Evaluation of mineral content in healthy permanent human enamel by Raman spectroscopy

An understanding of tooth enamel mineral content using a clinically viable method is essential since variations in mineralization may serve as an early precursor of a dental health issues, and may predict progression and architecture of decay in addition to assessing the success and effectiveness of the remineralization strategies. Twenty two human incisor teeth were obtained in compliance with the NIH guidelines and site specifically imaged with Raman microscope. The front portion of the teeth was divided into apical, medium and cervical regions and subsequently imaged with Raman microscope in these three locations. Measured mineralization levels have varied substantially depending on the regions. It was also observed that, the cervical enamel is the least mineralization as a populational average. Enamel mineralization is affected by a many factors such as are poor oral hygiene, alcohol consumption and high intake of dietary carbohydrates, however the net effect manifests as overall mineral content of the enamel. Thus an early identification of the individual with overall low mineral content of the enamel may be a valuable screening tool in determining a group with much higher than average caries risk, allowing intervention before development of caries. Clinically applicable non-invasive techniques that can quantify mineral content, such as Raman analysis, would help answer whether or not mineralization is associated with caries risk

A portable fiber-optic raman spectrometer concept for evaluation of mineral content within enamel tissue

Measurement of tooth enamel mineralization using a clinically viable method is essential since variation of mineralization may be used to monitor caries risk or in assessing the effectiveness of remineralization therapy. Fiber optic Raman systems are becoming more affordable and popular in context of biomedical applications. However, the applicability of fiber optic Raman systems for measurement of mineral content within enamel tissue has not been elucidated significantly in the prior literature. Human teeth with varying degrees of enamel mineralization were selected. In addition alligator, boar and buffalo teeth which have increasing amount of mineral content, respectively, were also included as another set of samples. Reference Raman measurements of mineralization were performed using a high-fidelity confocal Raman microscope. Analysis of human teeth by research grade Raman system indicated a 2-fold difference in the Raman intensities of v1 symmetric-stretch bands of mineral-related phosphate bonds and 7-fold increase in mineral related Raman intensities of animal teeth. However, fiber optic system failed to resolve the differences in the mineralization of human teeth. These results indicate that the sampling volume of fiber optic systems extends to the underlying dentin and that confocal aperture modification is essential to limit the sampling volume to within the enamel. Further research efforts will focus on putting together portable Raman systems integrated with confocal fiber probe

Mechanical properties and DIC analyses of CAD/CAM materials

This study compared two well-known computer-aided-design/computer-aided-manufactured (CAD/CAM) blocks (Paradigm MZ100 [3M ESPE] and Vitablocs Mark II [Vita] in terms of fracture toughness (Kic), index of brittleness (BI) and stress/strain distributions. Three-point bending test was used to calculate the fracture toughness, and the relationship between the Kic and the Vickers hardness was used to calculate the index of brittleness. Additionally, digital image correlation (DIC) was used to analyze the stress/strain distribution on both materials. The values for fracture toughness obtained under three-point bending were 1.87Pa√m (±0.69) for Paradigm MZ100 and 1.18Pa√m (±0.17) for Vitablocs Mark II. For the index of brittleness, the values for Paradigm and Vitablocs were 73.13μm-1/2 (±30.72) and 550.22μm-1/2 (±82.46). One-way ANOVA was performed to find differences (α=0.05) and detected deviation between the stress/strain distributions on both materials. Both CAD/CAM materials tested presented similar fracture toughness, but, different strain/stress distributions. Both materials may perform similarly when used in CAD/CAM restorations

Outcomes of aggressive treatment in esophageal cancer patients with synchronous solitary brain metastasis

The aim of the present study was to investigate the outcomes of esophageal cancer (EC) patients with isolated synchronous brain oligometastasis (oligo-BM) treated with chemoradiotherapy (CRT) of the primary site and localized treatment of the BM with surgery, radiotherapy (RT) or radiosurgery. Of 125 EC patients investigated, seven patients (6%) had solitary BM. Six patients were diagnosed prior to, and one patient was diagnosed during, treatment. All patients were treated with neoadjuvant chemotherapy and whole-brain RT (WBRT) for BM. All but one patient received definitive CRT with a median RT dose of 50.4 Gy using conventional fractionation RT. The median age at diagnosis was 59 years (range, 48-77 years). Six patients succumbed to mortality, and one continued to receive systemic chemotherapy at the last visit. The median survival time of the patients was 18.9 months (range, 10.0-27.2 months). Median time to progression after completion of the treatments was 8 months (range, 3-9 months). Two patients had progression of the primary tumor, and one patient had progression of the BM. The neurological status of three patients with BM who were identified during the staging work-up did not deteriorate as a consequence of WBRT. In conclusion, the present study has demonstrated that aggressive treatment of the primary tumor and oligo-BM in patients with EC may prolong the survival time

Prognostic Value of Metabolic Response Measured by FDG-PET-CT in Patients with Breast Cancer Liver Metastasis Treated with Stereotactic Body Radiotherapy

OBJECTIVE To investigate the impact of metabolic response measured by 18-fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET-CT) in patients with breast cancer liver metastasis (BCLM) treated with stereotactic body radiotherapy (SBRT). METHODS The medical records of 17 patients with BCLM treated with SBRT between March 2013 and October 2017 were investigated retrospectively. Patients received SBRT for their liver metastasis, and thereafter, a second FDG-PET-CT was performed for response assessment in a median of 4.1 (2.2-8.2) months. A total of 54 Gy in three fractions were delivered to liver metastatic lesions. The standardized uptake value (SUV) and survival rates were evaluated. RESULTS After a median follow-up time of 11.5 (3.2-48.9) months, there was a significant difference between pre- and post-SBRT SUVs (p<0.001). Complete metabolic response was observed in 14 (82%) patients, partial metabolic response was observed in 2 (12%) patients, and stable metabolic disease/progressive metabolic disease was observed in 1 (6%) patient at post-treatment PET-CT. The 1- and 2-year overall survival rates were 68% and 57%, respectively, and the 1- and 2-year progression-free survival rates were 38% and 25%, respectively. CONCLUSION PET-CT is an effective tool for response monitoring in patients with BCLM treated with SBRT