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PubMed2003

Influence of salivary pellicle formation time on enamel demineralization--an in situ pilot study.

This study assessed the protective potential of salivary pellicles formed in situ over periods ranging from 2 to 24 h. Pellicles were produced on enamel slabs mounted on the palatal aspect of removable acrylic splints and exposed to the oral environment in three subjects for 2, 6, 12 and 24 h. Enamel specimens with and without pellicles were immersed in citric acid (1%) for 60 s, and the amount of dissolved calcium was measured by atomic absorption spectroscopy. In addition, specimens were processed for transmission electron microscopy (TEM). Mean values (standard deviations) for calcium release (mg/l related to the specimen's surface area of 5 x 5 mm(2)) were: 2-h pellicle 6.94 (1.55); 6-h pellicle 6.69 (2.05); 12-h pellicle 6.57 (2.31); 24-h pellicle 5.71 (2.46); enamel without pellicle 8.95 (1.66). There were no significant differences in calcium release that were dependent on pellicle formation time, but in comparison to enamel specimens without pellicle, significantly less (p <0.05) demineralization of the enamel was observed in pellicle-covered specimens. TEM showed that the pellicle was partly, but not completely dissolved following acid exposure. It is concluded that even a 2-h in-situ-formed pellicle layer protects the enamel surface to a certain extent against demineralization.

Analysis of Variance↗

PubMed2006

Effects of irradiation on in situ remineralization of human and bovine enamel demineralized in vitro.

The objective of this study was to evaluate the effects of irradiation and surface condition on in situ remineralization of demineralized human and bovine enamel. Specimens (n=96) obtained from 24 human molars and 24 bovine incisors were prepared. The surfaces of half of the specimens were abraded while the others remained natural. Each of the 12 human and bovine abraded and sound specimens was irradiated fractionally up to 46.5 Gy (3.1 Gy/day, 5 days/week), while the remaining samples were not irradiated. Prior to and following the demineralization (pH 5.0; 14 days) all specimens were partly covered with nail varnish (control). After in vitro demineralization 2 irradiated and 2 nonirradiated specimens were inserted into both buccal aspects of 12 intraoral appliances, which were worn by 12 persons for a period of 6 weeks. All samples were brushed twice a day with a fluoride-containing toothpaste. Mineral analyses revealed a significant influence on mineral loss (DeltaZdemin), mineral gain (DeltaDeltaZ), lesion depth (LDdemin), and lesion depth reduction (DeltaLD) of the variables 'material' and 'irradiation' (p<0.05; ANOVA). Reciprocal interactions could be observed between these two variables for DeltaZdemin, DeltaDeltaZ, and LDdemin, due to significantly reduced values found for the irradiated, abraded bovine specimens compared to the nonirradiated ones (p<0.05; Bonferroni post hoc test). It can be concluded that neither irradiation nor abrasion influenced in vitro demineralization or in situ remineralization of the human specimens, whereas abrasion hampered demineralization in irradiated, bovine specimens.

Adult↗

PubMed1992

Acid-susceptibility of lesions in bovine enamel after remineralization in the presence of fluoride and/or carbonate.

After de- and subsequent remineralization at 0.03 and 1.0 ppm fluoride and either 0, 1, 10, 20 or 25 mM carbonate, artificial lesions in bovine enamel were demineralized again. The amount of secondary demineralization was determined after 15, 30 and 70 h of demineralization by means of quantitative microradiography. The results showed that fluoride incorporated during the remineralization period retards lesion formation during secondary demineralization. Carbonate incorporated during the remineralization period enhances secondary demineralization. An interaction between both ions was observed.

Animals↗

PubMed2004

The continuum of dental caries--evidence for a dynamic disease process.

The eventual outcome of dental caries is determined by the dynamic balance between pathological factors that lead to demineralization and protective factors that lead to remineralization. Pathological factors include acidogenic bacteria, inhibition of salivary function, and frequency of ingestion of fermentable carbohydrates. Protective factors include salivary flow, numerous salivary components, antibacterials (both natural and applied), fluoride from extrinsic sources, and selected dietary components. Intervention in the caries process can occur at any stage, either naturally or by the insertion of some procedure or treatment. Dental caries covers the continuum from the first atomic level of demineralization, through the initial enamel or root lesion, through dentinal involvement, to eventual cavitation. The dynamic balance between demineralization and remineralization determines the end result. The disease is reversible, if detected early enough. Since demineralization can be quantified at early stages, before frank cavitation, intervention methods can be tested by short-term clinical trials.

Cariostatic Agents↗

PubMed1995

Effect of low levels of fluoride on calcium uptake by demineralized human enamel.

The effect of fluoride (ca. 0.1 parts/10(6)) on calcium uptake by enamel was examined under alternating remineralizing and demineralizing conditions. The remineralizing solutions contained either 0, 0.058, 0.104, or 0.138 parts/10(6) fluoride (ex NaF), while the demineralizing solutions contained no added fluoride. During the demineralization periods, calcium loss was similar for all groups. However, during the remineralizing periods, all levels of added fluoride were found to promote calcium uptake. Calcium levels taken up by the artificial lesions were sound to increase with increasing fluoride concentration in solution, and were independent of surface area of exposed enamel. In the absence of fluoride, even under conditions that are considered to be remineralizing, further demineralization took place.

Calcium↗

PubMed1995

pH-cycling of enamel and dentin lesions in the presence of low concentrations of fluoride.

F-dentifrice usage causes slightly elevated fluoride levels in saliva. Therefore, the effects of permanent low fluoride concentrations versus daily dentifrice treatments were studied on enamel and dentin lesions in a pH-cycling model of alternating demineralization and remineralization. Groups received 1) no fluoride treatment, 2) 3 mu M (0.06 ppm) F continuously present during re- and demineralization or 3) daily 5-min F-dentifrice treatments. Solutions were analyzed for changes in calcium and fluoride. Cumulative results (10 d) showed that for the non-fluoride group the dentin lesions increased, while for enamel lesions mineral uptake and loss were balanced. Addition of 3 mu M F caused small, non-significant, enhancement of remineralization (1-7%), while demineralization was significantly inhibited for both tissues (9-23%). The daily dentifrice treatments resulted in a balance between mineral uptake and loss of dentin, due to inhibited demineralization (-33%) and enhanced remineralization (+79%). For enamel, the F-dentifrice treatments resulted in 43% reduction of demineralization, with no significant effect on remineralization. Fluoride loss from the 3 mu M F cycling solutions was significant (up to 50%) and constant during the experimental period. Microradiographic analysis showed remineralization at the lesion front in enamel. In dentin, the lesion depth was increased in all groups, with concomitant mineral deposition in the surface region of the dentifrice group. Results indicate that slightly elevated fluoride levels may be considerably less effective in inhibiting lesion progression in dentin than in enamel, and suggest mineral uptake and loss to occur at similar depths for enamel lesions, while demineralization and remineralization occur at different depths in dentin.

Animals↗

PubMed1994

The influence of the organic matrix on demineralization of bovine root dentin in vitro.

The effect of matrix degradation on the rate of demineralization of dentin lesions was investigated. It was hypothesized that the demineralized matrix would inhibit the demineralization of the underlying mineralized dentin. Bovine root dentin specimens were alternately demineralized and incubated with either a bacterial collagenase or buffer (control). The demineralization was carried out under various conditions: Acetic acid solutions were used to form incipient and advanced erosive lesions, and lactic acid solutions containing a bisphosphonate were used to form incipient subsurface lesions. Under all conditions, the demineralization was found to be accelerated when the matrix was degraded by collagenase. This increase was more pronounced in advanced erosive lesions than in incipient lesions. Microscopic examination of collagenase-treated specimens revealed that the matrix of erosive lesions contained several layers of differently affected matrices, whereas the matrix of subsurface lesions appeared to be equally affected throughout the lesion. In conclusion, the matrix degradation was different in erosive and subsurface lesions but promoted the demineralization in both types of lesions.

Acetates↗

PubMedDate not supplied

Comparative in vitro microradiographic effects of resin-modified and autopolymerizing glass ionomers on demineralization of primary and permanent enamel.

The purpose of this study was to compare in vitro effects of resin-modified and autopolymerizing glass ionomer restorative materials on demineralization of primary and permanent human enamel. Thirty primary and permanent enamel specimens measuring approximately 3 x 4 x 4 mm were sectioned and plano-paralleled before random placement of materials: Photac-Fil, a resin-modified glass ionomer; Ketac-Fil, an autopolymerizing glass ionomer; and Tytin, a silver amalgam. After incubation for twenty-four hours, the samples were pH cycled for eight hours at pH 5.0 and sixteen hours at pH 7.2 for a total of two weeks, all at 37 degrees C. The specimens were then subjected to an artificial caries challenge at pH 5.0 for 196 hours. The specimens were embeded in Epon 812 and incubated at 55 degrees C for thirty-six hours. Microsections were produced from each sample and subjected to microradiography and quantitative microdensitometry. Data on lesion depth and mineral content were analyzed by Two Way ANOVA and Student Newman-Keuls Pairwise Multiple Comparison tests. There were significant differences in lesion depth and mineral content between groups (p < 0.05) and between permanent and primary enamel. This study demonstrates that Photac-Fil and Ketac-Fil prevent in vitro demineralization at varying levels in primary and permanent enamel.

Absorptiometry, Photon↗

PubMed2005

Healing of dehiscence defects following root surface demineralization with tetracycline: a histologic study in monkeys.

BACKGROUND: The purpose of this study was to histologically evaluate the healing of experimental dehiscence defects after surface demineralization with tetracycline hydrochloride. METHODS: Six adult male monkeys (Cebus apella) were used in this study. Dehiscence defects were surgically created on the buccal aspect of the mandibular lateral incisors in all animals. The root surfaces were debrided and planed. In a split-mouth design, a 10% tetracycline hydrochloride solution was applied to one tooth for 4 minutes (T group), followed by irrigation with saline. The contralateral tooth served as a control (C group). The flaps were repositioned and sutured. The animals were sacrificed at 6 months postoperatively and histological sections were processed. Computer-assisted histomorphometric analysis was used to evaluate the formation of new cementum, new bone, new connective tissue attachment, and length of the epithelium (junctional and sulcular). RESULTS: Bone regeneration was similar in both groups (1.5 +/- 0.3 mm for the T group and 1.5 +/- 0.6 mm for the C group). The C group showed more new cementum than the T group (2.3 +/- 0.3 mm versus 2.2 +/- 0.3 mm) as well as a longer epithelium (1.0 +/- 0.3 mm versus 0.9 +/- 0.2 mm). The T group presented more new connective tissue attachment (3.1 +/- 0.2 mm) than the C group (2.9 +/- 0.6 mm). However, no statistically significant differences were detected between the two groups. CONCLUSIONS: The amount of new attachment was similar in both groups. Root conditioning with 10% tetracycline solution did not produce any additional new attachment in comparison to the controls.

Animals↗

PubMed1999

Effect of high fluoride concentration on bovine dentin demineralization in narrow grooves in vitro.

Previously, a dentin groove model was developed to investigate caries at plaque retention sites, such as marginal gaps, and pits and fissures. The aim of the present study was to investigate the in vitro effect of fluoride on the demineralization of dentin in the depth of the grooves at various distances from a freshly prepared resin-modified glass ionomer cement (RMGIC), which was used as the source of high fluoride release. Three parallel grooves (280 microm wide x 500 microm deep) were cut in the labial surface of 20 bovine coronal dentin discs. In 10 discs, the surface area (approximately 6 mm2) between the first groove and the edge of the disc was covered with RMGIC. The discs were exposed to an acidified methylcellulose gel system for 1 or 2 wk. Changes in mineral content were obtained by transverse microradiographic analysis. The results showed that integrated mineral loss (IML) was reduced up to 60% in the RMGIC groups, although the lesion depth was not significantly influenced by RMGIC. The pattern of demineralization differed between groups: the subsurface lesions in RMGIC groups did not decrease in IML towards the base of the groove to the same degree as in the control groups. It is concluded that high amount of fluoride inhibits loss of mineral, while not affecting the lesion depth. The homogeneity of the lesions with depth in the RMGIC group may be explained by a fluoride-induced inhibition of demineralization at the entrance of the grooves.

Analysis of Variance↗

PubMed2002

Studies on dental erosion: An in vivo-in vitro model of endogenous dental erosion--its application to testing protection by fluoride gel application.

BACKGROUND: The objective in this study was to develop an in vivo-in vitro model of endogenous erosion, with a view to exploring the potential for some degree of its control by the use of topical fluoride gel application to teeth. METHODS: Six volunteers each wore a small clasp retained palatal acrylic appliance to which six sterilized enamel tiles were bonded. Three tiles on each appliance were coated extra-orally with either 1.23 per cent acidulated phosphate fluoride (APF) or 2.2 per cent sodium fluoride (NaF) neutral gel for four minutes prior to multiple periods of exposure to the simulated gastric acid, cumulating in 16, 36, 80 and 150 minutes of exposure. Impressions of the enamel tiles prior to and following acid exposure permitted dies to be prepared. These were sectioned through the exposed areas and examined under a stereomicroscope to assess maximum depths of erosion. RESULTS: The depth of erosive demineralization of enamel was found to be greatly reduced with increased frequency of APF gel application. The reduction in enamel loss was less following topical application of NaF gel. CONCLUSIONS: It was concluded that fluoride gels significantly reduced enamel erosion using this in vivo-in vitro model and therefore, if prescribed appropriately, should help reduce tooth tissue loss from endogenous erosion.

Acidulated Phosphate Fluoride↗

PubMed1988

Abrasion biopsy in studies of mineral density of experimental enamel lesions.

The profile of mineral density of experimental enamel lesions was determined by means of sampling with a new abrasion biopsy technique. Three types of lesions were produced on bovine enamel slabs: (1) pre-softened in lactic acid buffer for 16 hr; (2) pre-softened and exposed to a test for acid resistance for seven days; and (3) pre-softened, exposed to the seven-day Intra-oral Cariogenicity Test with extra-oral immersions in 1000 ppm F solutions for one min twice daily (ICT/F), plus the seven-day test for acid resistance. Lesions were assessed with measurements of surface microhardness, microradiography of thin sections, and abrasion biopsy. For abrasion biopsy of the experimental lesions, 15 parallel layers of approximately 10 microns each were abraded simultaneously with reference slabs of sound enamel on strips of lapping film. The depth of abrasion for each sample was calculated from the phosphorus content of the reference sample. Exposure to the ICT/F formed an acid-resistant zone within the lesion which diminished the microhardness change, although it did not have an appreciable effect on the total lesion depth as assessed with microradiography; abrasion biopsy indicated the formation of a mineral-dense zone within the lesion. This recently-developed technique of abrasion biopsy of experimental lesions offers the opportunity to link the composition of the lesion to controlled experimental conditions which will improve our understanding of demineralizing and remineralizing reactions on a standard tooth substrate.

Animals↗

PubMed1992

Multifactorial modeling for root caries prediction.

The study was part of a series of investigations aiming at the development of diagnostic caries tests for screening of risk subjects. The material consisted of 100 adult subjects (mean 62 yr, range 47-79 yr), 50 of these under chronic medication. The series of tests included two chairside registrations, i.e. incipient demineralization of exposed root surfaces without cavitation (RD 1) and quantitation of visible plaque (VPT%), three microbiological tests for mutans streptococci, lactobacilli, and candida/yeasts and three tests on stimulated saliva, i.e. secretion rate, buffering capacity and sucrase activity. A thorough clinical examination was conducted at the baseline and 1-yr registration phases, caries being registered at a tooth surface level according to WHO recommendations separately for coronal and root caries. Considerably more root caries than coronal caries developed during the observation period. For coronal caries increment, the predictive value of any of the tests was not significant. For root caries, however, the association between several tests and prospective caries increment was significant. Subsequent multifactorial modeling yielded the highest predictive value to the combination of Past Root Caries Experience (OR 25.0, Visible Plaque (OR 4.2), Candida (OR 8.0) and Lactobacilli (OR 5.8). A positive finding of Past Root Caries (RDFS) or the combination of the other three tests (Can, LB, VPT%) as criteria for selection in screening for root caries produced good accuracy (84.0) and a relative risk of 5.5.

Aged↗

PubMed1991

Effect of 2-O-stearoyl glycerol-1,3-bisphosphate on in vitro demineralization of dental root surfaces.

The effect of 2-O-stearoyl glycerol-1,3-bisphosphate (Glydip) on caries lesion formation in root surfaces of sound human third molars was investigated in vitro. For this purpose parts of the root surfaces were treated with Glydip. Adjacent parts of the surfaces were not treated and served as control. Lesions were obtained by demineralization with an acetate buffer of pH 5.0. It was found that Glydip had no inhibiting effect on the rate of lesion formation. Additionally, pretreatments were performed with lauryl sulphate, a chloroform-methanol mixture, an aqueous solution of sodium hypochlorite, and collagenase prior to the treatment with Glydip to enhance the accessibility of the tissue for Glydip. None of these pretreatments or combinations of them revealed an inhibiting effect of Glydip on the rate of caries lesion formation. This result is in contrast to the effect of Glydip on the demineralization of enamel.

Acid Etching, Dental↗

PubMed2006

Laser-fluoride effect on root demineralization.

Although the individual cariostatic effects of laser and fluoride have been shown, the combined effect of CO(2) laser and fluoride on root demineralization remains uncertain and was the main aim of this study. By using a pH-cycling system and Polarized Light Microscopy, we demonstrated the synergistic effect of fluoride combined with CO(2) laser treatment on reducing root demineralization. The mean lesion depths (in microm) for each group were 160 +/- 14 (Control), 113 +/- 8 (Laser treatment alone), 111 +/- 6 (Fluoride treatment alone), and 25 +/- 7 (Fluoride followed by laser treatment). A significant laser-enhanced fluoride uptake, characterized by the ToF-SIMS analysis, was revealed by the 37% and 400% increments in loosely and firmly bound fluorides (both p < 0.002) in laser-irradiated areas, compared with the non-irradiated controls. In conclusion, there is a significant synergistic effect of combined CO(2) laser and fluoride treatment on the inhibition of root demineralization, possibly due to laser-enhanced fluoride uptake in the root.

Carbon Dioxide↗

PubMed2004

Effect of diode laser and fluoride varnish on initial surface demineralization of primary dentition enamel: an in vitro study.

INTRODUCTION: Previous investigations have demonstrated improved enamel caries resistance after laser irradiation. The purpose of this in vitro study was to assess the caries-preventive potential of 809 nm diode laser treatment of the enamel of primary teeth compared to topical fluoride application. METHODS: Eighty samples of sound primary teeth were embedded in plastic and stored in saline solution. The enamel surface of 80 samples was polished in an area of 2 x 2 mm. These tooth specimens were randomly assigned to one control and three test groups: (1) no treatment/control; (2) application of 0.1 mg of fluoride varnish (Duraphat) for 6 h; (3) diode laser application (809 nm, 140 mJ, 50 Hz, Ø 600 micro m fibre, contact mode, absorber, 1 min; ORA-LASER01 I.S.T.); and (4) combined application - laser/fluoride varnish. Caries-like lesions were created by pH-cycling. After lesion formation, longitudinal sections were taken and examined by polarized light microscopy. RESULTS: In the control group, all samples showed lesions up to 30 micro m in depth. After laser application, lesions could be identified in 15 out of 20 samples. Topical fluoride treatment in groups 2 (varnish) and 4 (laser/varnish) completely inhibited the development of caries-like lesions in all samples. CONCLUSION: In this in vitro investigation, topical fluoride treatment enhances the resistance of sound enamel of primary teeth more effectively than diode laser application.

Chi-Square Distribution↗

PubMed1992

Remineralization of etched dentin.

To simulate a clinical cavity wall with the inner layer of carious dentin preserved, an artificially demineralized layer was made on the axial wall class V cavities of monkeys by a quick decalcifying solution. The cavities were then restored with a chemically adhesive composite resin after etching with a 40% phosphoric acid jelly etchant. Comparison of the Knoop hardness, the calcium concentration, and the scanning electron microscope observation of the dentin at the axial wall revealed that the dentin, demineralized by etching, was completely remineralized after 4 months.

Acid Etching, Dental↗

PubMed2003

The influence of a matrix metalloproteinase on the remineralization of artificially demineralized dentin.

PURPOSE: This investigation aimed at determining whether a collagenolytic matrix metalloproteinase (MMP-8) present in the oral fluids might attack demineralized dentin and thereby affect the potential for remineralization. MATERIALS AND METHODS: Dentin specimens from freshly extracted third molars were demineralized for 14 days in vitro and then remineralized for 7 days in the presence or absence of activated MMP-8. Following treatment the mineral level of the specimens was assessed from the outer dentinal surface using Electron Probe Micro Analysis (EPMA). RESULTS: The findings suggested that the addition of activated MMP-8 to the remineralizing solution led to reduced remineralization in the surface of the dentin. There appeared to be no effect on the remineralization from any dentin bound MMP activity. CONCLUSION: It appears that MMP-8 may negatively influence the remineralization of demineralized dentin.

Acetates↗