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Whether it is nobler (wiser) to take the time to do the job appropriately or cut corners only to find that one never has the time to do it correctly the first time, but always manages to find the time to re-do it over again.
There have been great advancements in our field of restorative dentistry both from clinical as well as technological aspects. The area of implants is forever growing in leaps and bounds with new companies popping up like daisies. From the proven older systems to the newer snap crackle and pop technologies, we are being inundated with products.
With implants especially, it is of unforgiving importance that we adhere to ridged guidelines when reconstructing a single or group of prosthesis. This is important for patient comfort and function as well as for aesthetics. There is no shortcut to success.
As an old friend PKT, once said (“perfection is no trivia-but trivia makes perfection”).
The one concept which seems to have alluded all the manufactures is the design of angulation corrective abutments. i.e. those little pieces designed to correct the misaligned implant due to what ever reason. Placement can not always be exact due to many considerations which include amount of bone and density. In truth there are too many variation possibilities for any feasible pre-designed solutions. They come in limited degrees of angle and rotational correction. The end result is at best a questionable compromise.
Without question, the preliminary evaluations, design and fabrication of stints and diagnostic guides will contribute greatly to the end results. Any attempt to proceed without these is like walking blind through an unknown obstacle course. Many of us have been there. Well I need say no more.
For an aesthetic and functional restoration, the abutment design plays a major role. For a just a while now, individualized abutments have been manufactured out of titanium or zirconium dioxide for the synOcta prosthetic system RN in cooperation with the company Sirona. The dental team of MDT Thomas Lassen and Dr. Horst Lohrmann, as well as prof. Dr. Dr. Heinz kniha and Dr. Michael Gahlert, describe the use of this system with reference to a case study.
In a first visit, a 48-year-old female patient complained of the poor aesthetics of her maxillary anterior teeth. Teeth 8 and 9 were provided with splinted crowns. The gingiva showed recessions with exposed crown margins and dark, discolored roots. At the unfortunately visible apical area of the splint connection, the interdental papilla had pulled back and thereby formed an unpleasant black triangle. The shape, shade and position of the teeth in the dental arch were not harmonious with the remaining teeth. The crowns were very thick in an orovestibular direction, and the vestibular surface projected too far in a labial direction.
The palatal functional surfaces were insufficient and did not correspond to the natural tooth morphology. The problems with the restoration were particularly noticeable since the patient had a high laugh line which exposed to the entire dento-gingival interface when she smiled (Fig. 1). Clinically, the patient manifested high periodontal probe values with bleeding upon probing. The x-ray revealed advanced horizontal bone degeneration and insufficient root filling at tooth (Fig. 2). After discussing the treatment alternatives with the patient with the option of the total restoration of her dental situation, we decided as a team to remove teeth 8 and 9. To bridge the long healing phase, a stable provisional was created in the form of a model cast.
When I was fresh out of Dental Lab School, and hired as a dental technician in a small dental laboratory, I remember what my boss said to me my first day. He said “Son, if you plan to make a career as a dental technician, you will realize that a normal day does not go by unless something goes wrong. And if by the end of the day, you feel everything went right, check your sources because something is probably wrong somewhere”. Well, it is 33 years later, and I am glad to say that everyday wasn’t as bad as all that. Sure, there have been many days like that. We’ve all had them. Days when you don’t know when you’ll be home for dinner due to a remake, or some kind of mishap that couldn’t wait till the next day to fix. Needless to say, these mishaps cost time and money for the lab, and frustrations for you, the technician.
It is a tedious occupation we chose for ourselves, and we are trained professionals. We work with technique sensitive materials that require enormous amounts of skillful techniques to master in order to achieve favorable results. When we achieve these results, we take pride in what we’ve accomplished. We do this everyday, and we love it because we would not be doing it if we didn’t. The key words here are “technique sensitive”. What in this industry is not technique sensitive? We are intelligent human beings, not computerized machines so when repetitious mishaps occur in the lab, we have to stop, and look at such things as:
• Materials: Am I using the proper materials to complete the restoration? Am I getting the most out of them by following manufacture’s instructions?
• Technique: Am I using proper techniques to achieve a quality restoration?
• Rushing: There is nothing wrong with taking a short cut or two in order to save time. However, too many shortcuts will affect the final outcome, and jeopardize the quality of the completed restoration.
• Careless: There is no forgiveness for being careless when working in this industry. Mishaps are practically guaranteed if care in what you do is not taken into consideration.
There has been a lot of literature written about the complete denture technique; however there has been little improvement in this technique over the years. This concerns not only the performance capacity in dental medicine and dental technique, but more specifically the performance capacity for the complete denture technique.
It is deplorable that people receive restorations which are partly unsuitable for them; especially for those where restorations are absolutely necessary.Fabricating a ceramic crown can be a challenge for dental technicians when they are unable to use the rest of the teeth for guidance. In order to rebuild a system in a toothless mouth (black hole), a high degree of practical and theoretical knowledge is needed. The system is used for mastication, it demands aesthetics, and plays an important contribution to the stability of the whole body. This situation establishes the need for real experts.
In the first part of the article we discussed the fabrication of the wax-up in detail and created the groundwork for the following steps. The wax-up is the foundation for the work from here on. It took some time, effort and skill to achieve a good base for the definitive restoration but it pays off in the long run. In the article below the wax-up will be changed to the actual restoration. The making of the framework will be an easy step. Metal or zirconium dioxide – the process stays the same. The author describes his workflow from the wax-up to the restoration.
Index: Aesthetics, Metal Ceramic, Morphology, Surface Work
After the patient and the dentist agreed on the form and function of the wax-up (Fig. 1), the silicone key was made. This tool can be referred to for the rest of the work process.
For the framework model the wax-up is the ideal basis because it only has to be reduced to the smaller crown shape (Fig. 2). This will produce an ideal frame design the fast and easy way and the caps will have a circular metal margin. If the impression is flawless this step can be eliminated which is more cost-effective. When it comes to natural color choice the circular steps in ceramic are unbeatable. In the case of occlusally screwed bridges I would like to point out that I always blend 2mm into the screw canal. A wise decision from an esthetic point of view; of course this step has to be considered during the making of the framework.
The next step is the intra-oral trial in the patient’s mouth. It helps us to control the bite. The completed framework has to have at least four plastic abutments, in my opinion six are even better. Whenever large frames are used I make a point to be present during the fitting.
High quality is not enough anymore; price is ruling the market. Such circumstances brought Michael Brüsch, MDT, known for his high quality and bio-aesthetical build up technique, to find an alternative.It was urgent to find, for the very busy and cost-conscious laboratories, a method which makes it possible to produce high quality, aesthetically satisfying restorations, with out having to invest a large amount of money, and at the same time, make a product that has an attractive price for the patient. In Germany it is important to remember that all laboratory work is charged in an open bill to the patient.With GC’s new product line GC Initial-IQ-The One Body System- the technician, as well as the patient, have found an aesthetic but also cost-effective alternative.
Indications: Press-Over, One Body, 3 dimensional Luster paste
IQ is a new concept for the press over technique of metal and press over Zircon-oxide frames. Not only is it possible to fabricate posterior teeth with this special Layering Technique, but also anterior teeth.
Not only did the company succeed in producing a pellet (ingot), which has the traditional qualities, like Chroma (Dentine) and Fluorescence, but also a special effect using light dynamics for the anterior teeth to create a 3 dimensional result.
This allows the laboratory to produce high quality crowns and bridges with a full anatomical wax up. With this ingenious technique, and new materials, it is easy to achieve results, which are high in quality similar to those fabricated with the build up technique, in Vita Classical shades.
The known disadvantages of the press techniques where solved with the following process of production. Until now, it was necessary to cut back pressed anterior teeth and layer with powder to achieve acceptable results. For the posterior teeth, it was necessary to stain and glaze several times (up to four times) to achieve acceptable results. With the new IQ system, It is sufficient to bake only once! The exception to the one firing process is the pressed over Zirconia which needs two firings to achieve the three dimensional results you are looking for.
In this contribution, we experience the reconstruction of the maxilla, anterior teeth, 13 to 23, and the creation of single crowns with Zircondioxide copings. Many articles about Zircondioxide miss the emotions, which are associated with this material. Often, the tremendous strength and color stability of the white substructure are discussed, yet the handling of the material is rarely examined. This article will further discuss the importance of handling various types of materials. When we use Zircondioxide, investing, casting and finishing of the frame are eliminated. The combination of the frame material with the right ceramic makes veneering an emotional experience.
Indications: Single crowns with Zircondioxide, the copy milling system, the wax up and the Zircondioxide veneering material.The Zircondioxide copings come warm out of the sinter furnace; this is one of the nicest acquisitions of this material. Zircondioxide is a functional material and is adequately used in prosthesis and aesthetic veneering.
The patient has very large fillings and wanted to change his anterior teeth with Zircondioxide crowns. The patient’s expectations are: an aesthetic, long lasting restoration.
Example: A long-span bridge was planned to be fabricated as an all-ceramic bridge. However, limited tooth preparation changes the outcome. Instead, the bridge is fabricated as a 100% biocompatible metal ceramic bridge. This technique can be used on natural or implant abutments.
To keep the natural appearance and reflection, the copings are fabricated with the Galvano Technique which is completely biocompatibility. For the framework connecting the abutments, a strong alloy should be used. 1) Using a base metal gives the ability of casting as thin as 0.2mm. Precious alloys need a frame thickness of at least 0.3 to 0.4mm depending on the alloy (this takes space away for the ceramic).
2) A strong base metal allows the connectors to be thin (2mm). This allows more space for us to cover the metal substructure with ceramic. All-Ceramic bridges require thicker connectors to avoid breakage. With most cases, the space required for all-ceramic bridges is non-existent. Therefore, the finished bridge will be 100% biocompatible and look at least as natural as an All-Ceramic bridge.
3) The Galvano-bridge is processed like an All-Ceramic restoration but without stress in the framework. The separate copings and cast pontics can be joined using three different techniques:
To understand those different techniques easily a demo model was fabricated with the necessary pure gold copings produced with the Gammat Free unit from Gramm Technologies.
The firing stability or the resistance to deformations of a dental alloy becomes a very important issue when implant supported and screw retained cast frameworks have to be created. This is due to the fact that implants with good bone incorporation do not have the mobility known with natural teeth and thus the accuracy of fit of a cast framework becomes mandatory for a successful restoration. Furthermore, the larger the extension of a bridgework cast in on e piece becomes, the greater the difficulty gets to maintain the accuracy of fit achieved after casting until the last firing cycle for the ceramic.
The preferred framework materials used for implant supported restorations such as ceramic-fused-to metal alloys or mono metals like titanium do contain certain amounts of processing errors or can only be used together with a profound know-how in processing procedures in this special field of restorative dentistry in order to get successful restorations.
This goes especially for high gold content alloys together with spans and sizes exceeding the normal dimensions. These large implant supported bridgeworks, cast in one piece are especially difficult to realize and the 100% “passive-fit” rarely occurs.
Ingenious systems like spark-erosion or copy-milling exist on the market and offer the correction of non fitting frameworks to the implants. Unfortunately, these systems are too expensive for a large majority of dental labs. The same counts for the CAD/CAM systems, which allow an almost cost-effective processing of “cheap” non-metallic materials or titanium.
This has been our background for the development of a high gold alloy especially recommendable for implant supported restorations under consideration of all relevant processing parameters in order to find the best possible variant under the tested alloys.
In the first part of this article, the author talks about the “Press-over- technic in combination with the staining technic”. He was using as an example a three unit bridge with a metal margin and a bridge fabricated with this combination technique. The second part the technique on the pressed over metal ceramic in combination with the build up layering is produced.
Indications: Combination of metal-ceramic and Press-over, Press ceramic, Press-over (pressed ceramic over metal frame) Staining Techniques, layering Techniques and Combination Technique.Layering technique
The second part of this article is concentrating on the pressed to metal ceramic with the combination of layering porcelain. It is our opinion that this technic has big advantages: the quick fabrication of one or more precise ceramic margins, then the individualized layering with precise control from start to finish of the work. The dentist orders a high level aesthetic crown, since the patient sought the treatment because of aesthetic reasons. Since the crown is located in the posterior region an all ceramic crown was out of the question; furthermore, the amalgam filling would have posed a negative influence on the end result. (fig70) A crown with a galvano coping could have been fabricated, however , since the shoulder preparation was such that it allowed us to fabricate a 360° ceramic shoulder, we chose to produce a press-over metal crown which then in second level would be layered with porcelain. (fig. 71to 81)
During the procedure of choosing and assessing a precious metal alloy for metal-ceramic restorations, our clients mostly focus their attention to the alloys Vickers hardness, its colour and of course the Coefficient of Thermal Expansion (CTE). The higher the hardness of this type of alloy (indicated in the state after firing) the likelier is the acceptance. In the same process, less or even no attention is being paid to other important physical and mechanical properties such as the solidus-point of the melting range and the values of 0,2 % proof stress (Rp 0,2%) in the state after firing. These values are (besides the hardness) directly connected with the expected performance in stability and accuracy of fit of a pfm-alloy during the ceramic firing processes.
The Solidus-Point (TS) in °C of a pfm-alloy is as important as the CTE. This is due to the fact that the greater the distance between the TS and the highest ceramic-firing temperatures is, the resistance of the cast framework to deformations at high temperatures will grow. When using classic high fusing ceramics, whose firing temperatures normally begin at 980-950°C, the difference to the alloys TS should be at least 100°C.
About 11 years ago, some ceramic manufacturers took action against the too low distances between the highest firing temperatures of the then available ceramics (980°C) and the low TS of the famous yellow and palladium-free alloys (<1020°C) by creating a new generation of “low-fusing” ceramics having the same medium CTE, but offered lower firing temperatures (900°C and below). The change to one of these new ceramics often helped the users of golden yellow and palladium-free AuPtZn-alloys to considerably reduce the deformations of the frameworks during the ceramic firing cycles.
In the meantime, this generation of ceramics with lowered firing temperatures have become an irreplaceable alternative to the classic high fusing feldspatic ceramics.
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