Intraradicular dentine silanization by a new silicon-based endodontic sealer

What is it about?

We synthesize a new silicon-based endodontic sealer that reacts at room and body temperature. The sealer is initially hydrophilic allowing flowing and filling every accessory tubule of the root canal and turns hydrophobic during polymerization. A hydrophobic surface of dentinal walls could limit fluid penetration by reversing capillary pressure and reducing the space between the intraradicular dentinal wall and the endodontic sealer by covalent bonds. For this purpose, we did a surface treatment on dentinal walls to expose hydroxyl groups usable for silanization by a covalent attachment between the tetraethyl orthosilictate (TEOS) and dentinal wall, transforming dentin walls in a hydrophobic surface; while TEOS also acts as cross-linking of the sealer which ensured a good sealing. The sealer polymerization was followed by Fourier transform infrared spectroscopy (FTIR), Quartz crystal microbalance (QCM-D), water contact angle (WCA) and rheological analysis. Radiopacity, resistance to dislodgment and dimensional alterations are in accordance with international standards (ISO standard 6876/2002). Working and setting time may be manipulated by varying TEOS and catalyst concentration. Zero filtration was obtained in the liquid filtration test.

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Why is it important?

In this work, we synthesize a new hydrophobic sealer that reacts at room and body temperature; and we propose a strategy to overcome the incompatibility between hydrophilic and hydrophobic materials: we use carboxyterminal domains to do a surface treatment to hydrophobicize the dentinal walls by expose hydroxyl groups usable for silanization by a covalent attachment between the hydrophobic sealer and hydrophilic dentine, which ensured an adequate sealing that may produce null liquid permeation. The characterization of the sealer was followed by Fourier transform infrared spectroscopy (FTIR) to identify the functional groups, by Quartz crystal microbalance (QCM-D) to quantify the loss of ethanol during the curing process, by water contact angle (WCA) to analyze the hydrophobicity; and a study of the rheological properties of the endodontic sealer was conducted, which may help to assess the formation of the structure and the time-dependence behavior.