Figura 3.

pH-cycling studies evaluating the dose-response or pH-response of fluoridated dentifrices for caries prevention

PROTOCOL	DENTAL TISSUE	RESPONSE VARIABLE	RESULTS
pH-cycling	Human enamel	CSH x TMR [Ten Cate, et al.92 (1985)]	The NaF dentifrice was found to be extremely effective in reducing the progression of caries in enamel
Re:14d, 37°C, on the weekends and before De
De: for 6h/day in 40 ml of acid buffer containing 2.0 mM Ca, 2.0 mM PO4, 0.075 M acetate, pH 4.3
Treatment: with slurry 1:4 in water for 5 min/Re for 17 h in 20 mL of a mineralizing solution containing 1.5 mM Ca, 0.9 mM PO4, 0.15 M KCl and 20 mM cacodylate buffer, pH 7.0 [as described by Featherstone, et al.29 (1986)]
Ref: White and Featherstone113 (1987)
Method 1	Human sound and bovine carious enamel	Method 1:	F dentifrice is very effective in inhibiting lesion formation in initially sound enamel as well as in inhibiting lesion progression .
pH cycling sound human enamel:		CSH	The effect of F dentifrice on prevention of demineralization and increase of remineralization depends on the type of lesion
De: 6h/day (75mM acetic acid, 2mM Ca(NO3)2, 2mM KH2PO4, pH 4.3, 20 mL/sample)		Method 2:
Re: 17 h/day (20 mM cacodylate buffer at pH 7.0, 130 mM KCl, 1.5 mM Ca(NO3)2, 0.9 mM KH2PO4, 20 mL/ sample). Total:15 d (remineralizing solution, 37ºC, on the weekend)		F analysis after acid etch biopsy (samples) and Ca loss and uptake (solutions) by AAS
F treatment: slurry 1:3 water, 5 mL/ 5 min, under agitation before or after De.
Artificial caries before Method 2
(7 d, 10 mL, 37ºC): calcium-phosphate-fluoride-acetate system (2.2 mM Ca(NO3)2, 2.2 mM KH2PO4, 0.5 mM F, 50 mM acetate, pH 4.5) or 0.2 mM MHDP in 100 mM lactate buffer (pH 4.5)
Method 2
pH cycling carious bovine enamel:
De: 4 weeks -3 h/day (50 mM acetic acid, 1.5 mM Ca(NO3)2, 0.9 mM KH2PO4, pH 4.5-4.75)
Re: 21 h/day (20 mM cacodylate buffer at pH 7.0, 130 mM KCl, 1.5 mM Ca(NO3)2, 0.9 mM KH2PO4, 20 mL/ sample)
F treatment: as described above
Ref: Ten Cate, et al.93 (1988)
Test 1: 5 min test solution (2 mL), 1 min water (2 mL)	Bovine enamel with salivary pellicle	Calcium analysis by AAS (De-Re solutions)	Residual salivary [F] by water fluoridation or toothpaste may give some protection to enamel demineralization
De: 1 h acid treatment (50 mM acetic acid, 1.5 mM KH2PO4, pH 5)	(5-10mm2)
Re: 1 h remineralization (20 mM cacodylic acid, 1.5 mM KH2PO4, pH 7).
Total: 8 cycles (18 h)
Test 2: Re solution (1 h/overnight), water rinse (1 min) and acid solution (1 h) during 3 days
Ref: Page69 (1991)
Artificial caries: 8% methylcelulose gel, 0.1 M lactic acid (pH 4.6/7 d -Enamel and pH4.8/5 d-dentin)	Bovine	Calcium uptake and loss by AAS (De and Re solutions)/ TMR and loosely and firmly bound F (samples)	Low F levels - less effective to inhibit caries lesion in dentin than in enamel
pH cycling:	enamel and		F dentifrice has a more pronounced effect on dentin than on enamel
De:(3 mL, 1.5 mM CaCl2, 0.9 mM KH2PO4and 50 mM acetic acid, pH 5.0, 6x0.5 h/day)2	dentin
Re: (3 mL, 1.5 mM CaCl2, 0.9 mM KH2PO4, 130 mM KCl and 20 mM Hepes, pH 7.0, 6x 2.5 h/day, overnight and weekend)	(22 mm2)
3 days without treatment/ 7 days with treatment
Treatment: dentifrice slurry (1:3 in water, 5 min) x 3 |jM F in de-remineralizing solutions x deionized water (5 min)
Ref: Ten Cate, et al.86 (1995)
Caries lesion: 96 h De solution	Primary enamel		The 10-day pH cycling model is inappropriate for primary teeth de/remineralization analysis.
pH-cycling:	(1-mm)		Positive regarding the treatment
De: 2.2 mM CaCl2, 2.2 mM NaH2PO4, 0.05 M acetic acid, pH 4.4 . 2x3 h/day
Re:1.5 mM CaCl2, 0.9 mM NaH2PO4, 0.15 M KCl ,pH 7.0, 2 h between De, according to Ten Cate and Duijsters87 (1982)
Treatment: slurry (30 mL deionized water) for 1min before 1st De and before and after 2 ndDe		TMR and PLM
Model I: 10-day pH-cycling
Model II: 7-day pH-cycling
Ref: Thaveesangpanich, et al.95 (2005)
Caries lesion: 96 h De solution	Primary enamel		Positive results regarding the treatment.
pH-cycling:	(1-mm window)		Both 10-day (containing 0.25ppm F) and 7-day (without F) pH-cycling models were suitable for studying caries lesion progression in primary teeth
De: 2.2 mM CaCl2, 2.2 mM NaH2PO4, 0.05M acetic acid, pH 4.4 . 2x3 h/day		TMR and PLM
Re:1.5 mM CaCl2, 0.9 mM NaH2PO4, 0.15 M KCl, pH 7.0, 2 h between DE, according to Ten Cate and Duijsters87 (1982)
Treatment: slurry (30 ml deionized water) for 1 min before 1 stDe and before and after 2 ndDe
Model I: as mentioned above, 7-day pH-cycling
Model II: 0.25 ppm F added to de- and re- solutions, pH of de solution adjusted to 4.5, 10-day pH-cycling
Ref: Thaveesangpanich, et al.94 (2005)
Artificial caries: 8 % methyl cellulose gel, 0.1 M lactate buffer, pH 4.6, 7 d and 28 d, for shallow (50 |jm) and deep (200 |jm) lesions, respectively	Bovine enamel (22mm2)	Ca loss and uptake (de-re solutions) , TMR (samples)	Dose-response was shown for Ca loss but not for Ca uptake. Significant difference was found for F response between shallow and deep lesions
pH cycling: (6x3 h/day):
Re: (2.0 or 2.5 h and overnight, weekend, 1.5 mM CaCl2, 0.9 mM KH2PO4, 130 mM KCl, 20 mM Hepes, pH 7.0, 3 mL), rinse,
De: (0.5 or 1h, 1.5 mM CaCl2, 0.9 mM KH2PO4, 50 mM acetic acid, pH 4.6-4.8, 3 ml) and rinse (1.5 mM CaCl2, 0.9 mM KH2PO4, 130 mM KCl, pH 7.0 unbuffered). The solutions were changed daily.
pH cycling without treatment: 3 days
Treatment: once/ day (moderate challenges) or twice/day (severe challenges) - 5 mL slurry (1:3 in water, 1x5 min or 2x/2 min)
A robot was used for pH-cycling
Ref: Ten Cate, et al.88 (2006)
pH-cycling (7 d at 37°C):	Bovine enamel (4x4 mm)	S M H and CSH (samples) and Ca, P and F analysis (pH-cycling solutions)	The 550 ppm F acidified dentifrice had the same anticariogenic action as the 1,100 ppm F neutral formulation.
De: (2 mM Ca, 2 mM P, 0.04 ppm F, 75 mM acetate buffer, pH 4.7, 2.2 mL/mm2) for 6 h
Re: (1.5 mM Ca, 0.9 mM P, 150 mM KCl, 0.05 ppm F, 0.1 M cacodylate buffer, pH 7.0, 1.1 mL/mm2) for 18 h
Treatment: 1-min soak in slurries (1:3 water) between solution changes (twice a day). Last 2 days only in Re. According to Vieira, et al.103 (2005)
Ref: Brighenti, et al.11 (2006)
pH-cycling (7 d at 37°C):	Bovine enamel (4x4mm)	S M H, CSH, and analysis of F, Ca and P in enamel (microdrill biopsy technique)	The acidic dentifrices with 412 and 550 ppm F had the same efficacy as the neutral 1,100 ppm F dentifrice and commercial 1,100 ppm F dentifrice.
De: (2 mM Ca, 2 mM P, 0.04 ppm F, 75 mM acetate buffer, pH 4.7, 2.2 mL/mm2) for 6 h
Re: (1.5 mM Ca, 0.9 mM P, 150 mM KCl, 0.05 ppm F, 0.1 M cacodylate buffer, pH 7.0, 1.1 mL/mm2) for 18 h
Treatment: 1-min soak in slurries (1:3 water) between solution changes (twice a day). Last 2 days only in Re. According to Vieira et al.103 (2005)
Ref: Alves, et al.3 (2007)
Artificial caries (for re only): 0.05 M acetate buffer, pH 5.0 containing 1.28 mM Ca, 0.74 mM P, 0.03 ppm F, 2 mL/mm2for 32 h	Bovine enamel (4x4x3 mm)	SMH, CSH, PLM	The low-F dentifrice presented anticaries potential, but it was not equivalent to the dentifrices containing 1,100 ppm F
De pH-cycling (8 d, 37°C):			Both de and remineralizing models seem to be adequate to evaluate the anticaries potential of low-F dentifrice
De: 0.05 M acetate buffer, pH 5.0 containing 1.28 mM Ca, 0.74 mM P, 0.03 ppm F- 4 h/day, 6.25 mL/mm2
Re: 1.5 mM Ca, 0.9 mM P, 150 mM KCl, 0.05 ppm F in 0.1 M Tris, pH 7.0 20 h/day, 3.12 mL/mm2
Treatment: (before and after immersion in de): F solutions (0, 70, 140, 280 ppm F, NaF) or slurries (1:3) of dentifrices containing 0, 500 ppm F, 1,100 ppm F or Crest (1,100 ppm F - Gold standard) all NaF, for 5 min under agitation
After the 8thcycle remained in Refor 24 h
Re pH-cycling: same as De, but 2 h in De and 22 h in Re, 3 treatments of 1 min/day
Ref: Queiroz, et al.75 (2008)