Nutrient mineralization patterns in shelf waters of the Western Iberian upwelling

24 páginas, 10 figuras, 2 tablasA set of hydrographicdata collectedduring severalcruisesto theNWIberian upwelling systemhas been used to assess the patterns of nutrient mineralizationover the shelf. Mineralized nutrient ratios (N/P and N/Si)in the lowerwatercohrmnare clearlybelowthe ratios characteristicof freshly upwelled oceanic waters. Nitrogen mineralization, in comparison to phosphorus mineralization, is incomplete,in agreementwith phosphate’sfaster regenerationrate and the low residence time of water, which precludes complete mineralization. Silicate shows the highest enrichmentas a consequenceof the selectiveconcentrationof particulate biogenicsilica in the near bottom waters. Diffusionof nutrients mineralizedin the sedimentsseemsto representan important contribution.TheIowestmineralizationof the surveyedarea is foundto the north of CapeFinisterre, especiallywith regard to silicate.To the South, the Rias Baixas(four large embayments)return as reducingparticulate organicmatter (POM)a smallfraction of the upwellednutrientsimportedfrom the shelf. However,the out-flowingfreshwatercontributesto stratificationof coastal waters, which favoursPOMproduction,accumulationand sedimentation.In addition,highlevelsofnewdissolved organic matter (DOM) in the outflowcan also enhanceprimary productionin shelfsurface waters. Finally, highest mineralization was found to the south of the River Miiio, where there are no embayments and the shelf is wider. Mineralization tends to: (1) increase the potential primary productionof thisecosystembyupto 50%,(nitrogenIimitation)orup to 80%(siliconlimitation);(2) favour the developmentof phytoplanktonassemblagesdominatedbydiatoms(Sienrichmentdouble that ofN and P); and (3)bufferthe largespatial and temporaldifferencesintroducedbythe advected nutrientsSupport for this work came from EU projects contract No. MAST-CT90-0017and MAS2- CT93-006Peer reviewe

Collagen-based fibrillar multilayer films cross-linked by a natural agent.

Surface functionalization plays an important role in the design of biomedical implants, especially when layer forming cells, such as endothelial or epithelial cells, are needed. In this study, we define a novel nanoscale surface coating composed of collagen/alginate polyelectrolyte multilayers and cross-linked for stability with genipin. This buildup follows an exponential growth regime versus the number of deposition cycles with a distinct nanofibrillar structure that is not damaged by the cross-linking step. Stability and cell compatibility of the cross-linked coatings were studied with human umbilical vein endothelial cells. The surface coating can be covered by a monolayer of vascular endothelial cells within 5 days. Genipin cross-linking renders the surface more suitable for cell attachment and proliferation compared to glutaraldehyde (more conventional cross-linker) cross-linked surfaces, where cell clumps in dispersed areas were observed. In summary, it is possible with the defined system to build fibrillar structures with a nanoscale control of film thickness, which would be useful for in vivo applications such as inner lining of lumens for vascular and tracheal implants.journal articleresearch support, non-u.s. gov't2012 Jul 092012 06 13importe

Modification of macroporous titanium tracheal implants with biodegradable structures: tracking in vivo integration for determination of optimal in situ epithelialization conditions.

Previously, we showed that macroporous titanium implants, colonized in vivo together with an epithelial graft, are viable options for tracheal replacement in sheep. To decrease the number of operating steps, biomaterial-based replacements for epithelial graft and intramuscular implantation were developed in the present study. Hybrid microporous PLLA/titanium tracheal implants were designed to decrease initial stenosis and provide a surface for epithelialization. They have been implanted in New Zealand white rabbits as tracheal substitutes and compared to intramuscular implantation samples. Moreover, a basement membrane like coating of the implant surface was also designed by Layer-by-Layer (LbL) method with collagen and alginate. The results showed that the commencement of stenosis can be prevented by the microporous PLLA. For determination of the optimum time point of epithelialization after implantation, HPLC analysis of blood samples, C-reactive protein (CRP), and Chromogranin A (CGA) analyses and histology were carried out. Following 3 weeks the implant would be ready for epithelialization with respect to the amount of tissue integration. Calcein-AM labeled epithelial cell seeding showed that after 3 weeks implant surfaces were suitable for their attachment. CRP readings were steady after an initial rise in the first week. Cross-linked collagen/alginate structures show nanofibrillarity and they form uniform films over the implant surfaces without damaging the microporosity of the PLLA body. Human respiratory epithelial cells proliferated and migrated on these surfaces which provided a better alternative to PLLA film surface. In conclusion, collagen/alginate LbL coated hybrid PLLA/titanium implants are viable options for tracheal replacement, together with in situ epithelialization.journal articleresearch support, non-u.s. gov't2012 Aug2012 03 02importe

Les ciments de scellement orthodontiques

Quatre types de ciments de scellement orthodontiques sont étudiés. Le rôle des principaux constituants de chacun d'eux, les caractéristiques de mise en œuvre et les propriétés finales sont exposés. Les qualités et les performances cliniques sont également évoquées. Il s'avère ainsi que, parmi les ciments actuellement commercialisés, les verres ionomères de la dernière génération donnent globalement les meilleurs résultats en raison de la facilité de mise en œuvre, la libération de fluor, l'adhésion à l'émail, une faible solubilité en bouche et une réduction de la fréquence des descellements

Unusual Maxillary First Molars with C-Shaped Morphology on the Same Patient: Variation in Root Canal Anatomy

A maxillary first molar should be considered a four-canal tooth until proved otherwise; however, a clinician should also be aware of the possibility of the presence of C-shaped root canal configuration with or without possibility of splitting into two or three canals. The two clinical cases reported in this paper describe the endodontic treatment of two maxillary first molars, on the same patient, with uncommon anatomy: the first case is about a maxillary first molar with only one C-shaped root and one oval canal with a large buccolingual diameter, a C1 type according to Fan's classification; the second case, about the contralateral maxillary first molar, is probably the first case documented of a maxillary first molar with a C-shaped root canal and C-shaped root with complete fusion of the three roots, having a C3 configuration

Improved single visit management of old infected iatrogenic root perforations using Biodentine®

Aim: The aim of this retrospective observational case series study was to evaluate the middle term outcomes on endodontic management of old infected iatrogenic root perforations using Biodentine. The treatments were always concluded in a single visit, without previous medication with calcium hydroxide. Our goal was to facilitate this kind of treatments and to make them more reproducible and manageable even for a general practitioner or a student. Methodology and methods: Between January 2011 and June 2016, 51 patients with old infected root perforations have been enrolled. All the treatments were performed using Biodentine in a single visit. Infected root perforation repair was performed by supervised dental students (39%) or a qualified endodontist (61%), employing surgical microscope magnification during treatments. After the treatment, the 51 patients were monitored for 18–64 months. We used clinical and radiographic examinations. Results: Of 51 examined teeth, 48 (94%) were classified as healed. The time, the size and the location of the perforations did not have a significant effect on the outcome. We proved the ineffectiveness of the null hypothesis. According to this latter, the single visit treatment of old infected perforations with Biodentine was inadequate. Conclusions: In single visit treatments, Biodentine seems to provide a biocompatible and effective seal in acidic environment, in accidental root perforations, even if the treatment is performed by an inexperienced operator and regardless of the location, the size and the time of occurrence of the perforation. Riassunto: Obiettivi: Lo scopo di questo studio osservazionale retrospettivo è stato quello di valutare la percentuale di guarigione a medio termine nel trattamento delle “old infected” perforazioni con contaminazione batterica usando biodentine. Il trattamento di tutte le perforazioni è stato fatto in seduta singola, senza medicazione con idrossido di calcio. Altro obiettivo è stato quello di facilitare questo tipo di trattamenti, rendendoli riproducibili e fattibili anche per un dentista generico o uno studente. Materiali e metodi: Tra Gennaio 2011 e Giugno 2016, abbiamo selezionato 51 pazienti con “old infected” perforationi. Ogni caso é stato trattato con Biodentine in singola seduta. Il 39% dei casi é stato trattato da studenti della clinica universitaria sotto la supervisione di un tutor senior, mentre il 61% da un endodontista qualificato, usando il microscopio operatorio durante ogni fase del trattamento. Dopo il trattamento, i 51 pazienti sono stati monitorati tra 18 e 64 mesi, con esami radiografici e clinici. Risultati: Fra i 51 denti esaminati, 48 (94%) sono stati classificati come guariti. Nel nostro studio il tempo, la dimensione e la localizzazione della perforazione non hanno avuto alcun valore prognostico. Abbiamo dunque rigettato l’ipotesi nulla, secondo la quale il trattamento in singola visita delle “old infected” perforazioni con Biodentine fosse inadequato. Conclusioni: Il trattamento delle “old infected” perforazioni in ambiente acido in singola visita con Biodentine sembra assicurare un sigillo biocompatibile e tridimensionale della perforazione anche se il trattamento è stato eseguito da operatori senza tanta esperienza (studenti), indipendentemente dalla localizzazione, dimensione e tempo dell’avvenuta perforazione. Keywords: Iatrogenic perforation, Acidic environnement, Bioactivity, Biodentine, Single visit, Parole chiave: Perforazione iatrogena, Ambiente acido, Bioattività, Biodentine, Singola visit

Microscopic and Chemical Assessments of the Filling Ability in Oval-Shaped Root Canals Using Two Different Carrier-Based Filling Techniques

Objectives: The aim of this study was to assess the filling ability in oval-shaped canals using two different carrier-based filling techniques. Materials and methods: Twenty-four human mandibular premolars with one oval canal were selected. Canals were shaped using WaveOne Gold Primary and ProGlider. Samples were divided into two groups and filled as follows: Thermafil and GuttaCore. The proportions of gutta-percha-filled areas (GPFAs), sealer-filled areas (SFAs), and void areas (VA), at 2 and 5 mm, were analyzed using optical numeric microscope, scanning electron microscope, and energy-dispersive X-ray. Statistical analysis: Data were compared by Kruskal-Wallis one-way analysis of variance on ranks, with statistical significance set at α = 0.05. Results: At 2 and 5 mm distances from the apex, this study discloses no statistically different filling ability for the two techniques. Concerning each sample treated using both filling systems, the presence of tags was visualized. At working length (WL)-5, and WL-2, the maximum tag penetration depth for the GuttaCore group into the dentinal tubules was, respectively, 96 μm and 48 μm, whereas the values in the thermafil group were 109 μm, and 55 μm, respectively. Conclusions: Our results clearly show that Thermafil and GuttaCore can fill oval-shaped canals in appropriate way. Furthermore, we can state that the GuttaCore obturator allows to preserve the same filling ability than Thermafil obturator, in view of the fact that there was no difference, in terms of GPFA, SFA, and VA between the two different carrier-based obturation technique

Special Issue “Recent Advances in Biomaterials and Dental Disease” Part I

Oral cavities provide an entry point for food and nutrients [...

Effectiveness of Three Agents in Pulpotomy Treatment of Permanent Molars with Incomplete Root Development: A Randomized Controlled Trial

The aim of this study was to investigate and compare, radiographically and clinically, the impacts of calcium-silicate based-cement (CSBC), nano-hydroxyapatite and platelet-rich fibrin (PRF) as pulpotomy agents in permanent immature molars with incomplete root development. Sixty-three participants (63 permanent immature molars) were included in this study. The patients were randomly divided into three equal groups. Fast setting MTA (MM-MTA), nano-hydroxyapatite and platelet-rich fibrin were used as pulpotomy agents. The teeth were evaluated clinically and radiographically after 6 and 12 months by two blinded examiners. Apical closure and pulp canal obliteration percentages were recorded. The in vitro reaction of the tested materials after a 7-day immersion period of the different materials in phosphate-buffered solution was analyzed using scanning electron microscopy to associate the in vitro mineralization with in vivo pulp canal obliteration percentages. Data were analyzed using Chi-square and ANOVA tests (α = 0.05). No significant difference was found between the three tested groups in terms of clinical and radiographic success (p > 0.05). All cases demonstrated evidence of root growth, including complete apical closure or continued apical closure. At 12 months, complete apical closure was found among the MM-MTA group (50%), nano-hydroxyapatite group (55%) and platelet-rich fibrin group (60%) (p > 0.05). After 12 months, pulp canal obliteration was more observed in the MM-MTA and nano-hydroxyapatite groups than in the PRF group (p < 0.05). MM-MTA (auto-mixed), NHA (hand-mixed) and PRF (autologous) could be used as pulpotomy agents since they exhibit comparable high clinical and radiographic success rates. However, the fact that the groups managed with MM-MTA and NHA have a higher tendency to canal obliteration might indicate that PRF should be considered the first choice material as pulpotomy agent, as it would make retreatment considerably easier. View Full-Text Keywords: pulpotomy; permanent molars with incomplete root development; MM-MTA; nano-hydroxyapatit