Influence of benzalkonium chloride on dentin \u3bcTbs and MMPs activity

Purpose/aim: Benzalkonium chloride (BAC) is a nitrogenous cationic surface-acting agent containing a quaternary ammonium group claimed to inhibit dentin matrix metalloproteinases (MMPs) in addition to its disinfectant ability. The aim of the studywas to investigate the adhesive bond strength and the dentin enzymatic activity of a multi-mode universal adhesive system (All-Bond Universal; Bisco Inc., ABU) and an experimental adhesive with BAC blended within its formulation (SBAC, Bisco Inc.,) employed in etch-and rinse (E&R) or self-etch (SE) mode. Materials and methods: A standardized smear layer was created using a 180-grit silicon-carbide paper on 32 middle/ deep human dentin surfaces. Specimens were assigned to the following groups (n = 8) according to the adhesive procedure: G1: SBAC employed in E&R mode after dentin etching with 35% phosphoric acid for 15 s. G2: SBAC employed in SE mode on untreated dentin. G3: ABU employed in E&R mode after dentin etching with 35% phosphoric acid for 15 s. G4: application of ABU in SE mode on untreated dentin. All adhesives were applied according to manufacturer\u2019s instructions and cured for 20 s. Composite buildups were created on the bonded surfaces, then specimens were cut for microtensile bond strength test (TBS) and stressed to failure at a crosshead speed of 1mm/min after 24-h storage in artificial saliva at 37 \u25e6C. TBS data were analyzed using two-way ANOVA and Tukey\u2019s multiple comparison tests. Additionally, enzymatic activity was evaluated using a zymographic assay on protein extracts obtained from adhesive-treated dentin powder of each tested group. Results: Results of TBS showed no significant differences after 24h storage in artificial saliva within the four groups. Furthermore, zymographic analysis revealed increased expression of dentin endogenous MMP-2 and -9 after application of All Bond Universal in SE mode, while in the E&R mode the expression of the MMP-2 decreased and MMP-9 was inhibited. SBAC employed in SE mode increased the expression of MMP-2, while inactivating the MMP-9. The application of SBAC in the E&R mode also inactivated MMP-9, while MMP-2 activity was significantly decreased. Conclusions: Further studies and longer aging are needed to clarify the influence of BAC blended within the adhesive formulation in improving bond longevity and dentin MMPs inhibition

Experimental use of an acrolein-based primer as collagen cross-linker for dentine bonding

Objectives The objective of the present study was to investigate the long-term effect of 0.01% acrolein (ACR) aqueous solution, employed as an additional primer, on the mechanical durability and enzymatic activity of resin-dentine interfaces created with a simplified etch-and-rinse adhesive. Methods Dentine surfaces were etched with 35% phosphoric acid for 15 s, rinsed and blot-dried. Specimens were then assigned to: Group 1: dentine pre-treated with 0.01% ACR aqueous solution for 1 min and bonded with Adper Scotchbond 1 XT (SB1XT), a 2-step etch-and-rinse adhesive; Group 2: SB1XT was applied on untreated acid-etched dentine (control). Resin composite build-ups were made using Filtek Z250. Microtensile bond strength was tested by stressing sectioned specimens to failure immediately or after 1 year of storage in artificial saliva at 37 °C. Zymography and in-situ zymography assays were performed for examining dentine matrix metalloproteinase (MMP) activities. Results The use of 0.01% ACR as conditioning primer appeared to have contributed better to preservation of bond strength over time without affecting immediate bond strength. Zymography and in-situ zymography showed reduction in MMP activities after the application of ACR. Conclusion Dentine collagen cross-linking produced by an ACR-based primer increases the longevity of resin-dentine bonds by reinforcement of the adhesive interface and reduction of dentine MMP activities. Further studies are required to evaluate the potential in vivo and in vivo cytotoxicity of ACR. Clinical significance The acrolein-based primer is a potentially useful clinical bonding tool because it demonstrates good collagen cross-linking ability within a clinically-acceptable working time. Although a low ACR concentration was employed in the present study, the cytotoxicity of ACR should be tested prior to clinical use

Cross-linking effect on dentin bond strength and MMPs activity

Objective: The objectives of the study were to evaluate the ability of a 1-ethyl-3 (3-dimethylaminopropyl) carbodiimide (EDC)-containing primer to improve immediate bond strength of either self-etch or etch-and-rinse adhesive systems and to stabilize the adhesive interfaces over time. A further objective was to investigate the effect of EDC on the dentinal MMPs activity using zymographic analysis. Methods: Freshly extracted molars (n = 80, 20 for each group) were selected to conduct microtensile bond strength tests. The following groups were tested, immediately or after 1-year aging in artificial saliva: G1: Clearfil SE (CSE) primer applied on unetched dentin, pretreated with 0.3. M EDC water-solution for 1. min and bonded with CSE Bond; G2: as G1 but without EDC pre-treatment; G3: acid-etched (35% phosphoric-acid for 15s) dentin pretreated with 0.3. M EDC, then bonded with XP Bond (XPB); Group 4 (G4): as G3 without EDC pre-treatment. Further, gelatinase activity in dentin powder treated with CSE and XPB with and without EDC pre-treatment, was analyzed using gelatin zymography. Results: The use of 0.3. M EDC-containing conditioner did not affect the immediate bond strength of XPB or CSE adhesive systems (p. >. 0.05), while it improved the bond strength after 1. year of aging (p. <. 0.05). Pre-treatment with EDC followed by the application of CSE resulted in an incomplete MMPs inactivation, while EDC pretreatment followed by the application of XPB resulted in an almost complete inactivation of dentinal gelatinases. Significance: The μTBS and zymography results support the efficacy of EDC over time and reveal that changes within the dentin matrix promoted by EDC are not adhesive-system-dependent

Extensive DNA methylome rearrangement during early lamprey embryogenesis

Abstract DNA methylation (5mC) is a repressive gene regulatory mark widespread in vertebrate genomes, yet the developmental dynamics in which 5mC patterns are established vary across species. While mammals undergo two rounds of global 5mC erasure, teleosts, for example, exhibit localized maternal-to-paternal 5mC remodeling. Here, we studied 5mC dynamics during the embryonic development of sea lamprey, a jawless vertebrate which occupies a critical phylogenetic position as the sister group of the jawed vertebrates. We employed 5mC quantification in lamprey embryos and tissues, and discovered large-scale maternal-to-paternal epigenome remodeling that affects ~30% of the embryonic genome and is predominantly associated with partially methylated domains. We further demonstrate that sequences eliminated during programmed genome rearrangement (PGR), are hypermethylated in sperm prior to the onset of PGR. Our study thus unveils important insights into the evolutionary origins of vertebrate 5mC reprogramming, and how this process might participate in diverse developmental strategies

Role of chlorhexidine on long-term bond strength of self-adhesive composite cements to intraradicular dentin

Purpose: To examine the effect of CHX pre-treatment on long-term bond strength of fiber posts luted with self-adhesive resin cements. Materials and Methods: Seventy-two single-rooted teeth were selected for root canal treatment and post space preparation. The tested self-adhesive cement/post combinations were (N = 36): 1. RelyX Fiber-Posts luted with RelyX Unicem; 2. Rebilda Posts luted with Bifix SE Cement. For both self-adhesive cements, half of the specimens (experimental groups) were luted after the application of a solution of 2% CHX, while no CHX application was performed for the remaining specimens (control groups). Luted specimens were cut and used for push-out bond strength evaluation immediately, and after storage in artificial saliva for 6 months or 1 year. Additional specimens were processed for quantitative interfacial nanoleakage analysis. Results: ANOVA showed that the variable times of storage had a significant influence on the results (p 0.05) was found. Tukey's pairwise post-hoc test showed that the radicular bond strength decreased with time of storage. In particular, a significant difference was found between T0 and T1y, but not between T0 and T6m. In contrast, in terms of pretreatment, no significant reduction in push-out bond strength was observed, irrespective of the aging time. Conclusion: CHX pretreatment did not prevent bond strength degradation of fiber posts luted with self-adhesive cements