in Dentistry
Photography
in Dentistry
Theory and Techniques in Modern Documentation
Pasquale Loiacono,
Private Practice, Tropea, Italy
Luca Pascoletti,
Private Practice, Udine, Italy
Contents
Contents
Foreword......................................................................................................11
Preface........................................................................................................13
Part I
Theory..................................................................................................... 15
Chapter 1
General Principles of Photography. ......................................................... 17
Close-up Photography........................................................................... 20
Basic Components of the Camera............................................................... 22
Compact and Reflex Cameras. .................................................................. 22
Components of a Digital Camera. .............................................................. 24
Analog and digital sensors............................................................... 24
Analog and digital sensors............................................................... 25
Aperture or diaphragm................................................................... 28
Shutter and shutter speed. .............................................................. 30
Reciprocity law. ...........................................................................31
Viewfinder. ............................................................................... 34
Live view and video modes............................................................... 36
Lens........................................................................................ 36
Exposure meter........................................................................... 37
Through-the-lens metering.............................................................. 37
Correct Handling of the Camera................................................................ 38
Camera Choice on the Basis of Documentation................................................ 40
Chapter 2
The Optical System............................................................................. 46
Principles of Vision .............................................................................. 46
Focal Length...................................................................................... 51
Angle of View and Magnification Factor....................................................... 53
Concept of Normality and Classification of Lenses............................................ 56
Meaning and Interpretation of the Magnification Ratio...................................... 60
Elements of Visual Tension. .................................................................... 65
Golden Questions................................................................................ 66
Importance of the Distance Between Lens and Subject....................................... 68
Perspective Distortion........................................................................... 68
Macro Lenses..................................................................................... 70
5
Contents
The Gold Standard for Lenses in Dentistry ..................................................... 70
Visualization of the Magnification Ratio....................................................... 71
Chapter 3
The Concept of Exposure. ..................................................................... 76
Definition of Exposure........................................................................... 76
Role of the Exposure Meter...................................................................... 78
Through-the-Lens Reading...................................................................... 78
Exposure Lock and Measuring Procedures..................................................... 79
Reflectance and the Standard 18% Gray Card................................................... 80
Exposure Correction............................................................................. 81
Physiology of Vision: Contrast Effects.......................................................... 85
ISO Speed......................................................................................... 88
Perception of Color and Color temperature..................................................... 90
White Balance ................................................................................... 94
Photography for the Communication of Color................................................. 96
Chapter 4
Principles of Digital Photography. .........................................................100
Sensors in Analog Photography................................................................ 101
Digital Sensors.................................................................................. 102
Photosites, Photodetectors, and Pixels........................................................ 107
Equivalent Focal Length and the Multiplication Factor...................................... 109
Image Circle and the Vignetting Concept..................................................... 110
Actual and Nominal Magnification Ratio......................................................112
Analog-to-Digital Converter.................................................................... 115
Image File Formats...............................................................................117
JPEG format...................................................................................... 118
Raw Format. .................................................................................... 118
Legal Value of the Raw Format................................................................. 120
Image Processing. ...............................................................................121
Shooting menus..........................................................................121
Resolution and Image Quality................................................................. 123
Image Depth and Color Space.................................................................. 126
Chromatic interpolation................................................................ 126
Memory Cards................................................................................... 128
Image Transfer to a Personal Computer....................................................... 130
6
Contents
Chapter 5
The Role of Photography in Clinical Practice.............................................. 134
A New Concept: The Photograph as a Diagnostic Instrument............................... 134
Communication with the Patient. ............................................................ 136
Medicolegal Value of Photographic Documentation. ........................................ 138
Communication with the Scientific Community............................................. 140
Photography as an Instrument for Self-assessment.......................................... 140
Photography for Communication with the Dental Laboratory.............................. 142
Chapter 6
Camera Settings for Dentistry............................................................... 146
Automatic Exposure Settings.................................................................. 146
Automatic Focus Settings...................................................................... 152
Depth of Field................................................................................... 154
Factors That Influence Depth of Field.......................................................... 155
Circles of confusion. .................................................................... 158
Circles of confusion...................................................................... 158
Relationship Between Focal Length and Depth of Field...................................... 159
Camera Settings Related to Clinical Requirements........................................... 160
Chapter 7
The Orthography of Images.................................................................. 164
Concept of Framing............................................................................. 164
Accessories for Intraoral Photography: Retractors and Mirrors. ............................ 164
Characteristics of Mirrors for Dental Photography........................................... 166
Aiming and Focal Points. ...................................................................... 166
Focusing Technique............................................................................. 168
Spatiality of the Frame and Orthography of Images. ........................................ 171
The Fundamental Rule for the Orthography of Images: Zero Coordinate .................. 173
Zero-Coordinate Rule Applied to Various Images............................................. 178
Creative Photographs........................................................................... 179
Contrast in Photography....................................................................... 182
Contrastors...................................................................................... 182
Intrinsic Optical Properties of Teeth: Translucency.......................................... 184
Extrinsic Optical Properties of Teeth: Surface Characteristics............................... 188
Chapter 8
Flash Units..................................................................................... 196
Traditional Flash Units......................................................................... 196
Ring Flashes.....................................................................................200
Twin Flashes. ................................................................................... 202
Creative Use of Flashes ......................................................................... 204
Flash Synchronization..........................................................................206
Exposure and Flash: TTL Mode.................................................................206
Manual Mode. .................................................................................. 207
7
Contents
Chapter 9
Photographing Radiographs.................................................................
Radiographic Masks............................................................................
Camera Settings................................................................................
Correct Framing.................................................................................
212
212
213
216
Part II
Techniques ..................................................................................... 221
Chapter 10
Equipment and Accessories.................................................................. 223
Cameras and Accessories....................................................................... 224
Intraoral mirrors. ....................................................................... 226
Cheek retractors......................................................................... 228
Additional accessories................................................................... 230
Image Quality................................................................................... 232
Synergy Between Practitioner and Assistant ................................................. 234
Chapter 11
Extraoral Series................................................................................ 236
View 1 Frontal Face, Smiling and with Lips Relaxed......................................... 240
View 2 Profile, Smiling and with Lips Relaxed................................................ 242
View 3 Slight, Average, and Maximum Smiles............................................... 244
View 4 Lateral Smile............................................................................ 246
Chapter 12
Intraoral Series................................................................................ 248
View 5 Right Overjet............................................................................ 252
View 6 Left Overjet.............................................................................. 254
View 7 Full Arches in Normal Occlusion....................................................... 256
View 8 Anterior Sextants in Normal Occlusion............................................... 258
View 9 Right Quadrants in Occlusion ........................................................ 262
View 10 Right Posterior Sextants in Occlusion ............................................... 264
View 11 Right Quadrants in Occlusion for Orthodontic Documentation ................... 266
View 12 Left Quadrants in Occlusion .......................................................... 268
View 13 Left Posterior Sextants in Occlusion ................................................. 270
View 14 Left Quadrants in Occlusion for Orthodontic Documentation..................... 272
View 15 Complete Maxillary Dentition: Occlusal View....................................... 276
View 16 Maxillary Anterior Sextant: Incisal View. ........................................... 278
View 17 Maxillary Anterior Sextant: Palatal View ........................................... 280
View 18 Maxillary Anterior Sextant: Facial View............................................. 282
View 19 Complete Mandibular Dentition: Occlusal View .................................... 284
View 20 Mandibular Anterior Sextant: Incisal View.......................................... 286
View 21 Mandibular Anterior Sextant: Lingual View......................................... 288
View 22 Mandibular Anterior Sextant: Facial View...........................................290
8
Contents
View 23 Maxillary Right Posterior Sextant: Occlusal View................................... 292
View 24 Maxillary Right Posterior Sextant: Palatal View. ................................... 294
View 25 Mandibular Left Posterior Sextant: Occlusal View.................................. 296
View 26 Mandibular Left Posterior Sextant: Lingual View................................... 298
View 27 Maxillary Left Posterior Sextant: Occlusal View.....................................300
View 28 Maxillary Left Posterior Sextant: Palatal View. ..................................... 302
View 29 Mandibular Right Posterior Sextant: Occlusal View................................ 304
View 30 Mandibular Right Posterior Sextant: Lingual View.................................306
Chapter 13
Photographic Documentation...............................................................309
Orthodontic Documentation .................................................................. 312
Periodontal Documentation.................................................................... 315
Prosthetic Documentation..................................................................... 319
Conservative Dentistry Documentation....................................................... 319
Photographing with rubber dam....................................................... 324
Communication with the Dental Laboratory Technician.................................... 326
Recommended Reading............................................................................. 329
Photographic references............................................................................. 333
9
Dedication
To my two wonderful daughters, Martina
and Nicoletta. May they always believe in
the beauty of their dreams and have the
strength to realize them.
Pasquale Loiacono
10
To my beloved daughter, Alice, an
irreplaceable source of energy, and
to my great friend and master of life,
Sandro Rodaro.
Luca Pascoletti
Foreword
Foreword
Writing the foreword to a text requires a great
moral and ethical commitment and, I would
add, is an important responsibility toward both
the authors and the readers. When my friends,
Pasquale Loiacono and Luca Pascoletti, the
authors of Photography in Dentistry, asked me
to write the foreword to their book, I was pleased
and honored to give a brief introduction to this
work for two reasons. First, I have known the
authors for several years and have followed the
path of their professional growth; second, they
are dear friends, and I feel a particular bond of
affection toward them.
The major innovation represented by this text
is the formation of the team of the two authors,
who possess extraordinary qualities and gifts.
This fine union of distinct talents has resulted
in a work that is scientific and, at the same
time, practical. The authors have interacted
well together to create a text that is cohesive
and extremely useful from a didactic point
of view. It provides the reader—the novice or
expert dentist-photographer—with a complete
guide for obtaining excellent photographic
documentation.
I can only express my most sincere
compliments to the two authors for achieving
a work in which the content and form is well
rounded, complete, and supported by excellent
illustrations—in other words, a work which
I would have been pleased to have written
myself. I am, therefore, convinced that this
book will be greatly appreciated and put to good
use by both novice dentists, aiming to acquire
the techniques of photography, and skilled
clinicians, who will certainly find theories and
ideas to put into practice straightaway.
With my most sincere compliments,
Domenico Massironi, MD, DMD
Private Practice
Milan, Italy
11
12
Preface
Preface
The idea of creating a manual of photography
for dentists originated from a specific cultural
frame of reference, the Massironi Study
Club, which is based upon the philosophy
and teachings of Dr Domenico Massironi.
We consider this work to be one of the many
fruits borne from the tireless and visionary
work of our “Maestro.” We are aware that he
is not keen on being defined in this manner;
however, the influence of his teachings and
his scientific rigor leads us to consider him
with such profound affection and respect
that we are unable to express ourselves in
any other way. Thus, a warm thank you goes
to him and to all friends of the Massironi
Study Club with whom we share an exciting
journey of personal and professional growth.
Why a book on photography?
First, we love and strongly believe in
photography as a fundamental means towards
our professional evolution. On a daily basis,
it allows us to verify the path of our learning
and to relate, in a positive way, to patients
and colleagues alike. Our love of photography,
together with our love of our profession, has
always led us to wonder how so many competent
professionals consider themselves unable to
take photographs that are comparable to the
quality of their own work. This false conviction
deprives them the opportunity to be appreciated
by a wider audience or, more simply, to record
their own professional path.
Our second fundamental motivation is an
awareness that the current approach towards
dental photography is totally lacking in
standardized procedures or agreed-upon rules,
which are present in all other traditional
dental disciplines. Many colleagues turn
to nonspecialized photographers to obtain
information or to learn how to take dental
photographs. However, the answers they
receive are vague and often based on strictly
commercial interests rather than the outcome
of rigorous scientific reasoning.
We believe that any dentist can quickly
acquire the rudimentary skills needed to take
more-than-adequate photographs or, with
very little extra effort, even excellent ones.
The real problem is that there are very few
comprehensive books on photography designed
and written by dentists for dentists. Because
we believe that only an insider can be aware
of the day-to-day problems that we face in our
profession, we were keen to put our knowledge
at the disposal of our colleagues, in the hopes of
spreading the use of this valuable instrument.
Pasquale Loiacono and Luca Pascoletti
13
Contents
Acknowledgments
My thoughts of gratitude and immense
affection go first to my family: to my wife,
Marianna, and my daughters, Martina and
Nicoletta, for all the time I have taken away
from them and, in particular, to my daughters
for their contribution as models in this book.
I would also like to thank Dr Domenico
Massironi for the great affection with which he
has always supported, guided, and motivated
me in both my personal and professional
growth; my friend, Dr Bruno Alia, for his
competent advice on medicolegal matters;
Professors Luciano Meligrana and Aurelio
Piserà, for their masterly stylistic advice; my
dental technicians, Marcello Aiello, Gianluca
and Francesco Barbagallo, and Evio Sirianni,
for the professional passion and friendship that
we share; Rosemary Barber, for her valuable
collaboration in the translation of the text;
Marco Forelli, for the skills that he has put at
my disposal; Fabio Rodaro, for the attention he
has devoted to my ideas and the care and skill
with which he has executed the illustrations;
my friend, Salvatore Accorinti, for the long and
valuable conversations about computing and
various methodologic and technical details.
Another thank you goes to my close friend,
Nando Ricciardi, the first person to believe in
this project, for the support and affection he
has always shown toward me.
Pasquale Loiacono
I would like to thank my great friend and Maestro, Dr Domenico Massironi, who has proved
to be an invaluable guide both in my life and
my profession. He has believed in and supported this project, providing us from the outset
with important and essential advice. I would
also like to thank my model, Sara Lirussi, who
has willingly and patiently sat for numerous
photographic sessions.
Other thanks go to expert professional photographer Alberto Cuoco, for the simplicity with
which he has performed the often tricky photographic sequences and the skill with which
he has demonstrated the positioning of the
operators and the photographic equipment; to
our illustrator and friend Fabio Rodaro, who,
with wisdom and intuition, has managed to
transform often ultratechnical images into pleasing and original drawings.
A heartfelt thanks goes to our orthodontist
friend Luca Conoscenti, for his valuable collaboration, which has always proved helpful in developing and achieving often ambitious projects; to
Piero Corsi, an irreplaceable friend with whom I
share much of my free time, for his visual ideas
for teaching and the unconditional friendship
that he has always shown toward me.
A particular thank you to my assistants, Silvia Della Ricca, who has actively collaborated
in the realization of this book as assistant photographer, and Daniela Baiutti, with whom
I have shared my entire professional life and
growth, for her help and patience.
Luca Pascoletti
Pasquale Loiacono
Part One
Theory
16
Chapter 1
General Principles
of Photography
17
Photography in Dentistry
magnification factor is a multiplicative factor.
Each multiple of the focal length corresponds to
a multiple of the magnification factor.
If the focal length is multiplied by four, the
resulting magnification factor is 4×. Similarly,
when the focal length is reduced by half, the
magnification factor is 0.5×, creating an image
half the size of natural vision. To summarize,
reducing the focal length results in an increase
in the perceived angle of the field of view
and a decrease in the magnification factor.
An increase in the focal length results in a
decrease in the angle of view and an increase
in the magnification factor, or size of the
object perceived by the observer (Table 2-1). In
this instance, there will be a cropping effect
so that a smaller portion of the subject will be
included in the photograph, and it will appear
magnified (Fig 2-10). The prismatic magnifying
system commonly used in clinical practice has
a magnification factor of 4.3×, meaning that the
practitioner’s vision of the scene is magnified
4.3 times with respect to normal vision.
Fig 2-10
A summary of the correlation between focal length and angle of view: as the focal length increases, there is a corresponding
decrease in the perceived angle of view and an increase in the magnification factor.
54
The Optical System
Relationship between focal length, angle of view, and magnification factor
As the focal length increases
Angle of view decreases
Magnification factor increases;
Image of object is magnified
As the focal length decreases Angle of view increases
Magnification factor decreases;
Image of object is reduced
Table 2-1
Fig 2-11
Fig 2-11 The characteristics of a lens are
inscribed on the lens itself: 28 mm indicates
the focal length; 1:2.8 indicates the lens
speed, or maximum aperture; ø 49 mm
refers to the diameter of filters or ring
accessories that can be attached if required;
and the words “wide angle” describe the
type of lens. Because the focal length is
28 mm and the lens speed is f/2.8, the
maximum aperture is 10 mm (28:10 = 2.8).
“MC” indicates that this is a macro lens
with a short minimum focusing distance.
Fig 2-12
The Yashica Dental Eye camera uses a
classic 24 × 36–mm film format. Next
to the camera is the additional 2× lens
required to increase the magnification
factor. The additional lens is a focal
multiplier. The direct relationship between
focal length and magnification ratio is
clearly evident.
55
Photography in Dentistry
Exposure may also need to be corrected in the
presence of metallic accessories such as rubber
dam clamps or base supports for shade guides.
These can cause reflections that can deceive
the exposure meter, resulting in an extremely
underexposed image. Even objects placed onto
a black or dark background can deceive the
exposure meter, resulting in an overexposed
image. This is common when photographing
prostheses or orthodontic appliances.
Every camera is fitted with an exposure
correction button that allows the operator
to achieve excellent results by means of
rapid consecutive adjustments (Figs 3-5a to
3-5c). There is a similar button for the flash,
giving the operator two methods to correct
the exposure (Figs 3-5d and 3-5e). The result
of using either button is the same, because
they both affect the duration of the flash as
determined by the camera–exposure meter
synergy.
Fig 3-4a
Fig 3-4b
The exposure can be corrected after recording
the image by means of special programs at the
processing or postproduction stage. However,
a photograph should be excellent at the stage
of image acquisition; it is unacceptable to
manipulate an image to make it appear
suitable for a particular purpose, even if
software allows it. The basic aim is to faithfully
document reality, not to manipulate it to
make it appear better than it is. It is neither
ethical nor scientifically correct to manipulate
images beyond slight corrections of exposure,
contrast, or color; minor modifications, such
as slight cropping or rotating of the image, are
admissible to correct the magnification ratio
or the orientation of the image.
Fig 3-4c
Figs 3-4a to 3-4c
A tooth is photographed against three different backgrounds, with no exposure correction. The tooth against the white
background appears less bright, while the white background itself looks gray. Against the black background, the tooth
appears much whiter and more luminous than in the other images, and it appears more natural in its brightness against
the gray background. The exposure meter has interpreted the white background as standard gray, and the camera has
greatly underexposed the image. The opposite has occurred against the black background, resulting in overexposure. The
different brightness or value of the tooth is the primary parameter perceived by the human eye, much more so than the
difference in color of the tooth. This is a fundamental concept in esthetic restorations. This series of photos effectively
demonstrates the physiological phenomenon of simultaneous value contrast.
82
The Concept of Exposure
Fig 3-4d
Fig 3-4e
Fig 3-4f
Figs 3-4d to 3-4f
The series of three photographs is repeated with an exposure correction of + 1 exposure value (EV). Against the white
background, the tooth is represented more realistically, but against the black background, overexposure has created a
decidedly poorer-quality image.
Fig 3-4g
Fig 3-4h
Fig 3-4i
Figs 3-4g to 3-4i
The series of three photographs is repeated with an exposure correction of -1 EV. Against the white background, the image of
the tooth is poorly lit, but the image is much better exposed against the black background. Different exposure settings result in
considerable variation in the perception of the brightness of the tooth. A simple photograph is not a reliable method to transmit
information relating to the brightness of the tooth. To convey the value of the tooth more effectively, it should be photographed with
appropriate exposure corrections alongside an object of known brightness to which it can be compared, such as a shade guide.
Fig 3-4j
Fig 3-4k
Fig 3-4l
Figs 3-4j to 3-4l
This series of photographs shows the influence of background brightness on the exposure. To convey the correct brightness
of the tooth itself against different backgrounds, the following corrections were made: +1 EV against the white background,
-1 EV against the black, and no change in EV against the mid-tone gray. The perceived differences in brightness depend on
the physiological phenomenon of value contrast.
83
Photography in Dentistry
[
By the term frame, we mean the area of space included and visualized in the photographic
image. What makes up the frame is the choice of the magnification ratio, which is the mere
expression of the photographer’s will.
Concept of Framing
The frame is the area of space included and visible
in the photographic image. As previously
discussed, the magnification ratio is the means
used to distinguish elements that are important
to include in the image from those that must be
excluded.
To repeat the one essential rule that
underlies the reasoning and methods of closeup dental photography, the two priorities are
magnification ratio and depth of field.
A corollary of this general rule is that the
choice of the magnification ratio determines the frame.
Related to this rule are two problems particular
to dentistry. First, the practitioner needs to
use soft tissue retractors and specially shaped
mirrors for many types of images, especially for
posterior and occlusal views. Second, the center
of the frame often does not coincide with the
desired focal point. There is often a difference
between the point at which the camera is
aimed and the point to be put into focus. The
tasks of framing and shooting are facilitated
when these two points coincide. When these
points differ, additional effort and thought are
required to obtain an excellent documentary
photograph.
164
[
Accessories for Intraoral Photography:
Retractors and Mirrors
All intraoral images require the use of
accessories to retract the soft tissues and allow
correct framing with respect to the desired
magnification ratio. Moreover, they remove
unwanted peripheral elements or elements of
visual tension. Cheek retractors are made of
plastic or metal, in various shapes and sizes, and
are chosen according to the image to be taken
(Figs 7-1a and 7-1b). Some photographs require
the aid of mirrors, which are also available in
a variety of shapes to reflect the targeted area
(Figs 7-1c and 7-1d). Without the aid of these
devices, it is impossible to directly photograph
the complete arch from the occlusal aspect,
because to do so would exceed the anatomical
limitations of the patient’s mouth opening
(Fig 7-2a). Similarly, it is not possible to take a
lateral view without a mirror, because the cheek
requires complete retraction (Fig 7-2b). The
accessories recommended for various images
will be illustrated.
The Orthography of Images
Fig 7-1a
Fig 7-1b
Fig 7-1c
Fig 7-1d
Figs 7-1a to 7-1dc
Mirrors and cheek retractors are available in various shapes and sizes for different kinds of images and patients.
Fig 7-2a
An occlusal photograph of the entire arch requires the
use of appropriate mirrors. This image cannot be framed
directly because of the anatomical limitations of the
patient’s mouth opening.
Fig 7-2b
The presence of perioral tissues prevents the practitioner
from taking certain shots directly. In this lateral
photograph of arches in occlusion, the use of appropriately
shaped mirrors is necessary to photograph a reflected,
rather than direct, image. The image will not be real, but
instead will be reflected and inverted; with appropriate
programs for handling the image, it is easy to invert the
image again and render it true to life.
165
Photography in Dentistry
View 9
Degree of difficulty: 5
Position of the patient:
⦁ Backrest of the treatment chair inclined 135 degrees (Fig 12-21a)
⦁ Head turned 70 degrees towards the practitioner
Fig 12-21a
Position of the assistant:
⦁ Seated at the 12-o’clock position (Figs 12-21a and 12-21b)
⦁ Cheek retractor held in the left hand; mirror in the right hand
Position of the practitioner:
⦁ Standing at the 7-o’clock position (Figs 12-21a and 12-21b)
Camera settings:
⦁ Camera held horizontally 45cm from the focal point
⦁ Magnification ratio 1:2.7; aperture f/32 (minimum aperture)
⦁ Flash units placed side by side at the 9-o’clock position (Fig 12-21c)
⦁ Aiming point and focal point on the maxillary right first premolar
(Fig 12-21d)
Fig 12-21b
Type of cheek retractor:
⦁ Handheld cheek retractor
Fig 12-21c
Type of mirror:
⦁ Bean-shaped mirror; tapered end used
Fig 12-21d
Accessories Needed
262
Fig 12-22a
Fig 12-22b
Fig 12-22c
Fig 12-22d
Fig 12-22a Saliva ejector and air-water spray.
Fig 12-22b Handheld cheek retractor.
Fig 12-22c Bean-shaped mirror.
Fig 12-22d External-handle mirror (Omnia) for
lateral views.
Fig 12-22e The correct position of the mirror is
shown; the concave-convex edge of the tapered
end is positioned above, with the convex one
below.
Fig 12-22e
Intraoral Series
Right Quadrants in Occlusion
Comments
Fig 12-23
This image of the right quadrants in normal occlusion, from the central incisor to the second
molar, is suitable for orthodontic documentation.
The difficulty of this shot is that it is
extremely hard, or even impossible, to view
the teeth in occlusion as far back as the
second molar while remaining perpendicular
to the arches themselves; this shot often
has an angulated perspective.
In this procedure, the assistant retracts
the lips on the contralateral side using
the retractor without excessive force. The
drop-shaped end of the bean-shaped
mirror is held in the right hand and inserted
horizontally into the mouth until the tip
reaches the distal of the second molar.
At this point, the patient is asked to open
widely, and the assistant pushes the
mirror towards the cheek while rotating
it 90 degrees, bringing the convex edge
towards the upper vestibule. The patient
is then asked to gently close the teeth
without contracting the masseter muscle;
this enables the assistant to bring the tip
of the mirror, which at this point is distal
to the second molars, outwards towards
the cheek. This procedure creates the
maximum possible space between the teeth
and mirror. If the inclination of the mirror is
50 degrees away from plane of the facial
surfaces of the teeth, the photograph will
conform to the zero-coordinate rule.
The assistant holds the mirror firmly without
obstructing the light from the flash units,
which should reflect onto the mirror to
illuminate the entire frame. The practitioner
should make an effort to keep the teeth dry
with the saliva ejector and the air-water
spray, asking the patient to move the tongue
as far as possible from the teeth, towards
the back of the throat.
Fig 12-24b
Fig 12-24a
The correct position of accessories and proper The correct position of the practitioner and
the flash units.
grasp of instruments.
Alternative Method
Fig 12-2ga
Because this shot requires the
assistant to apply a great deal of
strength, a mirror with an external
handle can be used.
Fig 12-25b
The correct position of the
practitioner and the patient, whose
head must be correctly rotated.
Fig 12-25a
Fig 12-25b
263
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