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PubMed1997

A computer-assisted videodensitometric method to visualize mineral distributions in in vitro and in vivo formed root caries lesions.

A computer-assisted videodensitometry (CAV) method is presented for the microradiographical mineral determination and mineral visualization of in vitro and in vivo formed dentin lesions. The method employs as essential steps (1) image digitizing by a CCD camera, (2) conversion of gray values to equivalent aluminium thicknesses and (3) conversion of aluminium thickness to vol% of mineral. Procedure and accuracy are described. The CAV method is illustrated for dentin lesions formed in vitro as well as for clinical root caries lesions. The CAV method is especially advantageous for clinical lesions because it can be employed for very complex mineral distributions and irregular lesion outlines. In given areas of interest, the mineral distribution (in vol%) can be plotted in 3D form in pseudo-colors. Conventional microradiographical profiles can be obtained directly from the CAV images. For in vitro lesions, the mineral distribution parameters, lesion depth, mineral loss, and mineral acquisition values can be generated from CAV images with a reproducibility of better than 7%. The CAV method is a valuable tool in quantitative mineral studies of clinical lesions in extracted teeth as well as in in situ lesion investigations.

Absorptiometry, Photon↗
PubMed1997

Review on fluoride, with special emphasis on calcium fluoride mechanisms in caries prevention.

Low concentrations of fluoride have a beneficial effect on enamel and dentin de- and remineralization. After fluoride treatments, such as topical applications, rinses or dentifrices, salivary fluoride concentrations decrease exponentially in a biphasic manner to very low concentrations within a few hours. For treatments to be effective over periods longer than the brushing and the following salivary clearance, fluoride needs to be deposited and slowly released. Calcium fluoride (or like) deposits act in such a way, owing to a surface covering of phosphate and/or proteins, which makes the CaF2 less soluble under in vivo conditions than in a pure form in inorganic solutions. Moreover, due to the phosphate groups on the surface of the calcium fluoride globules, fluoride is assumed to be released with decreasing pH when the phosphate groups are protonated in the dental plaque.

Calcium Fluoride↗
PubMed1997

Fluoride in plaque fluid and saliva after NaF or MFP rinses.

A micro-analytic method, capable of measuring the fluoride concentration in 5 nl of plaque fluid, was used to follow changes in fluoride concentration in saliva and plaque fluid at 6 single tooth-sites in 6 subjects for 180 min after a 0.048 M fluoride rinse as a NaF or MFP (sodium monofluorophosphate) solution. The maximum fluoride concentrations in saliva after NaF was 13x higher than with MFP. About 5% of the total amount of fluoride following the 20 ml NaF rinse was retained in the oral cavity. The corresponding figure followig MFP was <1%. The saliva/plaque fluid fluoride ratios for upper molars and lower incisors were significantly higher than for the upper incisors and lower molars. There was a tendency for a decline in the ratios with respect to time for all sites. To characterize the plaque fluid fluoride intra-oral single-site distribution and clearance, fluoride concentration versus time (AUC) was calculated from 10 to 60 min after a rinse. The NaF AUC followed the order: upper incisor, lower molar, upper molar and lower incisors reflecting a different exposure and clearance pattern due to the different access of the plaque to saliva. The MFP AUC values varied more, but were all significantly lower than the NaF AUC values. Analysis of plaque fluid fluoride curves at various sites revealed an exponential decline in most cases. With NaF, the baseline plaque fluid fluoride levels were not reached within 3 h. It is concluded that NaF solutions result in a significantly higher intra-oral fluoride exposure than MFP solutions. The fluoride distribution and clearance of fluoride from different sites in the oral cavity are linked to salivary access to these sites. These site-specific differences may have clinical consequences with regard to the dynamics of fluoride in the de- and remineralization processes.

Adult↗
PubMed1999

Effect of chelating agents on the molecular composition and extent of decalcification at cervical, middle and apical root dentin locations.

The aim of this study was to investigate the interaction of two chelating agents used in endodontic treatment with dentin from different root locations. Standardized cervical, middle and apical root dentin specimens were prepared and subjected to treatment with 15% neutral EDTA and RCPrep. Following rinsing with water, dentin surfaces were studied by reflected light optical microscopy and micro-MIR FTIR spectroscopy, while the wash-off extracts were analyzed by atomic absorption spectrometry (AAS) to determine the content of calcium and phosphorus. Neutral EDTA removed the smear layer and opened tubules while RCPrep did not. FTIR measurements showed higher decalcification of dentin surfaces after neutral EDTA treatment although its effect was reduced at apical regions. AAS measurements of calcium and phosphorus confirmed the higher dentin dissolution potential of EDTA at cervical and middle root dentin locations. The results of the present study implied different reaction modes for the two chelating agents tested which might affect the efficiency of the chemo-mechanical preparation when these agents are used.

Analysis of Variance↗
PubMed2004

Solubility properties of human tooth mineral and pathogenesis of dental caries.

Dental research over the last century has advanced our understanding of the etiology and pathogenesis of caries lesions. Increasing knowledge of the dynamic demineralization/remineralization processes has led to the current consensus that bacteria-mediated tooth destruction can be arrested or even to some degree reversed by adopting fluoride and other preventive measures without using restorative materials. Our experimental approach provided new insight into the stoichiometries and solubility properties of human enamel and dentin mineral. The determination of the solubility product constant on the basis of the stoichiometric model (Ca)5.x(Mg)q(Na)u(HPO4)v(CO3)w(PO4)3.y(OH,F)1.z, verifies the difference in their solubility properties, supporting the phase transformation between tooth mineral and calcium phosphates in a wide range of fluid compositions as found in the oral environment. Further refinement of the stoichiometry and solubility parameters is essential to assess quantitatively the driving force for de- and remineralization of enamel and dentin in the oral fluid environment. Prediction of the effects of a combination of inhibitors and accelerator(s) on remineralization kinetics is also required. In order to develop devices efficient for optimizing remineralization in the lesion body, it is a critical question how, and to what extent, fluoride can compensate for the activity of any inhibitors in the mineralizing media.

Dental Caries↗
PubMed1996

Atraumatic restorative treatment (ART): rationale, technique, and development.

Despite long-term efforts to use appropriate dental equipment for treating dental caries in economically less developed countries, the predominant treatment remains extraction. The reasons for this failure to save teeth are given in this paper. Supported by results of research undertaken in economically developed countries, a 15-step treatment module for dental caries is presented. This technique, which is called Atraumatic Restorative Treatment (ART), is based on removing decalcified tooth tissue using only hand instruments and restoring the cavity with an adhesive filling material. The technique does not require electricity. The advantages and limitations of the technique are discussed and its use in a school oral health program in Zimbabwe presented. We conclude that ART can make restorative oral care more available to a larger part of the world population than it is today.

Adhesives↗
PubMed2001

Studies on dental erosion: an in vitro model of root surface erosion.

Most research on dental erosion has focused on erosion in enamel. However, the increasing retention of teeth into old age has increased the potential for root surface erosion. The nature and kinetics of root surface erosion have not yet been adequately explored. The objective of this project was to develop an in vitro model of root surface erosion in order to investigate the polarised light microscopy of controlled erosion and the histology and rate of demineralisation of this process in root cementum/dentine. The results demonstrate a process quite different in outcome from that in enamel erosion. Erosion results in loss of volume of enamel. However, it leaves a root surface softened though with little volume loss so long as the demineralised collagen remains hydrated. The polarised light histology was similar to that seen in root surface caries. The rate of erosive demineralisation of tooth roots by selected acids was investigated, with differing rates of demineralisation similar to that seen in enamel erosion observed. The process of erosion showed evidence of significant diffusion control.

Acetic Acid↗
PubMed1998

Dental erosion.

Tooth enamel erosion occurs only in susceptible individuals regardless of food and beverage consumption patterns, that is, consumption of an acidic drink or food alone is highly unlikely to cause erosion. Susceptibility is highly variable from person to person and multifactorial in nature, as are the causes of erosion itself. Tooth enamel erosion is relatively rare and is easily misdiagnosed. A thorough differential diagnosis that eliminates the many other possible causes of enamel loss must be conducted. It is important to distinguish dental erosion from dental caries. Although the end result is similar, these two pathologies rarely occur simultaneously at the same site. In cases of true erosion, the tooth enamel is demineralised by direct contact with acids, while caries is a disease that occurs by the action of acids produced by plaque biofilm micro-organisms. It should also be stressed, clinically speaking, that erosion is primarily a surface phenomenon, while caries generally begins as a subsurface demineralisation of enamel structure that eventually leads to a pit in the tooth surface. As tooth enamel erosion is relatively rare, and the result of many factors, further research is needed to determine why susceptibility to erosion differs so widely from person to person.

Acids↗
PubMed2000

The effect of different commercial dentifrices on enamel lesion progression: an in vitro pH-cycling study.

AIMS/OBJECTIVES: To evaluate and compare the de/remineralization effects of dentifrices manufactured locally in some developing countries. DESIGN: Utilisation of the in vitro single-section and the pH-cycling model. SETTING: Laboratory. TEST MATERIALS: Dentifrices: Maxam DFP, Maxam Tartar Control, First, Tianqi Medicated from China; Vicco Vajradenti from India; Colgate MFP2, Crest Tartar Control from USA; and one non-fluoride dentifrice as control. METHODS: Sound molars were painted, leaving a 1 mm wide 'window' on the buccal and/or lingual surface and placed in a demineralisation solution for 96 h to produce artificial caries lesion approximately 80-100 mm deep. The teeth were then longitudinally sectioned (approximately 100 mm thick), and randomly divided into 8 groups (22 sections/group). The pH cycling model was utilised for 10 days. OUTCOME MEASURES: Polarised light microscopy and microradiography were used to evaluate the lesion progression before and after treatment. RESULTS: The control group showed an increase in lesion depth of 70 per cent and was statistically different from some test groups which ranged from -2 per cent to 68 per cent (P < 0.01, t-test). Statistically significant differences were also observed among some of the fluoride containing groups. CONCLUSIONS: This study suggests that, when compared to 'multinational dentifrices', Chinese and Indian dentifrices manufactured locally failed to show 'healing' efficacy even though they claimed to contain varying levels of fluoride.

China↗
PubMed2000

Demineralisation and remineralisation of dentine caries, and the role of glass-ionomer cements.

In accordance with the principles of modern operative dentistry, to conserve tooth structure and to use therapeutic restorative materials, an understanding of the carious process in dentine and the biological properties of glass-ionomer cements (GICs) are necessary. Delineation of the outer necrotic from the inner vital and remineralisable carious dentine allows for the preservation of tooth structure. This delineation is not possible when relying on visual and tactile perceptions, but requires the use of a caries detecting dye. GICs are ideal dentine substitutes because of their anticariogenic properties, stable long-term ionic bonding, and ability to assist the process of remineralization. The range of usage of these restorative materials continues to expand with the development of improved products.

Apatites↗
PubMed2004

Low-levels of fluoride in plaque and saliva and their effects on the demineralisation and remineralisation of enamel; role of fluoride toothpastes.

AIM: To summarise support for current consensus on the likely means by which fluoride toothpastes reduce caries and review some relevant studies of the effect of low levels of fluoride on the demineralisation and remineralisation of enamel. The major anti-caries effect of fluoride toothpastes is thought to result from small but protracted elevations in levels of fluoride in plaque and saliva. Fluoride incorporated into enamel systemically does not reduce enamel solubility sufficiently to exert an anti-caries effect. Fluoride has the potential to exert an anti-caries benefit largely through three mechanisms; inhibition of demineralisation, promotion of remineralisation and interference with bacterial growth and metabolism. However, the low levels of fluoride thought to influence caries are insufficient to have a significant effect via the latter mechanism. Thus reductions in caries resulting from the use of fluoride toothpastes can be linked to modification of the demineralisation/remineralisation balance by direct effects on dental mineral exerted topically by low levels of fluoride. Numerous in vitro studies have shown that low levels of fluoride, typical of those found after many hours in resting plaque and saliva, and resulting from the regular use of fluoride toothpastes, can have a profound effect on enamel demineralisation and remineralisation.

Cariostatic Agents↗
PubMed2005

In vitro efficacy of a whitening toothpaste containing calcium carbonate and perlite.

OBJECTIVES: The studies described in this paper aimed to assess the stain removal efficacy, fluoride efficacy and abrasivity to enamel and dentine of a new whitening toothpaste containing calcium carbonate and perlite, using appropriate in vitro models. METHODS: Stain removal efficacy was assessed using the pellicle cleaning ratio (PCR) method. Fluoride efficacy was assessed using remineralisation, demineralisation and fluoride-uptake methods. Abrasivity was assessed using an enamel and dentine wear method. RESULTS: The results showed that the new whitening toothpaste was able to remove extrinsic tooth stain more effectively than three commercially available toothpaste formulations. The fluoride efficacy was superior to a non-fluoridated control and was not significantly different to a clinically tested fluoride-containing toothpaste. The abrasivity data showed that the calcium carbonate/perlite toothpaste is no more abrasive to enamel or dentine than two other commercially available whitening toothpastes. CONCLUSIONS: The studies show that the new whitening toothpaste is effective in extrinsic stain removal, has an efficacious fluoride source and does not have an undue degree of abrasivity to enamel or dentine compared to other relevant commercially available products.

Aluminum Oxide↗
PubMed2005

Effects of sanguinaria in fluoride-containing dentifrices on the remineralisation of subsurface carious lesion in vitro.

OBJECTIVE: The purpose of this study was to investigate the potential cariostatic benefits of dentifrice containing both fluoride (F) and sanguinaria (SG) in a silica abrasive formula using the microbial de- and re-mineralisation cycle model. METHODS: Samples of bovine tooth enamel were embedded in resin, polished, exposed to a lactate carbopol buffer system for 44 hours, and divided into one control and five test groups of 12 specimens each by randomised blocks with VHN stratification. Surface microhardness was compared before and after the microbial cyclic sequences. RESULTS: VHNs for groups treated with dentifrices containing 1,000 ppm F from MFP with or without bamboo salt (BS) were significantly higher than the control. The groups treated with dentifrices containing F from NaF/silica with or without SG had significantly higher VHNs than that with F from MFP/DCPD. The VHNs treated with dentifrice containing both NaF-SG demonstrated the highest among test groups, indicating that there may be a synergistic effect in remineralising the incipient subsurface lesion. CONCLUSION: The dentifrice containing both NaF and SG showed a significantly greater effect (p < 0.05) on the remineralisation of the enamel lesion than the other test dentifrices.

Alkaloids↗
PubMed2005

The effects of child formula toothpastes on enamel caries using two in vitro pH-cycling models.

AIMS/OBJECTIVES: To compare, using two pH-cycling models, the de/remineralisation effects of children's toothpastes on primary teeth. DESIGN: In vitro single-section and pH-cycling models. METHODS: Primary teeth were placed in demineralising solution for 96 hours to produce artificial carious lesions 60-100 microm deep. They were cut into 100 microm thick sections and assigned to 6 groups. Sections in Groups A and D were exposed to a non-fluoridated toothpaste, those in Groups B and E to half-pea-sized (0.16g) and those in Groups C and F to pea-sized portions (0.32g) of a 500ppm F toothpaste. pH-cycling Model I (Groups A, B, C), without added fluoride, ran for 7 days, while Model II (Groups D, E, F), with 0.25ppm F, ran for 10 days. OUTCOME MEASUREMENTS: Lesions were evaluated using polarised light microscopy and microradiography. RESULTS: Lesions in Groups B and E progressed by 64% and 61%, respectively, while those in Groups C and F progressed by only 19% and 23% respectively. CONCLUSIONS: Both 10-day and 7-day pH-cycling models were suitable for studying carious lesion progression in primary teeth (the demineralising and remineralising solutions of the 10-day cycling model contained 0.25ppm F). A pea-sized portion (0.32g) of 500ppm F toothpaste slowed down the demineralisation progression better than a half-pea-sized portion.

Cariostatic Agents↗
PubMed2006

A proposal for a new classification of lesions of exposed tooth surfaces.

In the presence of improved methods of identification and treatment of lesions on the exposed surfaces of teeth, it should now be acknowledged that the GV Black "classification of carious cavities" is out of date. This paper describes a new system, proposed in 1997, discussed broadly throughout the profession, and eventually modified. The system has been adopted in several regions around the world as being a useful corollary to the current developing concept of minimal intervention dentistry. It is now desirable to adopt a new approach to the identification and recording of the lesions caused by both caries and non-carious tooth loss. A major advantage arising from its adoption would be that it would encourage the profession to minimise the amount of normal healthy tooth structure that is often sacrificed in pursuit of the cavity designs as suggested by Black. The authors are members of a Project Group of the FDI Science Committee, and this paper explains the concept and offers justification for the adoption of the system.

Dental Caries↗
PubMedDate not supplied

Visualization of biological texture using correlation coefficient images.

Subsurface structural features of biological tissue are visualized using polarized light images. The technique of Pearson correlation coefficient analysis is used to reduce blurring of these features by unpolarized backscattered light and to visualize the regions of high statistical similarities within the noisy tissue images. It is shown that under certain conditions, such correlation coefficient maps are determined by the textural character of tissues and not by the chosen region of interest, providing information on tissue structure. As an example, the subsurface texture of a demineralized tooth sample is enhanced from a noisy polarized light image.

Humans↗
PubMed2003

Effect of an orphan response regulator on Streptococcus mutans sucrose-dependent adherence and cariogenesis.

Streptococcus mutans is the principal acidogenic component of dental plaque that demineralizes tooth enamel, leading to dental decay. Cell-associated glucosyltransferases catalyze the sucrose-dependent synthesis of sticky glucan polymers that, together with glucan binding proteins, promote S. mutans adherence to teeth and cell aggregation. We generated an S. mutans Tn916 transposon mutant, GMS315, which is defective in sucrose-dependent adherence and significantly less cariogenic than the UA130 wild-type progenitor in germfree rats. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and N-terminal sequence analysis confirmed the absence of a 155-kDa glucosyltransferase S (Gtf-S) from GMS315 protein profiles. Mapping of the unique transposon insertion in GMS315 revealed disruption of a putative regulatory region located upstream of gcrR, a gene previously described by Sato et al. that shares significant amino acid identity with other bacterial response regulators (Y. Sato, Y. Yamamoto, and H. Kizaki, FEMS Microbiol. Lett. 186: 187-191, 2000). The gcrR regulator, which we call "tarC," does not align with any of the 13 proposed two-component signal transduction systems derived from in silico analysis of the S. mutans genome, but rather represents one of several orphan response regulators in the genome. The results of Northern hybridization and/or real-time reverse transcription-PCR experiments reveal increased expression of both Gtf-S and glucan binding protein C (GbpC) in a tarC knockout mutant (GMS900), thereby supporting the notion that TarC acts as a negative transcriptional regulator. In addition, we noted that GMS900 has altered biofilm architecture relative to the wild type and is hypocariogenic in germfree rats. Taken collectively, these findings support a role for signal transduction in S. mutans sucrose-dependent adherence and aggregation and implicate TarC as a potential target for controlling S. mutans-induced cariogenesis.

Amino Acid Sequence↗