A Standardized Approach to Extra-Oral and Intra-Oral Digital Photography

Summary

The present protocol describes a method to capture intra- and extra-oral photographs for digital documentation in the clinical practice of dentistry. The protocol highlights all the critical components involved and the commonly utilized settings to capture dental photographs for clinical documentation.

Abstract

Contemporary dentistry mandates a more comprehensive and personalized analysis of each patient. Technological advances in digital photography have played vital roles in diagnostic accuracy, treatment planning, execution of therapies, and outcome evaluations, including esthetic enhancement. Digital photography also provides an excellent platform for patient education, communication, and co-management of cases with other healthcare providers. However, intra-oral photography often faces challenges such as inaccessibility of areas to be captured, different moveable vs. fixed tissues involved, contamination with saliva or blood, and differing illumination needs on various locations. Thus, a more standardized and systematic approach is proposed for intra- and extra-oral documentation via digital photography to overcome the existing technical challenges. The current work will outline the appropriate equipment specifications (camera bodies, macro lens, and flashes), positions and postures of the operator and patients, proper techniques of tissue retraction, the use of appropriate intra-oral mirrors, and the essential elements such as aperture settings (F-stop), ISO, shutter speed, and white balance. This article aims to provide all dental professionals with an approachable linear array of guidelines to produce simplified and standardized visual tools for more efficient and effective documentation.

Introduction

The approach to the clinical practice of dentistry has evolved over the decades to include a conceptual framework of clinical reasoning based on empirical evidence¹. As such, digital documentation now serves as an integral part of the framework on which clinical decisions are made, and evolution of care is observed². The purpose exceeds mere primary legal records and now encompasses a plethora of extensions that include active mode of communication with patients, educational tools for dental members, educators, and colleagues, visual aids for technicians, and finally, effective marketing³.

Dental photography is often mistakenly construed as technically challenging and plagued with hurdles⁴. Clinicians find incorporating dental photography to be laborious, an additive task to an already complex series of events that generally occur during patient consultations or treatment. Capturing the essence of a treatment can be technically daunting, especially when it involves purchasing a series of equipment and assembling them further. Even more, the tandem application of the equipment and initial learning curve has been known to deter clinicians from adopting this modality routinely. Additionally, clinicians who overcome the initial intimidation find themselves wrought with the intricacies of the environment they are capturing. The oral cavity has several movable and fixed components. The different fields of view, tissue hydration levels, range of access limited by the patient range of opening, and different clinical presentations are a few obstacles to mention. When these get coupled together with already existing, established photography equipment, the task of utilizing photography as a tool is not a priority for clinicians⁵. However, with recent advances in technology, clinicians can hugely benefit from adopting dental photography, not merely for educational and clinical decisions, but patient treatment visualization and satisfaction through digital smile design⁶. Incorporating digital records can enhance the planning and execution of complex treatment plans. The standardization of these records allows for direct comparison before and after series, and fosters a digital fingerprint of dental records that captures a patient's clinical footprint in time⁷.

The proposed manuscript aims to standardize the approach to dental photography while illustrating the technical aspects and simplifying the methodology to allow clinicians at different levels to adopt and incorporate photography to increase productivity and achieve success. Furthermore, the manuscript illustrates techniques to practice dental photography without the aid of an assistant, in minimal space with inexpensive equipment and constricted areas.

Camera and supporting infrastructure for enhanced digital photography

Camera
Several different cameras are available for dental photography; however, a digital single-lens reflex (DSLR) or a mirrorless camera is recommended. There are two types of DSLR or mirrorless cameras. A full-frame camera has a sensor size of 36 mm x 24 mm, and a crop-frame 22 mm x 14 mm⁸ (Figure 1A). For dental photography purposes, crop frame sensors are recommended due to the superior depth of view compared to a full-frame camera⁹. Depth of view is the distance between the closest and the furthest point in a picture that noticeably appears clear and focused (Figure 1B). Mobile phone cameras are not recommended for routine dental photography. The cameras lack the necessary settings (aperture) to produce adequate intra-oral photographs. Compact cameras, in general, have a micro 4/3 lens. The lens in these cameras is fixed and not interchangeable¹⁰. Dental photography explicitly demands a macro lens for enhanced image capturing.

Lens
A macro lens has the capability of producing proportional images. The observed 1:1 ratio in the lens context is defined as an image observed by a clinician that is reproduced on the camera sensor and therefore captured in a photograph. Telephoto lenses are zoom lenses; one may get distortions incorporated into an image with zoom¹¹. In a dental photograph, oral structures need to be reproduced as accurately as they appear in the patient's oral cavity, and therefore, macro lenses are well suited for this purpose. Many different macro lenses are available, which differ in focal lengths. A focal length of 85-105 mm is recommended. When acquiring photos, the lens allows one to be in close range with the patient's anatomy without being too close to the patient during photography (Figure 1C).

Flash
There are two kinds of camera flashes available. One is mounted on the camera, and the other is a studio strobe light. For dental photography purposes, the former is recommended¹². Several such systems are available, producing different lighting effects, influencing the quality of photographs obtained. For simplicity purposes, a ring flash is recommended to be mounted onto the camera.

Mirrors
Intra-oral mirrors are an essential tool. They permit the capture of specific segments of the oral cavity that are challenging to capture otherwise. Rhodium-coated mirrors are recommended for their enhanced image quality and physiologically accurate clarity¹³. Alternatively, titanium or steel mirrors set up are employable since they are more durable. However, they do produce images of diminished quality.

Retractors
These are necessary to allow unimpeded access to the oral cavity structures. Rounded-shaped retractors are recommended as they are easy to implement and allow full retraction of extra-oral structures.

Reflector
A photographic reflector is recommended since it helps to illuminate the lower mandibular area in an extra-oral portrait photograph, as the site is commonly influenced by shadows.

Others
Air syringes are commonly used for de-fogging of intra-oral mirrors. A torch is recommended to warm up the mirrors. This ensures that one can capture an image with very little to no help from a second person.

Camera settings and recommendations for intra- and extra-oral photography
To allow complete control of the camera settings (described below), the camera needs to be set at manual mode and single shot (Figure 2D).

ISO
ISO translates to how sensitive a camera sensor is to receiving light (Figure 2A). The higher the ISO, the more sensitive the sensor is to receiving light. This, however, is inversely proportional to the image quality obtained. For dental photography purposes, the recommended ISO needs to be set at 100-400^14,15 (Figure 2B and Table 1).

Shutter speed
Shutter speed refers to how fast a camera shutter responds to enable the sensor to capture an image (Figure 2C,D, and Table 1). The recommended shutter speed needs to be set at 1/125 for intra- and extra-oral photography for dental photography purposes¹⁴.

Aperture/F-stop
F-stop refers to the dimensions of opening by the diaphragm of the macro lens. The lower number corresponds to a wider diaphragm opening, resulting in a shallow depth of view. For dental photography purposes, an aperture of F29-32 is recommended for intra-oral photography and F9-11 for extra-oral photography^14,15 (Figure 2E-G and Table 1).

White balance
White balance is defined as the camera sensor's ability to compensate for color biases influenced by the external light source. For example, an image acquired in the office with yellow light will present warm undertones. The white balance in dental photography needs to be maintained at 5,500 K to obtain physiological representative images¹⁴.

Lighting
Adequate illumination is necessary to acquire physiologically representative images of the oral cavity. The higher the flash ratio (1:1), the stronger the flash output. For dental photography, the illumination on the flash needs to be set at 1:4 or 1:8 ratio since the F-stop is established at 29-32¹⁵.

Picture settings
The picture settings refer to the camera body preset settings for image contrast and saturation. Different settings result in different camera picture styles. Standard or neutral settings are preferred to accurately represent the oral tissues' physiological presentation. Image quality needs to be set at R.A.W. + JPEG fine¹⁶. These settings are used to even out high contrast images by selectively adjusting the highlights and shadows. However, an accurate representation of the patients' oral tissues is desired without artificial modification for dental photography purposes.

Protocol

The protocol involves standardized documentation of patients' clinical presentation as routinely administered at Columbia University College of Dental Medicine, New York. No patient data were utilized for this publication; the co-authors R.B and J.M.D.O are depicted in the photographs themselves, illustrating techniques described in this protocol and providing consent to publish the images involved. Replicating the procedure under clinical settings will require written informed consent from the patients.

1. Acquisition of extra-oral photographs

1. Utilize a ring flash and an extra-oral photography reflector (see Table of Materials) for extra-oral photography.
2. Acquire patient's extra-oral photos with a black background. Use a black velvet cloth for the background to reduce shine or unwanted reflections.
   NOTE: Alternatively, a white background is acceptable as well. It is recommended that the patient be positioned away from external sources of light (i.e., sunlight through a window).
3. Ask the patient to remove the eyewear so that both ears are equally visible.
   NOTE: Individuals with long hair must tuck their hair behind the ear.
4. Position the patient straight across the photographer against the background. Align the patient's head to ensure that the interpupillary line is parallel to the horizontal frame of the camera viewfinder.
   NOTE: The photo needs to compromise the superior portion of the patient's head, and the inferior portion needs to encompass the area just below the thyroid gland (Figure 3A).
5. For standard documentation purposes, position the patient at a 90° angle and capture the straight frontal photo and the right-side profile photos (Figure 3B).
   ​NOTE: Additionally, one may consider adding a left and right photo acquired at a 45° angle for esthetic cases (Figure 3C).
   1. For each position, consider acquiring three poses: repose, natural smile, and widest smile^1,17.

2. Acquisition of intra-oral photographs

1. Ask the patient to sit in a dental chair at a 45° inclined position (Figure 4A). Ensure that the photographer is at the patient's 9 o'clock position with the armamentarium for photography (see Table of Materials) located within arm's reach.
   NOTE: Figure 4B illustrates the viewfinder observed in the cameras. They are employed to center the image captured where the image is centered to the middle of the viewfinder (Figure 4C).
2. Turn off the dental operatory light to prevent light interference with the photos.
3. Acquire frontal photos following the steps below.
   1. Position the patient in maximal inter-cuspal position (M.I.P.)¹⁵.
   2. Place and position the retractors intra-orally into the mouth and recruit the patient to hold the retractors (Figure 4D).
   3. Position the operator such that the plane of occlusion of the camera is parallel to the horizontal frame line in the camera's viewfinder (Figure 4E,F).
      NOTE: Incorrect position of the retractors can result in distorted images where the capture of the soft tissues can be incomplete (Figure 4G). The resultant images do not represent the entire oral cavity when the occlusal plane is not parallel to the operator. Figure 4H,I demonstrates the effect of operator position on the image acquired.
4. Acquire buccal left and right intra-oral photos.
   1. Align the patient's head toward the operator. For acquiring photos on the patient's right side, place the retractor in the left side of the patient's mouth.
      NOTE: The retractor needs to be placed at the angle of the patient's mouth without tension (Figure 5A,C).
   2. Utilize the narrow mirror (see Table of Materials) for the buccal photos. Warm the mirror with a commercially available blow torch before insertion (Figure 5B).
   3. Insert the mirror into the patient's mouth parallel with the occlusal plane, gently move to the left buccal vestibule, and rotate 90°.
      NOTE: The mirror's edge must be rested gently on the external oblique ridge (Figure 5E,F).
   4. Use the mirror to stretch the patient's cheek and, at the same time, reveal a reflection of the buccal surface of the right maxillary and mandibular posterior dentition. Apply the same for the left side.
5. Acquire occlusal intra-oral photographs.
   1. Position the retractor in the patient's mouth. Use the large mirror (see Table of Materials) for capturing this photo.
      NOTE: The patient is recruited to aid in retracting to reveal the maxillary dentition and the buccal vestibule (Figure 6A).
   2. Before insertion, warm the mirror using a Bunsen burner and insert it into the patient's mouth. Request the patient to open the mouth as wide as possible to reveal the entire maxillary dentition from molar to molar in the maxillary (Figure 6B).
   3. For mandibular occlusal photos, change the retractor positions appropriately to reveal the mandibular dentition and associated buccal vestibule (Figure 6D). Request the patient to roll their tongue to the back of the mouth to show the floor of the mouth (Figure 6F). Warm up the occlusal mirror and subsequently insert it gently against the ventral surface of the tongue.
6. Acquire lingual intra-oral photographs.
   1. To view the maxillary palatal sextants¹⁵ (Figure 7A), use the retractor to retract the left or right maxillary lip. Warm up the small mirror, insert it in the patient's mouth, and position it to reveal the palatal surface and the palatal mucosa (Figure 7B).
   2. To view the mandibular palatal sextants¹⁵ (Figure 7C), warm up the small mirror and insert it between the tongue and the lingual surfaces of the mandibular dentition. Gently align the mirror medially to reveal the reflection of the lingual surface of the dentition.

Results

Techniques illustrated in the protocol section were employed to acquire a sequence of extra- and intra-oral photographs. Figure 8A demonstrates the patient in different positions. The three composite positions include repose, natural smile, and widest smile. The photographs are taken in the suggested composite positions to illustrate the facial changes observed in the patient while in function. The musculature surrounding the oral cavity is influenced by restorative work performed in the ora...

Discussion

Traditional evaluation tools in dentistry such as periodontal charting and model impressions of the oral dentition used for generations consistently provide clinical data; however, they have limitations¹⁶. Several clinical pathologies and soft tissue presentations are not accurately represented in traditional modalities of dental evaluation. Thereby, electronic documentation via dental photography is now considered a valuable tool. The clinical photographs reveal the patient's current...

Materials

Name	Company	Catalog Number	Comments
Armamentarium for photography
Buccal Mirror #15- Narrow mirror	Doctoreyes	Ultrabright #15	Width 40 mm with ultrabright coating
Camera	Nikon	D7500
Occlusal Mirror #13- Large Mirror	Doctoreyes	Ultrabright #13	Width 70 mm with ultrabright coating
Ring Flash	YongNu	Macro ring lite YN14EX