Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The aim of this study was to evaluate the whitening and abrasion effects of dentifrices containing different whitening agents on artificially stained and unstained enamel. 160 human dental enamel discs were distributed into four groups according to the type of dentifrices applied on them (n=40): Group I, non-whitening dentifrice (control group); Group II, dentifrice containing charcoal; Group III, dentifrice containing blue covarine; Group IV, dentifrice containing hydrogen peroxide. Half of the specimens in each group were immersed in coffee solution. Color measurements were evaluated from stained and unstained specimens before and after brushing by a spectrophotometer. The surface roughness of each unstained specimen was analyzed using a profilometer after the brushing and bleaching. The surface of one randomly selected specimen from each group was observed using a scanning electron microscope (SEM). Statistical analysis of the color change was performed using the Kruskal-Wallis test. The one-way ANOVA was used to evaluate surface roughness. Group III provided significantly higher recovery on ∆E00 values than other groups on the unstained enamel (p<0.05). Group IV showed significantly the highest ∆E00 values on stained enamel (p<0.05) and also Group IV showed the highest surface roughness values (p<0.05), SEM revealed a more irregular surface in groups III and IV. It can be stated that dentifrice containing blue covarine is both an effective and a safe way to provide whiter teeth with routine home tooth brushing.

The objective is to determine which biopolymer has the best 3D printing characteristics and mechanical properties for the manufacture of a bioscaffold, using the fused deposition printing technique, with models generated from an STL file obtained from a Micro-CT scan taken from a bovine iliac crest bone structure. Through an experimental exploratory study, three study groups of the analyzed biopolymers were carried out with thirteen printed structures of each one. The first is made of 100% PLA. The second, 90B, we added 1g of diatom extract, and the third, 88C, differs from the previous one in that it also contains 1g of calcium phosphate. The 39 printed structures underwent a visual inspection test, which required the fabrication of a gold standard scaffold in resin, with greater detail and similarity to the scanned bone structure. Finally, the structures were subjected to a compressive force (N) to obtain the modulus of elasticity (MPa) and compressive strength (MPa) of each one of them. A statistically significant difference (p=0.001) was obtained in the printing properties of the biomaterial 88C, compared to 90B and pure PLA and the 88C presented the best 3D printing characteristics. In addition, it also  presented the best mechanical properties compared to the other groups of materials. Although the difference between these was not statistically significant (p=0.388), in the structures of the 88C biomaterial, values of compressive strength (8,84692 MPa) and modulus of elasticity (43,23615 MPa) were similar to those of cancellous bone in the jaws could be observed. Because of this result, the 88C biomaterial has the potential to be used in the manufacture of bioscaffolds in tissue engineering.

To examine the colour change and surface roughness of giomer, microhybrid composite and nanohybrid composite after brushing with whitening toothpastes. Disc-shaped samples of giomer, microhybrid composite and nanohybrid composite were divided into three subgroups(n=10), with the initial colour measured with a spectrophotometer and the surface roughness measured with a mechanical profilometer. The samples, which were immersed in coffee solution were brushed once a day with whitening toothpastes (Opalescence Cool Mint (OCM), Colgate Optic White Extra Power (COW) and Signal White Now Gold (SWN)) for 12 days. Colour change and surface roughness were measured again after the colouring-brushing cycle. All of the analyses were performed using appropriate statistical hypothesis tests. The highest increase in surface roughness was seen in the microhybrid composite group applied with SWN (p<0.05). The group with the least increase was the giomer group applied with SWN (p<0.05). While the least colour change was observed in the COW applied nanohybrid composite group (∆E00=1,814), the most colour change occurred in the COW applied giomer group (∆E00=5.943). After the use of whitening toothpastes, the roughness of giomer, microhybrid composite and nanohybrid composite surfaces was increased and a colour change above the clinically accepted value was observed.

To evaluate whether the WaveOne Gold and Reciproc single file instrumentation systems, are effective in reducing the microbial load of a mixed biofilm and the cleaning of apical third compared to the Twisted File Adaptive system (multiple-file system). Seventy mesial roots of the first and second molars were included and randomly divided into three experimental groups (n=20, n=10 controls). Biofilms were formed inside canals over 31 days. After instrumentation with the unique file systems, WaveOne Gold and Reciproc and the multiple file system Twisted File Adaptive, using 2.25% sodium hypochlorite as an irrigant in all cases, a count of colony forming units was performed using serial dilutions, cleaning of the apical third was evaluated using scanning electron microscopy. Comparisons amongst groups were made by using parametric and non-parametric statistics, according to a normal or non-normal data distribution, respectively.  No significant differences in the reduction of the microbial load after employing a single-file system in comparison to the multiple-file system were found; in addition, the cleaning of the apical third was similar for the three different instrumentation systems. The single-file system is equal in effectiveness compared with the multiple-file system in reducing the microbial load.

Mucoepidermoid carcinoma (MC) is the most common malignant epithelial neoplasm in the salivary glands. This neoplasm has varying proportions of mucous, epidermoid, intermediate, columnar, and clear cells. MCs have been associated with CRTC1-MAML2 genes; however, their pathogenesis is uncertain. Recently, epigenetic changes have been considered a possible aetiologic factor. To identify the methylation state of RB, P16, MGMT, and hMLH genes in the three severity grades of MC were used five MCs and one healthy minor salivary gland as a control group (CG) obtained from the Pathology and Oral Medicine Laboratory and analyzed using MS-PCR to compare the presence or absence of methylation in promotor regions. The Kruskal-Wallis test was performed, with p≤0.05 considered significant. CG was employed as the normalizer of methylation levels. All assays were performed in triplicate. The mean age of our population was 52.6±18.6 years old; the total population was female and included 2 low grade, 2 intermediate grade, and 1 high grade levels of severity. When comparing the methylation status of the three histopathological grades of MC against the control, statistically significant differences were observed in Rb-M, MGMT-M, and hMLH-1-NM for high-grade severity, with p values of 0.03, 0.05, and 0.04, respectively. Methylation is a possible mechanism for pathogenesis processing of high-grade MC. However, a larger sample population is necessary to validate this finding.

Cells undergo autophagy to save themselves from injury, but progressive autophagy can cause cell death. This study characterized and compared the effect of grape (resveratrol) and tomato (lycopene) extracts and their combination on modulating autophagy-related miRNA and its target gene in squamous cell carcinoma cell line. Docking analysis for extracts and selected genes was performed. Methyl Thiazol Tetrazolium assays were used to assess the cytotoxicity of extracts and their combination toward HEp-2 cells. qRT-PCR was used to quantify changes in gene expression. Data were statistically analyzed. miRNA-20a was identified as a potential effector in laryngeal cancer, and sequestosome-1 (SQSTM1) was its target gene. Docking analysis showed that resveratrol interacted with miRNA-20a and showed less affinity toward SQSTM1. Hydrogen bonds and hydrophobic interactions were predicted. In contrast, lycopene showed less affinity toward miRNA-20a than resveratrol. Increasing doses of resveratrol, lycopene, and their combination induced a statistically significant reduction in mean percent viability and mean fold changes of miRNA-20a and SQSTM1 expression in treated HEp-2 cells. Pearson’s correlation showed a statistically significant positive correlation between miRNA-20a and SQSTM1 (R=0.812, p≤0.001). Grape and tomato extracts and their combination display promising cytotoxicity against HEp-2 cells in a dose- and time-dependent fashion. Both extracts reduce the expression of miRNA-20a and SQSTM1 with subsequent inhibition autophagy and promotion of apoptosis in HEp-2 cells.  

Electromyography (EMG) is used for the measurement of muscle activity to characterize the nature of muscle contraction in Oral submucous fibrosis (OSMF). Aim:  To assess the efficacy of EMG in evaluating masseter muscle activity in the management of OSMF. This review identified 73 records from standard databases which were rigorously screened with eligibility criteria and 3 clinical studies were identified based on our inclusion criteria. The quality of included studies was assessed by the PEDro scale and data was synthesized with detailed characterization. The Risk of Bias assessment among studies was done using the ROBINS-I tool and a meta-analysis could not be done due to high clinical heterogeneity. Our result recommends that EMG be used as an objective prognosis assessment tool by quantifying the management of OSMF irrespective of the intervention applied. However, it is not to be considered the gold standard as of now with limited data pooled and needs to be further assessed with clinical trials.  EMG can be advocated as a reliable adjunct assessment for measuring the interventional outcome of OSMF irrespective of treatment modalities.

The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on evaluation of root canal preparation using rotary heat-treated nickel-titanium files. Curved mesial root canals of mandibular molars were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM) (n=12). The specimens were scanned using micro-CT with 5μm of voxel size before and after root canal preparation. Images with sub-resolution of 10 and 20μm voxel sizes were obtained. The percentage of volume increase, debris and uninstrumented root canal surface were analyzed in the different voxel sizes. Data were compared using unpaired Student’s t-test and ANOVA statistical tests (α=0.05). No differences were observed for percentage of volume increase, debris and instrumented surface between the root canals prepared by PDL and HEDM (p>0.05).  Both systems promoted higher percentage of debris in the apical third compared to the middle third (p<0.05). After instrumentation using PDL the percentage of uninstrumented surface was highr in the apical third than middle third only when analysis were performed at 5µm (p<0.05). When comparing the different voxel sizes (5,10 or 20µm), both groups showed different means for the variables, with no significant difference (p>0.05). PDL and HEDM had similar root canal preparation capacity. Micro-CT images using different voxel sizes did not influence the results of volume increase and debris evaluation. However, images at 5µm showed greater accuracy to evaluate the percentage of uninstrumented surfaces.

This study aimed to analyze the effect of several final irrigation protocols on tubular permeability and push-out bond strength of an epoxy resin-based cement to radicular dentin. The crowns of 110 human teeth were removed to standardize at 17mm in length. The root canals were instrumented and irrigated with 5ml of 5% NaOCl and 17% EDTA. The samples were then randomly divided into 5 groups (n=22) according to the final irrigation protocol. Subsequently, the samples were subdivided into two different groups to assess dentin permeability or the evaluation of the push-out bond strength. In Group 1, all samples displayed the formation of brown-like precipitates. Group 2 and Group 5 demonstrated cleaner dentin walls. The push-out bond test after 72 hours denoted a significant difference when comparing Group 1 vs Group 2 and Group 1 vs Group 3. After thermocycling, a significant difference is observed between Group 1 and all remaining groups. The irrigation protocol using distilled water prior to irrigation with chlorhexidine significantly reduces the formation of intracanal precipitates by avoiding interactions between irrigants. The push-out bond strength of epoxy resin-based cement is directly influenced by the precipitates formed in the root canal after irrigation and the time of thermocycling. 

The aim of this study was to compare the filling capacity in curved root canal using a new continuous wave of condensation technique (Termo Pack II, Easy Dental Equipments, Brazil) or lateral compaction. The percentage of voids in the filling of mesial root canals of mandibular molars was assessed by micro-computed tomography (micro-CT). Mesial root canals (n=24) of mandibular molars with a degree of curvature between 20° and 40° were prepared using rotary system (ProDesign Logic, Easy, Brazil) up to #35, .05 taper. The root canals were filled by using the continuous wave of condensation system or lateral compaction and AH Plus sealer (n=12). Scanning at 9 µm was performed after preparation and after filling by using micro-CT SkyScan 1176. The volumetric percentage of filling material and voids (total length and in each root canal third) were calculated. Data were analyzed using ANOVA/Tukey and Student’s t tests (α=0.05). Before the filling techniques, the root canals volume after preparation was similar (p>0.05). The root canals filled by the continuous wave of condensation technique presented the lowest percentage of voids, and the greatest percentage of filling material in total length and thirds (cervical, middle and apical) (p<0.05). Both techniques were not able of completely filling the root canals. The continuous wave of condensation technique Termo Pack II promoted better root canal filling in curved root canals, when compared with lateral compaction.