Post-bleaching Fluoridation and Demineralization

In This Article

Abstract

Background Topical fluoride agents have been shown to be the most effective method in treating demineralized enamel after in-office bleaching treatments. Thus, this study aimed to examine the effects of two different post-bleaching fluoridation agents: 1.5% titanium tetrafluoride (TiF₄) (9200 ppm) and 2.1% sodium fluoride (NaF) (9500 ppm), on the calcium loss of enamel after an acidic challenge.

Methods Ten maxillary premolars were sectioned into four pieces and then divided into the following four groups: Group 1: Control, kept in artificial saliva, no treatment; Group 2: 38% hydrogen peroxide (HP); Group 3: 38% HP followed by 1.5% TiF_4; Group 4: 38% HP followed by 2.1% NaF solution. The specimens were subjected to demineralization for 16 days, refreshing the solution every 4 days; that is, on the 4th, 8th, 12th, and 16th days. Calcium ion (Ca²⁺) concentration was determined by an atomic absorption spectrophotometer. Data were analyzed using Friedman and Wilcoxon tests (p = 0.05).

Results The loss of Ca²⁺ in each of the test groups was compared with that of the control group, depicting that there was a statistically significant difference among the groups after 4, 8, 12, and 16 days and in total (p < 0.05). The calcium released from the fluoride-applied groups was lower when compared with the 38% HP and control group. At the end of the 16th day, the total amount of calcium released from the TiF₄-treated samples (9.12 mg/mL) was less than from the NaF-treated samples (13.67 mg/mL) (p < 0.05).

Conclusions Regarding the results of our in vitro study, the risk of further demineralization was significantly reduced with the use of TiF₄ and NaF after bleaching with 38% HP. TiF₄was found to be more effective in preventing Ca²⁺ release owing to acid attack when compared with NaF. In the case of an intra-oral acidic exposure, the use of topical 1.5% TiF₄ and 2.1% NaF agents might be beneficial after bleaching with 38% HP.

Table 1. Test groups
Groups	N	Bleaching agent	Fluoride application	pH	F application time
1	10	No agent	---------		---------
2	10	38% HP	--------		--------
3	10	38% HP	2.1% NaF	~1.2	1 minutes
4	10	38% HP	1.5% TiF₄	~1.2	1 minutes

Table 2. Calcium ion (Ca ²⁺) release from the bleached specimens treated with 1.5% TiF ₄ and 2.1% NaF in mm ² (mg/ml)
	N		4th day	8th day	12th day	16th day	Total
Control group	10	Mean	3,59	3,2	3,72	4,55	15,07
		Std dev	0,54	0,59	1,23	0,89	1,81
		Min.	3,01	2,46	2,46	2,74	12,6
		Max.	4,93	4,38	6,58	5,75	18,36
38% HP	10	Mean	5,75	5,18	5,56	5,95	22,44
		Std dev	1,6	1,52	0,71	0,37	2,52
		Min.	3,83	3,01	4,66	5,48	18,36
		Max.	7,95	8,5	6,85	6,58	27,68
38% HP + NaF	10	Mean	2,05	3,15	3,94	4,52	13,67
		Std dev	0,83	0,58	1,01	0,83	1,86
		Min.	0,82	2,19	2,46	3,29	10,68
		Max.	3,01	4,11	5,75	6,03	15,61
38% HP + TiF4	10	Mean	1,15	1,94	2,66	3,37	9,12
		Std dev	0,92	1,54	0,63	0,48	2,4
		Min.	0	0	1,64	2,46	4,93
		Max.	2,46	4,11	3,56	3,83	11,5

Table 3. Statistical differences between test groups
Materials	4th day	8th day	12th day	16th day	Total
Control × 38% HP	0.007	0.017	0.022	0.005	0.005
Control × 38% HP + NaF	0.036	0.798	0.444	0.878	0.721
Control × 38% HP + TiF4	0.005	0.059	0.167	0.059	0.005
38% HP × 38% HP + NaF	0.009	0.005	0.022	0.009	0.005
38% HP × 38% HP + TiF4	0.005	0.013	0.007	0.005	0.005
38% HP + NaF × 38% HP + TiF4	0.074	0.241	0.047	0.059	0.017