The Correlation of DIFOTI to Clinical and Radiographic Images in Class II Carious Lesions
Mohammed Bin-Shuwaish, BDS, MS,
Peter Yaman, DDS, MS,
Joseph Dennison, DDS, MS and
Gisele Neiva, DDS, MS
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ABSTRACT
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Background. The authors conducted a study to evaluate the correlation between digital imaging fiber-optic transillumination (DIFOTI) (KaVo Dental, Lake Zurich, Ill.) and clinical and radiographic images in estimating the true clinical axial extension of Class II carious lesions.
Methods. The authors examined 51 Class II carious lesions visually, imaged them by means of DIFOTI and radiographed them with D-speed film and a complementary metal oxide silicon (CMOS)–based digital radiographic sensor. They validated axial extension of the lesions clinically. They compared the clinical and radiographic depths of the carious lesion with the size of the lesion on the DIFOTI images.
Results. The authors detected 84 percent of the lesions with DIFOTI, and 82 percent showed a visible dark shadow under the marginal ridge when examined clinically. DIFOTI correlated significantly with the clinical depth of decay (Pearson r = 0.43189). The combination of a CMOS digital sensor and DIFOTI (R2 = 0.7210) provided readings closer to the clinical measures than did the combination of D-speed film and DIFOTI (R2 = 0.6215).
Conclusions. DIFOTI images correlated with clinical depth, especially in smaller lesions, and improved the estimation of lesion size when used in conjunction with the CMOS digital sensor and D-speed images.
Clinical Implications. Using radiographs in combination with DIFOTI images could help clinicians determine the presence and, to some extent, the size of proximal caries, especially in smaller lesions.
Key Words: Caries; carious lesions; radiographic film; radiography, digital; risk assessment; technologyAbbreviations: CMOS: Complementary metal oxide silicon • DEJ: Dentinoenamel junction • DIFOTI: Digital imaging fiber-optic transillumination • FOTI: Fiber-optic transillumination
Different diagnostic tools are used to arrive at a more accurate and reliable diagnosis for proximal carious lesions. Among these are bitewing radiographs (conventional and digital), fiber-optic transillumination (FOTI) and digital imaging fiber-optic transillumination (DIFOTI [KaVo Dental, Lake Zurich, Ill.]). Because the D-speed (Kodak Ultra-speed, Kodak Dental Systems, Rochester, N.Y.) film group has a high degree of inherent contrast and therefore leads to better detection of carious lesions, many researchers have used this film as a standard for comparison of the caries-detection capabilities of most of the subsequently produced films (E-speed, E-speed Plus and F-speed films, all manufactured by Kodak Dental Systems) and digital technology.
With the rapid development in digital technology, digital radiographic systems have come into more common use by dental practitioners in recent years. Results of most of the in vitro studies in which different digital radiographic systems have been compared with conventional films indicate that radiographs lead to underestimation of the true extent of interproximal carious lesions.1–6
Illuminating teeth to determine the presence of demineralization or caries is a novel method of detecting and monitoring dental caries that may improve the accuracy of caries detection. The DIFOTI system has made this technology accessible for dental practitioners. The principle behind transilluminating teeth is that demineralized areas of enamel or dentin scatter light (in this case a high-intensity white light) more than do sound areas.7 DIFOTI technology involves light, a charge-coupled device camera and computer-controlled image acquisition. The advantages of DIFOTI over radiography include the absence of ionizing radiation, the lack of a need for film, real-time diagnosis and higher sensitivity in detection of early lesions not apparent in conventional radiography, as has been demonstrated in vitro.8 In the DIFOTI image, carious lesions are apparent as a black area within the tooth because of the difference in light refraction between healthy and demineralized tissues.9
The principle behind transilluminating teeth is that demineralized areas of enamel or dentin scatter light more than do sound areas.
Investigators in a 2005 in vitro study10 compared the interproximal caries depth in images taken with DIFOTI and F-speed films with the actual histologic depth of the lesion. They found that DIFOTI was able to help detect surface demineralization at an early stage, but they could not measure the depth of a proximal lesion accurately. We found no clinical studies in which the investigators attempted to measure the in situ depth of Class II carious lesions clinically and correlate the findings with those on digital radiographs, D-speed radiographs and DIFOTI images.
In this study, we used an in situ validation method for determining the true clinical extension of proximal carious lesions by means of direct visual observation of the lesion’s deepest extent. Our objective was to compare the clinical measurements with the estimated axial caries depth from the D-speed film, the RVG 6000 sensor ([Kodak Dental Systems]) and the DIFOTI examinations.
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SUBJECTS, MATERIALS AND METHODS
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The subjects of this study were patients in the Graduate General Dentistry Clinic at the School of Dentistry, University of Michigan, Ann Arbor, whose prospective treatment (as planned by attending faculty members [P.Y., G.N., J.D.]) involved Class II restorations. Fifty-one Class II carious lesions (in 33 premolars and 18 molars) in 21 subjects (15 women and six men) ranging in age from 20 to 54 years were included. We obtained approval for the study from the University of Michigan Health Sciences Institutional Review Board, Ann Arbor. Each tooth included in the study had at least one new interproximal lesion that extended to or beyond the dentinoenamel junction (DEJ) and was in proximal contact with an adjacent tooth. We excluded teeth with frank cavitation, severe rotation or clear signs or symptoms of pulpal inflammation.
Before obtaining any radiographs, the primary investigator (M.B-S.) bonded a measurement device (a 3-millimeter segment sectioned from the tip of a marked periodontal probe) to the occlusal surface of the decayed tooth to act as a reference instrument. He then obtained one radiograph, using size 2 D-speed double-pack film (Kodak Dental Systems) exposed with a radiographic unit (GX-770, Gendex, Des Plaines, Ill.) according to the manufacturer’s guidelines (70 kilovolt peak, 7 milliamperes, 25 pulses). The unit has an 8-inch round cone that was placed in contact with the ring of the film-holding system (RINN XCP, Dentsply, York, Pa.), which in turn was placed in contact with the patient’s cheek during exposure.
The primary investigator then made a digital image of the same tooth by exposing the RVG 6000 size 2 digital sensor (Super CMOS sensor, Kodak Dental Systems) with the same radiographic unit according to the manufacturer’s guidelines (70 kVp, 7 mA, 10 pulses) using the RINN XCP-DS positioner (Dentsply, York, Pa.). He exposed all radiographic images and films, using the same radiographic unit for all images. A trained dental assistant developed conventional films in an automatic roller-type processor (Gendex GXP, Gendex) with self-replenishing solutions (Supermax GX solutions, Gendex), and the digital radiographs were saved directly to the electronic patient record.
Visual and DIFOTI examinations.
The primary investigator first cleaned the selected tooth by using prophylaxis paste and a rubber cup, then dental floss. The appearance of a dark shadow or opaque halo under the enamel of the marginal ridge or in the area of the proximal contact was considered indicative of caries. He recorded findings from the visual examination on the patient data form as "halo present" or "halo absent." He performed the DIFOTI examination after the visual examination, having turned off the dental operatory light. He used the DIFOTI system according to the manufacturer’s instructions (Figure 1
), mounting the proximal mouthpiece on the handpiece and then placing the mouthpiece over the tooth with the proximal lesion. This allowed light to shine from the buccal surface in the proximal contact, through the tooth, to be captured on the lingual surface. He then obtained a second image from the lingual surface. The image appeared in real time on the computer monitor, and the investigator saved it in the electronic patient record.
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Figure 1. The digital fiber-optic transillumination (DIFOTI) (KaVo Dental, Lake Zurich, Ill.) working mechanism.
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Operative technique.
The investigator established the true clinical extent of the proximal carious lesion by making measurements from photographs obtained serially during the operative procedure. He performed all of the restorative treatments and used a dental local anesthetic agent for all treatments.
The investigator obtained a preoperative photograph with a digital camera (Nikon D70 SLR, Nikon, Tokyo). He isolated the teeth with a rubber dam, then accessed the lesion by using a suitable carbide bur and carefully dissected it in a stepwise manner cervically through the carious tissue. He obtained a series of occlusal intraoral photographs in an attempt to capture the cross-sectional views of the lesions at their deepest points. Before obtaining each photograph, the investigator placed in the operative field the same measurement device he had used during radiography to serve as a reference instrument. He repeated the photographic sequence at approximately 1-mm intervals until the maximum depth of the caries was exposed. He then prepared and restored the tooth with a suitable restorative material of the patient’s choice according to standard clinical procedures.
Each radiograph was scored by two clinicians (P.Y. and J.D.), each of whom had more than 25 years of clinical teaching and private practice experience. They used a subset of five radiographic sets from the 51 lesions to calibrate and standardize their radiographic scoring procedure. Seven days after the calibration exercise, both examiners scored the radiographic sets independently and created the final radiographic score by means of consensus. The examiners were blinded to the corresponding clinical data for each lesion.
The examiners used a standard fluorescent dental viewing box (8 x 10 inches) to examine the D-speed films, with all areas peripheral to the radiographic mounts blocked out to minimize the glare. They measured the RVG 6000 images directly from a 19-inch computer monitor (Dell UltraSharp 1905FP, Dell, Round Rock, Texas) with the RVG 6000 image being enhanced automatically (x 7 magnification). Using a clear plastic ruler, they measured the distance between the centers of the notches of the reference device in each radiograph and recorded it to the nearest 0.5 mm. Next, they measured the carious lesion in terms of its axial extension from the DEJ on the selected radiograph. Once they recorded the second value, they calculated the radiographic value of the lesion depth by dividing the measured value of the lesion by the measured value of the reference device.
The two clinicians viewed and scored the DIFOTI images at the same computer screen after discussing each case to attain consensus. They determined the extent of the lesion according to the size of the black area on the image and scored each lesion as 0, lesion not present; 1, small lesion present; 2, medium lesion present; or 3, large lesion present.
The primary investigator measured the true clinical depth of the carious lesion as shown in the photographic images. He examined the images at varying depths carefully to identify the photograph that depicted the lesion at its deepest point in the axial direction. He performed the selection of the photographic images twice, five days apart, and in every case selected the same image both times, so this procedure can be considered reliable. The selected images had a dimension of 2,000 x 3,000 pixels and a resolution of 300 dots per inch. He measured the lesions and the reference device directly from the computer monitor by applying the same procedure used with the radiographs. He measured the deepest axial boundary of the carious lesion from the DEJ, as evidenced by visual changes in dentin. He obtained the actual clinical value of the lesion depth by dividing the measured value of the lesion by the measured value of the reference device. To avoid recall bias, he made two measurements five days apart and used the average of the two measurements as the final measured value.
One of the authors (G.N.) analyzed correlations of the clinical and radiographic results with the DIFOTI images by using commercially available software (SAS 9.1.2, SAS Institute, Cary, N.C.).
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RESULTS
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We calculated sensitivity and specificity values for the clinical examination modalities (visual and DIFOTI examinations) at two clinical levels. The first level, which was determined from the clinical measurements, was lesions extending into dentin. There were no true-negative or false-positive values, so specificity could not be calculated at that level (Table 1).
The second level was cavitation of the proximal surface (Table 2). The primary investigator validated the status of the proximal surface clinically during the operative procedure and noted in the patient’s data form the presence or absence of a visible dark shadow under the marginal ridge of the affected tooth. Eighty-two percent of the lesions (42 of 51) had a visible dark shadow under the marginal ridge. Figures 2, 3 and 4 show examples of small, medium and large lesions, respectively, on DIFOTI images with the corresponding radiographs. Table 3 (page 1379) shows the distribution of the clinical depth measurements in relation to the scores for visible dark shadows. Seventy-six percent (32 of 42) of the lesions with a visible dark shadow showed clinical caries extension ranging from 0.6 to 2.0 mm into dentin. Forty-three lesions appeared as small, medium or large lesions on the digital images captured by DIFOTI imaging (Table 4, page 1379). Eighty-one percent (35 of 43) of the lesions detected with the DIFOTI had a visible dark shadow under the marginal ridge. The 18 small lesions revealed by DIFOTI had clinical depth measurements that ranged from 0.1 to 1.5 mm, and 94 percent (17 of 18) of the medium-sized lesions had clinical depth measurements that ranged from 0.6 to 1.5 mm.
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Figure 2. Images of a lesion that was scored as "small." The lesion is on the distal aspect of the maxillary left second premolar. A. Radiographic image. B. Digital fiber-optic transillumination image.
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Figure 3. Images of a lesion that was scored as "medium." The lesion is on the distal aspect of the maxillary right second premolar. A. Radiographic image. B. Digital fiber-optic transillumination image.
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Figure 4. Images of lesions that were scored as "large." The lesions are on the distal aspect of the maxillary right first molar and the mesial aspect of the maxillary right second molar. A. Radiographic image. B. Digital fiber-optic transillumination image.
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TABLE 3 Distribution of scores for visible dark shadows under the marginal ridge in relation to the clinical depth measurements.
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Table 5 presents a comparison of the results achieved with the different examination modalities. It also shows the average and the range of the clinical lesion depth. Only one lesion was not detected by either of the two examination modalities, whereas 35 lesions were detected by both of them.
We generated two scatter-plots (Figures 5 and 6, page 1380) to evaluate whether DIFOTI, when used in conjunction with either of the imaging methods, could be used to clarify some of the variation observed with smaller lesions. By looking at the DIFOTI scores in both plots, we noticed that smaller scores (representing smaller lesions) tend to be concentrated where the scatter is the greatest. Therefore, we can say that DIFOTI may help in the diagnosis of smaller lesions when used in conjunction with one of the two tested radiographic methods.
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Figure 5. Scatterplot for the clinical depth of caries against caries depth captured by D-speed radiographs. Numbers represent digital fiber-optic transillumination image scores (0 = no lesion, 1 = small lesion, 2 = medium lesion, 3 = large lesion). The line represents the area in which the lesion is given the same depth score clinically and radiographically. Smaller scores (representing smaller lesions) tend to be concentrated where the scatter is the greatest. mm: Millimeters.
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Figure 6. Scatterplot for the clinical caries depth as assessed against caries depth captured by means of a complementary metal oxide silicon (CMOS) digital radiographic sensor. Numbers represent digital fiber-optic transillumination image scores (0 = no lesion, 1 = small lesion, 2 = medium lesion, 3 = large lesion). The line represents the area in which the lesion is given the same depth score clinically and radiographically. Smaller scores (representing smaller lesions) tend to be concentrated where the scatter is the greatest. mm: Millimeters.
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We used simple linear regression analysis to confirm the results from the scatterplots. The combination of RVG 6000 and DIFOTI (R2 = 0.7210) provided readings closer to true clinical measures than did the combination of D-speed film and DIFOTI (R2 = 0.6215). The depth of the lesion captured with both the RVG 6000 and DIFOTI combination and the D-speed film and DIFOTI combination did increase with the true clinical depth (P < .001), but the relationship was stronger with the RVG 6000 and DIFOTI combination. The use of DIFOTI led to significantly improved estimation of lesion size when used in conjunction with D-speed films (P = .004) and RVG 6000 images (P = .003). Therefore, we concluded that use of DIFOTI in conjunction with either the RVG 6000 digital radiographs or the D-speed radiographs improves the diagnostic accuracy of these methods.
We used Pearson r to confirm the results of the regression analysis. Clinical depth of decay was correlated more highly with RVG 6000 images (Pearson r = 0.81303) than with D-speed film (Pearson r = 0.74090). DIFOTI correlated with the true clinical depth of caries, but to a lesser extent than did the radiographs; however, this correlation still was significant (Pearson r = 0.43189). Even though DIFOTI readings were poorly correlated with RVG 6000 images (Pearson r = 0.23866) and D-speed (Pearson r = 0.22893) images, the two scatterplots show that DIFOTI may be more useful in diagnosing smaller lesions when used in conjunction with either radiographic method.
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DISCUSSION
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New diagnostic devices such as DIFOTI have been introduced to improve early detection of carious surfaces.10 Few studies have been conducted to correlate DIFOTI with different diagnostic tools. Our objective in this study was to compare the findings of the two radiographic examinations with the results of the DIFOTI examination and to correlate that result with the true clinical findings. The results showed that the DIFOTI detected 84 percent (43 of 51) of the lesions, yielding a sensitivity of 0.84 for detecting dentinal lesions (Table 1
). In vitro, Schneiderman and colleagues8 found that the sensitivity for detecting proximal caries in 50 mounted extracted teeth with DIFOTI was 0.69 and the specificity was 0.73.
In this study, all 51 lesions penetrated into dentin, so the specificity could not be calculated. Because of the difficulty in measuring the caries extension on the DIFOTI images, we used a categorical scale to describe the size of the lesion.
Comparing a continuous rating scale (such as the one we used to rate the caries extension in the radiographs and clinical images) with a categorical scale (such as the one we used to describe the lesion size in the DIFOTI images) may not yield much information. Results from this study showed that 72 percent (13 of 18) of the lesions with a small shadow had a clinical depth ranging from 0.1 to 0.6 mm, 72 percent (13 of 18) of the lesions with a medium shadow had a clinical depth ranging from 0.6 to 1.2 mm and only 29 percent (two of seven) of the lesions with a large shadow had a clinical depth ranging from 1.4 to 2.0 mm. These results indicate that DIFOTI may be more accurate in the prediction of small lesions. The correlation between the DIFOTI images and the radiographs becomes stronger with small lesions. Statistical analysis showed that DIFOTI led to significant improvement in the accurate estimation of lesion size clinically when used in conjunction with D-speed (P = .004) or RVG 6000 (P = .002) radiographs, and the depth of the lesion captured by the DIFOTI imaging, along with either type of radiography, significantly increases with the increase in true caries depth (P < .001).
One of the limitations of this study was the possibility of errors in capturing or reading the images because of the investigators’ inexperience in using and interpreting DIFOTI imagery. It is important to understand the limitations of the DIFOTI device when one is comparing a DIFOTI image with a radiograph to diagnose a proximal carious lesion. DIFOTI captures only the light emerging from the tooth surface that is closest to the digital camera, whereas the radiographic beam penetrates through the entire tooth and adjacent structures to show any changes in the tooth’s density or structure. The manufacturer of DIFOTI specified that it is to be used for detecting carious lesions, not for determining the depth to which caries extends. Therefore, DIFOTI does not replace bitewing radiographs, but instead serves as an adjunctive diagnostic tool.
The results of this study showed that the percentage of the visually detected dark shadows under the marginal ridges increases with clinical depth. All lesions penetrating 1.1 to 2.0 mm into dentin were detected visually (Table 3). This information implies that visual examination has a high sensitivity in detecting lesions that penetrate deep into dentin.
Eighty-two percent (42 of 51) of the lesions had visible dark shadows under the marginal ridges, with clinical caries extension ranging from 0.1 to 2.0 mm into dentin. Visual examination showed high sensitivity in detecting cavitated lesions (1.0). However, the specificity of the visual examination for cavitation was low (0.27) but still higher than that of DIFOTI (0.15). Only one lesion with a clinical depth of 0.1 mm was not detected by either of the two intraoral examination modalities. We detected 69 percent (35 of 51) of the lesions with both visual and DIFOTI examinations.
The results of this study proved the effectiveness of combining intraoral examination modalities to detect interproximal carious lesions. Therefore, using the diagnostic results of DIFOTI and visual examinations in conjunction with radiographs can aid the clinician in diagnosing lesions for restorative treatment.
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CONCLUSION
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Within the limitations of this study, we can reach the following conclusions:
- – DIFOTI correlated significantly with clinical caries depth, but to a lesser extent than did radiographs (D-speed and RVG 6000), and this correlation tended to be better with smaller lesions.
- – DIFOTI significantly improved the estimation of lesion size when used in conjunction with RVG 6000 and D-speed radiographic images.
- – The sensitivity of DIFOTI in the detection of the cavitated lesions was 0.83. Therefore, DIFOTI could be considered a useful adjunct to clinical and radiographic examinations in detecting inter-proximal carious lesions.
- – Visual examination has high sensitivity in detecting lesions that penetrate deep into dentin. All lesions penetrating 1.1 to 2.0 mm into dentin were detected visually.
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FOOTNOTES
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Dr. Bin-Shuwaish is an assistant professor, Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Saudi Arabia.
Dr. Yaman is a clinical professor and the director, Graduate Restorative Dentistry Program, Department of Cariology, Restorative Sciences and Endodontics, School of Dentistry, University of Michigan, 1011 N. University, Ann Arbor, Mich. 48109-1078, e-mail "pyam{at}umich.edu". Address reprint requests to Dr. Yaman.
Dr. Dennison is the Marcus L. Ward Professor, Department of Cariology, Restorative Sciences and Endodontics, University of Michigan, Ann Arbor.
Dr. Neiva is a clinical assistant professor, Department of Cariology, Restorative Sciences and Endodontics, University of Michigan, Ann Arbor.
Disclosures. The authors received funding for the research described in this article from Delta Dental, Okemos, Mich., and the RVG 6000 digital imaging system from Kodak Dental Systems, Rochester, N.Y. The authors reported no other disclosures.
The authors thank Delta Dental, Okemos, Mich., for sponsoring the research described in this article. They also thank Kodak Dental Systems, Rochester, N.Y., for providing them with the RVG 6000 digital imaging system.
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[Abstract]
[Full Text]
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ABSTRACT
SUBJECTS, MATERIALS AND METHODS
