1,721,321 research outputs found
ROMA. ARCHITETTURA E CITTÀ. Idee, visioni e progetti
No full textAR MAGAZINE numero 121. Rivista dell'Ordine degli Architetti di Roma e provincia, dedicato all'indagine sugli archivi di architettura. "Roma sognata. Gli archivi di architettura dal Nolli alle nuove poetiche radicali", un percorso di 448 pagine ricco di immagini e materiali inediti. All’interno dello stesso si pubblica “Roma. Architettura e città. Idee, visioni e progetti” un ampia rassegna della ricerca visuale dell'autore corredata da un testo in cui sono circostanziate le ragioni e le modalità della stess
Cemento endodontico ad elevata bioattività
No full textCementi calcio silicatici fotopolimerizzabili e bioattiviBioactive light curable calcium silicate cement
An in vitro study on dentin demineralization and remineralization: Collagen rearrangements and influence on the enucleated phase
No full textDentin remineralization is of clinical relevance in the therapy of caries and dentin hypersensitivity. This study is aimed at gaining more insights on a molecular scale, through IR spectroscopy, into dentin demineralization and remineralization. The dentin demineralization by ethylenediaminetetraacetic acid, EDTA (17%, 2 h) significantly altered the secondary structure distribution of collagen, upon loss of interaction with calcium ions. To investigate dentin remineralization, previously demineralized human dentin slices were soaked in Dulbecco's Phosphate Buffered Saline (DPBS) or Hank's Balanced Salt Solution HBSS, in close contact with three commercial cements used as sustained releasing sources of Ca2+ and OH− ions (i.e. calcium hydroxide- and calcium silicate-based cements). IR spectroscopy showed the occurrence of remineralization under these conditions. Collagen did not lose its ability to chelate Ca2+, and these interactions allowed collagen to rearrange into a conformation similar to that of sound dentin. This process appeared slower in HBSS than DPBS, as also shown by the lower degree of maturation of the inorganic phase enucleated in the former medium (amorphous calcium phosphate versus B-type carbonated apatite). Collagen appeared to act as a spatial constraint to crystal deposition, affecting crystallinity and carbonate content of the enucleated phase. Remineralization was found to strongly depend on the calcium releasing ability of the cements. The fast formation of a rough apatite biocoating may represent a favorable clinical condition in the context of mineralized tissue regeneration
Long-term outcome of non-surgical root canal treatment: a retrospective analysis
No full textThis study investigated the long-term clinical outcome of root canal treatment. 240 root-treated teeth (n = 61 patients) were initially classified on the basis of radiographic presence/absence of initial apical periodontitis (IAP) and clinical data. The final outcome measure was the periapical healing (healed/disease). The outcome at 6-9 months was correlated with the outcome at 10 years following treatment. Prognostic factors for the periapical healing were assessed. Extraction data were recorded. Univariate and multivariate logistic regression analysis was used to identify risk indicators for apical periodontitis (AP) development. Chi-square analysis was performed to evaluate a possible relationship between the 6-9 months outcome and the final outcome related to IAP. Mean observation time was 14 ± 3.7 years. Survival rate was 84.6% and healing rate was 79% (10-19 years). Predictors of outcome (p < .05) were considered statistically significant. Multivariate logistic regression analysis showed that initial pulpal and periapical status and the quality of root canal filling as assessed two-dimensionally were independent predictors of outcome. The 6-9 months evaluation appears to be an indicator for the final outcome of primary root canal treatment both in the presence and in the absence of IAP. An initial radiolucency associated with an unsatisfactory quality and extent of root canal filling significantly diminishes the possibility of achieving long-term radiographic success. For those with uncertain healing at 6-9 months (91%), clinicians should consider the high healing rate when estimating the prognosis and adjust the decision making accordingly
Appearance of the root canal walls after preparation with NiTi rotary instruments: a comparative SEM investigations
No full textThe aim of this study was to evaluate, in vitro, with scanning electron microscope (SEM), the appearance of root canal walls shaped by three different rotary NiTi techniques and one conventional manual technique in human extracted teeth. Four different instruments were used: K3, Hero 642, RaCe and K-file. Each sample was irrigated with 5 ml of 5% NaOCl and 5 ml of 3% H2O2 and EDTA, Rc-Prep (1 ml). Each sample was prepared for SEM observation and analyzed in the coronal, middle and apical third, comparing its aspect with a predefined scale of four different parameters: presence of smear layer, pulpal debris, inorganic debris and surface profile. The apical third showed significantly more pulpal and inorganic debris, smear layer and a high number of surface profile irregularities. No significant difference was found at the coronal, middle and apical thirds between manual and rotary techniques for inorganic debris, smear layer and surface profile. Much pulpal debris were found in the apical third for K3 and RaCe compared with Hero 642 and K-file. In conclusion, mechanical rotary techniques with NiTi instruments produced quite similar results compared with a conventional manual technique using K-files. The present study demonstrated that dentin and pulpal debris, the morphology of smear layer and surface profile were only partially influenced by the type of endodontic instruments. The apical third was the anatomical area with greater amount of debris and smear layer.</p
A poly(2-hydroxyethyl methacrylate)-based resin improves the dentin remineralizing ability of calcium silicates
No full textBioactive polymeric composites have received great attention for their capability to remineralize the dentin tissue. This study was aimed at evaluating if a poly(HEMA-co-TEGDMA) resin (HEMA: 2-hydroxyethyl methacrylate; TEGDMA: triethyleneglycol dimethacrylate) may increase the in vitro apatite forming ability of a calcium silicate cement (CaSi), in view of developing a hydrophilic light-curable composite bio-remineralizing restorative material (R-CaSi). To this purpose, the following experiments were carried out: (1) In vitro apatite forming ability of R-CaSi and CaSi was comparatively assessed by micro-Raman spectroscopy after immersion of the cement disks in Dulbecco's Phosphate Buffered Saline (DPBS) at 37 °C for 1–28 days; (2) Previously demineralized human dentin slices were soaked for 7 days in close contact with the CaSi and R-CaSi cements as well as poly(HEMA), poly(TEGDMA) and poly(HEMA-co-TEGDMA), and then were comparatively analyzed by IR spectroscopy. Micro-Raman spectroscopy showed that in calcium phosphate nucleation tests, the B-type carbonated apatite deposit formed on R-CaSi was thicker than that on CaSi; therefore, the poly(HEMA-co-TEGDMA) resin proved able to increase the in vitro apatite forming ability of the calcium silicate-based cement. Both cements were found to induce dentin remineralization, R-CaSi to a higher extent, in agreement with the calcium phosphate nucleation tests. This result may be ascribed to the positive role played by the polymeric component, which was found to interact with collagen and to chelate calcium ions. Upon remineralization, collagen underwent conformational rearrangements and the formed apatite phase, rather than a simple deposit, was intimately bound to the collagen matrix, thanks to the calcium ions chelated by it
Differential hydrolytic degradation of dentin bonds when luting carbon fiber posts to the root canal.
No full textOBJECTIVE: The purpose of the study was to evaluate the effect of water storage, adhesive system and root canal region on the hydrolytic degradation of dentin bonds to carbon fiber posts.
STUDY DESIGN: Fiber posts were bonded to the root canals using different adhesive systems and composites: SB1 XT group (Scotchbond 1 XT/RelyX ARC), OBF group (One Up Bond F Plus/Ionotite F), and AB2 group (All Bond 2/C&B) After water storage (10 days), all roots were sectioned into 1 mm beams and divided into coronal or apical group. The specimens were stored in water at 22-26 °C temperature for 15 or 60 days and tested for microtensile bond strength at a crosshead speed of 0.9 mm/min after the calculation of the bonding area. Statistical analysis was performed with ANOVA followed by Tukey test to detect differences between groups (α=0.05). SEM investigation was performed to determine the mode of fracture.
RESULTS: Bond strength at coronal and apical half showed significant differences between experimental groups both after 15 and 60 days of water storage. Premature failures were observed in 16-20% of specimens before storage in water.
CONCLUSIONS: For the bonding systems tested, clinicians should consider that bond strength inside the root canal at apical half is lower than at coronal half irrespective of the adhesive system. The adhesion within the root canal is possible for SB1 XT and OBF groups unlike the AB2 group where adhesion to root canal dentine is not reliable. Nevertheless, apical half represents the worst scenario in which is possible to obtain a durable adhesion
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
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