Polyaspartic acid enhances dentine remineralization bonded with a zinc-doped Portland-based resin cement

Aim To ascertain whether biomimetic phosphoprotein analogues (polyaspartic acid (PAS) and sodium trimetaphosphate (TMP)) improve bonding efficacy and dentine remineralization ability of a novel zinc-doped Portland-based resinous sealing cement. Methodology Bonding procedures were performed on phosphoric acid-etched dentine, and several groups were established regarding biomimetic analogue application: (1) no application, (2) PAS-treated dentine and (3) dentine treated with a mixture of PAS and TMP. Raman spectroscopy and microtensile bond strength (MTBS) with fracture analysis by scanning electron microscopy were carried out. MTBS values were compared by ANOVA, Student-Newman-Keuls and Student's t-tests (P < 0.05 and P < 0.01, respectively). Results Twenty-four hour MTBS values were not affected by the different bonding procedures. After 6 months, MTBS decreased in those groups in which the phosphoproteins analogues were not applied (P < 0.05). When PAS was applied, MTBS was maintained after 6 months (P > 0.05). The novel material bonded without primer application induced bioactive crystal (calcium carbonate and Ettringite) precipitation onto the etched dentine and augmented the degree of crystallinity at the hybrid layer. Mineral-to-matrix ratio was increased at the hybrid layer of the PAS-treated specimens; this primer was also able to catalyse dentine remineralization, without an increase in crystallinity. Conclusions PAS application onto demineralized dentine produced an inhibition or delay of mineral phase crystallization, enhancing the remineralization potential of the Portland microfillers at the resin-dentine bonded interface.