Efficacy of CPP-ACP fluoride varnish applied with and without acid etching in preventing enamel demineralization compared to light-curable fluoride varnish.

OBJECTIVES: To compare efficacy of casein phosphopeptide (CPP)-amorphous calcium phosphate (ACP) fluoride varnish and light-curable resin modified glass ionomer fluoride varnish (FV) in preventing white spot lesions and evaluating acid etching prior to CPP-ACPFV application on its efficacy. MATERIALS AND METHODS: Molars and premolars were transected and halves divided into four groups (n = 18/group): (1) resin-modified glass ionomer FV: etched and Clinpro-XT varnish (3M ESPE, Pymble, New South Wales, Australia) application; (2) CPP-ACPFV: MI varnish (GC America, Alsip, IL) application; (3) Etch+CPP-ACPFV: etched and MI varnish application; (4) Control: etched and no surface treatment. To simulate 12 weeks in an intraoral environment, samples were subjected to thermocycling, brushing, and pH cycling. Enamel surface microhardness was evaluated at baseline and after the simulated 12 weeks. Representative samples were also assessed using scanning electron microscopy (SEM). RESULTS: At baseline there was no significant difference in microhardness among groups. After the simulated 12 weeks, all groups showed significant within-group differences (P < .001). Control showed the highest percentage loss of surface microhardness (89%), followed by CPP-ACPFV (58%), RMGIFV (51%), and Etch+CPP-ACPFV (24%). The control group had a significant decrease in microhardness compared to all experimental groups (P < .001). No difference was found between the RMGIFV and CPP-ACPFV varnish groups. The Etch+CPP-ACPFV group had significantly less decrease in microhardness compared to the RMGIFV (P < .001) and CPP-ACPFV groups (P < .001). With SEM, control samples showed signs of enamel surface damage, while experimental groups showed spherical particles on a relatively intact surface. CONCLUSIONS: RMGIFV and CPP-ACPFV are effective in reducing enamel demineralization. Acid etching the enamel surface prior to CPP-ACPFV varnish application increased its efficacy.

How different time intervals between repeated applications of CPP-ACP fluoride varnish effect smooth surface enamel demineralization?

OBJECTIVES: To evaluate the preventive effects of different time intervals between repeated applications of the CPP-ACP fluoride varnish on enamel demineralization. METHODS: Human teeth were sectioned and randomly allocated to three groups: 4-week, 6-week, and 12-week (N = 22/group). Baseline images of the enamel surfaces were obtained using the FluoreCam recording the area, intensity, and impact of baseline enamel demineralization. All groups received fluoride varnish applications at the beginning of the experiment. The varnish was reapplied every 4 or 6 weeks in the 4-week and 6-week groups, respectively. Following each application, the groups underwent thermo-cycling, tooth brushing and pH cycling to simulate the time effect. After 12 weeks, the enamel surfaces were reimaged using the FluoreCam. Within and between-group differences in the area, intensity and impact of demineralization were evaluated. RESULTS: At baseline, there were no significant between-group differences for area, intensity, or impact. Statistically significant (p<0.001) enamel demineralization occurred over time within each group. There were significant between-group differences in the changes that occurred in area (P = 0.004), impact (P = 0.022), but not intensity. The 12-week had significantly larger areas of demineralization than the 6-week (P = 0.041) and 4-week (P = 0.001) groups. Changes in impact was significantly (P = 0.007) greater in the 12-week group than 4-week group, but not greater than the 6-week group. There were no statistically significant differences between 4- and 6-week groups in the changes of area, intensity, or impact. CONCLUSION: Reapplication of the CPP-ACP fluoride varnish every 4-6 weeks, is more effective in reducing enamel demineralization compared to every 12 weeks.

Preventive effects of carbon dioxide laser and casein phosphopeptide amorphous calcium phosphate fluoride varnish on enamel demineralization: A comparative, in vitro study.

AIM: The aim of the present study was to compare the effects of carbon dioxide (CO2 ) laser and casein phosphopeptide amorphous calcium phosphate (CPP-ACP)fluoride varnish on enamel demineralization. METHODS: Human teeth were randomly assigned to three groups. The enamel was treated with fluoride varnish, 10.6 µm CO2 laser, or no treatment (control), followed by 9 days of pH cycling. Baseline and final FluoreCam images were used to quantify the area, intensity, and impact of demineralization; cross-sectional microhardness was used to measure the mechanical properties of the enamel. RESULTS: There were statistically-significant changes in the area, intensity and impact of demineralization in the control and laser groups (P < 0.05), but not in the fluoride group. The control group showed a significantly greater area and impact of enamel demineralization compared to the fluoride group. The area of demineralization in the laser group was significantly greater than that of the fluoride group. Enamel demineralization of the laser and control groups was comparable. The fluoride group showed statistically-significant harder enamel than the control at 20, 40, and 60 µm depths; the laser group enamel was significantly harder than the control at 20 and 40 µm depths. The fluoride group showed statistically-significant harder enamel than the laser group at 20 µm depth. CONCLUSIONS: CPP-ACP fluoride varnish is more effective than CO2 in preventing enamel demineralization.

The longevity of casein phosphopeptide-amorphous calcium phosphate fluoride varnish's preventative effects: Assessment of white spot lesion formation.

OBJECTIVES: To test how long casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) fluoride varnish prevents enamel demineralization in vitro. MATERIALS AND METHODS: Human molars and premolars were sectioned buccolingually and randomly assigned to two groups. Standardized pretreatment images of enamel surfaces were obtained using FluoreCam. The control group received no treatment, and the experimental group received an application of CPP-ACP fluoride varnish. Over simulated periods of 2, 4, 8, and 12 weeks, specimens were placed in a toothbrushing simulator, thermocycled, subjected to 9 days of pH cycling, and imaged with FluoreCam. Samples were sectioned and polished for polarized light microscope (PLM) evaluation. RESULTS: There were statistically significant time ( P < .001) and varnish ( P < .001) effects on area, intensity, and impact of enamel demineralization. The control group showed significant and progressive demineralization over the 12 weeks ( P < .001). The experimental group revealed no significant demineralization during the first 4 weeks ( P > .05) and significant ( P < .001) increases thereafter. Experimental demineralization after 12 weeks was comparable to 2-week demineralization in the controls, with significant between-group differences ( P < .001) in enamel demineralization at all time points. PLM of the control and experimental groups revealed lesion depths of 90 ± 34 µm and 37 ± 9 µm, respectively. CONCLUSIONS: Within the limitations of this in vitro study, CPP-ACP fluoride varnish prevents enamel demineralization for at least 4 weeks and limits demineralization up to 12 weeks.

White spot lesions: Does etching really matter?

AIM: The clinical significance of acid etching prior to orthodontic bonding is controversial. In the present study, we evaluated the effect of 15 seconds of acid etching on enamel demineralization. METHODS: Twenty-seven human molars were sectioned and assigned to two groups. Under standardized conditions, the enamel surfaces were imaged using FluoreCam to obtain baseline data. Group 1 was etched using 37% phosphoric acid for 15 seconds, rinsed with water, and then imaged again; group 2 was only rinsed with water. Water rinse was collected for calcium chemical analysis using inductively-coupled plasma auger electron spectrometry. Both groups were subjected to 9 days of pH cycling, after which final FluoreCam images were obtained. RESULTS: Group 1 showed a significant increase in lesion area (P=.012), decrease in light intensity (P=.009), and decrease in impact (P=.007) after acid etching. The amount of calcium that leached out over the 15 seconds was 14 ppm ±2.4 (0.35 mmol/L±0.06). Following pH cycling, there was no statistically-significant between-group difference in overall enamel demineralization. CONCLUSION: Initial demineralization caused by 15 seconds of acid etching does not increase enamel susceptibility to further demineralization. This suggests that acid etching does not increase the risk of developing white spot lesions during orthodontics.

Reliability and validity of FluoreCam for white-spot lesion detection: An in vitro study.

AIM: In the present study, we tested the reliability and validity of a new light fluorescence device, the FluoreCam. METHODS: Twenty-five human teeth were sectioned mesiodistally into halves. Group 1 (n=30) included specimens with either sound enamel or natural white-spot lesions (WSL). Group 2 (n=20) included specimens with sound enamel used to create artificial WSL. Using the FluoreCam, baseline scans of enamel surfaces were obtained under standardized conditions. Group1 was scanned again the next day. Group 2 specimens were covered with an acid-resistant nail polish, leaving a 2 × 6-mm enamel window exposed, immersed in Queiroz-solution (64 hours, 37°C/pH5 with agitation), and then scanned again. Random error of the repeated measurements (reliability) was determined using method errors and intraclass correlations (ICC). Systematic error and the ability to detect demineralization (validity) were tested using Wilcoxon signed-rank test. RESULTS: Method errors for Group 1 replicates were .39 mm2 (area), .72 pixels (intensity), and 5.69 pixels.mm2 (impact). Group 2 method errors were consistently slightly higher than those of group 1. FluoreCam showed highly reliable measurements for group 1 (ICC: 0.93-0.98) and group 2 (ICC: 0.87-0.97). There were no statistically-significant systematic errors for either group (P>.05). In group 2, enamel demineralization was statistically significant in area (P<.001), intensity (P=.001), and impact (P<.001). CONCLUSION: FluoreCam is highly reliable and valid for in vitro assessments of enamel demineralization.

Comparative study of two chemical protocols for creating white spot lesions: An in vitro FluoreCam evaluation.

AIM: The aim of the present study was to compare the effectiveness and practicality of two commonly-used protocols for white spot lesion creation. METHODS: Sound posterior human teeth were sectioned into halves and randomly allocated into two groups (n=20). Using the FluoreCam system, the enamel surfaces were imaged under standardized conditions, and baseline data (area, intensity, and impact) were recorded. Specimens were covered with an acid-resistant polish, leaving a 2×6-mm enamel window. Group 1 was immersed in Queiroz solution (64 hours/37°C/pH5 with agitation); Group 2 was immersed in Buskes solution (14 days/37°C/pH5 with agitation). The specimens then were imaged again. Within-group changes that occurred over time were evaluated using the Wilcoxon signed-rank test. Between-group differences were analyzed using the Mann-Whitney U-test. Polarized light microscopy (PLM) was used to calculate the mean lesion depth of representative specimens. RESULTS: Each protocol showed significant changes in the surface area, intensity and impact of demineralization over time (P<.05). There were no statistically-significant differences (P=.53, P=.2, P=.74) between the two groups. PLM showed that the mean lesion depths of representative specimens were 51.4 and 73.0 µm for groups 1 and 2, respectively. CONCLUSIONS: While both protocols produce similar amounts of demineralization, the Queiroz solution is more practical, as it requires less time.

Integrative Temporo-Spatial, Mineralogic, Spectroscopic, and Proteomic Analysis of Postnatal Enamel Development in Teeth with Limited Growth.

Tooth amelogenesis is a complex process beginning with enamel organ cell differentiation and enamel matrix secretion, transitioning through changes in ameloblast polarity, cytoskeletal, and matrix organization, that affects crucial biomineralization events such as mineral nucleation, enamel crystal growth, and enamel prism organization. Here we have harvested the enamel organ including the pliable enamel matrix of postnatal first mandibular mouse molars during the first 8 days of tooth enamel development to conduct a step-wise cross-sectional analysis of the changes in the mineral and protein phase. Mineral phase diffraction pattern analysis using single-crystal, powder sample X-ray diffraction analysis indicated conversion of calcium phosphate precursors to partially fluoride substituted hydroxyapatite from postnatal day 4 (4 dpn) onwards. Attenuated total reflectance spectra (ATR) revealed a substantial elevation in phosphate and carbonate incorporation as well as structural reconfiguration between postnatal days 6 and 8. Nanoscale liquid chromatography coupled with tandem mass spectrometry (nanoLC-MS/MS) demonstrated highest protein counts for ECM/cell surface proteins, stress/heat shock proteins, and alkaline phosphatase on postnatal day 2, high counts for ameloblast cytoskeletal proteins such as tubulin ß5, tropomyosin, ß-actin, and vimentin on postnatal day 4, and elevated levels of cofilin-1, calmodulin, and peptidyl-prolyl cis-trans isomerase on day 6. Western blot analysis of hydrophobic enamel proteins illustrated continuously increasing amelogenin levels from 1 dpn until 8 dpn, while enamelin peaked on days 1 and 2 dpn, and ameloblastin on days 1-5 dpn. In summary, these data document the substantial changes in the enamel matrix protein and mineral phase that take place during postnatal mouse molar amelogenesis from a systems biological perspective, including (i) relatively high levels of matrix protein expression during the early secretory stage on postnatal day 2, (ii) conversion of calcium phosphates to apatite, peak protein folding and stress protein counts, and increased cytoskeletal protein levels such as actin and tubulin on day 4, as well as (iii) secondary structure changes, isomerase activity, highest amelogenin levels, and peak phosphate/carbonate incorporation between postnatal days 6 and 8. Together, this study provides a baseline for a comprehensive understanding of the mineralogic and proteomic events that contribute to the complexity of mammalian tooth enamel development.