Effect of surface treatment on roughness and bond strength of a heat-pressed ceramic

STATEMENT OF PROBLEM: Bonding ceramic restorations to tooth structure relies on treatment of the ceramic intaglio surface, selection of a suitable resin luting agent, and appropriate treatment of prepared tooth structure. Various ceramic surface treatments have been advocated which produce different topographies and bond strengths, but little information is available to identify the interaction between the resulting surface topography and bond strength. PURPOSE: The purpose of this in vitro study was to evaluate the effect of surface treatments on surface roughness and bond strength to dentin and enamel of a commercially available heat-pressed dental ceramic (IPS Empress). MATERIAL AND METHODS: One hundred heat-pressed ceramic disks were fabricated according to the manufacturer's recommendations. Specimens were divided into 5 groups (n=20) and treated with 1 of the following: (1) etching with 9.5% hydrofluoric acid, (2) 50%, or (3) 60% orthophosphoric acid and airborne-particle abrasion with (4) 50-microm, or (5) 250-microm alumina for 10 seconds. Morphological changes obtained with the surface treatments were investigated with a surface texture analyzer on half of the treated specimens. Two additional specimens from each group were treated and prepared for scanning electron microscopy. The specimens were then used for a bond strength test. The treated specimens were silanated and luted with a composite resin luting agent (Nexus 2) to enamel (n=50) and dentin (n=50) surfaces with 10 specimens for each treatment group. The luted specimens were loaded to failure in a universal testing machine in the shear mode with a crosshead speed of 0.05 mm/min. The data were analyzed with 1-way ANOVA followed by the Ryan-Einot-Gabriel-Welsch Multiple Range Test (alpha=.05). RESULTS: Surface treatments resulted in significant differences for surface topography and shear bond strength (P<.001). Mean surface roughness (Ra) (SD) was (2.54 (0.21) microm) for ceramic surfaces treated with 50-microm aluminum powder. Treatment of ceramic specimens with 50% orthophosphoric acid appeared to result in a smoother surface (1.02 (0.38) microm). The highest mean bond strength (SD) to enamel (14.7 (0.6) MPa) and dentin (8.2 (1.5) MPa) was associated with hydrofluoric acid etching. The lowest mean bond strength (SD) to enamel (2.7 (0.8) MPa) and dentin (1.5 (0.1) MPa) was recorded for 50% phosphoric acid. CONCLUSIONS: Hydrofluoric acid treatment resulted in the generation of pores and grooves that produced the greatest bond strength between the ceramic and tooth dentin and enamel. Orthophosphoric acid treatment was the least effective surface treatment method evaluated. The results are applicable to only the all-ceramic/luting system evaluated.     

湖南省浏阳市农村居民慢性病患病现状及影响因素分析

目的了解湖南省浏阳市主要慢性病的流行状况及其影响因素,为预防控制慢性病提供理论及实践依据。方法采用分层整群抽样的方法在浏阳市抽取3个乡镇,对15岁以上居民进行入户普查,共计调查42 713人。采用描述性流行病学的方法分析浏阳市常住居民健康状况和慢性病患病现状,应用多因素Logistic回归分析探索慢性病的影响因素。结果 2007年浏阳市农村居民慢性病的患病率为21.96%,根据浏阳市农村居民年龄构成标准化后的总患病率为23.42%;患病率居前4位的慢性病为高血压(38.3‰)、肾结石(10.0‰)、冠心病(8.1‰)和慢性支气管炎(5.8‰)。浏阳市农村居民患慢性病的影响因素有体质指数高、高龄、低文化程度、工作不稳定、戒烟和低收入等。结论湖南浏阳市农村地区居民慢性病患病率较高,心脑血管疾病、肾结石是危害居民健康的主要慢性疾病,疾病防控部门应针对浏阳市农村居民患病的危险因素,制定和实施积极的防制措施。     

Hand,Foot and Mouth Disease in the Andaman Islands,India

Objectives

To investigate an outbreak of Hand, foot and mouth disease (HFMD) in Andaman Islands during 2013.

Methods

Epidemiological, clinical data and samples were collected from HFMD patients who attended selected hospitals. Data were analyzed and samples were processed for detection of Enterovirus and further confirmed by sequencing. Serotype-specific molecular typing was also done to identify the etiological agent.

Results

Of the 246 suspected patients, most were affected in August 2013 (92/246, 37.4%). Fever (71.2%) associated with typical HFMD rashes (100%) were the most common presenting symptoms and rashes were mostly distributed on hands (100%), legs (92%), mouth (77%), and buttocks (52.8%). All cases were reported as mild and recovered completely without any complications. Enterovirus was detected in 63 cases (50.4%).

Conclusion

HFMD was mild, mostly reported in children <60 months of age, and in boys. Coxsackie virus A16 was found to be the only etiological agent for this specific outbreak.

     

Allogeneic hematopoietic stem cell transplantation for infants with idiopathic myelofibrosis

IMF is a rare disease in children that can present during infancy and has a protracted course. The only known curative approach for this disease in adult patients is allogeneic HSCT. There are very few reports describing the long‐term outcome of young children following stem cell transplantation for IMF. We report on eight patients less than two yr of age with IMF that did not resolve with supportive care measures. All patients underwent myeloablative conditioning regimen with busulfan and cyclophosphamide ± ATG followed by HSCT from matched related (n = 6) or unrelated donor (n = 2). All patients achieved neutrophil and platelet engraftment. Four patients had grade II‐III acute GVHD, and chronic GVHD developed in five patients (three mild and two severe). At a median follow‐up of eight and a half yr (0.7–9), all patients are alive with complete resolution of their hematologic manifestations. At the last follow‐up, all patients had normal endocrine function except for one patient who developed hypothyroidism. To date, this is the largest cohort of young children with IMF treated successfully with HSCT, with the longest duration of follow‐up. In conclusion, our study showed that HSCT is a curative option for infants with IMF.     

Spectrophotometric and AAS determination of ramipril and enalapril through ternary complex formation

Two sensitive, spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of two antihypertensive agents (enalapril maleate and ramipril). The spectrophotometric procedures for the two cited drugs are based on ternary complex formation. The first ternary complex (copper(II), eosin, and enalapril) was estimated by two methods; the first depends on its extraction with chloroform measuring at 533.4 nm. Beer's law was obeyed in concentration range from 56 to 112 microg ml(-1). The second method for the same complex depends on its direct measurement after addition of methylcellulose as surfactant at the pH value 5 at 558.8 nm. The concentration range is from 19 to 32 microg ml(-1). The second ternary complex (iron(III), thiocyanate, and ramipril) was extracted with methylene chloride, measuring at 436.6 nm, with a concentration range 60-132 microg ml(-1). The direct atomic absorption spectrometric method through the quantitative determination of copper or iron content of the complex was also investigated for the purpose of enhancing the sensitivity of the determination. The spectrophotometric and atomic absorption spectrometric procedures hold their accuracy and precision well when applied to the determination of ramipril and enalapril dosage forms.