Rena Takahashi

Effect of primer treatment on bonding of resin cements to zirconia ceramic

OBJECTIVES To evaluate and compare bond strengths of different primers and resin cements to silica-based and zirconia ceramics. METHODS Silica-based and zirconia ceramic specimens were ground flat with #600-grit SiC paper. The ceramic surfaces were airborne-particle abraded and then divided into 11 groups of seven each: untreated (control); and conditioned with one of the six primers in combination with a resin cement from the same manufacturer as follows: Bistite II/Tokuso Ceramic Primer, Linkmax/GC Ceramic Primer, RelyX ARC/RelyX Ceramic Primer, Panavia F 2.0/Clearfil Ceramic Primer, and Resicem/Shofu Porcelain Primer and Resicem/AZ Primer. Stainless steel rods were bonded to the ceramic surfaces using one of the five resin cements. After 24-h water storage, the tensile bond strengths were tested using a universal testing machine and failure modes were examined. RESULTS Conditioning with primers containing a silane coupling agent (all the primers except AZ Primer) significantly enhanced bond strengths of resin cements to silica-based ceramic. For zirconia ceramic, Resicem/AZ Primer exhibited significantly higher bond strength than the other groups except Panavia F 2.0/Clearfil Ceramic Primer. The predominant failure mode of the groups conditioned with primers containing a phosphonic acid monomer (AZ Primer) or a phosphate ester monomer (Clearfil Ceramic Primer and Tokuso Ceramic Primer) was cohesive failure in cements whereas that with the other primers was adhesive failure at the zirconia surfaces. SIGNIFICANCE The use of primers containing a silane coupling agent improved resin bonding to silica-based ceramic. On the other hand, the use of primers containing a phosphonic acid monomer or a phosphate ester monomer improved resin bonding to zirconia ceramic.

The effect of curing conditions on the dentin bond strength of two dual-cure resin cements

PURPOSE The purpose of this study was to determine the effect of the curing condition (i.e., the curing mode and restoration thickness) on the tensile bond strength of a dual-cure resin cement applied to dentin. METHODS Indirect composite resin disks (1, 2, and 3mm in thickness) were prepared. The irradiance of a halogen light curing unit through each disk was measured by a curing radiometer. A measurement was also taken for the condition with no disk. Following this, two dual-cure resin cements, Panavia F2.0 and Panavia V5, were polymerized in either dual-cure mode or self-cure mode to bond the composite resin disk to the flat dentin surface. The specimens were sectioned and subjected to a microtensile bond strength (μTBS) test after 24h of water storage. The data were statistically analyzed by two-way ANOVA followed with multiple comparisons by post-hoc Tukeys test (α=0.05). RESULTS The irradiance values [mW/cm2] measured through indirect composite resin disks were 600 (0mm), 200 (1mm), 90 (2mm), and not detected (3mm). Two-way ANOVA indicated that both the curing condition and the type of resin cement affected the μTBS (p<0.001). The μTBS results for Panavia V5 bonded to dentin were significantly higher than those of Panavia F2.0 bonded to dentin (p<0.05). CONCLUSIONS The curing condition affected the tensile bond strength of the dual-cure resin cements to dentin. A newly developed resin cement, Panavia V5, showed higher dentin bonding than Panavia F2.0 in both dual- and self-cure modes.

Resin Coating Technique for Protection of Pulp and Increasing Bonding in Indirect Restoration

A resin coating technique has been widely advocated in recent years. A combination of a dentin bonding system and a flowable composite is applied on the exposed dentin surfaces immediately after tooth preparation and before taking the final impression. The resin coating is beneficial to both minimize pulpal irritation and enhance the bond strength of a resin cement to dentin. Recently introduced thin-film coating materials based on all-in-one adhesive technology are used for resin coating of crown restorations. Thin-film coating materials can be applied in a single clinical procedure and followed by created a barrier-like film layer on the prepared dentin. Therefore, the resin coating technique may play an important role to protect the dentin physically, chemically, and biologically. The coating materials also have the potential to cover exposed sound enamel and dentin, leading to maximum tooth structure preservation.

CXCL14 Acts as a Specific Carrier of CpG DNA into Dendritic Cells and Activates Toll-like Receptor 9-mediated Adaptive Immunity

CXCL14 is a primordial chemokine that plays multiple roles in tumor suppression, autoimmune arthritis, and obesity-associated insulin resistance. However, the underlying molecular mechanisms are unclear. Here, we show that CXCL14 transports various types of CpG oligodeoxynucleotide (ODN) into the endosomes and lysosomes of bone marrow-derived dendritic cells (DCs), thereby activating Toll-like receptor 9 (TLR9). A combination of CpG ODN (ODN2395) plus CXCL14 induced robust production of IL-12 p40 by wild-type, but not Tlr9-knockout, DCs. Consistent with this, ODN2395-mediated activation of DCs was significantly attenuated in Cxcl14-knockout mice. CXCL14 bound CpG ODN with high affinity at pH 7.5, but not at pH 6.0, thereby enabling efficient delivery of CpG ODN to TLR9 in the endosome/lysosome. Furthermore, the CXCL14-CpG ODN complex specifically bound to high affinity CXCL14 receptors on DCs. Thus, CXCL14 serves as a specific carrier of CpG DNA to sensitize TLR9-mediated immunosurveillance.

Root Caries Management: Evidence and Consensus Based Report

Root caries are becoming an increasingly common clinical problem, especially as aged-society. This report is based on the clinical practice guideline which offers a practical expert review of managing root caries with the best scientific evidence and the general consensus of expert clinicians. Root caries should be managed differently from coronal caries, and a shift of its strategy from “early-detection and early-treatment” to “early-detection and long-term management” is called for. Once the restorative treatment is chosen, it is often more advantageous to use glass-ionomer than resin composite. In addition, as we face a super-aged society now, in today’s dentistry setting, silver diammine fluoride (SDF) with high demineralization inhibitory effect is being re-evaluated as the “rescue material” (material for emergency cases) for root caries.