Comparison of natural and artificial root caries lesions using microcomputed tomography and microhardness test.

BACKGROUND: This study compared natural root caries lesions with artificial root caries lesions prepared with one of the two demineralising solutions. METHODS: Twelve natural root caries lesions on upper incisors and 24 artificial root lesions were prepared on sound root surfaces using 50 mM acetic acid, 1.5 mM CaCl2 , 0.9 mM KH2 PO4 at pH 5.0 or 80 mL/L Noverite K-702 polyacrylate solution, 500 mg/L hydroxyapatite, 0.1 mol/L lactic acid at pH 4.8 (n = 12/group) for 96 hours. Lesions were scanned using micro-CT. Inciso-gingival oriented images were analysed and mineral density calculated at 7.5 µm increments from the surface to 225-µm deep. Sectioned lesions were analysed by Knoop microhardness up to 250 µm from the lesion surface. Data were analysed by the Dunn's test with Bonferroni correction. RESULTS: Natural and artificial lesion mean mineral densities were not statistically different (P > 0.05). Mineral density from the surface to 75 µm was greater in natural lesions and from 150 to 225 µm was greater in artificial lesions (P < 0.05). Microhardness values were statistically higher in artificial lesions (P < 0.05); no difference was found among artificial lesions produced by the two solutions (P > 0.05). Mineral density and microhardness of natural and artificial root caries are different from each other. A greater mineralized surface layer existed on natural lesions.

Laser fluorescence is a predictor of lesion depth in non-cavitated root carious lesions - an in vitro study.

BACKGROUND: This in vitro study was designed to compare the assessment of carious root surfaces using laser fluorescence or visual assessment and µCT. METHODS: A total of 107 extracted human teeth were included in the study. For the subsequent assessment, a clinical evaluation according to Ekstrand and Nyvad criteria, laser fluorescence measurements (DIAGNOdent-Pen©), and µCT imaging (Bruker Skyscan 1172) of the included root surfaces were performed. For cavitated lesions, the surface was reconstructed on µCT. Target parameters were: clinical appearance, laser fluorescence reading (0-99), and lesion depth in µm (µCT). The statistical analysis included chi² and Spearman-Rho tests. RESULTS: Laser fluorescence values were significantly higher (p < 0.01) in leathery non-cavitated (median [IQR]: 73.50 [48.00]) and cavitated (88.50 [29.00]) surfaces than in hard intact surfaces (7.00 [35.00]). In addition, laser fluorescence values showed a significant correlation with lesion depth for non-cavitated surfaces (0.750; p < 0.01). Further statistically significant correlations were not detectable. Regression analysis showed that the laser fluorescence values increased with increasing demineralization depth (ß: 0.648, CI95: 0.631-1.053; p < 0.01). CONCLUSION: Laser fluorescence measured by DIAGNOdent© is a predictor for the depth of demineralization in carious root caries lesions with intact surfaces. Considering the limitations of this in vitro study, laser fluorescence is suitable for assessing the depth extent of (non-cavitated) root caries lesions and is a tool for clinical diagnosing and assessing the course of lesion development.

Evaluation of quantitative light-induced fluorescence to assess lesion depth in cavitated and non-cavitated root caries lesions - An in vitro study.

BACKGROUND: This in vitro study aimed to assess carious lesions on root surfaces using quantitative light-induced fluorescence (QLF) and to compare the readings with axial lesion depth on µCT. METHODS: The root surfaces of 107 extracted human teeth were included after visual-tactile inspection. For further analysis, the following parameters were assessed: clinical findings (non-cavitated: leathery or hard, cavitated), QLF- (QLF-D Biluminator 2+), and µCT-images (Bruker Skyscan 1172). The shape of the undamaged tooth surface of the cavitated lesions was virtually re-constructed during µCT analysis. Clinical surface texture,% fluorescence loss, and lesion depth (µCT) were determined. STATISTICAL ANALYSIS: chi²-test, Spearman-Rho test, regression analysis. RESULTS: ∆F was significantly lower in non-cavitated leathery (-50.37 ± 15.10) and cavitated (-61.23 ± 9.92) compared to non-cavitated surfaces with a hard texture (-17.04 ± 16.10, p < 0.01). For non-cavitated surfaces, a negative correlation was observed between ∆F and lesion depth in µCT images regardless of texture (-0.748, p < 0.01). Regression analysis revealed that ∆F predicted lesion depth in µCT for non-cavitated surfaces (ß: 0.703, CI95: 0.67--0.43, p < 0.01). CONCLUSION: The percentage of fluorescence loss (∆F) in QLF predicted lesion depth of non-cavitated demineralized root surfaces. Therefore, QLF can be recommended for estimating the lesion depth of carious root lesions and seems to expand the possibilities of follow-up and lesion monitoring, especially for non-cavitated surfaces.

Thermal Imaging of Root Caries In Vivo.

Improved methods are needed to assess the structure and activity of lesions on root surfaces in order to improve clinical decision making. Conventional visual and tactile methods for assessing lesion activity are not reliable, and the clinician is often unable to evaluate if the lesion is progressing or has remineralized. An important marker of an arrested lesion is a highly mineralized surface zone that forms when mineral is deposited in the outer layer of the lesion. In vitro studies have shown that a mineralized surface zone influences the kinetics of water evaporation and the surface temperature while drying. Temperature changes can be monitored by measuring the thermal emission with thermal imaging. Studies have also shown that the depth and severity of demineralization and the thickness of the highly mineralized transparent surface zone on arrested lesions can be measured nondestructively with optical coherence tomography (OCT). Thermal imaging at 8-µm to 13-µm wavelengths was completed on 30 test subjects with a suspected active root caries lesion by monitoring thermal emission from the tooth surfaces during 30 s of air drying. Lesions were also evaluated using cross-polarization OCT (CP-OCT) during lesion dehydration to identify transparent surface zones indicative of arrested lesions and determine if shrinkage occurred during drying. The overall thermal emission recorded during drying was significantly different (P < 0.001) when comparing sound tooth surfaces, lesion areas identified as arrested, and lesion areas identified as active, demonstrating that thermal imaging is a promising approach for the clinical assessment of lesion activity on root surfaces. Ten of the lesions in this study had distinct areas with transparent surface zones that were visible in CP-OCT images. Shrinkage was detected with CP-OCT during drying for 12 lesions. This study confirms that these novel approaches for assessing lesion activity on root surfaces can be implemented in vivo.

Assessment of non-cavitated root caries lesions by quantitative light-induced fluorescence-An in vivo feasibility study.

OBJECTIVES: To evaluate the reproducibility of quantitative light-induced fluorescence (QLF) for the detection and assessment of demineralization states of non-cavitated root surfaces and to determine the correlation between visual inspection and QLF-analysis. METHODS: 46 exposed non-cavitated root surfaces of 12 participants were classified in three scores: sound (0), lesion ≤ 5 mm (1a), lesion > 5 mm in diameter (1b). Three examiners imaged every root surface three times using QLF (QRayCam) and measured fluorescence loss (ΔF) and lesion volume (ΔQ). The QLF-images were analyzed by three examiners. The intra- and interexaminer reproducibilities were calculated (intraclass correlation coefficient, ICC). The correlation between the scores of root caries and QLF-analysis was determined (rank correlation coefficient, Spearman-Rho ρ). RESULTS: Intra- and interexaminer reproducibility (ICC) was 0.98 and 0.95 for ΔF, 0.94 and 0.91 for ΔQ, respectively. A significant correlation was observed between the scores and ΔF (ρ = -0.53, p < 0.01). CONCLUSION: QLF as a reproducible diagnostic tool enables non-invasive detection and differentiation of non-cavitated root caries lesions on root surfaces in vivo. It can be recommended in addition to the clinical evaluation for prospective follow-up examinations of demineralization states of exposed root surfaces.

Measurement of the shrinkage of natural and simulated lesions on root surfaces using CP-OCT.

OBJECTIVES: Demineralized root dentin and cementum is made up of mostly collagen that shrinks significantly upon dehydration or drying with air. During remineralization mineral is deposited on the outside of the lesion creating a highly mineralized surface layer that inhibits diffusion, arrests the lesion and prevents shrinkage. Previous studies suggest that active root caries lesions manifest shrinkage, while arrested lesions no longer manifest shrinkage upon dehydration. The purpose of this study was to demonstrate that the shrinkage of root caries lesions can be monitored during dehydration using an optical coherence tomography probe suitable for clinical use. METHODS: In this in vitro study the shrinkage of simulated and natural root caries lesions on extracted teeth was measured using a cross polarization optical coherence tomography (CP-OCT) system and a 3D printed appliance with an integrated air nozzle suitable for clinical use. Two methods were employed to assess shrinkage, changes in the position of the lesion surface and changes in the thickness of the lesion. RESULTS: CP-OCT was successful in measuring a significant (P < 0.05) contraction of the lesion surface, significant decrease in the lesion thickness and increase in the reflectivity per micron upon drying natural lesions on extracted teeth. CONCLUSIONS: In this preclinical study, we have demonstrated that a CP-OCT handpiece modified for infection control with an attached air nozzle suitable for in vivo use can be used to monitor the shrinkage of root caries lesions. In addition, we have developed a new approach to measuring lesion shrinkage with OCT, namely monitoring changes in the lesion thickness as opposed to the position of the lesion surface, that does not require an initial reference position and is more easily implemented in vivo.

Microcomputed Tomography Evaluation of Root Dentin Caries Prevention by Topical Fluorides and Potassium Iodide.

The mineral content of dental hard tissues has traditionally been measured by destructive tests such as transverse microradiography. Microfocus X-ray computed tomography (micro CT) has enabled non-destructive 3D assessment of tooth demineralization. This study compared the preventive effects of silver diammine fluoride (SDF) and potassium iodide (KI) in comparison with fluoride varnish. SDF has been known to arrest caries but darkens the tooth. KI creates a precipitate with SDF that reduces the discoloration, but its effects on SDF efficacy in terms of preventing demineralization of at-risk root dentin surfaces is unknown. Bovine root dentin blocks were randomly distributed into four groups and subjected to a pretreatment in each group (n = 8); Control: deionized water (DIW); F-Varnish: 5% sodium fluoride varnish: 38% Saforide; SDF+KI: SDF followed by saturated solution of KI in DIW. The treated dentin was subjected to 8 cycles of demineralization (pH 5) for 14 h and remineralization in artificial saliva (pH 7) for 10 h. Specimens were then scanned for 12 min using micro CT at 73 KV and 1012 µA with 8.3 µm resolution. The 3D images were analyzed in Amira software to calculate lesion depth (LD), surface layer mineral density (SL) and mineral loss (ΔZ) for each specimen. One-way ANOVA with Bonferroni posthoc showed that there was a statistically significant difference between Control and all three other groups for all parameters (P < 0.001), however, there was no statistical difference among F-Varnish, SDF and SDF+KI (P > 0.05). Single application of F-Varnish, SDF and SDF+KI showed comparable preventive effects against root dentin demineralization. Application of KI did not affect anti-demineralization properties of SDF in this study. Micro CT is a quick and effective method for objective and high-resolution characterization of dentin caries lesions.

Effects of silver diamine fluoride/potassium iodide on artificial root caries lesions with adjunctive application of proanthocyanidin.

Treatment of carious root surfaces remains challenging due to the complex pathological processes and difficulty in restoring the original structure of root dentine. Current treatments targeting the de-/re-mineralisation processes are not entirely satisfactory in terms of the protection of the dentinal organic matrix and the highly organised structure of dentine. In this in vitro study, a cross-linking agent - proanthocyanidin (PA) was used in conjunction with a fluoride-based treatment - silver diamine fluoride/potassium iodide (SDF/KI) to putatively stabilise the organic dentinal framework as well as strengthen the collagen-mineral phase interaction. The effectiveness of this strategy was evaluated 24 h after application in terms of the distribution of ion uptake and microstructure of dentine after treatment as well as analysis of the nano-mechanical properties using a dynamic behaviour model. Results showed that individual use of SDF/KI significantly improved the surface microhardness and integrated mineral density (Z) up to 60 µm depth and the recovery of creep behaviour of demineralised dentine in the surface area compared to that treated with deionised distilled water (DDW). The combined treatment of PA and SDF/KI achieved a more homogenous mineral distribution throughout the lesions than SDF/KI alone; a more significant incremental increase in surface microhardness and Z was observed. Specifically, a superior effect on the subsurface area occurred with PA + SDF/KI, with significant improvements in microhardness, elastic modulus and recovery of creep behaviour of the demineralised dentine. Application of SDF/KI induced small discrete crystal formation distributed over the dentine surface and PA contributed to the formation of slit-shaped orifices of the dentinal tubules that were partially occluded. STATEMENT OF SIGNIFICANCE: Demographic transitions and improved oral health behaviour have resulted in increased tooth retention in elderly people. As a consequence, the risk of root dentine caries is increasing due to the age-associated gingival recession and the related frequent exposure of cervical root dentine. Root caries is difficult to repair because of the complex aetiology and dentine structure. The recovery of dentine quality depends not only on reincorporation of minerals but also an intact dentinal organic matrix and the organic-inorganic interfacial structure, which contribute to the biomechanics of dentine. With the capability of dentine modification, cross-linking agents were applied with a fluoride regimen, which improved its treatment efficacy of root caries regarding the distribution of ion uptake and recovery of dentine biomechanics.

Assessment of root caries under wet and dry conditions using swept-source optical coherence tomography (SS-OCT).

The purpose of this study was to compare optical properties of root caries under two observing conditions using swept-source optical coherence tomography (SS-OCT). In vitro and natural root caries were observed by SS-OCT under wet and dry conditions, followed by confocal laser scanning microscope (CLSM) and transverse microradiography (TMR). Signal intensity (SI), distance between SI peaks (SI-distance) and optical lesion depth were obtained from OCT. Lesion depth was measured from CLSM; lesion depth (LDTMR) and mineral loss (ML) were obtained from TMR. In vitro root caries under wet and dry conditions showed different OCT images and SI patterns. Lesion depth of OCT and that of CLSM, SI-distance and LDTMR, LDTMR and ML significantly correlated. Under dry conditions, half natural root caries showed similar OCT images and SI patterns as in vitro root caries. The base of demineralized dentin could be detected more clearly under dry conditions than under wet conditions.

Cross-polarization reflectance imaging of root caries and dental calculus on extracted teeth at wavelengths from 400 to 2350 nm.

The identification of root caries and calculus on tooth roots is of increasing importance with our aging population. Exposed root surfaces are often impacted by erosion, abrasion, calculus and staining which can make the identification and management of caries challenging. Identification of dental calculus on root surfaces and verification of its removal is also important for patient education and to decrease susceptibility to caries and periodontal disease. The objective of this study was to determine how the contrast of root caries lesions and dental calculus varies with wavelength in the visible to near-infrared. The contrast of suspected root caries lesions and dental calculus on 30 extracted teeth was measured using cross-polarization reflectance measurements at wavelengths from 400 to 2350 nm. Significantly higher (P < 0.05) lesion contrast was measured at wavelengths greater than 1460 nm. Stains interfered significantly at wavelengths less than 850 nm yielding non-diagnostic contrast for root caries lesions. We postulate that the high absorption of water at longer wavelengths reduced the light scattering from the surrounding and underlying normal dentin, thus increasing the lesion contrast. This study indicates that wavelengths beyond 1400 nm are advantageous for imaging calculus and caries lesions on root surfaces due to the high contrast and lack of interference from stain.

Comparison of efficacy of dental varnish containing fluoride either with CPP-ACP or bioglass on root caries: Ex vivo study.

OBJECTIVES: To compare the efficacy of fluoride varnishes either casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) or bioglass particles on the severity index of root caries. METHODS: Visual-tactile assessments including lesion hardness was carried out to categorise the severity index of 80 extracted teeth with primary root caries. These teeth were randomly divided into four groups; CPP-ACP and fluoride, bioglass and fluoride, fluoride only, and no treatment. Standardised toothbrushing using a dentifrice containing 1450 ppm fluoride was carried out twice a day for all groups. All samples were stored in remineralising solution at 37°C for 45 days. Visual-tactile assessments were carried out at baseline, and after 45 days. Surface roughness measurements (Ra) were performed at baseline and after 7, 14, 30 and 45 days. X-ray Microtomography was performed at the baseline and after 45 days for three samples from each group to quantify the change in mineral contents in the lesion area. RESULTS: The Visual-tactile assessment results showed a reduction in the severity index of root caries, being 20% in CPP-ACP and fluoride, 100% in bioglass and fluoride, 80% in fluoride only, and 60% in non-varnish (toothbrushing only). Non-significant change in surface roughness was observed in all groups. X-ray Microtomography assessment showed a highly significant increase in the mineral deposition in all cases (p > .001). CONCLUSION: The combination of bioglass with fluoride has a potentially superior effect than either CPP-ACP with fluoride or fluoride only to reverse and arrest the root caries in a laboratory setting. CLINICAL SIGNIFICANCE: The combination of bioglass particles and fluoride formulation is likely to have a significant impact in reversing and arresting root caries in a minimally invasive approach. However, randomised controlled double-blinded clinical trials are required to translate these results into clinical practice.

Relationship Between Third Mandibular Molar Angulation and Distal Cervical Caries in the Second Molar.

Third lower molar partially erupted is commonly encountered in dental practice. This situation challenges clinicians with the dilemma whether to remove or to monitor it, because this molar can cause pathology of the adjacent second molar. The aim of this retrospective study is to evaluate the relationship between third mandibular molar and distal cervical caries in second molar. This retrospective study analyzed 55 digital orthopantograms of adult patients and a total number of 95 mandibular third molars were assessed for eruption status, angulation, radiographic evidence of caries or restoration in the mandibular third molar, and radiographic evidence of caries or restoration in the distal surface of the mandibular second molar. The distal cervical caries in second molar is associated with fully erupted and partially erupted wisdom molar in horizontal, mesioangular and vertical position and less with presence of caries in third molar. There are caries lesions in distal second molars in mesioangular position when adjacent third molar is caries free.

Starch Combined with Sucrose Provokes Greater Root Dentine Demineralization than Sucrose Alone.

Since there is no consensus about whether starch increases the cariogenic potential of sucrose, we used a validated 3-species biofilm model to evaluate if starch combined with sucrose provokes higher root dentine demineralization than sucrose alone. Biofilms (n = 18) composed by Streptococcus mutans (the most cariogenic bacteria), Actinomces naeslundii (which has amylolytic activity), and Streptococcus gordonii (which binds salivary amylase) were formed on root dentine slabs under exposure 8 ×/day to one of the following treatments: 0.9% NaCl, 1% starch, 10% sucrose, or a combination of 1% starch and 10% sucrose. Before each treatment, biofilms were pretreated with human whole saliva for 1 min. The pH of the culture medium was measured daily as an indicator of biofilm acidogenicity. After 96 h of growth, the biofilms were collected, and the biomass, bacteria viability, and polysaccharides were analyzed. Dentine demineralization was assessed by surface hardness loss (% SHL). Biofilm bioarchitecture was analyzed using confocal laser scanning microscopy. Treatment with a starch and sucrose combination provoked higher (p = 0.01) dentine demineralization than sucrose alone (% SHL = 53.2 ± 7.0 vs. 43.2 ± 8.7). This was supported by lower pH values (p = 0.007) of the culture medium after daily exposure to the starch and sucrose combination compared with sucrose (4.89 ± 0.29 vs. 5.19 ± 0.32). Microbiological and biochemical findings did not differ between biofilms treated with the combination of starch and sucrose and sucrose alone (p > 0.05). Our findings give support to the hypothesis that a starch and sucrose combination is more cariogenic for root dentine than sucrose alone.

Remineralization Potential of Mints Containing Bioactive Agents in Artificially Induced Root Caries.

This study investigated the remineralization effect of experimental mint formulations containing bioactive agents (xylitol; green tea extract, GT; and amorphous calcium phosphate, ACP) in the progression of artificially induced root caries. Root caries lesions were induced by demineralization solution (pH 4.6; 96 h; 37°C). The lesions were treated with mint A, mint B, mint C, xylitol, GT, ACP, or remineralization solution (RS; negative control). Specimens were pH-cycled through treatments (5×/day; 3 min) and 6 cycles of acidic (pH 5.0; 30 min) and neutral (pH 7.0; 10 min) buffers for 8 days. Bacterial collagenase (Clostridium histolyticum) was used overnight to simulate proteolytic challenge. Caries depth and porosity as well as mineral density were estimated using fluorescence microscopy (n = 15) and microcomputed tomography (n = 6). Analysis of variance (ANOVA, α = 0.05) showed no statistically significant difference in caries depth among all groups (p = 0.172). The highest fluorescence intensity decrease was observed for GT followed by mint C, with no significant difference between them (p = 0.868). There were significant differences among GT and mints A, B, and C when compared to RS (p < 0.001). No statistically significant differences in fluorescence intensity were observed among ACP, xylitol, and RS (p > 0.05). The mineral density of the lesions in GT, mints A, B, and C, and ACP was statistically similar (p > 0.05) and significantly higher than that in RS (p < 0.05). No significant difference was observed between xylitol and RS (p = 0.728). The experimental mints showed remineralization action on artificial root caries, and GT was found to be the main active ingredient in the investigated formulations.

Use of PIXE/PIGE for sequential Ca and F measurements in root carious model.

The progress of caries has conventionally been evaluated by checking changes in mineral density using transverse microradiography (TMR). Recent advances have seen development of a new measurement system, using in-air micro proton induced X-ray/gamma-ray emission (PIXE/PIGE). PIXE/PIGE enables analysis of distributions and concentrations of multiple mineral elements in a carious lesion. The aim of this study was to evaluate the effectiveness of PIXE/PIGE for investigating the development of root caries. In summary, we successfully established a multi-elemental sequential measuring method using in-air micro-PIXE/PIGE to identify the dynamic distributions and concentrations of Ca and F in human root dentin. The PIXE/PIGE potentially offers a useful advantageous technique for studying carious development by using as a combination with conventional techniques such as TMR and Micro-computed tomography (µCT).

Activity assessment of root caries lesions with thermal and near-IR imaging methods.

The purpose of this study was to evaluate thermal and near-infrared (NIR) reflectance imaging methods for the assessment of the activity of root caries lesions. In addition, changes in the lesion structure were monitored with polarization sensitive optical coherence tomography (PS-OCT). Artificial bovine and natural root caries lesions were imaged with PS-OCT, and their dehydration rate was measured with thermal and NIR cameras. The lesion activity of the natural root caries samples was also assessed by two clinicians by conventional means according to ICDAS II guidelines. The thickness of the highly mineralized transparent surface layer measured using PS-OCT increased and the area enclosed by the time-temperature curve, ΔQ, measured with thermal imaging decreased significantly with longer periods of remineralization in simulated dentin lesions, but the NIR reflectance intensity differences, ΔI, failed to show any significant relationship with the degree of remineralization. The PS-OCT algorithm for the automated assessment of remineralization successfully detected the highly mineralized surface layer on both natural and simulated lesions. Thermal imaging provided the most accurate diagnosis of root caries lesion activity. These results demonstrate that thermal imaging and PS-OCT may be ideally suited for the nondestructive root caries lesion activity during a clinical examination.

Evaluation of a new hardness tester (Cariotester): Comparison with transverse microradiography for assessing the inhibitory effect of fluoride application on bovine root dentin demineralization.

The objective of this study was to investigate the correlation between CT depth, indentation depth determined by a new hardness tester (Cariotester), and the transverse microradiography (TMR) parameters, i.e., lesion depth and mineral loss. For that purpose, this study evaluated the feasibility of using Cariotester as a root caries diagnostic system and capability of Cariotester to detect effect of fluoride application on inhibiting dentin demineralization. Fluorides were applied to bovine root dentin specimens, which were subsequently demineralized for 1-21 days and then CT depth and TMR parameters were assessed. There were significant correlations between CT depth and TMR parameters in fluoride and non-fluoride groups. There were significant differences between fluoride and non-fluoride groups for CT depth and TMR parameters respectively. Current results suggested that Cariotester may be capable of providing an objective evaluation of root caries progression and the fluoride effect on inhibiting dentin demineralization.

[Method of root canal retreatment using computer simulation].

The paper describes a method of root canal retreatment that enables by means of CT data, laser surface scanning of teeth and a number of software to create plastic templates making possible successful retreatment with minimal risk of complications. The effectiveness of the method was evaluated in vitro on 10 extracted teeth. Application of the method in clinical practice enables the highest degree of accuracy and security of the procedure.

In vitro detection of secondary caries associated with composite restorations on approximal surfaces using laser fluorescence.

This study evaluated the performance of the DIAGNOdent pen laser fluorescence device (LFpen) in comparison with visual examination (VE), bitewing radiographs (BW) and visual examination combined with bitewing radiographs (VEBW) in detecting secondary approximal caries associated with composite restorations. In total, 60 approximal surfaces from 43 permanent molars with composite restorations were assessed twice by two examiners using the LFpen, VE, BW and VEBW. After histological preparation and hardness measurements, the sample was assigned to either a crown or root caries group, depending on the location of the lesions as the gold standard. For crown caries at D1, the highest values of specificity and sensitivity were observed for the LFpen at a cutoff value of 18 (1.00) and for the VEBW (0.89). At D3 (cutoff of 30), the LFpen showed the highest values of sensitivity and specificity. For root caries, the LFpen and VEBW showed the highest values of specificity (0.54), sensitivity (0.81) and accuracy (0.69). The Spearman rank correlation coefficients for crown/root caries with histology were 0.54/0.37 (LFpen), 0.29/0.10 (BW), 0.29/0.18 (VE) and 0.23/0.37 (VEBW). For the LFpen, the ICC varied from 0.80 (interexaminer) to 0.97 (intraexaminer B); the kappa value was 0.19 for BW and 0.35 for VE (interexaminer). Intraexaminer kappa values for BW were 0.25 (A) and 0.29 (B), and those for VE were 0.31 (A) and 0.32 (B). The LFpen device exhibited a performance comparable to that of conventional methods but with higher interexaminer reproducibility. Therefore, the LFpen should be considered an auxiliary method for the detection of secondary approximal caries associated with composite restorations.