Evaluation of the remineralizing capacities of modified saliva substitutes in vitro.

In this in vitro study the effects of various calcium and phosphate additions to a commercially available saliva substitute on remineralization of demineralised dentin were investigated. Bovine dentin specimens (n=70) were prepared. Before and after demineralisation (37 degrees C, pH 5.0, 5 days), one-quarter of each specimens surface was covered with nail varnish (control sound/demineralised tissue). Specimens were exposed either to original Saliva natura (SN 0) or to three modified versions (SN 1, SN 2 and SN 3) formulated with different degrees of saturation with respect to octacalciumphosphate (OCP) and dicalcium phosphate dihydrate (DCPD) for 2 and 5 weeks (37 degrees C). An aqueous solution (Buskes remineralizing solution) served as positive control (PC). Differences in mineral loss (deltadeltaZ) and lesion depth (deltaLD) before and after storage were evaluated from microradiographs. After both storage periods dentin specimens immersed in SN 0 revealed significantly higher mineral losses (indicated by deltadeltaZ) and higher lesion depths (indicated by deltaLD) compared to all other solutions (p<0.05; ANOVA). Specimens stored in SN 1 and 3 showed significantly higher mineral losses compared with PC (p<0.05). No differences could be observed between SN 2 and PC (p>0.05). Only SN 2 significantly remineralized from 2 to 5 weeks storage (p<0.05; t-test). An experimental Saliva natura solution (SN 2) with S(OCP)=2 and S(DCPD)=1.4 showed highest remineralizing capacity. Similar or better remineralization could not be achieved with slightly higher or lower saturated solutions.