Proximal caries lesion detection using the Canary Caries Detection System: an in vitro study

Current Approaches to Diagnosis of Early Proximal Carious Lesion: A Literature Review

Integrating technological tools with clinical visual examination for caries detection and diagnosis can improve preventative measures in dentistry, resulting in decreased treatment expenses and reduced time and costs associated with testing potential anticaries agents. This article provides an overview of the conventional and new emerging modern technologies that can assist dental professionals in the early detection and diagnosis of dental caries. These technologies aid in assessing the progression of carious lesions and monitoring them quantitatively or qualitatively over time. Traditional techniques (visual, tactile, and radiographic) have limitations in diagnosing early proximal caries accurately. Novel methods like fluorescence and transillumination, as well as advanced tools like OCT (optical coherence tomography), laser fluorescence, and QLF (quantitative light-induced fluorescence), are effective for early caries detection. Optical methods like fluorescence and transillumination are particularly successful in identifying initial caries stages. Moreover, this review highlights the clinical relevance of these methods and discusses potential future technologies like terahertz imaging and artificial intelligence (AI)-based approaches.

Impact of angle on photothermal radiometry and modulated luminescence (PTR/LUM) value

OBJECTIVE

To evaluate the impact of scanning angles to detect/quantify non-cavitated caries by photothermal-radiometry and modulated-luminescence (PTR/LUM, Canary System) and to evaluate the association of PTR/LUM value with lesion depth (LD), including sound tissue thickness under the lesion (ST).

METHODS

Thirty human extracted premolars were selected based on micro-computed tomography [μ-CT: sound (n=12), lesions into outer-half of enamel (n=6), lesions into inner-half of enamel (n=6), lesions into outer one-third of dentine (n=6)]. Each tooth sample was scanned 90° directly contacted to the center of non-cavitated lesion or sound smooth surface, and tilted 10° and 20° in four directions: buccal/lingual/occlusal/cervical. The procedure was repeated 48 h later. Lesion depth and ST [ST=5000 µm (maximum PTR/LUM scanning depth)-LD] were measured at the same scanning direction on μ-CT images. Sensitivity, specificity, area under the Receiver Operating Characteristic curve (AUC), and intraclass correlation coefficients (ICC) for different scanning angles were calculated. Sensitivity was further evaluated based on lesion extensions. Relationships between PTR/LUM value and lesion depth, and between PTR/LUM value and LD/ST-Ratio were evaluated.

RESULTS

PTR/LUM value showed significant differences among scanning angles. Overall sensitivity (78%-89%), specificity (66%-87%), AUC (0.86-0.92) and ICC (0.89-0.99), sensitivity based on lesion extensions presented no significant differences among angles. PTR/LUM value showed moderate correlations (0.56-0.74) with deepest lesion depth and LD/ST-Ratios.

CONCLUSION

The scanning angle within 20° increments might impact PTR/LUM value statistically; however, it did not affect PTR/LUM detection performance. PTR/LUM values were positively correlated with non-cavitated lesion depth, and not affected by sound tissue thickness under the lesion.

CLINICAL SIGNIFICANCE

Clinically, it is challenging to measure/scan at the same location and same angle longitudinally, however, it is important to standardize these parameters. Scanning within 20° deviation from perpendicular did not affect detection performance of PTR/LUM, and PTR/LUM value showed positive moderate correlation with caries depth.

Quantitative Measurements of the Depth of Enamel Demineralization before and after Bleach: An In Vitro Study

Objective

This study is aimed at determining two main points. First, if the Canary System™ (CS), initially used to assess caries, can measure a decalcification depth of bleached enamel quantitatively, and second, whether or not whitening has a harmful effect on enamel. This device can be considered a useful tool in the clinical assessment of the progression of demineralization after bleaching.

Materials and Methods

This study collected sixty human premolars that are in a good state recently extracted for orthodontic reason. To properly disinfect and preserve the premolars, they were stored in a saline solution and later in distilled water for a period of two weeks to allow the premolars to rehydrate. Later, 24 hours before the experiment, the premolars were introduced into a solution of artificial saliva to acquire back their minerals. The mineral content of the teeth was measured by the Canary System™ before bleaching. The teeth were bleached with 30% hydrogen peroxide (fläsh HP 30%), 30 min per week and for 3 consecutive weeks to simulate the conditions of strong bleaching in the clinic. The extent of demineralized enamel was measured by the Canary System™ at three points on the enamel surface of each tooth. The data were averaged for each application of the bleaching product. The demineralization extent of the teeth was measured by the Canary System™ before and after bleaching. The significance level was set at 0.05, and SPSS version 26 was used. The data were analyzed by using Wilcoxon's and Student's tests.

Results

Mineral loss occurred after the first bleaching session; the Canary System™ detected a decalcification in the first bleaching session (532 ± 322 μm) compared to the other sessions (p ≤ 0.05), while no significant change was detected between the second and the third sessions (p > 0.05).

Conclusion

Based on the findings of the present study, under in vitro conditions, it was possible to measure the demineralization extent of bleached enamel with the Canary System™.

Protocol for a Case Control Study to Evaluate Oral Health as a Biomarker of Child Exposure to Adverse Psychosocial Experiences

Background: The early identification of children who have experienced adversity is critical for the timely delivery of interventions to improve coping and reduce negative consequences. Self-report is the usual practice for identifying children with exposure to adversity. However, physiological characteristics that signal the presence of disease or other exposures may provide a more objective identification strategy. This protocol describes a case–control study that assesses whether exposure to adversity is more common in children with tooth enamel anomalies compared to children without such anomalies. Methods: For 150 mother–child pairs from a pediatric dental clinic in Toronto, Canada, maternal interviews will assess the child’s adverse and resilience-building experiences. Per child, one (exfoliated or extracted) tooth will be assessed for suspected enamel anomalies. If anomalies are present, the child is a case, and if absent, the child is a control. Tooth assessment modalities will include usual practice for dental exams (visual assessment) and modalities with greater sensitivity to identify anomalies. Conclusion: If structural changes in children’s teeth are associated with exposure to adversity, routine dental exams could provide an opportunity to screen children for experiences of adversity. Affected children could be referred for follow-up.

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.

Validity of near-infrared light transillumination for the assessment of proximal caries in permanent teeth

PURPOSE

The aim of this study was to evaluate the performance of DIAGNOcam (DC) in diagnosing proximal caries and to compare its effectiveness with the International Caries Detection and Assessment System (ICDAS) and bitewing radiography (BWR).

METHODS

118 premolars extracted for orthodontic reasons were included and examined using three detection methods and validated by histological sections as the gold standard. The sensitivity, specificity and areas under the ROC curve (Az value) at the outer half enamel (D1), inner half enamel (D2) and dentine (D3) thresholds were compared between different methods.

RESULTS

At all categories, the specificity of DC was almost as high as ICDAS and BWR. DC showed a significantly higher sensitivity (0.68) than both visual (0.33) and radiographic examination (0.47) at the D1 threshold. DC presented the highest Az value (area under the ROC curve) at the D1 and D2 threshold (0.81, 0.86), while BWR showed the greatest Az values at D3 (0.94). Furthermore, DC had the highest association strength with the gold standard (Spearman's ρ = 0.80).

CONCLUSIONS

It can be concluded that DC could detect proximal caries effectively and showed comparable or even better performance than ICDAS and BWR.

Imaging modalities to inform the detection and diagnosis of early caries

BACKGROUND

The detection and diagnosis of caries at the earliest opportunity is fundamental to the preservation of tooth tissue and maintenance of oral health. Radiographs have traditionally been used to supplement the conventional visual-tactile clinical examination. Accurate, timely detection and diagnosis of early signs of disease could afford patients the opportunity of less invasive treatment with less destruction of tooth tissue, reduce the need for treatment with aerosol-generating procedures, and potentially result in a reduced cost of care to the patient and to healthcare services.

OBJECTIVES

To determine the diagnostic accuracy of different dental imaging methods to inform the detection and diagnosis of non-cavitated enamel only coronal dental caries.

SEARCH METHODS

Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 31 December 2018); Embase Ovid (1980 to 31 December 2018); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 31 December 2018); and the World Health Organization International Clinical Trials Registry Platform (to 31 December 2018). We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

We included diagnostic accuracy study designs that compared a dental imaging method with a reference standard (histology, excavation, enhanced visual examination), studies that evaluated the diagnostic accuracy of single index tests, and studies that directly compared two or more index tests. Studies reporting at both the patient or tooth surface level were included. In vitro and in vivo studies were eligible for inclusion. Studies that explicitly recruited participants with more advanced lesions that were obviously into dentine or frankly cavitated were excluded. We also excluded studies that artificially created carious lesions and those that used an index test during the excavation of dental caries to ascertain the optimum depth of excavation.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and in duplicate using a standardised data extraction form and quality assessment based on QUADAS-2 specific to the clinical context. Estimates of diagnostic accuracy were determined using the bivariate hierarchical method to produce summary points of sensitivity and specificity with 95% confidence regions. Comparative accuracy of different radiograph methods was conducted based on indirect and direct comparisons between methods. Potential sources of heterogeneity were pre-specified and explored visually and more formally through meta-regression.

MAIN RESULTS

We included 104 datasets from 77 studies reporting a total of 15,518 tooth sites or surfaces. The most frequently reported imaging methods were analogue radiographs (55 datasets from 51 studies) and digital radiographs (42 datasets from 40 studies) followed by cone beam computed tomography (CBCT) (7 datasets from 7 studies). Only 17 studies were of an in vivo study design, carried out in a clinical setting. No studies were considered to be at low risk of bias across all four domains but 16 studies were judged to have low concern for applicability across all domains. The patient selection domain had the largest number of studies judged to be at high risk of bias (43 studies); the index test, reference standard, and flow and timing domains were judged to be at high risk of bias in 30, 12, and 7 studies respectively. Studies were synthesised using a hierarchical bivariate method for meta-analysis. There was substantial variability in the results of the individual studies, with sensitivities that ranged from 0 to 0.96 and specificities from 0 to 1.00. For all imaging methods the estimated summary sensitivity and specificity point was 0.47 (95% confidence interval (CI) 0.40 to 0.53) and 0.88 (95% CI 0.84 to 0.92), respectively. In a cohort of 1000 tooth surfaces with a prevalence of enamel caries of 63%, this would result in 337 tooth surfaces being classified as disease free when enamel caries was truly present (false negatives), and 43 tooth surfaces being classified as diseased in the absence of enamel caries (false positives). Meta-regression indicated that measures of accuracy differed according to the imaging method (Chi2(4) = 32.44, P < 0.001), with the highest sensitivity observed for CBCT, and the highest specificity observed for analogue radiographs. None of the specified potential sources of heterogeneity were able to explain the variability in results. No studies included restored teeth in their sample or reported the inclusion of sealants. We rated the certainty of the evidence as low for sensitivity and specificity and downgraded two levels in total for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the in vitro studies, and the observed inconsistency of the results.

AUTHORS' CONCLUSIONS

The design and conduct of studies to determine the diagnostic accuracy of methods to detect and diagnose caries in situ are particularly challenging. Low-certainty evidence suggests that imaging for the detection or diagnosis of early caries may have poor sensitivity but acceptable specificity, resulting in a relatively high number of false-negative results with the potential for early disease to progress. If left untreated, the opportunity to provide professional or self-care practices to arrest or reverse early caries lesions will be missed. The specificity of lesion detection is however relatively high, and one could argue that initiation of non-invasive management (such as the use of topical fluoride), is probably of low risk. CBCT showed superior sensitivity to analogue or digital radiographs but has very limited applicability to the general dental practitioner. However, given the high-radiation dose, and potential for caries-like artefacts from existing restorations, its use cannot be justified in routine caries detection. Nonetheless, if early incidental carious lesions are detected in CBCT scans taken for other purposes, these should be reported. CBCT has the potential to be used as a reference standard in diagnostic studies of this type. Despite the robust methodology applied in this comprehensive review, the results should be interpreted with some caution due to shortcomings in the design and execution of many of the included studies. Future research should evaluate the comparative accuracy of different methods, be undertaken in a clinical setting, and focus on minimising bias arising from the use of imperfect reference standards in clinical studies.

Detection ability and direction effect of photothermal-radiometry and modulated-luminescence for non-cavitated approximal caries

OBJECTIVE

The objective was to evaluate the ability of photothermal-radiometry and modulated-luminescence (PTR/LUM) to detect non-cavitated approximal caries lesions, including the effect of scanning direction.

METHODS

Thirty human extracted premolars were selected based on micro-computed tomography [μ-CT: μ-CT = 0: sound (n = 12), μ-CT = 1: lesions into outer-half of enamel (n = 6), μ-CT = 2: lesions into inner-half of enamel (n = 6), and μ-CT = 3: lesions into outer one-third of dentine (n = 6)]. Teeth were mounted in a custom-made device to simulate approximal contact. Each tooth was scanned from three directions: buccal, lingual, and occlusal, then repeated 48 h later. Statistical analyses were performed by bootstrap analyses using average and maximum values across all directions. Sensitivity, specificity, area under ROC-curve (AUC), intraclass correlation coefficient (ICC) and correlation with μ-CT were calculated. Sensitivity was further evaluated based on lesion extension.

RESULTS

Using the manufacturer-suggested lesion cut-off, overall sensitivity ranged from 3%-61%, where the maximum value of all measurements (All-max) showed higher sensitivity (61 %) than other measurements except the buccal direction, which was also higher than the lingual and occlusal directions. As μ-CT score increased from μ-CT = 1-3, the sensitivity of All-max also increased from 50 % to 74 %. Specificity was 100 % regardless of direction, and AUC ranged from 0.65 to 0.88. All-max had the highest ICC (0.74). PTR/LUM values showed weak to moderate correlations with μ-CT.

CONCLUSION

Within the limitations of this in vitro study, PTR/LUM non-cavitated approximal caries lesion detection achieved best individual results from the buccal direction, while using the maximum value from all directions might improve performance.

CLINICAL SIGNIFICANCE

Non-cavitated approximal caries detection is a challenging procedure. PTR/LUM is a nondestructive, no ionized-radiation caries detection method that can scan from buccal, lingual, and occlusal directions of an approximal surface. PTR/LUM seems suitable to detect deeper non-cavitated approximal caries. The maximum PTR/LUM value from three directions may be optimal.

Multi-Centre Clinical Evaluation of Photothermal Radiometry and Luminescence Correlated with International Benchmarks for Caries Detection

INTRODUCTION

A clinical study was initiated to investigate a caries detection device (The Canary System (CS)), based on photothermal radiometry and modulated luminescence (PTR-LUM). The primary objective of this study was to determine if PTR-LUM values (in the form of Canary Numbers; CN) correlate with International Caries Diagnostic and Assessment System (ICDAS II) scores and clinical situations. The secondary objectives of this study were to monitor the safety of PTR-LUM, and collect data to determine how CN values could be used to differentiate healthy from decayed tooth surfaces on a normalized scale.

METHODS

The trial was a four site, non-blinded study. Data was collected from 92 patients, resulting in 842 scanned tooth surfaces over multiple appointments. Surfaces were assessed according to ICDAS II, and further stratified into five clinical situation categories: 1) healthy surface, 2) non-cavitated white and/or brown spots; 3) caries lesions; 4) cavitation and 5) teeth undergoing remineralization therapy.CN data was analyzed separately for smooth and occlusal surfaces. Using a semi-logarithmic graph to plot raw CN (rCN) and normalized (CN) values, rCN data was normalized into a scale of 0-100.

RESULTS

Linear correlations (R2) between CN and ICDAS II groupings for smooth and occlusal surfaces were calculated as 0.9759 and 0.9267, respectively. The mean CN values derived from smooth (20.2±0.6) and occlusal (19±1.0) surfaces identified as healthy had significantly lower CN values (P<0.05) compared with the values from the other clinical situation categories. No adverse events were reported.

CONCLUSION

The present study demonstrated the safety of PTR-LUM for clinical application and its ability to distinguish sound from carious tooth surfaces. A clear shift from the baseline in both PTR and LUM in carious enamel was observed depending on the type and nature of the lesion, and correlated to ICDAS II classification codes, which enabled the preliminary development of a Canary Scale.

Effect of non-fluoride agents on the prevention of dental caries in primary dentition: A systematic review

Objective

To assess the effect of non-fluoride agents on the prevention of dental caries in primary dentition.

Materials and methods

Medline, Web of Science, Embase, Cochrane Library, CBM and CNKI databases were searched to identify all the relevant articles published prior to 16 December 2016. Grey literature was also searched. Randomized controlled human clinical trials in which non-fluoride agents were delivered by any method were considered.

Results

Of the 1,236 studies screened, 39 full articles were scrutinized and 14 selected for inclusion in the final sample. Five chemical agents, namely arginine, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), chlorhexidine, triclosan and xylitol were investigated in these included studies. The cariostatic effects of non-fluoride agents in vivo were evaluated in comparison with fluoride or placebos in randomized controlled trials. There is evidence that the use of certain doses of xylitol may be effective in arresting dental caries in primary dentition. However, quantitative synthesis could not be carried out because of the clinical and methodological heterogeneity of the included studies.

Conclusions

A study at low risk of bias indicated that daily use of xylitol wipes is a useful adjunct for caries control in young children, however, this conclusion should be interpreted with caution as this study had a very limited sample size. Chlorhexidine and CPP-ACP may be more effective than a placebo in managing caries in primary dentition, but their effectiveness is borderline when compared with fluoride. Arginine-containing mint confection and 0.3% triclosan varnish were found to reduce caries development in primary teeth but the evidence was at high risk of bias. High quality randomized controlled trials are needed in order to make a conclusive recommendation.

The Use of Optical Coherence Tomography in Dental Diagnostics: A State-of-the-Art Review

Optical coherence tomography provides sections of tissues in a noncontact and noninvasive manner. The device measures the time delay and intensity of the light scattered or reflected from biological tissues, which results in tomographic imaging of their internal structure. This is achieved by scanning tissues at a resolution ranging from 1 to 15 μm. OCT enables real-time in situ imaging of tissues without the need for biopsy, histological procedures, or the use of X-rays, so it can be used in many fields of medicine. Its properties are not only particularly used in ophthalmology, in the diagnosis of all layers of the retina, but also increasingly in cardiology, gastroenterology, pulmonology, oncology, and dermatology. The basic properties of OCT, that is, noninvasiveness and low wattage of the used light, have also been appreciated in analytical technology by conservators, who use it to identify the quality and age of paintings, ceramics, or glass. Recently, the OCT technique of visualization is being tested in different fields of dentistry, which is depicted in the article.

Alternative methods to visual and radiographic examinations for approximal caries detection

A shift in caries prevalence from occlusal surfaces to approximal surfaces has been demonstrated by epidemiological studies. Two recent meta-analyses evaluated the performance of visual examination and radiography for carious lesion detection, and reported low sensitivity but high specificity for early approximal caries detection. This suggests that the conventional methods have a higher risk of failing to detect approximal lesions. Consequently, in caries susceptible populations, there is a risk of progression of non-cavitated lesions to irreversible tooth destruction before the lesions are detected. This paper aims to review the performance of unconventional and novel methods for approximal caries detection. In vitro and in vivo studies identified through a MEDLINE search using keywords such as caries detection, approximal caries detection, light fluorescence and dental caries, and transillumination and dental caries were reviewed. The unconventional methods known to be used for approximal caries detection and included in this review are: cone beam computed tomography, fiber-optic trans-illumination, digital imaging fiber optic trans-illumination, near-infrared digital imaging transillumination, optical coherence tomography, laser fluorescence, ultrasound, and LED reflection and refraction.