Before the advent of pressing technology ceramic restorations were most commonly produced using a process of combining liquid and powder into a slurry and then stacking this porcelain on the die. The ceramic is applied this way in layers and then fired. This process is still commonly used today and understanding the properties can allow us to use it to our advantage to achieve the clinical results we are after. Ceramics fabricated in this way are typically feldspathic or leucite reinforced glass, and used primarily for anterior restorations. The fabrication process is challenging and time consuming and requires a skilled ceramist to create both the esthetic results and a precisely fitting restoration. An advantage of this type of ceramic restoration is the ability the technician has to layer material of varying color and opacity.
The final esthetics of an anterior all porcelain restoration that does not contain an opaque core, is the result of the color and light properties of the tooth combined with the restoration. Because of this a critical piece of esthetic information for the lab is the stump shade and a stump shade photograph. Different technicians have preferences about taking a stump shade. There are special shade guides that you can purchase for taking a stump shade. One of the most common is the Natural Die Material Shade Guide from Ivoclar. The shade nomenclature uses ND and then a number from one to nine. One of the advantages of this system is the technician can actually fabricate the die from the stone that matches the stump shade you chose.
Almost a year ago in a post I shared my experience using the EasyShade from Vita in the office to gather shade information. My personal experience with it has been nothing but positive ever since. I am asked often about whether it works, is it w worthy investment and I can share that I would not want to be without it in my office, but that is not very scientific. Today at the Society for Color and Appearance in Dentistry meeting in Chicago shade technology was covered from the podium. In a study by Lehman et al in 2002 they looked at the accuracy of visual shade determination versus shade technology. The overall results were that the technology was accurate 98 percent of the time, compared to visual determination being accurate only 70% of the time.
This video is an excerpt from the first session of our current online seminar “Techniques & Materials For Exquisite Esthetics” . In this segment I talk about collaborating with your dental ceramist early in case treatment planning to create predictability and exquisite outcomes.
Online seminars are available live and as recordings. If you are interested in access to the full content please use the above link and follow the prompts for registration.
Recently when presenting in Minneapolis at the Star of The North a conversation came up about managing a single dark tooth during the restorative process. If the tooth has had endodontic therapy one approach is internal bleaching to lighten the stump shade. Often though these teeth have not been treated endodontically, and there is some evidence of increased risk of internal resorption following internal or walking bleach. A friend and excellent dentist that I know joined the conversation and shared a fantastic tip. He explained that if the tooth is treatment planned for a full coverage restoration he uses the provisional as a bleaching tray. Since then I have used this technique numerous times with great success.
Having to remake dentistry is a fact of life. The more important question is what is the percentage of time you have remakes? First let’s start by defining what I mean by a remake. These are restorations that have to be altered or re-made prior to being permanently seated. This is a different conversation then having to replace restorations after they have spent time in the mouth.
My remakes occur for reasons like marginal discrepancy, inability to seat the restoration, open contacts, excessive occlusal adjustment and poor color match. I began wondering about this when I heard a recent statistic that the average dentist who works with Glidewell has a 6% remake rate.
Matching the surface morphology of an anterior tooth is a critical component in achieving exquisite esthetics. It doesn’t matter if we are restoring the tooth with composite, porcelain or simply sculpting a provisional. One of the challenges in being able to match the surface morphology to create symmetry on either side of the midline is how we document it. This weekend I learned a very neat way to see the existing surface morphology of the teeth or of my restorations during a lecture by Dr. Brian LeSage at the Heraeus 4th Annual Symposium. If you have ever played the game as a kid where you uncover what was written on the previous piece of paper by using a lead pencil, then this will be a cinch. With a pencil and a piece of paper you simply use the side of the lead to color the paper, and it leaves the depressions in the paper from the previous page white so now you can read them.
I learned a very interesting statistic today: 68% of the time when a dentist switches laboratories it is because of inconsistent clinical results from their current lab. When I heard this, I wasn’t surprised as consistent, accurate clinical results are a must. We all need to know when we sit down to seat a restoration that the process will be predictable and the finished product excellent. A single forty-minute episode of adjusting in the occlusion on a crown ruins not just that day, but also the whole week. What I wondered about was the process that led to the dentist switching labs. Working with a new lab can be nerve-racking. It takes time to build confidence and get comfortable with the systems around simply sending work in and getting it back.
I utilize stick bites very often in my practice, as an additional piece of information for the lab. Along with my facebow transfer, bite records, and photos the stick bite is sent to the lab for both wax-ups and fabrication of the final restorations. The stick bite serves several functions. First it references the incisal edge to the horizon. This is a key piece of information for the technician, They can now create the final incisal edge position and know that it is level to the horizon, and how it relates to the rest of the occlusal plane and the patients eyes and face.
As an adjunct to our lab communication I have found it incredibly helpful to employ shade technology. I use the Easyshade Advanced by Vita. What the technology allows me to do is narrow the field of chroma and hue choices down, before I reach for a shade guide. It also allows everyone in my office to feel equally capable at getting the basic shade information. In years past taking a shade was challenging, team members were hesitant to participate for fear of getting it incorrect. The technology has taken that apprehension out of the process, and they are happy to get the initial reading.