A zinc-doped endodontic cement facilitates functional mineralization and stress dissipation at the dentin surface.
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AuthorPérez-Álvarez, Mayra C.; Osorio, Estrella; Lynch, Christopher D.; Toledano-Osorio, Manuel; Toledano Pérez, Manuel; Osorio Ruiz, Raquel
Toledano-Osorio M. A zinc-doped endodontic cement facilitates functional mineralization and stress dissipation at the dentin surface. Med Oral Patol Oral Cir Bucal. 2018 Nov 1;23(6):e646-e655. [http://hdl.handle.net/10481/53639]
SponsorshipThis work was supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER) [MAT2017-85999-P MINECO/AEI/FEDER/UE]
Objective: The purpose of this study was to evaluate nanohardness and viscoelastic behavior of dentin surfaces treated with two canal sealer cements for dentin remineralization. Material and Methods: Dentin surfaces were subjected to: i) 37% phosphoric acid (PA) or ii) 0.5 M ethylenediaminetetraacetic acid (EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite), respectively. Samples were stored in simulated body fluid during 24 h or 21 d. The intertubular and peritubular dentin were evaluated using a nanoindenter to assess nanohardness (Hi). The load/displacement responses were used for the nano-dynamic mechanical analysis to estimate complex modulus (E*) and tan delta (δ). The modulus mapping was obtained by imposing a quasistatic force setpoint to which a sinusoidal force was superimposed. AFM imaging and FESEM analysis were performed. Results: After 21 d of storage, dentin surfaces treated with EDTA+calcypatite, PA+calcypatite and EDTA+oxipatite showed viscoelastic discrepancies between peritubular and intertubular dentin, meaning a risk for cracking and breakdown of the surface. At both 24 h and 21 d, tan δ values at intertubular dentin treated with the four treatments performed similar. At 21 d time point, intertubular dentin treated with PA+oxipatite achieved the highest complex modulus and nanohardness, i.e., highest resistance to deformation and functional mineralization, among groups. Conclusions: Intertubular and peritubular dentin treated with PA+oxipatite showed similar values of tan δ after 21 d of storage. This produced a favorable dissipation of energy with minimal energy concentration, preserving the structural integrity at the dentin surface.