A Remineralizing Root Caries Restorative Material

METHOD: A light-cured, resin–based composite material was formulated from resin (30%) and calcium phosphate/pre-polymer filler (70%). This experimental cement (EC) was compared to Fuji II-LC glass ionomer cement (GIC) by evaluating the following properties: 1) Flexural strength (FS): specimens (1x4x25mm, n=5) were light-cured 1min/side, stored 24h (37°C, 100% humidity), and tested in 3-point bending (0.5mm/min). 2) Ion release (IR): disk-shaped specimens (1x13mm, n=3) were light-cured 1min/side, and suspended in saline solution (100mL/disc, 37°C). At scheduled intervals, aliquots of saline solution were removed and analyzed for pH, fluoride (F), calcium (Ca), and phosphate (PO4). 3) Microleakage: 24 cavities were drilled into the buccal and lingual dentin surfaces of 12 extracted caries-free human molars, then filled with EC, GIC, or EC coated with sealant (n=8). The teeth were thermocycled (2000 cycles between 5 and 55°C), then AgNO3 was used as a tracer.

RESULTS: FS (MPa), pH, & IR (mmol/L)

	FS	pH-1d	pH-56d	F-1d	F-56d	Ca-1d	Ca-56d	PO4-1d	PO4-56d
GIC	54	7.22	7.02	0.06	0.51	0.04	0.22	-0.01	0.00
	(4)a	(0.03)	(0.03)	(0.01)	(0.05)	(0.00)	(0.01)	(0.0)	(0.01)
EC	55	7.33	6.95	0.04	0.11	0.23	0.14	0.09	0.12
	(6)a	(0.02)	(0.04)	(0.01)	(0.02)	(0.04)	(0.01)	(0.02)	(0.02)

Microleakage: The median, 25th and 75th percentile for EC were 0.38, 0.21, 0.58; for EC-coated 0.23, 0.20, 0.38; and for GIC 0.10, 0.10, 0.35, respectively. There was no significant difference between groups (Kruskal-Wallis ANOVA on ranks, p= 0.106). CONCLUSION: Compared to GIC, EC gave similar results for FS and microleakage. Solution ion concentrations of EC specimens were supersaturated with respect to hydroxyapatite and fluorapatite at day 1, and fluorapatite at day 56. Therefore, EC has potential to remineralize mineral-deprived dentin. Support: ADAF, NIST, and NIDCR Grant DE13298.