Detection and analysis of enamel cracks by ICG-NIR fluorescence dental imaging

Innovative Approaches in Dental Care: Electrical Impedance Analysis (EIA) for Early Caries Detection

(1) Background: Microcracks and structural fragility in teeth, often undetected by traditional methods until severe complications like fractures or pulp exposure occur, are evaluated in this study using electrical impedance analysis (EIA) as a non-invasive tool for early detection and assessment. (2) Methods: A total of 57 patients were recruited, including individuals with bruxism (n = 20), dental restorations (n = 18), and no significant dental history (control group, n = 19). Electrical impedance measurements were performed on all teeth using a portable device, with data collected from occlusal and proximal surfaces. Patients with abnormal values underwent additional imaging (standard radiographs) to confirm the presence of microcracks. Statistical analyses included ANOVA to compare impedance values between groups and logistic regression to assess the predictors of structural fragility. (3) Results: Teeth with microcracks confirmed by standard radiographs exhibited significantly lower impedance values (mean 50 kΩ) compared to healthy teeth (mean 120 kΩ, p < 0.01). Patients with bruxism showed the highest proportion of teeth with abnormal impedance (45%). Logistic regression identified bruxism as a significant predictor of reduced impedance values (p < 0.05). (4) Conclusions: Electrical impedance analysis demonstrates promise as a non-invasive method for detecting microcracks and assessing structural fragility in teeth. Its application in routine dental check-ups could enable early interventions, particularly for high-risk patients with bruxism or restorations.

Human Tooth Crack Image Analysis with Multiple Deep Learning Approaches

Tooth cracks, one of the most common dental diseases, can result in the tooth falling apart without prompt treatment; dentists also have difficulty locating cracks, even with X-ray imaging. Indocyanine green (ICG) assisted near-infrared fluorescence (NIRF) dental imaging technique can solve this problem due to the deep penetration of NIR light and the excellent fluorescence characteristics of ICG. This study extracted 593 human cracked tooth images and 601 non-cracked tooth images from NIR imaging videos. Multiple imaging analysis methods such as classification, object detection, and super-resolution were applied to the dataset for cracked image analysis. Our results showed that machine learning methods could help analyze tooth crack efficiently: the tooth images with cracks and without cracks could be well classified with the pre-trained residual network and squeezenet1_1 models, with a classification accuracy of 88.2% and 94.25%, respectively; the single shot multi-box detector (SSD) was able to recognize cracks, even if the input image was at a different size from the original cracked image; the super-resolution (SR) model, SR-generative adversarial network demonstrated enhanced resolution of crack images using high-resolution concrete crack images as the training dataset. Overall, deep learning model-assisted human crack analysis improves crack identification; the combination of our NIR dental imaging system and deep learning models has the potential to assist dentists in crack diagnosis.

Enamel microcrack inspection using near-infrared light transillumination with fluorescence staining

Enamel microcracks are often apparent in the teeth of elderly individuals. However, accurate clinical diagnosis of enamel microcracks is very difficult. The purpose of this study was to examine the utility of inspections for enamel microcracks using a near-infrared light transillumination device with fluorescence staining. Human upper incisors with typical enamel microcracks were selected. Grayscale pictures of each tooth specimen were then taken by digital camera under visible light as control. Every tooth specimen was stained using indocyanine green solutions, then examined, and photographed under visible light. All digital images were compared with the background enamel surface and measured using image analysis software. Inspection using near-infrared light transillumination with indocyanine green solution was effective for detecting the presence of enamel microcracks. This method offers a non-invasive method of chair-side diagnosis and appears effective for detecting the presence of enamel microcracks.

Near-Infrared Mechanoluminescence from Cr3+-Doped Spinel Nanoparticles for Potential Oral Diseases Detection

Mechanoluminescence (ML) phosphors have found various promising utilizations such as in non-destructive stress sensing, anti-counterfeiting, and bio stress imaging. However, the reported NIR MLs have predominantly been limited to bulky particle size and weak ML intensity, hindering the further practical applications. For this regard, a nano-sized ZnGa2O4: Cr3+ NIR ML phosphor is synthesized by hydrothermal method. By improving the synthesis method and regulating the chemical composition, the NIR ML (600-1000 nm) intensity of such nano-materials has been further enhanced about four times. The reasons for the ML performance difference between micro-/nano- sized phosphors also have been preliminarily analyzed. Additionally, this work probes into the ML mechanism deeply in traps' aspect from band structure and defect formation energy, which can supply significant references for a new approach to develop efficient NIR ML nanoparticles. Finally, due to excellent tissue penetration capability, nano-sized ZnGa2O4:Cr3+ NIR ML phosphor shows great potential applications in biomedical fields such as for the detection of clinical oral diseases.

Repurposing indocyanine green: exploring the potential of an old drug in modern medicine

The repurposing of existing drugs, referred to as theranostics, has made profound impacts on precision medicine. Indocyanine green (ICG), a well-established and clinical dye, has continued to be a star agent, described as a multifunctional molecule with concurrent photo- or sono-sensitiveness capabilities and co-delivery accessibility, showing remarkable potential in the area of unimodal or multimodal imaging-guided therapy of various diseases, leading to the extensive consideration of immediate clinical translations. In this review, we strive to bring the understanding of repurposing performance assessment for ICG into practice by clarifying the relationships between its features and applicability. Specifically, we address the obstacles encountered in the process of developing an ICG repurposing strategy, as well as the noteworthy advancements made in the field of ICG repurposing. We also go into detail about the structure-function correlations of drugs containing ICG and how different structural groups significantly affect the physicochemical properties.

Teeth Microcracks Research: Towards Multi-Modal Imaging

This perspective is an overview of the recent advances in teeth microcrack (MC) research, where there is a clear tendency towards a shift from two-dimensional (2D) to three-dimensional (3D) examination techniques, enhanced with artificial intelligence models for data processing and image acquisition. X-ray micro-computed tomography combined with machine learning allows 3D characterization of all spatially resolved cracks, despite the locations within the tooth in which they begin and extend, and the arrangement of MCs and their structural properties. With photoluminescence and micro-/nano-Raman spectroscopy, optical properties and chemical and elemental composition of the material can be evaluated, thus helping to assess the structural integrity of the tooth at the MC site. Approaching tooth samples having cracks from different perspectives and using complementary laboratory techniques, there is a natural progression from 3D to multi-modal imaging, where the volumetric (passive: dimensions) information of the tooth sample can be supplemented by dynamic (active: composition, interaction) image data. Revelation of tooth cracks clearly shows the need to re-assess the role of these MCs and their effect on the structural integrity and longevity of the tooth. This provides insight into the nature of cracks in natural hard materials and contributes to a better understanding of how bio-inspired structures could be designed to foresee crack propagation in biosolids.

The Potential Role of Ionic Liquid as a Multifunctional Dental Biomaterial

In craniofacial research and routine dental clinical procedures, multifunctional materials with antimicrobial properties are in constant demand. Ionic liquids (ILs) are one such multifunctional intelligent material. Over the last three decades, ILs have been explored for different biomedical applications due to their unique physical and chemical properties, high task specificity, and sustainability. Their stable physical and chemical characteristics and extremely low vapor pressure make them suitable for various applications. Their unique properties, such as density, viscosity, and hydrophilicity/hydrophobicity, may provide higher performance as a potential dental material. ILs have functionalities for optimizing dental implants, infiltrate materials, oral hygiene maintenance products, and restorative materials. They also serve as sensors for dental chairside usage to detect oral cancer, periodontal lesions, breath-based sobriety, and dental hard tissue defects. With further optimization, ILs might also make vital contributions to craniofacial regeneration, oral hygiene maintenance, oral disease prevention, and antimicrobial materials. This review explores the different advantages and properties of ILs as possible dental material.

Original and liposome-modified indocyanine green-assisted fluorescence study with animal models

Medical diagnosis heavily relies on the use of bio-imaging techniques. One such technique is the use of ICG-based biological sensors for fluorescence imaging. In this study, we aimed to improve the fluorescence signals of ICG-based biological sensors by incorporating liposome-modified ICG. The results from dynamic light scattering and transmission electron microscopy showed that MLM-ICG was successfully fabricated with a liposome diameter of 100-300 nm. Fluorescence spectroscopy showed that MLM-ICG had the best properties among the three samples (Blank ICG, LM-ICG, and MLM-ICG), as samples immersed in MLM-ICG solution achieved the highest fluorescence intensity. The NIR camera imaging also showed a similar result. For the rat model, the best period for fluorescence tests was between 10 min and 4 h, where most organs reached their maximum fluorescence intensity except for the liver, which continued to rise. After 24 h, ICG was excreted from the rat's body. The study also analyzed the spectra properties of different rat organs, including peak intensity, peak wavelength, and FWHM. In conclusion, the use of liposome-modified ICG provides a safe and optimized optical agent, which is more stable and efficient than non-modified ICG. Incorporating liposome-modified ICG in fluorescence spectroscopy could be an effective way to develop novel biosensors for disease diagnosis.

The influence of age and orthodontic debonding on the prevalence and severity of enamel craze lines

BACKGROUND

Craze lines may cause esthetic concerns, especially when noted on the incisors. Various light sources with additional recording apparatus have been proposed to visualize craze lines, but a standardized clinical protocol is yet to be determined. This study aimed to validate the application of near-infrared imaging (NIRI) from intraoral scans to evaluate craze lines and to determine the influence of age and orthodontic debonding on their prevalence and severity.

METHODS

The NIRI of maxillary central incisors from a full-mouth intraoral scan and photographs from an orthodontic clinic (N = 284) were collected. The prevalence of craze lines and influence of age and orthodontic debonding history on severity were evaluated.

RESULTS

Craze lines were detected reliably as white lines distinguishable from dark enamel using the NIRI from intraoral scans. The craze line prevalence was 50.7%, which was significantly higher in patients 20 years or older than in patients younger than 20 years (P < .001), with more frequent severe craze lines for those 40 years or older than in patients younger than 30 years (P < .05). Prevalence or severity was similar between patients with and without an orthodontic debonding history regardless of the type of appliance.

CONCLUSION

The prevalence of craze lines in the maxillary central incisor was 50.7%, with a higher prevalence in adults than in adolescents. Orthodontic debonding did not affect the severity of craze lines.

PRACTICAL IMPLICATIONS

Craze lines were reliably detected and documented by means of applying NIRI from intraoral scans. Intraoral scanning can provide new clinical information on enamel surface characteristics.

Three Visual-Diagnostic Methods for the Detection of Enamel Cracks: An In Vitro Study

Tooth fractures are a common cause of tooth loss, frequently starting as enamel cracks. However, methods for the detection of enamel cracks are poorly investigated. The aim of the study was the validation of three clinical methods for the detection of enamel cracks: dental operating microscope (DOM), near-infrared transillumination (NIR), and fiber-optic transillumination (FOTI), with hard-tissue slices serving as controls. A total of 89 extracted teeth, set up as diagnostic models, were investigated, and the maximum crack depth was scored by two examiners. The actual crack depth was determined microscopically (25×) using horizontal sections. The accuracy of each method was analyzed using receiver operating characteristic (ROC) curves. Across all tooth surfaces, the area under the curve (AUC) amounted to 0.57 (DOM), 0.70 (FOTI), and 0.67 (NIR). For crack detection on vestibular/oral surfaces, the AUC was 0.61 (DOM), 0.78 (FOTI), and 0.74 (NIR); for proximal surfaces, it was 0.59 (DOM), 0.65 (FOTI), and 0.67 (NIR). However, the actual crack depth was underestimated with each method (p < 0.001). Under in vitro conditions, FOTI and NIR are suitable for detection of enamel cracks, especially on vestibular and oral tooth surfaces. However, an exact estimation of crack depth is not possible. Therefore, FOTI and NIR seem to be helpful for the clinical detection of enamel cracks.

Revelation of microcracks as tooth structural element by X-ray tomography and machine learning

Although teeth microcracks (MCs) have long been considered more of an aesthetic problem, their exact role in the structure of a tooth and impact on its functionality is still unknown. The aim of this study was to reveal the possibilities of an X-ray micro-computed tomography ([Formula: see text]CT) in combination with convolutional neural network (CNN) assisted voxel classification and volume segmentation for three-dimensional (3D) qualitative analysis of tooth microstructure and verify this approach with four extracted human premolars. Samples were scanned using a [Formula: see text]CT instrument (Xradia 520 Versa; ZEISS) and segmented with CNN to identify enamel, dentin, and cracks. A new CNN image segmentation model was trained based on "Multiclass semantic segmentation using DeepLabV3+" example and was implemented with "TensorFlow". The technique which was used allowed 3D characterization of all MCs of a tooth, regardless of the volume of the tooth in which they begin and extend, and the evaluation of the arrangement of cracks and their structural features. The proposed method revealed an intricate star-shaped network of MCs covering most of the inner tooth, and the main crack planes in all samples were arranged radially in two almost perpendicular directions, suggesting that the cracks could be considered as a planar structure.

Diagnosis of cracked tooth: Clinical status and research progress

Cracked tooth is a common dental hard tissue disease.The involvement of cracks directly affects the selection of treatment and restoration of the affected teeth.It is helpful to choose more appropriate treatment options and evaluate the prognosis of the affected tooth accurately to determine the actual involvement of the crack.However, it is often difficult to accurately and quantitatively assess the scope of cracks at present.So it is necessary to find a real method of early quantitative and non-destructive crack detection.This article reviews the current clinical detection methods and research progress of cracked tooth in order to provide a reference for finding a clinical detection method for cracked tooth.

Recent Advances in the Diagnosis of Enamel Cracks: A Narrative Review

Cracked teeth can pose a diagnostic dilemma for a clinician as they can mimic several other conditions. The constant physiological stress along with any pathological strain like trauma or iatrogenic causes can lead to the development of microcracks in the teeth. Constant exposure to immense stress can cause the progression of these often-undiagnosed tooth cracks to cause tooth fractures. This review aims to outline the etiology of tooth cracks, their classification, and recent advances in the diagnosis of enamel cracks. Diagnosing a cracked tooth can be an arduous task as symptoms differ according to the location and extension of the incomplete fracture. Early detection is critical because restorative treatment can prevent fracture propagation, microleakage, pulpal or periodontal tissue involvement, and catastrophic cusp failure. Older methods of crack detection are not sensitive or specific. They include clinical examination, visual inspection, exploratory excavation, and percussion test. The dye test used blue or gentian violet stains to highlight fracture lines. Modern methods include transillumination, optical coherence tomography Swept-Source Optical Coherence Tomography (SSOCT), near-infrared imaging, ultrasonic system, infrared thermography, and near-infrared laser. These methods appear to be more efficacious than traditional clinical dental imaging techniques in detecting longitudinal tooth cracks. Clinically distinguishing between the various types of cracks can be difficult with patient-reported signs and symptoms varying according to the location and extension of the incomplete fracture. Cracks are more common in restored teeth. Technological advances such as transillumination allow for early detection and enhanced prognosis.

Mouthwash as a non-invasive method of indocyanine green delivery for near-infrared fluorescence dental imaging

SIGNIFICANCE

X-ray imaging serves as the mainstream imaging in dentistry, but it involves risk of ionizing radiation.

AIM

This study presents the feasibility of indocyanine green-assisted near-infrared fluorescence (ICG-NIRF) dental imaging with 785-nm NIR laser in the first (ICG-NIRF-I: 700 to 1000 nm) and second (ICG-NIRF-II: 1000 to 1700 nm) NIR wavelengths.

APPROACH

Sprague Dawley rats with different postnatal days were used as animal models. ICG, as a fluorescence agent, was delivered to dental structures by subcutaneous injection (SC) and oral administration (OA).

RESULTS

For SC method, erupted and unerupted molars could be observed from ICG-NIRF images at a short imaging time (<1  min). ICG-NIRF-II could achieve a better image contrast in unerupted molars at 24 h after ICG injection. The OA could serve as a non-invasive method for ICG delivery; it could also cause the glow-in-dark effect in unerupted molars. For erupted molars, OA can be considered as mouthwash and exhibits outstanding performance for delivery of ICG dye; erupted molar structures could be observed at a short imaging time (<1  min) and low ICG dose (0.05  mg  /  kg).

CONCLUSIONS

Overall, ICG-NIRF with mouthwash could perform in-vivo dental imaging in two NIR wavelengths at a short time and low ICG dose.

Review of Cracked Tooth Syndrome: Etiology, Diagnosis, Management, and Prevention

Cracked tooth syndrome refers to a series of symptoms caused by cracked teeth. This article reviews the current literature on cracked tooth syndrome from four aspects, etiology, diagnosis, management, and prevention, to provide readers integrated information about this. The article begins with an introduction to the odontiatrogenic factors and then covers the noniatrogenic factors that induce cracked tooth syndrome. While the former discusses inappropriate root canal therapy and improper restorative procedures, the latter covers the topics such as the developmental and functional status of cracked tooth syndrome. This is then followed by the description of common clinical diagnosis methods, the prospects of new technologies, and summaries of current clinical management methods, including immediate management and direct and indirect restoration. In the final section, preventive methods and their importance are proposed, with the aim of educating the common population.

A Comprehensive Review on the Optical Micro-Electromechanical Sensors for the Biomedical Application

This study presented an overview of current developments in optical micro-electromechanical systems in biomedical applications. Optical micro-electromechanical system (MEMS) is a particular class of MEMS technology. It combines micro-optics, mechanical elements, and electronics, called the micro-opto electromechanical system (MOEMS). Optical MEMS comprises sensing and influencing optical signals on micron-level by incorporating mechanical, electrical, and optical systems. Optical MEMS devices are widely used in inertial navigation, accelerometers, gyroscope application, and many industrial and biomedical applications. Due to its miniaturised size, insensitivity to electromagnetic interference, affordability, and lightweight characteristic, it can be easily integrated into the human body with a suitable design. This study presented a comprehensive review of 140 research articles published on photonic MEMS in biomedical applications that used the qualitative method to find the recent advancement, challenges, and issues. The paper also identified the critical success factors applied to design the optimum photonic MEMS devices in biomedical applications. With the systematic literature review approach, the results showed that the key design factors could significantly impact design, application, and future scope of work. The literature of this paper suggested that due to the flexibility, accuracy, design factors efficiency of the Fibre Bragg Grating (FBG) sensors, the demand has been increasing for various photonic devices. Except for FBG sensing devices, other sensing systems such as optical ring resonator, Mach-Zehnder interferometer (MZI), and photonic crystals are used, which still show experimental stages in the application of biosensing. Due to the requirement of sophisticated fabrication facilities and integrated systems, it is a tough choice to consider the other photonic system. Miniaturisation of complete FBG device for biomedical applications is the future scope of work. Even though there is a lot of experimental work considered with an FBG sensing system, commercialisation of the final FBG device for a specific application has not been seen noticeable progress in the past.