Polymer Nanocarriers for Dentin Adhesion (original) (raw)
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To promote adhesion to dentin, the mineral phase from the substrate has to be removed and the voids left by mineral should be filled with the adhesive resin that undergoes complete in situ polymerization to form the hybrid layer (1). Two main strategies are used to create dentin bonding. The first strategy involves the use of etch-and-rinse adhesives, which require the treatment of dentin with phosphoric acid (PA) to remove the smear layer and to demineralize the underlying dentin, exposing a dense filigree of organic-matrix fibrils, essentially represented by type I collagen (2). This is followed by the application of a primer/bonding adhesive, but a decreasing gradient of resin monomer diffusion within the acid-etched dentin results in a phase of demineralized collagen matrix at the base of the hybrid layer (3). The second strategy uses self-etching adhesives, which are based on the polymerizable acidic monomers that simultaneously condition/prime and bond dentin. With the use of this technique, it is generally accepted that there is less discrepancy between the depth of deminer-alization and the depth of resin infiltration (3). Matrix metalloproteinases (MMPs) are a family of structurally related zinc-dependent endopeptidases (4). Matrix metalloproteinases 2, 8, 9 and 20 are present in dentin and contribute to the organization and minerali-zation of the dentin matrix. Matrix metalloproteinases play a role not only in dentin matrix modulation during caries progression (4, 5), but also in collagen degradation at the dentin-resin bonded interfaces, jeopardizing the longevity of bonded restorations (2, 6). A decrease of bonding efficacy over time has been reported and attributed to the action of host-derived MMPs (7-9). Therefore, one of the proposed strategies used to increase the longevity of adhesive restorations has been to inhibit the MMP-induced degradation of dentin collagen (2, 10). It was shown, by zymographic analysis, that zinc or other divalent metals may reduce the expression of some MMPs (11, 12). It has also been recently reported that zinc effectively reduces the MMP-mediated degradation of collagen in dentin beams stored in a rich ZnCl 2 solution (13). Zinc has a structural role in proteins. It seems that subtle conformational changes occur in col-lagen following zinc binding and lead to the protection of sensitive cleavage sites of metalloproteinases. Thus, the zinc concentration around matrix-bound MMPs might be very important in determining their activity on dentin collagen. In view of the clinical demand on engineered dental tissue, new adhesive/primers formulations including zinc in their composition-zinc-doped adhesives-should be tested. Effective inhibitors of MMPs included in resin-dentin bonding interfaces may protect the seed crystallite-sparse collagen fibrils of the scaffold from degradation before they can be remineralized (14). Osorio R, Yamauti M, Osorio E, Roma´n JS, Toledano M. Zinc-doped dentin adhesive for collagen protection at the hybrid layer. Eur J Oral Sci 2011; 119: 401-410. Ó 2011 Eur J Oral Sci The aim of the study was to ascertain whether the addition of zinc to adhesives may decrease metalloproteinase-mediated collagen degradation without affecting bonding efficacy. Human dentin beams were treated with phosphoric acid, with Clearfil SE Bond Primer or with Clearfil SE Bond Primer plus ZnCl 2 (2 wt%). Acid-etched dentin was infiltrated with Single Bond, Single Bond plus ZnCl 2 (2 wt%), or Single Bond plus ZnO nanoparticles (10 wt%), and Clearfil SE Bond-primed dentin was infiltrated with Clearfil SE Bonding resin, Clearfil SE-Bonding resin with ZnCl 2 (2 wt%), or Clearfil SE-Bonding resin with ZnO nanoparticles (10 wt%). The C-terminal telopeptide concentrations were determined 24 h, and 1 and 4 wk after treatment. Microtensile bond strength to dentin was determined for the tested adhesives. Matrix metallo-proteinases-mediated collagen degradation occurred in acid-etched and SE-primed dentin. Resin infiltration decreased collagen degradation. Lower collagen degradation was found for SE Bond than for Single Bond. Zinc-doped Single Bond resin always reduced collagen degradation, the ZnO particles being more effective than ZnCl 2. Zinc-doped SE Bond reduced the liberation of C-terminal telopeptide only at 24 h. Bond strength to dentin was not decreased when Zn-doped resins were employed, except when ZnCl 2 was added to SE Primer. Zinc-doped resin reduced collagen degradation in Single Bond hybrid layers, but did not affect bond strength. The addition of zinc to SE Bond had no beneficial effects.
Al-Azhar Dental Journal for Girls, 2017
Objectives: This study was designed to evaluate the ability of two experimental Zn-doped-adhesive (zinc chloride and zinc oxide nanoparticles) alone or with calcium phosphate nanoparticles to induce therapeutic effect on the bonded resin-dentin interface using two adhesive systems(total etch and self-etch). Material and Method: eighty human premolar dentin surfaces were assigned into four main groups (n=20) according to zinc doping (A1), the universal single bond doped with zinc chloride (ZnCl 2), (A2) the universal single bond doped with zinc oxide nanoparticles (NZnO), (A3) the universal single bond doped with zinc chloride +calcium phosphate nanoparticles (NACP) (A4) the universal single bond (as a control). Each group was further subdivided into tow subgroups according to the adhesive technique either etch and rinse (B1) or self-etch (B2). Prepared samples were stored in distilled water for 24h, and then submitted to microtensile bond strength testing. Two samples from each group were prepared for observation of nanoleakage by the scanning electron microscope (SEM). Data was collected and statistically analyzed. Results: In the total etch adhesive technique, the highest mean value was recorded in group(A4 B1), followed by (A2B1) and (A3B1) groups; with the least mean value for the (A1B1) group. Using the self-etch adhesive technique, the highest mean value was recorded in the (A2B2) and (A4B2) groups followed by (A3B2) group with the least mean value for (A1B2) group. Comparing the adhesive techniques, there was statistically significant difference with higher mean value for the etch and rinse adhesive technique except with NZnO group. Conclusion: Addition of zinc to the universal single bond significantly affected the microtensile bond strength except with ZnO nanoparticles group in the self-etch adhesive technique.
Journal of Clinical and Experimental Dentistry
Background: This study aimed to evaluate the remineralization potential and bioactivity of adhesives, containing amorphous calcium phosphate (ACP) and calcium silicate (CS) nanoparticles (NPs). Material and methods: In this study, dentin slices (n=60) were prepared and etched with phosphoric acid. Next, they were divided into two groups: pre-and post-immersion in a simulated body fluid (SBF) for three weeks. The two groups were also divided into five subgroups (n=6 per subgroup), including the control (0 wt.% NPs); adhesives containing 1 wt.% and 2.5 wt.% (CS) nanoparticles; and adhesives containing 1 wt.% and 2.5 wt.% ACP nanoparticles. The remineralization potential and bioactivity of the adhesives were evaluated. The shear bond strength of the samples (n=18) was also assessed using a universal testing machine. Results: The present results revealed that the adhesive containing ACP and CS nanoparticles showed bioactivity and remineralization potential without any reduction in the bond strength. Conclusions: The outcomes revealed that Cs and ACP nanoparticles induced mineralization in the dentin and incorporation of these nanoparticles to dentin bonding agents could improve the bio-functionalization of dentin bond.
Polymers
This is a narrative review of the literature assessing the potential effectiveness of doping dentin polymeric adhesives with zinc compounds in order to improve bonding efficacy, remineralization and protection against degradation. A literature search was conducted using electronic databases, such as PubMed, MEDLINE, DIMDI and Web of Science. Through our search, we found literature demonstrating that Zn-doped dentin adhesives promote protection and remineralization of the resin-dentin interfaces. The increased bioactivity has also facilitated dentinal tubules’ occlusion by crystals’ precipitation contributing to improved sealing efficacy of restorations. Loading dentin adhesives with zinc gives rise to an increase of both crystallinity of mineral and crosslinking of collagen. The main role of zinc, in dentin adhesives, is to inhibit collagen proteolysis. We concluded that zinc exerts a protective effect through binding at the collagen-sensitive cleavage sites of matrix-metalloprotein...
Nanoparticles antidegradation activity at bonded dentin
2019
The objective was to assess doxycycline (Dox) and zinc (Zn) doped nanoparticles' (NPs) potential to protect the resin-dentin interface from cariogenic biofilm. Three groups ofpolymeric NPs were tested: unloaded, loaded with zinc and with doxycycline. NPs were appliedafter dentin etching. The disks were exposed to a cariogenic biofilm challenge in a Drip-FlowReactor during 72 h and 7 d. Half of the specimens were not subjected to biofilm formation butstored 72 h and 7 d. LIVE/DEAD® viability assay, nano-dynamic mechanicalassessment, Raman spectroscopy and field emission electron microscopy (FESEM) analysiswere performed. The measured bacterial death rates, at 7 d were 46% for the control group, 51%for the undoped-NPs, 32% for Dox-NPs, and 87% for Zn-NPs; being total detected bacteriareduced five times in the Dox-NPs group. Zn-NPs treated samples reached, in general, thehighest complex modulus values at the resin-dentin interface over time. Regarding the mineralcontent, Zn-NPs-tre...
Nanomaterials, 2021
Tubule occlusion and remineralization are considered the two main goals of dentin hypersensitivity treatment. The objective is to assess the ability of dentifrices containing zinc-doped polymeric nanoparticles (NPs) to enduringly occlude the dentinal tubules, reinforcing dentin’s mechanical properties. Fifteen dentin surfaces were acid-treated for dentinal tubule exposure and brushed with (1) distilled water, or with experimental pastes containing (2) 1% of zinc-doped NPs, (3) 5% of zinc-doped NPs, (4) 10% of zinc-doped NPs or (5) Sensodyne®. Topographical and nanomechanical analyses were performed on treated dentin surfaces and after a citric acid challenge. ANOVA and Student–Newman–Keuls tests were used (p < 0.05). The main results indicate that all pastes produced tubule occlusion (100%) and reinforced mechanical properties of intertubular dentin (complex modulus was above 75 GPa). After the citric acid challenge, only those pastes containing zinc-doped NPs were able to mainta...
Journal of Dentistry, 2019
To evaluate the effect of addition of zinc oxide and copper nanoparticles (ZnO/CuNp) into universal adhesives, on antimicrobial activity (AMA), cytotoxicity (CTX), water sorption (WS) and solubility (SO), microhardness (MH) and in vitro degree of conversion (DC), as well as resin-dentin microtensile bond strength (μTBS), nanoleakage (NL) and in situ DC. Methods: ZnO/CuNp (0% [control]; 5/0.1 and 5/0.2 wt%) were added in Prime&Bond Active (PBA) and Ambar Universal (AMB). The AMA was evaluated against Streptococcus mutans. For CTX, Saos-2 cell-line was used. For WS and SO, specimens were tested for 28d. For MH, specimens were tested after 24 h and 28d and for in vitro DC, specimens were evaluated after 24 h. After, the adhesives were applied to flat dentine surfaces, composite resin build-ups, specimens were sectioned to obtain resin-dentine sticks. It was evaluated in μTBS, NL and in situ DC after 24 h of water storage. ANOVA and Tukey's test were applied (α = 0.05). Results: The addition of 5/0.2 ZnO/CuNp increase AMA and WS, but decrease the SO when compared to control (p < 0.05). The CTX and μTBS were maintaining with adhesive-containing ZnO/CuNp (p > 0.05). MH, in vitro DC and in situ DC was significant increase (AMB) or maintaining (PBA) with ZnO/CuNp addition. However, significantly lower NL was observed for ZnO/CuNp groups (p < 0.05). Conclusions: The addition of ZnO/CuNp in the tested concentrations in universal adhesive systems may be an alternative to provide antimicrobial activity and improves the integrity of the hybrid layer, without jeopardizing biological, adhesives and mechanical properties. Significance: This is the first study that demonstrates that the addition of zinc oxide and copper nanoparticles in concentrations up to 5/0.2 wt% in two universal adhesive systems is a feasible approach and may be an alternative to adhesive interfaces with antimicrobial properties and less defects in the resin-dentin interface. 1. Introduction Composite resins are increasingly gaining more space in restorative dentistry, offering such advantages as aesthetics and less invasive preparation techniques [1,2]. However, the lack of durable dental adhesives and secondary caries are considered one of the main problems with contemporary adhesive restorations, negatively affecting their clinical success [2,3]. On the other hand, removal of composite resins leads to loss sound tooth structure, increasing cavity volume and needing a more complex restoration [4]. Thus, this reduced longevity