Influence of Different Factors on the Resonance Frequency Analysis in Assessment of Implant Stability - Review

IntroductionImplant stability is one of the key factors in regard to the successful outcome of implant treatment. Resonance frequency analysis (RFA) is one of the most commonly used methods in measuring the implant primary and secondary stability. The method is reliable and noninvasive, which makes it suitable at the different stages of the implant treatment.AimThe aim of this review was to establish some of the factors, which could affect the results obtained during RFA.Materials and MethodsArticles related to the subject were searched in PubMed and Google Scholar databases. Articles only in English language, published from 1996 to 2019, were included. Variety of keywords in different combinations were used to conduct the search.ResultsArticles, included in this review described clinical and experimental studies. Few reviews of the literature were added as well. Some of the articles considered RFA as a single method for measuring implant stability, while others described its use in combination with other methods. Bone-related factors, implant surface, diameter, length, as well as the position of the transducer of the device were discussed as factors, which could influence the ISQ values.ConclusionIt seems that among the discussed factors, BIC, bone density, implant diameter and the orientation of the transducer demonstrated more distinct relation to the RFA results. The influence of the implant surface modification and implant length on the ISQ values remains controversial

Factors Affecting Bone Temperature Increase During Implant Surgery - Review

IntroductionDuring implant surgery certain amount of heat is produced. It is known that temperature increase above the critical threshold of 47°C for a minute could lead to thermal osteonecrosis, which could be the reason for an early implant failure.AimThe aim of this review was to reveal the multifactorial nature of bone temperature rise during dental implant surgery.Materials and MethodsPubMed and Google Scholar databases were searched to select articles related to the topic. The review includes articles published from 1972 to 2019, only in English language. ResultsAll reviewed original articles, describing studies, whose aim was to observe the heat generation during implant surgery, are experimental. A few reviews were included. As potential risk factors for thermal damage of the bone were considered the site preparation protocol, drill wear, drill design, drilling speed and cooling effectiveness.ConclusionHeat generation during implant site preparation could be increased by performing guided implant or piezoelectric surgery. The use of combined irrigation at higher speeds, sharper drills and laser-assisted osteotomy could help avoid the risk of thermal damage to the bone. The heat production during the implant site preparation is a subject to many studies, but there is still a lack of data about the temperature rise during implant insertion

Adjunctive antibiotic therapy in cases of periodontitis and peri-implantitis

IntroductionPeriodontitis and peri-implantitis are plaque-induced diseases, which are associated with certain bacteria. The conventional treatment aims primarily at tooth or implant surface debridement. In certain cases, surgical therapy is necessary. To improve the outcome of the treatment, systemic or topical antibiotics could be considered.AimThe aim of this review is to investigate the effect of the adjunctive systemically or topically delivered antibiotics on the outcome of the periodontitis and peri-implantitis treatment.Materials and MethodsArticles related to the topic were searched in the PubMed database. Articles published from 2000 to 2019, only in English language, were included in the review. The search was conducted with a variety of keywords in different combinations being used. These were: “periodontitis”, “peri-implantitis”, “antibiotic”, “local”, “metronidazole”, “amoxicillin”, “azithromycin”, “tetracycline”.ResultsForty-seven articles were included in the review. The selected articles described the adjunctive systemic and/or local delivery of metronidazole, azithromycin, the combination of metronidazole and amoxicillin and some representatives of the tetracycline group, such as doxycycline and minocycline in cases of periodontitis and peri-implantitis.ConclusionThe adjunctive systemic and topical antibiotic therapy could benefit the outcome of periodontitis and peri-implantitis treatment

Comparison between the influence of implant diameter and implant length on the primary stability

INTRODUCTIONThe primary stability is a factor for successful osseointegration of dental implants. It is believed that factors that can increase the contact area between the implant and the bone, such as the implant shape, length, and diameter, can also increase the primary stability.AIM   The aim of this study was to determine whether the increase of implant length or the increase of implant diameter would contribute more to the enhancement of primary stability.MATERIALS AND METHODSThe implant primary stability of 60 implants distributed in 6 groups, according their diameter, length and surface topography was evaluated using three methods: assessment of mean insertion torque, periotest values, and resonance frequency analysis.RESULTS AND DISCUSSIONThe results demonstrated that the primary stability achieved by increasing the diameter of the implants by 0.7 mm was comparable to that obtained by increasing their length by 2 mm at a smaller diameter (4.1 mm). When the difference in the diameter increased more (from 0.7 mm to 1.5 mm, when comparing the 3.3 mm/10 mm and 4.8 mm/8 mm implants), the increase of the length of the smaller diameter implants did not result in primary stability values comparable to those obtained during the insertion of  wider and shorter implants.CONCLUSIONConsidering our results as well as the literature data, we can conclude that the increase of the implant diameter affects more the improving of the primary stability than the increase of the implant length. However, it should be taken into account that this refers to a specific diameter change of 1.5 mm and length change of 2 mm. More studies, including implants with a greater difference in the length and a different diameter to length ratio, are needed to confirm or reject this relation

REGULATION OF ABCG5 AND ABCG8 STEROL TRANSPORTERS IN BILIARY CHOLESTEROL ELIMINATION, REVERSE CHOLESTEROL TRANSPORT AND DYSLIPIDEMIA

ATP-binding cassette transporters ABCA1 and ABCG1 initiate reverse cholesterol transport generating HDL particles, whereas ABCG5/G8 promote biliary cholesterol secretion thereby facilitating the last step of reverse cholesterol transport. Mutations in the leptin axis result in obesity and dyslipidemia in ob/ob and db/db mice. These mice have defective HDL clearance, increased plasma cholesterol and decreased biliary cholesterol elimination. My studies demonstrate that ABCG5/G8 protein is low in these animals and can be restored with caloric restriction or leptin replacement. To directly test whether ABCG5/G8 alone is able to correct reverse cholesterol transport defect, liver specific ABCG5/G8 expression was achieved in db/db mice by administration of adenoviral ABCG5 and ABCG8. Restoration of biliary cholesterol is able partially to correct dyslipidemia in obese mice, but only in the presence of ezetimibe, an inhibitor of cholesterol absorption. ABCG5/G8 is the body’s primary defense against toxic effects of plant sterols. Plant sterols are used as cholesterol lowering food supplements. However, increased plasma plant sterol concentrations are associated with vascular lesions in dyslipidemic patients and animals. My in vitro studies demonstrate that individual plant sterol alter ABCA1 and ABCG1 abundance, cholesterol efflux and inflammatory cytokine secretion in macrophage foam cells at levels found in humans that consume plant sterol supplements

Bone block augmentation - a long-term follow-up

IntroductionAutogenous bone block grafting is used for both vertical and horizontal augmentation of the upper and lower jaw. The bone block could be provided using extraoral or intraoral donor location.AimThe aim of this study was to observe the survival rate, the marginal bone level and the bleeding on probing (BOP) for a period of 4 to 6 years of implants, inserted in autogenous bone block graft.Materials and MethodsWe considered advanced horizontal bone loss, where guided bone regeneration with simultaneous implant placement could not be performed and/or vertical bone loss, where vertical augmentation of the alveolar  bone of more than 3 to 6 mm is required,  as indications for the bone block grafting procedure. As an intraoral donor site was used the mental area.Results and Discussion The mean observation period was 4.81 years. The mean marginal bone loss was 0.442 mm, as bone resorption was established in 48% of all cases, BOP was observed in 17.7 % of the cases. No correlation was found between BOP and bone loss. The survival rate of the implants placed into bone augmented using autogenous bone block graft was 98.7 %.ConclusionFor an implant placement we considered a period of 4 months after the procedure enough to provide high survival rate of the implants. The implants placed in bone augmented using autogenous bone block grafting according to our methodology demonstrated high survival rate and unstable marginal bone level

Determination of the Bacterial Community in Soils Associated with Rare Wild Leguminous Species Cicer Montbretii Jaub. amp%253B Spach and Lupinus albus L. in Strandzha Natural Park

The soil formation in Strandzha Mountain is influenced by the particular combination of the climate%252339%253Bs unique forest tree vegetation, the extraordinary variety of root and soil-forming rocks, the hilly low-mountainous relief with significant fragmentation, a densely located hydrographic network with short slopes and dominant exposures. The diversity of soil microorganisms is crucial for plant growth and development and it makes it possible to understand in detail the plant-microbial interactions. The objectives of this study were to determine soil bacteria associated with rare wild leguminous species Cicer montbretii Jaub. amp%253B Spach (Constantinople chickpeas) and Lupinus albus L. (white lupinus) in Strandzha National Park. A new locality of Cicer montbretii Jaub was marked nearby village of Brodilovo. L. albus was found in saline-alkaline soil (A1) and yellow earth podzolic soils (A2) around the village of Brodilovo and the Great Pazvlak area. C. montbretii was found to grow on cinnamon forest soils (B1) and siliceous red soil (B2). A study was conducted by physio-chemical analyses and by assessing 16S rDNA metagenomics technique used to generate a total of 126,837 reads from the samples. The most significant number of observed species 2249 was found in soils saline-alkaline soil (B1) soil. According to that result, the higher diversity indices were calculated in the also in B1 soil. The alpha%253B-diversity analysis reported yielded similar Shannon indices ranging from 8,322 in B2 to 9,337 in B1. The analyses revealed that B2 yellow earth podzolic soil, unique for Strandzha, has the largest composition with Proteobacteria 44%25 and the lowest in Actinobacteria 20%25. Opposite, in A1 saline-alkaline soil have the richest composition of Actinobacteria 52%25 and the poorest in Proteobacteria 23%25. C. montbretii was found in neutral A2 and B2 soils, while L. ablus prefer acidic A1 and B1 soils. The determination of the microbiological status of the soils associated with Constantinople chickpeas and white lupinus and the annual monitoring of the species in Strandzha Park will determine the methods for the most effective maintenance and storage outside their habitats

Evaluation of cross-layer reliability mechanisms for satellite digital multimedia broadcast

This paper presents a study of some reliability mechanisms which may be put at work in the context of Satellite Digital Multimedia Broadcasting (SDMB) to mobile devices such as handheld phones. These mechanisms include error correcting codes, interleaving at the physical layer, erasure codes at intermediate layers and error concealment on the video decoder. The evaluation is made on a realistic satellite channel and takes into account practical constraints such as the maximum zapping time and the user mobility at several speeds. The evaluation is done by simulating different scenarii with complete protocol stacks. The simulations indicate that, under the assumptions taken here, the scenario using highly compressed video protected by erasure codes at intermediate layers seems to be the best solution on this kind of channel

Application d'un réseau de neurones ARTMAP à la reconnaissance des commandes gestuelles d'édition de documents braille

Applications crayon -- La tâche d'édition -- Commandes gestuelles -- Reconnaissance de commandes gestuelles -- Cadre fonctionnel de l'éditeur -- Analyse des besoins de l'édition gestuelle -- Plate-forme pour le développement d'applications à crayon et types d'applications à crayon -- La portée des reconnaisseurs -- Solution du problème de cohabitation entre le reconnaisseur local et le reconnaisseur du système -- Détails sur l'implantation de l'éditeur gestuel -- Le choix des gestes -- Revue des commandes gestuelles proposé.es par des chercheurs et des compagnies -- Sélection d'un ensemble de commandes gestuelles -- Le réseau ARTMAP pour la reconnaissance des commandes gestuelles -- Propriétés intéressantes des machines neuronales pour la reconnaissance des commandes gestuelles -- Le réseau ARTI -- Nature des données et prétraitement -- L'architecture ARTMAP -- la base de notre reconnaisseur de commandes gestuelles -- L'éditeur gestuel adaptable -- Les paramètres du reconnaisseur gestuel -- La création de la base de données