Development and evaluation of a new dental adhesive for biomimetic remineralization of adhesive interfaces

A recent alternative to promote restorative durability is biomimetic remineralization. It uses two phosphoprotein analogs from dentinogenesis and could be performed using a two-step self-etching adhesive containing bioactive calcium phosphates in the adhesive and a new biomimetic analogue (EDTF, ethylene diamine tetramethylene phosphonate) in the primer, acting as the two different types of analogues Already known. Thus, an experimental adhesive was prepared and pre-mixed with mono-calcium phosphate monohydrate and beta-phosphate tri-calcium in the bond. In addition, primers were developed according to the experimental design. A primer with no analogs and no particles in the bond (one negative control, CN), one containing the most used analogues in the literature trimetaphosphate (TMP) of sodium and polyacrylic acid (APA) (TMP / APA - positive control, CP), and others containing EDTF / TMP, EDTF / APA or EDTF alone were prepared. A group with only particles in the bond and without the analogs in the primer was also used. These adhesive systems were applied in artificially simulated carious dentin (DAC) and in healthy dentin of extracted human molars. After periods of 24h and 6 months of storage, they were evaluated by microtraining, nanoinfiltration and Micro-Raman spectroscopy of the interface (hybrid layer) and the underlying dentin. Microtraction data were analyzed statistically with two-way ANOVA and Tukey's test (α = 5%). In the microtraction of the hybrids, there was only statistical difference (p <0.05) in the EDTF / TMP groups, showing an increase in union strength after 6 months and in the EDTF / APA group, which had a decline. In DAC, there was a decrease in CN, EDTF / TMP and EDTF / APA groups (p <0.05). In the analysis of nanoinfiltration in DAC, the CN revealed the presence of cracks and degradation in the immediate dentin region, and in the adhesive layer after aging, which was not observed in the other groups. In Micro-Raman spectroscopy it was possible to observe the presence of more marked mineralization in the CP, EDTF, EDTF / TMP and only particles groups, but this was not observed in the CN and EDTF / APA groups. It is concluded that the best results for adhesion and remineralization of dentin affected by caries are obtained with the use of traditional analogues (TMP / APA) or with EDTF alone and associated with TMP, without affecting the adhesion to the healthy dentin.Uma recente alternativa para promover uma maior durabilidade às restaurações é a remineralização biomimética. Ela utiliza dois análogos de fosfoproteínas da dentinogênese e poderia ser realizada utilizando um adesivo autocondicionante de dois passos contendo fosfatos de cálcio bioativos no adesivo e um novo análogo biomimético (EDTF, etilenodiamino tetrametileno-fosfonato) no primer, agindo como os dois diferentes tipos de análogos já conhecidos. Assim, um adesivo experimental foi preparado e aplicado com mistura prévia com fosfato de mono-cálcio mono-hidratado e beta fosfato tri-cálcio no bond. Além disso, foram desenvolvidos primers de acordo com o delineamento experimental. Um primer sem análogos e sem partículas no bond (controle negativo, CN), um contendo os análogos mais utilizados na literatura trimetafosfato (TMP) de sódio e ácido poliacrílico (APA) (TMP/APA - controle positivo, CP), e outros contendo EDTF/TMP, EDTF/APA ou somente EDTF foram preparados. Um grupo somente com partículas no bond e sem os análogos no primer também foi usado. Estes sistemas adesivos foram aplicados em dentina afetada por cárie (DAC) simulada artificialmente e em dentina hígida de molares humanos extraídos. Após períodos de 24h e 6 meses de armazenamento, eles foram avaliados por teste de microtração, nanoinfiltração e espectroscopia Micro-Raman da interface (camada híbrida) e da dentina subjacente. Os dados de microtração foram analisados estatisticamente com ANOVA dois fatores e Teste de Tukey (α=5%). Na microtração dos hígidos só houve diferença estatística (p<0,05) nos grupos EDTF/TMP apresentando um aumento na resistência de união após 6 meses e no grupo EDTF/APA que teve um declínio. Em DAC, houve uma queda nos grupos CN, EDTF/TMP e EDTF/APA (p