Avaliação de um adesivo autocondicionante incorporado com um agente remineralizante em dentina hígida e desmineralizada artificialmente: estudo in vitro

Abstract

The development and use of bioactive materials and techniques that allow the mainte- nance of dental tissues represent a conservative and minimally invasive approach. Howe- ver, the durability of treatments involving adhesive bonding to the dentin substrate is still not completely satisfactory, especially those performed on decayed dentin. In view of this, the aim of the present study was to evaluate the influence on the bonding interface and the remineralizing potential of a self-etching adhesive incorporated with bioactive glass (VBA) on artificially demineralized dentin (ADD) and sound dentin (DH). For this, the groups were divided as follows: DH; ADD; VBA+DH and VBA+DDA. A commer- cial adhesive was used for direct incorporation of VBA at 10% (w/v). After that, eighty healthy third molars were selected and stored in a thymol solution at 0.01% (w/v). Half of the sample was subjected to pH cycling to obtain the ADI. To evaluate the bond stren- gth (RU), the microtensile test (n=8) was performed after 24 hours and 6 months of sto- rage, nanoleakage (n=3) and micropermeability (n=3). To evaluate dentin remineraliza- tion, Knoop microhardness tests (n=3) were performed after 24 hours and 3 months and Fourier transform infrared spectroscopy (FT-IR) (n=3) immediately and after 30 days of storage. Stored specimens were kept in artificial saliva at 37°C and the solutions were changed monthly. Evaluating the microtensile data, it was possible to observe that the VBA+DDA group was effective in preserving the bond strength after 6 months of aging (p=0.887). In the observations of nanoleakage, it was found that treatment with VBA provided less water accumulation in DH and ADD. For micropermeability, in DH the groups showed no absorption of fluorescein. In ADD, the group treated with VBA sho- wed a lower degree of absorption and better dentin sealing. When analyzing the micro- hardness data, it was found that the VBA+DDA group promoted an increase in micro- hardness at all depths tested after 3 months of storage in artificial saliva. The VBA+DH group was effective in increasing microhardness at depths of 70 and 100 μM (p=0.006 and p=0.015 respectively). The FT-IR analysis showed signs of bioactivity with the ap- pearance of apatite peaks in the group treated with VBA in the two evaluated periods. The incorporation of VBA to a self-etching adhesive system proved to be an effective method for preserving bond strength after aging, improving the microhardness of healthy and artificially demineralized dentin, inducing the precipitation of minerals at the adhe- sive interface, and also being able to guarantee a proper sealing of the hybrid layer.