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PubMed1998

Plaque minerals and dental caries.

Studies to date show that extracellular fluid obtained from resting plaque is highly supersaturated with respect to enamel mineral and that, after one sugar rinse, it rarely becomes unsaturated, even though the pH decreases markedly. This is partly because Ca2+ is released from plaque pools and minimises the change in saturation level, that is, acts as a "saturation buffer". Theoretical considerations, however, suggest that, with repeated pH cycling, calcium and possibly phosphate and fluoride pools in plaque will become depleted, at which time a state of marked undersaturation of plaque fluid will appear when the pH decreases on glycolysis. Such plaque fluid would have a high demineralisation potential. An artificial solid-phase supplement of the ion reservoirs in plaque would be expected to delay the time when plaque fluid becomes unsaturated during multiple pH cycling events, and would be expected to have marked anti-caries effects.

Buffers↗

PubMedDate not supplied

Early childhood caries and risk factors in rural Puerto Rican children.

A sample of 167 Puerto Rican children whose ages ranged from six months to forty-seven months (mean = 23 months) were studied. Children were examined for Early Childhood Caries with light and mirror and a structured interview was administered to parents and caretakers to identify risk factors. Results indicated that only 37.4 percent of the children were free of decalcification lesions or frank decay. While 53.9 percent of the children had lesions on maxillary incisors, 40.0 percent had molars affected by decalcification lesions and caries. Analysis of risk factors indicate that giving the baby a bottle when crying at night, number of adults and children in the family, use of fluoridated dentifrice, and age of the child were associated with the caries process in these children. Bottle and breast feeding, per se, were not risk factors. Disease patterns suggest other dietary risk factors, such as frequent snacking on food/drinks with sugar.

Adult↗

PubMed1998

Plaque, plaque model systems and pH.

Four interlocking lines of research carried out during the Directorship of Dr TW Cutress in the Dental Research Unit were: plaque urea metabolism, which led to the study of plaque pH responses and their control; development of plaque-like biofilm model systems; plaque mineralisation to calculus; and plaque demineralisation of tooth tissue in caries. New modes of regulation of oral bacterial urea metabolism and its role in the mouth were discovered, especially a role as a pH-rise factor and in mineralisation processes. The development of microcosm plaques, consortia of major plaque species, and of the multi-plaque artificial mouth with the ability to measure pH continuously, has substantiated the theory that plaque thickness and fluid flow are important in determining plaque pH. For the first time, formation of large pH gradients inside plaque have been demonstrated and plaque pH experimentally controlled. Plaque growth curves can be accurately measured and procedures established for measuring antiplaque and anticaries agents. These studies exemplify the value of the fundamental approach adopted by Dr Cutress--that integrated, basic, applied, and public-health lines of research reinforce each other.

Bacteria↗

PubMed1998

A method of making decalcifications in the porcelain build up.

This article describes a method for making white decalcifications or modeling characterizations that attempt to duplicate natural teeth. Common techniques often use white stain applied to the wet porcelain or painted on as surface stain. A simplified and reproducible technique is provided that allows this characterization to be completed as part of the porcelain build up. A mixture of three powders causes an improved appearance that can lighten the incisal and occlusal surfaces to help create greater contrast with the body porcelain for a more natural result.

Dental Porcelain↗

PubMed1998

Bond strength to dentin with artificial carious lesions: influence of caries detecting dye.

PURPOSE: To evaluate the influence of dyes for caries detection on tensile bond strength of adhesive materials to artificial carious dentin. MATERIALS AND METHODS: Buccal and lingual enamel of human molars were removed leaving intact dentin surfaces. The entire surface of each specimen was covered with nail varnish, keeping a window area of 4 x 4 mm. Artificial carious lesions were induced with acidified gel. Three dyes (0.5% basic fuchsin; Caries Finder and Cari-D-Tect) were used according to manufacturers' recommendations. Specimens were etched with 35% phosphoric acid for 20 s, washed and dried, leaving a wet dentin surface. The adhesive system (Prime & Bond 2.0) was applied in two layers and light-cured. Restorative materials (TPH Spectrum, Dyract, Advance) were bonded using a 3-mm diameter inverted-cone mold. Control groups were made without dye. Eight samples were tested for each group. After 24 hrs of storage in distilled water, the samples were debonded using a testing machine at 0.5 mm/min crosshead speed. RESULTS: ANOVA and Tukey-Kramer test showed that TPH Spectrum (0.73 MPa) and Dyract (0.74 MPa) had similar bond strengths, and both were higher than Advance (0.0 MPa), which was statistically different (P < 0.01). The use of the dyes did not cause any changes in tensile bond strength for any tested materials.

Analysis of Variance↗

PubMed2003

Influence of abrasion in clinical manifestation of human dental erosion.

The influence of abrasion from oral soft tissues on softened enamel lesion remineralization and erosion development was investigated. Using orange juice, softened enamel lesions were produced on 20 human premolars assigned randomly to 10 volunteers. Sections used as control and two test slabs were cut from each tooth. One of the two slabs from each tooth had an appliance built on it, which protected the lesion from abrasion. The two slabs (with/without appliance) were bonded to the palatal surfaces of upper right and left lateral incisor teeth of the participants who chewed sugar-free gum four times daily. After 28-day intra-oral exposure, mineral loss (Delta Z) and lesion depth (ld) in both control and test samples were quantified using transverse microradiography, and the data was analysed by paired t-test. Delta Z was significantly lower in lesions with appliance (protected), but higher in lesions without appliance (unprotected) when compared with control (unexposed). Similar pattern was observed with lesion depth. In unprotected slabs the lesions were abraded resulting in eroded enamel lesions. It was concluded that erosion observed clinically is the combined effect of demineralization of the tooth surface by an erosive agent and abrasion of the demineralized surface by surrounding oral soft tissues and through food mastication. Abrasion from oral soft tissues can contribute to site-specificity of dental erosion.

Adult↗

PubMed2006

Precision of Raman depolarization and optical attenuation measurements of sound tooth enamel.

The demineralization of enamel that is associated with early caries formation affects the optical properties of the enamel. Polarized Raman spectroscopy and optical coherence tomography have been used to detect these changes and potentially offer a means to detect and monitor early caries development. The total optical attenuation coefficient as measured by optical coherence tomography and the polarization anisotropy of the Raman peak arising from the symmetric nu(1) vibration of PO4(3-) at approximately 959 cm(-1) have been demonstrated as being sensitive markers of early caries. This ex vivo study on extracted human teeth demonstrates that these measurements can be made with reasonable precision with concomitantly good repeatability and reproducibility in sound enamel. Such reliability is crucial for these techniques to have a practical clinical value.

Bicuspid↗

PubMed1996

Calculation of intercrystalline solution composition during in vitro subsurface lesion formation in dental minerals.

Applications of a novel technique to calculate intercrystalline solution composition during enamel demineralization are presented. Bovine tooth enamel blocks and carbonated apatite (CAP) compressed disks were demineralized in an in vitro subsurface lesion system. The demineralization medium was a 0.1 M acetate buffer at pH 4.5, containing calcium, phosphate, and fluoride (0.5 ppm). Mineral samples were demineralized for various times, and fluoride profiles and mineral density profiles of these samples were determined by electron microprobe and X-ray microradiography, respectively. A model independent data analysis (MIDA) technique uses these data along with the differential equations for mass transfer and permits calculation of the local intercrystalline solution composition profiles inside the porous mineral matrix as functions of time and position. The invariance in diffusivity with time as calculated in the analysis was taken as an indicator of the physical reasonableness of the method. Current outcomes suggest that it is the sharp gradient of fluoride concentration in the intercrystalline solution which causes the formation of subsurface lesions. Since the driving force for mineral dissolution is a function of solution composition, a gradient of this driving force is consequently formed. Using a compressed disk of carbonated apatite powder as a model for block enamel excluded the possibility of the existence of a gradient of mineral composition which could also cause a gradient of the driving force for mineral dissolution. An FAP surface complex hypothesis is consistent with the current view that fluoride in the intercrystalline solution has a stronger inhibition effect on the dissolution of mineral than does fluoride in the mineral phase. With the help of the MIDA technique, calculated results indicate that the mechanism of the formation of subsurface lesions is dynamically controlled by the intercrystalline solution composition.

Animals↗

PubMedDate not supplied

Binding characteristics of Streptococcus mutans for calcium and casein phosphopeptide.

Casein phosphopeptides (CPP) stabilize amorphous calcium phosphate (ACP) and may be used to localize ACP in dental plaque, maintaining a state of supersaturation with respect to tooth enamel, reducing demineralization and enhancing remineralization [Reynolds, J Dent Res 1997;76:1587-1595]. The aim of this paper is to investigate these effects by measuring the affinity and capacity of Streptococcus mutans for CPP-ACP. Using the equilibrium dialysis system described by Rose and Hogg [Biochim Biophys Acta 1995;1245:94-98], assessment of calcium binding by a plaque streptococcus at a fixed CPP-ACP concentration gives a series of CPP-ACP-influenced dissociation constants for calcium. These data can then be used to derive a true dissociation constant for CPP-ACP itself. The results demonstrate that CPP-ACP binds with about twice the affinity of the bacterial cells for calcium up to a value of 0. 16 g/g wet weight cells. Application of CPP-ACP to plaque may cause a transient rise in plaque fluid free calcium which may assist remineralization. Subsequently, CPP-ACP will form a source of readily available calcium to inhibit demineralization. Hence, CPP-ACP binds well to plaque, providing a large calcium reservoir, which is likely to restrict mineral loss during a cariogenic episode and provide a potential source of calcium for subsequent remineralization. Overall, once in place, CPP-ACP will restrict the caries process.

Binding, Competitive↗

PubMed2002

Scanning electron microscope study of the effects of soft drinks on etched and sealed enamel.

The purpose of this study was to determine the effects of cola and other acidic drinks on etched tooth enamel in a simulated oral environment. The test beverages were cola, orange soda, lemon soda, and sparkling mineral water. Sixty extracted premolars were divided into an experimental group (n = 40) and a control group (n = 20). Half of the buccal surface of each tooth in the experimental group was coated with wax. The teeth were etched for 60 seconds with 37% phosphoric acid, and half of the teeth were also bonded. The experimental group was further divided into 4 subgroups of 5 teeth each, and each subgroup was exposed to 1 of the test beverages in a thermocycling apparatus. The apparatus was designed to keep the teeth in artificial saliva for 2 hours and in the soft drink at room temperature for 15 minutes. This procedure was performed 3 times a day for 5 days. The control group was also divided into 4 subgroups of 5 teeth each. Half of the buccal surface of each tooth in 2 subgroups was coated with wax, and the teeth in the other 2 were left uncoated. One waxed and 1 unwaxed subgroup were then etched, and the other waxed and unwaxed subgroups were etched and bonded. The waxed subgroups were stored in artificial saliva for 5 days, and the unwaxed subgroups were examined without further exposure to liquids. Surfaces exposed to acidic soft drinks were compared with control surfaces under a scanning electron microscope. Defect zone borders were observed between the exposed areas and the wax-coated areas of teeth in the experimental groups, especially the subgroups exposed to cola, orange soda, and lime soda. Fewer defect zones were observed on teeth exposed to sparkling mineral water. The results indicate that acidic soft drinks cause enamel demineralization on etched tooth surfaces.

Acid Etching, Dental↗

PubMed1998

Phosphoprotein analysis of sequential extracts of human dentin and the determination of the subsequent remineralization potential of these dentin matrices.

Phosphoprotein appears to play an important role in the mineralization of dentin during tooth development and remineralization after demineralization by dental caries. To better understand this role, we describe the extraction and characterization of phosphoprotein from immature, human root apex dentin during and after EDTA demineralization. The extraction procedure included dissociation of the demineralized dentin matrix by guanidine hydrochloride (Gdn.HCl) followed by subsequent digestion with cyanogen bromide (CNBr) and collagenase. Characterization of these extracts included 'Stains-All' staining of SDS polyacrylamide gels (SDS-PAGE) and amino acid, protein and phosphorus analyses. The ability of these matrices to remineralize was determined by TEM and measuring calcium levels in the remineralized tissue by atomic absorption spectroscopy. The staining of SDS-PAGE gels and amino acid analysis showed that an intact phosphophoryn was extracted from the dentin of the immature apices during EDTA demineralization and that it had an apparent Mr approximately 140,000. In the subsequent extracts and digests, the phosphoprotein has a range of molecular weights, some of which may have been degraded products of the intact phosphoprotein. A greater quantity of phosphoprotein was found in the EDTA-demineralized dentin matrices than in dentin after Gdn.HCl, CNBr and collagenase digests. These EDTA-demineralized matrices also remineralized to a greater extent than those dissociated with Gdn.HCl. The differences in both the quantity and the quality, as defined by the amino acid residue profile, of the phosphoprotein in the sequential extracts of the root apex dentin may be important in affecting the ability of this tissue to remineralize.

Adolescent↗

PubMed1999

Real-time measurement of in vitro enamel demineralization in the vicinity of the restoration-tooth interface.

An X-ray attenuation method using photon counting (scanning microradiography) is presented for the real-time study of in vitro demineralization of dental tissues in the vicinity of the restoration-tooth interface. By repeated measurement of mineral content profiles during the course of demineralization, the pattern of lesion development and the rate of mineral loss can be studied. The method is illustrated by comparison of enamel demineralization near a polyacid-modified composite resin restoration, near a bis-GMA/TEGMA composite resin restoration, and in an unrestored control. The method has potential for study of the influence of restorative materials on susceptibility of tooth tissue to demineralization.

Journal Article↗

PubMed1999

In vivo caries-like lesion prevention with argon laser: pilot study.

OBJECTIVE: This clinical pilot study was conducted to investigate the effectiveness of argon laser irradiation to reduce demineralization or loss of tooth structure in vivo. SUMMARY BACKGROUND DATA: In vitro research previously demonstrated the ability of argon laser irradiation to reduce demineralization or loss of tooth structure. METHODS: Using the Ogaard model of producing demineralization, the experimental teeth were irradiated with argon laser of 250 mW (producing approximately 12 J/cm2) prior to banding. Polarized light evaluation of the sectioned, extracted teeth was used to determine the amount of demineralization. RESULTS: Results showed a 29.1% reduction in demineralization in the experimental teeth as compared to the bilateral control teeth. CONCLUSION: Low-power argon laser irradiation significantly reduced demineralization clinically.

Bicuspid↗

PubMed2000

Minimal intervention: a new concept for operative dentistry.

The term minimal intervention is relatively new in dentistry and has been introduced to suggest to the profession that it is time for change in the principles of operative dentistry. The disease should be treated first; the surgical approach should be undertaken only as a last resort and then with the removal of as little natural tooth structure as possible. This article discusses the advances in techniques and materials that have led to change and attempts to put them into perspective. Treatment should begin with identification and elimination of the disease. There will then be a need for limited restoration of actual cavitation arising from demineralization of the tooth crown. Restorations, per se, will not prevent or eliminate disease. Caries is a bacterial infection and, until the microflora is controlled, all restorations are at risk of further demineralization in remaining tooth structure. This leads to the continuum of replacement dentistry that keeps the profession occupied for much of its productive time. If this cycle is to be broken, the profession must first acknowledge the primacy of prevention.

Bacterial Infections↗

PubMed1982

Effect of initial demineralization on the permeability of human tooth enamel to iodide.

Blocks of intact human enamel were exposed for four successive periods of 5 min to 2 ml of 10(-2) M K-acetate at pH 4.0, 4.5 and 5.0. The permeability to iodide (Ip) and the amount of Ca dissolved were determined after each exposure. The Ip values varied considerably, but for each block there was a consistent increase in Ip with increase in acid exposures, and the Ca-Ip relationship was linear at all pH levels. The slope and intercept of the regression lines varied widely, but the correlation coefficients showed close fit of the data. The mean Ip values after the same period of exposure at pH 4.0 and 4.5 were statistically different from those obtained at pH 5.0, but the differences between the pH 4.0 and 4.5 values were not. This discrepancy is attributed to dissolution of surface enamel by the pH 4.0 buffer. Because loss of surface enamel is minimized by partial saturation of the buffer with Ca and phosphate, and oral fluids contain high concentrations of these ionic species, the iodide method should give valid measurements of the demineralization produced intarorally by acid and cariogenic foods.

Acetates↗

PubMedDate not supplied

Early detection of secondary caries using quantitative, light-induced fluorescence.

The authors hypothesize that the arrestment and remineralization of these lesions could be improved if secondary caries could be detected and monitored at earlier stages. Traditional diagnostic techniques detect secondary caries when it is relatively advanced and when significant tissue has been lost. This in vitro study evaluated the Quantitative Light-induced Fluorescence (QLF) system for detecting and monitoring demineralization surrounding tooth-colored restorations. This investigation was divided into three studies. The first study evaluated QLF for the detection and measurement of chemically induced lesions surrounding resin composite restorations. The second study evaluated QLF for the detection of demineralization around different tooth-colored restorations (glass ionomer, resin composite, compomer and smart material) created in a microbial caries model. Finally, the third study tested whether QLF was effective at detecting early wall lesions adjacent to resin composite restorations. Data from Study 1 demonstrated the potential for QLF to detect very early secondary caries and to distinguish between the different stages of early demineralization. Study 2 confirmed the potential for QLF to detect early secondary caries created by cariogenic bacteria and concluded that the four types of materials differed in their ability to prevent secondary caries in this model, with the glass ionomer being the most effective and the non-fluoride releasing composite performing the worst, which allowed for the development of larger lesions. The results of Study 3 suggest a potential application of the QLF system to detect early wall lesions. Data from this investigation strongly suggest that QLF is a potentially viable technology to detect and monitor early secondary caries.

Analysis of Variance↗

PubMed2004

Bioactive properties of milk proteins with particular focus on anticariogenesis.

Beyond nutrition, there is an increasing amount of data and information to demonstrate a bioactive role for dairy components in adults including a role in prevention of dental caries. Specifically, the casein fraction and hydrolysates thereof have been the focus of researchers investigating cariogenicity prevention. Tooth enamel is a polymeric substance consisting of crystalline calcium phosphate embedded in a protein matrix. Dental caries develop by acidic demineralization (calcium and phosphorus solubilization) of tooth enamel. Demineralization occurs directly (acidic food consumption) or indirectly (by fermentation products of dental plaque odontopathogenic bacteria growing on residual food particles between teeth or adhering to the plaque). Research efforts with milk derived bioactive peptides have focused on inhibition of cariogenic, plaque-forming bacteria, inhibition of tooth enamel demineralization, and subsequent enamel remineralization. Caseinophosphopeptides (CPP) and glycomacropeptide (GMP) have been patented for use in common personal hygiene products to prevent dental caries. Research has shown CPP and GMP to be growth inhibitory to the cariogenic bacteria Streptococcus mutans and other species. Additionally, CPP forms nanoclusters with amorphous calcium phosphate (AMP) at the tooth surface to provide a reservoir of calcium and phosphate ions to maintain a state of super saturation with respect to tooth enamel. This would buffer plaque pH, and also provide ions for tooth enamel remineralization. Glycosidic structures attached to GMP are important to numerous bioactive properties of the peptide including anticariogenicity. Like CPP, GMP has shown inhibitory activity to enamel demineralization and promotes tooth enamel remineralization.

Amino Acid Sequence↗

PubMed2002

Effect of a hydrophobic tooth coating on gingival health, mutans streptococci, and enamel demineralization in adolescents with fixed orthodontic appliances.

The effect of an anti-adhesive enamel coating on plaque accumulation, gingival health, and enamel demineralization was evaluated in 39 adolescents undergoing treatment with fixed orthodontic appliances using a prospective split-mouth design. Immediately after bracket insertion, the polymer was randomly applied after enamel etching to the buccal surfaces of the teeth in the left or right upper quadrant, leaving the opposite quadrant as an untreated control (218 test and 216 control teeth). Reapplications were carried out every 3rd month during the course or the study. The following data were collected at baseline and at designated follow-ups: visible plaque index, total viable counts and proportion of mutans streptococci in plaque samples, gingival bleeding index, and amount of gingival crevicular fluid. The incidence of enamel demineralization adjacent to the appliances was scored clinically at the termination of the orthodontic treatment. The observation time ranged from 6-24 months, during which the participants used fluoride rinses and toothpaste daily. A slightly impaired gingival health and increased levels or mutans streptococci compared with baseline was disclosed during the treatment. Five subjects showed enamel demineralization on a total of 30 teeth at the time of de-bonding. The results indicated no statistically significant differences between the enamel-coated and untreated teeth with regard to the studied variables at any follow-up. In conclusion, the present findings did not support a clinically beneficial effect of the polymeric tooth coating in a low-caries group of adolescents treated with fixed orthodontic appliances.

Acrylates↗