Digital Photography in Orthodon

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Digital Photography in Orthodontics

Introduction

Photographs are an essential part of clinical documentation. Current

‘best practice’ is a full set of extra- and intra-oral photographs, both at the

start and completion of a course of orthodontic treatment and, ideally, some

mid-treatment photographs showing key-stages in treatment (Sandler, 2000).

Photographs are an essential part of clinical records for a number of

reasons:

1. Unreliable memories. Within a matter of months, patients and parents

tend to forget how severe the original malocclusion was. Having slides

available at every visit reminds both the orthodontist and the patient of

the original situation, against which all improvements can be judged.

2. Medico legal requirements. In our increasingly litigious society, it is

critical to have clinical photographs that indicate any preexisting

pathology or trauma to the teeth. Close-up photographs are strongly

advised for any marked decalcification or enamel fractures that are

evident from the outset.

The debonding appointment is often the first time patients or

parents really focus in on the labial enamel, and it may be the first time



they actually notice surface decalcification, fractures, or other

blemishes. Proper records will help avoid any post-treatment disputes.

3. Teaching needs. Slides are probably the most important teaching aidsin orthodontics. If cases are to be used in lectures, posters, papers, and

presentations, a high standard of clinical photography is required.

4. Treatment evaluations. A quick scan of sequential slides with patients

and parents during treatment will save lengthy explanations of

biomechanics or tooth movements.

Digital photography has been generally available since 1981. In 1991

‘Autotrader’ were the first mass market publication to move completely to

digital recording of images. Now, many trades and professions, including

estate agents, advertising agencies, police, and the media use digital

photography on a routine basis.

Digital images are made up of picture elements (‘pixels’) comprising

red, green, and blue light, each set at a level between 0 and 255. If all three

colours are set at 255 white is the result, while if all are set at zero, black

results (Figure 1 ). There are 256 grey shades that result from all three

colours being set at the same number. Varying the level of each of the three

colours results in the gamut of 16•7 million colours. Numerical values for

each of these colours are stored on the Charged Couple device (CCD). This

is made up of pixels, the number of which, combined with the degree of

compression, determines the quality of the final output.



FIG. 1 Digital images made up of Red, Green

and Blue light at levels between 0 and 255. 16•7 million colors in all.

In the 1990s a typical CCD would comprise 640 x 480

pixels resulting in acceptable images for snapshots, but lacking the quality

needed for high quality clinical photographs (Figure 2 ). By 1999 the first

‘mega-pixel’ cameras (over 1,000,000 pixels per image) were becoming

available, but above 1•5 mega pixels the law of diminishing returns kicked in

with a disproportionate price increase for only modest improvements in

quality.



FIG. 2

Low pixel count (left) results in poorer quality image than required for

orthodontics(right).

Bearing in mind a conventional 35-mm slide is thought to

contain the equivalent of 25–30 million pixels of information there was still a

long way to go for digital images to be serious competition. In addition,

conventional photographic equipment for orthodontic images produced good

image quality, was very reliable and user-friendly (Sandler and Murray,

1999 ), and was relatively inexpensive.

However, well-recognized problems with conventional

photographic techniques are the cost of developing and processing films, the

time required for processing and physical storage of all the patients slides or

prints.

Digital photography offers many advantages including:

1. rapid turn-around;

2. checkable exposure accuracy;

3. no ageing of photos;

4. dust and scratches are irrelevant;



5. built in white balance;

6. immediate viewing;

7. no film or processing costs;

8. inexpensive storage;

9. easy retrieval;

10. duplication easy;

11. Transmission around the world in seconds is entirely feasible.

‘Prosumer’ cameras

One type of digital camera (prosumer) falls into the mid-range

price bracket £500–1500 and lies between the consumer camera and the

professional models. They usually have a host of useful features including

macro-zoom lenses and potentially high image quality. The ‘piece de

resistance’ of digital cameras is undoubtedly the image preview facility in

that images can be immediately viewed on the LCD screen and accepted or,

if flawed, deleted and retaken.

The problems with the ‘prosumer’ cameras used for orthodontic

photography are three-fold.

First, the flash provided with most digital cameras is a point flash.

Experience has shown that for high quality intra-oral

images ring flashes are

essential to avoid unacceptable shadowing on most of the images (Figure 3 ).

Despite the use of deflectors and diffusers the results with the built-in point

flash tend to be disappointing. The point flashes are also not powerful enough

to allow the photos to be taken on very small apertures (F32). This is essential



as it greatly increases the depth of field and ensures most of the frame is in

focus. In addition, even if it is possible to add a ring flash to the ‘prosumer’

camera high quality consistently exposed images require through the lens

(TTL) metering, which is not available on these ‘lower

end’ systems. After 20

years of ever increasing quality of orthodontic photography using SLR

systems, TTL metering, and ring flashes, some of the orthodontic community

are accepting mediocre photographs, taken with substandard digital equipment

just for the facility of immediate viewing.

FIG. 3 Point flash intra-oral images are invariably inferior to ring flash due

to shadowing and variable exposure.

It is possible to overcome some of the shadowing problems of a

point flash by modifying the technique used. Taking the occlusal shots from

much further away may ensure adequate illumination, but will inevitably

waste pixels unnecessarily and focusing

will also be problematic (Figure 4 ).

Turning the camera around on buccal intra-oral shots may also reduce

shadowing to a degree.



FIG. 4 Slightly different technique used for occlusal shots with point

flash—shadows less but pixels wasted.

The second problem involves the viewfinders; some digital

cameras are available with a ‘Galilean telescope’ viewfinder that is very

suitable for snapshots, but totally unsuitable for high quality intra-oral

photography. The problem is that the viewfinder, when close to the subject,

doesn’t accurately represent what the lens will ‘see’. Live display on the

LCD screen is also possible, but they are again inaccurate if the ‘refresh rate’

is slow, and are very power hungry, making it an unsuitable method unless a

mains supply is utilized.

Thirdly, the focusing system can be problematic as the

auto-focus systems on the ‘prosumer’ cameras are frustrating to work with

when capturing intra-oral photographs. They often take three or four

attempts to get the system to focus adequately, and all the area of interest is

not always as sharp as it might be. The predetermined distance ‘macro’

settings available on some of the digital cameras also sometimes give

disappointing results.

Professional cameras



Top end cameras have always been available. Indeed,

Kodak teamed up with Nikon in the late 1990s to produce the Digital

Camera System (DCS), which was capable of very high quality images. The

problem with this system was that the camera body alone

was over £10,000.

FIG. 5 Basic price of Nikon/Kodak DCS £10,495

The Nikon Dl is one of the best digital cameras and is the one used

by a great many photojournalists worldwide. It has a vast array of features

required by professionals, and the body is built out of titanium to an

incredibly high specification, for use in sandstorms, typhoons, and war zones

throughout the world. The problem with the Dl is that it is a very heavy

camera and would be difficult to hold with one hand, a technique essential

for high quality intra-oral images (Sandler and Murray, 1999 ). Also The

SB29 ring flash does not work as TTL metering with this body. Finally, a

price tag for the whole package of close

to £5000 makes it unaffordable for many clinicians.

Another digital camera recently released is the Fuji FinePix S1

Pro, which may be the perfect digital camera for orthodontics (Figure 6 ).



The body is made by Nikon and is therefore built to a high specification. The

lens system required is the Nikon 105 mm/2•8 AF Macro and the flash

system is the Nikon SB29 Speedlight. The flash provides TTL metering and,

therefore,

the intra-oral photos taken at F32 are invariably perfectly

exposed

and in focus. The pictures are all taken on manual focus just by setting the

lens adjustment for intra-oral shots, then moving backwards and forwards to

focus. Using the ‘limit’ switch on the lens allows the same magnification to

be set for all intra-oral photos, thus allowing direct comparability between

photos.

FIG. 6 Fuji Si FinePix Pro plus Nikon SB29 flash.

Images may be stored on a 64 Mb storage card. The capacity of

this card means that 330 images can be stored, using the lowest pixel setting

(1440) and maximum compression, resulting in images of about 200 Kb. The

quality of these images is more than acceptable for most clinical situations

(Figure 7 ). The images can still be cropped and enlarged as necessary

retaining sufficient detail for most situations.



FIG. 7 Top pictures with point flash and no TTL metering, bottom with

FujiS1Pro.

The only adjustment the camera requires is from F32 to F11 for

extra-oral shots and to switch off the flash bulb behind the patients head on

the three-quarter and profile view to throw the shadow behind the head.

MANIPULATION OF DIGITAL PHOTOGRAPHS

The requirements for successful use of digital images are a high

quality digital camera, and a sufficiently powerful computer to allow easy

viewing and subsequent manipulation of the images.

Most digital images are stored within the camera on either a

Compact Flash card (43 x38x3.5mm in hard case) or a Smart Media card(thinner, lighter, and more flimsy).

The former storage medium is probably more appropriate for a busy

clinical environment, as the latter requires delicate handling. Once the



images have been captured they need to be 'read' by the computer. At

present, the most convenient method is use of an adapter to allow the card

to be inserted directly into an empty PCM CIA port. On a modem laptop

this is the one occupied by the computers removable fax / modem or

alternatively by the network card.

PCM CIA card slots into the laptop

I.EXIF VIEWER



• Modern digital cameras are often sold with 'bundled' software

to allow viewing of images.

• Exif viewer is provided with many cameras, and if loaded

correctly, the 'thumbnails' (small representations of each picture on

the computer screen) are automatically loaded on the computer

screen when the memory card is accessed.

• ‘Thumbnails’ automatically appear in the Exif viewer

• Exif viewer also allows inspection of individual images, to

check entire area of interest is included, as well as confirming

sufficient depth of field was available to ensure the whole picture is

in focus.



• The Instant preview facility, on all but the cheapest digital

cameras' LCD screen, certainly gives an overall impression of the

image.

• It is only the top range cameras, such as the Fuji S 1 Pro, that

have a sufficiently high quality LCD screen combined with the

facility to scan the entire image easily with a powerful optical

zoom. This will allow quality verification by viewing on the camera

alone.

Images taken with mid-range cameras may need quality confirming,

using Exif viewer, before the patients are sent home.

Each image can be checked for quality.



Once all the images are satisfactory, Dento facial Showcase is

opened alongside Exif viewer. The 'Restore Down' button is now used

(top right of the screen, button next to Close Program button) for both

programs, to allow them to be visible on the screen at the same time.

All of an individual patient's images are now selected in Exif

Viewer (left mouse button, whilst holding down the Ctrl key) and these

are dragged and dropped into a previously opened new file in Showcase.

In a busy clinic, particularly where images are not necessarily

downloaded from the card after every patient, it is important to write

down the patient's name on paper. This name should be photographed to

allow subsequent identification of patients.

This is essential if many clinicians use the camera, particularly if

the cards are filled to capacity before a backup is made.

II. DENTO FACIAL SHOWCASE



• Showcase is a popular program for storing, manipulating, and

showing orthodontic records of patients, in an informal setting.

• Thumb nails are stored under each patient's name, and

attributes such as type of photograph and stage of treatment can be

easily attached to individual images, or groups of images.

• Slides of particular interest can be selected within Showcase

to run a slide show to illustrate the features of the patient's

malocclusion.

• Individual slides can be presented in order to show

maximum detail of each view taken. Alternatively a selection of

views can be incorporated with in a single 'slide' for a less detailed,

but more comprehensive over view of the case

•

•





The image will probably need to be resized with in PowerPoint and then

the process is repeated for further images.

The advantage of the PowerPoint slides is that the relative size and

position of the individual images is infinitely variable and maximum

space can be occupied by material of interest.

Intra-oral slides are scanned into PowerPoint and all five views can

be incorporated into one slide to give the 'full picture' of the malocclusion

and treatment at that point in time.

Radiographic information should also be imported in to the

computer. The lateral cephalometric radiograph and OPG can either be

scanned, if the scanner has a transparency adaptor, or alternatively

photographed with the digital camera.

The flash is turned off and the camera aperture opened sufficiently

wide to reduce the shutter speed to 125 or faster, to eliminate camera

shake. The ideal background is an outside window, using daylight to

trans-illuminate the film avoiding the greenish hue inevitable when an X-

ray viewer is used for illumination.

Radiographs captured digitally & converted to gray scale





All the information on particular patients can be presented to

patients, individual colleagues or a large audience in a clear and concise

manner, which can serve as an aid to future diagnosis and treatment

planning.

SOURCES OF ERRORS IN CLINICAL PHOTOGRAPHY

Clinical photographs taken before, during and after orthodontic

treatment form an essential part of the patients' records. If correctly taken,

they offer more useful information about the malocclusion and treatment

than any other clinical record. There are, however, many potential sources of

errors whilst obtaining these invaluable records. Photographs of inadequate

quality may misrepresent the patients starting malocclusion, may

inaccurately reflect progress with treatment or may inaccurately record

dental anomalies and defects that may be present.

With both conventional and digital systems, many of these

errors, which involve use of mirrors and retractors and patient positioning

issues, are common to both methods. With the recent widespread use of

digital equipment a whole new range of possible errors has been introduced

and specific problems related to the digital system are discussed in detail.

There are a number of errors that are commonly seen and these

can be divided into two groups.

• The first group comprises errors due to inappropriate choice or

use of equipment including the camera, lens, flash, retractors, mirrors

or suction, or a lack of understanding of the digital technology resulting

in inadequate or inappropriate images.



• The second group of errors relates to any recording medium and

involves inappropriate positioning of the subjects.

Technical errors

1. Camera

2. Retractors

3. Mirrors

1.

Camera.The correct equipment is required for high quality clinical

photographs, which include a camera (either conventional or digital) with

a macro-facility (ability to produce I : I images) and, ideally, a ring flash,

an appropriate background, suitable lighting and well trained assistants.

Correct camera orientation is important, with extra-oral

photographs taken in portrait mode and intra-oral photographs taken in

landscape mode. To allow direct comparison of photographs taken at

different times consistent magnification of images is required.

To aid this with conventional equipment a label can be placed

on the barrel of the lens indicating the required lens setting (focal length)

for each of the standard views .



The magnification will therefore be preset for intra-oral, mirror and extra-

oral views allowing direct comparison of sequential shots. The lens barrel

is set to the predetermined position and the subject brought into focus by

moving the camera closer to or further from the patient.

With digital images this is not such a critical issue as they can

be resized at a later stage to allow comparison with previous or

subsequent images providing there is sufficient information on the image

to guarantee quality, once cropped and resized. This is determined by the

number of picture elements (pixels) on the charge-coupled device within

the digital camera and whether the area of interest completely fills the

recorded area. Most modern digital cameras record 3 mega pixels or

more, which is more than adequate for high quality clinical photography.

2.Retractors.

Two sizes of double-ended retractor are prerequisite to

obtaining a set of high quality intra-oral photographs.



The large ends of the larger retractor are used to obtain retraction for the

anterior intra-oral shot. The assistant should hold both retractors pulling

them both laterally and also forwards, which is the opposite to the natural

instincts of the assistants when retracting. By pulling the lips forwards

towards the photographer it makes it easier for the patient to bite together

in occlusion and pulls the soft tissues away from the teeth.

For the buccal shots, one retractor is turned through 180°, thus using

the smaller end of the larger retractor on the side of interest. The

photographer should hold this retractor themselves and, immediately before

capturing the image, pull it an extra 4-5 mm both distally and away from the



teeth to ensure at least the distal of the first molars is captured. To allow

optimal soft tissue retraction the assistant passively holds the large end of

the large retractor on the opposite side

.

For both occlusal shots the assistant inserts the small ends of

the small retractors under the respective lips and rotates them towards the

midline pulling the lips forward, as well as laterally. This is essential to

prevent obscuring the teeth with the lips. The direction of pull is away

from the teeth, and upwards for maxillary shots and downwards for

mandibular shots, thus ensuring a background of reflected mucosa rather

than stretched vermillion.



3. Mirrors.

Long-handled, front-silvered, glass mirrors are the ideal tool for

clinical photography, although they are significantly more expensive than

rear-silvered or metal mirrors. Long handles are held by the photographer to

allow complete control of the picture and to keeps assistants fingers out of

the shot.

Glass mirrors produce a far superior photograph compared to

polished metal mirrors as there is much greater reflection of the light and

they are more resistant to scratching. Silvering on the front side of the mirror

prevents double images, which occur due to a second reflection from the

glass surface when the silvering is on the back surface.

Ghost image from glass and image Sharp image when front silvered

from rear silver Surface is used

Prior to taking the photograph the mirror should either be warmed to

prevent misting of the mirror when it is inserted into the patients' mouth or the patient should be instructed to hold their breath for 10 seconds or so.

The occlusal mirrors are available in three different sizes; however, the

two smallest sizes are required in less than 10% of patients.



During occlusal photography light is never reflected 100%, and there is a

tendency for mirror photographs to be slightly underexposed.

It is therefore worth using an aperture compensation of + 1 F-stop, to ensure

good illumination of mirror shots. This adjustment can be usually made on

both conventional and modern digital camera systems.



Problems related to Digital Photography

1. Depth of field.*

2. Auto focus.*

3. Shadows.*

4. Constructing symmetrical images.

5. Image storage.

6. Digital image- fit for purpose?

*Problems frequently encountered when using midrange 'Prosumer' cameras.

Depth of field problems.

The depth of field represents the amount of the image that

is in sharp focus, and is dependant upon magnification and the aperture

selected. As the magnification increases and as the aperture through which

the picture is taken widens the depth of field reduces. Many mid-range

digital cameras that bridge the gap between consumer and professional

models, (known as 'Prosumer' cameras, e.g. Nikon Cool Pix 990/4500) will

only allow the aperture to be reduced to about Fll.

When taking intra-oral photographs with these mid-range

cameras the depth of field will be relatively small and on the anterior intra-

oral photograph part of the picture will inevitably be out of focus.



The depth of field is distributed approximately one-third in front and

two-thirds behind the focal plane. This disadvantage of small depth of field

with pictures taken with larger apertures can be minimized (but not avoided

completely) by focusing on the distal surface of the lateral incisors to at least

get central incisors to canines in focus.

With professional digital cameras, e.g. Fuji Sl FinePix Pro, combined with

the powerful Nikon SB29 flash, which allows through the lens metering a

perfect exposure is possible on F32. This tiny aperture allows sufficient

depth of field to include both incisor brackets and second premolar bracketsin sharp focus provided the focal plane is positioned correctly, i.e. on the

mesial of the canines.



With buccal shots and occlusal shots, provided the subject is correctly

positioned and retractors are appropriately used, all the area of interest is on

one plane; therefore, depth of field should not be an issue.

Auto-focus problems.

Digital cameras often allow the choice between auto-focus or

manual focus. Manual focus is by far the preferred option for the following

reasons. With Prosumer cameras focusing have to be on the lateral incisors

and with top end cameras on the canines, whilst still maintaining a centered

photograph. Because of the lack of sharply contrasting lines in the area of

interest many of these digital cameras have difficulty focusing using the

auto-focus setting for intraoral photographs. The result of this is attempt

after attempt to get the camera focus light (usually flashing green) to stop

flashing, indicating that the shot is in focus. This often proves fruitless

despite repeatedly moving the camera slightly between attempts at focusing.

All this is occurring whilst the assistant and the clinician are heaving on the

retractors to get maximum retraction of the soft tissues and some patients

may find this a little uncomfortable.



Frustrating attempts to get auto focus to work.

The solution to this problem is to use the manual focus setting

for all clinical photography. With top end cameras with through the lens

(TTL) facility focusing is done looking through the viewfinder. With the

Prosumer models, the clinician decides the appropriate distance between the

patient and the camera that fills the frame with the area of interest, This

focusing distance of, for example, 0.2 m, is set manually on the camera, and

the camera is then merely moved backwards and forwards until the image on

the LCD screen is in sharp focus, and the picture is taken. Twenty

centimeters is a good distance to start testing the cameras ability to take

sharp anterior intra-oral photographs on manual setting.



For extra-oral photography an attempt should be made to focus

on the patient’s lower eyelid to ensure from the tip of the nose to the ear of

the patient falls within the depth of field on the front, three-quarter and

profile views.

Using the dental light to illuminate the patient not only helps to reduce

red-eye, but also greatly aids focusing in poorly lit surgeries.

Shadows

Problems involving shadowing are almost inevitable with

Prosumer digital cameras that use a paint flash. If the flash is mounted to one

side of the lens this shadowing is particularly noticeable on the lateral shot

and on the anterior shot if the flash is above the lens.



Various mirrors, reflectors and diffusers have been suggested in the past to

reduce this problem; however, none provide the perfect solution and the

additions tend to make the set-up unwieldy to use.

The other alternatives are either to use an illuminated screen as the

backdrop to the patients when taking the extra-oral photographs, or use a

dark non-reflective background (preferably velvet) to maximize the quality

of the image.

With intra-oral views again the solution with a side mounted point

flash is to turn the camera upside down on the buccal view with the very

dark buccal corridor. This will ensure the flash illuminates the area that

would otherwise be in shadow due to the cheek. This digital photograph can

then be rotated 180º before the picture is saved in the patients file.

Dark right buccal corridor as Shadow overcome byCheek prevents light from Left turning Camera through 180 º

Mounted flash. So the flash is now on left.



High quality occlusal photographs are also difficult to obtain using

cameras with point flashes with the usual magnification, because of the

proximity of the camera to the patient; much of the area of interest is in

shadow

.

One solution to the problem of inadequate illumination is to focus further

away from the patient, which allows more light in and therefore reduces

shadowing. In this situation, the area of interest only fills about 20% of the

area captured by the camera so the charge couple device must be of high

enough quality to produce a good image after 80% of the information

captured has been discarded .



Constructing symmetrical images.

One major advantage of the very popular Dental Eye 3 camera,

over many of its competitors, was the presence of a graticule in the

viewfinder. This allowed very well constructed symmetrical and balanced

intra- and extra-oral photographs to be taken, even by relatively

inexperienced photographers using the occlusal plane the interpupillary line

and the Frankfort plane to construct reproducible photographs.

Most of the midrange digital cameras do not have the benefit

of a graticule to help with construction of the photographs, but some of the

top end cameras, e.g. the Fuji FinePix S2 Pro, have 'on-demand' grid lines,

which help significantly with construction of the extra-oral and intra-oral

images.

Card problems. The digital images are often recorded onto PCMCIA

cards. These cards have a series of 50 small holes that accept 50 tiny metal

pins within the camera. Small imperfections in the PCMCIA card may

damage the pins and once damaged will necessitate return of the camera to

the manufacturers for repair.



CCD problems. Even when the lenses on the digital cameras are

never changed dust may still eventually get onto the CCD of the cameras.

This will be seen as tiny 'in focus' black marks, at a specific spot on intra-

and extra-oral images.

Hairs and dust eventually get onto the CCD

On SLR type cameras it is often possible to get access to the CCD to

allow it to be cleaned with optic cleaning liquid on lint-free non-abrasive

cloths, but this must be done with extreme care. If in any doubt at all the

camera should be returned to the manufacturer for this to be carried out.

Digital image: fit for purpose?

Most digital cameras come with a variety of settings and it is

sometimes difficult to know which is the best setting to use in any particular

situation. The questions that need to be answered are what will the digital

image be used for, is memory card space at a premium and will the images

ever be used to produce hard copy?

When deciding upon the type of image there are choices about the

pixel dimensions. These may be 3040, 2048, or 1024 pixels across the wider

dimension of the image. (Cheaper cameras have even smaller dimensions of

images, but the quality of these is usually unacceptable for clinical



purposes). If the image is only ever to be viewed on a computer screen, there

is little point having more information available than can be exhibited on the

screen, or displayed using a laptop projector. The average screen has 1024

pixels across, so if a landscape image is going to occupy the whole screen

1000 pixels across will be the setting of choice, reduced proportionally as

the area of the slide occupied by the image is reduced.

.

Keeping images as small as possible will ensure that the

slideshows into which they are imported are a manageable size, and that the

computers do not struggle when displaying the slideshow. When creating an

orthodontic slideshow an image will often only occupy half of the screen so

the image size can be reduced further, to 500 pixels on its horizontal axis,

using any of the commonly available image manipulation programmes, prior

to insertion into the slide show.

This is preferable to grabbing the corners of a grossly oversized

image and 'squashing' it to within the dimensions of a PowerPoint slide, as

all the superfluous 'memory hungry' information is still within the file

making the slideshow unnecessarily large and often unwieldy. On most

digital cameras there is also a setting for image quality, as various degrees of



compression are used to reduce memory requirements. A common situation

is for the camera to save files at maximum quality with no compression as

TIFF files and to have 2 or 3 levels of JPEG compression represented by the

'fine', 'normal' and 'basic' settings. Roughly, the file sizes are reduced to 1/4,

1/8 and 1/16 of the original file size by successive compressions. The

'normal' setting produces images that are adequate for most purposes, and

the 'High', and 'Fine' settings are generally required when hard copy prints

are required.

If there is a possibility that the digital image will need to be

printed at some stage then for photographic quality printing a resolution of

approximately 300 pixels per inch is required. For a good quality 6 x 4 inch

print the image needs to be taken with the 2048 pixel setting across its

longer dimension. Images taken for publication purposes, therefore, need to

be of a higher size and ideally higher quality (less compression) than those

taken for routine patient records.

The typical setting for standard digital photographs using a Fuji

FinePix S2 Pro is the 1440 setting on 'normal' for the intra-oral photographs

and using a + 1 compensation for mirror shots. The aperture of the camera is

set at F32 for both types of intra-oral photographs and F5.6 for extra-oral

photographs.

Positioning errors

Both the patient and the clinician need to be positioned

correctly, in a standardized manner, to produce consistent photographs. All

features of the malocclusion should be demonstrated, and areas of interest

not obscured by clothing, hair, impression material, retractors or saliva.

Problems may be encountered where there is a height difference



between the patient and the clinician, and it may not be possible to get a

uniform background as the photographs may appear to be taken above or

below the patient. This problem can be solved by getting the patient or the

clinician, which ever is appropriate, to stand on a platform to raise them to

the same height.

The required photographs and the objectives for each shot have been

previously outlined.

I. Extra-oral photographs

include a full face view, a full face smiling view, a profile

view and a three-quarter profile view, and the intra-oral photographs include

an anterior view, and right and left buccal views of the teeth in occlusion,

and upper and lower occlusal views.With all cameras time must be spent calibrating the system to

determine the optimal settings for both intra and extra-oral photographs.

Intra-oral photographs should be taken with the smallest aperture possible to

maximize the depth of field.



Extra-oral photographs

Full face and full face smiling views

Ideally, this is a 'portrait' view with the face filling the frame

extending to just above the top of the head and just below the chin. The

photograph should be symmetrical with the interpupillary plane parallel to

the floor. If possible, the dental light is directed towards the patient to

constrict their pupils to minimize any 'red eye' effect.

The first photograph is taken with the lips at rest and the next

one with the patient grinning broadly showing their Teeth. Commonly seen

features of a poor extra-oral shot include the photograph taken in landscape

orientation, at the wrong magnification and too much of the patient's torso in

the photograph.

An appropriate and consistent background should be selected,

such as a blue non-reflective material, or alternatively to eliminate shadows

completely a light box. Soap containers, light switches, door handles and

edges of notice boards add 'noise' to the view and detract from the overall

quality of the final picture.

It is important to give clear and concise instructions to the patient.



Occasionally, when asked to stand in front of the background, patients will

take the instructions too literally and turn their back to the photographer,

highlighting the need for explicit patient instructions.

Profile and three-quarter profile views

Usually only one profile (the patients right profile to match up

with the lateral cephalograms and tracing) is taken. However, for patients

with facial asymmetries both right and left profiles should be taken. Again,

the face should fill the frame extending to above the top of the head, in front

of the nose and below the chin. The back of the head is not necessarily

required and it reduces the size of the frame occupied by areas of interest.

The patient's Frankfort plane should be horizontal. The dental light, if

required, should be directed so that the patient's shadow is thrown behind the

patient and the camera's flash, where possible, should be adjusted for similar

effect.

Errors with profile shots include a misrepresentation of the soft

tissue morphology or skeletal pattern and this may be due to patient

posturing or alternatively excessive tilting of the head forwards or

backwards.



Subjects with long hair should always be asked to tuck it behind their ears

so that the Frankfort plane may be assessed accurately and the area of

interest is fully exposed.

Intra-oral photographs

Anterior views

This is taken in 'landscape' view, with the teeth in occlusion filling

the frame, with the occlusal plane horizontal and bisecting the picture. Once

the correct retractors have been selected all soft tissues should be retracted

away from the teeth laterally and anteriorly. The midlines, if they are



correct, should be in the centre of the frame. One possible error, although

relatively uncommon, is taking an intra-oral shot in portrait orientation.

Common errors include canted occlusal planes, inappropriate

selection and use of cheek retractors. Another totally preventable error is

saliva not aspirated or the tongue not retracted before the photograph is

taken, and bits of alginate left on the teeth. It is therefore worth familiarizing

the assistants with the retractors, always having good suction available and

taking photos before impressions when collecting records.

To aid focusing for intra-oral photographs the dental light should

always be shone directly into the patients' mouth. Adequate depth of field is

required particularly for the anterior photograph, so it is important to focus

on the level on the lateral incisors to ensure that the maximum numbers of

teeth are in focus.

Buccal views

Again the occlusal plane should be horizontal and bisect the frame.

The frame should be filled with teeth extending from the mesial surface of

the central incisor to at least the distal surface of the first permanent molars

and further posteriorly if possible. It is important to angle the camera so that

the lens is perpendicular to a tangent to the buccal surfaces of the posterior

teeth to avoid underestimation of the sagittal discrepancy, which occurs

through a 'parallax' effect.



Mirror views

The upper and lower mirror shots should ideally be

symmetrical views of the occlusal surfaces of the teeth, extending from just

in front of the incisors to at least the distal surfaces of the first molars and

ideally to include all the erupted teeth. There should be no direct view of the

mcisor teeth. Whilst setting up for the mirror shots move the patient by

tilting their head back so that the photographer doesn't have to stoop or twist

excessively. There is always a tendency for patients not to open their mouth

fully for these occlusal shots. To avoid this problem, after placing the mirror

and just prior to talking the shot ask the patient to open 'twice as wide',

which usually provides significantly better opening for the shot.

Remember that whatever is seen through the viewfinder

is invariably what will reproduced on the final photograph. Photographs

taken with a mirror require the aperture compensation setting on the camera

to be changed to + I to allow more light in. The differences between 0

setting and + I are small, but demonstrate slight underexposure of the shot

when mirrors are used with no compensation.



The effect aperture compensation for mirror shots.

With conventional slide photography never trust the last slide on the film as,

during processing, the ends of the films are joined together and this may

result in exposure to light thus spoiling the last frame. Therefore, always

settle for 36 shots per film and rewind at that stage, rather than attempting to

squeeze another I or 2 prints on the film.

Many of the aforementioned errors can be overcome with meticulous

attention to technique and the use of digital photography. Positioning errors

and camera errors are noticed immediately on the LCD screen, which is a

major advantage of digital photography.

Other errors can sometimes be compensated for by image



manipulation at a later date, but this is not without its disadvantages.

Rotation of images for example will lead to distortion of straight lines and

thus 'steps' in arch wires.

Resizing digital images is of course possible, but information is

unnecessarily sacrificed if the frame area is 'wasted' by filling it with areas

of no interest. Some programmes such as Dolphin TM allow guide lines to

be used when resizing images so consistent magnification is almost

guaranteed. The principles of use of retractors, mirrors and suction are

identical whether using conventional or digital equipment.

Conclusions

Good quality accurate clinical photographs can easily be

obtained using the correct equipment and appropriately trained staff. An

awareness of all the possible errors in extra- and intra-oral clinical

photography will increase the chances of obtaining high quality images.

References



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