Effect of immediate and delayed dentin sealing on the fracture strength, failure type and Weilbull characteristics of lithiumdisilicate laminate veneers

OBJECTIVES Adhesion on dentin is less reliable than on enamel, which could affect the durability of laminate veneers (LV). Immediate dentin sealing (IDS) is suggested instead of delayed dentin sealing (DDS) to overcome hypersensitivity and prevent debonding from dentin. This study evaluated the effect of IDS and DDS on the durability of Li2Si2O5 laminate veneers in vitro. METHODS Window preparations were made on the labial surfaces of sound maxillary central incisors (N=50). They were randomly divided into five groups: Group 1: Enamel only+H3PO4+Adhesive (control); Group 2: <1/4 dentin+H3PO4+DDS (2 weeks later); Group 3: Complete dentin+H3PO4+DDS (2 weeks later); Group 4: <1/4 dentin+H3PO4+IDS; Group 5: Complete dentin+H3PO4+IDS. Li2Si2O5 laminate veneers (e.max Press) were bonded to the labial surfaces of the teeth with adhesive resin cement (Variolink Veneer). IDS layers were silicacoated (CoJet System) and silanized (ESPE-Sil). The teeth with their bonded laminates were thermocycled (10.000× cycles) and then subjected to static loading (1mm/min). Failure type and location after debonding were classified. Data were analyzed using ANOVA and Tukey's post hoc test (α=0.05). Two-parameter Weibull distribution values including the Weibull modulus, scale (m) and shape (0), values were calculated. RESULTS Mean fracture strength (N) per group in descending order was as follows: Group 5 (576±254), Group 4 (478±216), Group 1 (473±159), Group 2 (465±186), and Group 3 (314±137). The presence of complete dentin exposure sealed with DDS after 2 weeks on the bonded surface (Group 3) resulted in significantly lower fracture strength results than those in group 5 with IDS (p=0.034). Weibull distribution presented higher shape (0) for Group 1 (3.67), than those of other groups (2.51-2.89). Failure types were predominantly adhesive failure between the cement and the laminate veneer in Groups 1, 2, 4 whereas Group 3 presented more often complete adhesive failures between the cement and dentin. In Group 5, failures showed some IDS and cement with or without ceramic fracture attached on the tooth. SIGNIFICANCE When laminate veneers are bonded to a large dentin substrate, application of immediate dentin sealing improves adhesion and thereby, the fracture strength of Li2Si2O5 laminate veneers

Exploring delay-based tcp congestion control

The thesis begins with a short review of TCP and new congestion control schemes in Chapter 2. Following this, chapter 3 explores the question of whether correlation between congestion and the delay signal of each flow on a link is really necessary for delay-based congestion control to function. It also explores the behaviour of the delay-based AIMD (DB-AIMD) algorithm in various network environments. Chapter 4 presents an experimental study into the effectiveness of a particular delay-based methodology for emptying network queues where congestion is detected. Finally, chapter 5 discussed some practical issues involved in how one measures RTT in practice for the purposes of congestion control

Additional file 1: of Identification of the novel activity-driven interaction between synaptotagmin 1 and presenilin 1 links calcium, synapse, and amyloid beta

Spectral FRET analysis of the GFP and RFP intensities. Primary neurons were transfected with GFP-PS1 (negative FRET control, n = 12 cells), RFP-GFP fusion (R-G, positive FRET control, n = 24) or GFP-PS1-RFP (PS1 conformation FRET probe, n = 10). The GFP was excited by argon laser at 488 nm wavelength, and the emission intensities of GFP and RFP within the 513 ± 10.57 nm and 598 ± 10.57 nm spectral bandwidth of the Metadector, respectively, were collected every 3 minutes for the duration of 33 minutes (middle and bottom graphs, respectively). The arrow indicates the time point of 50 mM KCl stimulation. No significant change in the GFP or RFP fluorescence emission intensity (no photobleaching), or the R/G ratio was observed in the G-PS1 and R-G transfected cells. The change in the R/G ratio after KCl stimulation was detected only in G-PS1-R transfected cells due to increased FRET efficiency/change in PS1 conformation. The black line shows mean ± SEM values. (TIF 1663 kb