Despite a plethora of in situ studies and clinical trials evaluating
the efficacy of fluoridated dentifrices on caries control, in vitro
pH cycling models are still broadly used because they mimic the dynamics of mineral
loss and gain involved in caries formation. This paper critically reviews the current
literature on existing pH-cycling models for the in vitro
evaluation of the efficacy of fluoridated dentifrices for caries control, focusing on
their strengths and limitations. A search was undertaken in the MEDLINE electronic
journal database using the keywords "pH-cycling", "demineralization",
"remineralization", "in vitro", "fluoride", "dentifrice". The
primary outcome was the decrease of demineralization or the increase of
remineralization as measured by different methods (e.g.: transverse microradiography)
or tooth fluoride uptake. Inclusion of studies, data extraction and quality
assessment were undertaken independently and in duplicate by two members of the
review team. Disagreements were solved by discussion and consensus or by a third
party. One hundred and sixteen studies were included, of which 42 addressed
specifically the comparison of dentifrices using different pH-cycling models. The
other studies included meta-analysis or reviews, data about the effect of different
fluoride sources on de-remineralization, different methods for analysis
de-remineralization and chemical variables and characteristics of dental hard tissues
that might have influence on de-remineralization processes. Generally, the studies
presented ability to detect known results established by clinical trials, to
demonstrate dose-related responses in the fluoride content of the dentifrices, and to
provide repeatability and reproducibility between tests. In order to accomplish these
features satisfactorily, it is mandatory to take into account the type of substrate
and baseline artificial lesion, as well as the adequate response variables and
statistical approaches to be used. This critical review of literature showed that the
currently available pH-cycling models are appropriate to detect dose-response and
pH-response of fluoride dentifrices, and to evaluate the impact of new active
principles on the effect of fluoridated dentifrices, as well as their association
with other anti-caries treatments.
This study analyzed degrees of demineralization in bovine enamel using synchrotron microcomputed tomography (SMCT) and hardness measurements (Knoop hardness number, KHN). For 5 days, 40 bovine enamel blocks were individually subjected to a pH cycling model and treatment with fluoride dentifrices (placebo, 275, 550 and 1,100 μg F/g) diluted in deionized water twice a day. Surface hardness number and cross-sectional profiles of hardness and mineral concentration (by SMCT) were determined. Integrated hardness (KHN × μm) for sound and demineralized specimens was calculated and subtracted to give the integrated loss of hardness (ΔKHN) for the lesions. Increasing fluoride concentration in the dentifrices led to higher values for surface hardness after pH cycling and mineral concentration (gHAp cm–3), and lower values for ΔKHN (p < 0.05). From the present results, it may be concluded that hardness measurements revealed demineralization in all groups, which was lower in groups treated with dentifrice with a higher F concentration. SMCT and hardness measurements gave similar results in areas with higher demineralization, but diverged in areas with lower demineralization.
This double-blind crossover in situ study evaluated the effect of rinsing with water immediately after the application of acidulated phosphate fluoride (APF) on enamel demineralization. APF application was followed by: no rinsing or consuming of liquids or solids for the next 30 min; immediately washing with water jet or drinking of a glass of water. All treatments showed a statistically significant decrease in enamel mineral loss compared to the control (p < 0.05), but the differences among treatments were not significant (p > 0.05). The data suggest that the recommendation of asking patients to refrain from drinking water following professional APF application does not seem to have an influence on the anticaries effect of fluoride.
Because of the growing concerns regarding fluoride ingestion by young children and
dental fluorosis, it is necessary to develop new dentifrices.ObjectiveThe aim of this study was to evaluate the effect of dentifrices with calcium
citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel demineralization. Material and MethodsEnamel blocks (n=70), previously selected through surface hardness analysis, were
submitted to daily treatment with dentifrices diluted in artificial saliva and to
a pH-cycling model. The fluoride concentration in dentifrices was 0, 250, 450,
550, 1,000 and 1,100 µg F/g. CrestTM was used as a positive control
(1,100 mg F/g). Cacit (0.25%) and TMP (0.25%) were added to dentifrices with 450
and 1,000 µg F/g. Surface hardness was measured again and integrated loss of
subsurface hardness and fluoride concentration in enamel were calculated.
Parametric and correlation tests were used to determine difference (p<0.05) and
dose-response relationship between treatments. ResultsThe addition of Cacit and TMP did not provide a higher fluoride concentration in
enamel, however it reduced (p<0.05) mineral loss when compared to other
dentifrices; the dentifrice with Cacit and TMP and a low fluoride concentration
presented similar results when compared to a dentifrice with 1,100 mg F/g
(p>0.05). ConclusionsDentifrices with 450 and 1,000 µg F/g, Cacit and TMP were as effective as a gold
standard one.
The aim of this study was to compare the effect of topical fluoride products [acidulated phosphate fluoride (APF) or neutral gel (NF) x fluoride toothpaste (MFP)], in respect to fluoride uptake and anticariogenic action. One hundred and twenty five blocks of human teeth, sorted in 5 groups according to the treatment, were submitted to pH cycling for ten days. The parameters analyzed were: fluoride uptake before and after pH cycling and surface (SMH) and cross-sectional (CSMH) microhardness of the enamel blocks. The results of fluoride concentration in enamel after the pH cycling showed an enhancement of fluoride uptake for all groups compared to sound control. No significant differences between APF and MFP were observed for surface microhardness, percentage change of surface microhardness and mineral loss. The volume percent mineral obtained from cross-sectional microhardness demonstrated that APF has a different lesion progression rate regarding subsurface carious lesion. The results suggest that professionally applied fluoride gel or frequent fluoride application in low concentration is a positive preventive measure for the control of dental caries.
Peripheral cement-ossifying fibroma is a relatively common gingival growth of a reactive rather than neoplastic nature, whose pathogenesis is uncertain. It predominantly affects adolescents and young adults, with peak prevalence between 10 and 19 years. We report here the clinical case of a 5-year-old girl with disease duration of 3 years, who was followed up for 4 years, showing a gingival health and normal radiopacity of bone.
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