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PubMedDate not supplied

Effect of fluoridated milk on progression of root surface lesions in vitro under pH cycling conditions.

The aim of this study was to assess the effect of milk with 0, 2.5 or 5 ppm F on progression and remineralization of caries-like root surface lesions using a pH cycling model. The root surface lesions were created utilizing a partially saturated lactic acid buffer at pH 4.6. Longitudinal sections were cut through the lesion and analyzed using polarized light microscopy (PLM) and microradiography (MRG). The sections were then coated with an acid resistant varnish, except the outer natural surface that would be exposed to water, milk or fluoridated milk and cycled in a de- and remineralizing system for 2 weeks. The lesions were characterized again by PLM and MRG after treatment. A significant reduction in lesion progression was found by PLM and MRG after treatment with either non-fluoridated or fluoridated milk when compared to the control group. Using quantitative MRG, mineral change and distribution in the lesions were recorded. A possible protective effect of fluoridated milk on root surface caries was supported by a reduction in the progression of the lesions and an increase in the mineral within the lesion.

Analysis of Variance↗
PubMedDate not supplied

Demineralization of dentin by Streptococcus mutans biofilms grown in the constant depth film fermentor.

To develop a bacterial demineralization model, we grew Streptococcus mutans biofilms in a constant depth film fermentor (CDFF) and studied the effects of sucrose pulsing frequency (SPF) in time on dentin demineralization. S. mutans biofilms were grown in dentin specimens with grooves and on dentin surface specimens for 20 days. During the experiments, 2% sucrose was pulsed either 4 or 8 times per day for periods of 30 min. Diluted brain-heart infusion medium containing 25 mM PIPES buffer and 1.5 mM CaCl2 was pulsed as the alternative growth medium. Specimens with intact biofilms were taken out on days 5, 12 and 20. The model was assessed by viable counts of the biofilm, mineral loss and lesion depth in the dentin specimens (by transversal microradiography) and pH measurements in the groove (by pH microelectrode). The results showed that biofilms formed on the dentin surface specimens were constant in viable counts for the low SPF, while this parameter tended to increase with time under the high SPF. Lesions with intact surfaces were formed and the lesion size increased significantly over time and increased significantly with increasing SPF. Typical Stephan curves were found after sucrose pulsing. The pH inside the groove returned to neutral under low SPF, but remained below 6.5 under high SPF. With the CDFF S. mutans biofilm model, lesions can be created in dentin within reasonable experimental time periods, as a result of the presence of a biofilm and in response to carbohydrate challenges.

Analysis of Variance↗
PubMed2004

Dental plaque as a biofilm: a pilot study of the effects of nutrients on plaque pH and dentin demineralization.

Direct or in situ methods (e.g., confocal microscopy, microsensors) are used to study non-oral biofilms for almost two decades, and they have recently been introduced in the research of dental plaque. We combined a pH microsensor technique and transversal microradiography (TMR) in a pilot study where the effects of nutrient availability on plaque acidogenicity and on the development of caries-like lesions were assessed. One volunteer accumulated dental plaque for 7 days in 0.2-mm-wide and 0.8-mm-deep dentin grooves at four conditions: (1) saliva only, (2) 8 x 5 min/day dipping in 10% sucrose solution, (3) 7 x 5 min/day consumption of sweet cookies plus one meal/day, and (4) subject's regular diet. Plaque pH versus time and depth profiles in the grooves were recorded ex vivo before and after sugar challenge. 'Saliva' plaque responded to sugar with slow pH decrease--minimum pH 5.6-5.8 was reached after 30 min, while sugar dipping resulted in metabolically active plaque (minimum pH 5.3-5.5 within 4-8 min). TMR analysis revealed no demineralization after these two periods. Metabolically active plaque leading to distinct lesions resulted from frequent plaque exposure to diets rich in starch and carbohydrates (groups 3 and 4). These findings strengthen the view that the plaque acidogenicity does not necessarily reflect cariogenicity, and that retention of food components may account for increased cariogenicity at plaque retention sites in the mouth.

Animals↗
PubMedDate not supplied

Effects of two fluoridation measures on erosion progression in human enamel and dentine in situ.

The aim of the present study was to evaluate the effects of fluoride on erosive mineral loss in human enamel and dentine using a cyclic de- and remineralisation model in situ. The study was a three-treatment (5 days each) crossover design involving 4 (enamel) or 6 (dentine) healthy volunteers. Samples were recessed in palatal mouth appliances and worn day and night except during meals and were demineralised extraorally with 0.05 M citric acid (pH 2.3) for 6 x 5 min daily. Fluoridation was performed with toothpaste (SnF2/Olaflur; 0.14% F-) for 3 x 5 min daily (toothpaste fluoridation) or with toothpaste in combination with a mouthrinse (SnF2/Olaflur; 0.025% F-) for 3 x 5 min daily and with a gel (NaF/Olaflur, 1.25% F-) on days 1 and 3 instead of the toothpaste (intensive fluoridation). In the control group no fluoridation was performed. Mineral loss (microm) was determined with the use of longitudinal microradiography. In enamel, mineral loss was 40.7 +/- 15.1 microm in the control group, 18.3 +/- 12.4 microm after toothpaste fluoridation and 5.0 +/- 12.2 microm after intensive fluoridation. The respective values for dentine were 49.0 +/- 15.4, 35.0 +/- 15.5 and 19.8 +/- 12.0 microm. All differences were statistically significant (p < or = 0.001). The results indicate that intensive fluoridation is effective in preventing enamel and dentine from mineral loss even under severely erosive conditions.

Amines↗
PubMedDate not supplied

Relationship between electrical resistance measurements and microradiographic variables during remineralization of softened enamel lesions.

The purpose of this study was to investigate the relationship between electrical resistance (ECM) measurements and microradiographic variables during remineralization of softened enamel lesions. Sound bovine enamel blocks were demineralized and, subsequently, were remineralized for 3, 4, 5, 7 or 14 days. All the specimens were assessed by ECM and transversal microradiography. The mean ECM values in each group increased after remineralization. The ECM values after remineralization (ECM1), mineral loss (DeltaZ) and maximum mineral content in the surface layer (V(max)) were significantly correlated with the remineralization time. The ECM1 values were also significantly correlated with DeltaZ and V(max). It is suggested that ECM could be used as a device to monitor mineral accumulation as a result of preventive treatment in vitro. However, it may take a much longer time to follow up the remineralization changes compared with demineralization.

Animals↗
PubMedDate not supplied

Efficacy of fluoride toothpaste in preventing demineralization of smooth dentin surfaces and narrow grooves in situ under frequent exposures to sucrose or bananas.

The use of models simulating fissures allows studying demineralization at sites that are most prone to caries in vivo. In practice, most in situ models use flat surfaces. Our objectives were: (1) to compare the demineralizing potential of sucrose solution with that of bananas and (2) to study the effect of fluoride toothpaste on demineralization in situ in an easily accessible site and a plaque stagnation site. Four volunteers wore bovine dentin specimens with narrow grooves and a smooth surface for two 1-week in situ periods, with eight 1-min sugar exposures daily: either by a rinse with 10% sucrose, or by consumption of a piece of banana. Twice daily, the appliance was dipped in toothpaste slurry of a control (fluoride-free) toothpaste at one side and a fluoride toothpaste at the contralateral side. Demineralization was assessed by transversal microradiography. We found no difference in dentin demineralization after frequent exposure to either sucrose solution or bananas. Fluoride toothpaste effectively protected dentin only at the smooth surface. In the grooves, fluoride affected the demineralization pattern; it drove lesions towards the bottom of the groove. We conclude that assessing only smooth surfaces in intraoral tests might lead to underestimated food cariogenicity and to overestimated efficacy of fluoride-containing toothpaste.

Adult↗
PubMedDate not supplied

Influence of the organic matrix on root dentine erosion by citric acid.

This investigation was conducted in an attempt to clarify the role of the organic matrix in bovine dentine demineralisation by 1% citric acid. Dentine slabs (n = 15) were treated for 2 min with 10% sodium hypochlorite (NaOCl, a strong protein solvent), 2% glutaraldehyde (GDA, a protein fixative) or deionised water (DIW, as negative control) prior to each of 5 demineralisation periods of 30 min. The mineral loss (DeltaZ), lesion depth (LD) and surface loss (SL) were determined after each period of demineralisation, by transverse microradiography. The NaOCl-treated group showed higher DeltaZ and LD than the GDA- and DIW-treated groups. No differences between GDA and DIW groups were found. The DeltaZ and LD profiles were explained by quadratic fits (r(2) >0.80; p = 0.001) in all groups. SL was detected only in the NaOCl-treated group. The data suggested that the maintenance of the organic matrix in the lesion might be important to reduce the erosion progression rate.

Animals↗
PubMed2006

Acid susceptibility at various depths of pH-cycled enamel and dentine specimens.

pH-cycling and in situ studies have shown that fluctuations in de-/remineralisation conditions or in fluoride usage can lead to laminations inside enamel or dentine lesions. Layers with different mineral content are thought to reflect the history of fluoride administrations. Studying the dissolution properties of such lesions at various depths -- using bulk specimens -- is presumably hampered by limited diffusion of acids through the lesion pores. Therefore, in this study the acid susceptibility of enamel and dentine lesions and the underlying sound tissues was studied by exposing sections to acid buffers from the cut rather than from the external surface. Specimens were obtained from a previous study of the effects of high-fluoride (0, 1,000, 2,000, 3,000/5,000 ppm F) toothpastes on enamel and dentine de-/remineralisation. Sections were subjected to acid buffers for 3 and 7 days and the changes in mineral content were monitored by contact microradiography. For enamel lesions a significant difference in dissolution over depth was observed between the groups subjected to the different fluoride schemes. At 7 days a dose response was found between the different fluoride groups and the lesion parameters. In the no-fluoride group dissolution in the original lesion and the sound tissue were similar. All dentine lesions which had been treated with fluoride showed inhibition of dissolution, but the inhibition did not increase with higher fluoride concentrations. Deeper into the dentine tissue there was some protection, but it was not statistically significant. We conclude that penetration of fluoride through the lesion pores determines the dissolution pattern of a lesion at various depths.

Acetic Acid↗
PubMed2006

Imaging artificial caries on the occlusal surfaces with polarization-sensitive optical coherence tomography.

Polarization-sensitive optical coherence tomography (PS-OCT) is a nondestructive imaging system that can utilize near-infrared (IR) light to produce depth-resolved images of dental enamel and has the potential to monitor early enamel occlusal caries. The objective of this study was to investigate the relationship between the magnitude of backscattered light and depolarization recorded by PS-OCT with changes in the enamel mineral volume in an artificial caries model. Artificial lesions were created on a selected region on the occlusal surfaces of sound posterior teeth (n=10) using a well-characterized 14-day pH cycling model. An all-fiber-based PS-OCT system operating at 1,310 nm was used to collect serial images at day 0 and day 14 prior to tooth sectioning. The quantitative mineral content profile and relative mineral loss, DeltaZ (%volxmicrom), of the carious enamel samples were obtained from transverse sections using high-resolution digital microradiography (DM). Line profiles of PS-OCT and DM images were used to evaluate the artificial caries severity and depth. The integrated reflectivity of the perpendicular-axis PS-OCT image, quantifying lesion severity, was correlated to the DeltaZ of the caries lesions. There was also a strong correlation between the lesion depth calculated from both imaging modalities. PS-OCT can image and quantify artificial occlusal caries by measuring the increase in backscattering and depolarization of near-IR light. This optical method has promising applications for in vivo detection and monitoring of early enamel occlusal caries.

Analysis of Variance↗
PubMed2006

Effect of calcium glycerophosphate on demineralization in an in vitro biofilm model.

The aim was to investigate the anti-caries properties of calcium glycerophosphate (CaGP) using an in vitro bacterial flow cell model. Four flow cells, inoculated from a chemostat containing a seven-organism bacterial consortium, were pulsed with sucrose twice daily, to provide an acidic challenge and pH-cycling conditions. Blocks of enamel and dentine were mounted in each flow cell. In a study on the effect of CaGP concentration, CaGP was pulsed into three of the flow cells, at the same time as the sucrose, to give concentrations of 0.10, 0.25 and 0.50%. Water was pulsed into the fourth flow cell with the sucrose. Microradiography revealed a significant dose response of decreasing demineralization as CaGP concentration increased. Reductions at 0.25 and 0.5% were significant when compared to the control. A second study investigated the effect of timing of CaGP pulsing, relative to sucrose, on enamel and dentine demineralization. CaGP (flow cell concentration 0.2%), was pulsed 1 h before, during or 1 h after the sucrose pulse; a water control was employed. In enamel, pulsing CaGP before the sucrose reduced demineralization significantly compared to concurrent pulsing, which in turn gave a significant reduction compared to pulsing after sucrose, which did not reduce demineralization significantly compared to the water control. In dentine, CaGP reduced demineralization significantly only when pulsed before the sucrose. The findings suggest that in vivo, the anti-caries potential of CaGP may be greater if it is applied before a cariogenic challenge.

Actinomyces↗
PubMed2006

Methods for assessment of dental erosion.

Various assessment techniques have been applied to evaluate the loss of dental hard tissue and the surface-softened zone in enamel induced by erosive challenges. In this chapter, the most frequently adopted techniques for analyzing the erosively altered dental hard tissues are reviewed, such as profilometry, microradiography, scanning electron microscopy, atom force microscopy, nano- and microhardness tests and iodide permeability test. Moreover, methods for chemical analysis of minerals dissolved from dental hard tissue are discussed. It becomes evident that the complex nature of erosive mineral loss and dissolution might not be comprehended by a single technique, but needs application of different approaches for full understanding.

Fluorescence↗
PubMed1994

Morphogenesis of the osteo-architecture in the carnassial region of the feline mandible, as demonstrated by microfocal radiography.

For the first time, osteogenesis was observed using direct magnifying microradiography, a noninvasive technique that has a high power of resolution. Thus, it was possible to correlate different stages of bone maturation in the feline mandible with specific functional demands. Our observations suggest a relationship between osseous structure and the mode of feeding and content of the diet.

Animals↗
PubMed1988

Influence of extraoral xylitol and sucrose dippings on enamel demineralization in vivo.

This paper describes the effect of xylitol on demineralized enamel in plaque-free and plaque-covered conditions in vivo. Fissure-like plaque retention grooves were created in 66 human enamel blocks and demineralized in vitro. The blocks were mounted in a prosthesis of 11 participants, who used a 2.5% xylitol, a 2.5% sucrose solution or water extraorally in a randomized cross-over design, for three periods of 16 days. The participants submerged the prosthesis twice a day in the solution during 5 min. Mineral loss and lesion depth were measured before and after the in vivo experiment, using quantitative microradiography and polarized light microscopy. Lesion depth at the surface enamel was +/- 45 microns, at the wall of the grooves +/- 30 microns and at the bottom of the grooves +/- 50 microns before the experiment. After 16 days the lesion depth at the wall of the grooves was +/- 40 microns and at the bottom of the grooves +/- 75 microns. In the grooves no differences were found between the xylitol, the sucrose and the water treatment. At the surface enamel a significant reduction of enamel demineralization was found after the xylitol dippings. The lesion depth at the surface enamel increased 17 microns after the sucrose treatment and 7 microns after the xylitol treatment. The mineral loss after the sucrose and the water treatment were both approximately three times higher than the mineral loss after the xylitol treatment.

Adult↗
PubMed1988

Optical quantitation of natural caries in smooth surfaces of extracted teeth.

An optical instrument is described which quantitates incipient smooth surface caries lesions in vivo. The possible role of such quantitation in caries management and in clinical caries research is discussed. The instrument uses a bundle of small fibres in an 'optical needle' with a flat end that is placed on the lesion. Half the fibres are used to illuminate the lesion and the other half to collect the light backscattered by the lesion interior. In this geometry, lesions reflect much more light than does sound enamel. The instrument has been validated against natural lesions in extracted teeth, and the depth of these lesions and their mineral loss were measured by microradiography. The correlation coefficient between these two parameters was 0.96 and the correlation between optical measurement and lesion depth 0.71.

Calibration↗
PubMed1988

In vivo progress of enamel and root surface lesions under plaque as a function of time.

This paper deals with enamel and root surface demineralization under plaque in vivo as a function of time. The enamel was demineralized using the Ogaard method in which preformed orthodontic bands are attached to the premolars in situ for 4, 6, and 8 weeks; a niche in the bands is responsible for plaque accumulation. In a second experiment cement-covered root surfaces (and enamel) were mounted on a removable appliance (Hawley retainer). Also in this case an orthodontic band was placed over the samples to create a space for plaque accumulation of about 0.8 mm between sample and band. All samples were analyzed by means of microradiography. The results show that (1) demineralization of enamel with the Ogaard method and using the Hawley retainer gives values for lesion depth and mineral loss that are statistically not significantly different; (2) lesion progress and mineral loss in vivo is about 2.5 times faster in roots than in enamel; (3) the demineralization in enamel is roughly linear with time, and (4) roots demineralize in vivo very fast during the 1st week and much more slowly there after.

Dental Caries↗
PubMed1988

Suitability of human, bovine, equine, and ovine tooth enamel for studies of artificial bacterial carious lesions.

The progress of artificial caries-like lesions created in human, bovine, equine, and ovine enamel has been studied. Lesions were produced by exposure to an acid gel system or by 5-day exposure to a sequential batch culture technique using Streptococcus mutans NCTC 10832. Longitudinal ground sections were prepared. The lesions were of similar appearance in all species when examined in polarized light. The depth in human enamel was approximately half that in the animal species. Microradiography confirmed subsurface demineralization in all four species. Similar depth ratios were seen in the scanning electron microscope, but there were structural differences between lesions in human and animal teeth. Lesions in bovine teeth were more like those in human, but lesions in equine and ovine teeth were markedly different. Substitution of these animal enamels for human enamel in caries experiments demands that these differences be taken into account. Scanning electron microscopy is capable of resolving features in artificial caries lesions which cannot be differentiated by polarized light techniques. The latter will demonstrate generalized mineral loss, but scanning electron microscopy is required to characterize the sites of mineral loss.

Adult↗
PubMed1989

In vivo study on the prevention of postradiation caries.

Postradiation caries is usually prevented by the application of topical fluorides (F) at high concentrations. The aim of this study was to develop an optimal preventive program for postradiation caries by evaluating the effects of F concentration and application procedures in subjects with radiation-related xerostomia. Six ground enamel slabs were mounted on each side of the lower denture of each of 7 xerostomia patients. Four procedures were used: no F exposure (control), neutral F gel applied every 2nd day or weekly, and a daily rinse with a F mouthwash for a period of 6 weeks. The enamel slabs were analyzed at weekly intervals by scanning optical monitoring, longitudinal microradiography, and scanning electron microscopy. In addition, hardness measurements were performed on the slabs. F analyses of the enamel slabs were done prior to their insertion in the appliances and after 6 weeks of intraoral exposure. In the control experiments severe demineralization of enamel occurred within 6 weeks. Application of F gel or the use of the F mouthrinse resulted in a significant inhibition of the demineralization process. Of the procedures evaluated, F gel applied every 2nd day was the most effective in preventing the onset of postradiation caries.

Aged↗
PubMed1989

Correlation between physical changes in tooth enamel and changes in iodide penetrability following in vitro or intraoral demineralization.

Demineralization of bovine tooth enamel was assessed by various physical means, and results were compared to measured changes in penetrability to iodide ions (delta Ip). Blocks of bovine enamel were exposed in vitro to lactate buffer (pH 4.3) containing 25 mM CaCl2 and 10 mM KH2PO4 for up to 4 days. Delta Ip increased over a wide range with time. A plot with respect to microhardness exhibited a pronounced inflection, with delta Ip rising rapidly at indentation depths greater than 2.5 microns. Microradiography and polarized light microscopy demonstrated subsurface lesions coincident only with the higher delta Ip values. The limited demineralization during the early time periods, therefore, was associated with only minimal changes at or near the enamel surface, yet could be detected readily with the delta Ip system. Demineralization produced intraorally in subjects rinsing with 5% sucrose was accompanied by increases in delta Ip, but no changes in surface microhardness or microscopic appearance of the enamel. It appeared that, under these conditions, demineralization was limited to the surface and corresponded to the very early phases of lesion formation.

Animals↗