One of the most important properties of a resin-modified glass-ionomer (RMGI) is its sustained release of fluoride and therefore potential caries inhibition capability. Objectives: 1) to measure the fluoride release of three RMGI cements: an experimental cement (EXP, Kerr), Rely X Luting (RXL, 3M), and Fuji Plus (FJP, GC America); and 2) to model the kinetics of the fluoride release process. Methods: Specimens (n=3) were prepared using a ring mold (F /h: 20/1mm) and stored in 0.85% NaCl solution at 37° C. The fluoride release was measured at pre-determined time intervals (1d/7d/1m/2m/4m). Non-linear regression analyses were performed on cumulative fluoride release as a function of time. Results: ANOVA analysis revealed that EXP had significantly higher fluoride release (p < 0.05) than the other two cements at all time intervals. The fluoride release process can be described by the sum of a short-term and a long-term processes: F_t = F_I*t/(T_I + t) + K_II*t^1/2; where F_I and T_I are the total fluoride release and half-life for the short-term process; and K_II is the diffusion coefficient for the long-term process.

	Cumulative Fluoride Release, ug/cm2				Parameters From Model
	1day	7days	1month	4months	FI , ug/cm2	TI , days	KII , m g/(cm2day1/2)
EXP	246± 26a*	559± 25a	1040± 25a	1975± 34a	119	0.48	167
RXL	179± 11b	405± 13b	813± 25b	1476± 45b	261	7.92	113
FJP	159± 19b	388± 25b	739± 26c	1346± 30c	192	4.35	106

*Means with the same letter within the same column are not statistically different at p < 0.05.

Conclusions: The kinetics of the fluoride release can be modeled by the sum of a short-term and a long-term process. EXP had significantly higher (p < 0.05) level of fluoride release than the other two cements at all time intervals, and it has the largest diffusion coefficient among all cements studied.

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