1,051 research outputs found
Logistic regression: Part 2
No full textIn the previous article (Pandis N. Logistic regression: Part 1. Am J Orthod Dentofacial Orthop 2017;151:824-5), I introduced logistic regression and showed how it can be used as an alternative to the chi-square test. Logistic regression becomes more interesting when we include more variables. I will continue with the example as shown in Table I
Semantically annotated hypermedia services
No full textHypermedia systems’ researchers investigate the various approaches in the way documents and resources are linked, navigated and stored in a distributed environment. Unfortunately, those systems fail to provide effortlessly usable discrete services, since it is difficult both to discover and to invoke any of them. This paper proposes the usage of emerging technologies that try to augment the Web resources with semantics in order to provide Hypermedia services that can be easily discovered, and integrated by potential third party developers. In this context, we analyze the benefits for the Hypermedia community upon the adoption of Semantic Web technologies for the description of Hypermedia services, and we implement an initial corresponding ontology
Biomechanics of Self-Ligation: Analysis of Forces and Moments Exerted by Self-ligating Brackets
No full text
Salivary Levels of Cariogenic Bacteria in Patients Treated with Self-Ligating and Conventional Brackets
No full textAuthor self-citation in orthodontics is associated with author origin and gender.
No full textBACKGROUND
The aims of this bibliometric study were to determine author self-citation trends in high-impact orthodontic literature and to investigate possible association between self-citation and publication characteristics.
METHODS
Six orthodontic journals with the highest impact factor as ranked by 2017 Journal Citation Reports were screened for a full publication year (2018) for original research articles, reviews, and case reports. Eligible articles were scrutinized for article and author characteristics and citation metrics. Univariable and multivariable negative binomial regression was used to examine associations between self-citation incidence and publication characteristics.
RESULTS
Medians for author self-citation rate of the most self-citing authors and self-citations were 3.03% (range 0-50) and 1 (range 0-19), respectively. In the univariable analysis, there was no association between self-citation counts and study type (P = 0.41), article topic (P = 0.61), number of authors (P = 0.62), and rank of authors (P = 0.56). Author origin (P = 0.001), gender (P = 0.001) and journal (P = 0.05) were associated with self-citation counts and in the multivariable analysis only origin and gender remained strong self-citation predictors. Asian authors and females self-cited significantly less often than all other regions and male authors.
CONCLUSIONS
Authors in orthodontics do not self-cite at a frequency that suggests potential citation manipulation. Author origin and gender were the only variables associated with citations counts. More bibliometric research is necessary to draw solid conclusions about author self-citation trends in orthodontic literature
Most recommended medical interventions reach P<0.005 for their primary outcomes in meta-analyses
No full textBackground: It has been proposed that the threshold of statistical significance should shift from P-value < 0.05 to P-value < 0.005, but there is concern that this move may dismiss effective, useful interventions. We aimed to assess how often medical interventions are recommended although their evidence in meta-analyses of randomized trials lies between P-value = 0.05 and P-value = 0.005.
Methods: We included Cochrane systematic reviews (SRs) published from 1 January 2013 to 30 June 2014 that had at least one meta-analysis with GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessment and at least one primary outcome having favourable results for efficacy at P-value < 0.05. Only comparisons of randomized trials between active versus no treatment/placebo were included. We then assessed the respective UpToDate recommendations for clinical practice from 22 May 2018 to 5 October 2018 and recorded how many treatments were recommended and what were the P-values in their meta-analysis evidence. The primary analysis was based on the first-listed outcomes.
Results: Of 608 screened SRs with GRADE assessment, 113 SRs were eligible, including 143 comparisons of which 128 comparisons had first-listed primary outcomes with UpToDate coverage. Altogether, 60% (58/97) of interventions with P-values < 0.005 for their evidence were recommended versus 32% (10/31) of those with P-value 0.005-0.05. Therefore, most (58/68, 85.2%) of the recommended interventions had P-values < 0.005 for the first-listed primary outcome. Of the 10 exceptions, 4 had other primary outcomes with P-values < 0.005 and another 4 had additional extensive evidence for similar indications that would allow extrapolation for practice recommendations.
Conclusions: Few interventions are recommended without their evidence from meta-analyses of randomized trials reaching P-value < 0.005.
Keywords: P-value; Cochrane; UpToDate; meta-analysis; recommendation; statistical threshold
In vivo regeneration of microvascular pedicle
No full textObjective: The difficulty of obtaining significant long-term
patency and good wall mechanical strength in vivo has been
a significant obstacle in achieving small-diameter vascular
prostheses. The aim of the present study was to develop
a prosthetic graft that could perform as a small diameter
vascular conduit for artery and vein regeneration.
Methods: 60 Male Wistar rats weighing 250-350g were used.
Tubular structures of hyaluronan (HYAFF-11 tubules, 2 mm
diameter, 1 cm length) were grafted in the abdominal aorta
(n = 30), and in the vena cava (n = 30) of rats as temporary
absorbable guides to promote regeneration of vascular
structures. No anticoagulants were used either before or after
the operation. Performance was assessed at 5, 15, 30, 60, 120,
and 180 days after surgery by histology (haematoxylin-eosin
and Weighert solution), immunohistochemistry (antibodies
to von Willebrand factor, CD34, vascular endothelial growth
factor receptor-2 and to Myosin Light Chain Kinase), and
ultra-structural analysis.
Results: These experiments resulted in three novel findings:
1) complete endothelialisation of the tube’s luminal surface
occurred; 2) sequential regeneration of vascular components
led to complete vascular wall regeneration 15 days after
surgery; and 3) the biomaterial used created the ideal
environment for the delicate regeneration process during
the critical initial phases, yet its biodegradability allowed
for complete degradation of the construct four months after
implantation, at which time, a new artery and a new vein
remained to connect the vascular stumps. This study assesses
the feasibility to create a completely biodegradable vascular
regeneration guide in vivo, able to sequentially orchestrate
vascular regeneration events needed for very small artery and
vein reconstruction.
Conclusion: HYAFF-11 prosthesis opens new innovative
possibilities of surgical treatment in the field of reconstructive
microsurgery and paediatric vascular surgery, and a novel
experimental model to study artery and vein in vivo
regeneration processes
- …
