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Year : 2009  |  Volume : 20  |  Issue : 3  |  Page : 326-331
A comparative evaluation of DIAGNOdent with visual and radiography for detection of occlusal caries: An in vitro study

1 Department of Pedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal, India
2 Department of Oral Pathology and Microbiology, Manipal College of Dental Sciences, Manipal, India

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Date of Submission01-Jul-2008
Date of Decision15-Apr-2009
Date of Acceptance30-Apr-2009
Date of Web Publication30-Oct-2009


Background: The diagnosis of dental caries is fundamental to the practice of dentistry. Despite the fact that dental caries has declined considerably, it is still a problem of great importance. The reduction in caries prevalence has not occurred uniformly for all the surfaces. The greatest reduction was observed at lesions located on smooth surfaces, so that occlusal caries are most common in children.
Aim: The purpose of this study is to determine the clinical efficacy of DIAGNOdent in detecting occlusal caries.
Materials and Methods: A total number of 50 teeth were subjected for visual, radiographic, and DIAGNOdent examinations. All the three methods were compared to histology which is a gold standard.
Results: The result obtained showed that DIAGNOdent is superior to visual and radiographic methods in diagnosing occlusal caries.

Keywords: Caries diagnosis, laser fluorescence, occlusal caries, DIAGNOdent

How to cite this article:
Sridhar N, Tandon S, Rao N. A comparative evaluation of DIAGNOdent with visual and radiography for detection of occlusal caries: An in vitro study. Indian J Dent Res 2009;20:326-31

How to cite this URL:
Sridhar N, Tandon S, Rao N. A comparative evaluation of DIAGNOdent with visual and radiography for detection of occlusal caries: An in vitro study. Indian J Dent Res [serial online] 2009 [cited 2019 Sep 16];20:326-31. Available from:
Diagnosis is becoming more important as methods of treatment also evolve and expand to include a wider range of options. There is now a requirement for a higher quality of diagnosis than was needed before.

When should fissure sealants be applied for preventive or therapeutic reasons? One school of thought maintains that it is more cost-effective to target sealants and place them only on teeth which are likely to become carious, rather than adopting a simpler but more expensive blanket policy which includes low risk teeth and individuals. The important point to stress, however, is that the success or failure of these selective approaches relies heavily on the quality of the original diagnosis of the presence and extent of caries.

Accurate sensitive diagnosis is imperative if the patients are to be categorized into risk groups on the basis of their past disease status and present disease activity. It is also becoming financially important that practitioners are able to identify high risk individuals, since the amount and complexity of the preventive care invested in these patients will largely depend upon the results of the practitioners' diagnostic assessments.

In recent years, however, clinicians have reported difficulties in diagnosing occlusal caries by visual examination alone. It was shown that visual examination performed worst in comparison to radiography, fiberoptic transillumination, and electric resistance.

Current clinical diagnostic techniques exhibit many disadvantages, e.g. in case of the explorer, transfer of cariogenic microorganisms from one site to another, and damage to the integrity of the enamel surface promoting conditions for caries development. [1]

Bitewing radiographs are a help in the detection of the noncavitated occlusal dental caries and combined with clinical inspection, achieve in permanent teeth a higher accuracy than visual inspection, visual inspection with magnification and visual inspection with light pressure probing. [2] But they do not enhance detection of initial occlusal caries lesions in enamel of either permanent or deciduous teeth and they increase the risk of x-ray overexposure.

Laser fluorescence seems to be promising for the detection and rectification of carious lesions on occlusal surfaces [3] and free smooth surfaces. [4] The laser fluorescence device DIAGNOdent has demonstrated promising results for the detection of occlusal caries in studies undertaken in vivo and in vitro in permanent teeth. [5],[6] One study dealt with diagnostic performance for deciduous teeth comparing two conventional methods with DIAGNOdent. [7]

The present study was performed to evaluate the specificity and sensitivity of laser0 fluorescence using DIAGNOdent in detection of occlusal caries in comparison to visual and radiographic methods.

   Materials and Methods Top

This study was conducted in Department of Pedodontics and Preventive Dentistry in collaboration with Department of Oral Pathology, Manipal College of Dental Sciences, Manipal.

A total of 50 teeth were selected from a pool of extracted teeth. Teeth contained 33 premolars and 17 permanent molars. All the teeth were having visually intact occlusal surface with variety of carious lesions but no obvious cavities.

The inclusion criteria for the teeth were the apparent absence of occlusal restorations, occlusal fissure sealants, hypoplastic pits, and frank occlusal cavitation.

Visual examination was performed using dental light reflector and syringe. After selection of teeth, in order to decontaminate and remove organic material and stains from the tooth they were immersed in 5.2% sodium hypochlorite solution for 20 min followed by rinsing in distilled water for 20 min. Teeth were cleaned using ultrasonic scaler and prophylactic paste. Teeth were thoroughly rinsed with distilled water to ensure complete removal of any remnants of prophylactic paste. Then teeth were mounted on plaster blocks for ease of handling. Occlusal surfaces were air dried using air water syringe and examined under standard dental operatory light. Scoring was given as follows based on Ekstrand criteria (1998) [8] [Table 1].

Radiographic examination was carried out on a standard intraoral periapical film (32 ΄ 41), (Kodak, Ectaspeed film).Teeth were radiographed using standard intraoral bitewing film (32 Χ 41, Kodak Ectaspeed film). Teeth were placed in such a way that occlusal plane was parallel to X-ray beam and perpendicular to the film. Exposure was taken with the standardization of 70 kvp, 8 Ma, 0.7 s with focal point to film distance of 20 cm.

Then the radiographs were viewed under standardized conditions using light box without magnification. The presence or absence of pit and fissure caries was recorded using criteria described by Ekstrand et al. (1998) [Table 2]. [8]

Laser fluorescence examination was performed using DIAGNOdent (Kavo, Biberach, Germany). It is a recently introduced laser-based instrument developed for detection and quantification of dental caries on smooth surfaces and occlusal surfaces. It operates with diode laser having a wavelength of l = 655 nm and 1 mW peak power. The light is transmitted through a descendent optic fiber to a handheld probe with a beveled tip with a fiber optic eye.

Both organic and inorganic molecules in the tooth substance absorb light, and fluorescence within the infrared spectra occurs. The emitted fluorescence as well as back scattered ambient light is collected through the tip, and passed in ascending fibers to a photodiode detector. To discriminate the fluorescence from the ambient light, the laser diode is modulated. By amplifying only the modulated portion of the signal, the ambient light is suppressed. The signal is finally processed and presented on the display between 0 and 99. [3]

DIAGNOdent consists of two probes, probe A for occlusal caries detection and probe B for smooth surface caries detection. In this study, probe A was used to examine the teeth [Figure 1].

Once the teeth were prophylactically cleaned and rinsed thoroughly, occlusal surfaces of test sites were examined using DIAGNOdent according to manufacturer's instructions. Probe A was used under cotton roll isolation and after air drying with an air syringe.

The instrument was calibrated using ceramic mounting that was provided by manufacturer. Probe A was place perpendicular to the test site and rotated along the fissure to completely scan the area. Base line reading for each tooth was taken by placing the probe on sound tooth surface. Three measurements were taken and mean of them was considered as a final base line value. Moment reading that indicates amount of demineralization at specific area was checked at mesial pit, central pit, and distal pit. Peak value that gives maximum amount of demineralization was checked by scanning the entire occlusal surface. Three measurements were performed for each tooth and mean of them was taken. This value was then subtracted from base line value to attain the final value. Then scoring was given according to the cutoff limits given by the manufacturer [Table 3].

Histologic examination was performed after the teeth were examined by all the three methods. Teeth were mounted on methyl metha acrylate and were hemisectioned using 0.1 mm thick diamond saw mounted on microtome (Leica, Germany) in a mesio distal direction with a thickness of approximately 100 ΅. The cut sections were mounted on glass slides with Canada balsam as a mounting medium. Sections were viewed under light microscope (Leica Dental Corp, Germany) with 40X magnification by a single examiner. Presence of caries in enamel or dentin was evaluated using Ekstrand criteria (1998) [6] [Figure 2],[Figure 3],[Figure 4],[Figure 5],[Figure 6],[Table 4].

   Results and Discussion Top

In the present study, out of 50 teeth 48 (96%) were diagnosed as cariously involved by visual examination while histology detected caries in 44 teeth (88%) [Figure 7]. The similar findings were observed by Rocha et al. [9] and Bengston et al. [10] where visual method detected caries in 100% of the sample whereas histology showed caries in 90% of the sample.

When comparisons were made between visual examination and histology, it was found that majority of the teeth (80.8%) seen with visual score of V2 (opacity or discoloration distinctly visible without air drying) were showing histology score as H2 (demineralization extended between 50% of enamel and one-third of dentin). Two teeth with V2 showed H0 and 10 teeth showed H1 [Figure 8]. The comparisons were statistically significant (P = 0.034). From this it may be concluded that even though in majority of the cases visual examination has detected the caries, in two teeth it gave the score as V0 while histology has shown caries in these teeth. Similarly in two teeth histology failed to detect the caries while visual method scored it as a carious lesion. These findings obtained in the present study are much consistent with that of Ekstrand et al. [11] who detected occlusal caries using visual method and histology indicating that visual examination and laser fluorescence have performed better than radiography and probing. The reason for over and under scoring can be attributed to the field conditions as stated by Shi et al., [6] who reported that adequate isolation and air drying of tooth is required before examination. In the present study teeth were isolated with cotton rolls, air dried with three-way syringe and then examined under standard dental operatory light.

In case of bitewing radiography it has detected caries in eight teeth (16%), where histology showed evidence of caries at various levels in 88 teeth (88%) [Figure 9]. This large variation in these two methods was also reported in other studies of Rocha et al., [9] Souza-Zaroni et al., [12] and Burin et al. [13] Only in seven teeth the radiographic findings coincided with histology. Radiographs are routinely used for diagnosing occlusal and proximal caries. However, it has no value for occlusal enamel caries detection and only a limited value is elicited for proximal enamel caries detection as stated by Traneus et al. [14] They are also only two-dimensional representation of the subject. So there are chances that many times it may miss out the carious lesions. Moreover to detect dental caries on radiographs, minimum of 40% mineral loss is required which is usually not present in cases of early enamel caries. The results obtained in present study also matches with that of some of the previous studies conducted by Shi et al. [6] where it was reported that radiography is inferior to visual and laser fluorescence methods in detection of caries.

When all the test teeth were examined in the present study with laser device DIAGNOdent, out of 50 teeth 44 (88%) were diagnosed as carious [Figure 10]. In in vitro studies done by Attrill and Ashley, [7] Antonnen et al., [15] Francescut and Lussi [16] found 100% clinical success of DIAGNOdent. But the conditions of the teeth selected were not explained clearly. Probably, the variation could also be due to the difference in sample size and selection criteria of teeth. In in vitro group in the present study out of 50, 22 teeth (84.6%) showed DIAGNOdent reading as D3 (dentin demineralization) and histology score as H2 (demineralization extended between 50% of enamel and one-third of dentin) [Figure 10]. However, in case of 13 teeth DIAGNOdent has over scored the caries where histology revealed no caries in four teeth and outer enamel caries in nine teeth. There are various causes for over scoring of teeth by DIAGNOdent. One prerequisite for DIAGNOdent is that the tooth surface to be examined should be carefully cleaned because the instrument is very sensitive to the presence of stains, deposits, and calculus, which may be registered as a change in enamel or dentin. Therefore, careful inspection of the tooth surface is recommended.

The fundamental basis for detection and quantification of carious lesion by DIAGNOdent method is registration of altered physical characteristics of carious hard tissues relative to surrounding sound surfaces. The principal limitation of the method is that an increased reading could reveal any change in the physical properties of the tooth structure, such as caries, disturbed tooth development, or mineralization as well as deposits of calculus or organic material. Therefore, clinical experience is a fundamental prerequisite for using the instrument as an aid to detection of clinical caries. As mentioned before in this study DIAGNOdent has over scored 13 teeth for which histology revealed no visible caries.

According to Ekstrand's [8] visual scoring system, the presence of discoloration, visible without air drying is an indicator of demineralization involving between 50% of the enamel and the outer third of dentin which is considered a 'sound site' at the dentine caries level. When discolored sites were evaluated by DIAGNOdent there was high tendency for these sites to be over scored, resulting in high rate of false positives. Nevertheless, great care was taken to clean the sites beforehand; it is unlikely that this is the reason. Recent evidence of studies conducted by Sheehy et al., [5] Francescut and Lussi, [16] Heinrich-weltzien et al. [17] also indicate that DIAGNOdent tends to over score discolored sites. At similar lesion depths, discolored fissures resulted in DIAGNOdent median values about 5-7 units higher than in opaque or nondiscolored fissures.

Apart from this when DIAGNOdent was compared to visual and radiographic methods it has shown much superior results in diagnosing the caries.

The comparisons obtained statistically in visual and DIAGNOdent were found to be significantly comparable. A total of 48 teeth, which were diagnosed as carious by visual method, also showed increased values of laser fluorescence. This reveals that there is a significant correlation between the visual and laser fluorescence in detection of occlusal caries. But in cases of stained occlusal surfaces if the treatment decision is solely based on DIAGNOdent reading there will be a tendency to overestimate the lesion stage and a higher risk of overtreatment. In such cases, visual examination is more appropriate to the clinician or at least the dentist using the laser fluorescence system must be aware of its limitations before reaching a treatment decision. Burin et al. [12] are also of the opinion that visual inspection alone is significantly better than DIAGNOdent with respect to specificity.

Similarly DIAGNOdent has shown high sensitivity (100%) and acceptable specificity (44%) in detection of occlusal caries when compared to visual and radiographic methods. It has shown a positive predictive value of 76.2%. This high sensitivity and acceptable specificity was obtained also in some other studies conducted by Rocha et al. [15] and Bengston et al.[10] In contrast, Yaziki et al. [18] reported that DIAGNOdent has shown higher specificity values than sensitivity.

   Conclusions Top

Caries prevention is critical in children, especially in developing countries where younger generations are acquiring more westernized dietary habits, which is expected to contribute to an increase in dental caries. Despite there is a reduction in prevalence of dental caries it is still a problem of great importance. The reduction of caries prevalence has not occurred uniformly for all the dental surfaces. Several studies have been undertaken with the objective of determining the most accurate and precise method for detection of carious lesions among conventional and new methods. In this study, the efficacy of laser device (DIAGNOdent) in detection of caries was evaluated with histological gold standard.

The following conclusions were made from this study:

  1. The laser fluorescence device DIAGNOdent has shown more superior results in diagnosing the caries which is almost comparable to histological gold standard.
  2. DIAGNOdent has shown very good sensitivity and specificity in diagnosing the caries.
  3. Visual and laser fluorescence (DIAGNOdent) both have shown similar performance in terms of sensitivity and specificity.
  4. Radiography performed poorly in diagnosing occlusal caries compared to other three methods. However, it has shown accurate results in reference to dentinal caries.
  5. The laser device DIAGNOdent can be used as a valuable and preventive diagnostic tool as an adjunct to visual examination.

Limitations and recommendations of the study

  1. Even though DIAGNOdent has excellent sensitivity and specificity, in some cases it has over scored the teeth.
  2. The cutoff limits that were given by the manufacturer are often confusing. So more precise values are required to exactly locate the carious lesion.
  3. The laser device DIAGNOdent is not able to detect the amount of demineralization.
  4. An adequate learning and experience is required for its precise use before considering it as a reliable diagnostic method.

   References Top

1.Yasin OM. in vitro studies of the effect of a dental explorer on the formation of an artificial carious lesion. ASDC J Dent Child 1995;62:111-7.  Back to cited text no. 1      
2.Lussi A, Imwinkelried S, Pitts N, Longbottom C, Reich E. Performance and reproducibility of a laser fluorescence system for detection of occlusal caries in vitro, Caries Res 1999;33:261-6.  Back to cited text no. 2      
3.Hibst R, Gall R. Development of diode laser based fluorescence caries detector. Caries Res 1998;32:294 (Abstract).  Back to cited text no. 3      
4.Pinelli C, Campos Serra M, de Castro Monteiro Loffredo L. Validity and reproducibility of a laser fluorescence system for detecting the activity of white spot lesions on free smooth surfaces in vivo. Caries Res 2002;36:19-24.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]  
5.Sheehy ECBrailsford SR, Kidd EA, Beighton D, Zoitopoulos L. Comparison between visual examination and a laser fluorescence system for in vivo diagnosis of occlusal caries. Caries Res. 2001;35:421-6.  Back to cited text no. 5      
6.Shi XQ, Welander U, Angmar-Mansson B. Occlusal caries detection with KaVo DIAGNOdent and radiography: An in vitro comparison. Caries Res. 2000;34:151-8.  Back to cited text no. 6      
7.Attrill DC, Ashley PF. Occlusal caries detection in primary teeth: A comparison of DIAGNOdent with conventional methods. Br Dent J 2001;190:440-3.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]  
8.Ekstrand KR, Ricketts DN, Kidd EA, Quist V. Detetion, diagnosing, monitoring and logical treatment of occlusal caries in relation to lesion activity and severity: An in vivo examination with histologic validation. Caries Res 1998;32:247-54.   Back to cited text no. 8      
9.Rocha RO, Ardengi TM, Oliveria LB, Rodrgues CR, Ciamponi AL. in vivo effectiveness of laser fluorescence compared to visual inspection and radiography for the detection of occlusal caries in primary teeth. Caries Res 2003;37:437-41.  Back to cited text no. 9      
10.Bengtson AL, Gomes AC, Mendes FM, Cichello LR, Bengtson NG, Pinheiro SL. Influence of examiners clinical experience in detecting occlusal caries lesions in primary teeth. Pediatr Dent 2005;27:238-43.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]  
11.Ekstrand KR, Kuzmipa I, Bjorndal L, Thylstrup A. Relationship between external and histologic features of progressive stages of caries in the occlusal fossa. Caries Res 1995;29:243-50.  Back to cited text no. 11      
12.Souza -Zaroni WC, Ciccone JC, Souza- Gabriel AE, Ramos RP, Corona SA, Palma-Dibb RG. Validity and reproducibility of different combinations of methods for occlusal caries detection: An in vitro comparison. Caries Res 2006;40:194-201.  Back to cited text no. 12      
13.Burin C, Loguercio AD, Grande RH, Reis A. Occlusal caries detection: A comparision of laser fluorescence and conventional methods. Pediatr Dent 2005;27:307-12.  Back to cited text no. 13  [PUBMED]  [FULLTEXT]  
14.Traneus S, Shi XQ, Angmar-Mεnsson B. Caries risk assessment: Methods available to clinicians for caries detection. Community Dent Oral Epidemiol. 2005;33:265-73.   Back to cited text no. 14      
15.Anttonen V, Seppa L, Hausen H. Clinical study of the use of the laser fluorescence device DIAGNOdent for detection of occlusal caries in children. Caries Res 2003;37:17-23.  Back to cited text no. 15      
16.Francescut P, Lussi A. Correlation between fissure discoloration, DIAGNOdent measurements, and caries depth: An in vitro study. Pediatr Dent 2003;25:559-64.  Back to cited text no. 16  [PUBMED]    
17.Heinrich-Weltzien R, Kuhnisch J, Oehme T, Ziehe A, Stosser L. Comparison of different DIAGNOdent cut off limits for in vivo detection of occlusal caries. Oper Dent 2003;28:672-80.  Back to cited text no. 17      
18.Yazici AR, Baseren M, Gokalp S. The in vitro performance of a laser fluorescence and caries detector dye for detecting residual carious dentin during tooth preparation. Quintessence Int 2005;36:417-22.  Back to cited text no. 18  [PUBMED]  [FULLTEXT]  

Correspondence Address:
N Sridhar
Department of Pedodontics and Preventive Dentistry, Manipal College of Dental Sciences, Manipal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.57376

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]

  [Table 1], [Table 2], [Table 3], [Table 4]

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