Degree Of Remineralization Research Articles

THE USE OF RAMAN FLUORESCENCE TECHNOLOGY TO EVALUATE THE EFFECTIVENESS OF REMINERALIZATION OF SOLID TOOTH TISSUE

The purpose of the study-to justify the effectiveness of the method of Raman-fluorescence diagnostics in the assessment of the remineralisation of the hard tissues of the tooth. In preclinical in vitro study on the model 25 the test object teeth (the incisors of the lower jaw) removed as clinically indicated, carried out Raman-fluorescence spectroscopy with a wavelength of probe radiation of 532 nm. The advantages of Raman-fluorescence spectroscopy are expressiveness, noninvasiveness, simple and non-destructive control of the degree of remineralization of hard tooth tissues [1-3]. In the course of the study, a qualitative and quantitative analysis of the content and distribution of hydroxyapatite in the enamel in the normal and with the use of remineralizing drugs was carried out. The high sensitivity and reproducibility of the method allowed us to assess the degree of mineralization of the tooth, the effectiveness of remineralizing drugs.

Role of enamel deminerlization and remineralization on microtensile bond strength of resin composite.

Objective:This study is aimed to establish the microtensile bond strength of enamel following exposure to an aerated drink at various time intervals with/without application of remineralization agent. In addition, degree of remineralization and demineralization of tooth enamel has been assessed using polarized light microscopy.Materials and Methods:Seventy extracted human incisors split into two halves were immersed in aerated beverage (cola drink) for 5 min and stored in saliva until the time of microtensile bond testing. Prepared specimens were divided randomly into two study groups; remineralizing group (n = 70): specimens were treated for remineralization using casein phosphopeptides and amorphous calcium phosphate (CPP-ACP) remineralization agent (Recaldent™; GC Europe) and control group (n = 70): no remineralization treatment; specimens were kept in artificial saliva. All specimens were tested for microtensile bond strength at regular intervals (1 h, 1 days, 2 days, 1 week, and 2 weeks) using a universal testing machine. The results statistically analyzed (P = 0.05) using two-way ANOVA test.Results:Results showed statistically significant increase in bond strength in CPP-ACP tested group (P < 0.05) at all-time intervals. The bond strength of remineralizing group samples at 2 days (~13.64 megapascals [MPa]) is comparable to that of control group after 1 week (~12.44 MPa).Conclusions:CPP-ACP treatment of teeth exposed to an aerated drink provided significant increase in bond strength at a shorter interval compared to teeth exposed to saliva alone.

Activity assessment of root caries lesions with thermal and near-IR imaging methods.

The purpose of this study was to evaluate thermal and near-infrared (NIR) reflectance imaging methods for the assessment of the activity of root caries lesions. In addition, changes in the lesion structure were monitored with polarization sensitive optical coherence tomography (PS-OCT). Artificial bovine and natural root caries lesions were imaged with PS-OCT, and their dehydration rate was measured with thermal and NIR cameras. The lesion activity of the natural root caries samples was also assessed by two clinicians by conventional means according to ICDAS II guidelines. The thickness of the highly mineralized transparent surface layer measured using PS-OCT increased and the area enclosed by the time-temperature curve, ΔQ, measured with thermal imaging decreased significantly with longer periods of remineralization in simulated dentin lesions, but the NIR reflectance intensity differences, ΔI, failed to show any significant relationship with the degree of remineralization. The PS-OCT algorithm for the automated assessment of remineralization successfully detected the highly mineralized surface layer on both natural and simulated lesions. Thermal imaging provided the most accurate diagnosis of root caries lesion activity. These results demonstrate that thermal imaging and PS-OCT may be ideally suited for the nondestructive root caries lesion activity during a clinical examination.

Assessment of remineralization via measurement of dehydration rates with thermal and near-IR reflectance imaging

ObjectivesPrevious studies have demonstrated that the optical changes due to the loss of water from porous lesions can be exploited to assess lesion severity with QLF, thermal and near-IR imaging. Since arrested lesions are less permeable to water due to the highly mineralized surface layer, changes in the rate of water loss can be related to changes in lesion structure. The purpose of this study was to investigate whether the rate of water loss correlates with the degree of remineralization and whether that rate can be measured using thermal and near-IR reflectance imaging. MethodsArtificial bovine enamel lesions (n=30) were prepared by immersion in a demineralization solution for either 8 and 24h and they were subsequently placed in an acidic remineralization solution for different periods. The samples were dehydrated using an air spray for 30s and surfaces were imaged using a thermal camera and an InGaAs camera at 1300–1700nm wavelengths. ResultsThe area enclosed by the time–temperature curve, ΔQ, from thermal imaging showed significant differences (P<0.05) between the lesion window and other windows. Near-IR reflectance intensity differences, ΔI, before and after dehydration decreased with longer periods of remineralization. Only near-IR reflectance imaging was capable of detecting significant differences (P<0.05) between the different periods of remineralization. ConclusionsThis study demonstrated that both thermal and near-IR reflectance imaging were suitable for the detection of remineralization in simulated caries lesions and near-IR wavelengths longer than 1400nm are well suited for the assessment of remineralization.

Design Considerations of a Packed Calcite Bed for Hardening Desalinated Water

Desalinated water is poor in minerals, making it corrosive and unpalatable. A certain degree of remineralization is necessary in order to overcome these problems as well as to meet health requirements. A commonly used remineralization process is to pass desalinated water dosed with either CO2 or H2SO4 through a bed of limestone, reintroducing bicarbonate alkalinity and calcium hardness to the water. The paper presents cumulative experimental evidence confirming the reliability of the kinetic model developed by Yamauchi et al. and Letterman et al. The paper also analyzes the main operational parameters affecting the minimum cost design of a hardening column. Finally, the viability of incorporating a CO2 desorption process so as to reduce alkali consumption is examined.

The Effects of Calcified Seaweed on Remineralization of Artificially Demineralized Dentin

The study investigated the remineralization effect of calcified seaweed with large amounts of calcium (Ca), magnesium (Mg), sodium (Na), fluorine (F) and phosphorus (P). Human third molars were used in the experiment with the approval of the Ethics Committee of Tokyo Dental College. Cementum was removed from the cervical area around the teeth exposing the dentin. Small dentin blocks were prepared and immersed in acetic acid-sodium acetate buffer for 24 hours. Samples were immersed in remineralized liquid or saliva solution with or without calcified seaweed for 2 weeks. Structural changes in remineralization, depth of demineralization and loss in mineral volume were evaluated by contact microradiogram (CMR). Qualitative analysis was carried out with electron probe microanalyzer (EPMA). Morphology of crystal was observed using high-resolution transmission electron microscopy (HR-TEM). CMR image analysis revealed that part of the samples immersed in the solutions underwent remineralization. However, there was no significant difference in the degree of remineralization. EPMA observation of dentin partly detected Ca and P but not Mg or F. HR-TEM analysis revealed changes in crystal structure caused by Mg and F, which influenced remineralization in a small amount.

Qualitative analysis of re mineralized carious lesions subjected to fluoride supplement through confocal laser scanning microscope

Aim: 1] Comparative evaluation of the linear depth of induced remineralized lesions after subjecting to fluoride supplements and 2] To assess the average fluorescence at both the demineralized and the remi-neralized zones in all the three study groups under confocal laser scanning microscope. Method: Forty five sound human premolars extracted for orthodon-tic reasons were decoronated 1 mm below the ce-mento-enamel junction and coated with nail varnish except for a 3 × 3 mm window on the buccal surface. The samples were placed in 50 ml of de mineralizing solution at pH 4.6 for 96 hours. Following deminera-lization, the lower half of the 3 × 3 mm window in all the samples were covered with nail varnish to serve as control. The samples were randomly divided into three groups of fifteen teeth each (n = 15) and speci-mens in group A[Nfd] were remineralized using non-fluoridated dentifrice [control], those in groups B [Fd5] and group C [Fd10] using 500 ppm and 1000 ppm of fluoride containing dentifrice, respectively. The specimens were subjected to a 20 day reminera-lization treatment regimen and were sectioned into 100 µm thick sections and two images were captured on the buccal surface from either side of the midpoint of occluso-cervical length using confocal laser scan-ning microscope [CLSM]. Results: were tabulated and statistically analyzed by Anova. Study concluded that 1000 ppm fluoridated dentifrice showed a greater degree of remineralization than other groups and confocal laser scanning microscopes gives promising results in the diagnosis of early enamel lesions over the conventional methods.

Wear behavior of early carious enamel before and after remineralization

The purpose of the research was to evaluate the effect of remineralization treatment on the wear behavior of human early carious enamel. The degree of remineralization was observed with polarized light microscope and microhardness tester. Then the tribological properties of all the specimens were investigated by a CSEM nano-stratch tester system. The results showed that the hardness and density of carious enamel increased obviously, and the friction coefficient became higher after remineralization. It was easier to form cracks and debris on the remineralized enamel. It was concluded that the most effective remineralization agent (fluoride) in clinic could decrease the wear resistance of early carious enamel. There was no direct relationship between the content of minerals and the wear resistance of early carious enamel. The wear resistance of enamel could not be improved veritably by increasing the hardness. The main damage mechanisms of early carious enamel were the plastic deformation and adhesive wear while those of remineralized one were the combination of brittle cracks, plastic deformation and brittle delamination. New technique of remineralization is urgently needed clinically to improve the wear resistance.

Early detection of white spot lesions with digital camera and remineralization therapy

In this paper, the characteristics of the early stage of dental caries are discussed and the methods we used to treat the early stage of dental caries to increase the number of caries-free patients are presented. Studies from in vitro to in situ experiments and a clinical study were carried out to support clinical remineralization therapy. To clarify the effect of time for remineralization, the degree of remineralization was assessed at 2 days, 6 days, and 10 days after 2-day demineralization in 0.01 M/L lactic acid buffer (pH 4.0 at 37 degrees ). The remineralization solution contained 3.0 mM/L Ca, 1.8 mM/L P, and 3 ppm fluoride adjusted to pH 7.0. A 10-day continuous remineralization with a 3 ppm fluoride resulted in a high fluoride concentration. To evaluate mineral loss from sound tooth structure and white spot lesions, thin sections (about 90 microm) including white spots (WS) were prepared and exposed to oral conditions for 2 weeks continuously. The mineral loss from sound tooth structure was found to be twice that from WS. In another experiment during the remineralization period, enamel samples were immersed in three different bicarbonate solutions; 0.5, 5.0 and 50 mM/L for 30 minutes, two times per day. Both the bicarbonate and fluoride applied groups showed higher improvement in acid resistance and the amount of remaining mineral was almost two times higher than the controls (p < 0.01). In a clinical study we demonstrated remineralization in patients who followed professional mechanical tooth cleaning and fluoride prophylaxis paste. Using this regime, in patients with deciduous caries present at baseline, over 80 per cent of permanent teeth were caries free at the age of 12 years. In these studies the digital camera with CasMaTCH and an image analysis system showed several advantages for monitoring in de- and remineralization. White spot lesions, rather than intact tooth surfaces, can be mineralized through the daily clinical procedures described in this paper.

Remineralization of human dentin using ultrafine bioactive glass particles

Bioactive glass nanoparticles synthesized by flame spray synthesis were tested for their remineralization capabilities in vitro. After artificial demineralization with EDTA, human dentin was treated with 20–50 nm size bioactive glass nanoparticles or a micrometer-sized, commercial reference material (PerioGlas) for up to 30 days. The degree of remineralization was measured using quantitative gravimetric methods (thermogravimetry, elemental analysis) and element-sensitive scanning electron microscopy imaging to detect new mineral precipitated on or within the demineralized tooth matrix. After treatment with bioactive glass nanoparticles for 10 or 30 days a pronounced increase in mineral content of the dentin samples suggested a rapid remineralization. The mechanical properties of the remineralized dentin samples were well below the stability of natural dentin. It is suggested that this lack of mechanical reconstitution may be attributed to an imperfect arrangement of the newly deposited mineral within the demineralized tooth matrix. Nevertheless, the substantially higher remineralization rate induced by nanometer-sized vs. micrometric bioactive glass particles corroborated the importance of particle size in clinical bioglass applications.

Combined Effects of Nano-Hydroxyapatite and NaF on Remineralization of Early Caries Lesion

A previous study reported that many supplements have been added to NaF mouthrinses to improve the remineralization potential. Nano-hydroxyapatite (nano-HA) might also be suitable to this purpose because these nano-size particles can penetrate the enamel pores. Moreover, hydroxyapatite is similar to the inorganic component of teeth and is both bioactive and biocompatible. The aim of this study was to evaluate the combined effects of a nano-HA and fluoride mouthrinse on an early caries lesion in human enamel using an in vitro cycle remineralization and treatment model. Forty-eight human enamel specimens, which had a Vickers Hardness Number (VHN) of 25~45 were artificially demineralized for 48h. There were 8 treatment groups (0%, 1%, 5%, 10% nano-HA in distilled water and the same concentrations of nano-HA in a 0.05% NaF solution). The specimens were incubated in an in vitro remineralization model. After immersing the specimens into the treatment and remineralization solution for 12 hours each, the VHN of each specimen was evaluated for total 24 hours. This step was repeated once again for total 48 hours. The enamel surfaces of all specimens were examined by Confocal Laser Scanning Microscopy (CLSM) and SEM. The statistical significance of the data was identified by one-way ANOVA followed by a Duncan’s studentized range test. A p value &lt; 0.05 was considered significant. The results showed that the degree of remineralization, as revealed by the VHN values, was higher in the NaF groups than in the distilled water groups. The VHNs of the remineralized enamel specimens for 48 hours were higher than after the 24 hours treatment. In addition, the level of remineralization increased with increasing concentration of nano-HA and was more pronounced in the NaF groups than the distilled water groups (p&lt;0.05). The CLSM and SEM images nano-sized particles attached to the enamel in the nano-HA treated groups. Nano-HA might play a synergistic role in remineralization with a fluoride mouthrinse. However, more study will be needed to determine the optimal condition of nano-HA and NaF mouthrinse for human use. In conclusion, nano-HA in a 0.05% NaF mouthrinse can help remineralize an early caries lesion.

Carbon and Nitrogen Spatial Segregation and Stoichiometry in the Surface Sediments of Southern Chilean Inlets (41°–56°S)

The surface sediment of the Chilean Inlets Region has been extensively studied during three major cruises: Cimar Fiordo Cruise 1 in the Upper Area (41°20′S to 46°40′S), Cimar Fiordo Cruise 2 in the Middle Area (46°40′to 47°10′S) and Cimar Fiordo Cruise 3 in the Lower Area (52°19′S to 55°58′S). Total and organic carbon were analysed in 174 sediment samples with an LECO CR-12 elemental analyser. Organic nitrogen was determined using the micro-Kjeldhal technique. Methods were calibrated against standard reference materials certified by the National Institute of Standards and Technology, U.S.A.The study areas were geographically segregated into nine zones according to carbon and nitrogen concentration and distribution. Three of the areas, with comparatively high organic carbon (>1·6%) and organic nitrogen (>0·2%) abundance, were associated with geographically protected inlets and productive planktonic zones. A further four areas with comparatively low organic carbon (<0·8%) and nitrogen (<0·2%) were associated with low planktonic production due to glacial influence. Finally, two areas were associated with carbonate-rich sediments (4–10% inorganic carbon).In the Upper Area the zonal definition followed a north–south pattern due to the presence of the Corcovado Gulf, which is under the oceanic influence of the West Wind Drift current. Conversely, the Middle Area followed an east–west pattern arising from the ‘Campo de Hielo Norte’ and ‘Campo de Hielo Sur’ glacial fields. A southward trend of diminishing organic carbon content was also noted throughout the Inlets Region.Based on the computed carbon-nitrogen ratios for the previous zones, (C:N range of 5·4 to 11·4), the origin of the organic matter present in the surface sediment was deduced. The C:N values can be chiefly associated to sediment of marine origin, with some degree of remineralization. The edaphic input did not appear to play an important role. Furthermore, the results suggest that the anthropogenic influence on the region is minimal, and thus could be considered as a pristine environment.

根面再石灰化の初期過程におけるミネラル量の変化 単一切片法と画像定量法による評価

Early remineralization in root surfaces with cementum was evaluated by conbining a single-section technique with videodensitometry.A total of 10 root sections 125-μm thick were cut individually from 10 samples of freshly extracted sound human premolars and coated with nail varnish leaving a window on the cementum surfaces. After demineralization by immersion in 0.01M lactate buffer (6mM Ca, 3.6mMP, 1% CMC, pH 5.1) at 37°C for 48 hours, all specimens were immersed in remineralizing solution (3mM Ca, 1.8mMP, 150mM NaCl, 2ppm F, 1% CMC, pH 7.0) at 37°C for 7 days. The changes in mineral volume were assessed quantitatively by videodensitometry for the microradiographs prepared before and after remineralization.Results were as follows:(1) Approximately half the mineral volume accumulated during the 7-day remineralization was acquired whthin the first 2days. This fact indicates that the degree of remineralization in root surfaces progresses rather rapidly.(2) From the digitized microradiographic images, initial remineralizing sited appeared to be located in the subsurface layer of cementum.(3) We suggest that the degree of in vitro remineralization should be evaluated within a short period when a seingle-section technique is used.

ｉｎ ｖｉｔｒｏにおける根面初期う蝕の再石灰化とフッ素取り込みにおよぼす各種フッ化物の効果に関する研究

The effects of the application of various fluorides on the remineralization and fluoride (F) incorporation of root surfaces with or without cementum were evaluated in vitro. Clinincally sound proximal root surfaces of premolars extracted from patients aged 9-14 years were used for experiments and divided into two categories: (1) a dentin group, where cementum was removed by abrasion, and (2) a cementum group, where the cementum was preserved. In both groups, two types of specimens were prepared: (1) sandwich specimens, for assessing mineral volume by a single section technique, and (2) block specimens, for the determination of F incorporation by biopsy.After demineralization by immersion in 0.01M (for sandwiches, pH 5.1, 6mM Ca, 3.6mM P, 1% CMC, 37°C) or 0.1M (for blocks, pH 5.0, 3mM Ca, 1.8mM P, 1% CMC, 37°C) lactate buffer, specimens were treated with one of the following four fluorides during 14-day immersion in remineralizing solution (Rem solution: 3mM Ca, 1.8mM P, 150mM NaCl, 3ppm F, 1% CMC, pH 7.0, 37°C). The fluorides were APF solution (APF), APF gel (FG), F rinse solution (FR) and MFP dentifrice (FD). Control group (immersion in 3ppm F containing Rem solution only) and negative control group (immersion in F free Rem solution only) were also studied. APF and FG were applied for 4 minutes once just before remineralization, and FR and FD were applied for 1 minute every 24-hour remineralizing period. Sandwinch specimens were microradiographed before and after remineralization. The film density of lesions was convereted to aluminum thickness (Ta; μm) and the mineral volume of lesion (Ma; μm·μm) was defined as integrated values of Ta profiles. F content was determined by acid etch biopsy with 0.5M HClO4.The Results were as follows:Remineralization of early root caries lesion in vitro was(1) promoted by the application of fluorides, and accelerated more by the treatment with APF or FG than the treatment with FR or FD, and(2) not significantly different between the cementum and the dentin groups.(3) Cementum had no inhibitory effects on the remineralization of root surfaces.F incorporation in remineralized root surfaces were(1) different between various F treatments, and specimens treated with APF or FG showed significantly higher F uptake level, and(2) greater in the cementum group than that in the dentin group and this fact indicates that cementum would be important tissue for demineralization and remineralization of root sufaces as a source of F ion supply.According to the analysis of correlation coefficient, the degree of remineralization was obviously dependent on F incorporation in lesion surfaces.In conclusion, these findings suggested that F application was effective for the remineralization of root surfaces and F incorporation into root surfaces did not depend on cementum. Thus, professional or self application of fluorides was considered to be higly suitable for the prevention of root caries in the elderly.

脱灰エナメル質の再石灰化に及ぼすレーザー照射の影響

The purpose of this study was to examine the influence of laser irradiation on remineralization of demineralized enamel. Twenty human premolar enamel slabs (3×5mm) were prepared for this study. The enamel slabs were ground down to about 400μm and immersed in 0.1M lactic acid buffer (3.0mM Ca, 1.8mM P, 1.0% carboxymethylcellulose, pH 4.5, 37°C) for 12 hours. Demineralized enamel slabs were irradiated with a Q-switch Nd-YAG laser at 50 J/cm2of total energy density. After laser irradiation, slabs were immersed in remineralizing solution (3.0mM Ca, 1.8mM P 1.0% carboxymethylcellose, 150mM NaCl, 3.0ppm F, pH 7.0, 37°C) for 10 days. The degree of remineralization was evaluated by microradiograph using calculated mineral content. Sectioned enamel slabs were also immersed in 0.5M HClO4solution for 1 minute to examine acid resistance of the remineralized enamel.There were signs of remineralization in both the lased and unlased areas, and no clearly difference was recognized between these areas. It appears that remineralization of enamel was not inhibited by laser irradiation. The acid resistance of the remineralized enamel was higher in the lased area than in the unlased area. However, the degree of remineralization corresponding to the mineral level was not significantly different between two areas. It is probable that the permeability of enamel was not decreased by laser irradiation.

脱灰エナメル質のフッ素取り込みと再石灰化に及ぼすカルボキシメチルセルロースの効果

The effect of carboxymethylcellulose (CMC) on enamel remineralization was investigated in in vitro. CMC is a component of artificial saliva substitutes and may be considered as a model molecule for the salivary mucins. Human dental enamel slabs (N=60) were demineralized for 12 hours by immersion in a demineralizing solution containing 0.1M lactic acid, 3.0mM Ca, 1.8mM P, and 1% CMC at pH 4.5. After demineralization, the enamel slabs were immersed in four groups of remineralizing solutions for 10days (20ml/slab), which contained 3.0mM Ca, 1.8mM P, and 150mM NaCl at pH7.0, with and without 1% CMC and 3ppm fluoride, that is, (1) 0% CMC/0ppm F (C0F0), (2) 1% CMC/0ppm F (C1F0), (3) 0% CMC/3ppm F (C0F3), and (4) 1 % CMC/3ppm F (C1F3). After remineralization, the degree of remineralization were evaluated by chemical analysis for Ca amount, Ca/P ratio, and fluoride uptake, and by microradiography using calculated mineral vol%. The remineralized enamel slabs were treated with 1.0N HClO4 solution to evaluate the acid resistance and also the mineral vol% was reevaluated by microradiography. The following results were obtained.1) The fluoride uptake in group C1F3 was about two times higher than that of group C0F3 for the first to fourth layers (p<0.05). 2) According to the microradiography evaluation of group C1F0, the lowest mineral vol% was evident. Groups C0F0, C0F3, and C1F3 were obviously remineralized, but the mineral vol% of group C0F3 was lower than that of groups C0F0 and C1F3. 3) A radiopaque zone, indicating acid resistance, was not found in group C1F0, but the other three groups showed acid resistant zones. The microradiographic characteristics of the acid resistant zone in groups C0F3 and C1F3 were uniform. This zone was formed through the remineralized area, particularly at the surface and bottom layer of the remineralized area. In group C0F0, however, such uniformity was not found. 4) The Ca amount and Ca/P ratio were not sufficient to evaluate the degree of remineralization.These results suggest that not only the CMC molecule, which is relatively large (50, 000-12, 000), inhibits remineralization without fluoride ions, but also, that the CMC molecule promotes fluoride uptake and the degree of remineralization with fluoride ions.

Ｉｎ ｖｉｖｏにおける各種フッ化物応用後の脱灰エナメル質へのフッ素取り込みと再石灰化

The fluoride uptake and remineralization of partially demineralized enamel after various fluoride applications for 10 days were investigated in vivo. The fluoride applications involved use of MFP dentifrice twice a day; 100ppmF mouthrinse once a day; acidulated phosphate fluoride (APF) applied only once; or no treatment (control). The degree of remineralization was evaluated by mineral vol% using microradiography. The following results were obtained.1) The fluoride uptake from dentifrice and mouthrinse were about 1.2-1.5 and 2-3 times higher than that of the controls, respectively. But statistically significant differences were not found between these three groups. The fluoride uptake from APF treatment was about 14-15 times higher than that of the controls, and statistically significantly higher than the other three groups from the first to the fifth layer.2) The remineralization was evident in all four groups except in one control case. The degree of remineralization in the dentifrice was nearly equal to that in the remineralized controls. Remineralization with the rinse was higher in the first and second layer (about 10-20μm depth) than that with the control and the dentifrice. The degree of remineralization for APF was the highest and the remineralization was evident from the surface to the bottom of the lesion area.