Remineralization Of Enamel Subsurface Lesions Research Articles

Remineralization of enamel subsurface lesions using toothpaste containing tricalcium phosphate and fluoride: an in vitro \xb5CT analysis

BackgroundThis study aimed to compare the efficacies of experimental toothpastes containing functionalized tricalcium phosphate (fTCP) with and without fluoride for in vitro enamel remineralization under pH-cycling conditions.MethodsTo create artificial white spot lesions, 36 bovine enamel specimens were immersed in a demineralization solution for 10 days. During pH-cycling for 12 days, the specimens were divided into four groups based on the experimental toothpaste type used: (a) fTCP-free, fluoride-free (fTCP − F −); (b) fTCP-containing, fluoride-free (fTCP + F −); (c) fTCP-free, fluoride-containing (fTCP − F +); and (d) fTCP-containing, fluoride-containing (fTCP + F +). Micro-focus X-ray computed tomography (μCT) scans of all specimens were obtained before demineralization, after demineralization, and after pH-cycling. The mineral density and mineral loss (ΔZ) in the enamel subsurface lesions were measured and the percentage of remineralization (%R) was calculated from ΔZ after demineralization and pH-cycling. One-way ANOVA with Tukey’s test was used for statistical analysis of the %R values. The treated enamel surface was investigated via scanning electron microscopy (SEM).ResultsThe fTCP − F − group presented with the lowest amount of mineral gain after pH-cycling. In contrast, the fTCP + F + group showed the highest degree of remineralization within all lesion parts. The %R was highest in the fTCP + F + group (38.2 ± 7.8, all P < 0.01). SEM revealed the presence of small crystals on the enamel rods in the fTCP + F − and fTCP + F + groups.ConclusionsThe experimental toothpaste containing fTCP and fluoride increased remineralization of the artificial enamel subsurface lesions during pH-cycling. Furthermore, fTCP and fluoride appear to act independently on the remineralization of enamel subsurface lesions, although they coexisted in one toothpaste type.Trial registration: This is not a human subject research.

Analysis of efficacy of the self-assembling peptide-based remineralization agent on artificial enamel lesions.

The objective of this in vitro study was to analyze and compare the biomimetic remineralizing efficacy of the self-assembling peptide (P11-4) with agents containing casein phoshopeptide-amorhous calcium phosphate fluoride (CPP-ACFP) and sodium fluoride (NaF) on artificial caries lesions using DIAGNOdent and micro-computed tomography (μCT). Artificial enamel lesions were prepared on extracted impacted sound mandibular third molars. The samples were randomly allocated to four groups (n = 8): Group 1, P11-4 (Curodont Repair, Credentis AG, Switzerland); Group 2, CPP-ACFP (MI Varnish, GCCo., Japan); Group3, NaF (Duraphat Varnish, Colgate, Colgate-Palmolive, NY, USA); Group 4, artificial saliva (control). The agents were applied to demineralized surfaces according to manufacturers' instructions; all specimens were stored in artificial saliva for 1 month. Demineralization and remineralization on enamel surfaces were analyzed and quantified by DIAGNOdent (KaVo, Germany) and μCT (SkyScan1174, Belgium) for lesion depth/area/volume/mineral density (MD). The remineralization efficacy of the agents was evaluated by DIAGNOdent on 1st, 7th, 30th days and by μCT on 30th day. Data were statistically analyzed by ANOVA, Kruskal-Wallis, T test, and Wilxocon tests. The highest remineralization efficacy findings in all periods were determined in Group 1, followed by Groups 2, 3, and 4. The remineralization findings for fluorescence, MD, lesion depth in Group 1 were found significantly higher (p < 0.01) than Group 3; and no significant differences (p > 0.05) were found between Groups 1-2 and Groups 2-3. The area and volume change values in Groups 1, 2, and 3 have shown no significancy (p > 0.05). A significant correlation (p < 0.01) was found between μCT and DIAGNOdent methods. The data of this study have demonstrated that P11-4 has showed the best remineralization efficacy, followed by CPP-ACFP and NaF. It is concluded that self-assembling peptide-based remineralization agent can be used successfully for biomimetic remineralization of enamel subsurface lesions.

Importance of bioavailable calcium in fluoride dentifrices for enamel remineralization

ObjectivesTo compare remineralization of enamel subsurface lesions by fluoride dentifrices with added calcium in a double-blind, randomized, cross-over, in situ study. MethodsHuman enamel with subsurface lesions were prepared and inserted into intra-oral appliances worn by volunteers. A slurry (1 g toothpaste/4 ml H2O) was rinsed for 60 s, 4 times per day for 14 days. Seven toothpastes were tested: (i) 1450 ppm F (NaF), (ii) 5000 ppm F (NaF), (iii) 1450 ppm F (MFP) with calcium sodium phosphosilicate (CSP), (iv) 1450 ppm F (MFP) with CaCO3/Arg, (v) 1150 ppm F (SnF2) with amorphous calcium phosphate (ACP), (vi) 1100 ppm F (NaF) with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and (vii) 5000 ppm F (NaF) with functionalized tri-calcium phosphate (TCP). Total (acid soluble) and bioavailable (water soluble) calcium, inorganic phosphate and fluoride levels of the dentifrices were measured using ion chromatography (F/MFP) and spectrophotometry (Ca and inorganic phosphate). Enamel lesion mineral content was measured using transverse microradiography. Data were statistically analysed using a linear mixed model. ResultsAll calcium and fluoride containing toothpastes released > 90% of bioavailable fluoride and were superior to the respective fluoride alone toothpastes in remineralization of enamel subsurface lesions. The level of remineralization followed the order: CPP-ACP/1l00 ppm F > ACP/1150 ppm F = TCP/5000 ppm F > 5000 ppm F = CaCO3/Arg/1450 ppm F = CSP/1450 ppm F > 1450 ppm F. Bioavailable calcium levels significantly correlated with enhanced remineralization of enamel subsurface lesions. ConclusionsBioavailable calcium in fluoride dentifrices enhanced remineralization of enamel subsurface lesions.

The Utility of Chewing Gum in Treating White Spot Lesions

White spot lesions (WSL) are early non-cavitated carious lesions where the subsurface mineral loss has produced changes in the optical properties of the enamel. These lesions are visibly detectable as the loss of translucency results in a white appearance of the enamel surface. WSL can be arrested or reversed if the cariogenic challenge is sufficiently controlled or therapeutic agents are applied to promote enamel remineralization. Sugar-free chewing gum has been shown to promote the remineralization of enamel subsurface lesions in situ. Recently, manufacturers have been adding bioavailable calcium and fluoride in various forms to enhance anticariogenic and remineralization potential. This review describes the use of chewing gum which includes bioavailable agents for remineralization of WSL. Chewing gum is a noninvasive clinical approach for WSL remineralization, but further clinical studies are needed. Providing evidence on the effectiveness of these new noninvasive treatment approaches using technologies such as optical coherence tomography remains a priority in dental research.

Effect of arginine dentifrice on remineralization of initial enamel carious lesions

To evaluate remineralization efficacy of an arginine containing dentifrice on initial enamel carious lesions in vitro. Human enamel blocks with early lesions were prepared and randomly divided into three treatment groups: negative control group (distilled and deionized water), positive control group (fluoride containing dentifrice and 0.14% sodium monofluorophosphate), and test dentifrice group (8.0% arginine and 0.14% sodium monofluorophosphate). The lesions were subjected to a pH-cycling regime for 10 days. Surface enamel microhardness of the enamel blocks from each group was measured before and after pH cycling, and the surface microhardness recovery was calculated. Then, specimens were analyzed for enamel fluoride uptake (EFU) through acid etching method, after which they were treated in demineralization solution for a 2 h period of acid challenge. The other specimens were sectioned and examined through polarized light microscopy. In the test dentifrice group, microhardness recovery and EFU were significantly higher than those in the negative control and positive groups. The test dentifrice group was significantly resistant to the acid challenge compared with the other groups. Conspicuous remineralization of enamel subsurface lesions was observed under polarized light microscopy among samples treated with test dentifrice, whereas the control groups showed no significant changes on enamel subsurface lesions. This study presents the potential superiority of Pro-Argin dentifrice over conventional fluoride dentifrice in promoting the remineralization of initial enamel lesions.

Quantitative Light-Induced Fluorescence to Measure Enamel Remineralization in vitro

The aim of this study was to compare the ability of quantitative light-induced fluorescence (QLF) and surface microhardness (SMH) to measure the remineralization of enamel subsurface lesions, using a pH-cycling model including treatment with 0-ppm, 550-ppm or 1,100-ppm sodium fluoride (NaF) dentifrices. Methods: Subsurface lesions were created in human enamel specimens (n = 36) and exposed to a remineralization pH-cycling model for 14 days. The pH-cycling model was performed in an automated system where specimens were subjected to a demineralizing solution for 20 min and treatment for 1 min and were then remineralized for 7 h 39 min, 3 times daily. The treatments consisted of 3 NaF, silica-containing dentifrices (0 ppm F; 550 ppm F; 1,100 ppm F). The outcome variables were: change from baseline in surface hardness and percentage change from baseline in fluorescence. An ANCOVA explored differences between different treatment groups (at the p < 0.05 level). Associations between QLF and SMH were evaluated using Spearman's correlation coefficient. Results: The percentage SMH changes were 14.9 ± 2.1%, 56.6 ± 9.6% and 103.9 ± 14.6% for the 0-, 550- and 1,100-ppm F dentifrices, respectively. The percentage fluorescence changes were 15.6 ± 7.1%, 59.8 ± 11.9% and 85 ± 13.2%, respectively. The differences between all pairwise comparisons were statistically significant for both methods (p = 0.001). QLF correlated with SMH (r = 0.67). Conclusions: Both the SMH and QLF methods demonstrated a significant F dose response for toothpaste in this in vitro remineralization model, and both methods were able to distinguish treatments with different F levels.

Enamel remineralization assessment after treatment with three different remineralizing agents using surface microhardness: An in vitro study

Aim:The aim of this study is to evaluate the enamel remineralization after treatment with three different remineralizing agents using surface microhardness assessment.Materials and Methods:This in vitro study involves 50 enamel samples divided into five groups of 10 samples each. The positive control group consisted of intact enamel and a negative control group consisted of demineralized enamel samples. All groups excluding the positive control group were subjected to demineralization following which three of these groups were remineralized using remineralizing agents (casein phosphopeptide amorphous calcium phosphate [CPP-ACP] [GC tooth mousse], casein phosphopeptide amorphous calcium phosphate with fluoride [CPP-ACPF] [GC tooth mousse plus], sodium fluoride [phos-flur]). The groups treated with remineralizing agents were subjected to pH cycling over a period of 28 days. This was followed with assessment of surface microhardness (Micro Vickers Hardness tester, Matsuzawa Co., Ltd, Toshima, Japan).Statistical Analysis:One-way analysis of variance test and posthoc Tukey test were conducted for multiple group comparison.Results:There was an improved enamel remineralization in the group, remineralized using CPP-ACPF in comparison with the other groups.Conclusion:Casein phosphopeptide with fluoride is a promising material for remineralization of enamel subsurface lesions.

Monitoring remineralization of enamel subsurface lesions by optical coherence tomography

Optical coherence tomography (OCT) is a potential clinical tool for enamel lesion monitoring. Swept-source OCT findings were compared with cross-sectional nanohardness findings of enamel. Subsurface bovine enamel lesions in three groups were subjected to (1) deionized water (control), (2) phosphoryl oligosaccharide of calcium (POs-Ca) or (3) POs-Ca with 1 ppm fluoride for 14 days. B-scans images were obtained at 1310-nm center wavelength on sound, demineralized and remineralized areas after 4, 7, and 14 days. The specimens were processed for cross-sectional nanoindentation. Reflectivity from enamel that had increased with demineralization decreased with remineralization. An OCT attenuation coefficient parameter (μt), derived based on the Beer-Lambert law as a function of backscatter signal slope, showed a strong linear regression with integrated nanohardness of all regions (p<0.001, r=-0.97). Sound enamel showed the smallest, while demineralized enamel showed the highest μt. In group three, μt was significantly lower at four days than baseline, but remained constant afterwards. In group two, the changes were rather gradual. There was no significant difference between groups two and three at 14 days in nanohardness or μt POs-Ca with fluoride-enhanced nanohardness of the superficial zone. OCT signal attenuation demonstrated a capability for monitoring changes of enamel lesions during remineralization.

In vitro remineralization of enamel subsurface lesions and assessment of dentine tubule occlusion from NaF dentifrices with and without calcium

Currently, fluoride is the most effective preventive treatment for remineralization of incipient carious lesions and dentinal hypersensitivity due to wasting disorders. The products containing fluoride, calcium and phosphate are also claim to remineralize early, non-cavitated enamel demineralization. The aim of this study was to investigate and compare the efficacy of two such products, Tooth Mousse and Clinpro tooth crème on remineralization and tubule occluding ability with 5000ppm fluoride-containing toothpaste. Thirty third molar teeth were placed in demineralizing solution for 5 days such that only a window of 1mm x 5mm was exposed to the environment to produce artificial caries-like lesions and randomly assigned to three groups: Group I, 5000ppm sodium fluoride; Group II, GC MI paste plus and Group III, Clinpro tooth crème. Axial longitudinal sections of 140-160 μm of each tooth which included the artificial carious lesion taken and were photographed under polarized light microscope. The demineralized areas were then quantified with a computerized imaging system. The experimental materials were applied onto the tooth sections as a topical coating and subjected to pH-cycling for 28 days. To evaluate tubule occlusion ability, thirty dentin specimens of 2mm thickness were obtained from cervical third of sound third molars. Specimens were ultrasonicated and etched with 6% citric acid for 2 minutes to simulate the hypersensitive dentin. Specimens were randomly divided into above mentioned three groups (n=10). The test agents were brushed over the specimens with an electric toothbrush, prepared and observed under Scanning Electron Microscope for calculation of the percentage of occluded tubules. Group I showed a significantly greater percentage of remineralization than Group III and Group II. Comparison of the remineralization potential between group II and group III were not significant.In case of dentine hypersensitivity, Group I and group III showed greater percentage of tubule occlusion ability than Group II. Intergroup comparison of the tubule occlusion potential of group I and group III were not significant. Within the limitations of our study, sodium fluoride showed relatively greatest remineralizing and dentinal tubule occlusion property when compared with GC MI paste plus and Clinpro tooth crème.

Comparison of quantitative light‐induced fluorescence, digital photography and transverse microradiography for quantification of enamel remineralization

Quantitative light-induced fluorescence (QLF) and digital photography (DP) have been proposed as clinical methods for measuring changes in enamel mineral content. The aim of this study was to compare the ability of QLF and DP with the in vitro gold standard transverse microradiography (TMR) to measure the remineralization of enamel subsurface lesions. Subsurface lesions were formed in enamel (n = 40) and exposed to remineralization solutions for 10 days. Changes were analysed by DP, QLF and TMR to determine percentage changes in luminescence (%L), fluorescence (%F) and mineral content (%R), respectively and correlation between these parameters determined. The correlations between TMR and QLF (r = 0.63), TMR and DP (r = 0.59), and DP and QLF (r = 0.64) were all moderate but statistically significant (p < 0.001). The variability in %L and, to a lesser extent, %F values significantly impacted on the potential role of DP and QLF as methods by which mineral content changes produced by remineralization treatments could be accurately measured. Both QLF and DP provided data that correlated moderately with TMR data. QLF images were easier to analyse, free of glare and had less variability compared with those produced using DP.

Remineralization of enamel subsurface lesions with casein phosphopeptide-amorphous calcium phosphate: A quantitative energy dispersive X-ray analysis using scanning electron microscopy: An in vitro study

Aim:The objective of this study was to quantitatively evaluate the remineralization potential of casein phosphopeptide-amor-phous calcium phosphate paste on enamel subsurface lesions using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX).Materials and Methods:Ninety enamel specimens were prepared from extracted human molars. All specimens were evaluated for mineral content (% weight) using SEM-EDX. The specimens were placed in demineralizing solution for four days to produce artificial carious lesions. The mineral content (calcium/phosphorus ratios, Ca/P ratios) was remeasured using SEM-EDX. The specimens were then randomly assigned to five study groups and one control group of 15 specimens per group. Except for the control group, all group specimens were incubated in remineralizing paste (CPP-ACP paste) for 7, 14, 21, 28, and 35 days twice daily for three minutes. The control group received no treatment with remineralizing paste. All the 90 specimens were stored in artificial saliva at 37°C. After remineralization, the mineral content (% weight) of the samples was measured using SEM-EDX.Results:All the study groups showed very highly significant differences between Ca/P ratios of the demineralized and remineralized samples. There was no significant difference seen in the control group.Conclusion:CPP-ACP paste could significantly remineralize the artificial enamel subsurface lesions in vitro: the remineralizing rates increasing with the time for which the samples were kept in the remineralizing paste. Energy dispersive X-ray analysis is an efficient way to quantitatively assess the changes in mineral content during demineralization and in vitro remineralization processes.

Effect of added calcium phosphate on enamel remineralization by fluoride in a randomized controlled in situ trial

Dental products containing calcium phosphate and fluoride are claimed to enhance enamel remineralization over fluoride products. ObjectivesTo compare remineralization of enamel subsurface lesions by dental products with added calcium phosphate in a double-blind, randomized, cross-over in situ study. MethodsHuman enamel specimens with subsurface lesions were prepared and inserted into intra-oral appliances worn by volunteers. A slurry (1g product plus 4ml H2O) of each product was rinsed for 60s, 4 times per day for 10 days. Six products were tested (i) placebo, (ii) 1000ppm F, (iii) 5000ppm F, (iv) Tooth Mousse (TM), (v) TM plus 900ppm F (TMP) and (vi) Clinpro with 950ppm F. Calcium, inorganic phosphate and fluoride levels were measured in post-rinse/saliva samples using ion chromatography. Mineral content was measured using transverse microradiography. ResultsOnly TM and TMP significantly increased salivary calcium and phosphate levels. The products produced remineralization in the following order from lowest to highest: placebo<1000ppm F=Clinpro<5000ppm F<TM<TMP. ConclusionClinpro was not significantly different to 1000ppm F whereas TM and TMP were superior to 5000ppm F with TMP producing the highest level of enamel lesion remineralization.

Remineralization of enamel subsurface lesions by chewing gum with added calcium

Objectives Chewing sugar-free gum has been shown to promote enamel remineralization. Manufacturers are now adding calcium to the gum in an approach to further promote enamel remineralization. The aim of this study was to compare the remineralization efficacy of four sugar-free chewing gums, two containing added calcium, utilizing a double-blind, randomized, crossover in situ model. Methods The sugar-free gums were: Trident Xtra Care, Orbit Professional, Orbit and Extra. Ten subjects wore removable palatal appliances with four human-enamel half-slab insets containing subsurface demineralized lesions. For four times a day for 14 consecutive days subjects chewed one of the chewing gums for 20 min. After each treatment the enamel slabs were removed, paired with their respective demineralized control slabs, embedded, sectioned and mineral level determined by microradiography. After 1-week rest the subjects chewed another of the four gums and this was repeated until each subject had used the four gum products. Results Chewing with Trident Xtra Care resulted in significantly higher remineralization (20.67 ± 1.05%) than chewing with Orbit Professional (12.43 ± 0.64%), Orbit (9.27 ± 0.59%) or Extra (9.32 ± 0.35%). The form of added calcium in Trident Xtra Care was CPP–ACP and that in Orbit Professional calcium carbonate with added citric acid/citrate for increased calcium solubility. Conclusions Although saliva analysis confirmed release of the citrate and calcium from the Orbit Professional gum the released calcium did not result in increased enamel remineralization over the normal sugar-free gums. These results highlight the importance of calcium ion bioavailability in the remineralization of enamel subsurface lesions in situ.

Remineralization of enamel subsurface lesions in situ by the use of three commercially available sugar‐free gums

Commercially available sugar-free chewing gums have been claimed to provide oral health benefits. The aim of this randomized, double-blind crossover in situ study was to compare the efficacy of three commercially available sugar-free chewing gums: Trident White, Orbit, and Orbit Professional, in remineralizing enamel subsurface lesions in situ. Specimens containing enamel subsurface lesions were sectioned into test and control half-slabs with the test half-slabs inserted into removable palatal appliances. For each test chewing period, subjects were randomly allocated one of three test gums. Subjects (n = 10) chewed the randomly allocated gum for a 20-min period four times per day for 14 days. Each subject chewed all three test gums, with a 7-day washout period between crossovers. After each 14-day cycle, test and control half-slabs were paired, embedded in resin, sectioned, and subjected to microradiography to determine remineralization. The gum TW produced significantly greater remineralization (18.4 +/- 0.9%) than Orbit (8.9 +/- 0.5%) and Orbit Professional (10.5 +/- 0.9%). The superior remineralization activity of the TW gum in situ was attributed to the presence of casein phosphopeptide-amorphous calcium phosphate nanocomplexes.

The Effect of Nano-Sized β-Tricalcium Phosphate on Remineralization in Glass Ionomer Dental Luting Cement

This study aimed to evaluate the anticariogenic and remineralization effects of the glass ionomer dental luting cement containing nano-β-TCP in vitro. The β-Tricalcium Phosphate (β-TCP) are the components of dental enamel and bone mineral as biological apatites. In addition, β-TCP contains a significant amount of calcium and phosphate, which can promote remineralization of enamel subsurface lesions in animal and human. RelyXTM glass ionomer cement(3M/ESPE, USA) was used as dental luting cement. Film thickness, setting time, and compressive strength was measured for each group of pure glass GIC, 15% nano-β-TCP GIC. Human molars were prepared in box-shaped cavities that were filled with the GIC with and without the 15% nano-β-TCP were placed in 25ml of pH 5.0 acid buffer for 4 days at 37°C. After 4 days, longitudinal sections (1007m) were obtained through the center of each restoration. The sections were analyzed using a scanning electronic microscope (SEM) and confocal laser scanning microscopy (CLSM) to identify the change in the enamel surface. A significant difference in the CLSM images between pure GIC and nano-β-TCP-GIC. CLSM allows the demineralized surface layers of sound enamel to be visualized down to approximately 100 μm. The pure GIC specimens had a relatively thick fluorescent layer. On the other hand, the fluorescent layer of the nano-β-TCP-GIC specimens were thinner. The SEM images of micro surfaces demonstrate that nano-β-TCP-GIC is less rough than pure GIC. Therefore, the addition of nano-β-TCP enhanced protection against acid demineralization and promoted remineralization of enamel surface.

Acid Resistance of Enamel Subsurface Lesions Remineralized by a Sugar-Free Chewing Gum Containing Casein Phosphopeptide-Amorphous Calcium Phosphate

The aim of this clinical study was to investigate the acid resistance of enamel lesions remineralized in situ by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP: Recaldent™). The study utilized a double-blind, randomized, crossover design with two treatments: (i) sugar-free gum containing 18.8 mg of CPP-ACP, and (ii) sugar-free gum not containing CPP-ACP as control. Subjects wore removable palatal appliances with insets of human enamel containing demineralized subsurface lesions and chewed the gum for 20 min 4 times per day for 14 days. After each treatment the enamel slabs were removed and half of each lesion challenged with acid in vitro for 8 or 16 h. The level of remineralization was determined using microradiography. The gum containing CPP-ACP produced approximately twice the level of remineralization as the control sugar-free gum. The 8- and 16-hour acid challenge of the lesions remineralized with the control gum resulted in 65.4 and 88.0% reductions, respectively, of deposited mineral, while for the CPP-ACP-remineralized lesions the corresponding reductions were 30.5 and 41.8%. The acid challenge after in situ remineralization for both control and CPP-ACP-treated lesions resulted in demineralization underneath the remineralized zone, indicating that the remineralized mineral was more resistant to subsequent acid challenge. The results show that sugar-free gum containing CPP-ACP is superior to an equivalent gum not containing CPP-ACP in remineralization of enamel subsurface lesions in situ with mineral that is more resistant to subsequent acid challenge.

Incorporation of casein phosphopeptide-amorphous calcium phosphate into a glass-ionomer cement.

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) nanocomplexes have been shown to prevent demineralization and promote remineralization of enamel subsurface lesions in animal and in situ caries models. The aim of this study was to determine the effect of incorporating CPP-ACP into a self-cured glass-ionomer cement (GIC). Incorporation of 1.56% w/w CPP-ACP into the GIC significantly increased microtensile bond strength (33%) and compressive strength (23%) and significantly enhanced the release of calcium, phosphate, and fluoride ions at neutral and acidic pH. MALDI mass spectrometry also showed casein phosphopeptides from the CPP-ACP nanocomplexes to be released. The release of CPP-ACP and fluoride from the CPP-ACP-containing GIC was associated with enhanced protection of the adjacent dentin during acid challenge in vitro.

Remineralization of enamel subsurface lesions by casein phosphopeptide-stabilized calcium phosphate solutions.

Casein phosphopeptides (CPP) stabilize amorphous calcium phosphate (ACP), localize ACP in dental plaque, and are anticariogenic in animal and in situ human caries model. In this vitro study, CPP-stabilized calcium phosphate solutions were shown to remineralize subsurface lesions in human third-molar enamel. Solutions were used to examine the effect of CPP-calcium phosphate concentration on remineralization. Other solutions were used to examine the effect of increasing pH, which decreased the concentrations of free calcium and phosphate ions and increased the level of CPP-bound ACP. Although most of the remineralizing solutions were supersaturated with respect to the amorphous and crystalline calcium phosphate phases, the solutions were stabilized by the CPP such that spontaneous precipitation of calcium phosphate did not occur. After a ten-day remineralization period, enamel lesions were sectioned, subjected to microradiography, and the mineral content determined by microdensitometry. All solutions deposited mineral into the bodies of the lesions, with the 1.0% CPP-calcium phosphate (pH 7.0) solution replacing 63.9 +/- 20.1% of mineral lost at an averaged rate of 3.9 +/- 0.8 x 10(-8) mol hydroxyapatite/m2/s. The remineralizing capacity was greater for the solutions with the higher levels of CPP-stabilized free calcium and phosphate ions. Remineralization was not significantly correlated with either the CPP-bound ACP of the degrees of saturation for hydroxyapatite, octacalcium phosphate, or ACP. However, remineralization was significantly correlated with the degree of saturation for dicalcium phosphate dihydrate (CaHPO4.2H2O), but his was attributed to the significant correlation of remineralization with the activity gradients from the solution into the lesion of some calcium phosphate ions and ion pairs, in particular the neutral ion pair CaHPO4(0). The CPP, by stabilizing calcium phosphate in solution, maintain high-concentration gradients of calcium and phosphate ions and ion pairs into the subsurface lesion and thus effect high rates of enamel remineralization.