Occlusal caries detection and monitoring using a 3D intraoral scanner system. An in vivo assessment

OBJECTIVE

To assess the agreement in detecting and monitoring occlusal caries over thirty months using conventional visual and radiographic assessment and an intraoral scanner system which supports automated caries scoring.

METHODS

Ninety-one young participants aged 12-19 years were included in the study. All occlusal surfaces were examined visually, radiographically (when indicated), and scanned with the TRIOS 4 intraoral scanner. TRIOS Patient Monitoring software (vers. 2.3, 3Shape TRIOS A/S, Denmark) was used for automated caries detection on the 3D digital models.

RESULTS

Fifty-five of the study participants were re-examined after 30-months. Significant differences regarding caries detection were found between the conventional methods and the automated caries scoring system (p < 0.01), with moderate positive percent agreement (49-61%) and high negative percent agreement (87-98%). All methods reported significant caries progression over the follow-up period (p < 0.01). However, the automated system showed significantly more caries progression than the other methods (p < 0.01).

CONCLUSIONS

The software for automated caries detection and classification showed moderate positive agreement and strong negative agreement with the conventional methods considering both the baseline and the follow-up assessments. The automated caries scoring system detected significantly fewer caries lesions and tended to underestimate the caries severity. All methods indicated significant caries progression over the follow-up period, while the automated system detected more caries progression.

CLINICAL SIGNIFICANCE

The TRIOS system supporting automated occlusal caries detection and classification can assist in detecting and monitoring occlusal caries on permanent teeth as a complementary tool to the conventional methods. However, the operator should be aware that the automated system shows a tendency to underestimate the caries presence and lesion severity.

Different Methods of Scan Alignment in Erosive Tooth Wear Measurements: An In Vitro Study

BACKGROUND

Model alignment in cases of erosive tooth wear can be challenging, and no method has been reported to outweigh the others.

METHODS

Extracted human teeth were mounted on two models and scanned at different times, from 1 h to 2 weeks, with an intraoral scanner (3Shape TRIOS 4) before and after immersion in Monster® energy drink and tap water. The scans were superimposed (3Shape TRIOS Patient Monitoring, Version 2.2.3.3, 3Shape A/S, Copengagen, Denmark). Best fit, best-fit tooth comparison, reference best fit using fillings, and palatal rugae as reference points were used for alignment. Surface profile differences were calculated in a cross-section view. The nonparametric Bland-Altman and Kruskal-Wallis tests were used.

RESULTS

First, statistically significant differences were marked after 4 days of immersion. The measurements obtained after 2 weeks of immersion were statistically significantly different from the measurements obtained at the different time points until 1 week. No statistically significant differences (p < 0.05) were observed among the alignment methods at any time.

CONCLUSION

In comparison to the best-fit model, both palatal rugae and fillings can be used. The best-fit tooth comparison method is a reliable option; however, it should be used with caution in cases of major surface loss.

Caries Detection in Primary Teeth Using Intraoral Scanners Featuring Fluorescence: Protocol for a Diagnostic Agreement Study

BACKGROUND

Digital methods that enable early caries identification can streamline data collection in research and optimize dental examinations for young children. Intraoral scanners are devices used for creating 3D models of teeth in dentistry and are being rapidly adopted into clinical workflows. Integrating fluorescence technology into scanner hardware can support early caries detection. However, the performance of caries detection methods using 3D models featuring color and fluorescence in primary teeth is unknown.

OBJECTIVE

This study aims to assess the diagnostic agreement between visual examination (VE), on-screen assessment of 3D models in approximate natural colors with and without fluorescence, and application of an automated caries scoring system to the 3D models with fluorescence for caries detection in primary teeth.

METHODS

The study sample will be drawn from eligible participants in a randomized controlled trial at the Royal Children's Hospital, Melbourne, Australia, where a dental assessment was conducted, including VE using the International Caries Detection and Assessment System (ICDAS) and intraoral scan using the TRIOS 4 (3Shape TRIOS A/S). Participant clinical records will be collected, and all records meeting eligibility criteria will be subject to an on-screen assessment of 3D models by 4 dental practitioners. First, all primary tooth surfaces will be examined for caries based on 3D geometry and color, using a merged ICDAS index. Second, the on-screen assessment of 3D models will include fluorescence, where caries will be classified using a merged ICDAS index that has been modified to incorporate fluorescence criteria. After 4 weeks, all examiners will repeat the on-screen assessment for all 3D models. Finally, an automated caries scoring system will be used to classify caries on primary occlusal surfaces. The agreement in the total number of caries detected per person between methods will be assessed using a Bland-Altman analysis and intraclass correlation coefficients. At a tooth surface level, agreement between methods will be estimated using multilevel models to account for the clustering of dental data.

RESULTS

Automated caries scoring of 3D models was completed as of October 2023, with the publication of results expected by July 2024. On-screen assessment has commenced, with the expected completion of scoring and data analysis by March 2024. Results will be disseminated by the end of 2024.

CONCLUSIONS

The study outcomes may inform new practices that use digital models to facilitate dental assessments. Novel approaches that enable remote dental examination without compromising the accuracy of VE have wide applications in the research environment, clinical practice, and the provision of teledentistry.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12622001237774; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=384632.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51578.

Fluorescence and Near-Infrared Light for Detection of Secondary Caries: A Systematic Review

BACKGROUND

Early detection of secondary caries near dental restorations is essential to prevent further complications. This systematic review seeks to evaluate the sensitivity of fluorescence and near-infrared (NIR) imaging techniques for detecting secondary caries and to provide insight into their clinical utility.

METHODS

A comprehensive search strategy was used to select studies from seven databases, emphasizing diagnostic accuracy studies of secondary caries detection using fluorescence and NIR imaging techniques. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) instrument assessed bias risk and practicality. Two evaluators performed data extraction, screening, and quality assessment independently.

RESULTS

From 3110 initial recordings, nine studies were selected for full-text analysis. Wide variations in sensitivity (SE) and specificity (SP) values were reported across the studies. These studies exhibited variable SE and SP values, and the findings highlighted the importance of method selection based on clinical context. This systematic review underlines the potential for fluorescence and NIR imaging to detect secondary caries. However, results from different studies vary, indicating the need to consider additional variables such as restoration materials.

CONCLUSIONS

Although these technologies exhibit potential for detecting caries, our research underscores the complex procedure of identifying secondary caries lesions. It is a continuous necessity for progress in dental diagnostics to promptly identify secondary caries lesions, particularly those in proximity to tooth-colored ones.

Occlusal caries detection on 3D models obtained with an intraoral scanner. A validation study

OBJECTIVES

To evaluate the diagnostic performance of visual caries assessment on 3D dental models obtained using an intraoral scanner and to compare it with the performance of the clinical visual inspection.

METHODS

Fifty-three permanent posterior teeth scheduled for extraction were randomly selected and included in this study. One to three independent examination sites on the occlusal surface of each tooth were clinically inspected using International Caries Detection and Assessment System (ICDAS) criteria. Afterwards, the examined teeth were scanned intraorally with a 3D intraoral scanner (TRIOS 4, 3Shape TRIOS A/S, Copenhagen, Denmark) using white and blue-violet light (415 nm wavelength) to capture the colour and fluorescence signal from the tissues. Six months after the clinical examination, the same examiner conducted the on-screen assessment of the obtained 3D digital dental models at the selected examination sites using modified ICDAS criteria. Both tooth colour and fluorescence texture with high resolution were assessed. Lastly, an independent examiner conducted the histological examination of all teeth after extraction. Using histology as the reference test, Sensitivity (SE), Specificity (SP), Accuracy (ACC), area under the Receiver Operating Characteristic (ROC) curve, and Spearman's correlation coefficient were calculated for the clinical and on-screen ICDAS assessments.

RESULTS

The ACC values of the evaluated methods varied between 0.59-0.79 for initial caries lesions and 0.77-0.99 for moderate-extensive caries lesions. Apart from SE values corresponding to caries in the inner half of enamel, no significant difference was observed between clinical visual inspection and on-screen assessment. In addition, no difference was found in the assessment of 3D models with tooth colour alone or supplemented with fluorescence for all the evaluated diagnostic measures.

CONCLUSIONS

On-screen visual assessment of 3D digital dental models with tooth colour or fluorescence showed a similar diagnostic performance to the clinical visual inspection when detecting and classifying occlusal caries lesions on permanent teeth.

CLINICAL SIGNIFICANCE

3D intraoral scanning can aid the detection and classification of occlusal caries as part of patient screening and can potentially be used in remote caries assessment for clinical and research purposes.

Secondary caries detection and treatment decision according to two criteria and the impact of three-dimensional intraoral scanner on gap evaluation

This study aimed to evaluate the in vitro performance in detecting caries around composite restorations in permanent posterior teeth and the impact of treatment decisions of two visual criteria: International Dental Federation (FDI) criteria and the Caries Associated with Restorations and Sealants (CARS) system. The correlation among secondary caries and the presence of gap measured with a three-dimensional (3D) intraoral scanner was also aimed. One hundred sixteen teeth were assessed by a trained and calibrated examiner according to the FDI criteria or CARS system. A second examiner measured the gap on the 3D models using specific software. The reference standard was the histological examination performed by a third examiner blind to the other evaluations. Other 30 extracted permanent teeth were used only to assess the reproducibility of the methods. The same random sample was selected for re-examination by all three methods, and there were seven days between the examinations. Unweighted and weighted kappa tests were conducted to assess intra-examiner reproducibility. Spearman's correlation coefficient (Rho) and 95% confidence intervals (95%CI) were calculated between the histological examination and scores obtained with FDI criteria, CARS system and treatment decisions. Spearman correlation between the visual and scanner evaluation with the reference standard was performed. Spearman's rank correlation analyses were conducted independently between the gap evaluated and measured by the visual inspection with the gap assessed using the scanner. The reproducibility of the visual score systems reached high values. Spearman's correlation coefficients (Rho; 95%CI) between the following variables versus histology were: FDI presence of caries (0.65; 0.53 to 0.74); CARS scores (0.65; 0.52 to 0.74); FDI treatment decision (0.46; 0.31 to 0.59); and CARS treatment decision (0.62; 0.49 to 0.72). Rho (95%CI) between histology and the gap assessment by the visual inspection was 0.59 (0.45 to 0.70), with the gap measurement by the visual inspection was 0.49 (0.33 to 0.62), and the gap measured by the scanner was 0.37 (0.18 to 0.53). Both visual criteria present similar performance in detecting caries. The correlation among treatment decisions is moderate for the FDI and CARS criteria, and both are moderately correlated with lesion depth, with a slight CARS superiority. However, visual examination presents better performance than the 3D intraoral scanner on gap size assessment.

Systematic review and meta-analysis of diagnostic studies of proximal surface caries

AIM

This systematic review and meta-analysis aimed to assess the diagnostic accuracy and reliability of commonly used caries detection methods for proximal caries diagnostics. Visual examination (VE), bitewing radiography (BWR), laser fluorescence (LF), and fibre-optic transillumination (FOTI) were considered in detail.

MATERIAL AND METHODS

PRISMA guidelines for the reporting of systematic reviews and meta-analyses were applied. The mnemonic PIRDS (problem, index test, reference test, diagnostic and study type) concept was used to guide the literature search. Next, studies that met the inclusion criteria were stepwise selected and evaluated for their quality with a risk of bias (RoB) assessment tool. Studies with low/moderate bias and sufficient reporting were considered for meta-analysis. The pooled sensitivity (SE), specificity (SP), diagnostic odds ratio (DOR), and area under the ROC curve (AUC) were calculated.

RESULTS

From 129 studies meeting the selection criteria, 31 in vitro studies and five clinical studies were finally included in the meta-analysis. The AUC values for in vitro VE amounted to 0.84 (caries detection) and 0.85 (dentin caries detection). BWR ranged in vitro from 0.55 to 0.82 (caries detection) and 0.81-0.92 (dentin caries detection). LF showed higher AUC values for overall caries detection (0.91) and dentin caries detection (0.83) than did other methods. Clinical data are limited.

CONCLUSION

The number of diagnostic studies with low/moderate RoB was found to be low and indicates a need for high-quality, well-designed caries diagnostic studies.

CLINICAL RELEVANCE

BWR and LF showed good diagnostic performance on proximal surfaces. However, because of the low number of includable clinical studies, these data should be interpreted with caution.

Intraoral scanner featuring transillumination for proximal caries detection. An in vitro validation study on permanent posterior teeth

OBJECTIVES

To assess the validity of an intraoral scanner system featuring near-infrared (NIR) transillumination to aid the detection of proximal caries lesions, and to compare the diagnostic performance of this system with that of conventional caries detection methods and with that of an intraoral camera featuring NIR transillumination (DIAGNOcam).

METHODS

Ninety-five permanent posterior teeth were examined using a prototype tip functioning with TRIOS 4 intraoral scanner system (3Shape TRIOS A/S, Denmark) and emitting NIR light, DIAGNOcam, and visual and radiographic examination employing ICDAS criteria. One or two approximal surfaces per tooth, sound or with caries lesions at different stages, were examined (N₁=158). Histological assessment was used as the reference standard.

RESULTS

All methods showed excellent intra-examiner reliability (κ_intra ≥0.80). Two independent examiners assessed the NIR images obtained with both devices. The first examiner, who obtained and assessed the images, showed improved diagnostic performance than the second examiner, who only had access to the images. The inter-examiner agreement between the two examiners assessing the NIR images was substantial (κ_inter 0.57-0.72). The intraoral scanner and DIAGNOcam showed similar diagnostic performance. Regarding initial caries lesions, the NIR image assessment resulted in equal or improved sensitivity (SE 0.50-0.89) compared to radiographic assessment (SE 0.49-0.51) and higher than visual examination (SE 0.28-0.39). Radiographic and NIR image assessment resulted in similar SE in detecting moderate-extensive dentin caries lesions (SE 0.59-0.70), while visual examination showed an inferior value (SE 0.30).

CONCLUSIONS

The intraoral scanner system featuring NIR transillumination and DIAGNOcam showed an overall good diagnostic performance. The conventional caries detection methods showed inferior sensitivity at initial caries lesion stages.

CLINICAL SIGNIFICANCE

Considering the promising diagnostic performance of the intraoral scanner featuring transillumination and the advantages offered by combining the NIR images with the 3D models of the teeth, this system has the potential to contribute towards more reliable caries detection and monitoring in clinical practice without the use of ionizing radiation.

Systematic review and meta-analysis of diagnostic methods for occlusal surface caries

AIM

This systematic review and meta-analysis aimed to assess the diagnostic performance of commonly used methods for occlusal caries diagnostics, such as visual examination (VE), bitewing radiography (BW) and laser fluorescence (LF), in relation to their ability to detect (dentin) caries under clinical and laboratory conditions.

MATERIALS AND METHODS

A systematic search of the literature was performed to identify studies meeting the inclusion criteria using the PIRDS concept (N = 1090). A risk of bias (RoB) assessment tool was used for quality evaluation. Reports with low/moderate RoB, well-matching thresholds for index and reference tests and appropriate reporting were included in the meta-analysis (N = 37; 29 in vivo/8 in vitro). The pooled sensitivity (SE), specificity (SP), diagnostic odds ratio (DOR) and areas under ROC curves (AUCs) were computed.

RESULTS

SP ranged from 0.50 (fibre-optic transillumination/caries detection level) to 0.97 (conventional BW/dentine detection level) in vitro. AUCs were typically higher for BW or LF than for VE. The highest AUC of 0.89 was observed for VE at the 1/3 dentin caries detection level; SE (0.70) was registered to be higher than SP (0.47) for VE at the caries detection level in vivo.

CONCLUSION

The number of included studies was found to be low. This underlines the need for high-quality caries diagnostic studies that further provide data in relation to multiple caries thresholds.

CLINICAL RELEVANCE

VE, BW and LF provide acceptable measures for their diagnostic performance on occlusal surfaces, but the results should be interpreted with caution due to the limited data in many categories.

Identifying and Avoiding Risk of Bias in Caries Diagnostic Studies

Caries diagnostic studies differ with respect to their design, included patients/tooth samples, use of diagnostic and reference methods, calibration, blinding and data reporting. Such heterogeneity makes comparisons between studies difficult and could represent a substantial risk of bias (RoB) when it is not identified. Therefore, the present report aims to describe the development and background of a RoB assessment tool for caries diagnostic studies. The expert group developed and agreed to use a RoB assessment tool during three workshops. Here, existing instruments (e.g., QUADAS 2 and the Joanna Briggs Institute Reviewers' Manual) influenced the hierarchy and phrasing of the signalling questions that were adapted to the specific dental purpose. The tailored RoB assessment tool that was created consists of 16 signalling questions that are organized in four domains. This tool considers the selection/spectrum bias (1), the bias of the index (2) and reference tests (3), and the bias of the study flow and data analysis (4) and can be downloaded from the journal website. This paper explores possible sources of heterogeneity and bias in caries diagnostic studies and summarizes the relevant methodological aspects.

Development of a Fluorescence-Based Caries Scoring System for an Intraoral Scanner: An in vitro Study

OBJECTIVES

To develop an automated fluorescence-based caries scoring system for an intraoral scanner and totest the performance of the system compared to state-of-the-art methods.

METHODS

Seventy-three permanent posterior teeth were scanned with a three-dimensional (3D) intraoral scanner prototype which emitted light at 415 nm. An overlay representing the fluorescence signal from the tissue was mapped onto 3D models of the teeth. Multiple examination sites (n = 139) on the occlusal surfaces were chosen, and their red and green fluorescence signal components were extracted. These components were used to calculate 4 mathematical functions upon which a caries scoring system for the scanner prototype could be based. Visual-tactile (International Caries Detection and Assessment System, ICDAS), radiographic (ICDAS), and histological assessments were conducted on the same examination sites.

RESULTS

Most index tests showed significant correlation with histology. The strongest correlation was observed for the visual-tactile examination (rs = 0.80) followed by the scanner supported by the caries classification function that quantifies the overall fluorescence compared to sound surfaces (rs = 0.78). Additionally, this function resulted in the highest intra-examiner reliability (κ = 0.964), and the highest sum of sensitivity (SE) and specificity (SP) (sum SE-SP: 1.60-1.84) at the 2 histological levels where the comparison with visual-tactile assessment was possible (κ = 0.886, sum SE-SP = 1.57-1.81) and at the 3 out of 4 histological levels where the comparison with radiographic assessment was possible (κ = 0.911, sum SE-SP = 1.37-1.78); the only exception was for the lesions in the outer third of dentin, where the radiographic assessment showed the highest sum SE-SP (1.78).

CONCLUSION

A fluorescence-based caries scoring system was developed for the intraoral scanner showing promising performance compared to state-of-the-art caries detection methods. The intraoral scanner accompanied by an automated caries scoring system may improve objective caries detection and increase the efficiency and effectiveness of oral examinations. Furthermore, this device has the potential to support reliable monitoring of early caries lesions.

Adhesion and marginal adaptation of a claimed bioactive, restorative material

Objectives: Adhesion and marginal adaptation of a claimed bioactive restorative material (ACTIVA BioACTIVE Restorative) to human teeth were compared with those of a resin-modified glass ionomer cement (Fuji II LC) and a control resin composite (Ceram X Mono). Material and Methods: Shear bond strength and marginal adaptation to enamel and dentine were assessed after no pretreatment of the hard tissues or after etching with phosphoric acid (ACTIVA BioACTIVE Restorative and Ceram X Mono) or polyacrylic acid (Fuji II LC). For ACTIVA BioACTIVE Restorative, the effect of applying a self-etch adhesive (Xeno Select, Dentsply Sirona) was also investigated. Data were analyzed using non-parametric tests (α = 0.05). Results: Bond strength and marginal adaptation in enamel and dentine were significantly different among the investigated materials (p<.05). Due to loss of restorations, it was not possible to measure bond strength of ACTIVA BioACTIVE Restorative if no pretreatment was performed or if dentine was etched; however, use of the self-etch adhesive resulted in similar bond strength as Ceram X Mono. Etching improved adhesion of Fuji II LC to enamel and dentine. Regarding marginal adaptation, ACTIVA BioACTIVE Restorative showed the highest wall-to-wall contraction to enamel in all pretreatment groups and the overall highest wall-to-wall contraction to dentine after etching. Due to loss of restorations, no marginal assessment was possible on cavities with margins in dentine when no pretreatment was used. The use of a self-etch adhesive with ACTIVA BioACTIVE Restorative resulted in similar adaptation to dentine compared to the other materials. Conclusion: The self-adhesive property of ACTIVA BioACTIVE Restorative is nonexistent.

Evaluation of marginal and internal fit of acrylic bridges using optical coherence tomography

BACKGROUND

The potential of non-invasive optical coherence tomography (OCT) as a tool for assessment of fit of indirect reconstructions is not fully explored.

OBJECTIVES

The objectives were to investigate the feasibility and validity of OCT, and to measure the internal and marginal fit of acrylic bridges fabricated using direct and indirect digitalisation.

METHODS

The accuracy of the employed swept source OCT (wavelength: 1310 nm) was assessed by comparing with an object with known dimensions. Validity was assessed by measuring an OCT measurements on replica, mimicking the cement film thickness, with stereomicroscopic measurements. The reconstructions were placed on the abutments without cementation. The internal and marginal fit of acrylic bridges from direct and indirect digitalisation techniques were then assessed by obtaining 5 OCT B-scans per abutment tooth at pre-defined positions located 250 μm apart. The marginal and internal cement gaps were measured using image-processing software (ImageJ). Mean and standard deviation were calculated for both groups and t test assuming unequal variances was carried out. The level of significance was defined at 0.05.

RESULTS

A strong linear correlation (r = 0.865) between OCT and stereomicroscopy was found. T test showed significantly (P < 0.01) better internal fit of bridges made from indirect digitalisation, but no difference in marginal fit.

CONCLUSION

OCT is a feasible and valid tool for investigating internal and marginal fit of acrylic dental reconstructions. Better internal fit was observed in bridges fabricated using the direct digitalisation technique. No difference in marginal fit was found between the two fabrication methods.