Location of MMPs in human radicular dentin and the effects of MMPs inhibitor on the bonding stability of fiber posts to radicular dentin.

This study explored the location of MMP-2, -3, -8 in human root dentin and the inhibition of EGCG/EGCG-3Me on dentin-originated collagen proteases activities. Also, the study evaluated EGCG/EGCG-3Me modified etch-and-rinse adhesives (Single Bond 2, SB 2) for their bonding stabilities to intraradicular dentin. Immunostaining and liquid chip analysis demonstrated that MMP-2 and MMP-8 are widely distributed in root dentin while MMP-3 shows a higher fluorescence intensity in the middle and apical third of the root. The contents of MMP-2, -3 and -8 varies in different locations of human tooth root and MMP-2 has the highest content than MMP-3 and MMP-8 at each third of teeth root. Both EGCG and EGCG-3Me showed an inhibitory effect on the root dentin-derived MMPs in a concentration dependent manner (P < 0.05) and the inhibitory activity of EGCG-3ME was stronger than that of EGCG at the same concentration (P < 0.05). EGCG and EGCG-3Me were incorporated separately into the adhesive SB 2 at concentrations of 200, and 400 µg/mL respectively. The immediate push-out strength of SB 2 was not compromised by EGCG/EGCG-3Me modification. EGCG/EGCG-3Me modified adhesive had higher push-out strength than SB 2 after thermocycling, showing no correlation with concentration.

[Advances in color stability of resin cements and its influence on all-ceramics restorations].

Resin cements have been widely employed for bonding all-ceramic restorations in clinical practice, its color stability is directly related to long-term prosthetic effect of restorations. Discoloration of resin cements can be attributed to two causes: endogenous factors are generally related to material compositions and initiation mechanism of polymerization; exogenous factors are mainly related to stimulation of local oral environment. Color stability of resin cements has close relationship with esthetic effect of all-ceramic restorations. The aim of this literature review was to make a presentation and discussion systematically about color stability of resin cements commonly used clinically, its influence factors and influence on all-ceramic restorations, so as to provide a reference for the application of all-ceramic restorations.

A novel dentin bonding scheme based on extrafibrillar demineralization combined with covalent adhesion using a dry-bonding technique.

Dentin bonding is a dynamic process that involves the penetration of adhesive resin monomers into the extrafibrillar and intrafibrillar demineralized collagen matrix using a wet-bonding technique. However, adhesive resin monomers lack the capacity to infiltrate the intrafibrillar space, and the excess water that is introduced by the wet-bonding technique remains at the bonding interface. This imperfectly bonded interface is inclined to hydrolytic degradation, severely jeopardizing the longevity of bonded clinical restorations. The present study introduces a dentin bonding scheme based on a dry-bonding technique, combined with the use of extrafibrillar demineralization and a collagen-reactive monomer (CRM)-based adhesive (CBA). Selective extrafibrillar demineralization was achieved using 1-wt% high-molecular weight (MW) carboxymethyl chitosan (CMCS) within a clinically acceptable timeframe to create a less aggressive bonding substance for dentin bonding due to its selectively extrafibrillar demineralization capacity. CMCS demineralization decreased the activation of in situ collagenase, improved the shrinking resistance of demineralized collagen, and thus provided stronger and more durable bonding than traditional phosphoric acid etching. The new dentin bonding scheme that contained CMCS and CBA and used a dry-bonding technique achieved an encouraging dentin bonding strength and durability with low technical sensitivity. This bonding scheme can be used to improve the stability of the resin-dentin interface and foster the longevity of bonded clinical restorations.

[Effects of epigallocatechin-3-gallate modification on the bonding stability of an etch-and-rinse adhesive to intraradicular dentin].

Objective: To evaluate the effects of epigallocatechin-3-gallate (EGCG) modification on the bonding stability of an etch-and-rinse adhesive to intraradicular dentin, and to find a new strategy to improve the stability of bonding interface. Methods: EGCG was incorporated into Single Bond 2 (SB2) with the concentration of 200 mg/L and 400 mg/L respectively to fabricated experimental adhesives group A and group B, while Single Bond 2 without EGCG was used as control group. Laser scanning confocal microscope (LSCM) and scanning electron microscope (SEM) were used to observe the bacterial biofilm adherent to the surface of the cured adhesive. Micro-Raman spectrum was used to test the degree of conversion (DC) of adhesives. The push-out bond strength of instant testing and aging with thermocycling for 5 000 times were also tested. Results: Group A and group B showed inhibiting effect on the biofilm formation of Enterococcus faecalis and performed better with higher concentration. No significant differences were detected in DC among group A ([69.73±0.68]%), group B ([69.03±1.65]%) and control group ([70.06±1.62]%) (P>0.05), and the immediate push-out bond strength of control group ([10.45±2.00] MPa) was not compromised compared to group A ([10.02±2.03] MPa) and group B ([9.95±3.03] MPa) (P>0.05). After thermocycling for 5 000 times, group A ([7.01±1.39] MPa) and group B ([7.62±1.88] MPa) showed significantly higher push-out bond strength than control group did ([5.08±1.56] MPa) (P<0.05). Conclusions: EGCG modified etch-and-rinse adhesives showed anti-bacterial effect and enhanced bonding stability of intraradicular dentin-adhesive interfaces.

A DNA clone encoding the full-length infectious genome of odontoglossum ringspot tobamovirus and mutagenesis of its coat protein gene.

A full-length DNA clone encoding the genome of odontoglossum ringspot tobamovirus (ORSV) was synthesized and placed adjacent to a bacteriophage T7 RNA polymerase promoter. Capped-RNA transcripts produced in vitro were highly infectious when mechanically inoculated onto seedlings of Nicotiana benthamiana and Oncidium Gower Ramsey. A representative clone, designated pOT2, caused a disease phenotype identical to that produced by parental viral RNA. ELISA, Western blot analysis, Northern blot hybridization and electron microscopy verified the infectivity of pOT2. A coat protein deficient mutant of the clone, pO delta CP1, was produced with the initiation codon of the coat protein cistron of ORSV abolished. Transcripts from pO delta CP1 were infective, able to move in N. benthamiana but produced no coat protein. This demonstrates that the coat protein was dispensable for RNA replication and for movement. This is believed to be the first report of an ORSV infectious clone driven by a T7 RNA polymerase promoter.