IPS Empress CAD by Ivoclar Vivadent
Tooth Preparation GuidelinesFor many years tooth preparation for metal supported ceramics was as varied as the clinician who performed them. Metal can be cast into any configuration imaginable including sharp angles and tips. It is also strong enough to be polished to a thin edge to accommodate a knife edge margin preparation.All-ceramic restorations require a totally different mindset when preparing a tooth. Whether the crown is made by press technology or by CAD/CAM technology the guidelines are still the same.1. First and foremost requirement is a smooth preparation. Remember, ceramic crowns are a type of glass and any sharp angles or corners create stress points that can lead to fractures.2. Uniform reduction is necessary for optimal strength and esthetics. Once again, thin areas compromise strength and esthetics.Remember Uniform reduction results in optimum ceramic strength Adequate reduction leads to better esthetics Smooth edges result in lower stress Lower stress decreases potential for fracture Ceramic restorations require a passive fit Scanners read smooth preparations more accuratelyGuidelines Uniform, circumferential, tooth reduction of 1.0-1.5 mm Circumferential chamfer margin Occlusal reduction of 1.5-2.0 mm Rounded line angles Reduce linguals of anteriors with football diamond to create concave lingualAnother very important point to understand is how crowns are milled with CAD/CAM. The preparation needs to be smooth for an accurate scan, but also so the milling burs can reach every area. The burs used are 1mm in diameter at the tip. If the preparation is left with a sharp incisal edge or sharp line angles on the axial wall, or even sharp irregularities on the margin the burr will not be able to reach into those areas leaving a crown that will not seat completely.We hope these guidelines will help you.At Oral Design Dental Laboratories Inc. we have been working with all-ceramic restorations for over 25 years.Feel free to contact us with any firstname.lastname@example.orgCustom Implant AbutmentsDental implants have become so common place that I’m sure most dental practices deal with them on a daily basis. Even if you are not placing the implant, you are doing the restorative work over top of them. Working together with a knowledgable lab is important because at times implant work can get a little tricky. For the majority of cases a stock abutment from the implant manufacturer will work fine, but many times a custom manufactured abutment can improve the case and sometimes may even be a necessity. Lets discuss a few reasons why you may want to consider a custom implant abutment.Emergence Profile-a narrow diameter implant can leave a severe emergence profile. Some manufacturers refer to this result as an “apple on a stick”. Do you get the picture? A custom abutment can create a much more natural emergence profile for the restoration or in the case of anteriors a more naturally shaped root form instead of just round.images courtesy of Astra Tech Over-Rotation-some implants need to be inserted and torqued so that a specific spot is facing the buccal. For example the Nobel Replace Select has an internal triangular fit. It is very obvious in the lab when these implants are over-rotated. (See the photo below). On a regular basis we see these implants over-rotated. If the restoration can be done with a straight abutment then it’s not as big of a problem. We use a stock abutment and trim all the margins to adapt to the new orientation. If the case calls for an angled abutment then a custom abutment is absolutely necessary in order to correct to rotation so the angle is proper. Severe Angulation or Placement-sometimes implants just end up on a difficult angle and sometimes they have to be placed in a tough to restore location. This is definitely when a custom abutment is always necessary. There is no way stock abutments will work and often we have to get very creative just to make a custom abutment. At Oral Design we work closely with Atlantis™ by Astra Tech to create custom abutments for your cases.With Atlantis VAD™ (Virtual Abutment Design) software, abutments are uniquely designed from the final tooth shape for a more natural esthetic result. Atlantis™ abutments are available in zirconia, titanium or gold-shaded titanium. All Atlantis™ abutments are covered by a full universal warranty.We also use our InLab CAD/CAM system to create custom zirconia abutments and at times we will even wax and cast a custom abutment in gold to get it just right.We hope this helps you understand a little more about custom abutments. If you have more questions feel free to respond to this blog or just give us a call.Monolithic crowns have definitely become the buzz word of the dental industry in recent months. By definition “monolithic” means it is fabricated in full contour out of a single material. Traditionally crowns are made with a strong substructure of metal or zirconia. Both of these materials are very strong and virtually unbreakable. These substructures, or copings, are then veneered with a porcelain to full contour to give esthetics and function. If fabricated properly these restorations can function for many years, however they can fail due to two inherent weak spots. The interface between the coping and the porcelain veneer, and the veneering porcelain itself (90-110mpa) are both much weaker the coping itself. If anything is going to give it will be the porcelain itself.A monolithic crown eliminates the layer of a weaker porcelain over the crown thereby making the crown much stronger.The two options available for monolithic crowns right now are IPS e.max, and Full Contour Zirconia restorations.IPS e.max Lithium Disilicate is a “monolithic” glass ceramic restoration. It offers dentists improved fit, improved esthetics, and improved durability (400mpa). Metal, zirconia, resin, and conventional feldspathic porcelain still have an important role, but e.max is perhaps the most versatile and chip resistant option available. It can be “pressed” or milled using a CAD/CAM system into full contour. It has no interface, and no layered veneer. And because the ceramic ingots are blended with dentin colored and translucent ceramics, these posterior crowns match posterior dentition with slight translucency in cusp tips. They are customized with paint-on shades and then a layer of glaze for a final shine.Full Contour Zirconia is exactly what it says, a crown made to full contour of solid zirconia. Although much less esthetic than e.max, it is far stronger (800-900mpa) and therefore well suited to withstand severe parafunctional activity. With these virtually unbreakable crowns, you can offer your patients the strength to withstand severe bruxing and avoid metal restorations. These crowns can only be made by CAD/CAM. They are milled from a block of “green” zirconia, infiltrated with a special coloring liquid and then sintered at 1500 C in a special oven. They are then customized with paint-on shades, polished, and then covered with a layer of glaze for a final shine.Personally, I see the demand for monolithic crowns growing every day. E.max is such a versatile material and is only getting better. It is available in various levels of translucency and all the Vita Classical shades. It is also perfect for thin or “no-prep” veneers because of it’s strength, and when a layer of translucent porcelain is applied to the labial it results in an extremely esthetic restoration. (see our gallery) I have seen very few failures with e.max and in my opinion they can all be attributed to not following preparation guidelines (see our resources page) or experimenting with bridges in locations not indicated.Full contour zirconia is surprisingly popular also. It is not the most esthetic option but it is very strong, and so a great choice for posterior teeth. I am told newer, more translucent zirconias should be showing up soon but until then ours are looking pretty good. We’ve had a few glitches getting these crowns to this point, mostly a defective sintering furnace that would leave the crowns looking very opaque, but now with a new furnace we feel pretty confident in full contour zirconia. Make sure you know what you are doing with zirconia because it is such a hard material. You don’t want to have to cut one of these suckers off. Also, if you need to adjust the occlusal surface you MUST polish it back to a high shine or it can be very abrasive to the opposing tooth.At Oral Design Dental Laboratories Inc. we offer both e.max & full contour zirconia crowns.I get the sense already that 2012 is going to be a great year. Consumers seem to be confident, dental offices are busy and we are excited to be a part of it all. Oral Design has taken a big leap. After 28 years in business Jerry has taken on a partner in the lab by the name of Monty Jensen. Mont brings a fresh enthusiasm for the business that can’t help but rub off on everyone. Visiting your offices, sponsoring courses and of course writing a blog are a few of the things we hope you’ll enjoy in the coming months.With the blog we hope to keep you informed on everything from new materials and techniques, to photos of your work in progress. We hope you will take the time to read it and leave comments. We need your input.Best of fortunes in the New YearJerry, Mont and everyone at Oral DesignWelcome to OralDesign.ca blogIn the coming months our goal is to publish blogs on topics that we hope will be pertinent and helpful to your dental practice. Any comments or suggestions are welcome.
IPS e.max CAD This product forms part of our “All-Ceramics” field of competence. All the products of this field are optimally coordinated with each other. Video: IPS e.max CAD Hammer crash TestVideo: e.max Ivoclar Tabelle : Cristallization Parameter e.max CADAdvantagesHigh strength (360 MPa) and high esthetics Efficient, economical processing due to easy milling properties Minimally invasive restorations Three levels of translucency for maximum flexibility One day for a completed posterior bridge with outstanding overall strength (supported by zirconium) Adhesive, self-adhesive or conventional cementation depending on the indicationIndications(Thin) veneers Minimally invasive inlays/onlays (1 mm) Partial crowns and crowns 3- to 4-unit bridges (IPS e.max CAD-on technique) implant superstructuresAuthorized CAD/CAM Partners IPS e.max CAD is an innovative lithium disilicate glass-ceramic (LS2) block for the CAD/CAM technology.IPS e.max CAD blocks are suitable for the efficient fabrication of esthetic high-strength single-tooth restorations, such as veneers, inlays, partial crowns and crowns. In combination with IPS e.max ZirCAD (ZrO2), the innovative IPS e.max CAD-on technique now also permits the fabrication of up to 4-unit posterior bridges with outstanding overall strength.The IPS e.max CAD lithium disilicate (LS2) glass-ceramic is processed in a "soft" intermediate state, in which the material demonstrates its characteristic and striking bluish colour. In this way, manual adjustments or a cut back can be quickly and efficiently carried out and the accuracy of fit can be checked. This is followed by a simple and quick crystallization process (approx. 20 min), in which the material obtains its final strength of 360 MPa and the desired esthetic properties, such as tooth shade, translucency and brightness. IPS e.max CAD can be designed to full contour or used to fabricate frameworks (veneering with IPS e.max Ceram). DMC Cologne Kuselerstr.1 50739 KÖLNEin Fertigungsbereich der Wallossek Dentaltechnik GmbHGeschäftsführer: ZTM Frank WallossekTel.:0221/917466-32 / Zentrale: Tel.:0221/917466-0GF/ Phone: 0173/5667766STL-Datenversand an: email@example.com www.dmc-cologne.com