Posterior indirect photographic documentation

Esthetics in dentistry comes in many forms. Porcelain veneers, composite bonding, porcelain crowns, teeth whitening, orthodontics: all of these are powerful tools to use when treating esthetic cases for our dental patients. However, it seems like the emphasis for esthetic dental restorations is generally related to the patients’ front teeth. 

What about the premolars and molars? I feel strongly that, whenever possible, esthetic dentistry should be provided regardless of the tooth position in the patient’s mouth – front tooth, side tooth, back tooth. My opinion is based on two points: 1) the materials available today allow us, in most circumstances, to create naturally appearing restorations, and 2) my experience that patients judge us on dentistry on back teeth, before they trust us to do dentistry on their front teeth. As crazy as it might sound, I have had several patients that come to me from their general dentist to do cosmetic dentistry, because, as they framed it, “if the dentist couldn’t make my back teeth look nice, how can I trust them to make the front teeth look good?”. It might be as simple as an occlusal composite or a ceramic crown, but many patients will judge us on dentistry outside of what we normally think of as the ‘esthetic zone’ – our basic and routine restorative dentistry.

Many years ago I was frustrated that the crowns that I was receiving back from my lab lacked natural characterization and did not blend with the patient’s natural teeth. I was speaking with Don Cornell, a master ceramist from Newport Beach, California, about my disappointment with these posterior crowns. Don asked me a very simple and profound question that I still think about today – he asked, “Are you taking pictures of the patient’s neighboring teeth and sending them to my lab technician to use when building the crowns?” It absolutely never occurred to me to use photographs to help my ceramist fabricate crowns for teeth other than the patient’s anterior teeth. After that conversation with Don, I immediately began taking photographs of the neighboring teeth even when restoring a lower molar with an indirect restoration. What a difference it made!

The problem that we experience is that the shade of the teeth does not exactly match the color (hue, chroma, value) of the shade guide tab(s) that we are using to communicate shade to our technicians. So when we tell our technicians that the tooth is Vita Shade A1, and the technician fabricates a crown that looks like Shade A1, it rarely blends in with the natural dentition. This is because, as we all know, teeth are highly complex when considering translucency, colorization, and surface effects. Photographs of the shade guide adjacent to the teeth that we are documenting give the technicians valuable information that will allow them to enhance the ceramic restoration to better blend with the natural teeth. When I take a photograph of teeth using, for instance in this case, the Vita shade A1 and A2, the ceramist can note that the value of the teeth are a little lower than the shade tabs in the photograph, and probably need a little more chroma. 

Technicians will also appreciate the increase in chroma, how far into the body of the tooth the chroma intensifies. Subtleties, like craze lines, facets, stains, and surface texture can be added to the restorations to create as life-like restoration as possible. Using a polarizing filter will also give the ceramist valuable information related to the value, or brightness, of the tooth to be restored. The polarizing filter works by eliminating the reflection from the light and flash to help gain a true appreciation of the chroma and brightness of the teeth in the photograph, relative to the accompanying shade tab(s).

The following are my recommendations when photographing posterior teeth for indirect restorations:

1. Use a 35 mm digital SLR camera with a 100 macro lens. I use a Canon 5-D, but there are many cameras available for dental applications.

8. We take multiple photographs with different combinations of shade tabs. Typically we will have one shade tab at the incisal/cusp tips of the bicuspids, and a more chromatic shade tab at the gingival 

9. Make sure that the shade tab number is visible. Don’t zoom in too closely that you only see the shade tab, but you aren’t able to see which shade it is. Also, make sure that the person holding the shade tab does not have their finger or thumb covering the shade number.

10. Very often if the shade tab angle is parallel to the camera lens, the light from the flash will reflect or bounce off of the metal holder of the shade tab. This causes too much light to hit the sensor. The result is that the image will be black or too dark to be useful for the lab technician. So very often, the camera or the shade tabs need to be re-angled so that the light reflection does not cause the over illumination of the sensor. Be prepared to change the angle of the camera or have your assistant reposition the shade tabs.

11. Use a polarizing filter (I use the Polar-Eyes) with the same shade tabs. This will help your technician when evaluating the value of the restoration. You will either need to increase the light output from your flash, or open the f-stop to allow more light into the sensor with the filter over the lens.

12. Following preparation of the tooth, we’ll take both occlusal and buccal photographs using retractors (typically metal retractors) and buccal mirrors. These images are critical for the ceramist to see the underlying color of the tooth to understand the opacity of the porcelain necessary to either allow the natural tooth color to shine through or to block darkness that would affect the overall value of the ceramic restoration.

13. The images are transferred from the memory card to our computers. Finally, the images are transferred to the lab technician for use when they fabricate the onlay or the crown.

These photographs are typically done by my dental assistants, but it is important that the dentist is also an expert in these photography techniques. In my 20 years of dental education experience, if dentists are not comfortable taking photographs, it is impossible for them to train their team members to take excellent photographs. If you think that your team is not skilled enough to be able to take photographs, think about how difficult it is to take intraoral x-rays. I believe if someone is skilled enough to take really good x-rays, they can be trained to take excellent dental photographs. 

Yours for better dentistry,