The purpose of this study was to evaluate the clinical performance of preformed beta-quartz glass-ceramic insert restorations.
Nine Class I and 30 Class II beta-quartz glass-ceramic insert restorations were placed in 16 patients who were seen regularly by personnel at Umeå University Dental School. The California Dental Association criteria were used to evaluate the restorations at baseline, 6 months, and 1, 2, and 3 years after luting. The occurrence of postoperative sensitivity, the time taken to manufacture each restoration, and certain periodontal conditions were also evaluated.
Sixty-nine percent of the restorations were rated satisfactory at the 3-year examination. During the follow-up period, 4 became loose and 7 were fractured or had flaking surfaces. Caries was registered in connection with 1 restoration. Excellent ratings were obtained for marginal integrity, anatomic form, surface, and color in 62%, 84%, 32%, and 44% of the restorations, respectively. There was no statistically significant difference in the occurrence of plaque and bleeding on probing in comparison with the controls. The mean overall time for placement was 38 minutes. The estimated survival rate (Kaplan-Meier) was 59% after 3.5 years.
The quality of the beta-quartz glass-ceramic restorations in the present study was inferior to that presented in most earlier studies of ceramic or resin composite posterior restorations placed in patients treated at university clinics. Both the technique and the beta-quartz glass-ceramic inserts have to be evaluated in more long-term studies to assess the possibility of their serving as an alternative restorative technique.
The aim of this retrospective study was to record patients' satisfaction with fixed metal ceramic bridges and crowns made by dental students and to evaluate the functioning and condition of the bridges and crowns clinically and radiologically. Out of the 60 patients treated at the Institute of Dentistry during 1984-85, 30 patients attended the follow-up examination (16 women, mean age 39, range 23-62 years and 14 men, mean age 44, range 26-65 years). The anamnestic data and data regarding treatment procedures were collected from the patient files. The patients had been supplied with 41 crowns and 24 bridges (mean 3.9 units, range 3-6 units), which included 61 abutments and 33 pontics or cantilever extensions (abutment/pontic ratio 1.85: 1). Marginal fidelity was unsatisfactory in 13% of the crowns and bridges and gingival bleeding and pockets of 4-6 mm were noted in 27% and 12% of cases, respectively. None of the subjects had caries in the abutments.
Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from The National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations.
In this prospective cohort study, the authors gathered information from clinicians and offices participating in the network. Clinicians completed a baseline data collection form at the time of restoration placement and annually thereafter. Data collected included patient factors, practice factors and dentist factors, and the authors analyzed them by using mixed-model logistic regression.
A total of 226 practitioners followed up 6,218 direct restorations in 3,855 patients; 386 restorations failed (6.2 percent) during the mean (standard deviation) follow-up of 23.7 (8.8) months. The number of tooth surfaces restored at baseline helped predict subsequent restoration failure; restorations with four or more restored surfaces were more than four times more likely to fail. Restorative material was not associated significantly with longevity; neither was tooth type. Older patient age was associated highly with failure (P
Cites: J Am Dent Assoc. 2005 Jun;136(6):790-616022046
OBJECTIVE: For long-term stability the adhering interfaces of an implant-retained supraconstruction of titanium/carbon-graphite fiber-reinforced (CGFR) polymer/opaquer layer/denture base polymer/denture teeth must function as a unity. The aim was to evaluate adhesion of CGFR polymer to a titanium surface or CGFR polymer to two different opaquer layers/with two denture base polymers. MATERIALS AND METHODS: Titanium plates were surface-treated and silanized and combined with a bolt of CGFR polymer or denture base polymer (Probase Hot). Heat-polymerized plates of CGFR polymer (47 wt% fiber) based on poly(methyl methacrylate) and a copolymer matrix were treated with an opaquer (Sinfony or Ropak) before a denture base polymer bolt was attached (Probase Hot or Lucitone 199). All specimens were heat-polymerized, water saturated (200 days) and thermally cycled (5000 cycles, 5/55 degrees C) before shear bond testing. RESULTS: Silicatized titanium surfaces gave higher bond strength to CGFR polymer (16.2+/-2.34 and 18.6+/-1.32) MPa and cohesive fracture than a sandblasted surface (5.9+/-2.11) MPa where the fracture was adhesive. The opaquer Sinfony gave higher adhesion values and mainly cohesive fractures than the opaquer Ropak. Different surface treatments (roughened or polished) of the CGFR polymer had no effect on bond strength. SIGNIFICANCE: The fracture surfaces of silicatized titanium/CGFR polymer/opaquer layer (Sinfony)/denture base polymers were mainly cohesive. A combination of these materials in an implant-retained supraconstruction is promising for in vivo evaluation.
Morphology of silicon carbide (SiC) fibres from the Norwegian SiC industry has been studied by scanning electron microscopy (SEM). The fibres are an unwanted side-product in SiC production. They represent a probable cause of the observed increased occurrence of lung diseases among SiC workers. The main aim of this work is to give a detailed description of the morphological variation of the fibres. Furthermore, it is important to study the occurrence of various morphological types with respect to job types and process parameters. SiC fibres accounted for >90% of all fibres observed. Eight categories of SiC fibres are described based on their morphology. The most frequent fibre category had a smooth surface and accounted for more than half of the observed SiC fibres. The diameter distributions of the eight fibre types were significantly different except for two of the categories. More than 99% of the SiC fibres observed were
In this work we used non-destructive SEM imaging and EDS analysis to characterize the material composition of an Arabic finger ring, which was found in a 9(th) c. woman's grave at the Viking Age (A.D. 793-1066) trading center of Birka, Sweden. The ring is set with a violet stone inscribed with Arabic Kufic writing, here interpreted as reading "il-la-lah", i.e. "For/to Allah". The stone was previously thought to be an amethyst, but the current results show it to be coloured glass. The ring has been cast in a high-grade silver alloy (94.5/5.5 Ag/Cu) and retains the post-casting marks from the filing done to remove flash and mold lines. Thus, the ring has rarely been worn, and likely passed from the silversmith to the woman buried at Birka with few owners in between. The ring may therefore constitute material evidence for direct interactions between Viking Age Scandinavia and the Islamic world. Being the only ring with an Arabic inscription found at a Scandinavian archaeological site, it is a unique object among Swedish Viking Age material. The technical analysis presented here provides a better understanding of the properties and background of this intriguing piece of jewelry.
Several laboratories have reported that new plasma membrane peptides appear in rodent and human cells after induction of in-vitro resistance to vinca alkaloids, anthracyclines and other anti-neoplastic drugs. Recently, murine monoclonal antibodies have been produced that recognize surface components of such drug-resistant cells. The work presented here describes the development of an in-vivo animal model of this phenomenon using a rat myeloid leukemia. Brown Norway rats were made leukemic with promyelocytes of the BNML line and subsequently were treated with 7.7 mg kg-1 of daunorubicin. After eight cycles of passage-treatment-regrowth, the resulting cells reacted with this antibody in immunofluorescence and cytotoxicity assays. Animals injected with cells that had been pre-incubated with antibody in the absence of complement survived significantly longer than did the controls. Further prolongation of survival occurred when the cells were treated with a second antibody of a different specificity. These results demonstrate that some of the changes associated with in-vitro drug resistance occur also in vivo and potentially may be exploited as a focus for immunotherapy.
In order to identify the cyanobacterial species responsible of anatoxin-a (ATX) production in Lake Garda (Northern Italy), an intensive isolation and culturing of filamentous cyanobacteria were established since 2014 from environmental samples. In this work, we report a detailed account of the strategy adopted, which led to the discovery of a new unexpected producer of ATX, Tychonema bourrellyi. So far, this species is the first documented example of cultured Oscillatoriales able to produce ATX isolated from pelagic freshwater ecosystems. The isolated filaments were identified adopting a polyphasic approach, which included microscopic species identification, genetic characterisation and phylogenetic analyses based on 16S rRNA genes. The taxonomic identification was further confirmed by the high (>99%) rbcLX sequence similarities of the T. bourrellyi strains of Lake Garda with those deposited in DNA sequence databases. More than half of the isolates were shown to produce a significant amount of ATX, with cell quota ranging between 0.1 and 2.6 µg mm(-3), and 0.01 and 0.35 pg cell(-1). The toxic isolates were tested positive for anaC of the anatoxin-a synthetase (ana) gene cluster. These findings were confirmed with the discovery of one ATX producing T. bourrellyi strain isolated in Norway. This strain and a further non-ATX producing Norwegian Tychonema bornetii strain tested positive for the presence of the anaF gene of the ana gene cluster. Conversely, none of the Italian and Norwegian Tychonema strains were positive for microcystins (MCs), which was also confirmed by the absence of mcyE PCR products in all the samples analysed. This work suggests that the only reliable strategy to identify cyanotoxins producers should be based on the isolation of strains and their identification with a polyphasic approach associated to a concurrent metabolomic profiling.
This study aimed to assess radiographically the prevalence and distribution of approximal caries in Danish recruits and to estimate the rate of caries progression during the recruits' late teens. To assess caries progression radiographs taken previously (when leaving the Public Dental Health Care Service, usually at the age of 16-18) were requested. Of 676 recruits previous radiographs (taken 1-7 years earlier) were procured for 640. Approximal surfaces from 7d to 4m in the maxilla and the mandible were assessed for the absence or presence/depth of caries and restorations. Caries progression was expressed by the incidence rate indicating the number of new lesions/number of lesions with progression per 100 years. In the maxilla the average prevalence of enamel and dentine caries was 8.3 and 6.2%, respectively. Overall, 6m had the highest caries experience. In the mandible the average prevalence of enamel and dentine caries was 10.7 and 5.8%, respectively. The highest caries experience was found in 6d. Twenty percent of the recruits had no caries experience in the surfaces under study, 9% had caries experience in 1 surface, 13% in 4-5 surfaces and 25% in more than 10 surfaces. For all surfaces combined, the median incidence rate for the transition from sound to enamel caries was 2.4 surfaces per 100 years, ranging from 0.4 in mandibular 7d to 5.5 in mandibular 6d. The median rate for progression from the enamel to the outer half of the dentine was 9.2 surfaces per 100 years, ranging from 4.4 in mandibular 5m to 18.9 in mandibular 6d. The median incidence rate for progression from the outer to the inner half of the dentine was 2.3 surfaces per 100 years. However, this figure was based on a small number of events and should therefore be interpreted with caution. In conclusion, enamel and dentine caries was found in 9 and 6% of the approximal surfaces in newly called up recruits, and one quarter of the recruits had caries experience in more than 10 approximal surfaces. Generally, the development of new approximal lesions and the progression of enamel caries was a slow process during the late teens.
Observation of 992 motor vehicles and their drivers revealed that most drivers do not have their head restraints effectively positioned. Improper positioning was more common with adjustable restraints, in commercial vehicles, and among male drivers. Some head restraints could not be adjusted properly. Improvements in headrest adjustment might help decrease morbidity in motor vehicle accidents.
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