. 2010 Jul-Aug;18(4):316–334. doi: 10.1590/S1678-77572010000400002

Figura 5.

pH-cycling studies comparing the impact of new active principles on the anti-caries efficacy of fluoride dentifrices

PROTOCOL	DENTAL TISSUE	RESPONSE VARIABLE	CONCLUSION
pH-cycling (14 d, 37°C):	Human enamel	CSH	Inclusion of pyrophosphate in NaF dentifrice did not affect the net outcome of the cycling De/Re
De: 6 h/day (2 mM Ca, 2 mM PO₄, 0.075 mM acetate, pH 4.3, 40 mL/sample)
Treatment: 5 min dentifrice slurry 1:3 water (4 mL/sample, under agitation), water rinse
Re: 17 h (1.5 mM Ca, 0.9 mM PO₄, 150 mM KCl, cacodylate buffer pH 7, 20 mL/sample). Solutions were changed each 7d. On the weekends, there was only remineralization. According to Featherstone et al.²⁹ (1986)
Ref: Featherstone, et al.³⁰ (1988)
pH-cycling (6x3 h/day):	Bovine enamel	Ca uptake and loss (solutions)	The addition of triclosan and zinc citrate does not affect the caries-preventing property of F dentifrice
Re: (2.5 h and overnight, weekend, 1.5 mM CaCl₂, 0.9 mM KH₂PO₄, 130 mM KCl, 20 mM cacodylate buffer, pH 7.0, 3 mL)
De: (0.5 h, 1.5 mM CaCl₂, 0.9 mM KH₂PO₄, 50 mM acetic acid, pH 5, 3 mL), according to Ten Cate and Duijsters⁸⁷ (1982) with slight modifications.
Treatment: 1 min daily in slurry (1:3 in water) followed by water rinse
A pH-cycling robot was used to change the solutions
pH cycling without treatment: 3 days
pH cycling with treatment: 14 days
Ref: Ten Cate⁸⁴ (1993)
pH-cycling: dentifrices were applied to sound enamel windows for 3 min at 8-h intervals for 14 d.	Human enamel	PLM (lesion depth)	The addition of ACaPO4 to a fluoride dentifrice resulted in a trend toward further reductions in lesion depth following in vitrolesion formation and progression over those obtained with a fluoride dentifrice.
Dentifrices were removed, enamel rinsed for 3 min with deionized water and placed in artificial saliva (20 mM NaHCO₃, 3 mM NaH₂PO₄, 1 mM CaCl₂, pH 7.0), rinsed with deinized water for 3 min.
Artificial caries: enamel lesions were created with an acidified gel (1 mM Ca, 0.6 mM PO₄, 0.1 mM F, pH 4.25) and evaluated by PLM.
Treatment: enamel with caries-like lesions were treated again for 14 d as described above, returned to acidified gels for progression of the lesions and sections for PLM were obtained again. This was repeated once more.
Ref: Hicks and Flaitz³⁹ (2000)
Artificial caries: 13 mL of 0.1 M lactic acid, 0.2% poliacrilic acid (Carbopol C907), 50% saturated hydroxyapatite, pH 5.0 for 72 h, according to White¹¹⁰ (1987).	Human enamel	SMH	The new dentifrice with ion-exchange resin (calcium, phosphate, fluoride and zinc) has the same effect than the conventional dentifrice in de/remineralisation
Treatment: 1 min, 10 mL slurry 1:3 in human saliva, 4 x/day	(0.6 cm diameter)
Re: 15 mL natural saliva, 37°C, 1 h, under agitation
De: 3 h in the same solution for producing artificial caries
Total: 16 days (except weekends)
Ref: Torrado, et al.¹⁰² (2004)
Artificial caries: 0.2% carbopol C907, 0.1 M lactic acid 50% saturated with calcium phosphate, pH 5.0 for 44 h	Bovine enamel	S M H /p H of demineralizing solutions after the third dentifrice treatment	Dentifrice containing both F and sanguinaria was more effective than dentifrice containing F alone on remineralization of enamel lesion and on the pH of de solution. NaF dentifrices were more effective than MFP dentifrices.
Preparation: specimens placed in natural saliva for 24 h for pellicle formation/salivary mineral salts KCl, K₂HPO₄, NaCl, MgCl₂and CaCl₂were added to TSB containing 10% sucrose/Specimens were placed in 20 mL of TSB De-Re solution containing 2 mL of S. sobrinus (B13) cultured for 24 h/Culture for 24 h (twice)	(3 mm diameter)
pH-cycling (15 days): 2 min in slurry (1:2 saliva), 2 h Re (50% stimulated human saliva and 50% artificial saliva), 2 h De (TSB with mineral salts and sucrose). This was repeated 3 times, but in the last time Re lasted 6 h and De 10 h
Ref: Hong, et al.⁴⁰ (2005)
pH-cycling (14 days, 37ºC):	Human enamel (4x4 mm)	SMH	The whitening toothpastes evaluated showed effect similar to regular, nonwhitening toothpastes.
De: 6 h/day (24 ml, 2 mM Ca, 2 mM PO₄, 0.075 M acetate, pH 4.3)
Treatment: dentifrice slurry 1:3 in water, 5 ml 10 min
Re: 17 h/day and overnight/ on the weekends (24 ml, 1.5 mM Ca, 0.9 mM PO₄, 0.15 mM KCl, 20 mM HEPES buffer, pH 7.0) according to Featherstone et al.²⁹ (1986)
Ref: Watanabe, et al.¹⁰⁵ (2005)

Artificial caries: 2.2 mM CaCl₂, 2.2 mM KH₂PO₄, 0.05 M acetic acid, pH 4.4, 96 h, 10 ml, 150-200 pm deep	Human enamel	PLM and TMR	Both test Asiatic dentifrices remineralized initial carious lesions. However, the remineralizing potential of Colgate Total was higher.
pH-cycling (10 d):
Treatment : slurry (1:3), 5 ml, 1 min
De: same as artificial caries, 10 ml, 3 h
Re: 1.5 mM CaCl₂, 0.9 mM NaH₂PO₄, 0.15 M KCl, pH 7.0, for 2 h
Treatment: slurry (1:3), 5 ml, 1 min/demineralization solution 3 h/treatment with slurry (1:3), 5 ml 1 min/remineralizing solution overnight
Ref: Rana, et al.⁷⁶ (2007)
Artificial caries (for Re only): 1:1 8% methyl cellulose/acid lactic gel system at 37°C, pH 4.6 for 10 days	Bovine enamel	Analysis of total Ca in acidic buffer with the electrode for De and % SMH change for Re	In de and remineralization studies, the silica based blue covarine whitening dentifrice was similar to the conventional dentifrice.
Re pH-cycling (6 x/day for 8 days. Neutral buffer overnight/ weekend)
Treatment: slurry (1:3) for 5 min
De: acidic buffer (1.5 mM CaCl₂.2H₂O, 0.9 mM KH₂PO₄, 130 mM KCl, 50 mM acetic acid, pH 5.0) for 30 min/neutral buffer (1.5 mM CaCl₂.2H2O, 0.9 mM KH₂PO₄, 130 mM KCl, 20 mM HEPES ) for 10 min based on Gibbs et al.³⁴ (1995)
De pH-cycling (12 times, 2ml each solution): slurry (1:3) for 5 min/ acidic buffer (1.5 mM KH₂PO₄, 50 mM acetic acid, pH 5.0) for 60 min/neutral buffer (1.5 mM K H₂PO₄, 20 mM HEPES, pH 7.0) for 1 min based on Page⁶⁹ (1991)
Ref: Joiner, et al. ⁴⁵ (2008)