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 β5, tropomyosin, β-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.

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.

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.

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 &lt; .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 &lt; .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 &lt; .001) and CPP-ACPFV groups (P &lt; .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.

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. 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. K E Y W O R D Sacid etching, caries detection, enamel demineralization, light-induced fluorescence, white spot lesion