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PubMed2005

The effect of different desensitizing agents on initial demineralization of human root dentin.

OBJECTIVES: The aim of this study was to determine the caries-protective effect of 3 different desensitizing agents (Seal & Protect 2.0, D/Sense 2, and Gluma Desensitizer) on root dentin in vitro. METHOD AND MATERIALS: The root surfaces of 60 freshly extracted, caries-free human molars were used. After removing the cementum, the teeth were coated with an acid-resistant nail varnish, exposing 2 rectangular windows of 2 X 3 mm each on the root surface. One window served as an untreated control, and the other window was treated with 1 of the desensitizing agents. The specimens were randomly distributed among the following experimental groups: group A, D/Sense 2; group B, Seal & Protect 2.0; and group C, Gluma Desensitizer. Subsequently, all specimens were demineralized for 14 days with acidified gel (HEC, pH 4.8, 37 degrees C). Two dentinal slabs were cut from each window. The slabs were ground to a thickness of 80 microm and immersed in water. The demineralization depth was determined using a polarized light microscope. RESULTS: The nontreated control specimens showed lesions with a mean depth of 84.9 microm (+/- 6.0). In the specimens treated with the desensitizing agents, lesion depth was generally significantly reduced. Statistical analysis revealed significantly lower values for the specimens in group B in comparison with the others. CONCLUSION: Within the limitations of an in vitro investigation, it can be concluded that the demineralization of the root surface can be hampered by applying the desensitizing agents tested.

Analysis of Variance↗

PubMed1991

Remineralization and demineralization in situ from a triclosan/co-polymer/fluoride dentifrice.

An in situ study was conducted to evaluate the effect of a dentifrice containing 1100 ppm F (NaF) and triclosan, an anti-plaque agent, on remineralization of artificially-formed caries lesions in thin sections of human enamel. The thin sections were placed in mandibular partial dentures of 15 subjects and covered with a steel mesh to provide an area for plaque accumulation. The subjects brushed their teeth and dentures three times daily for two-week periods in a cross-over design, after which the specimens were removed and analyzed by quantitative microradiography for changes in mineral content. Results showed that lesions treated with the triclosan-fluoride product were remineralized 18.0 +/- 23.4% compared with 19.0 +/- 32.3% from a 1100-ppm F (NaF) positive control. Use of a placebo dentifrice resulted in 71.9% demineralization. The findings showed that triclosan neither enhanced nor interfered with the promotion of remineralization by fluoride.

Adult↗

PubMed1990

[Effects of Nd:YAG laser irradiation on acid resistance of defective rat enamel].

As Colchicine is an inhibitor of the function of microtubles, administration of it causes abnormal amelogenesis in the teeth of experimental animals. The purposes of this study were to characterize the defective rat enamel which was formed after a single administration of colchicine, and to examine the effects of Nd:YAG laser with continuous wave on the acid resistance of the defective enamel. The following results were obtained: 1) On about the 10th day after a single subcutaneous injection of colchicine with a dose of 1.5 mg/kg of body weight, the defective enamel was found on the incisor as white bands with rough surface. 2) The defective enamel had less resistance to the acid demineralization than that of normal enamel. 3) After irradiation of Nd:YAG laser with continuous wave, the defective enamel surface became smooth and the small defects on the enamel surface disappeared. 4) After irradiation of Nd:YAG laser, the resistant level of the defective enamel to the acid demineralization increased up to that of normal enamel. The results suggest that Nd:YAG laser irradiation on human teeth with hypomineralized enamel may be effective for the prevention of dental caries.

Amelogenesis↗

PubMed2000

Crystallographic analysis of demineralized human enamel treated by laser-irradiation or remineralization.

Crystallographic information on dental hard tissue is helpful in evaluating whether incipient caries that has received preventative treatments is resistant to subsequent attack. The aim here was to analyse crystallographically by means of high-resolution electron microscopy (HREM) demineralized human enamel that had been laser-irradiated or remineralized. Electron-microscopic observation identified a distinct layer at a depth of 100 nm in the demineralized and laser-irradiated enamel. The crystallinity in the shallower area was inferior to that in the deeper area. Comparison of the HREM findings from the deeper area with the data provided by the Joint Committee on Powdered Diffraction Standards revealed that the mineral in the demineralized and laser-irradiated enamel was either alpha- or beta-tricalcium phosphate, while that in the remineralized enamel was thought to be tetracalcium diphosphate monoxide.

Adolescent↗

PubMedDate not supplied

Influence of calcium phosphates added to mucin-based saliva substitutes on bovine dentin.

OBJECTIVES: Remineralization of dentin by mucin-containing saliva substitutes might be inhibited by sialic acids bound to mucin, which are known to complex calcium. Thus, the aim of this investigation was to evaluate the effects of various mucin-containing solutions, differing in calcium phosphate concentrations, to be used as saliva substitutes on demineralized bovine dentin in vitro. METHOD AND MATERIALS: Bovine specimens (153) were embedded in epoxy resin, polished (4,000 grit), and partly covered with nail varnish (control of sound dentin). After demineralization for 14 days (pH 5.5), the specimens (n = 9) were exposed to 14 mucin-based solutions (30 g/L) at 2 different pH values (5.5 or 6.5) and differing in saturation with respect to apatites. Two fluoride-free solutions and the commercially available saliva substitute Saliva Orthana(Orthana, Kastrup) served as controls. Differences in mineral loss (deltadeltaZ) and lesion depth (deltaLD) between the values prior to and after storage in the various solutions were evaluated from microradiographs of thin sections (100 microm). RESULTS: The general linear model revealed an almost significant dependency on calcium for deltadeltaZ (P = .050) and a significant dependency on calcium for deltaLD (P = .037). pH influenced deltadeltaZ significantly (P < .001), whereas deltaLD was not influenced significantly (P = .169). Neither deltadeltaZ (P = .475) nor deltaLD (P = .703) were influenced significantly by phosphate. CONCLUSION: Even with low concentrations of calcium and phosphates, mucin-based saliva substitutes are capable of inhibiting demineralization of bovine dentin, whereas with solutions supersaturated with respect to apatites, a remineralizing effect could be observed.

Analysis of Variance↗

PubMedDate not supplied

Effect of dentifrice containing fluoride and/or baking soda on enamel demineralization/remineralization: an in situ study.

The additive effect of baking soda on the anticariogenic effect of fluoride dentifrice is not well established. To evaluate it, a crossover in situ study was done in three phases of 28 days. Volunteers, using acrylic palatal appliances containing four human enamel blocks, two sound (to evaluate demineralization) and two with artificial caries lesions (to evaluate remineralization), took part in this study. During each phase, 10% sucrose solution was dripped (3 times a day) only onto the sound blocks. After 10 min, a slurry of placebo, fluoride (F) or fluoride and baking soda (F+NaHCO(3)) dentifrice was dripped onto all enamel blocks. The results showed a higher F concentration in dental plaque formed during treatment with F+NaHCO(3) than placebo (p<0.05), but the difference related to F dentifrice was not significant. The enamel demineralization was lower, and remineralization was greater, after treatment with F+NaHCO(3) than placebo (p<0.05), but the difference related to F dentifrice was not significant. The data suggest that baking soda neither improves nor impairs the effect of F dentifrice on reduction of demineralization and enhancement of remineralization of enamel.

Buffers↗

PubMed1991

A quantitative analysis of mineral loss and shrinkage of in vitro demineralized human root surfaces.

Demineralization of dentin specimens proceeds at a faster rate than that of enamel. Although this is generally accepted, a quantification of the rate of formation of root lesions is hampered by the shrinkage of the lesions when these are dried prior to microradiographic analysis. This leads to a significant underestimation of the lesion depth and total mineral loss. The aim of this paper was to quantitate the rate of mineral loss during root lesion formation in vitro and to determine the shrinkage of root specimens as a result of drying. Unerupted roots of human teeth were subjected to a demineralizing system of 0.1 mol/L lactate buffer (pH = 4.8) with 0.2 mmol/L methanehydroxydiphosphonate during four, 11, 22, and 44 days. The root lesions were assessed by quantitative microradiography. The demineralizing solutions were analyzed to determine the amounts of root tissue dissolved. A comparison of these two sets of data showed that, with the demineralizing system used, root lesions may shrink up to 62%. Fixation of the specimens in fixative did not affect this shrinkage. Chemical analysis showed that mineral loss proceeded linearly with time. From the data-sets of this study, a model was developed to compensate for the shrinkage in the dentin specimens. In this way, it was possible to calculate the lesion depth at four demineralization times as being 130, 220, 320, and 530 microns, respectively. These values were in agreement with a microscopic determination of the lesion depth.

Decalcification Technique↗

PubMed1993

Wound healing following demineralization of resected root ends in periradicular surgery.

The objective of this study was to determine the effect of demineralization of resected root ends on the temporal and qualitative healing of the dentoalveolar (apical attachment apparatus) and alveolar (osseous) tissues in the excisional wound site created during periradicular surgery. Root end resections to orthograde gutta-percha obturations were performed on the mandibular premolars of six mongrel dogs. Twenty-four experimental root ends were demineralized by citric acid burnishing of the resected surfaces. The remaining 24 standard treatment root ends were not demineralized. Microscopic evaluations at postsurgical intervals from 4 to 45 days revealed that the demineralized root ends were associated with more rapid and complete healing than the nondemineralized root ends. It is proposed that demineralization enhances cementogenesis, the key to dentoalveolar healing, by removing the smear layer barrier and exposing the organic component (collagen fibrils) of resected cementum and dentin.

Acid Etching, Dental↗

PubMed2006

Remineralized dentin lesions induced by glass ionomer demonstrate increased resistance to subsequent acid challenge.

OBJECTIVE: The purpose of this study was to test the hypothesis that remineralized dentin lesions induced by glass ionomer are less vulnerable to subsequent acid challenge. METHOD AND MATERIALS: Baseline demineralized (BDe) lesions were created in 50 bovine dentin slices immersed for 3 weeks in acid solution. A resin-modified glass ionomer (RMGI) was applied to the specimens before immersion in salivalike solution to allow remineralization (Re) for 2 weeks (V2W) or 6 weeks (V6W). Resin-modifed glass ionomer was coated to block further ion release before a 3-week immersion in acid solution as a second demineralization (SDe). Control groups (C2W and C6W) were done simultaneously without RMGI. In another group, RMGI was left undisturbed (V2W+) to allow continuous ion release during SDe. Mineral content was converted from microradiographs, after BDe, Re, and SDe steps. Changes in mineral content were calculated and compared between groups. RESULTS: The remineralized surface zone was maintained after SDe, but the lesion body became deeper. Percentage of mineral loss from SDe was not significantly different between V2W and C2W (t test, P > .05). When remineralization was extended to 6 weeks, V6W showed significantly less mineral loss than C6W. Mineral loss was lowest when RMGI was not blocked (V2W+). CONCLUSION: Dentin lesions remineralized in the presence of RMGI maintained the highly mineralized surface zone when subjected to second demineralization. However, the remineralized surface zone could not prevent advance of the lesion body. The subsequent demineralization was markedly reduced by extending the remineralization period or by leaving the RMGI undisturbed to resume ion release.

Acids↗

PubMed1991

Acid-susceptibility of lesions in bovine enamel after remineralization at different pH values and in the presence of different fluoride concentrations.

Artificial caries lesions were created in sound bovine enamel slices demineralized at pH 5.0. The lesions were then remineralized at either pH 5.5 or pH 6.8 in solutions containing either 1.5, 15, or 50 mumol/L fluoride. The remineralized slices were then demineralized at pH 5.0 for investigation of acid-susceptibility by means of quantitative microradiography. The results indicated that fluoride, incorporated during the preceding remineralization, had a retarding effect on the demineralization after remineralization, and that for the lowest concentration of fluoride in the remineralizing solution, the inhibitory influence of fluoride depended on the pH of the remineralization solutions used.

Acids↗

PubMed1998

Effect of toothpicks with and without fluoride on De- and remineralization of enamel and dentine in situ.

The aim of this investigation was to study the effect of the interproximal use of fluoride (F)-impregnated and non-impregnated birch toothpicks on the degree of de- and remineralization of enamel and dentine in situ. Ten volunteers with complete dentures in the upper jaw participated. Each subject had four specimens: (1) sound enamel, (2) demineralized enamel, (3) sound dentine and (4) demineralized dentine; placed pairwise at two approximal sites (15/16 and 25/26) of the maxillary prosthesis. The study involved three test periods (A, B and C), each lasting 4 weeks. In A, the subjects used F toothpicks (impregnated in 4% NaF) and, in B, nonimpregnated toothpicks 3 times daily. During period C, no toothpicks were used. Dentifrice or other F-containing products were not allowed during the 4-week periods. Transversal microradiography was used to determine lesion depth (ld) and mineral loss (DeltaZ). The results revealed that all the sound samples lost mineral during the three experimental periods; DeltaZ for both enamel and dentine was less for A and B compared with C (p<0.01) and less for A compared with B and C for dentine (p<0.05, p<0.01). The demineralized samples also lost mineral, apart from dentine, during periods A and B, i.e. when F-impregnated and non-impregnated toothpicks were used; ld for enamel and DeltaZ for dentine were less for A compared with C (p<0.05). Four weeks' use of toothpicks, especially F-impregnated toothpicks, thus reduces the demineralization of enamel and dentine at approximal sites in situ.

Aged↗

PubMedDate not supplied

Effect of a low-fluoride-content, two-component rinse on fluoride uptake and on de--and remineralization of enamel lesions: an in vitro study.

The effect of calcium (Ca) concentrations and added ethanol on fluoride (F) depositions by experimental two-component rinses, each consisting of a Ca-containing and an F-containing component, was evaluated in an in vitro system. Among the tested rinses, a 3 mmol/l F two-component rinse with 200 mmol/l Ca and 10% v/v ethanol was found to produce the greatest F deposition relative to the F concentration in the rinse. Specifically, this rinse produced an F deposition that was about 7 times greater than a conventional 13.2-mmol/l sodium fluoride (NaF) rinse. In a second experiment, an in vitro pH cycling model was used to evaluate the potential anti-caries effects of 4 rinses: (1) placebo rinse (no F), (2) 13.2-mmol/l NaF rinse, (3) 52.6-mmol/l NaF rinse, and (4) the 3-mmol/l F two-component rinse in a 7-day in vitro pH cycling model. The changes in lesion mineral contents, delta(DeltaZ), as assessed by quantitative microradiographic measurements, were as follows [mean +/- standard deviation, n = 10]: (1) 72.5+/-10.2 microm, (2) 43.4+/-5.6 microm, (3) 17.3+/-10.2 microm and (4) 45.3+/-5.2 microm. These results showed that the 3-mmol/l F two-component rinse produced the same (p>0.05) protection against demineralization as did the 13.2-mmol/l NaF rinse which had 4 times the fluoride content. The results suggest that it is possible to formulate an effective low-F two-component rinse.

Analysis of Variance↗

PubMed2000

Bond strengths of self-etching primer adhesives to in vitro-demineralized dentin following mineralizing treatment.

PURPOSE: The purpose of this study was to determine if treatment of experimentally demineralized dentin with a calcium phosphate precipitating (CPP) solution could restore the bond strength of self-etching adhesives to that of normal mineralized control values. MATERIALS AND METHODS: The occlusal surfaces of human teeth were exposed for bonding. The teeth were assigned to a mineralized control group or one of three demineralized (40% phosphoric acid for 60 s) experimental groups. One of the experimental groups remained untreated, while the other two were treated with the CPP solutions for either 1 or 10 min. All experimental groups were then chemically dehydrated with ascending acetone concentrations to prevent shrinkage prior to bonding with Clearfil Liner Bond 2 (LB2) or MacBond II (MBII). Composite buildups were made and vertically, serially sectioned into multiple slabs about 0.7 mm thick. Each slab was then trimmed for microtensile bond testing and SEM examination. RESULTS: Both self-etching adhesives produced high bond strengths to control mineralized dentin (ca 42 and 37 MPa for LB2 and MBII, respectively). Acid etching with 40% phosphoric acid for 60 s followed by chemical dehydration significantly lowered (p < 0.05) bond strength to 26 and 27 MPa for LB2 and MBII, respectively, and created hybrid layers between 7 and 8 microns thick. When the demineralized dentin was treated with the CPP solution for 1 min, the bond strengths increased (p < 0.05) to 39 for LB2 and 42 MPa for MBII, and the hybrid layers were 11 microns thick. Increasing the CPP treatment time to 10 min lowered (p < 0.05) bond strengths but increased the hybrid layer thickness to 16 to 20 microns. CONCLUSION: The use of calcium phosphate precipitating solutions may permit higher bond strengths of self-etching primers to demineralized (e.g., caries-affected) dentin.

Acid Etching, Dental↗

PubMed2001

[An experimental study on demineralization of several beverages on bovine enamel].

OBJECTIVE: The aim of this study is to investigate the demineralization effects of several beverages on bovine enamel. METHODS: The concentration of calcium and phosphate in these beverages were measured by using EL 312e Micro-Plate after the bovine enamel was exposed to beverages for a period of 7 days. RESULTS: The data indicated that almost all of these beverages could cause demineralization of bovine enamel, except mineral water, and the concentration of calcium and phosphate in these beverages changed after the bovine enamel was exposed to beverages. There were great significant differences in demineralization abilities among different beverages (P < 0.01). The concentration of calcium and phosphate in beverages also changed with time (P < 0.01). CONCLUSION: All these beverages, except mineral water have erosive effects on bovine enamel. Demineralization degree varied with kinds of beverages. The fruit juice has the highest erosive effect on the enamel, and the calcium milk has the lowest erosive effect on the bovine enamel, when comparing with other beverages.

Animals↗

PubMed1999

An in situ caries model to study demineralisation during fixed orthodontics.

OBJECTIVES: To investigate de/remineralization of enamel during the early stages of orthodontic treatment using the in situ caries model. DESIGN: A prospective, longitudinal study, using the in situ caries model. SETTING AND SAMPLE POPULATION: The Department of Orthodontics at the University of Liverpool School of Dentistry. Fifteen orthodontic patients undergoing fixed appliance treatment with extraction of premolar teeth. EXPERIMENTAL VARIABLE: Two enamel samples with pre-formed caries-like lesions were placed bilaterally, in specially constructed holders, on an orthodontic fixed appliance. One sample was bonded with a small bracket base. OUTCOME MEASURE: The parameters of the pre-formed carious lesion, expressed as mineral loss (delta Z), lesion depth (ld), lesion width (lw) and ratio (delta Z/ld) were compared between the bracketed, the non-bracketed and a control sample that had not been placed in the mouth. The difference between brackets place on the dominant (toothbrush hand) side and non-dominant side were also investigated. The correlation between mineral loss and length of time the sample was in the mouth was also analysed. RESULTS: There was considerable individual variation; however, a one-factor repeated analysis of variance showed a significant difference in ratio values between the three groups (p = 0.006). A pairwise comparison showed a significant reduction in ratio value for the non-bracketed sample compared with the control, but not the bracketed sample. There was no significant difference in mineral loss between the dominant and non-dominant sides. There was no linear correlation between the length of time the sample was in the mouth. CONCLUSION: An enamel sample with a pre-formed carious lesion, when placed in the mouth of an orthodontic patient, showed reduced remineralization in the presence of a simulated orthodontic bracket. Consistently effective preventive regimes to prevent demineralization in patients with fixed orthodontic appliances need to be developed. The technique described will be a valuable tool in this process.

Analysis of Variance↗

PubMed2002

Effect of demineralization and remineralization on microhardness of irradiated dentin.

The aim of this in vitro study was to evaluate the effects of irradiation and fluoridation on the demineralization and remineralization patterns of root dentin. From the cervical regions of 84 bovine incisors, each of four dentinal blocks were prepared and randomly assigned to four groups: 1) no irradiation; 2) irradiation of specimens up to 60 Gy (2 Gy/d, 5 d/w); 3) no irradiation, but fluoridation of specimens for 5 min/d with Elmex Gelée; and 4) irradiation and daily fluoridation of specimens for 5 min/d. Subsequently, the specimens were demineralized for 2, 4, 6 or 8 days with acidulated hydroxyethylcellulose (n = 21), and Knoop hardness numbers (KHN) were determined before, as well as after the demineralization period. Then seven specimens from each group were fluoridated with one of three fluoride gels (Elmex Gelée [1.25%], STOP [0.4%], Fluoridgel [1.25%]; 2 x 15 min/d, 10 d), and immersed in synthetic saliva at a temperature of 37 degrees C. Finally, KHN for all specimens were determined. Irradiation resulted in a significant decrease in microhardness. There was a reduction in microhardness with increasing demineralization time in all groups. The highest percentage decrease in microhardness could be observed with group 1. Due to the preceding decrease of KHN in the irradiated specimens (group 2), these samples showed less percentage reduction in microhardness during demineralization when compared to group 1 (ANOVA; p < 0.001). The decrease in microhardness was significantly hampered by fluoridation in the non-irradiated, as well as in the irradiated samples (groups 3 and 4; p < 0.001). The remineralization with Fluoridgel resulted in the greatest increase in microhardness. It is concluded that demineralization can be hampered by regular fluoride application in irradiated dentin. However, due to the considerable irradiation effect, this benefit might be negligible.

Amines↗

PubMed1996

Determination of fluoride from fluoride-releasing elastomeric ligature ties.

Unaesthetic white spot lesions or larger unsightly areas of decalcification around orthodontic brackets remain a significant problem during fixed appliance treatment. This study determined the in vitro fluoride release from 200 fluoride-containing elastomeric ligature ties. With the potentiometric analytic method, the fluoride release was determined in distilled water, for 10 groups of 20 elastomerics, representing the clinical usage in a patient. Readings were taken every 24 hours for 5 days and then every second week for 6 months. The data were analyzed with the Wilcoxon matched pairs signed ranks test. Fluor-I-Ties (Ortho Arch Company Inc., Hoffman Estates, III.) released significant amounts of fluoride compared with the control readings. The fluoride release was characterized by an initial burst of fluoride during the first day and second day, followed by a logarithmic decrease. By the end of the second week 88% of the total fluoride had been leached from the elastomerics, but adequate magnitudes of fluoride were released over the remainder of the test period to aid theoretically in the prevention of demineralization and enhance remineralization of enamel through calcium fluoride and fluorapatite formation. For optimum clinical benefit, Fluor-I-Ties should be replaced monthly. Future prospective longitudinal clinical studies are indicated.

Apatites↗

PubMedDate not supplied

Susceptibility of enamel surfaces to demineralization after application of fluoridated carbamide peroxide gels.

The aim of the present study was to evaluate the effect of experimental, fluoridated carbamide peroxide gels on formation of erosively induced demineralization of enamel. Seventy-five bovine enamel specimens were polished for microhardness determination and evenly distributed among 5 groups (A-E). The specimens were treated with 10% carbamide peroxide gel (8 h) and subjected twice to remineralization for 2 h in artificial saliva and demineralisation for 90 s in 1% citric acid, pH 2.2. The cycles of treatment with carbamide peroxide and twofold re- and demineralization were repeated three times. The carbamide peroxide gels were different in pH and fluoride content. Gel A (pH 7.0) and gel B (pH 5.7) were fluoridated (0.5% F), gel C (pH 7.0) and gel D (pH 5.7) were not fluoridated. In control group E the samples were not treated with a gel, but stored in 100% humidity for 8 h instead. Knoop microhardness of the specimens was assessed directly after polishing, and after each carbamide peroxide treatment and demineralization. All specimens showed a loss of microhardness at the end of the experiment. After 3 days, the controls revealed a significantly lower hardness loss compared to the specimens treated with the carbamide peroxide gels. Surface softening was significantly lower for the specimens of group A compared to the remaining groups (B-D), which were not significantly different among each other. It is concluded that treatment with either fluoridated or unfluoridated carbamide peroxide gels, at either neutral and acidic pH, renders enamel more susceptible to demineralization. Use of a fluoridated neutral gel decreases the degree of surface softening compared to the other gels investigated.

Analysis of Variance↗