IADR Abstract Archives
Functional Remineralization of Demineralized Dentin Using Polymer-Induced Liquid-Precursor (PILP) Process
Objectives: Preliminary experiments to determine if functional remineralization (restoration of hydrated mechanical properties) of artificial carious lesions could be achieved using a novel method, polymer-induced liquid-precursor (PILP) mineralization. The PILP process consists of the addition of anionic polymers to a supersaturated mineralization solution to induce a liquid-phase amorphous calcium phosphate precursor for remineralization.
Methods: Dentin specimens were prepared from extracted non-carious human teeth with exposed surface area=6mm2, polished to 0.25µm, and demineralized for 66hours in 40mL of 0.05M acetic acid buffered with 2.2mM Ca2+ and PO43- (pH=5.0). Artificial lesions were exposed to PILP mineralization for 0,7,14, or 28days. Poly-L-aspartic acid (Pasp, MW=27KDa) was used as the polymeric process-directing agent at 100μg/mL concentration. The solutions also contained 4.5mM Ca2+ and 2.1mM PO43- at pH=7.4 and 37°C. Sagittal sections through the lesions were characterized using AFM-based wet nanoindentation to determine mechanical properties and micro x-ray computed tomography (µXCT) to determine mineral density profiles. Reduced elastic modulus (Er) and hardness (H) were measured at 4µm intervals and plotted against distance (0-180µm). The area under the curves was compared to complementary data from control portions of the dentin (protected by nail varnish during demineralization). Data were analyzed using one-way ANOVA and Holm-Sidak statistical methods.
Results:
| Area under curve (% change from lesion)
| ||||
| Control
| Artificial Lesion
| 7-Day
| 14-Day
| 28-Day
|
Er [GPa-µm]
| 3,220±100
| 1,170±140*
| 1,770±120*+ (51%)
| 2,040±50*+ (74%)
| 2,200±220*+ (91%)
|
H [GPa-µm]
| 130±6
| 46±5*
| 65±8* (40%)
| 68±3* (46%)
| 82±10*+ (77%)
|
µXCT Mineral Profile [HU- µm]
| -------------
| 1,281,000±77,000
| 1,493,000±32,000+ (17%)
| 1,622,000±20,000+ (27%)
| 1,674,00±47,000+ (31%)
|
*significantly different from control +significantly different from lesion (p<0.05, n=4, mean±S.E.M.)
| |||||
Conclusions: The novel PILP method of mineralization may effectively restore mechanical properties of artificial carious lesions produced using acetate buffer. The nanomechanical and mineral density data show similar trends, with no significant differences between 14-day and 28-day results.
Supported: NIH/NIDCR Grant R01DE016849-04S1