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Investigation into use of Digital Imaging Fiber-Optic Trans-illumination (DIFOTI[R]) in caries detection.

Caries is an infectious disease process caused by bacteria. The bacteria involved are primarily Streptococcus mutans and Lactobacillus. (1,2) The process is dynamic, characterized by periods of demineralization and remineralization. (1,3) If demineralization is allowed to continue, the enamel surface will eventually lose its integrity, resulting in a hole formation (cavitation). As Steinberg (4) points out, "Prior to cavitation, the caries process is considered to be reversible."

Caries diagnosis remains a difficult task. In North America, caries is often diagnosed using tactile (often with use of a dental explorer), visual (light and magnification), and radiographic means. The use of an explorer to diagnose caries is not considered to be consistently accurate and may lead to a false positive diagnosis or to the unnecessary destruction of tooth structure. (5) Technological advances such as the DIAGNOdent Caries Detector (KaVo America Corp., Lake Zurich, IL 800/323-8029) have shown promise in the diagnosis of occlusal caries. (1,6) Compared to traditional examination methods for the detection of occlusal caries (use of mirror, explorer, and magnification loupes), DIAGNOdent has been shown to have a higher sensitivity (0.92) than traditional methods (0.82). (6)

Use of the electronic caries monitor (ECM) has also shown some promise for the detection of enamel and dentin caries in occlusal surfaces of posterior teeth. Sensitivity values for ECM regarding the detection of noncavitated occlusal caries have been shown to range from 0.65-0.78. (7) Visual inspection methods for the detection of occlusal enamel caries resulted in a sensitivity of 0.60. Use of bitewing radiographs or fiber-optic trans-illumination have been shown to be inefficient for the diagnosis of occlusal caries. (7)

Dentists routinely rely on bitewing radiographs to help diagnose interproximal caries. Unfortunately, while radiographs do provide information about variations in mineral density, they provide no clue as to whether or not a lesion is cavitated. (8) Also, radiograph imaging exposes patients to ionizing radiation. (9)

Recently, use of Digital Imaging Fiber-Optic Trans-illumination, (DIFOTI[R], registered trademark of Electro-Optical Sciences, Inc., Irvington, NY 800/729-8849) for the diagnosis of interproximal caries has been evaluated and has shown promise in the detection of interproximal, occlusal, and smooth surface carious lesions. DIFOTI has been shown to have a sensitivity value of 0.56 compared to 0.21 for bitewing radiographs when used for the detection of interproximal caries. DIFOTI has also been shown to be three times more sensitive than radiographs for the detection of occlusal caries. (10)

DIFOTI uses a fiber-optic illuminator in a disposable mouthpiece to deliver light to a tooth surface. The light travels through tooth structure and is captured by an electronic charged coupling device (CCD) camera. The camera digitally images the light and projects the image on a computer monitor in real time (Figure 1). Carious tooth structure scatters and absorbs more light than the surrounding healthy tooth structure. Demineralized areas will appear darker compared to the more translucent brighter background of surrounding caries-free tooth structure.


DIFOTI received FDA approval in 1999. This promising technology has potential to allow a dentist to evaluate demineralization on all tooth surfaces as well as inspect for tooth fractures and defective restorations. (1)

This study was conducted to determine sensitivity and specificity of detecting the presence and extent of interproximal carious lesions using both traditional examination techniques (bitewing radiographs) and DIFOTI on 32 extracted maxillary and mandibular teeth.

Materials And Methods

Extracted human adult teeth were collected from three US Army dental clinics. Teeth were examined for inclusion in the study; any teeth exhibiting gross decay, missing tooth anatomy or large restorations were excluded. Eventually, 32 teeth which showed possible signs of the presence of caries based on visual inspection were selected. Teeth were stored in 5% neutral buffered formalin. The selected teeth were mounted in pairs with interproximal surfaces in contact to simulate the relationship found in the dental arch. Teeth were mounted in medium pink baseplate wax for support and numbered. The wax was melted into a 1-inch cube formed around the paired teeth with only the clinical coronal portion of the teeth visible above the wax. The blocks of teeth were photographed from the buccal side (Figure 2).


The project consisted of four phases. During Phase 1, the visible surfaces of each tooth were cleaned with prophy paste and a rubber cup as recommended prior to use of the DIFOTI system. The DIFOTI system was used to image each set of mounted teeth showing both buccal and lingual views (Figure 3). Each image was identified with appropriate tooth numbers. All DIFOTI images were made by the primary author (Carbone).


Images were saved on CD-ROM for future viewing. After completion of DIFOTI imaging, each block of teeth was radiographed. Exposures were made at 70 kVp (kilovoltage peak) and 7 mA (milliamperage) on Kodak DF58 Ultraspeed periapical film using the Gendex GX 770 Intraoral X-ray System. The source-to-film distance for each radiograph was 21 centimeters. Each pair of specimens was exposed. Films were developed at the same time using the A/T 2000[R] XR film processor (Air Techniques, Inc., Hicksville, NY, 800-247-8324). Each pair of specimen numbers was exposed on film for use later in the assessment phase (Figure 4).


Phase 2 involved five dentists, each of whom was participating in a 1-year Advanced Education in General Dentistry Program and had less than 9 months experience as a practicing dentist. None of the dentists participated in Phase 1 of the study. Prior to participating in Phase 2, each dentist received approximately 2 hours of hands-on familiarization with the DIFOTI equipment. This training was conducted by a sales management consultant who was not a dentist or a trained technical consultant. During Phase 2, each of the five dentists independently assessed the presence, location, and extent of interproximal lesions in the experimental teeth mounted in wax cubes as described previously. The examinations were all performed under identical conditions. The examining dentists evaluated both the mounted teeth and corresponding radiographic and DIFOTI images using the same ambient lighting and light box. Initially they examined mounted tooth blocks and corresponding DIFOTI images. Each tooth block and the corresponding radiographic image were assessed 3 days later. On both occasions, the examiners were asked to record suspected lesions on standardized diagrams in ink, noting the exact location and size using the following arbitrary categories:

1. No caries

2. Caries in enamel only

3. Caries extending to dentino-enamel junction

4. Caries extending just past the dentino-enamel junction

5. Caries well into the dentin (encroaching pulp)

For purposes of determining sensitivity and specificity, categories 1 and 2 were defined as "no caries" and categories 3, 4, and 5 were defined as "yes caries".

During Phase 3 of the study, all experimental teeth were removed from the wax mountings and sent to the US Army Dental Materials Laboratory at Fort Gordon, GA for sectioning. The teeth were sectioned mesiodistally through the suspected carious sites using a Isomet low speed saw (Buehler Ltd., Lake Bluff, IL; 800-283-4537) with a 0.30 mm thick diamond wafering blade (no. 11-4244, Buehler Ltd.).

During Phase 4, each of the 64 sections was viewed using a surgical microscope at 15x power (model M705-115, Global Surgical Corporation, St. Louis, MO; 800/861-3585). Each buccal and lingual section was evaluated for caries depth and assigned to one of the same five arbitrary categories as used in Phase 2. The sectioned teeth were photographed using a Minolta DiMAGE 5 digital camera (Konica Minolta Photo Imaging, Mahwah, NJ 201/574-4000) mounted on a tripod with a source distance of 25 mm (Figure 5).



As illustrated in the Table, sensitivity ranged from 0.09-0.55 for radiographs and from 0-0.45 for DIFOTI for all examiners. Specificity ranged from 0.86-1.0 for radiographs and from 0.90-1.0 for DIFOTI. Consensus sensitivity and specificity values were determined by three or more examiners agreeing on a caries category.

A comparison of the consensus results for all examiners determined that the sensitivity for DIFOTI was 0.18. Consensus sensitivity for radiographs was determined to be 0.45.

Specificity values were also determined. Experimental results for use of radiographs showed a specificity of 1.0. Experimental use of DIFOTI as a diagnostic tool also resulted in a specificity value of 1.0. The Kruskal-Wallis test was calculated to determine a statistical difference in caries diagnosis between radiographs and DIFOTI. The test showed a significant difference in the diagnosis of caries using radiographs vs. DIFOTI ([rho] = 0.003). The [chi square] test was used to show statistical differences between sensitivity (as represented by categories 1 and 2 [no caries]) and specificity (categories 3, 4, and 5 [yes caries]) data for radiographs and DIFOTI ([rho] = 0.017).

Correlation and regression analysis revealed that the diagnosis of positive caries increased as the depth of the caries increased for both consensus X (radiographs) and consensus D (DIFOTI). The correlation was positive but not strong: consensus X (radiograph) r = 0.62 ([rho] = 0.0002); consensus D (DIFOTI) r = 0.63 ([rho] = 0.0001).


Digital Imaging Fiber-Optic Trans-illumination has been introduced as a diagnostic system for the early detection of caries. The technology allows image formation without the use of ionizing radiation; images can be immediately viewed by both dentist and patient. DIFOTI has shown promise in the detection of interproximal, occlusal, and smooth surface carious lesions. In 1997, Schneiderman et al (10) assessed the use of DIFOTI to diagnose caries on 50 extracted human teeth. In their study, 5 clinicians "experienced in oral diagnosis" were asked to assess radiological images of extracted teeth. Four of the clinicians received 2 hours training in DIFOTI, after which their performance using both technologies (radiographic evaluation and DIFOTI) was scored to determine sensitivity and specificity values. Sensitivity for interproximal surfaces was determined to be 0.56 for DIFOTI and 0.21 for radiographs. Specificity for DIFOTI was 0.76 compared to 0.91 for radiographs.

In 2002, Young (1) reviewed the literature to evaluate caries detection technologies and modern caries treatment methods. In this review DIFOTI was referred to as a "diagnostic instrument for early and reliable detection of caries without the need for ionizing radiation." Young cautioned that clinicians who use DIFOTI (and compare results from radiographic analysis) must understand differences between interpreting radiographs and DIFOTI images. Unlike radiographs in which the "incident beam is transmitted through the entire tooth" resulting in an image which can show the extent of carious lesion penetration into a tooth, DIFOTI images only the light emerging from the surface of the tooth closest to the CCD camera. DIFOTI images surface changes and not necessarily the depth of lesion penetration. It is important to note that the manufacturer of DIFOTI does not claim the device measures the extent of caries penetration.

In this study, 5 relatively inexperienced general dentists (each with less than 9 months of clinical practice experience at the time of the study) received minimal instruction in the use of DIFOTI. Specifically, each dentist was given hands-on familiarization as previously described and then afforded the opportunity to use the equipment in a full mouth survey on one or two subjects. No attempt was made to measure any of the dentist's proficiency with the equipment. Approximately 2 weeks later each of the dentists served as examiners in this study and attempted to diagnose caries in both conventional radiographic images and DIFOTI images. As shown in the Table, one of the examiners, Examiner 3, performed considerably better in diagnosing caries from radiographic images and DIFOTI compared to the other examiners. Experimental sensitivity values for Examiner 3 were 0.55 for radiographs and 0.45 for DIFOTI in comparison to the consensus experimental sensitivity of 0.18 for DIFOTI and 0.45 for radiographs. Our experimental results do not compare well with previously documented experimental results. In a study using five clinicians "experienced in oral diagnosis," Schneiderman et al (10) found DIFOTI to have sensitivity more than twice that of radiography for the diagnosis of interproximal caries. Prior to participating in the study the "experienced" clinicians calibrated their performance against a known standard. The manufacturer of DIFOTI claims a sensitivity value of 0.69 for the diagnosis of interproximal caries.

Clearly the results of the current study may reflect errors due to both the inexperience of the examiners in caries diagnosis and possible inexperience in interpreting DIFOTI images. Both Cortes et al (11) and Lavonius et al (12) report that extensive training with fiber-optic trans-illumination equipment is required to use the method successfully. Young (1) points out that "interproximal lesions can be picked up using DIFOTI only by careful angulation." This suggests that the DIFOTI system may have been more effective in detecting caries if the experiment examiners had been more proficient in manipulating the fiber-optic handpiece to effectively view interproximal tooth structure.

Although the results of this study suggest that our examiners needed more instruction in the efficient use of DIFOTI, the technology has great potential as a powerful patient education tool. The DIFOTI technology can show subtle surface changes associated with potentially demineralized tooth surfaces. Demineralized tooth structure can be documented. Then, after successful treatment designed to remineralize the tooth, the areas can be reviewed again by both the dentist and the patient. The technology also shows promise in evaluating anterior teeth for potentially defective interproximal restorations or early interproximal demineralization, all without the need to expose a patient to ionizing radiation.


1. DIFOTI can be a useful diagnostic adjunct, particularly when used to confirm the absence of disease (specificity).

2. A significant training period is necessary to ensure effective use of this technology. Such training will allow the dentist to properly handle the DIFOTI handpiece to expose all potential carious surfaces and to properly interpret DIFOTI images.

3. The DIFOTI technology may be most useful in identifying demineralized areas of tooth structure and monitoring the results of remineralization therapy.


The authors gratefully acknowledge the rental of a DIFOTI system and the technical support provided by Electro-Optical-Sciences, Inc.


(1.) Young D. New caries detection technologies and modern caries management: merging the strategies. Gen Dent. 2002;50:320-331.

(2.) Anderson MH, Bales DJ, Omnell KA. Modern management of dental caries: the cutting edge is not the dental burr. JADA. 1995;126:727-743.

(3.) Hume W. Need for change in standards of caries diagnosis--perspective based on structure and behavior of the caries lesion. J Dent Educ. 1993;57:439-443.

(4.) Steinberg S. A paradigm shift in the treatment of caries. Gen Dent. 2002;50:333-338.

(5.) Bader JD, Brown JP. Dilemmas in caries diagnosis. JADA. 1993;124:48-50.

(6.) Ouellet A, Hondrum S, Pietz D. Detection of occlusal carious lesions. Gen Dent. 2002;50:346-350.

(7.) Ashley PF, Blinkhorn AS, Davies RM. Occlusal caries diagnosis: an in vitro histological validation of the Electronic Caries Monitor (ECM) and other methods. J Dent. 1998;26:83-88.

(8.) Tan P, Evans R, Morgan M. Caries, bitewings, and treatment decisions. Aust Dent. J 2002;47:138-141.

(9.) Langland OE, Langlais RP. Principles of Dental Imaging. Baltimore: Williams and Wilkins Publishing Co; 1997.

(10.) Schniederman A, Elbaum M, Shultz T, Keem S, Greenebaum M, Driller J. Assessment of dental caries with digital imaging fiber optic transillumination (DIFOTI[R]): in vitro study. Caries Res. 1997;31:103-110.

(11.) Cortes DF, Ellwood RP, Ekstrand KR. An in vitro comparison of a combined foti/visual examination of occlusal caries with other diagnostic methods and the effect of stain on their diagnostic performance. Caries Res. 2003;37:8-16.

(12.) Lavonius E, Kerosuo E, Kallio P, Pietila I, Mjor IA. Occlusal restorative decisions based on visual inspection-calibration and comparison of different methods. Commun Dent Oral Epidemiol. 1997;25:156-159.

MAJ Carbone is a graduate of the Fort Sill Comanche Advanced Education in General Dentistry 12-Month Program (AGD-1) and is currently serving as a dental officer for the 464 Med Co (Dental).

COL Hennessy is the former Assistant Director of the Comanche AGD-1 program and is currently serving as Assistant Director of the Fort Hood Advanced Education in General Dentistry Two Year Program (AGD-2).

COL (Ret) Hondrum is Chief, Dental Materials Laboratory, Fort Gordon, GA.

MAJ Jerry Carbone, DC, USA COL Bernard Hennessy, DC, USA COL (Ret) Steven Hondrum, DC, USA
Sensitivity and Specificity Values from Experimental Examiners

 Examiner 1 Examiner 2

Method X D X D

Sensitivity 0.36 0.27 0.09 0
Specificity 0.86 1.0 1.0 1.0

 Examiner 3 Examiner 4 Examiner 5

Method X D X D X D

Sensitivity 0.55 0.45 0.09 0.18 0.36 0.27
Specificity 0.95 0.90 1.0 1.0 1.0 1.0
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Author:Carbone, Jerry; Hennessy, Bernard; Hondrum, Steven
Publication:U.S. Army Medical Department Journal
Date:Jan 1, 2006
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