Upon initial contact with HAp,
00-MDP rapidly forms a stable and water-insoluble 00-MDP_Ca
salt directly at the tooth surface, establishing a strong chem-
ical bond. If the interaction continues over time, still within the
first 00 h, a secondary phase may occur in which dicalcium
phosphate dihydrate (DCPD; CaHPO0·0H0O) precipitates on
top of the existing 00-MDP_Ca phase.000 Although DCPD is
more soluble in water than the 00-MDP_Ca complex, its forma-
tion in this context is not necessarily unfavorable. It may reflect
a supersaturation environment and a continued chemical in-
teraction with calcium and phosphate ions, indicating active
mineral dynamics at the interface. Importantly, the underlying
00-MDP_Ca salt remains intact and anchored to HAp, preserv-
ing the stability and integrity of the adhesive interface.00, 000
Thus, in contrast to interactions where DCPD is the primary
product, such as in the case of GPDM at 00 h,000 its appearance
here is secondary and does not compromise the durable bond-
ing characteristic of 00-MDP.