1,720,963 research outputs found
Malattia parodontale e trauma da occlusione: una controversia ancora aperta?[Periodontal disease and occlusal trauma: a still debated controversy? A review of the literature].
No full textAbstract
In the "Glossary of Periodontics Terms" written by the American Academy of Periodontology, the occlusal trauma is defined as "an injury to the attachment apparatus as a result of excessive occlusal forces". Nowadays, the effects of occlusal trauma on tooth support tissues, the onset and the progression of periodontal disease are still debated: many commonplaces have been disproved, but some doubts and not yet clear points remain, even owing to the difficult diagnosis of the presence and the real clinical impact of a traumatic occlusion. Then, ethical reasons prevent researchers from prospective clinical trials. At the beginning of the last century occlusal trauma has been supposed to be an etiologic factor of "alveolar pyorrhea", but several studies attending more strict scientific criteria failed to prove such correlation. On the basis of the bacterial genesis of periodontal disease, researchers started evaluating the possible effects of occlusal discrepancies on incidence, progression and treatment outcomes of periodontitis, but all the results underlined the more relevant role played by micro-organisms. The present review of the literature runs through this controversy again, analysing the most significant studies published
I biofilm del cavo orale. Formazione, sviluppo e implicazioni nell'insorgenza delle malattie correlate all'accumulo di placca batterica. [Biofilms of the oral cavity. Formation, development and involvement in the onset of diseases related to bacterial plaque increase]
No full textBiofilm is defined as a community of bacteria intimately associated with each other and included within an exopolymer matrix: this biological unit exhibits its own properties, quite different in comparison with those showed by the single species in planktonic form. The oral cavity appears as an open ecosystem, with a dynamic balance between the entrance of microrganisms, colonisation modalities and host defences aimed to their removal: to avoid elimination, bacteria need to adhere to either hard dental surfaces or epithelial surfaces. The oral biofilm formation and development, and the inside selection of specific microrganisms have been correlated with the most common oral pathologies, such as dental caries, periodontal disease and peri-implantitis. Many of these bacteria are usual saprophytes of the oral environment, that, in particular situations, can overcome and express their virulence factors: to better understand the mechanisms of these pathologies it's necessary to know the complex interactions between all the bacterial species inside the biofilm and host tissues and responses. The present paper is a review of the most significant studies on the biofilm development modalities, their correlations with either health or illness of the oral cavity, the bacterial co-aggregation strategies and the biofilm response to antimicrobial agents
Oral microbial biofilms and plaque-related diseases: microbial communities and their role in the shift from oral health to disease
No full textAbstract: many oral pathologies, such as dental caries, periodontal disease and peri-implantitis are plaque-related. Dental plaque is a microbial biofilm formed by organisms tightly bound to a solid substrate and each other by means of an exopolymer matrix. Bacteria exhibit difefrent properties when contained within a biofilm. Knowing the mechanism controlling the formation and deveopment of biofilms can help to understand the emergence and progression of such pathologies and to plan effective treatment. Most periodontal pathogens are common saprophytes of the oral cavity, expressing their virulence only in a sisceptible host or when some changes comw about in the oral envirnment. Physical, metabolic and physiological interactions may cause positive or negative effects among the various microbiota present.Such mechanisms of antagonisms/synergy select the bacterial population and alterations of its composition affect the balance with the host and may lead to pathology. The efefctivenes of antimicrobial agents, as measured trough in vitro tests, is dramatically reduced in vivo due to the properties of the microbial community: mature, intact biofilms are les sensitive to such agents, as the exopolymer matrix, bacterial enzymes and slow growth rate hinder the action of chemotherapeutic agents. The present literature review aims to examine the most representative sudies, focusing on the characteristics of the bacterial communities and the crucial shift from the oral health to plaque-related diseases.
Keywords: Microbial film - Dental plaque - Periodontal disease - Peri-implantitis - Bacterial virulence - Host susceptibilit
Grave malocclusione di III Classe con deficit di crescita dentoalveolare conseguente all'anchilosi di un deciduo. Caso clinico
No full textBucco-lingual crestal bone changes after immediate and delayed implant placement
No full textBackground: Implants placed immediately after tooth extraction offer several advantages, but many authors have reported problems in filling the residual gap between the implant and the socket walls. Barrier and grafting techniques have been tested and yield varying results, so it has been suggested that the timing of implant placement may be important for success. The aim of thi study was to analyze bone healing and coronal bone remodeling around 35 implants, 20 placed immediately after tooth removal and 15 placed 6 to 8 weeks after extraction. Methods: All the implants were submerged and placed within the alveoli confines, leaving circumferential defects because the implants did not contact the bone at their coronal aspects; stabilization was achieved in the bone apically. After implant placement the mean distance from buccal bone to lingual bone was 10 mm (SD 1.522) for immediate implants and 8.86 mm (SD 2,356) for delayed implants. No membrane or filling materials were used. Primary flap closure was accomplished in all cases. Results: At second stage surgery all peri-implant defects were filled, and the mean distance from buccal bone to lingual bone was 8.1 mm (SD 1.334) for immediate implants and 5.8 mm (SD 1.265) for delayed implants. This pattern of coronal bone remodeling, showing a narrowing of the bucco-lingual width, was clinically similar for the two groups, although it should be noted that the delayed implants exhibited smaller buccolingual bone width already at the first measurement: it can be speculated that early remodeling may start immediately after tooth extraction and continue, non-uniformly, even after delayed implant placement. Conclusions: This study suggests that circumferential defects could heal clinically without any guided bone regeneration (GBR) in both experimental groups and that the procedure was virtually free from complications in the postoperative period, probably because of the absence of barrier membranes and /or grafting materials. Histologically, peri-implant defects of over 1.5 mm heal by connective tissue apposition, rather than by direct bone-to-implant contact but clinically this healing may be very successfu. No histological analysis was carried out in the present study, but even the largest residual gaps were filled with hard tissue that could not be probed. Thus such outcomes can be considered clinically successful. The different rate of bone remodeling around immediate or delayed implants could have implications fort he preferred timing of implant placement in sites of high esthetic concern.
Key words:Bone regeneration; bone remodeling; dental implants, immediate; peri-implants; wound healing
Bucco-lingual crestal bone changes after immediate and delayed implant placement
No full textBACKGROUND:
Implants placed immediately after tooth extraction offer several advantages, but many authors have reported problems in filling the residual gap between the implant and the socket walls. Barrier and grafting techniques have been tested and yield varying results, so it has been suggested that the timing of implant placement may be important for success. The aim of this study was to analyze bone healing and coronal bone remodeling around 35 implants, 20 placed immediately after tooth removal and 15 placed 6 to 8 weeks after extraction.
METHODS:
All the implants were submerged and placed within the alveoli confines, leaving circumferential defects because the implants did not contact the bone at their coronal aspects; stabilization was achieved in the bone apically. After implant placement the mean distance from buccal bone to lingual bone was 10 mm (SD 1.522) for immediate implants and 8.86 mm (SD 2.356) for delayed implants. No membrane or filling materials were used. Primary flap closure was accomplished in all cases.
RESULTS:
At second-stage surgery all peri-implant defects were filled, and the mean distance from buccal bone to lingual bone was 8.1 mm (SD 1.334) for immediate implants and 5.8 mm (SD 1.265) for delayed implants. This pattern of coronal bone remodeling, showing a narrowing of the bucco-lingual width, was clinically similar for the two groups, although it should be noted that the delayed implants exhibited smaller bucco-lingual bone width already at the first measurement: it can be speculated that early remodeling may start immediately after tooth extraction and continue, non-uniformly, even after delayed implant placement.
CONCLUSIONS:
This study suggests that circumferential defects could heal clinically without any guided bone regeneration (GBR) in both experimental groups, and that the procedure was virtually free from complications in the postoperative period, probably because of the absence of barrier membranes and/or grafting materials. Histologically, peri-implant defects of over 1.5 mm heal by connective tissue apposition, rather than by direct bone-to-implant contact, but clinically this healing may be very successful. No histological analysis was carried out in the present study, but even the largest residual gaps were filled with hard tissue that could not be probed. Thus, such outcomes can be considered clinically successful. The different rate of bone remodeling around immediate or delayed implants could have implications for the preferred timing of implant placement in sites of high esthetic concern
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Scanning Electron Microscopy Fractography Analysis of Fractured Hollow Implants
No full textAbstract
Fracture of the implant is one of the possible complications affecting dental implants; it is a
rare event but of great clinical relevance. The aim of the present study was to perform a
scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral
Implantology (ITI) hollow implants removed because of fracture. The most common clinical
risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent.
Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with
the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures
could be due to an association of multiple factors such as fatigue, inner defects, material
electrochemical problems, and tensocorrosion.
Key Words: fractography, implant fracture, titanium implant
Variations on the Author
Get PDF“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
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