Year : 2009 | Volume
: 27 | Issue : 4 | Page : 227--234
Comparison of validity of DIAGNOdent with conventional methods for detection of occlusal caries in primary molars using the histological
gold standard: An in vivo study
A Goel1, HS Chawla2, K Gauba3, A Goyal2,
1 Department of Pedodontics and Preventive Dentistry, D. J. College of Dental Sciences and Research, Modinagar, India
2 Department of Pedodontics and Preventive Dentistry, Oral Health Sciences Center, PGIMER, Chandigarh, India
3 Department of Pedodontics and Preventive Dentistry, Dr. HSJ Institute of Dental Sciences, Punjab University, Chandigarh, India
Flat No. 212, Imperial Block I, Supertech Estate, Sector-9, Vaishali, Ghaziabad - 201 010, Uttar Pradesh
Aim: This study was conducted to compare the in vivo effectiveness of DIAGNOdent with other conventional methods (visual, tactile and bitewing radiographs) for the detection of occlusal caries in primary molars. Another objective of the study was to calculate new cut-off limits for the detection of caries by DIAGNOdent in primary teeth. Materials and Methods: Eighty-four primary molars in 52 children (aged 8-12 years), which were indicated for extraction, were selected and evaluated for dental caries using DIAGNOdent, visual and tactile examination and bitewing radiographs. Histological examination of the sections, prepared subsequent to extraction of the teeth, served as the gold standard for comparison of the above-mentioned methods. Results: When considering enamel caries, values obtained for sensitivity, specificity and accuracy were 48.15, 100 and 49.40% for visual examination, 48.15, 100.00 and 49.40% for tactile examination, 49.38, 50.00 and 49.40% for bitewing radiographs, 85.19, 50.00 and 84.34% for DIAGNOdent scores interpreted according to manufacturer«SQ»s cut-off limits and 81.48, 100.00 and 81.93% for DIAGNOdent scores interpreted according to newly formulated cut-off limits, respectively. At dentin caries cut-off levels, the values of sensitivity, specificity and accuracy for visual examination were 52.78, 89.36 and 73.49%; 50.00, 91.49 and 73.49% for tactile examination; 30.56, 82.98 and 60.24% for bitewing radiographs; 72.22, 76.60 and 74.70% for DIAGNOdent scores when interpreted according to manufacturer«SQ»s cut-off limits and 77.48, 74.47 and 75.90%, respectively, for the DIAGNOdent scores when interpreted according to the newly formulated cut-off limits. Conclusions: DIAGNOdent showed higher sensitivity and accuracy as compared with other conventional methods for detection of enamel caries, whereas for detection of dentinal caries, even though the sensitivity was high, accuracy of the DIAGNOdent device was similar to other conventional caries diagnostic methods.
|How to cite this article:|
Goel A, Chawla H S, Gauba K, Goyal A. Comparison of validity of DIAGNOdent with conventional methods for detection of occlusal caries in primary molars using the histological
gold standard: An in vivo study.J Indian Soc Pedod Prev Dent 2009;27:227-234
|How to cite this URL:|
Goel A, Chawla H S, Gauba K, Goyal A. Comparison of validity of DIAGNOdent with conventional methods for detection of occlusal caries in primary molars using the histological
gold standard: An in vivo study. J Indian Soc Pedod Prev Dent [serial online] 2009 [cited 2020 Oct 28 ];27:227-234
Available from: https://www.jisppd.com/text.asp?2009/27/4/227/57658
The process of caries activity varies widely with periods of progression alternating with periods of arrest or even reversal of partially damaged tissue.  As per this concept, a diagnostic method for dental caries should aim at detection of earlier pathological changes so as to ascertain the stage up to which the disease can be reversed. None of the traditional methods of caries diagnosis fulfill this requirement and are highly subjective. A visual examination alone has low sensitivity for detection of incipient carious lesions even though the specificity is high. Tactile examination of dental caries has been criticized because of the possibility of transferring microorganisms from one site to another leading to the fear of further spread of the disease in the same oral cavity.  Moreover, use of an explorer can cause irreversible traumatic defects in remineralizable incipient carious lesions.  Radiographs are generally recommended for detection of proximal carious lesions and are of limited use in the diagnosis of incipient occlusal caries. Moreover, these are associated with health hazards of radiation  and show underestimation of lesion size. 
To overcome these disadvantages of conventional caries diagnostic methods, many non-invasive methods of early caries detection and quantification have been developed and investigated, such as electrical conductance measurement, light scattering (fiber optic transillumination), quantitative laser-induced fluorescence device and DIAGNOdent (KaVo, Biberach, Germany), which is a chair side, battery-powered, quantitative, diode laser fluorescence device. DIAGNOdent utilizes a 655-nm-1mW laser diode excitation light source that is modulated to differentiate it from ambient light. Carious tooth structure fluoresces above 680 nm when encountering this light and this fluorescence is detected and quantified by the DIAGNOdent unit. ,
DIAGNOdent has demonstrated promising results for the detection of occlusal caries in studies undertaken in vivo and in vitro in permanent teeth but literature regarding its use in deciduous teeth is scanty. It could be argued that the results from permanent teeth could not be extrapolated to primary teeth because these have different morphological, anatomical and physiological characteristics. Early caries detection in primary teeth is of great importance because of the rapid rate of caries progression that results from the reduced enamel thickness of primary teeth. Therefore, the present investigation was conducted with the aim of evaluating and comparing conventional methods like visual criteria, use of explorer and radiographs with the DIAGNOdent device for detection of early occlusal caries in primary molars to validate the above methods by comparing with histopathological examination under a microscope (histological gold standard). Furthermore, this study also aimed to determine cut-off limits for DIAGNOdent readings for detecting enamel and dentinal caries in occlusal surface of primary teeth relative to the histological extent of the lesion.
Materials and Methods
A total of 84 primary first and second molars (both maxillary and mandibular) were selected in children who were in the late mixed dentition period (aged between 8 - 12 years). These teeth were indicated for extraction either for space management, balanced extraction or were due for exfoliation. Clinically, these teeth had either a sound occlusal surface or early caries. Teeth with occlusal restorations, occlusal fissure sealants, hypoplastic pits and frank occlusal cavitations resulting from caries attack were not taken up. After taking written consent of the parents, the selected teeth were subjected to radiographic evaluation for carious lesions using bitewing radiographs followed by visual examination, tactile and DIAGNOdent evaluation. The presence or absence of dental caries in bitewing radiographs was recorded using the criteria described by Ekstrand et al. 
After taking bitewing radiographs, patients performed supervised tooth brushing using a non-fluoridated toothpaste. If calculus was present, it was removed using an ultrasonic scaler tip. After this, the selected tooth in the mouth was dried for at least 5 s with compressed air and examined under a standard operating light. Presence or absence of carious lesions was recorded using Ekstrand's criteria. 
Subsequent to visual examination, all the fissures present on the occlusal surface of each selected tooth was explored using a Hu Friedy ESX-9 probe having a tip diameter of 22 microns, applying light pressure. The recordings were made according to Moller's criteria (1966).
DIAGNOdent [Figure 1] is a chair side, battery-powered, quantitative, diode laser-based fluorescent device. Two types of fiber optic tips are available with DIAGNOdent, a tapered one (tip A) designed for fissure caries and a flat one (tip B) for smooth surface caries. Tapered fiber optic tip (A) for fissure caries was used for caries detection on the occlusal surfaces of primary molars. After calibration with a ceramic standard, the standard (baseline) value for each individual was calibrated by measuring on the sound buccal surface of the tooth. This value was electronically subtracted from subsequent readings. Thereafter, the entire occlusal surface of the selected tooth was carefully scanned with a DIAGNOdent tip placed perpendicular to the tooth surface and tilted around to ensure that the tip picked up fluorescence from the slopes of the fissure walls. The maximum value from each measurement was registered and the mean value of the three readings was recorded. The sites with the highest values were marked on the drawing of occlusal surfaces of the teeth for subsequent sectioning and histological examination.
Subsequently, the teeth were extracted in the same appointment and were immersed in a 5% solution of sodium hypochlorite for 20 min followed by rinsing these samples in normal saline for 20 min in order to decontaminate and remove organic debris from their surfaces. The teeth were then stored in 10% formalin. The histological examination of the sections of the teeth under the microscope served as the gold standard. Roots were separated from the crowns by a diamond cutting disc under water coolant. Three or more 200-΅m-thick sections were prepared through each tooth so as to include the selected site using a hard tissue microtome (Leica, SP 1600,Nussloch, Germany). Subsequently, the sections were stained with Rhodamine B dye (0.1 mM), basic Fuchsin (0.5%) and counterstained with Acetic light green dye and were examined under the light microscope (Olympus, Olympus Corporation, America) under 4x magnification [Figure 2] to assess the absence/presence and, if present, the depth of the carious lesions. The histological findings were recorded using Ekstrand's criteria. 
Recordings of the conventional methods of caries diagnosis and DIAGNOdent were correlated with the histological gold standard to calculate sensitivity, specificity and accuracy of the caries diagnostic techniques at the occlusal enamel caries and dentin caries level. Furthermore, the values obtained for different caries diagnostic techniques were compared with one another.
Out of 84 teeth, one tooth was excluded from the sample for analysis of occlusal caries because its occlusal surface got damaged during sectioning and thus was not amenable to histological analysis. The histological evaluation revealed that of the 83 teeth, two showed no caries (score 0), two had caries limited to the outer half of the enamel (score 1), 43 teeth had caries extending to the inner half of the enamel (score 2), 19 teeth presented lesions in the initial half of the dentin (score 3) and 17 teeth had lesions involving advanced dentin lesions. The cut-off points for interpretation of readings of DIAGNOdent for caries detection in primary molars were determined after graphically plotting values of sensitivities and specificities for different possible cut-off limits at enamel, initial dentin and advanced dentin caries levels [Figure 3],[Figure 4],[Figure 5]. Cut-off limits with highest total sensitivity and specificity were selected for interpreting DIAGNOdent readings and were as follows: score 0-6, sound tooth surface; 7-20, enamel carious lesion; 21-34, initial dentinal lesions; ≥35, advanced dentinal lesions.
The scores of visual, tactile, bitewing radiographs and DIAGNOdent when cross-tabulated with histological scores are given in [Table 1],[Table 2],[Table 3],[Table 4],[Table 5]. [Table 6] and [Table 7] present the mean values of sensitivity, specificity and accuracy obtained for visual inspection, tactile examination, radiography and DIAGNOdent for enamel and dentinal caries cut-off levels, respectively. It was observed that at enamel caries cut-off levels, the value of sensitivity was lowest (48.15%) for visual and tactile methods and highest (85.19%) for DIAGNOdent scores, interpreted according to the manufacturer's cut-off limits. The value of specificity was 100% for visual, tactile and DIAGNOdent scores interpreted according to the newly formulated cut-off limits and lowest (50%) for bitewing radiographs and DIAGNOdent scores interpreted according to the manufacturer's cut-off limits. Similarly, accuracy was highest (84.34%) for DIAGNOdent scores interpreted according to the manufacturer's cut-off limits and lowest (49.40%) for visual, tactile and bitewing radiographic examination.
At dentin caries cut-off levels, the value of sensitivity was highest, 77.48% of that of the DIAGNOdent scores interpreted according to the newly formulated cut-off limit and lowest, 30.56% for bitewing radiographs. Further, the value of specificity was highest (91.49%) for tactile examination followed by visual (89.36%) and bitewing radiographs (82.98%) and lowest (70.21%) for DIAGNOdent scores interpreted according to the manufacturer's cut-off limits, whereas accuracy for caries diagnosis was highest (75.90%) for DIAGNOdent scores interpreted according to the newly formulated cut-off limits and lowest (60.24%) for bitewing radiographs.
Caries detection for the vast majority of the clinicians still relies upon radiographs, explorer and visual examination. With these 'crude' tools, clinicians are hampered in their ability to diagnose and monitor the carious lesion or assess the status of a stained pit or fissure. The development of a non-invasive technique or instrument, which can detect early demineralization on or beneath the enamel surface, is one of the desirable aims of the dental researchers. The DIAGNOdent uses laser excitation at 655 nm to distinguish between carious and healthy tooth structure. The device is based on the fluorescence caused by porphyrins present in carious tissue and not the amount of enamel demineralization.  Porphyrin fluorescence may lead to false positives because porphyrins are also found in stained, healthy fissures. , Furthermore, it was concluded that the DIAGNOdent was suitable for detecting small superficial lesions rather than deep dentinal lesions.  Thus, in vivo studies are required for validating the device for deciduous teeth because most of the previous studies for validating the device have been carried out on permanent teeth under in vitro settings.
The selected teeth had either sound occlusal surface or involved early carious lesions. Teeth with occlusal restorations, occlusal fissure sealants, hypoplastic pits and frank occlusal cavitations resulting from caries attack were excluded. This was done because it has been shown by earlier studies that presence of restorative material, fissure sealants or hypoplastic tooth surface leads to false-positive results by DIAGNOdent. ,
Even though professional tooth cleaning has been recommended by various authors and has also been followed in some of the in vitro investigations using pumice slurry and rubber cup, , but, such a procedure being cumbersome is not feasible in a clinical set up. Therefore, in this investigation, only supervised tooth brushing was performed. Tooth brushing protocol using water and toothbrush has also been used by Lussi and Francescut  in extracted primary molar teeth.
For visual examination of the occlusal surfaces at the enamel caries cut-off level, the value of sensitivity and specificity obtained in this study was in accordance with other in vitro investigations by Attrill and Ashley  and Lussi and Francescut  conducted on primary teeth. At dentin cut-off limits for visual examination, the values of sensitivity and specificity were similar to that of an in vivo study by Rocha et al.  conducted on primary molar teeth.
For tactile examination of occlusal surfaces at the enamel caries level, the values of sensitivity and specificity were similar to those reported by Lussi and Francescut  in an in vitro study on primary molar teeth whereas at dentin cut-off levels, the value of sensitivity was higher and specificity was somewhat lower than that of the results of the same in vitro study.
Difficulties in visually identifying the dentinal carious lesion below the sound enamel has led to the role of the bitewing radiograph in diagnosing occlusal caries to be reappraised. Recent in vitro studies have shown that clinicians diagnosed occlusal caries in the middle third of the dentin more reliably from a bitewing radiograph than from a visual, clinical examination alone (Ricketts et al.  ; Ketley and Holt  ). In the present investigation, for bitewing radiographs (Ekstrand's criteria  ) at enamel caries cut-off levels, the values of sensitivity and specificity were lower as compared with results of an in vitro study conducted on primary molar teeth by Attrill and Ashley  and Rocha et al..  At dentin cut-off limits, the values of sensitivity and specificity in the present investigation, the value of sensitivity was similar whereas specificity was lower as compared with the findings of an in vitro study conducted by Attrill and Ashley. 
In case of the use of DIAGNOdent in primary teeth, the cut-off limits for caries in occlusal surfaces is available from in vitro study by Lussi and Francescut.  However, the findings of the in vitro study or that of the permanent teeth cannot be extrapolated for clinical situations as DIAGNOdent readings vary with the storage medium used in the in vitro study as compared with the variables of temperature of oral cavity, saliva etc. in case of clinical studies. Therefore, new cut-off points for DIAGNOdent were tried to be formulated and used for the present study. The values of sensitivity and specificity were plotted against different cut-off limits for enamel, initial dentinal and advanced dentinal caries lesions. Those cut-off points were selected that provided optimal performance, i.e. highest sum of specificity and sensitivity at each caries level. It was seen that at higher cut-off limits, the value of sensitivity decreased but that of specificity increased. In case of doubt, higher cut-off limits, i.e. values with highest specificity were taken up. A similar method for derivation of optimal cut-off limits for DIAGNOdent has been used by other authors for permanent and deciduous teeth. ,,
At enamel cut-off limits, when DIAGNOdent scores were interpreted according to manufacturer's cut-off limits, the values of sensitivity and specificity were 85.19 and 50.00% whereas when DIAGNOdent scores were interpreted according to the newly formulated cut-off limits, the corresponding values were 81.48 and 100%, respectively. At dentin cut-off limits, when DIAGNOdent scores were interpreted according to the manufacturer's cut-off limits, the values of sensitivity and specificity were 72.22 and 76.60% whereas when DIAGNOdent scores were interpreted according to the newly formulated cut-off limits, the corresponding values were 77.48 and 74.47%, respectively.
The results of the present study revealed that:
Both visual and tactile methods had a tendency to underscore enamel carious lesions as sound (i.e., false-negative results) in 80% of the cases.DIAGNOdent scores interpreted according to both manufacturer's and newly formulated cut-off limits showed less false-negative findings for enamel caries.Dentin carious lesion could be detected correctly in 52.8% of the cases by visual examination, 50% of the cases by tactile examination and 80.6% of the cases by DIAGNOdent scores interpreted according to both manufacturer's and newly formulated cut-off limits.Sensitivity was lowest (48-53%) for visual and tactile methods for detection of occlusal caries lesions at both enamel and dentin cut-off limits.Tactile and bitewing radiographic examination provided no added benefit over visual examination for detection of occlusal carious lesions at both enamel and dentin cut-off limits.The newly formulated cut-off limits for DIAGNOdent provided a better combination of sensitivity and specificity as compared with cut-off limits given by the manufacturer.
It was observed that the newly formulated cut-off limits for DIAGNOdent scores provided a better combination of sensitivity and specificity as compared with other diagnostic methods at both enamel and dentin caries cut-off levels for occlusal surfaces. Therefore, from this study, it can be concluded that DIAGNOdent scores when interpreted according to newly formulated cut-off limits can serve as a valuable tool for screening of occlusal surfaces of the primary posterior teeth for incipient carious lesions.
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