Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2014 Dec;93(12):1270-6.
doi: 10.1177/0022034514549997. Epub 2014 Sep 8.

Doxycycline-encapsulated nanotube-modified dentin adhesives

S A Feitosa  1 , J Palasuk  2 , K Kamocki  3 , S Geraldeli  4 , R L Gregory  5 , J A Platt  3 , L J Windsor  5 , M C Bottino  6
Affiliations
Comparative Study

Doxycycline-encapsulated nanotube-modified dentin adhesives

S A Feitosa et al. J Dent Res. 2014 Dec.

Abstract

This article presents details of fabrication, biological activity (i.e., anti-matrix metalloproteinase [anti-MMP] inhibition), cytocompatibility, and bonding characteristics to dentin of a unique doxycycline (DOX)-encapsulated halloysite nanotube (HNT)-modified adhesive. We tested the hypothesis that the release of DOX from the DOX-encapsulated nanotube-modified adhesive can effectively inhibit MMP activity. We incorporated nanotubes, encapsulated or not with DOX, into the adhesive resin of a commercially available bonding system (Scotchbond Multi-Purpose [SBMP]). The following groups were tested: unmodified SBMP (control), SBMP with nanotubes (HNT), and DOX-encapsulated nanotube-modified adhesive (HNT+DOX). Changes in degree of conversion (DC) and microtensile bond strength were evaluated. Cytotoxicity was examined on human dental pulp stem cells (hDPSCs). To prove the successful encapsulation of DOX within the adhesives-but, more important, to support the hypothesis that the HNT+DOX adhesive would release DOX at subantimicrobial levels-we tested the antimicrobial activity of synthesized adhesives and the DOX-containing eluates against Streptococcus mutans through agar diffusion assays. Anti-MMP properties were assessed via β-casein cleavage assays. Increasing curing times (10, 20, 40 sec) led to increased DC values. There were no statistically significant differences (p > .05) in DC within each increasing curing time between the modified adhesives compared to SBMP. No statistically significant differences in microtensile bond strength were noted. None of the adhesives eluates were cytotoxic to the human dental pulp stem cells. A significant growth inhibition of S. mutans by direct contact illustrates successful encapsulation of DOX into the experimental adhesive. More important, DOX-containing eluates promoted inhibition of MMP-1 activity when compared to the control. Collectively, our findings provide a solid background for further testing of encapsulated MMP inhibitors into the synthesis of therapeutic adhesives that may enhance the longevity of hybrid layers and the overall clinical performance of adhesively bonded resin composite restorations.

Keywords: biocompatible materials; bonding; collagen; drug delivery systems; matrix metalloproteinase; stem cells.

PubMed Disclaimer

Conflict of interest statement

The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.

Figures

Figure 1.
Figure 1.
Graphic depicting the degree of conversion (DC) for control (SBMP) and experimental adhesives that were polymerized for 10, 20, and 40 sec. Increasing curing times led to a general increase in DC values: 60.7%-64.1% (10 sec), 63.7%-69.7% (20 sec), and 70.8%-72.6% (40 sec). There were no statistically significant differences (p > .05) in DC within each curing time between the modified adhesives compared to SBMP. DOX, doxycycline; HNT, halloysite nanotube; SBMP, Scotchbond Multi-Purpose.
Figure 2.
Figure 2.
Micrographs of halloysite nanotubes (HNTs; Dragonite 1415JM, Applied Minerals Inc., New York, NY, USA): (A) scanning electron microscope (25,000×; bar, 1 µm) and (B) transmission electron microscope (98,000×; bar, 100 nm). Representative scanning electron microscope micrographs of fractured surfaces: (C, D) SBMP with HNTs (100×, 5,000×) and (E, F) SBMP with doxycycline-encapsulated HNTs (100×, 5,000×). Arrows show rodlike structures approximately 1 to 2 µm in length representing the HNTs incorporated into the experimental adhesive. SBMP, Scotchbond Multi-Purpose.
Figure 3.
Figure 3.
Representative macrophotographs of agar diffusion test against Streptococcus mutans at 96 hr of incubation: (A) SBMP (Scotchbond Multi-Purpose), (B) HNT (SBMP with halloysite nanotubes), (C) CHX (0.12% chlorhexidine; positive control), and (D) HNT+DOX (SBMP with doxycycline-encapsulated HNTs). Mean inhibition zone of 0.12% chlorhexidine and HNT+DOX was 21.0 ± 1.0 mm and 12.0 ± 0.0 mm, respectively. No inhibition zone was observed from SBMP and HNT. (E) Cytotoxicity of adhesive resin eluates released from specimens tested on human dental pulp stem cells. No significant differences (p = .225) were found comparing all groups of study and dilutions tested.
Figure 4.
Figure 4.
Representative images of Coomassie blue–stained sodium dodecyl sulfate–polyacrylamide gel electrophoresis gels of β-casein cleavage assays. (A) Negative control: 50 mM Tris with 0.2 M NaCl, 10 mM CaCl2, and 1 µM ZnCl2 (pH 7.4). (B) Positive control: 0.1% doxycycline (DOX) solution (Sigma). DOX eluates: (C) day 1, (D) day 7, and (E) day 14. As depicted, more β-casein is present in panel E compared to the negative control (50 mM Tris) at 2 hr, which is not seen in day 1 and 7 aliquots.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Al-Ahmad A, Ameen H, Pelz K, Karygianni L, Wittmer A, Anderson AC, et al. (2014). Antibiotic resistance and capacity for biofilm formation of different bacteria isolated from endodontic infections associated with root-filled teeth. J Endod 40:223-230. - PubMed
    1. Bottino MC, Batarseh G, Palasuk J, Alkatheeri MS, Windsor LJ, Platt JA. (2013a). Nanotube-modified dentin adhesive-physicochemical and dentin bonding characterizations. Dent Mater 29:1158-1165. - PubMed
    1. Bottino MC, Kamocki K, Yassen GH, Platt JA, Vail MM, Ehrlich Y, et al. (2013b). Bioactive nanofibrous scaffolds for regenerative endodontics. J Dent Res 92:963-969. - PMC - PubMed
    1. Breschi L, Mazzoni A, Ruggeri A, Cadenaro M, Di Lenarda R, De Stefano Dorigo E. (2008). Dental adhesion review: aging and stability of the bonded interface. Dent Mater 24:90-101. - PubMed
    1. Breschi L, Martin P, Mazzoni A, Nato F, Carrilho M, Tjaderhane L, et al. (2010). Use of a specific MMP-inhibitor (galardin) for preservation of hybrid layer. Dent Mater 26:571-578. - PMC - PubMed

Publication types

MeSH terms

LinkOut - more resources