- Browse by Subject
Browsing by Subject "enamel caries"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Effect of Enamel Caries Lesion Baseline Severity on Fluoride Dose-Response(Hindawi, 2017) Lippert, Frank; Department of Cariology, Operative Dentistry and Dental Public Health, School of DentistryThis study aimed to investigate the effect of enamel caries lesion baseline severity on fluoride dose-response under pH cycling conditions. Early caries lesions were created in human enamel specimens at four different severities (8, 16, 24, and 36 h). Lesions were allocated to treatment groups (0, 83, and 367 ppm fluoride as sodium fluoride) based on Vickers surface microhardness (VHN) and pH cycled for 5 d. The cycling model comprised 3 × 1 min fluoride treatments sandwiched between 2 × 60 min demineralization challenges with specimens stored in artificial saliva in between. VHN was measured again and changes versus lesion baseline were calculated (ΔVHN). Data were analyzed using two-way ANOVA (). Increased demineralization times led to increased surface softening. The lesion severity×fluoride concentration interaction was significant (). Fluoride dose-response was observed in all groups. Lesions initially demineralized for 16 and 8 h showed similar overall rehardening (ΔVHN) and more than 24 and 36 h lesions, which were similar. The 8 h lesions showed the greatest fluoride response differential (367 versus 0 ppm F) which diminished with increasing lesion baseline severity. The extent of rehardening as a result of the 0 ppm F treatment increased with increasing lesion baseline severity, whereas it decreased for the fluoride treatments. In conclusion, lesion baseline severity impacts the extent of the fluoride dose-response.Item Effect of fluoride and abrasives on artificial enamel caries lesions(2012) Nassar, Hani M., 1979-; Hara, Anderson T.; González-Cabezas, Carlos, 1966-; Lippert, Frank; Fontana, Margherita Ruth, 1966-; Chu, Tien-Min GabrielHypothesis: The interaction between the abrasive level and fluoride concentration of dentifrice slurries modulates the surface loss (SL) and remineralization of incipient enamel caries (IEC). Methods: Three types of IEC were created and six experimental slurries with different combinations of fluoride content and abrasive level were tested. In experiment 1, the three IEC were subjected to brushing (with experimental slurries) and remineralization cycles for 5 days. Fluoride concentrations (0 and 275 ppm as NaF) and abrasive levels (Low and High) were tested. SL was determined by optical profilometry at baseline and after 1, 3, and 5 days. In experiment 2, changes in IEC mineral content (Δ(ΔZ)C) and depth (ΔLC) were investigated at baseline and after the 5-day cycling with transverse microradiography. In experiments 3 and 4, SL of MeC and CMC lesions were further studied, respectively; testing not only fluoride concentration (275 and 1250 ppm as NaF) and abrasivity (low and high) of the slurry, but also the brushing frequency (1x, 2x, and 3x/day). Brushing-remineralization cycles were performed for 7 days. Statistical analyses were performed at 5% significance level. Results: Experiment 1: overall, brushing with the high-abrasive slurry caused more SL than with the low-abrasive. For CMC and MeC lesions, 0 ppm F had more SL than 275 ppm F only after day 3. Fluoride had no effect on the SL of HEC lesions. Experiment 2: fluoride and abrasives did not have a significant effect on IEC. HEC had significantly lower Δ(ΔZ)C than CMC and MeC, with CMC and MeC not differing from each other. Lesion type had no effect on ΔLC. Experiment 3: brushing CMC lesions 3x/day with 1250 ppm F increased SL compared to 1x/day, after 5 and 7 days. Study 4: brushing MeC lesions with high abrasive slurry containing 1250 ppm F increased SL after 5 and 7 days. Conclusions: The IEC tested showed different SL and remineralization behaviors. The fluoride content and abrasive level of the toothpaste showed to be relevant modulating the SL of enamel caries lesions as well as their remineralization behavior.Item 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 DentistryObjectives 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.