Caries Lesion Assessment Using 3D Virtual Models by Examiners with Different Degrees of Clinical Experience.

Background and Objectives: Dental caries is a preventable, reversible disease in its early stages. This study evaluated the intra-rater agreement of International Caries Assessment and Detection System (ICDAS) scores with Medit i500® and Omnicam® scanners versus traditional clinical examinations and the inter-rater agreement using the Omnicam® among senior dentists and dental students and between these two groups. Materials and Methods: A total of 24 patients aged between 21 and 34 years, randomly selected from dental students and interns, underwent four examinations (three intraoral scans and one clinical examination), and the corresponding ICDAS scores were recorded by a randomly selected rater out of the 31 available examiners. The examination team consisted of dental students, dentists with less than 3 years, and dentists with more than 5 years of clinical experience. The following inter- and intra-rater agreement tests for the ordinal data were chosen: Fleiss' kappa coefficient, Cohen's weighted kappa, and inter-class correlations. Results: For all examination techniques, there was statistically significant agreement for the experienced raters (p < 0.05). The highest positive interclass correlation was obtained for inter-rater agreement tests of 288 observations recorded by senior dentists: ICC = 0.969 (95% CI 0.949-0.981). Conclusions: Intra-rater reliability was excellent for Omnicam compared to clinical exams conducted by senior dentists but moderate for Medit i500. Although inter-rater agreement using Omnicam was poor between students and between senior dentists and students, it was excellent among senior dentists.

A New Detection Method of Oral and Oropharyngeal Squamous Cell Carcinoma Based on Multivariate Analysis of Surface Enhanced Raman Spectra of Salivary Exosomes.

Raman spectroscopy recently proved a tremendous capacity to identify disease-specific markers in various (bio)samples being a non-invasive, rapid, and reliable method for cancer detection. In this study, we first aimed to record vibrational spectra of salivary exosomes isolated from oral and oropharyngeal squamous cell carcinoma patients and healthy controls using surface enhancement Raman spectroscopy (SERS). Then, we assessed this method's capacity to discriminate between malignant and non-malignant samples by means of principal component-linear discriminant analysis (PC-LDA) and we used area under the receiver operating characteristics with illustration as the area under the curve to measure the power of salivary exosomes SERS spectra analysis to identify cancer presence. The vibrational spectra were collected on a solid plasmonic substrate developed in our group, synthesized using tangential flow filtered and concentrated silver nanoparticles, capable of generating very reproducible spectra for a whole range of bioanalytes. SERS examination identified interesting variations in the vibrational bands assigned to thiocyanate, proteins, and nucleic acids between the saliva of cancer and control groups. Chemometric analysis indicated discrimination sensitivity between the two groups up to 79.3%. The sensitivity is influenced by the spectral interval used for the multivariate analysis, being lower (75.9%) when the full-range spectra were used.

Nanoscale Investigation of DNA Demethylation in Leukemia Cells by Means of Ultrasensitive Vibrational Spectroscopy.

DNA methylation is a crucial epigenetic hallmark of cancer development but the experimental methods able to prove nanoscale modifications are very scarce. Over time, Raman and its counterpart, surface-enhanced Raman scattering (SERS), became one of the most promising techniques capable to investigate nanoscale modifications of DNA bases. In our study, we employed Raman/SERS to highlight the differences between normal and leukemia DNA samples and to evaluate the effects of a 5-azacytidine treatment on leukemia cells. To obtain spectral information related to DNA base modifications, a DNA incubation step of 4 min at 94 °C, similar to the one performed in the case of RT-PCR experiments, was conducted prior to any measurements. In this way, reproducible Raman/SERS spectra were collected for all genomic DNA samples. Our Raman results allowed discrimination between normal and cancer DNAs based on their different aggregation behavior induced by the distinct methylation landscape present in the DNA samples. On the other hand, the SERS spectra collected on the same DNA samples show a very intense vibrational band located at 1008 cm-1 assigned to a rocking vibration of 5-methyl-cytosine. The intensity of this band strongly decreases in cancer DNA due to the modification of the methylation landscape occurring in cancers. We believe that under controlled experimental conditions, this vibrational band could be used as a powerful marker for demonstrating epigenetic reprogramming in cancer by means of SERS.

In vitro evaluation of root canal preparation with two rotary instrument systems - Pro Taper and Hero Shaper.

BACKGROUND AND AIMS: The purpose of this study was to compare several parameters of root canal preparation using two different rotary Nickel-Titanium instruments: Pro-Taper (Dentsply Maillefer, Ballagigues, Switzerland) and Hero-Shaper (Micro Mega, Besancon, France). METHODS: Twelve extracted maxillary premolars were randomly divided into two groups and embedded into a muffle system. All root canals were prepared to size 25 using Pro-Taper or Hero-Shaper rotary instruments. The following parameters were evaluated: root canal form, centering capacity of the instrument, the presence of residual dentinal debris and smear layer on the root canal walls, working time and the occurrence of intraoperative accidents. Statistical analysis was performed using the chi(2) test (p=0.05). RESULTS: The majority of the root canals prepared with Hero Shaper (88.89%) and ProTaper (77.78%) showed a round or oval cross-section postoperatively. Superposition of pre- and postoperative photographs of the cross-sections showed that for the coronal third of the root canals the Hero Shaper performed in a superior manner, while for the apical third better results were obtained with the Pro Taper system. Cleanliness of the root canal walls was investigated under the SEM, in the middle third of the canal, using a five-score system for debris and smear layer. For debris Hero Shaper and Pro Taper rotary systems achieved 66.67% and 50% scores of 1 or 2, respectively. The results for the smear layer were similar: cleaner root canal walls were found after preparation with Hero Shaper (66.67% scores 1, 2), followed by Pro Taper (50%). Mean working time was shorter for Hero Shaper (124s) than for Pro Taper (184s); the difference was not significant. CONCLUSIONS: Within the limits of this study, both systems had almost the same cleaning ability and excellent centering capacity.

Effect of Cimetidine on Nitro-Oxidative Stress in a Rat Model of Periodontitis.

BACKGROUND AND AIMS: Periodontitis is a chronic inflammation that involves nitro-oxidative stress with damaging periodontal structural effects. We aimed to evaluate the consequences of low-dose cimetidine on nitro-oxidative stress in periodontitis. METHODS: A rat model of ligature-induced periodontitis was used. After two weeks, the periodontitis groups were treated with cimetidine, aminoguanidine, N-nitro-L-arginine methyl ester and trolox for one week. On day 21, blood was drawn and the serum analyzed for measurement of total nitrites and nitrates, total oxidative status, total antioxidant response, and oxidative stress index. RESULTS: Cimetidine had an inhibitory effect on the synthesis of nitric oxide (p=0.001), total oxidative status (p=0.01) and oxidative stress index (p=0.01). Total antioxidant reactivity was increased by cimetidine (p=0.01). The effects of cimetidine were almost like those of aminoguanidine, NG-nitro-L-arginine methyl ester, and trolox. CONCLUSIONS: Low-dose cimetidine can be used as adjunctive host modulatory therapy in chronic periodontitis because it reduces nitro-oxidative stress.