Browsing by Subject "pH cycling"

Now showing 1 - 3 of 3
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    Effects of fluoride concentration and temperature of milk on caries lesion rehardening
    (Elsevier, 2012-10) Lippert, Frank; Martinez-Mier, Esperanza A.; Soto-Rojas, Armando E.; Department of Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    Objectives The aim of the present in vitro study was to investigate the effects of fluoride concentration and temperature of milk on caries lesion rehardening under pH cycling conditions. Methods Incipient caries-like lesions were formed in human enamel specimens, characterized using Vickers surface microhardness (VHN) and assigned to seven treatment groups (n = 18 per group): fluoride was tested at five levels (0, 2.5, 5, 10, 20 mg/l, all 22 °C) and milk temperature at three levels (4, 22, 60 °C), but only for 10 mg/l F. Lesions were pH cycled for 15d (4×/daily 10 min milk treatments, 1×/daily 4 h acid challenge, remineralization in human/artificial saliva mixture). VHN of specimens were measured again and changes from lesion baseline were calculated. Subsequently, enamel fluoride uptake (EFU) was determined using the micro drill technique. Results Lesions responded to fluoride in a dose–response manner with higher fluoride concentrations resulting in more lesion rehardening (20 > 10 ≥ 5 ≥ 2.5 > 0 mg/l F). Furthermore, fluoridated milk at 60 °C was found to be more efficacious than at 4 °C (60 ≥ 22 > 4 °C). EFU results were similar (20 > 10 > 5 > 2.5 ≥ 0 mg/l F; 60 > 22 ≥ 4 °C). Conclusions Both fluoride concentration and milk temperature are likely to contribute to the anti-caries potential of fluoridated milk.
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    Fluoride Dose-Response of Human and Bovine Enamel Artificial Caries Lesions under pH-Cycling Conditions
    (Springer, 2015-11) Lippert, Frank; Juthani, Kalp; Department of Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    Objectives This laboratory study aimed to (a) compare the fluoride dose-response of different caries lesions created in human and bovine enamel (HE/BE) under pH-cycling conditions and (b) investigate the suitability of Knoop and Vickers surface microhardness (K-SMH/V-SMH) in comparison to transverse microradiography (TMR) to investigate lesion de- and remineralization. Materials and methods Caries lesions were formed using three different protocols (Carbopol, hydroxyethylcellulose-HEC, methylcellulose-MeC) and assigned to 24 groups using V-SMH, based on a 2 (enamel types) × 3 (lesion types) × 4 (fluoride concentrations used during pH-cycling-simulating 0/250/1100/2800 ppm F as sodium fluoride dentifrices) factorial design. Changes in mineral content and structural integrity of lesions were determined before and after pH-cycling. Data were analyzed using three-way ANOVA. Results BE was more prone to demineralization than HE. Both enamel types showed similar responses to fluoride with BE showing more remineralization (as change in integrated mineral loss and lesion depth reduction), although differences between tissues were already present at lesion baseline. Carbopol and MeC lesions responded well to fluoride, whereas HEC lesions were almost inert. K- and V-SMH correlated well with each other and with the integrated mineral loss data, although better correlations were found for HE than for BE and for MeC than for Carbopol lesions. Hardness data for HEC lesions correlated only with surface zone mineral density data. Conclusion BE is a suitable surrogate for HE under pH-cycling conditions. Clinical relevance The in vitro modeling of dental caries is complex and requires knowledge of lesion behavior, analytical techniques, and employed hard tissues.
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    The effect of silver diamine fluoride on the remineralization of early enamel carious lesions under pH-cycling conditions
    (Elsevier, 2022) Sorkhdini, Parand; Crystal, Yasmi O.; Tang, Qing; Lippert, Frank; Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    Background This study explored the in vitro anticaries efficacy of silver diamine fluoride (SDF) in remineralizing early enamel carious lesions. Methods Lesions were created in human enamel specimens, which were divided into 5 groups (n = 36): SDF (38%), SDF and potassium iodide (SDF and KI), potassium fluoride (KF), silver nitrate (AgNO3), and deionized water (DIW). Treatments were applied once. Groups were divided into 2 subgroups (n = 18), pH cycled for 5 days with twice-daily treatments with either fluoride or DIW. Vickers hardness number measurements were conducted at each stage. Data were analyzed using a 2-way analysis of variance. Results The 2-way analysis of variance for ΔVickers hardness number was significant (P < .0001). In both pH-cycling models (with or without fluoride), SDF, SDF and KI, and KF promoted more remineralization than AgNO3 and DIW (P < .0001). In the presence of twice-daily fluoride treatments, there was no difference between SDF, SDF and KI, and KF (P = .4577). However, in the absence of fluoride treatments, SDF promoted more remineralization than SDF and KI and KF (P < .0001). There were no differences between SDF and KI and KF (P = .4577 and P = .2156; pH-cycling models with and without fluoride, respectively) and AgNO3 vs DIW (P = .6553 and P = .1194). Conclusion With the copresence of fluoride, SDF and SDF and KI equally promote remineralization of enamel lesions. KI impairs SDF-related remineralization in the absence of fluoride treatments.