Surface characteristics of aesthetic restorative materials - an SEM study

To determine the degree of surface roughness of glass-ionomer cements (GICs) and polyacid-modified resin composite (PAMRC) after polishing and immersion in various foodstuffs. Three tooth-coloured restorative materials were used: a PAMRC (F2000), a conventional glass-ionomer cement (CGIC) (Fuji IX) and a resin-modified glass-ionomer cements (RM-GIC) (Fuji II LC). Disk-shaped specimens were prepared and tested with either a plastics matrix finish or after polishing with wet silicon carbide papers up to 2000-grit. All specimens were immersed in 37 degrees C-distilled water for 1 week, followed by three different foodstuffs (red wine, coffee or tea) for a further 2 weeks. Replicas of specimens were prepared by taking polyvinyl siloxane impressions, casting in epoxy resin, gold sputter-coating and examining using a Field-Emission Scanning Electron Microscope. The polished and matrix finish specimens of F2000 showed many microcracks at low magnification, and eroded surfaces with missing and protruding particles at high magnification in the polished specimens. The surface-polished specimens of Fuji II LC were considerably rougher than the matrix-finish specimens, with large voids and protruding filler particles. The effects of foodstuffs on Fuji II LC and F2000 were not noticeable. The CGIC became noticeably rougher after exposure to coffee and tea. All specimens had the smoothest surface when they were cured against a plastics matrix strip, and all materials had a rougher surface after polishing. None of the foodstuffs produced a perceptible increase in roughness on RM-GIC and PAMRC surfaces, whereas coffee and tea markedly increased the surface roughness of Fuji IX.     

Adsorption of human plasma proteins to modified titanium surfaces

OBJECTIVES: The aim of this study was to examine the effect of modified titanium (Ti) surfaces on the initial events of plasma proteins adsorption. MATERIALS AND METHODS: 'Ti disks' with three types of surface modifications were compared: machined, acid-etched and acid-etched and blasted. Physical and chemical characterizations of the surfaces were performed via scanning electron microscopy (SEM), atomic force microscopy (AFM) used for analysis of surface topography, characterization of the titanium oxide (TiO2) layer was carried out by X-ray photoelectron spectroscopy (XPS) and characterization of surface energy by the determination of contact angles. Evaluation of plasma proteins' adsorption to the treated Ti surfaces was performed by mass spectrometry, confocal laser scanning microscopy and XPS. Quantitative proteins' assessment was carried out by enzyme-linked immunosorbent assay. RESULTS: SEM images revealed major differences in the topography of the examined surfaces. Acid-etched and blasted Ti surfaces were found to have higher roughness values and a thicker TiO2 layer as compared with acid-etched and machined surfaces. Moreover, acid-etched and blasted surfaces showed high surface area differentiation, pointing to a high increase in the three-dimensional (3D) surface area over the 2D surface area compared with the other surfaces. Adsorption of plasma proteins to the acid-etched and blasted Ti surfaces was both qualitatively and quantitatively more intense compared with the machined and acid-etched surfaces. This was shown for each examined protein, total proteins and by the removal degree of the protein coat. CONCLUSIONS: The preferential adsorption of plasma proteins to the acid-etched and blasted Ti surfaces may be explained by its topographical characteristics and by the increase of the 3D surface area of this modified surface.     

Electromyographic activity of masticatory, neck and trunk muscles of subjects with different skeletal facial morphology--a cross-sectional evaluation

The electromyographic pattern activity of masticatory, neck and trunk muscles was assessed using surface electromyography (sEMG) in 60 Caucasian adult females (20 subjects in skeletal class I, 20 subjects in skeletal class II and 20 subjects in skeletal class III), classified on the base of their skeletal class (ANB angle), corrected on the base of maxillary and mandibular rotations. The sEMG activity was recorded at mandibular rest position and during maximal voluntary clenching. At mandibular rest position, the sEMG activities of masseter and anterior temporal muscles were significantly higher in class III subjects than in class I and class II subjects, that showed no significant difference between them. Then, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups. During maximal voluntary clenching, no significant difference was observed in the sEMG activity of masticatory muscles among the three considered groups. However, the sEMG activities of posterior cervicals and upper trapezius were significantly higher in skeletal class III subjects than in the other two groups, which showed no significant difference between them. In conclusion, the skeletal class seems to affect the sEMG pattern activity of masticatory, neck and trunk muscles.     

Task-related electromyographic spectral changes in the human masseter and temporalis muscles

The masticatory muscles differ in their fiber type composition. It can therefore be expected that their electromyographic (EMG) power spectra will differ during the performance of different bite force tasks. In the present study, surface EMG activity was picked up from the masseter and from the anterior and posterior temporalis muscles of nine adult subjects. At a bite force level as low as 25 N, the mean power frequency (MPF) values of the posterior temporalis were significantly lower than those of the masseter and anterior temporalis. The MPF values of the masseter muscles decreased with an increase of bite force magnitude, whereas the MPF values of the anterior and posterior temporalis did not change significantly. The MPF values were significantly influenced by the direction of bite force. The observed changes of MPF are possibly related to the recruitment of different fiber types, and support the concept that the masticatory muscles behave heterogeneously.     

The Bond Strength of an Adhesive Resin Luting Cement to a Variety of Surface Treatments of a High-Palladium Copper Alloy

Purpose This study evaluated the tensile bond strength of a bisphenol glycidyl methacrylate (Bis-GMA) resin luting cement with four different surface treatments of a high Pd-Cu alloy. Materials and Methods For each surface treatment type (tin-plated, porcelain furnace oxide, air-abraded, and finished-only), 15 opposing half-dumbbell-shaped samples were cast and prepared in new Pd?Cu alloy. Samples were luted with a Bis-GMA resin luting cement at a film thickness of 80 μm using a custom alignment apparatus. Samples were stored in distilled water at 37°C for 24 hours, thermocycled for 1,000 cycles, and then stored for 30 days in distilled water at 37°C. Samples were then subjected to fracture in tension at a loading rate of 0.5 cm/min with the bond strengths calculated in megapascals (MPa). The fractured surfaces were examined using stereomicroscopy and scanning electron microscopy at various magnifications ranging from 5.5x to 500x to determine the type of bond failure (adhesive, cohesive, or mixed). Results Tensile bond strengths (mean ± SD MPa) were: tin-plated, 30 ± 15.7; porcelain furnace oxide, 23 ± 8.6; air-abraded, 8 ± 8.1; and finished-only, 4 ± 4.5. Statistical analysis of the tensile bond values using an ANCOVA and Tukey's multiple comparison test at a significance level of 0.05 indicated that there was no difference between the tin-plated and the furnace oxide groups, as well as between the air-abraded and the furnace oxide groups. However, there was significant difference between the tin-plated, the air-abraded, and the finished-only groups. The observed bond failures were predominantly mixed and cohesive in nature with only one adhesive failure. Conclusions There was no significant difference in the tensile bond strengths between the tin-plated group or the porcelain furnace oxide surface group. This suggests that the less-technique-sensitive porcelain furnace oxide surface treatment offers an alternative for achieving high metal-resin bonds to a high Pd?Cu alloy.     

Fluoride profiles in different sites of approximal surfaces of second primary molars after topical application of acidulated phosphate fluoride gel in vivo

Thirty-four (17 paired) extracted second primary molars were obtained from 17 individuals (9 boys and 8 girls) aged from 9 yr 2 months to 12 yr 7 months. A tooth on one side was extracted as a control, and an acidulated phosphate fluoride (APF) gel was then applied to the paired contralateral second primary molar. Three months later, the experimental tooth was extracted. Nine sites were assayed by a microsarapling technique from small areas of the approximal enamel surface. The fluoride and phosphorus concentrations were determined by a fluoride electrode and by colorimetric procedure, respectively. Fluoride concentrations were higher in the teeth treated with the APF gel than in the control teeth. The highest fluoride uptake was observed in the central area of the approximal surfaces. Deeper areas (>10 μm) had a marked uptake of fluoride as compared with surface areas (< 3 μm). It was concluded that the APF gel application increased the fluoride levels of approximal tooth surfaces, particularly the mid-central site, of second primary molars, even at 3 months after application.     

Effect of access cavity location and design on degree and distribution of instrumented root canal surface in maxillary anterior teeth

AIM: The null hypothesis tested in this study was that in single-rooted anterior teeth with simple root canal anatomy, different access cavity designs ('lingual cingulum', 'lingual conventional', 'incisal straight-line') do not influence the ability of endodontic files to plane the walls of the root canals. METHODOLOGY: Thirty extracted human maxillary anterior teeth were divided randomly into three groups for each access cavity. The access cavities were prepared according to predefined criteria and the roots embedded in individual polyvinyl-siloxane putty matrices. The matrices allowed these teeth to be split into buccal and palatal halves and to be reassembled. The split teeth enabled removal of pulpal remnants from the root canal system and the walls to be stained with an even layer of permanent black ink. Once dried, the split roots were reassembled in the putty matrices and a step-back filing technique was used to prepare the canals with water irrigation. The canal walls were examined for residual ink staining and scored by three independent assessors using an index devised for the purpose. RESULTS: There was good agreement between the assessors. None of the access cavities allowed file contact with the entire root canal wall. The overall (palatal and buccal sections) scores showed significant differences (P < 0.01) between the access cavity groups in the extent to which the canal walls could be filed. The straight-line incisal access cavity had the greatest proportion of instrumented root canal surface. The lingual cingulum access cavity was the worst in this respect. The differences in residual ink scores between the access cavity types were significant for the buccal halves (P < 0.01) but not for the palatal halves (P > 0.05). CONCLUSIONS: The null hypothesis was proven. Regardless of access cavity design, mechanical preparation did not allow instrumentation of the entire root canal wall. Straight-line access allowed the greatest proportion of the root canal wall to be instrumented and the lingual cingulum access the least.     

超声乳化术对伴有睑板腺功能障碍的白内障患者眼表的影响

目的:观察超声乳化术对伴有睑板腺功能障碍(MGD)的白内障患者眼表功能的影响。方法:前瞻性队列研究。选取金华文荣医院2016年3月至2018年2月伴有MGD的白内障78例(81眼),均行超声乳化人工晶状体植入术。术后随访3个月观察眼表功能。结果:术后3天泪液分泌情况(SIt)、泪膜破裂时间(BUT)高于术前1天(P<0.05);术后3个月的SIt、BUT高于术前1天,P<0.05,低于术后3天(P<0.05)。睑板腺分泌物形态:术前1天与术后3天相比,差异无统计学意义(P>0.05);术后3天与术后3个月相比,差异无统计学意义(P>0.05);术前1天与术后3个月相比,差异有统计学意义(P<0.05)。结论:伴有MGD的白内障患者超声乳化术后依旧出现眼表功能障碍,随访至术后3个月,并未见明显恢复。     

Randomized masked trial of the clinical efficacy of MGO Manuka Honey microemulsion eye cream for the treatment of blepharitis

PurposeTo assess the clinical efficacy of a novel MGO Manuka Honey microemulsion (MHME) eye cream for the management of blepharitis.MethodsFifty-three participants (32 females, 21 males; mean ± SD age, 60 ± 12 years) with clinical signs of blepharitis were enrolled in a prospective, investigator-masked, randomized, paired-eye trial. The MHME eye cream (Manuka Health New Zealand) was applied to the closed eyelids of one eye (randomized) overnight for 3 months. Visual acuity, ocular surface characteristics, symptoms and tear film parameters were assessed at baseline, day 30, and day 90. Eyelid swab microbiology cultures were evaluated at baseline and day 90.ResultsBaseline measurements did not differ between treated and control eyes (all p > 0.05). Significant reductions in SANDE and SPEED symptomology scores were detected in treated eyes on days 30 and 90 (all p < 0.05), while clinical improvements in non-invasive tear film breakup time, lipid layer thickness, and inferior lid wiper epitheliopathy were observed on day 90 (all p < 0.05). Following the 3-month treatment period, ocular Demodex, Corynebacterium macginleyi, Propionibacterium acnes, and Staphylococcus epidermidis load decreased significantly in treated eyes (all p ≤ 0.001). There were no changes in visual acuity during the 90-day period (all p > 0.05), and no major adverse events were reported.ConclusionTopical overnight application of the MHME eye cream effected significant improvements in ocular surface symptomology, tear film stability and lipid layer thickness, and reduced lid margin staining, ocular Demodex and bacterial load. The favourable clinical efficacy and tolerability profile suggests promise for the MHME eye cream as a treatment for blepharitis management.Trial registration numberACTRN12616000539437.     

冠状切口治疗复杂面中部骨折的疗效探讨

目的:探讨冠状切口手术治疗在复杂面中部骨折的临床治疗优势。方法:对我科应用冠状切口治疗复杂面中部骨折的36例患者进行回顾研究,比较其与传统方法的优势。结果:术后6个月,手术切口大多数都已愈合,无血肿,基本上无感染。瘢痕不明显,面中部外形对称,没有出现面神经损伤症状,头皮切口处毛发大多正常生长。骨折复位状况愈合良好,咬合关系、开口度正常,患者较为满意。结论:冠状切口手术能够有效的防止并发症出现,充分暴露手术视野,切口隐蔽,瘢痕不明显,值得临床推广应用。