Oral Health Group
Feature

Lab Communication Utilizing Digital Photography

July 1, 2006
by Tony Soileau, DDS


Lab communication is essential to the success of any restorative case. It does not matter if it is a simple single unit posterior crown, a cosmetic veneer case, or a very complex full mouth reconstruction. If the ceramist does not fully understand the expectations of both the patient and dentist the case can turn towards failure. In the past, the dentist communicated with the ceramist with crude drawings on diagrams or 35mm slide film photography.

A drawing of the shade locations on a tooth diagram does communicate a certain amount of information to the ceramist. But it leaves a lot to interpretation by the ceramist. The color, texture, and shape of the surrounding teeth must be guessed at by the ceramist. The use of 35mm slide film or even print film photography was an improvement in lab communication. Film or slides taken of the shade tab next to the tooth allowed the ceramist to utilize information about the case that was not available with drawings. The downside to using print or slide film is its inefficiency and advanced photographic knowledge needed by the dental team. If a 36 exposure role of slide film is used but only a few photographs are needed then both film and money has been wasted. The film must then be processed outside the office by another company. Print and slide film cameras were also not that easy to operate without a great deal of photographic knowledge.

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Digital photography has greatly simplified and expanded lab communication. In the article I will discuss the advantages of digital photography and some factors to be considered in purchasing digital cameras and accessories for lab communication.

There are two types of digital cameras to consider for lab communication; point and shoot style cameras and SLR (singe lens reflex similar to 35mm style cameras). Point and shoot style cameras have the advantage of being very light and inexpensive compared to SLR style cameras. Team members appreciate the small size and weight. But the small size comes at the expense of quality and ease of use. Most point and shoot cameras have a fixed lens. These lenses have a short aperture range or a small range of f-stops. The higher an f-stop a lens has the greater depth of field it can capture. Another way of saying this is the higher the f-stop number such as an f-stop of 22 or 32 the more of the image will be in focus. I use an f-stop of 22 for all my clinical photos except for a full face image. I use 6.3 for a full face image. Most point and shoot cameras have a maximum f-stop of 8 or 11. This means your smile and retracted smile shots will have the molars out of focus. With a SLR style camera such as the Canon 20D an f-stop up to 32 can be used. This means every part of the image will be in focus.

Flash systems with digital cameras are another consideration to be made when purchasing a digital photography system. The most common flash system for clinical digital photography is a ring flash. A ring flash is designed to illuminate an image that is taken very close up. It focuses the light in a narrow range that makes taking intra oral shots very easy. The light from a ring flash comes from all directions. This is opposed to the on board flash found on point and shoot style cameras. The single flash leads to increased shadows on one side of an image. The on board flash is also very weak compared to a ring flash. This means you have to be very close to take an image of a shade tab. Capturing an image this close to a patient’s teeth can often time over expose parts of the image that is needed by the ceramist. Another type of flash system to consider is a twin flash. A twin flash has two flash strobes that can be repositioned at a multitude of positions.

One disadvantage of a ring flash is that it does its job too well. It illuminates the entire field from all directions. It essentially eliminates all shadows. The problem with removing all shadows is that it also removes the texture of the teeth. This causes the teeth to have a flat appearance. A twin flash sends the light from two directions so the image is properly illuminated but the very slight texture of the teeth is still visible. The problem with a twin flash however is that the flash strobes are positioned so far apart that the flash bounces off the cheeks for some intra oral images. This is especially true if the patient has a small mouth.

Another consideration is which lens to purchase for your digital camera. The most common lens is a 100mm Macro lens. This lens is designed to take images at a very close range. However it can also be used to take very dramatic portrait images as well. A 60mm Macro lens has become popular as well.

The difference in the two lenses will be cost, weight, and focal length. A 60mm Macro lens will be slightly cheaper. It will also weigh quite a bit less than a 100mm Macro lens. The lens is what weighs the most with a digital camera setup. The focal length of the two lenses is where the 100mm Macro lens has an advantage. The same image taken at 12 inches from the teeth with a 100mm Macro lens will have to be taken at 6-7 inches with a 60mm Macro lens. Taking an image 6-7 inches from a patient’s face with a ring flash can be uncomfortable for the patient. The flash is very bright at this distance. For this reason I prefer the 100mm Macro lens.

There are several methods for sending images to the laboratory. One method is to print the images and send the print to the lab. This method gives the dentist control over the quality of the image the ceramist is using to create the restorations. The downside to printing the images is the printer’s inability to produce all the entire range of colors found in the image and the need for the dentist to maintain a supply of ink and paper.

Another method is email the images to the laboratory. This method is convenient but forces the dentist to reduce the size of the images for emailing which in turn reduces the quality of the images. A third option is to burn the images to a disk and send the disk with the case to the laboratory. This is the method I use with my ceramist. The laboratory is then obligated to view the images with a quality monitor that is calibrated correctly.

Using digital photography for lab communication is simple and easy. The latest digital cameras take images at a quality that surpasses film. The camera functions can be automated to a point where a novice photographer can take perfect images with very little effort. Because the images are saved on a compact flash card instead of film a dentist can take as few or as many images he wants without wasting film. These advantages make digital photography an incredibly efficient, predictable, and affordable

Dr. Soileau is a general dentist from Lafayette, Louisiana. His practice focuses on restorative rehabilitation and cosmetic enhancements. He lectures nationally and internationally on the use of digital photography and computer assistance for diagnosing, treatment planning, and performing comprehensive dental procedures. He is a consultant for several technologies based dental manufacturers and beta tests many of their products. He has also received Fellowship Status in the Academy of Comprehensive Esthetics.

Oral Health welcomes this original article.