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PubMed1994

In situ remineralization of root surface lesions using a fluoride chewing gum or fluoride-releasing device.

The in situ remineralization of early root surface lesions was studied using a fluoride-releasing device (FRD) or a fluoride chewing gum. Root specimens with subsurface lesions were mounted in removable lower appliances in 6 adult subjects. Test groups chewed five sticks/day (0.1 mg F/stick) or one FRD (0.5 mg F/day release rate) was mounted in the midline of the appliance. A fluoride-free dentifrice was used three times/day for each 21-day control and the two test regimens. Separate root lesions were used to measure fluoride uptake or changes in mineral content by quantitative microradiography. Comparable values for percent remineralization for both FRDs and F gum were higher than controls, and the F uptake for FRDs exceeded both the F gum and controls (p = 0.05).

Adult↗
PubMed1995

Comparisons of in vitro root caries models.

The purpose of this article is to compare various model systems for the production of in vitro root caries and to assess their ability to simulate the naturally occurring root caries process. Partially saturated buffer models and gel models were evaluated using polarized light microscopy and both qualitative and quantitative microradiography. All model systems showed very similar lesion formation when examined under polarized light. When microradiographs were compared, the systems which contained fluoride, showed clear radiopaque bands within the lesion. The bands, which occurred only in the presence of fluoride, appeared to be due to remineralization. When using an in vitro system that simulates the natural root caries process, it is imperative to understand the components of the particular model, as well as its limitations, and to be aware of the need for more than one evaluative technique.

Buffers↗
PubMed1995

Effect of post-brushing water rinsing on caries-like lesions at approximal and buccal sites.

The aim was to study the effect of two different water rinsing procedures after toothbrushing with an NaF-containing dentifrice on the degree of de- or remineralization of enamel and dentine at approximal and buccal sites. Seven adults, wearing complete dentures, participated in two experimental periods (A and B) in a randomised order. During period A, they brushed with the dentifrice for 2 min, followed by 1-min active mouthrinse with the toothpaste-foam combined with 10 ml of water. No more water was used after the slurry had been spat out. During period B, the brushing was followed by 3 thorough rinsings of approximately 15 ml water each. These two procedures were carried out twice daily, i.e. in the morning (after breakfast) and in the evening (just before bedtime), during 3 months. Demineralized enamel and dentine samples were mounted at two locations--approximally and buccally--in the first molar region of the upper prostheses. Quantitative microradiography (TMR) was used to assess the lesion depth (ld) and the mineral loss (delta Z). The results showed that the approximally located samples continued to lose mineral during both periods A and B. However, the ld and delta Z values for enamel (p < 0.01) and dentine (p < 0.05) increased less during A than B. The buccally located enamel and dentine samples remineralized during the experiment, but no statistically significant differences were found for the ld and delta Z values of either enamel or dentine between periods A and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1996

The influence of mineral loss on the auto-fluorescent behaviour of in vitro demineralised dentine.

The aim of this study is to investigate the influence of demineralisation on the fluorescent properties of dentine. The fluorescence emission at 529 nm due to 515 nm excitation of in vitro demineralised lesions was determined with a micro-Raman spectroscope as a function of location. Results were compared with the mineral loss profiles of the same lesions measured by microradiography. The root surfaces of 6 in vitro demineralised human third molars (lactic acid CMC gel, pH 5; six groups: 0, 4, 7, 14, 18 and 21 days) were used in the experiment. Thin slices of +/- 130 microns were cut perpendicular to the tooth axis. The fluorescence scans corresponded to mineral loss profiles. Confocal microscope images showed increasing fluorescence with increasing mineral loss. From these results it is concluded that this mineral loss causes an increase in auto-fluorescence by a factor of at least 10, therefore the chromophore causing this green fluorescence must be organic in nature. De-quenching or modification of this fluorophore due to the demineralisation process is probably the cause for the increase of the green fluorescence.

Dentin↗
PubMed1996

Effect of sodium hypochlorite treatment on remineralization of human root dentine in vitro.

Dentine consists simplified of mineral and of several organic components. Sodium hypochlorite (NaOCl) is a well-known nonspecific proteolytic agent capable to remove organic material. The aim of this study was to investigate the influence of organic material removal from artificial dentine lesions by means of NaOCl pretreatment on subsequent remineralization with and without fluoride. Human root dentine samples were demineralized in an acidic gel (pH = 5) at 37 degrees C for 2 weeks. After 2 min of pretreatment with a 0.4, 2 or 10% NaOCl solution, the samples were remineralized in a 20 mM HEPES buffer (pH = 7) containing 1.5 mM Ca(2) and 0.9 mM phosphate with or without addition of 10 ppm F(-) as NaF at 37 degrees C for 8 days. Mineral profiles were assessed by means of transversal microradiography after diol treatment to avoid shrinkage caused by drying. In a separate experiments the dentine contraction caused by 10% NaOCl was assessed. The contraction (negligible for sound dentine) was found to be about 12% for the lesions. The remineralization results showed that pretreatment with a 10% NaOCl solution for 2 min, increased lesion remineralization. After NaOCl treatment, the amount of accumulated mineral increased by about 27% without F in the remineralization solution, and by about 4% with 10 ppm in solution. The in vitro results suggest that removal of organic materials from dentine lesions is an interesting approach to enhance remineralization.

Adolescent↗
PubMed1996

Demineralization of dentine grooves in vitro.

Caries mainly occurs at retention sites for plaque such as pits, fissures, margins of restorations and interproximal sites. An in vitro model was developed to investigate dentine caries in narrow gaps. Forty bovine coronal dentine discs were covered with bonding agent. In 20 discs, two grooves, 200 and 340 mu m wide and 500 mu m deep, were sawn to mimic fissures. In the 20 other discs, a 1-mm-wide groove was made and, after polyester sheets were placed against both walls, filled with composite. After curing of the composite and removal of the sheets, grooves of 22 mu m remained at the borders of the restoration. All grooves were exposed to 8% methylcellulose gel 0.1 M lactic acid at pH 4.8 for 1 week. Demineralization was determined by microradiography of sections sawn out of the center of the discs. The walls of the grooves showed subsurface lesions, which decreased in size towards the base of the grooves. The average mineral losses (vol % x mu m) at the entrance of the 22-, 200- and 340-mu m-wide grooves were 1,112 (SD 370), 1,277 (293) and 1,277 (255), halfway down the groove 218 (150), 659 (244) and 797 (207) and at the base of the groove 140 (88), 285 (145) and 504 (205), respectively. Analysis of variance and Tukey's B test showed that the average mineral losses from grooves of different width and from sites at different depth were all significantly different at p<0.05 level, but not for the mineral losses from the entrance of the two wider grooves and from the two lower sites in the narrowest groove. The reduced mineral loss in the two narrower groove widths is assumed to be caused by the more limited inward diffusion of acids and outward diffusion of mineral ions through the methylcellulose gel.

Analysis of Variance↗
PubMed1997

Relative ability of laser fluorescence techniques to quantitate early mineral loss in vitro.

This in vitro investigation was undertaken to explore two different nondestructive methods to detect very early demineralization. These methods were based on the premise that the clinical detection of caries at a very early stage of formation might permit more efficient reversal of the caries process than may occur when lesions are detected at a more advanced stage, such as a so-called 'white spot'. The methods evaluated in this study were quantitative laser fluorescence (QLF) and an experimental dye-enhanced laser fluorescence (DELF) technique. Prepared and polished bovine enamel specimens were demineralized in a conventional lactic acid-Carbopol solution for varying periods of time between 0 and 24 h with an area of sound enamel retained on each specimen. The coded and randomized specimens were then analyzed for the presence and severity of enamel demineralization using QLF after which they were exposed to a selected dye (Pyrromethene 556) and similarly examined using DELF. The specimens were then sectioned and examined by conventional transverse microradiography and by confocal laser-scanning microscopy. Results were analyzed statistically with sensitivity and specificity determined using sound enamel as the reference. The results indicated that QLF could detect demineralization which occurred as a result of 8 h exposure to the decalcification solution and was able to quantify changes in lesion severity associated with longer demineralization. While DELF was capable of detecting enamel demineralization after only 2 h exposure to the decalcification solution, it was unable to quantify increasing amounts of demineralization associated with longer periods of exposure to the decalcification solution. In summary, while DELF was able to detect very early demineralization, only QLF was capable of detecting and quantifying changes in the extent of the decalcification occurring with demineralization periods up to 24 h.

Animals↗
PubMed1997

Laser fluorescence quantification of remineralisation in situ of incipient enamel lesions: influence of fluoride supplements.

The aims of this study were to test the laser fluorescence method for quantification of remineralisation in situ of enamel with incipient lesions and to evaluate the enhancement of remineralisation by fluoride (F) supplements when a F dentifrice was used on a regular basis by healthy young subjects. Enamel samples were cut from extracted premolar teeth with the natural surface kept intact, and subjected to a pH-cycling system to produce subsurface demineralisation in vitro. The enamel blocks were then inserted into composite holders bonded to the buccal surfaces of both upper first molars of 12 panelists. Each panelist participated in 3 separate experiments in a randomised order; each lasted for 5 weeks with washout intervals of 2 weeks between experiments; experiment 1: F dentifrice (0.145% F as NaF) only; experiment 2: F dentrifice + F lozenges (0.25 mg F x 6/day); experiment 3: F dentifrice + F chewing-gum (0.25 mg F x 6/day). Fluorescence radiance was measured before, during, and after in vitro demineralisation, and once a week during the in situ experimental periods. The enamel samples were then sectioned and analysed with transverse microradiography (TMR). Anova and Pearson correlation coefficient were used for the statistical analysis. At the end of the 5-week in situ periods, fluorescence radiance had been regained to a level of 80-100% of the value before in vitro demineralisation, indicating remineralisation of the enamel samples. There were no differences in the fluorescence radiance gain between the 3 different F exposures. However, there was a statistically significant time trend (p < 0.001), and a highly significant linear dependence (p < 0.001) between the final measurements obtained with the laser fluorescence method (LAF) and the data obtained from TMR, r = 0.76. It was concluded that: (1) with the sensitive LAF method it was possible to register the small changes in the enamel week by week during in situ remineralisation: (2) when F dentrifice was used regularly, F supplements such as F lozenges or F chewing-gum did not significantly enhance the in situ remineralisation of incipient enamel lesions in healthy, young adults with normal salivary flow.

Adult↗
PubMed1997

Remineralization of root surfaces demineralized in solutions of differing fluoride levels.

The beneficial effects of fluoride on enamel have been well documented. However, limited data are available concerning the amount of fluoride required for beneficial effects on tooth root. Although studies have shown that fluoride inhibits root demineralization, the aim of this study was to investigate the location, extent and amount of remineralization on root dentin substrates after demineralization has occurred. The root surfaces of extracted human teeth were demineralized in a pure chemical buffer containing varying concentrations of sodium fluoride. After this lesion initiation, the same root sections were then placed into a remineralizing solution. The root sections were characterized after demineralization, and again after remineralization, by polarized light microscopy (PLM) and microradiography (MRG). Lesion depths after the demineralization phase were found to be inversely proportional to the fluoride concentration. When fluoride was present, bands or lines within the body of the lesion were observed with PLM and MRG. Using quantitative MRG, variations in mineral content and distribution were recorded. Examination of the root sections after the remineralization phase showed remineralization to have occurred on the remaining mineral and not on organic matrix devoid of mineral. The amount and location of mineral deposition may be of great significance in the arrestment and treatment of in vivo root surface caries.

Buffers↗
PubMed1991

Lipid and protein density in the rat retina: a microradiographical study.

Lipid and protein density in each retinal layer were determined microradiographically in retinal sections of 10 rats. Lipid in retinal sections was extracted with chloroform. The fraction of dry mass remaining after lipid extraction is mainly protein. The dry mass lost in chloroform processing was calculated to obtain the lipid density, which accounts for about 30% of the total dry mass density. The total dry mass density in each retinal layer is the sum of the lipid and protein density. Lipid should be regarded as an important X-ray absorber when determining the dry mass density in the rat retina with microradiography.

Animals↗
PubMed1969

Effect of sex hormones on bone in primary osteoporosis.

The effect of sex hormones on bone tissue was studied in 12 osteoporotic patients. Surfaces of bone undergoing formation and resorption were determined by quantitative microradiography of iliac crest biopsy samples before and after treatment with estrogens in 11 postmenopausal women and with testosterone in one gonadally competent man. Before treatment, bone resorption was greater than normal in all but one patient and bone formation was normal. After treatment, bone resorption decreased to within the normal range in all patients, and bone formation did not change significantly. Biochemical studies showed significant decreases in serum calcium, phosphorus, and alkaline phosphatase levels and in urinary excretion of calcium and hydroxyproline. These changes are believed to be the consequence of the effect of the hormones on bone. The data indicate that the major effect of sex hormones in osteoporosis is an inhibition of bone resorption.

Adult↗
PubMed1972

Short- and long-term effects of estrogen and synthetic anabolic hormone in postmenopausal osteoporosis.

In 29 women with postmenopausal osteoporosis, the proportion of total bone surface undergoing resorption or formation was evaluated by microradiography of iliac crest biopsy samples before and after short-term (2(1/2)-4 months) and long-term (26-42 months for estrogen and 9-15 months for anabolic hormone) treatment. After estrogen administration, values for bone-resorbing surfaces decreased, although less prominently after long-term than after short-term therapy. The magnitude of this decrease was positively correlated with the pretreatment value for bone-resorbing surfaces (P < 0.001). When the pretreatment value for bone-resorbing surfaces was used as a covariable, estrogen and anabolic hormone appeared to be equally effective. For bone-forming surfaces, short-term therapy with either hormone had no effect but long-term therapy significantly decreased the values. Serum immunoreactive parathyroid hormone (IPTH) increased significantly after estrogen therapy; the change in IPTH was inversely related to the change in serum calcium (P < 0.001, sign test). We conclude that the primary effect of sex hormones in postmenopausal osteoporosis is to decrease the increased level of bone resorption, perhaps by decreasing the responsiveness of bone to endogenous parathyroid hormone. However, this favorable effect, at least in part, is negated after long-term treatment by a secondary decrease in bone formation. Our data are consistent with the concept that the maximal benefit that can be derived from sex hormone therapy in postmenopausal osteoporosis is arrest or slowing of the progession of bone loss.

Aged↗
PubMed1991

Remodeling patterns in the bony otic capsule of the dog.

Quantum-type bone remodeling was studied in undecalcified temporal bones and long bone specimens from adult mongrel dogs by means of combined microradiography, osteofluorochrome labeling, and osteoid staining. The overall turnover rate of capsular bone was estimated to be low compared to that of extracapsular compact bone. Evolving secondary osteons were distributed centrifugally relative to the perilymphatic space. Moreover, a zone of bone tissue enclosing perilymphatic spaces was found completely devoid of evolving secondary osteons. Throughout the otic capsule, segmentary perivascular foci of resorption and formation were present. These findings indicate that remodeling of capsular bone is subject to sustained local inhibition. The significance of this conclusion is considered with special reference to otosclerosis.

Animals↗
PubMed2000

Remineralization effects of a two-solution fluoride mouthrinse: an in situ study.

Results from previous studies show that a two-solution fluoride (F) rinse is significantly more effective than a NaF rinse of the same F content of 250 microg/g (ppm) in remineralizing enamel and root lesions in an in vitro cyclic de- and remineralization model. In the present study, the two-solution rinse and two NaF rinses with F contents of 250 ppm and 1000 ppm were evaluated in an intra-oral remineralization model. Caries-like lesions were formed in the enamel of extracted human molars with the use of a pH 4 demineralizing solution. Thin sections of the enamel (approximately 120 microm) containing lesions were prepared, and the mineral contents of the lesions were assessed by quantitative microradiography. With the cut surfaces protected by nail varnish, 3 enamel specimens were mounted with wax in the lingual areas of a removable mandibular appliance. The study used a randomized, crossover design with seven subjects. In each of the 3 legs of the study, subjects wore the appliances continuously except when eating, drinking, and brushing their teeth. Twice daily (after breakfast and before bedtime), the subjects received a one-minute rinse with 20 mL of (1) 250-ppm-F NaF rinse, (2) 1000-ppm-F NaF rinse, or (3) 228-ppm-F two-solution F rinse. At the end of the 14-day experimental period, the sections were retrieved, and the mineral contents of the lesions were again assessed quantitatively. The results show that both the 1000-ppm-F NaF and 228-ppm-F two-solution rinses produced a greater (p < 0.05) remineralization than did the 250-ppm-F NaF rinse. The remineralization produced by the two-solution rinse was not statistically different (p > 0.05) from that produced by the NaF rinse with 4x the F content (1000 ppm F).

Analysis of Variance↗
PubMed1984

Factors involved in artificial caries induction by oral streptococci in extracted human teeth.

This study assesses the abilities of S. mutans GS5 and BHT and S. sanguis G9B to produce subsurface lesions on smooth surfaces of extracted human teeth and examines factors which might be responsible for any differences encountered. Teeth were incubated in Brain Heart Infusion broth containing 2% sucrose and a pure culture of the organism to be tested, the media being changed each day for eight days. Surface and media pH's were measured. The mineral content of both the surface enamel and the subsurface lesions was determined by contact microradiography. Significantly deeper and more demineralized lesions were produced by GS5 than by either BHT or G9B. GS5 also produced a lower surface and medium pH and a more dense coating on the teeth. Similar results were obtained with GS5 and G9B when the BHI broth was replaced with FMC synthetic media. It is concluded that the system described is suitable for studying cariogenic potential and will be useful in measuring the anticariogenicity of suspected therapeutic agents.

Culture Media↗
PubMed1984

Acceleration of remineralization in vitro by sodium monofluorophosphate and sodium fluoride.

Sixteen groups of artificial caries lesions were treated with from 75-900 ppm F from MFP, NaF, combinations of the two, or water for five min twice daily for ten days. Between treatments, the lesions were placed in a remineralizing solution at 37 degrees C. Quantitative microradiography of the treated lesions vs. matched untreated lesions showed significant remineralization of the surface layer and lesion body of all groups, including the water-treated control group. Fluoride treatments improved remineralization. Increasing the concentration of NaF had only a small effect on remineralization, but MFP was more effective at higher concentrations. Evaluation of MFP/NaF mixtures showed that greatest remineralization was obtained from a 75/225 ppm F ratio of NaF/MFP. This combination of F- and PO3F= was more effective than a fluoride concentration of 300 ppm F from either agent alone.

Dental Caries↗
PubMed1985

Histopathology of the initial lesion of the root surface: an in vitro study.

An acidified gel system was used to produce artificial caries lesions in root surfaces. Radiopaque surface layers were found with 47% of the lesions. Demineralized bodies of the lesion and mineralized zones of banding were seen in all lesions when examined by microradiography. Cementum and dentin seemed to respond to the acid attack in a similar manner. Although artificial root lesions did not simulate natural root caries entirely, the acidified gel system resulted in a reproducible method that might give insight into initial lesion formation on root surfaces. This technique may be used for studying the physico-chemical process involved in the demineralization of root surfaces and for testing the effects of various agents in the prevention of root caries.

Aged↗
PubMed1986

In vivo remineralization by a monofluorophosphate dentifrice as determined with a thin-section sandwich method.

Artificial caries lesions were formed in thin sections of subsurface enamel sandwiched between protective sheets of plastic. Six lesions were placed into the buccal surfaces of lower partial dentures of seven subjects, covered with a stainless steel mesh to provide a plaque cover, and brushed with either a sodium monofluorophosphate or placebo dentifrice for four weeks, by means of a double-blind random cross-over design. Analysis of the lesions by quantitative microradiography revealed that significant remineralization (21%) occurred in the monofluorophosphate group and significant further demineralization (27%) in the placebo group. The difference between the active and placebo treatments was significant (p = 0.02), showing that the monofluorophosphate was effective not only in preventing lesion progression but also in promoting mineral deposition. The simultaneous presence of remineralized lesions and lesions with increased demineralization showed the non-uniformity of conditions within a mouth.

Absorptiometry, Photon↗