1,720,966 research outputs found
”one abutment-one time”: optimizing platform-switching concept. 3-year controlled prospective study
No full textBackground:
The “platform-switching” concept showed better peri-implant crestal bone preservation in post-extraction immediately restored implants when compared to matching diameter abutment configuration. However repeated abutment dis/reconnections during restorative procedures from provisional to final crown could produce apical shifting of peri-implant tissues.
Aim:
Aim of this controlled prospective study was to evaluate on bone levels (MBL) the influence of restoration using immediately definitive abutments (one abutment-one time concept) versus provisional abutment later replaced by a definitive abutment.
Materials and methods:
26 patients with 26 hopeless maxillary premolars received a post-extraction wide diameter implant.
Immediately after insertion, 11 patients (Control Group, CG) were immediately restored using a platform-switched provisional titanium abutment. In 15 patients (Test Group, TG), definitive platform-switched titanium abutments were tightened.
In both groups, provisional crowns were adapted, avoiding occlusal contacts.
All implants were definitively restored after 3 months: for the final impression, in CG, traditional impression technique with coping transfer was adopted, dis/reconnecting abutments several times; in TG, metal prefabricated coping was used and final restoration was seated avoiding abutment disconnection.
Digital standardized periapical radiographs using a customized film holder were recorded at baseline (T 0 = implant insertion), final restoration (T1=3 months after), 18 (T2) and 36 months (T3) follow-ups. The MBL was evaluated with a computerized measuring technique applied to radiographs.
Digital subtraction radiography software was used to evaluate radiographic density of bone tissue around implants.
The Student’s t-Test (confidence level: P<0.05) was selected to identify differences between test and control groups at different follow-ups concerning MBL values.
Results:
In the CG peri-implant bone resorption was 0.41mm (SD=0.15mm) at T1, 0.38mm (SD=0.12mm) at T2, 0.53mm (SD = 0.13mm) at T3.
In the TG, on average, peri-implant bone resorption was 0.59 mm (SD=0.19mm) at T1, 0.31mm (SD=0.11mm) at T2, 0.32mm (SD = 0.16mm) at T3.
Statistically significant difference between groups was only found at T3.
At the same follow-up period, higher density in radiographic bone appearance around implant neck was recorded in the TG compared to CG.
Conclusions and clinical implications:
The implant/abutment stability following the minimally invasive prosthetic strategy adopted (“platform-switching” and “one abutment- one time”) could longitudinally produce additional hard tissue preservation compared to implants restored according to “platform-switching” only.
Despite of the encouraging data reported, however, controlled clinical studies on larger patient sample and histologic investigations are required to confirm this hypothesis, analyzing biologic mechanism
Guided bone regeneration and edentulous ridge expansion in localized alveolar ridge defects: A retrospective evaluation.
No full textDental implant sites in healthy versus diabetic subjects: A two-year clinical and bacteriological assessment
No full textThe aim of this study was to analyze by Real-Time Polymerase Chain Reaction (PCR) possible differences in periimplant microbiota of patients without significant systemic diseases versus patients affected by non-insulin-dependent diabetes mellitus (NIDDM), both treated with dental implants with the same implant-abutment system. Patients suffering from NIDDM, and those with no history of major systemic diseases, treated with dental implants at the Prosthodontics Operative Unit of "Sapienza" University of Rome in the period February 2009 - March 2010 were considered. Clinical parameters as well as microbiological profile were evaluated for each implant site at 3, 6, 12, and 24 month follow-up. Crevicular fluid was collected for microbial sampling and analyzed by Real-Time PCR in order to identify the possible presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum and Prevotella intermedia. Eight patients suffering from NIDDM and 22 with no history of major systemic diseases were included in the present investigation, each having received one to three dental implants. All the implants had been loaded 3 months after surgery, and the average follow-up after implant placement was 26.37±3.86. Clinical parameters showed no noticeable difference between the two groups, except for the Implant Stability Quotient (ISQ) that showed significantly lower values in NIDDM patients. A slightly higher amount of the considered pathogenic bacteria were retrieved in samples collected from patients with NIDDM (7.38x105) in comparison with those of healthy subjects (6.78x105), though the differences were below statistical significance. Within the limitations of the present study, a slight correlation was empirically detected between gene expression profiles of microbial populations and history of NIDDM, which however remained below the statistical significance. Further well-designed clinical studies may be useful to conclusively clarify the impact of subgingival microflora on the increased susceptibility of diabetic patients to periimplantitis
Dental implant sites in healthy versus diabetic subjects: A two-year clinical and bacteriological assessment
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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