of the dental technician has a positive effect on the production process. The user of the copy milling technique also benefits from a similar flexibility than in the casting technique, e.g. expansion control as well as delicate framework design up to fully anatomical crowns. This report shows the complete production process from the model preparation to the finished porcelain-faced zirconia framework.
Key words: all-ceramic, zirconia, technique, copy milling, Ceramill Thanks to the advantages of an all-ceramic, metal-free and at the same time very sturdy dental restoration, the high-performance ceramic zirconia has quickly gained an excellent reputation in the dental field. The knowledge that almost any type of dental restoration can be realized with this material offering long durability and utmost fitting precision caused a run on this ceramic framework material and the according technology. Although many dental technicians have a great interest in using zirconia as material for their frameworks, they have hesitated so far to invest their money in the relatively expensive CAD/CAM production technology. Reasons, which so far scared off the prospectives from buying such a system, were a high financial risk as well as the necessity to learn the comprehensive use of the new software for framework design.
In this regard, the copy milling technique (e.g. Ceramill by Amann Girrbach GmbH - see fig.1) is a reasonable means to finally start with the production of the very popular zirconia frameworks.
With the extensive usage of CAD/CAM systems in the dental laboratory, it is apparent that three different variations of the system are most commonly used.
The first system used, is the small cost-efficient system which has manual controls to manufacture Zirconiumdioxid (Ceramill, ZirkonZahn). The initial investment cost involved with this machine is relatively low; therefore the financial risk of an erroneous decision is tolerable for many labs. It is also very easy to integrate these systems into existing laboratory procedures. The models and patterns are manually produced in wax or plastic subsequently, instead of casting them; the patterns are manually scanned and milled by use of these machines. These are all techniques which are already commonly used in labs today. The Systems are only restricted to one material, the presintered Zirconium Dioxide. These systems prove beneficial in producing a small quantity of restorations but are insufficient when producing large quantities. It is important to understand that when productivity increases, the need for adequate staff and machinery also increases. The cost factors involved and the degrees of quality will vary dependant on the quantity produced and understanding that the results of manual activities are always variable.
Other popular CAD/CAM Systems are the following computer aided manufacturing systems; (3M, Cynovad, DCS, Hint-ELs, Kavo, Noritake, Sirona, Wieland). These systems are much more expensive when compared to manual systems. Costs can be dramatically increased due to the necessity of using new technologies such as scanners, special software and special production equipment. Also required will be intensive instruction as well as modifications to internal logistics in the laboratory. These current developments in technology lead to more efficient but also more expensive manufacturing systems. (Figure 2) Fully automatic milling systems for ceramics and plastic machining and laser melting systems for metal machining give promise to a higher capacity of frame work while minimizing staff. (Figures 3,4) The ability to run a 24 hour production facility as found in some consumer goods industry products can be realized. Essentially, quality can be restricted by quantity of orders to be filled in limited time. Without the advent of sophisticated and expensive machines, effectiveness at a controlled lower cost can not be achieved.
This case involved a 63-year-old Caucasian female who was a former dental assistant, now retired. She presented to her dentist’s office with a failed root canal on tooth #4. This tooth was subsequently extracted, and rather than have an implant or flipper, she decided on a 3-unit fixed bridge that would span teeth #s 3 and 5 with a pontic in the middle. The patient wanted something strong and permanent, so the decision was made to place an all-ceramic yttriumzirconia (YZ) framework as the substructure, layered with VITA VM9 porcelains.
We had worked with the prescribing dentist for years, and he was familiar with our all-ceramic restorations produced with the inLab System. He requested the bridge be made using the strongest substructure material available, yttrium-zirconia, which has also become known as “white steel” in dental circles due to its combination of excellent esthetics and extreme strength. Although we could have designed and milled the framework for this case using our inLab System, YZ restorations require a special high-heat molybdenum-rod furnace capable of producing temperatures of up to 1500º Celsius (2732ºF) for extended lengths of time. Our lab is relatively small, consisting of a waxer, a removables technician and a model person. My father, Rex, and I concentrate on all of the inLab cases and ceramic work. At this time, it is not economically feasible for us to purchase a dedicated YZ-sintering furnace. However, YZ restorations are becoming increasingly popular, and there may come a time when demand becomes great enough that the purchase of such a furnace would be right for us. Until then, we will send our YZ restorations, such as this 3-unit bridge, to the infiniDent service.
The infiniDent service allows us to provide our customers with the high-strength, highly esthetic single- and multiple-unit YZ restorations they prefer without the need to purchase an expensive zirconia-capable sintering furnace. We do not consider infiniDent as outsourcing in the traditional sense of the word because, with it, we retain total control of the design of the restoration. We’ve designed the restoration fully; it is simply being fabricated to our exact specifications at the infiniDent facility. We like to think of it as “expanding our workbench,” both virtually and literally speaking.
For a long time we technicians had been longing for metal restoration coming out of the sinter furnace perfectly fitting the model. This desire, however, is unlikely to come true after consecutive firings especially in case of implants. Nevertheless, the dream can come true if zirconia is used.
Zirconium was discovered in 1789 by the German Martin Klaproth and isolated by the Swedish J.J. Berzelius in 1824. Zirconia is a silicate whose composition is Zr(SiO4). It is obtained from a mineral and is one of the most abundant elements in the terrestrial crust. Chemically very reactive it is mainly found combined with oxygen forming zirconium dioxide (ZrO2). Zirconium is used as coating on nuclear fuel parts, for photographic flashes and for the protective slabs of space shuttles.
In the last decades zirconium has been successfully used for artificial limbs and joints in the medical field. The material is considered biologically and chemically inert. Due to the small diameter of its grains a very polished surface is obtained which explains the reduced accumulation of plaque and the excellent tissue tolerance. Like any other metal zirconium is radiopaque and thus allows us by means of x-ray to check its marginal adjustment. It has better mechanical properties than aluminium, especially as far torsion and traction is concerned.