On Saturday December 20, 2014 we lost one of the most influential individuals in the history of dentistry. Per-Ingvar Brånemark. Born May 3, 1929, Dr. Branemark was a Swedish orthopedic surgeon and research professor, often referred to as as the "father of modern dental implantology." Later, the Branemark Osseointegration Center (BOC), was founded in 1989 in Gothenburg, Sweden.
Dr. Branemark founded osseointegration serendipitously through a study being performed to determine best protocols for drilling bone. He was drilling sites in rabbits and placing a titanium optical chamber in the leg. Later, observing bone regeneration over time through microscopic examination through the titanium optic chamber, he discovered the optical chambers were not retrievable. Hence, osseointegration had occurred and been discovered. Most dental professionals have no idea that this finding took place in 1952 when Branemark was just 23 years old. In 1982 Dr. Branemark introduced the Branemark implant system to the world. Along with Nobelpharma the system became the first highly successful dental implant know to dentistry.
The earliest attempts at dental implant tooth replacements on record were discovered in the Mayan civilization dating back to 600 A.D. Archaeologists have recovered ancient skulls in which teeth were replaced by materials ranging from carved stones, such as jade, to fragments of seashells. So, Dr. Branemark was not the first to demonstrate the desire or need for dental implants, he was however, the founder of what had become the first truly predictable solution for implants and tooth replacement. This has resulted in a life changing experience for millions of people.
For all of us that have been involved in dentistry for any significant period of time, Dr. Branemark’s discovery and subsequent inventions have had a profound impact on our profession. So many of us have played a significant role in Dr. Branemark’s dream. In my opinion, this has been the greatest discovery in dentistry in our times. There is no question we will miss this brilliant human being. It is with great sorrow to see his passing. It’s not often someone of his motivation and brilliance walks this planet. He will be missed by many. May he rest in peace.
Thanks to the ceramic engineers at 3M we now have a material, zirconia, strong enough for most applications. The origin of this market began with Lava, a CAD CAM fabricated framework material with very limited inductions and a very steep cost of entry.
Many lab owners paid in the $250K range to bring manufacturing in-house. Although very successful, Lava did have several challenges. The CAD design was antiquated and posed many problems to designing proper frame design. The mill, being 4 axis, also limited manufacturing of some geometries. The block’s initial form enabled only single units, followed by larger blocks that eventually enabled eight unit cases. There were additional problems with baking ceramics to zirconia that have been well documented. Chipping and delimitation were all too common. More recently, through developments made at Glidewell laboratories, full contour zirconia has become increasingly popular. In part, this is due to dependability, as there are no layered ceramics and thus no chipping or delimitation.
Full contour monolithic comes with low cost of manufacturing, continued esthetic improvements and increased indications. The original Bruxzir material from Glidewell was milled from a 98mm disk, which enabled any size restoration.
The disk was white, resulting in the need to dip the milled restoration into coloring liquids before sintering. More recently many companies have added colorants to the disk to eliminate the dipping process. This has proven to be a more consistent manufacturing process with fewer shade problems, but the restorations are very monochromatic and more opaque than natural dentition.
Today, developments include several new disks that have multiple shades pressed into each disk. For instance, CAP Multi FZ has a cervical, body and enamel shade with a blended zone between each layer. As the latest advancement we now have a monolithic multi-shaded material that more closely resembles natural dentition. Priced similar to other quality disks, the esthetic barrier of zirconia is rapidly becoming a thing of the past.
In the not too distant future we will have zirconia materials that will be far more translucent. Expected by year end, the new class of zirconia materials will likely become the go-to product for many dentists. This newest class zirconia material will not be as strong as the materials of today (1100 MPa) but offer a 50% increase in strength (at 600 MPa) over lithium disilicate (360-400 MPa). It is anticipated this new super high translucent material will be available in pre shaded discs for predictability and ease of use.
It’s truly amazing how far we have moved the needle on zirconia in such a short time.
For more info on CAP Multi FZ please visit: http://cap-us.com/products/cap-multi-fz-fz-2/
Thanks for reading.
Bob Cohen, CDT
I was in Germany for technology preview with a few companies last week. I was introduced to some great new products. I will likely write a few blogs in the coming weeks about much of what I saw there. So keep following the new blogs over the next few weeks for more on what’s new for innovative digital technologies in our industry.
An interesting development, the Priticrown, by Pritidenta of Germany, has been introduced in Europe and is currently coming to the US market. The Priticrown is a new milling block for single units that is near net shape, multi layered ceramic milling blank.
When looking at these near net shaped blocks it’s immediately easy to see the block comes in the shape of the tooth you need to restore. As a result, when milling, there is a significant time savings as you no longer need all the grinding to get the rough shape required for final contour. This not only saves mill time, it also reduces tool wear and related cost of each. It’s my understanding, it reduces mill time by about 30%.
The material used for Priticrown preforms is a layered Vita Mark II. This particular ceramic has over 20M units in the mouth with documented long term studies that indicate greater than 95% success rate after ten years. The material utilizes an etch and bonding procedure for best results. Each preform is uniquely layered with a body and enamel shades for optimal esthetics. In fact, Priticrown is likely the most esthetic milling material available. Making it a best in class choice for automated anterior restorations.
The workflow is really quite simple; scan, CAD, and mill. For CAD one can use either 3Shape, Exocad or Dental Wings, as each company now has the preform libraries in the related software. When designing, there are a couple of small changes needed to insure the design fits inside the block. The ceramic material is easily ground on and can be polished or glazed. Polishing can be easily achieved using most porcelain polishing systems and provides a lifelike final luster.
Left: Priticrown pre-form milling blank
Center: Milled Priticrown
Right: Final crown, polished and ready for insertion
Thanks for reading,
Bob Cohen, CDT
For nearly thirty years the conventional screw retained denture or hybrid has been the standard of care for many dentists and patients. In many practices this is still a treatment of choice for converting denture patients to fixed implant supported restorations. In the mid 1980′s Dr George Zarb developed this full arch screw retained prosthesis that, for the times, was a great innovation that provided tens (if not hundreds) of thousands of patients fixed restorations to replace dentures. In the 1980′s this was state of the art for fixed implant supported restorations.
This hybrid restoration is fabricated with conventional denture teeth, processed to a cast or milled metal bar using denture base material. The prosthesis is subsequently a screw retainer to the implants or interim abutments facilitating a fixed prosthesis. This was an amazing upgrade for denture patients. Eliminating dentures and the pallet, reintroducing the concept of taste and having a fixed restoration can be life changing. However, the hybrid restoration has not been adequately predictable or trouble free. Many patients experience prosthetic failure, breakage of the acrylic and/or teeth coming loose from the restoration. Often this can happen in less than a year or a month or less, after receiving a new hybrid prosthesis.
Through material and functional analysis it becomes obvious why the hybrid restorations are so problematic. Denture teeth and denture base materials were developed for dentures. Dentures tend to be loose fitting. Patients applying excessive lateral loads to conventional dentures will simply dislodge the appliance. Through initial and continued function with dentures, patients adapt to denture functionality and learn quickly not to exceed functional limits. The functional load limits placed on a denture are well within the strength of denture materials, being 80-100 MPa flexural strength.
When utilizing the same denture materials to a screw retained prosthesis the element of dislodging the appliance is removed form the equation. Patients can easily place loads of over 400 MPa on fixed restorations, hence the problem of under engineering is evident. In addition, implant patients lose proprioception, resulting in the inability to gently guide or control functional movements, resulting in frequent high load unpredictable maxillary and mandibular tooth collision.
Through the advent of material science and CAD CAM we finally have a solution, Izir and Pretau bridges. These restorations are fabricated from full contour zirconia. Having a flexural strength of 1100 MPa the material far exceeds loads placed on screw retained restoration. The Izir restoration follows a protocol that is predictable and cost effective. Due to strength, it is built to withstand long term function and provide years of trouble free use. In addition, digital manufacturing of this restoration means we own the design file forever. In the event of an unforeseen problem, a remake is as simple as pulling up the original design file and milling a new prosthesis. Just a single appointment is needed to screw out the old and place an all new Izir. This is insuring for both the patient and restorative dentist.
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For decades laboratory technicians have fabricated diagnostic wax-ups as treatment planning aids when providing services for comprehensive dentistry. This diagnostic wax-up had multiple uses. First, it enables working out esthetic and function needs on an adjustable articulator. By doing so, many of the treatment plan perameters become obvious. This reduces potential problems with the final restoration. Secondly, the wax up can be used as a tool to show the patient what their final case would look like. In addition, a silicon matrix can easily be fabricated over the wax-up and used to facilitate provision fabrication and an intraoral mock up. This mock can be effectively done on about 50% of cases. In case you’re not familiar with a mock up here is the protocol:
Diagnostic wax up is performed and a silicone matrix is fabricated over the wax up.
Through the more recent advancements in CAD CAM a new, much more accurate, predictable workflow is now available for comprehensive cases. This does not necessarily replace a diagnostic wax up, but in many cases, it can. It involves milling of a CVB prior to fabrication of the definitive restoration. The protocol includes an intraoral try-in of a final case design prior to fabrication of the definitive restoration. By doing so, one can check intraorally all the essential design elements and parameters. A CVB is a milled PMMA (polymethyl methacrylate) try-in bridge. The CVB is essentially a milled acrylic bridge that is milled from a CAD design intended to be used for the final restoration. Once the try-in is performed and evaluated, the original CVB design can be brought back to the CAD stage and altered or tweaked as needed to insure predictability and accuracy of the final restoration. Here is how it works:
The utilization of a CVB will provide a far more predictable result. In addition, the quality of the final prosthesis will be more favorable to both the dentist and patient. Lastly, through the fabrication of a CVB first, clinical appointment objectives are much more likely to be accomplished on a more routine basis.
Do you find bites to be more of a problem with implant cases than traditional crown and bridge? We sure do! This is due to a few factors. First, when taking a bite registration that utilizes the soft tissue or ridge as a stop, the inaccuracy can be quite large. This is caused by compression of the ridge during the impression procedure. This can displace the tissue by a millimeter or more. As a result, subsequent bite registrations do not fit the casts adequately.
In comparison, when taking a crown and bridge bite registration the registration and mounting is performed with bite material placed between the opposing teeth and the tooth preps. NO SOFT TISSUE CONTACT. As a result, the problems of proper vertical are reduced.
A friend of mine, Dene LeBeau, has developed the Implant Bite Post (IBP). The IBP is available in a long and short version and is compatible with many of the most common implant interfaces. This small but insightful innovation has dramatically reduced the problem of obtaining proper vertical for implant supported restorations. In addition, the IBP reduces the need to fabricate base plates and bite rims that require patients to return for an additional appointment just to obtain a bite registration (that is likely not as accurate). The bite procedure can routinely be accomplished on the same visit as the final impression. As a result of all the many advantages of the IBP, CAP now has a complete inventory of Implant Bite Posts for anyone looking to solve the common problems of bite registrations on implants.
You can see both maxillary and mandibular implants have been placed and there is no way to articulate this cases by hand.
We have finalized the workflow and related component libraries to include the Multi-unit Abutment for Izir restorations. This advancement enables Noble Biocare workflows and parts for Izir production