“How translucent is that zirconia?”
This is a question I often hear when walking past dentists at a trade show booth for a new millable material. I tend to find we try to oversimplify esthetics into one parameter, and often we fall short on achieving the esthetic outcome we want for our patients. Milled monolithic materials can do an excellent job mimicking the anterior dentition; however, we must take a much deeper dive into what makes an esthetic milled restoration.
Defining esthetics is a difficult task that is not black and white. To simply put it, esthetics is a branch of philosophy dealing with the nature of beauty, art, and taste and with the creation and appreciation of beauty.1 Cultural perceptions, personal preference, and professional experience all play into how we determine what is esthetic for our individual patient. In this article, I will walk you through the two acronyms I use to help guide me through treatment planning and successful execution of anterior esthetic chairside milled restorations.
The 3 R’s and the 3 C’s:
As an officer in the United States Army, we learn that to have a successful outcome we have to identify the “center of gravity,” or source of power of an objective, to successfully complete a mission. I view esthetic dentistry no differently. We must be able to record the condition we wish to fix, recognize the key components that need to be corrected, and replicate the surrounding dentition if we want to have a successful outcome. The Triple R protocol was first described by El-Etreby in 2018, and we can expound on this concept to look at it from a holistic treatment planning principle.
Recording the condition is critical to your overall success. Clinical photography must be a routine part of your anterior CAD/CAM restorations, and although there are software solutions and companies that automate this process for you, it comes at a monetary cost.
Recording the dentition does not require equipment that is overly expensive or time consuming to learn. The clinical photography set up that I personally use is under $850, and photographic management programs such as PowerPoint or Keynote can be used to annotate esthetic deficiencies that you see, even if you do not yet know how to correct them.
Recognize: Consistency, Contour, and Color
Being able to recognize what esthetic conditions need to be corrected takes time. In the 2002 publication by Magne and Belser, they describe 13 principles to having a balanced and harmonious anterior dentition. To simplify these 13 principles for the purposes of this publication, I will break it down into three principles: contour, consistency, and color.
Contour refers to the large proportional shapes of the tooth. For this, I look at basic proportions of length to width, arch length, and overall tooth shape. I use PowerPoint to aid in my communication to my staff, lab, and patients by simply uploading my photos and using the picture format tool to calculate a length to width profile, and using pre-drawn templates to identify teeth that are not harmonious with the dental arch.
Sometimes clinical photographs can play tricks on your eyes, especially when you are dealing with tooth consistency. Consistency is the surface texture of a tooth, and it is the difference between an “ordinary” CAD/CAM restoration and an “extraordinary” CAD/CAM restoration. To record and replicate consistency, I use articulating paper to drag across the facial surface of the teeth I am trying to replicate to identify vertical and horizontal lines. From there, I develop a topographical map on how I later plan to replicate the surrounding dentition.
Finally, there is color. Color is the first parameter I record, but the last consideration I have prior to milling a restoration. Color is complex and involves understanding of hue (the physical wavelength of light), chroma (the intensity of a color), and value (the degree of lightness and darkness). Beyond that, we must also understand that fluorescence (ability of a material to emit a certain wavelength) and ceramic particle size affect a material’s ability to reflect and absorb certain wavelengths of light resulting in a phenomenon known as opalescence. Feldspathic ceramics often have the best esthetic principles to mimic the natural dentition in terms of fluorescence and opalescence, but they may not have the best physical characteristics in a worn dentition. So, although principles of translucency and opalescence may be important, we can replicate these characteristics using additive staining to mimic a “transmitted” color.
Replicate: Biology and Engineering
Replicating what you have recorded and recognized takes practice, patience, and a little bit of luck. When I think about replicating the dentition, I think about both the biology and engineering to have a successful outcome. To mimic biological characteristics in the tooth, I try to use additive staining in a CAD/CAM monolithic crown. For translucency, I use blue/grey on incisal edges, and for an opal effect, I will use an orange stain. Some materials such as feldspathic porcelains and advanced lithium silicates have a small enough grain size to give an opal effect. As a general rule of thumb, it is safe to say that if it is not a feldspathic block such as Vita Mark II, Empress (leucite reinforced), or Celtra Duo (advanced lithium silicate), you will have to contend with placing reflective stains to mimic your opal effect.
What about just getting a more translucent block instead of staining? Too much translucency on a milled restoration is often a bad thing. On a natural tooth, we have gradients of translucency, and too much translucency in the gingival and middle third can lead to a “graying” out of your restoration. For single anterior teeth, I tend to gravitate towards a “MT” or a medium translucency block, or a poly block that has multiple gradients of chroma and translucency.
Engineering is how we prepare the tooth for an anterior esthetic situation. If we understand that our CAD/CAM materials will transmit color, we also have to manage our Stumpf shade. In a 2021 article by Durães, he described the thickness of lithium disilicate needing to be 1.2mm of LT to have the best esthetic management of a dark substrate. In this study, a LT (low translucency) block provided the best masking of the Stumpf shade, which in an anterior situation may not always be ideal. Furthermore, to manage a dark Stumpf shade you can use a direct opaquing resin (Clearfil ST Opaquer by Kuraray) as part of your immediate dentin sealing technique prior to scanning or use a cement system that can vary the chroma of the dentin show through (Variolink Esthetic by Ivoclar Vivodent).
I wish there was a material, a method, or stain that did it all and could predictably deliver anterior esthetics directly out of a milling machine. The fact is that there is no perfect material, and no “silver bullet” to anterior esthetics. After reading this article, I hope that you can start to see there is more to anterior milled esthetics than “how translucent” a block is. By starting to systematically approach every tooth with the 3 R’s (Record, Recognize, and Replicate) and focusing on the 3 C’s (Contour, Consistency, and Color), you will be able to see steady improvement in your anterior chairside milled restorations. Start on the molars that you mill and apply the same principles. Spend your time shaping and staining your posterior restorations, and one day you will surprise yourself with some extraordinary anterior outcomes!
- Merrian Webster dictionary.
- EL-Etreby, A. S. (2018). Intraoral characterization of monolithic ceramics: The “Triple R” protocol. Future Dental Journal, 4(2), 268-273.
- Magne, P., & Belser, U. (2002). Bonded porcelain restorations in the anterior dentition: a biomimetic approach. Quintessence Publishing (IL).
- Durães, I., Cavalcanti, A., & Mathias, P. (2021).
The Thickness and Opacity of Aesthetic Materials Influence the Restoration of Discolored Teeth. Operative Dentistry, 46(5), 559-565.
- Ivoclar Vivadent, A. G. (2009). Technical notes: IPS e. max CAD, instructions for use.