Clinical Research Associates

INTRAORAL VIDEO CAMERAS-STATUS REPORT 2006

The following information supplements the August 2006 CRA Newsletter

Relative size of camera handpieces (front & back views)

Click on image to enlarge

Patient Education is the primary application of IO cameras. Traditional educational methods are augmented when patient can see what is being described. Auxiliaries should perform video exam during diagnostic portion of visit & educate patient so they are prepared to decide on treatment options. The IO camera can foster trust & confidence & should not be used merely to sell a treatment plan. Prints can be sent with the patient to educate family members or others assisting in treatment decisions.

Documentation is the second most important application. Images of existing conditions, techniques, treatment outcomes, & changes over time serve as educational tools, legal records, evidence for 3rd party payment, etc. Images of problems not evident in radiographs can be particularly useful, including cracks, broken down teeth, old restorations, caries, periodontal disease, & oral lesions.

Augmentation of vision can be useful in some cases where direct vision is difficult or more magnification is desired, including interproximal areas, distal areas in posterior, crown margins, endodontic therapy, surgical procedures, etc.

Replacement of direct vision has not yet been fully realized. Operating while viewing an on-screen video image is possible, but challenges continue to be difficulty with depth perception & orientation, keeping the lens clear, & access of the video camera in the same place the dental instrument needs to be.

LED illumination: White LEDs (light emitting diodes) are replacing tungsten halogen bulbs. LEDs are smaller, cooler, require less power, & can be mounted directly on the handpiece without the need for fiber optic bundles. These advantages permit camera designs that have light weight, flexible cords, plug directly unto computers & are powered by the USB port, & do not have bulky base stations. In addition, LEDs are more durable than filament bulbs & have a longer rated lifetime. Although LEDs emitted significantly less power than halogen bulbs, CRA's evaluation found no clinical disadvantage. In fact, LEDs often provided more uniform illumination because the lower light level did not create such drastic areas of high brightness & deep shadow. LEDs had a significantly higher color temperature (6,000 K - 12,000 K) than halogen bulbs (3,000 K), but again, the auto-white balance function of the cameras produced acceptable color regardless of the light source.

Digital output: USB & IEEE 1394 (Firewire or iLink) outputs are increasingly common & permit video streaming directly to a computer without requiring a video capture card. Once an operatory is computerized (usually a result of switching to digital radiography), adding an IO camera that plugs right into the computer is a relatively simple & inexpensive upgrade. A more subtle change is that from analog to digital cameras. Newer digital cameras send a digital video signal straight from the camera. Older USB connected cameras still produce an analog video signal that must be converted to USB by a small package of electronics housed in an adapter box or "bulge" in the cord. Both types of cameras produced acceptable image quality in this evaluation. Although digital output greatly simplifies interfacing to computers & electronic storage of images, pixelization of the image continues to be a problem. Live video on the computer was noticeably more pixilated & "jumpy" than the same video stream seen on a video monitor. In this evaluation, S-video continued to produce the highest live video image quality.

On-board memory: Originally, IO cameras required a separate device (video printer) to capture or freeze an image for viewing. Later, image capture was incorporated into the cameras themselves, eliminating the need for a printer. Some early models even used the same electronics borrowed from the printers, permitting the classic single image or quad-split view. Currently, cameras with 12 image memory (Evolution) & 16 image memory (Einstein) are available, each with separate controls for reviewing the images with the patient. The future will see IO cameras with on-board memory similar to digital still cameras. The following photos show a prototype IO camera with built-in SD card slot capable of storing hundreds of images.

Camera provided courtesy of Video Dental Concepts, Inc.

Intraoral Video Cameras VERSUS Digital Still Cameras

Some clinicians have wondered if the now universally accepted digital still cameras have eliminated the need for IO video cameras--No, they have not. Each type of camera has a distinct role in the dental practice.

IO video cameras have faster, easier access for instant viewing & patient education, & are the best choice for rapid viewing within the oral cavity.

Digital still cameras usually have higher image quality & better color & lighting, making them the choice for critical documentation. However, intraoral photography is more tedious, requiring cheek retractors, mirrors, air, air/water syringe & an assistant. Additional time is also needed to transfer & review images on a monitor. Digital still cameras have replaced IO video cameras for extraoral photography, where they produce images with superior resolution, color, & little distortion.

Depth of field is the distance beyond the lens in which objects are in sharp focus. It is a critical parameter for all IO cameras because it affects their intraoral access, field of view, & ease of use.

The following graph illustrates depth of field capability based on the view of stained pits & fissures on an extracted lower first molar. The fixed-focus cameras are listed first, with a single depth range. The variable-focus cameras have three or more depth ranges corresponding to closest-focus setting, one or more intermediate-focus settings, & farthest-focus setting.

Click on graph to enlarge

These data reveal many details about clinical performance:

• The fixed-focus cameras all started 7 mm or more from the tooth, making close-up images in sharp focus impossible; furthermore, this distance limited the transillumination of cracks.
• Beyond 40 mm the fixed-focus cameras lost sharp focus & detail, usually due to loss of light. Consequently, extraoral images were dark & grainy. Fixed-focus cameras are essentially for intraoral photography only.
• The relatively large depth of field of fixed-focus cameras is gained at the cost of distortion. However, sharp focus was always preferred above distortion.
• Variable-focus cameras were able to focus closer to the tooth (<5 mm), providing good close-up & transillumination capabilities.
• At close-focus & intermediate-focus settings, the depth of field was small. This affected three things: 1) Only one limited area was in focus, objects slightly closer or further away were out of focus; 2) Slight movement of the camera sent the object being viewed out of focus, requiring more finesse at positioning & steadying the camera; & 3) Changing position to view a new area often required adjusting the focus, making it more tedious to "fly" around the mouth viewing all areas. Consequently, variable-focus cameras were harder to use & required more training.
• The variable focus control meant any distance from the closest out to essentially infinity could be focused on. Consequently, any view could be brought into sharp focus & intraoral access was improved since wherever the camera was put a useful image could be obtained.
• The variable-focus cameras differed in their depth of field at close & intermediate settings. Those with greater depth at a given setting were clinically easier to use since less adjustment was required.

As the clinical evaluation progressed, & the subtle differences between the cameras emerged, the characteristics revealed by this chart became increasingly clear. Finally we hung a copy on the operatory wall for easy reference during the clinical trials. The clinical performance of a camera can almost be predicted from its depth of field data!

An effort was made to quantify the overall value of each camera by assigning point values to the following characteristics:

• Ease of use
• Image quality
• Intraoral access
• Sheath
• Color
• Close-up capability
• Distortion
• Focus control
• Freeze / capture control
• Retroview
• On-board image memory
• Light control
• Activates when lifted
• Digital output
• Ergonomics / comfort
• Cost
• Disinfection

Out of 83 points possible, the fixed-focus cameras averaged 49.3 points, with a 6 point spread among them. The variable-focus cameras averaged 61.2 points, with a 4 point spread among them.

These results confirmed our clinical evaluation, that all the cameras worked adequately well, were more similar than different, none had all features desired, & that the variable-focus cameras generally had more features than the fixed-focus cameras. Each camera offered distinct advantages & clinicians must choose which characteristics are most important to them. Most of the clinical evaluators were interested in ease of use, image quality, & cost.

Click here to view "Test Protocol for Intraoral Video Cameras."

Copyright © 2006 Clinical Research Associates^®