Daniela Fátima Teixeira Silva

To investigate the surface modification (changes in roughness, morphology, and chemical composition) of human enamel subjected to multiple Nd:YAG laser irradiations over a photoabsorber, with and without the subsequent application of acidulated phosphate fluoride (APF), in a caries control protocol. 150 enamel blocks (4 × 4 mm) from human third molars were randomly distributed into 10 groups based on surface microhardness: control groups (CN, CF) and irradiated groups subjected to 1, 2, 3, or 4 successive scans. A pulsed Nd:YAG laser (1064 nm, 65 mJ/pulse, 10 Hz, 51.7 J/cm²) irradiated the surfaces using a motorized stage with calculated speed for partial pulse overlap. An aqueous coal powder suspension (equal parts of ultrapure water and 99% ethanol) was applied before each scan. APF 1.23% was applied post-irradiation for the fluoridated groups. The surfaces were analyzed by optical profilometry (Sa), Scanning Electron Microscopy (SEM), and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR). Qualitative analysis of profilometry and SEM images revealed that one or two laser scans resulted in unaltered areas and spaces of non-melted enamel between pulses. Groups irradiated three or four times achieved more uniform areas of surface melting, also exhibiting significantly higher surface roughness. ATR-FTIR analysis, guided by multivariate models and semi-quantitative analysis, showed indications that laser irradiation promoted thermal decarbonation of the enamel and caused the narrowing of phosphate bands. One or two Nd:YAG laser scans were insufficient to modify the entire enamel surface. Successive irradiations with reapplication of the photoabsorber must be performed to ensure that the whole targeted area is modified, despite the localized increase in surface roughness.

Antibiotics (ATBs) remain a cornerstone in the treatment of bacterial infections, yet clinical practice increasingly incorporates photonic therapies such as photobiomodulation (PBM) and photodynamic therapy (PDT). These modalities, widely used in infectious and inflammatory conditions, are frequently administered concomitantly with ATBs. However, the potential photochemical interactions between β-lactam ATBs and light-based therapies remain poorly understood, raising questions about efficacy and safety in combined treatment settings. In this study, we characterized the optical and photochemical properties of representative β-lactam ATBs, including penicillins (amoxicillin, oxacillin), cephalosporins (cephalothin, cefazolin, ceftazidime, ceftriaxone, cefuroxime), and a carbapenem (meropenem). Using diffuse transmittance and reflectance spectroscopy, we calculated absorption and scattering coefficients via the Kubelka–Munk function. Reactive oxygen species (ROS) generation was assessed under direct blue light (460 nm) illumination and red light exposure in the presence of methylene blue (MB), a clinically employed photosensitizer. Cephalosporins demonstrated significant ROS generation under blue light, whereas penicillins and meropenem did not. In PDT-like conditions, meropenem enhanced MB-mediated ROS production and promoted MB photobleaching, suggesting potentiation of PDT effects. In contrast, penicillins suppressed MB-driven ROS generation, potentially limiting PDT efficacy. Cephalosporins showed heterogeneous effects, either enhancing, reducing, or leaving MB-induced ROS unchanged. These findings indicate that β-lactam ATBs exert distinct photobiological behaviors with potential clinical consequences. Cephalosporins may act as intrinsic photosensitizers, meropenem may potentiate PDT, and penicillins may attenuate phototherapy efficacy. Recognizing such interactions is critical to optimizing combined ATB–phototherapy regimens and avoiding unintended antagonism or toxicity in clinical practice.

Dentin hypersensitivity (DH) is characterized by intense, short-lasting pain, triggered by dentin exposure to different stimuli. It is often associated with hypomineralized teeth due to increased enamel porosity and exposed dentinal tubules. The high-power Er: YAG laser has emerged as a promising therapeutic strategy for the treatment of this condition. The aim of this in vitro study was to test different protocols for managing dentin hypersensitivity in hypomineralized teeth using a high-power Er: YAG laser. Six protocols were evaluated, varying in power, frequency, application mode, and the use of cooling. Qualitative analysis of morphological changes were evaluated by scanning electron microscopy (SEM). Further, the most promising protocol – 20 mJ, 10 Hz, 0.20 watts, applied in focused mode, without cooling – was selected for assessing intrapulpal temperature variation using thermocouples connected to a monitoring system. The SEM images showed that this protocol promoted homogeneous surface melting of dentin, effectively sealing the dentinal tubules without inducing a thermal increase greater than 2 °C. These findings support the feasibility of using the Er: YAG laser with conservative parameters and no cooling as a safe and effective alternative for the management of DH in hypomineralized teeth. However, clinical trials are recommended to validate its applicability in pediatric dentistry.

This study investigates the innovative use of gold nanorods (AuNRs) as optical clearing agents to enhance detailed visualization of the cementoenamel junction (CEJ) in optical coherence tomography (OCT), a non-invasive imaging modality. Eighty extracted teeth were carefully examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to classify CEJ types. Imaging was performed under four distinct contrast conditions: air (G1), glycerol (G2), AuNRs (G3), and AuNRs combined with glycerol (G4). Statistical analysis (ANOVA and Tukey’s test, p < 0.05) showed that AuNRs, especially in G4, significantly enhanced CEJ visualization by reducing scattering and improving image contrast. Specifically, for the enamel region, the AuNRs-containing groups (G3 and G4) showed the lowest attenuation coefficients (0.0011100 and 0.0010435, respectively), compared to groups 2 and 1. The same was observed in the CEJ region: the AuNRs-containing groups (G3 and G4) showed the lowest attenuation coefficients (0.0010830 and 0.0009060, respectively). Attenuation analysis indicated greater absorption in the enamel and CEJ regions with AuNRs and glycerol, while cementum remained unaffected. The preservation of cementum suggests that the combination of AuNRs and glycerol enhanced OCT imaging without compromising tissue integrity. These results highlight the potential of AuNRs to further enhance OCT-based CEJ imaging for detecting clinically significant “gaps,” thereby advancing its role as a reliable diagnostic tool in dentistry.

This study evaluated class balancing strategies for classifying oral squamous cell carcinoma (OSCC) in FTIR hyperspectral images using the XGBoost model. Although the dataset was balanced at the image level, spectral quality filtering introduced pixel-level class imbalance. Resampling methods—SMOTE, Tomek Links, and their combination—were tested, as well as AllKNN for redundancy reduction. All approaches outperformed the unbalanced baseline, but the best overall performance metrics were achieved with the combined use of AllKNN and Tomek Links.

Antibiotic quality has always been a concern in the pharmaceutical industry and the World Health Organization (WHO), especially in the growing and emerging antimicrobial resistance crisis. FTIR spectroscopy can contribute to the monitoring of antimicrobials, especially when coupled with chemometric techniques. The present work aims to investigate spectral differences of Ampicillin samples through FTIR qualitatively and quantitatively, highlighting the spectral differences associated with different degradation conditions (acidic and thermal).

This study evaluates the classification of oral squamous cell carcinoma (OSCC) using micro-FTIR hyperspectral imaging and two tree-based models: Random Forest and XGBoost. After preprocessing and PCA, class imbalance was addressed with AllKNN and Tomek Links. Both models achieved high accuracy, and key spectral bands-Amide I, II, and III-were consistently highlighted, supporting their relevance in oral cancer detection.

Introduction: Amoxicillin and Ampicillin are among the most widely used antibiotics for treating bacterial infections. While traditional drug monitoring methods often face challenges relative to accuracy and analysis speed, optical-based techniques offer a promising alternative. Fourier Transform Infrared Spectroscopy (FTIR), a well-established tool, is particularly suited for this purpose. As their molecular structures and characteristic infrared absorption features are very similar, they could be difficult to differentiate using FTIR spectroscopy. Hence, chemometric analysis is important to overcome this challenge. This study introduces a novel approach to the standard methods of antibiotic detection and monitoring, leveraging the capabilities of vibrational spectroscopy and helping in antimicrobial stewardship. Attenuated Total Reflection (ATR)–FTIR is carried out with chemometric tools to investigate Amoxicillin and Ampicillin over different degradation processes. Principal Component Analysis (PCA) was used in the fingerprint region to detect differences between the studied antibiotics. Additionally, absorbance intensity in the fingerprint region was monitored to assess the degradation of each antibiotic over time. To achieve this, the area under the curve was calculated and subjected to inferential statistical tests for both intragroup (the degradation of the same antibiotic) and intergroup (degradation within the same time interval, comparing the two antibiotics) comparisons. All analyses were performed in OriginLab and using Python in the Google Colab and Orange environments. For the calculations of the limit of detection (LoD), the method based on the calibration curve was used. Through the experiments, it was possible to identify the fingerprints of each antibiotic and statistically separate them, despite both belonging to the same class of antibiotics, where the spectral peaks appear in the same region. For degradation, all tests were conducted with a significance level of α = 5%. In this investigation, our results show several quantification characteristics with a detection limit of 96.76 mM for Ampicillin and 66.01 mM for Amoxicillin using the peak intensity. This research demonstrates that FTIR spectroscopy is effective for antibiotic detection and has the potential to be further developed into a monitoring protocol.

This brief report aimed to investigate the optical absorbance spectra of normal, dysplastic, and malignant epithelial cell lines under normal and nutritional stress conditions. HaCAT (keratinocyte), DOK (oral dysplastic), and oral squamous cell carcinoma (OSCC) cell lines (CA1, Luc4, SCC9) were evaluated regarding their optical absorbance after culture with 0–10% fetal bovine serum. Absorbance measurements indicated that HaCAT under serum starvation exhibited higher absorbance at blue (430 nm) and near-infrared (906 nm) wavelengths. DOK showed absorption at 440 nm and 945 nm. OSCC cells showed absorption peaks at blue (400–428 nm) and near-infrared. These findings highlight the importance of tailoring PBM parameters to individual needs to achieve optimal absorption and effectiveness. Moreover, the higher absorption peaks in the blue region support further studies to elucidate the potential use of blue light in oral dysplastic lesions and OSCC.