There are many ways to gain retraction today for final impressions. With all those options I still find that a two cord technique creates the most predictability in my hands. One of the challenges with a double cord technique is the removal of the top cord when there are multiple preps to impress at once. A technique I learned many years ago of using a continuous top cord makes this step much simpler. This technique is designed to be used with veneer preps, and can not be used if the preparations include the lingual surface of the tooth.
I have spent the last two days at the ADA Annual Session teaching on topics from occlusion to provisionals. One conversation kept coming up over and over, so I thought it is a perfect topic for a post. I was amazed at how many times I found myself discussing using a brownie, silicone polishing point, in a high-speed handpiece in my office. So first, as a caveat, you can not run a brownie point at full speed in a high-speed handpiece, it will turn into a silicone grenade. I work with electric handpieces, so I dial them down to half speed. If you are using air driven, simply press lightly on the rheostat so you do not get full power.
A large majority of the anterior restorations I complete incorporate changes to tooth position, alignment or contour. I aim to balance the required tooth reduction to accomplish the clinical goals with being conservative. Often the changes we are making between the existing tooth position and the proposed tooth position are additive and act to reduce the amount of reduction required. Tooth reduction is challenging enough to get accurate without the added guessing of what will be needed to accomplish the tooth form from a wax-up. Transferring the information from the diagnostic wax-up to the teeth in the form of a mock-up allows me to use my usual technique, cut depth cuts and create the required reduction from the final tooth position, conserving tooth structure.
Alginate impressions are one of the main stays in a general dental practice. Think about all of the clinical procedures that we do whose success depends on an accurate alginate impression, from diagnostic planning on models to the fit of removable prostheses and more. In the face of the important role that alginate plays it is also one of the most overlooked and under trained technique we do. This week in my office we have had the opportunity to take a large number of alginate impressions and the conversation about how to take them and what the expectations are for success.
In a prior post I mentioned that the incidence of pulpal death following an indirect restorative procedure is approximately 13%. This number goes up to near 18% if the same tooth also had a buildup done as part of the process. The research is clear that the largest insult to the pulpal tissue is bacteria. Whether from caries, introduced into the tubules during preparation, or present from a leaking temporary restoration. Well fitting provisional margins are our best defense against leakage.
A common question I get is what the best material is to restore discolored teeth. We have an enormous number of really great materials available today for both veneers and full coverage restorations. They each have different color and light reflection qualities, and a different ability to mask underlying tooth discoloration. With all of that said the first thing to look at is what I call the” two shade” rule. When we think about using indirect restorations to alter tooth shade, lightening two shades on a Vita Classic shade guide requires nothing outside our standard procedures. So when we go two shades lighter or less then the starting shade, we can choose from any of the current materials and get exquisite results, and create our usual prep designs.
With the minimum reduction numbers in mind for your occlusal reduction the next step is preparing the tooth. There are two critical steps during preparation that predictably create adequate reduction, knowing the dimension of the burs that you are using and beginning with depth cuts to create a visual reference once the prep is underway. There are many different burs, both diamonds and carbides that will work to create depth cuts with adequate occlusal reduction. Find something that works for you, in your hands, but chose the bur with intention and have a consistent system for how you use it.
One of the things that helps grow my practice more then any other, is the lengths I go to making sure it is as comfortable as possible when I give anesthesia. Whether patients are anxious about getting the “shot” or not, not one looks forward to it. and all of us brace ourselves in anticipation. Over the years I have continued to refine my anesthetic technique, because over and over patients comment on how surprised and pleased they are by how comfortable it is. When new patients arrive in our office on a referral, we hear over and over that their friends couldn’t believe how little our shots hurt, and how much effort we went to making them comfortable.
One of the daily challenges in my practice is assuring that I have created adequate tooth reduction and at the same time not taking away more tooth structure then necessary. Occlusal reduction is a common place that I realize I have under reduced when fabricating the provisional or worse yet when the lab calls or sends the restoration back thin. There are many ways to ensure I have created the right amount of reduction, but before i can do this, I need a goal in mind, so how much space to I need to create.
Having adequate occlusal reduction creates predictability of the final restoration, both esthetically and structurally. I decided to go to the literature and do some research. If we look at success rates of all porcelain restorations in the posterior relative to occlusal reduction, the evidence is clear. Inadequate reduction increases the risk of fracture and failure of the restoration prematurely when placing all porcelain restorations. Due to the inherent physical properties of the porcelain, there are minimal thicknesses for success, and we need to prepare teeth to meet these parameters.
There are things in practice that can make my day, or set it on end. The occlusal adjustment required when seating final restorations is one of these things. I absolutely love it when the restoration goes to place and needs almost no adjustment to the occlusion. On the other hand when I am trying in the restoration and ask the patient to first close, and can instantly tell it needs a large amount of adjustment, my attitude changes and frustration is the word of the day. Over the years I have worked towards predictably eliminating these frustrating situations and knowing that the majority of the time the occlusion will be extremely close at try-in. There are a lot of pieces to this puzzle, but a key is how the information about the occlusion is sent to the lab.