Relationship between the color of carious dentin with varying lesion activity, and bacterial detection

OBJECTIVES: To investigate the relationship between the color of carious dentin with varying lesion activity, and bacterial detection in the lesions. METHODS: In 26 extracted human molars with coronal dentin caries and four extracted sound human molars, dentin was removed by a round bur every 150 microm from the dentin surface, in the direction of the pulp chamber. Before and after removal, images of nine-color samples and the dentin surface stained with a caries detector dye (1% acid red in propylene glycol) were taken simultaneously by a charge-coupled device (CCD), and dentinal tissue samples were taken with a new round bur. From the images, corrected L*, a* and b* values (CIE 1976 L*a*b* color system) of the dentin surfaces were calculated from the color changes of the nine-color samples. Bacterial DNA in the dentinal tissues was detected by polymerase chain reaction. RESULTS: Before removal of dentin, the L* of sound molars (L*>50) was significantly larger than that of carious molars (L*<50) (ANOVA, Scheffe's F-test, P<0.05). In addition, the carious molars were divided into type I (a*>20, characteristics of active caries) and type II (a*<20, characteristics of arrested caries), and there was a significant difference in the a* value (P<0.05). For both carious types, the area under the receiver operating characteristic curve of L* was significantly larger than that of a* or b* (univariate Z score test, P<0.05), and the rate of bacterial detection decreased as the L* of dentinal tissue increased, and bacterial DNA was not detected when L* was >60. CONCLUSIONS: Sound and types I and II carious dentin were discriminated by the combination of L* and a* values of dentinal tissue stained with the caries detector dye before removal of dentin. In carious lesions, the a* values of carious dentin stained with the dye were related to the carious lesion activity before removal of carious tissue, and the L* values were related to the degree of caries progression.     

The relationship between the color of carious dentin stained with a caries detector dye and bacterial infection

This in vitro study aimed to design a method for the objective evaluation of carious dentin using numerical values. This study also investigated the relationship between the color of carious dentin stained with a caries detector dye using this objective method and the rate of bacterial detection as detected by a polymerase chain reaction (PCR). In 15 molars with occlusal dentin caries and three extracted sound molars, dentin was removed in multiple steps with 300 microm removed each step. Before and after every removal, images of a color-matching sticker and carious surfaces stained with a caries detector dye were acquired simultaneously using a CCD camera and dentinal tissue samples were removed with a round bur. Next, corrected L*, a* and b* values of the carious surfaces (CIE 1976 L*a*b* color system) were calculated from the color changes of the stickers in the images. In addition, bacterial DNA in the dentinal tissue was detected by PCR. From evaluations of the receiver operating characteristic curves for the L*, a* and b* values, the L* value was determined to be a more useful parameter than a* or b* for detecting bacterial infection using the caries detector dye. The bacterial detection rates of carious dentin decreased as the L* values of carious dentin stained with the dye increased. When the L* values were more than 60, the dentin had no bacterial infection. This study clarified the relationship between the colors of lesions stained with a caries detector dye and the rates of bacterial detection.     

Evaluating the objectivity of caries removal with a caries detector dye using color evaluation and PCR

OBJECTIVES: This laboratory study evaluated the objectivity of caries removal with a caries detector dye by color and bacterial evaluations. METHODS: In 41 cases of dentin caries (32 extracted human molars), carious tissues were removed using a caries detector dye. Images of dentin surfaces with color-matching stickers were acquired using a CCD camera, and dentinal tissue samples were collected with new round burs. Corrected L*, a* and b* values (CIE 1976 L*a*b* color system) of dentin surfaces were calculated from the sticker color changes. In addition, bacterial DNA in dentinal tissues was detected by the polymerase chain reaction. RESULTS: The intra-class correlation coefficient of the corrected L*, a* and b* values was 0.34, 0.30 and 0.49, respectively. There were significant inter-operator differences (P<0.05). Seventeen of 41 specimens contained bacterial DNA after caries removal. CONCLUSIONS: Results showed that objectivity of caries removal using the caries detector dye with visual inspection was low.     

In vitro study of caries detection through sound dentin using a laser fluorescence device,DIAGNOdent

The objective of this study was to investigate the feasibility of proximal surface caries detection using a laser fluorescence device, DIAGNOdent, through the sound dentin surrounding the cavity wall after removal of occlusal caries. Extracted sound human molars were ground to prepare horizontal and vertical dentin plates 1.4 mm thick. Extracted carious human molars were reduced in thickness horizontally from the occlusal surfaces until exposure of the dentin caries. The dentin plate was placed on the carious tooth. Before and after gradual thinning of the dentin plate from approximately 1.4 mm to 0.2 mm thick, the dentin caries was measured 10 times through the plate by the laser fluorescence device with a cone-shaped tip or a broad tip. When the dentin plate was reduced to less than 0.3 mm thick (using a combination of a horizontal plate and cone-shaped tip) or 0.2 mm thick (using the other combinations), the values measured with the laser fluorescence device were significantly larger than the values before reducing the thickness of the dentin. Based on these results, the device offers potential use as one of the screening tests for proximal surface caries detection through sound dentin when the sound dentin between tip and caries is thin.     

Relationship between bacterial infection and evaluation using a laser fluorescence device, DIAGNOdent

The aim of this in vitro study was to investigate the relationship between bacterial infections in carious dentin when detected by two different methods -- polymerase chain reaction (PCR), and a laser fluorescence device, DIAGNOdent. Dentin was removed every 300 micro m in the direction of the pulp chamber in 10 extracted molars with occlusal dentin caries and 3 extracted sound molars. Dentin surfaces were evaluated using DIAGNOdent, and dentinal tissue samples were removed by using a round bur before and after each removal. Bacterial DNA in the dentinal tissues was detected by PCR, using primers based on the nucleotide sequence of a conserved region of the 16S rDNA, and yielded a PCR product of 466 bp. The rates of bacterial detection increased as the DIAGNOdent values increased. In the 10 specimens, the lowest DIAGNOdent value at which bacteria were detected was 15.6; at DIAGNOdent values below 15.6, no bacteria were detected. The results of a receiver operating characteristic (ROC) curve for the DIAGNOdent values showed that the area under the ROC curve was 0.91. This study clarified the relationship between the DIAGNOdent values of dentin caries and the rates of bacterial detection.     

The effect of distance and tooth structure on laser fluorescence caries detection

The DIAGNOdent, a device used in caries detection, uses a laser to excite fluorescence from pigments in carious tooth structure. In clinical use assessing occlusal surfaces, distance and tooth structure may separate the instrument's tip from the fluorescent source.The aim of this in vitro study was to examine the effect of distance and tooth structure on laser fluorescence (LF) readings.In one set of experiments, a porphyrin pigmentin oil suspension was used as a LF signal source. Thin slices of enamel and dentin were obtained from extracted molars. Pigment-induced LF readings were obtained when these slices were placed between the porphyrin pigment and the LF instrument's tip. The effect of either demineralized or intact tooth tissue on pigment-induced LF readings was assessed.In other experiments on extracted molars with small occlusal caries, LF readings were taken from pit/fissure sites before and after removal of the occlusal surface.LF readings are proportional to pigment con-centration and inversely proportional to the distance between the suspension and the instrument's tip. Enamel, demineralized enamel,dentin, and demineralized dentin all caused significant reductions in LF signal, all readings being taken with the same tip-pigment distance. Demineralized enamel (white with intact surface) caused the most reduction.After sectioning of carious teeth, there was a significant increase in LF readings.The results of this study indicate that distance and the presence of tooth structure between the carious lesion and the instrument's tip reduce LF readings. These results indicate that anatomic factors interfere with the LF device's ability to assess occlusal caries. DIAGNOdent readings should not be relied on when making diagnostic decisions.     

Dentine microhardness after different methods for detection and removal of carious dentine tissue

There are several methods for identifying carious dentinal tissue aiming to avoid removal of healthy dentinal tissue.

Objectives

The purpose of this study was to test different methods for the detection of carious dentinal tissue regarding the amount of carious tissue removed and the remaining dentin microhardness after caries removal.

Material and methods

The dentin surfaces of 20 bovine teeth were exposed and half of the surface was protected with nail polish. Cariogenic challenge was performed by immersion in a demineralizing solution for 14 days. After transverse cross-section of the crown, the specimens were divided into four groups (n=10), according to the method used to identify and remove the carious tissue: "Papacárie", Caries-detector dye, DIAGNOdent and Tactile method. After caries removal, the cross-sectional surface was included in acrylic resin and polished. In a microhardness tester, the removed dentin thickness and the Vickers microhardness of the following regions were evaluated: remaining dentin after caries removal and superficial and deep healthy dentin.

Results

ANOVA and Tukey''s test (α=0.05) were performed, except for DIAGNOdent, which did not detect the presence of caries. Results for removed dentin thickness were: "Papacárie" (424.7±105.0; a), Caries-detector dye (370.5±78.3; ab), Tactile method (322.8±51.5; bc). Results for the remaining dentin microhardness were: "Papacárie" (42.2±10.5; bc), Caries-detector dye (44.6±11.8; abc), Tactile method (24.3±9.0; d).

Conclusions

DIAGNOdent did not detect the presence of carious tissue; Tactile method and "Papacárie" resulted in the least and the most dentinal thickness removal, respectively; Tactile method differed significantly from "Papacárie" and Caries-detector dye in terms of the remaining dentin microhardness, and Tactile method was the one which presented the lowest microhardness values.     

In vitro quantification of smooth surface caries with DIAGNOdent and the DIAGNOdent pen

OBJECTIVE: A new generation of the laser fluorescence device, DIAGNOdent, for caries detection and quantification has been introduced recently. It is the DIAGNOdent pen. The aim of this study was to compare the validity and reliability of both laser-based devices, DIAGNOdent and the DIAGNOdent pen, in quantifying smooth surface caries. MATERIAL AND METHODS: The material comprised a sample of 52 premolar teeth extracted on orthodontic indication. The teeth were visually sound or had various stages of non-cavitated carious lesions on smooth surfaces. All teeth were photographed and measured with both DIAGNOdent and the DIAGNOdent pen by two examiners independently. The teeth were then sectioned into 300-microm slices and analysed under a microscope for verification of lesion depth. Histopathological analyses were performed by two observers to assess lesion depth, which was classified into five categories ranging from sound to dentinal caries. Reliability and validity of the two devices were evaluated in terms of intra-class coefficients and Spearman rank correlation coefficient, respectively. The relation between measurements performed by DIAGNOdent and the DIAGNOdent pen was analyzed using Pearson's correlation coefficient. RESULTS: Both DIAGNOdent and the DIAGNOdent pen had excellent intra-observer agreement and acceptable inter-observer agreement. The correlation with histology for DIAGNOdent and the DIAGNOdent pen ranged between 0.47 and 0.57, although the correlation between DIAGNOdent and the DIAGNOdent pen was high. CONCLUSIONS: In this in vitro study, the new laser fluorescence device, the DIAGNOdent pen, showed similar reliability and validity at quantification of smooth surface caries compared to the conventional DIAGNOdent device. Agreement between DIAGNOdent and the DIAGNOdent pen was excellent.     

Caries detection and quantification with DIAGNOdent: prospects for occlusal and root caries?

A possible consequence of light absorption as the interaction of electromagnetic radiation with molecules of the tooth's hard substances is, apart from the emission of heat, fluorescence. It was demonstrated that the emission spectra of enamel, dentin, and caries look alike upon excitation with red light; however, fluorescence increases with the process of carious destruction. Based on that, the DIAGNOdent System was developed, which simultaneously injects red light into the tooth surface and detects the resulting fluorescence. Due to this design, clinical application is currently limited to accessible occlusal and smooth surfaces. For occlusal caries detection, it was shown that validity and reproducibility could be optimized over classical diagnostic tests for deep dentin lesions with seemingly intact surfaces. The detection of root caries does not play a relevant role in the directly accessible areas, but estimation of the lesion's activity and progression rate is a prerequisite for differentiated lesion management Excellent reproducibility of the laser fluorescence measurements was confirmed for this scenario. Lesions with a soft surface texture show significantly higher fluorescence values than leathery or hard lesions, and values also increase with increasing cavity depth. DIAGNOdent offers the potential to improve follow-ups and estimation of the prognosis and to support clinical management of primary carious lesions.     

Evaluation of laser fluorescence for differentiating caries dye-stainable versus caries dye-unstainable dentin in carious lesions

PURPOSE: To assess the performance of laser fluorescence (DIAGNOdent, "DD") for differentiating carious versus non-carious dentin during caries excavation using caries dye as the gold standard. METHODS: The superficial carious dentin surfaces of lesions in 25 teeth were exposed, and the surface evaluated by DD. Next, caries dye was applied and the surface was observed for dye staining. The lesion was then excavated approximately 0.5 mm with a round bur. The resulting surface was evaluated by DD, and the above sequence was repeated until three non-stained surfaces were evaluated by DD. Using "caries dye staining" as the gold standard, correct classification proportion was calculated at each DD cutpoint in the dataset. Using the optimal cutpoint, sensitivity, specificity and likelihood ratios were calculated. Non-parametric ROC analysis was performed and AUC calculated. RESULTS: With an optimal cutpoint of 11 or 12, DD was highly accurate in discriminating between dye-stainable and dye-unstainable surfaces, producing a correct classification proportion of over 98% and an AUC of 0.999 for all 176 surfaces. These results support further refinement of DD for use in caries excavation and further research relating DD to other caries excavation endpoints.     

Correlation between Laser Fluorescence Readings and Volume of Tooth Preparation in Incipient Occlusal Caries In Vitro

Objective:  This study evaluated the correlation between laser fluorescence readings and the extent of incipient occlusal caries as measured by the volume of tooth preparation in vitro.
Materials and Methods:  One hundred and three permanent molars and premolars containing incipient occlusal pit-and-fissure caries and sound occlusal surfaces (1/4 of the sample, control) were selected. DIAGNOdent (KaVo Dental Corporation, Lake Zurich, IL, USA) readings were obtained according to manufacturer instructions. Caries was removed with 1/4 round burs in high speed. The volume of tooth preparation was measured using a surrogate measure based on the amount of composite needed to fill the preparations. Sensitivity and specificity using different cutoff values were calculated for lesions/preparations extending into dentin. The results were analyzed statistically.
Results:  The Pearson correlation for preparation volume and DIAGNOdent reading measurements was low ( r  = 0.285). Sensitivity and specificity of DIAGNOdent for detection of dentinal lesions were 0.83 and 0.60, and 0.66 and 0.73 for the cutoff values of 20 and 30, respectively.
Conclusions:  Within the limitations of this study, laser fluorescence measured with DIAGNOdent does not correlate well with extent of carious tooth structure in incipient occlusal caries.

CLINICAL SIGNIFICANCE

Clinicians should not rely only on DIAGNOdent readings to determine the extension of incipient occlusal caries.
( J Esthet Restor Dent 22:31–41, 2010)     

A comparison of root caries diagnosis based on visual-tactile criteria and DIAGNOdent in vivo

Objectives

This clinical study aimed to evaluate the validity of using DIAGNOdent in diagnosing root caries, and to assess the sensitivity and specificity of different cut-off DIAGNOdent values in assessing root caries with reference to visual-tactile criteria.

Methods

Exposed root surfaces were assessed by one examiner for root caries on 266 subjects using visual-tactile criteria and DIAGNOdent 2095 after dental scaling. Associations between DIAGNOdent values and visual-tactile diagnosis of root caries were determined. The cut-off level for statistical significance was 0.05. The sensitivity and specificity of DIAGNOdent with difference cut-off points were analysed compared to visual-tactile diagnosis of root caries.

Results

There was significant difference between DIAGNOdent values obtained from sound and carious root surfaces (p < 0.001). On carious surfaces, active root caries obtained significantly higher DIAGNOdent values than inactive root caries (p < 0.001). With increasing cut-off point DIAGNOdent values from 5 to 35, sensitivity decreased from 91.4% to 16.2% and specificity increased from 64.4% to 98.2%. A cut-off point of DIAGNOdent value between 5 and 10 produced the highest combined sensitivity and specificity.

Conclusions

There was a significant difference in DIAGNOdent values between sound and carious root surfaces diagnosed by visual-tactile criteria supporting the validity of DIAGNOdent for assessing root caries. A DIAGNOdent value between 5 and 10 produced the highest combined sensitivity and specificity when visual-tactile assessment of root caries was regarded as the criterion. These findings have implications in using and explaining DIAGNOdent values in assessing root caries.     

The nature of the remaining dentin surface following application of Carisolv solution

PURPOSE: To evaluate the effect of Carisolv solution on the topography and surface hardness of dentin. METHODS: Two separate studies were carried out. Atomic force microscopy (AFM) was employed to visualize dentin surface topography on slices of previously extracted non-carious and carious teeth following the passive application of Carisolv gel for 30- and 60-second periods. A Wallace hardness instrument was used to measure the dentin surface hardness following active caries removal with Carisolv gel and the specially designed instruments. Conventional caries removal with dental burs and non-carious dentin acted as controls for the latter study. RESULTS: AFM revealed that the passive application of Carisolv gel resulted in smoother surfaces than observed on carious and non-carious dentin. There was a statistically significant difference between the mean hardness values for non-carious and Carisolv-treated dentin (P< 0.05). There was no statistically significant difference between the non-carious and bur-treated dentin nor the Carisolv and bur-treated dentin.     

Partial caries removal in primary teeth: association of clinical parameters with microbiological status

The relationship between clinical characteristics of carious dentin and bacterial colonization after partial caries removal is not completely understood. The aim of this study was to compare microbial counts between categories of carious dentin color, consistency and humidity, and to evaluate the correlation between these characteristics and the presence of cariogenic microorganisms in deep cavities (2/3 or more of the dentin thickness) submitted to partial caries removal. Sixteen primary teeth were submitted to the removal of all carious tissue from the lateral walls of the cavity, whereas carious tissue of the pulp wall was removed superficially. Dentin in the pulp wall was classified according to color, consistency and humidity immediately after cavity preparation and 3-6 months after cavity sealing and a tissue sample was collected on the same occasion for microbiological evaluation. Before sealing, Streptococcus mutans (p = 0.033) and Lactobacillus spp. (p = 0.048) counts were higher in cavities with humid dentin compared to cavities with dry dentin. A negative correlation was observed between carious dentin consistency and S. mutans count during this phase (r(s) = -0.571; p = 0.020). Arrest of dentinal caries lesions was observed after sealing, which was characterized by a reduction of bacterial counts and changes in dentin color, consistency and humidity, irrespectively of baseline dentin characteristics. The clinical characteristics of carious dentin change after the period of cavity sealing and cannot be applied as absolute indicators to limit the excavation of carious dentin when minimally invasive techniques are used.     

Evaluation of a new caries detecting dye for primary and permanent carious dentin

OBJECTIVE: This study evaluated the clinical efficacy of a new caries detecting dye using a laser fluorescence device (DIAGNOdent). METHOD: Primary and permanent teeth with dentin caries were stained with Caries Check (CC), containing 1% acid red in polypropylene glycol (MW=300) or Caries Detector (CD), containing 1% acid red in propylene glycol (MW=76). Primary-CC, primary-CD, permanent-CC and permanent-CD groups were prepared. In the CC groups, stained dentin was completely removed. In the CD groups, pink-stained dentin was retained according to the manufacturers' instructions. Cavities before and after caries removal were measured with the DIAGNOdent. Data were analyzed using ANOVA and Fisher's PLSD multiple comparison test at alpha=0.05. Regression analyses were performed between DIAGNOdent readings and scores obtained from the clinical parameters. RESULTS: For all groups, there were no significant differences in the DIAGNOdent readings before treatment. The DIAGNOdent readings after caries removal were: primary-CC (16.0+/-17.6), primary-CD (9.6+/-5.2), permanent-CC (11.0+/-7.0) and permanent-CD (7.1+/-3.8). Significant differences were identified between the permanent-CC and primary-CD, and permanent-CC and permanent-CD subgroups but not for the primary subgroups. Correlation coefficients between DIAGNOdent readings and clinical parameters were low. CONCLUSIONS: When dentin stained with Caries Check was completely removed, the DIAGNOdent readings were higher than those recorded when palely-stained pink dentin was retained with the Caries Detector, with significant difference observed for the permanent teeth. Caries Check may be used clinically to avoid excessive removal of caries-affected or sound dentin in permanent teeth but not in primary teeth.     

Application of DIAGNOdent as a guide for removing carious dentin with Er:YAG laser

OBJECTIVES: The purpose of this study was to investigate the DIAGNOdent values applicable as a guide for removal of outer layer of carious dentin with Er:YAG laser. METHODS: Carious dentin of human extracted molars was removed by bur with Caries Detector (Group 1: red stained dentin was left, Group 2: light pink stained dentin was left) and by Er:YAG laser with DIAGNOdent value as a guide (30>Group 3>21, 20>Group 4>11, 10>Group 5). The cavity floor dentin after removing carious dentin was examined using microradiograms, EPMA and SEM. RESULTS: The cavity floor dentin of group 1,3 showed the decreases in the degree of X-ray absorption. In group 2,4 and 5, decrease of Ca, P were not observed. The decrease of Mg was observed on the more superficial part of the cavity floor for group 3 than for group 4. CONCLUSIONS: When carious dentin was removed using Er:YAG laser, the carious dentin outer layer was ideally removed with DIAGNOdent values: 11-20. DIAGNOdent values: 11-20, could indicate the completion of outer layer removal of carious dentin with Er:YAG laser, but there are some problems that must be addressed before the clinical application.     

Dentinal composition and Knoop hardness measurements of cavity floor following carious dentin removal with Carisolv

This study evaluated the dentinal composition and Knoop hardness measurements of the cavity floor following the removal of carious dentin by the Carisolv chemo-mechanical caries removal system, in vitro. The carious dentin of 25 extracted human teeth was removed by using Carisolv for one minute with instruments and excavation that was performed until the gel was clear. Caries removal with a sharp explorer was verified according to the color and hardness of the lesion, then, by means of DIAGNOdent. Atomic analysis of treated cavities was performed by energy dispersive x-ray spectroscopy (SEM-EDX) and the Knoop hardness number (KHN) of the cavity floor was determined. Surface characteristics were observed by the scanning electron microscope (SEM). Adjacent sound dentin was used as a control reference. No significant differences were found between the quantities of calcium content (Ca weight %), phosphorus content (P weight %) and the Ca/P weight ratio of Carisolv cavities with that of the adjacent, sound dentin (p<0.01). KHN of the Carisolv cavity floor was almost similar to that of the adjacent sound dentin. SEM analysis revealed an extremely rough or irregular surface, and there remained a minimal debris-like smear layer; most of the dentinal tubules were opened. The results indicated that Carisolv does not produce any adverse side effects on dentinal compositions of the treated cavities. The possibility of remaining residual softened dentin was also minimal in this study.     

Detection of occlusal carious lesions

The purpose of this study was to determine the sensitivity and the specificity of detecting the presence and extent of occlusal carious lesions using traditional examination techniques performed by three experienced restorative dentists and a laser fluorescence-measuring device (DIAGNOdent) on 100 extracted third maxillary and mandibular molars. The extracted teeth were selected to ensure presence of questionable occlusal caries and intact occlusal surfaces. The results revealed that the DIAGNOdent demonstrated a higher sensitivity (94%) compared to the clinicians' consensus (82%) but a lower specificity. This study also indicated that higher values of the DIAGNOdent do not appear to correlate well with the depth of the carious lesion in the dentin (r = 0.3809) as measured by a caries-detecting dye.     

A follow-up study of the use of DIAGNOdent for monitoring fissure caries in children

OBJECTIVES: The aim of this study was to evaluate the utility of the laser fluorescence device DIAGNOdent for monitoring occlusal caries longitudinally as part of a routine dental check-up in a public dental clinic. METHODS: Children aged 7-8 and 13-14 years at baseline participated in the study. As part of two consecutive dental check-ups with a mean interval of 1,19, years, 423 permanent molars and 315 primary molars in 81 children were examined visually and using DIAGNOdent by one dentist. In teeth where, as judged by visual examination, caries had emerged or progressed during the follow-up, the DIAGNOdent values had increased significantly from the baseline. RESULTS: In permanent teeth with a change in visual score from sound to enamel or dentin caries, the mean DIAGNOdent value increased from 24 to 37 and in primary teeth from 8 to 40. The increase in DIANGOdent values correlated positively with the increase in visual score. The mean DIAGNOdent value at baseline was significantly higher in teeth that became carious than in those that remained sound during the follow-up. For permanent teeth with a visual reversal from inactive or active enamel caries to a sound surface, the mean DIAGNOdent value decreased from 36 to 24. CONCLUSIONS: These results suggest that DIAGNOdent is useful in monitoring occlusal caries in both permanent and primary molars.     

Occlusal caries detection and quantification by DIAGNOdent and Electronic Caries Monitor: in vitro comparison

The Electronic Caries Monitor (ECM) and the recently introduced laser-based KaVo DIAGNOdent have been developed as clinical diagnostic aids in the detection and quantification of occlusal carious lesions. The aim of this in vitro study was to compare their reproducibility and validity. The ability of DIAGNOdent to retrieve sites of occlusal carious lesions without reference to photographs or drawings from previous assessments was also tested. The material comprised 87 premolar teeth: the occlusal surfaces were sound or exhibited non-cavity carious lesions of varying severity. All were photographed and measured by DIAGNOdent and ECM on 2 occasions, 2 weeks apart. The teeth were then sectioned into 300 microm thick slices. Two observers independently classified the sections according to the histopathology, into 5 categories, ranging from sound to dentinal caries in the inner part of the dentin. Statistical analysis comprised intra-class correlation coefficients (ICC) to test reproducibility and regression analysis of validity. Sensitivity and specificity were also calculated for detection of D3 lesions for both devices. DIAGNOdent recorded maximum readings at identical sites on both occasions in 89% of the teeth. The ICC for readings on 2 separate occasions was 0.97 for DIAGNOdent and 0.71 for ECM. The correlations with histology were r = 0.93 and 0.83, for DIAGNOdent and ECM, respectively. For detection of D3 lesions, the sensitivity and specificity were 0.8 and 1 for DIAGNOdent and 0.75 and 0.88 for ECM. In this in vitro study, DIAGNOdent was superior to ECM for occlusal caries detection.