Del DSD Al PSD - 2006 Por McLaren

8/10/2019 Del DSD Al PSD - 2006 Por McLaren

1/4


2/4

INSIDE DENTISTRY OCTOBER 2006

sends out small bursts of light andmeasures what reflects off of the sceneand hits the camera sensor. It is theauthors opinion that the spot meter set-ting is best for dental photography.When a scene is spot metered, the cam-era is only metering the area within thesmall spot seen in the viewfinder andthe exposure is based on this readingonly. The spot meter (the small circleseen in the view finder) should beplaced only over the area you wantexposed correctly (Figure 3). In the caseof close-up dental photography, thatarea is the teeth. It is important tounderstand that that camera will exposethe scene to an exposure of what an 18%reflective gray card would look like tothe eye. Scenes that are very white willbe underexposed slightly by the camerato gray it out a little (ie, very white teethwill expose a little darker than perceivedvisually). Scenes that are very dark willbe overexposed to make them appearbrighter (eg, dark teeth will be exposedbrighter than would have been perceivedvisually). The benefit in shooting in aRAW file format mode is the exposurecan be reset easily to what was visually perceived. There are many advancedphotographic, camera, and computerfunctions that could be used to exactly control for this, but the nonprofessionaluser will find it too tedious and timeconsuming to do. Shooting in RAW,metering the scene in spot correctly,correcting the f-stop, and shooting inAP will give excellent results easily.

FLASH SELECTION AND USEThe proper illumination of a scene is themost critical factor in any kind of pho-tography. Flash selection and properplacement are actually more importantthan camera body selection. Electronicflashes are required for close-up (macro)dental photography. Ring lights or pointflashes (Figure 4) have been used for along time for this purpose; however,ring lights tend to flood the scene withlight, giving a flat image. The surfacetexture and translucency also is not wellvisualized with this type of flash. Theauthors prefer a dual-flash system thatallows some custom positioning of theflash. For the Canon system, the authorsprefer the Macro Twin Lite MT-24EX flash (Canon USA, Inc) (shown in Figure

1) and the recently released R1C1 Wire-less Close-Up Speedlight System flash

Figure 5 This image,taken with a ring flash,clearly demonstrates the harsh unflattering lookwith this type of light.

Figure 7 The minimum studio set-ustudio strobe light with a soft box andrate reflector.

Figure 8 The camera body with an on-cameraflash with the Lightsphere II Diffuser attached.

Figure 6 An image taken with specialized soft-er light. The image is much more flattering.

Figure 9 The set up and taking an image with the Lightsphere II Diffuser.

Figure 10 An image using the Lightsphere II

Diffuser.The image is almost as good as with thestudio strobes.

Figure 11 Image of a full-face M position,

which demonstrates incisal display at rest.

Figure 12 Image of a full-face smil

demonstrates the incisal and gingival dduring smiling.

Figure 13 Image of the lower third of the facesmiling at 1:2 magnification.

Figure 14 Image of the lower third of the facewith the cheeks retracted taken at 1:2 magnification.

Figure 15 Close-up image of the anterior teeth taken at 1:1 magnification.

Figure 16 The dental contrastor from


3/4

(Nikon, Inc) for the Nikon camera (shownin Figure 2).

LIGHTING FOR FULLFACE AND ESTHETICPORTRAIT SHOTSCamera flashes, including the dual pointand ring flash, give a very harsh and un-flattering illumination of the subject(Figure 5). This type of flash is accept-able for preoperatory full-face images, butis not desirable to show postoperativeesthetic results.Softer lighting (large anddiffuse) is much more ideal for postop-erative full faces and portraits (Figure 6).If you have the space and the desire forprofessional-looking portraits, a mini-mum of one studio strobe light with asoft box and one reflector will be needed(Figure 7). For portraits using this set-up, the strobe light should be positionedon one side of the subject and the reflec-tor placed on the other to reflect lightto that side and give a more even illu-mination. Another extremely simple,effective, and inexpensive way to achievehigh-quality portraits is using the Light-sphere II Inverted Dome Diffusion Sys-tem (Gary Fong Innovations, Mar Vista,CA). The diffuser attaches to a standardon-camera flash as shown (Figure 8).The diffuser bounces the light off thewalls and ceiling, giving surprisingly even and flattering illumination (Figure9 and Figure 10).

DENTAL IMAGESFOR ESTHETICSAND COMMUNICATIONThe American Academy of CosmeticDentistry recommends a series of imagesto give a complete picture of the patientsdental condition. This article features theminimum number of images to diagnoseand communicate esthetic issues bothwith the patient and the ceramist.

FULL-FACE IMAGESThe most critical images for macro-esthet-ics (the esthetics of the relationship of theface, lips, gingiva, and the teeth) are thefull-face images with the lips relaxed (theM position) (Figure 11) and the fullsmile (Figure 12).These images commu-nicate tooth display both at rest and smil-ing, the incisal plane, the gingival display,intertooth proportions, negative space(buccal corridor and lip-to-incisal edge),

and a preliminary impression of toothcolor and form. Much of the initial smiledesign is based on these two images.These images should be taken at f8 in APmode with the Lightsphere II Diffuser. Itis a good idea to take multiple images of these two positions to ensure a good andrepresentative image.

LOWER THIRD OF THE FACETwo images of the lower third of the faceare ideal: one image of the patient smil-ing (Figure 13) and one image of thecheeks retracted (Figure 14). Bothimages should be taken at f22 in AP

mode with the dual-point flash. Theseimages should be taken at the exact samemagnification ratio of 1:2 with the cam-era in the exact same position relative tothe patient. The occlusal/ incisal planeshould bisect the image and any cants tothe maxilla or incisal plane should berepresented in the image. The lens barrelshould be parallel to the horizon, not theocclusal plane. This will help visualizeeither the mediallateral or the anteri-orposterior occlusal plane and gingivalline problems. The patient should beupright (ie, the head should not be cant-ed in any direction) with the head in thepostural rest position. These images givea close-up view of how the lips, gingiva,and teeth interrelate. The view with thecheeks retracted gives a picture of themicro-esthetics (the esthetics of the indi-vidual teeth). Also, these two images canbe superimposed in either PowerPoint(Microsoft Corporation, Redmond,WA)or Photoshop and used to create a digitaldiagnosis and digital smile design.

CLOSE-UP IMAGESTo see the detail in individual teeth, aclose-up image should be taken at 1:1magnification (Figure 15). The image istaken at f22 in AP mode with the dualflashes. To view translucency, a usefultool is the Dental Contrastor (PhotomedInternational, Van Nays, CA) (Figure16). This tool allows either the maxillary anterior or mandibular anterior teeth tobe easily isolated (Figure 17).

SHADECOMMUNICATION IMAGESThe step-by-step process of taking ashade has been previously detailed. 2

There are two images necessary for shadecommunication. One image should betaken with the two closest value shadetabs to the teeth being matched. Ideally,one tab should be slightly higher in valueand one should be slightly lower invalue. The second image should be takenwith the two closest chroma matches tothe teeth. Again, one tab should beslightly higher in chroma and one slight-ly lower. This allows the ceramist to visu-alize contrasts between the shade guideand the natural teeth. The shade guideand the teeth should be wet with a liquidthat keeps the teeth hydrated. The authorsrecommend a medium viscosity glaze

liquid. The shade guides should be heldin the same vertical plane as the naturalteeth (Figure 18).

PHOTOSHOP TO ISOLATETHE SHADE IMAGESThere are many uses of Photoshop forimage management and color correc-tion. Photoshop is an ideal instrument toisolate (select out) the previously takenshade images and separate the shadeguides and the teeth to be matched fromtheir surrounding backgrounds. It ismuch easier to visualize color matches ormismatches when backgrounds are stan-

100 INSIDE DENTISTRY OCTOBE

Figure 17 Close-up image of maxillary anterior teeth taken using the dental contrastor.

Figure 18 An image of the two closet vain the same vertical plane as the natural te

Figure 19 The RAW file opened in Photoshop. There are two sliders, which are adjusted as neceto correct for exposure and color temperature problems.

Figure 20 The shade image with the teeth to be matched and the shade guides selected with onePhotoshops selection tools.

Figure 21 Image of the Photoshop interface with the fill dialogue box open (found in the edit m


4/4

INSIDE DENTISTRY OCTOBER 2006

dardized. The shade images should bedownloaded into the computer andopened in Photoshop in the RAW win-dow (the images have to be taken inRAW file format). The images can thenbe adjusted for exposure using the expo-sure adjustment slider and color-cast(white balance) using the color tempera-ture slider (Figure 19). Using one of theselection tools (either the polygon lassotool or the magnetic lasso tool), selectaround the shade tabs and the teeth to bematched (Figure 20). You actually wantto select everything outside of the selec-tion you just made (the surroundingbackground). To do this, go into theselect drop-down menu and selectinverse. This will now invert the selec-tion, deselecting the teeth and selectingthe background. Next, in the editdrop-down menu, click on fill. A dialogue

box will come up asking you to choose acolor (Figure 21).Choose the color black or a neutral gray and click OK. Theselected background will be filled withblack (Figure 22).At this point, duplicatethe image. In one of the images, go intothe image drop-down menu, click onmode, and then click on grayscale.This will turn the image to black andwhite (actually gray scale) (Figure 23).Save both the chromatic (color) imageand the black-and-white image. It is now very easy to compare the shade guidesagainst the natural teeth. These imagesalong with all of the previous images cannow be transferred to the ceramist.

CONCLUSIONWith an understanding of the tech-niques and armamentarium for photog-raphy and the use of Photoshop,todays practicing dentist can documentand treatment plan cases in more tech-nologically advanced ways than everbefore. Understanding these tools andtechniques will also prove to be invalu-able for communications between thedentist and the laboratory, other special-ists, and the patient.

REFERENCES1. McLaren EA, Terry DA. Photography in

Dentistry. J Calif Dent Assoc. 2001;29(10):

735-742.2. McLaren EA. The 3-D communication of shade.

Inside Dentistry. 2006;2:92-93.

Figure 22 The shade image with the back-ground filled with black.

Figure 23 The duplicated shade image turnedto black and white to evaluate value discrepancies.

Use a semiprofessional or professional dig-ital SLR (single lens reflex) camera that willcapture images in a RAW file format.

Use a macro lens for close-up photography.

Set the camera to f22 for close ups and f8for portraits.

Use either AP or manual exposure mode.

Spot meter the area of the scene youwant correctly exposed.

For optimal surface texture and translucen-cy,use a dual-point light source (flash).

RULES FORENSURING ACCURATE,REPRESENTATIVEDENTAL IMAGES

Documents

Del DSD Al PSD - 2006 Por McLaren