Microtensile Bond Strength of Self-Etch Adhesives on Dentin Treated with Chlorhexidine.

AIM: To evaluate the microtensile bond strength of self-etching adhesive systems in dentin treated with 2% chlorhexidine digluconate (CHX). MATERIALS AND METHODS: The occlusal surfaces of 20 human molars were removed and divided into eight groups: 1A, Clearfil SE adhesive (SE) with self-etching technique (TS); 1B, SE with TS and previous application of CHX; 2A, Scotchbond Universal (SBU) adhesive with TS; 2B, SBU adhesive with TS and previous application of CHX; 1C, SE with total-etching technique (TT); 1D, SE with TT and previous application of CHX; 2C, SBU with TT; 2D SBU with TT and previous application of CHX. Composite resin (5mm) was applied on the hybridized surface. Samples were subjected to microtensile test and evaluated on Scanning Electron Microscope (SEM) and with energy-dispersive X-ray (EDX). RESULTS: Low values of bond strength were observed in groups 1A (39,77±11,56) and 2A (40,84±12,49) comparing with 1B (22,86±5,18) and 2B (27,02±5,58). TS group presented adhesive type remover fracture while TT groups presented cohesive at the top of hybrid layer. EDX revealed the presence of CHX crystals for TS, which was not found in the TT. CONCLUSION: The previous application of chlorhexidine on dentin decreased the bond strength of adhesive systems on self-etching technique.

Tomographic analysis of nasomaxillary and zygomaticomaxillary buttress bone thickness for the fixation of miniplates.

The purpose of this study was to evaluate the bone thickness of the nasomaxillary and zygomaticomaxillary buttresses to identify the most favourable region for the installation of miniplates. Bilateral tomographic images of 103 individuals were evaluated, for a total of 206 nasomaxillary and zygomaticomaxillary buttresses. Measurements of bone thickness were performed in the parasagittal reconstructions along three vertical lines on the nasomaxillary buttress (21 measurement points) and four vertical lines on the zygomaticomaxillary buttress (28 measurement points). The vertical line measurements for each buttress were compared using the Kruskal-Wallis test. Spearman's correlation coefficient was used to determine the correlation between the thicknesses obtained and patient sex and side (right/left). The level of significance adopted was 5%. The nasomaxillary and zygomaticomaxillary buttresses presented statistical differences in thickness at their respective points (P=0.001). The analysis of the nasomaxillary buttress showed that the thicker bone for the installation of miniplates follows the long axis of the upper canine at a distance of 3mm from the root apex. For the zygomaticomaxillary buttress, thicker bone to install miniplates was found distal to the distobuccal root of the first molar, at a distance of 3.5mm from the limit of the infraorbital foramen.

Influence of Cone-Beam Computed Tomography filters on diagnosis of simulated endodontic complications.

AIM: To evaluate the influence of cone-beam computed tomography (CBCT) filters on diagnosis of simulated endodontic complications. METHODOLOGY: Sixteen human teeth, in three mandibles, were submitted to the following simulated endodontic complications: (G1) fractured file, (G2) perforations in the canal walls, (G3) deviated cast post, and (G4) external root resorption. The mandibles were submitted to CBCT examination (I-Cat® Next Generation). Five oral radiologists evaluated the images independently with and without XoranCat® software filters. Accuracy, sensitivity and specificity were determined. ROC curves were calculated for each group with the filters, and the areas under the curves were compared using anova (one-way) test. McNemar test was applied for pair-wise agreement between all images versus the gold standard and original images versus images with filters (P < 0.05). RESULTS: G1 was the most difficult endodontic complication to diagnosis, followed by G2, G4 and G3. There were no differences between areas under the ROC curves for the filters in all groups; however, Sharpen Super Mild filter had the best results for G1 (0.47), Angio Sharpen Low 3 × 3 for G2 (0.93), Angio Sharpen Low 3 × 3, S9, Shadow and Sharpen for G3 (1.00) and Sharpen 3 × 3 for G4 (1.00). The McNemar test revealed significant differences between all filters with the gold standard (P = 0.00 for all filters) and the originals images (P = 0.00 for all filters) only in G1 group. There were no differences in the other groups. CONCLUSIONS: The filters did not improve the diagnosis of the simulated endodontic complications evaluated. Their diagnosis remains a major challenge in clinical practice.

Evaluation of temporomandibular joint disc displacement as a risk factor for osteoarthrosis.

Temporomandibular joint (TMJ) disc displacement is a clinical sign often found in patients with temporomandibular disorders (TMDs) and associated with TMJ osteoarthrosis. Osteoarthrosis is a degenerative joint disease that may be associated with pain and functional disability. The aim of this study was to evaluate the odds ratio (OR) of joints with disc displacement presenting osteoarthrosis via magnetic resonance imaging (MRI) analysis. In total, 224 TMJ images from patients with signs and symptoms of a TMD were evaluated. The OR, a measure of association, was used to calculate the likelihood of TMJ disc displacement (with or without reduction) with osteoarthrosis. Joints with anterior disc displacement with reduction (ADDwR) and anterior disc displacement without reduction (ADDwoR) were 2.73- and 8.25-times, respectively, more likely to have osteoarthrosis. A nine-times greater likelihood of osteophyte occurrence was observed in cases of ADDwoR, whereas a lower OR for their occurrence (OR 2.96) was observed in cases of ADDwR. The significant OR of joints with disc displacement presenting osteoarthrosis, particularly in cases of ADDwoR, emphasizes the importance of accurate assessment of changes in disc position, which may be associated with other painful and functional disorders of the TMJ.

Influence of maxillomandibular positioning in cone beam computed tomography for implant planning.

The aim of this study was to evaluate the influence of changes in maxillomandibular positioning during cone beam computed tomography (CBCT) imaging on the planning of dental implants. Ten skulls were marked bilaterally with metal spheres in four regions: incisors, canine, premolars, and molars. CBCT scans were obtained in seven positions: standard position (SP), displacements of 10° and 20° above and below the SP, and lateral displacements of 10° and 20° from the SP. Subsequently, bilateral measurements of the height and width of the maxilla and mandible were performed on all images. The results showed that the position with a displacement of 20° above the SP presented the greatest differences in the measurements of bone height and width. In the bilateral comparisons, the maxillary bone width showed the greatest differences, especially for the regions of the premolars and molars. It is concluded that alterations of positioning during the acquisition of CBCT images can lead to alterations in the measurements of bone height and width, which may result in errors in implant planning and cause damage to anatomical structures.