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PubMed2005

Factors associated with active white enamel lesions.

OBJECTIVE: The aim of this study was to assess the factors associated with the presence of active white enamel lesions among public school students in the city of Natal, Brazil. METHODS: A convenience sample of 300 boys and girls aged between 7 and 12 years was selected among the pupils attending public schools in the city of Natal. Only those children presenting with opaque and rough-surface white lesions in a region of biofilm accumulation on the vestibular surface of permanent upper incisors were included. The investigation took the form of a cross-sectional study. A chart containing individual data was used, and a clinical examination was performed to determine the oral health status of the children, including caries (DMF-s(1), DMF-s(2), DMFdmf, dmf and total number of teeth with caries) and oral hygiene status (Gingival Bleeding Index and Visible Plaque Index). Data underwent descriptive analysis and analysis of variance, and chi-square tests were used for the comparison of continuous and dichotomous variables between groups with one, two, or three or more white lesions. RESULTS: On average, each child presented with 2.3 teeth affected by white lesions, relatively high indices of dental caries and poor oral hygiene, with an 85% rate of localized plaque on the surfaces of teeth with lesions. The presence of visible plaque was statistically significant between the three groups, based on the number of lesions (P = 0.006), indicating a positive association between the number of lesions and the presence of biofilm. CONCLUSION: There is a strong association between the presence of dental biofilm, high indices of caries and active white enamel lesions. Full professional effort is needed in order to motivate children to carry out oral hygiene sufficient for the adequate control of dental biofilm.

Analysis of Variance↗
PubMed1997

Effects of acidification on growth and glycolysis of Streptococcus sanguis and Streptococcus mutans.

After carbohydrate intake, pH in dental plaque decreases rapidly and reaches about 4 within a few minutes. The acidification not only promotes demineralization of tooth surface but can also cause damage to bacteria in dental plaque. We, therefore, investigated the effect of acidification on the dental plaque bacteria Streptococcus sanguis and Streptococcus mutans. At pH 4.0 and 4.2, both growth and glycolytic activities in these streptococci were repressed. Prolonged acidification (for 60 min at pH 4.0) not only repressed both growth and glycolytic activities but also impaired them in S. sanguis cells with concomitant inactivation of the glycolytic enzymes, hexokinase, phosphofructokinase, glyceraldehydephosphate dehydrogenase and enolase. The impaired abilities of glycolysis and growth recovered following incubation at pH 7.0 for 80-90 min, and this was accompanied by reactivation of the glycolytic enzymes. On the other hand, these impairments were not observed in S. mutans cells exposed to prolonged acidification. These results indicate that the low pH frequently occurring in dental plaque may transiently impair streptococcal glycolysis and growth and that S. mutans is more durable to the acidification than S. sanguis.

Culture Media, Conditioned↗
PubMed1997

Concepts of dental caries and their consequences for understanding the disease.

The way in which we conceptually consider dental caries determines our choice of preventive and treatment strategy. In this paper the definition of dental caries is discussed and the related problems concerning causality are addressed. Dental caries reflects symptoms of ongoing and past disease--not the disease itself. As such, it is important to record early stages of signs of the disease, i.e. non-cavitated stages of lesion development. The dynamic nature of the processes leading to net loss of mineral (hence a lesion) is emphasized, and appreciating that caries is ubiquitous in populations around the world and initiation and progression of lesions continues lifelong leads to the logical conclusion that we can control dental caries through a variety of measures--but not truly prevent the disease. We can prevent cavities by controlling the patho-physiological events which may result in a net loss of mineral. The relative role of dental plaque in caries control is discussed in relation to the role of the many determinants which influence the likelihood for lesion development. It is concluded that several paradigms about the nature of dental caries should be reconsidered to provide the most cost-effective dental services.

Cost-Benefit Analysis↗
PubMed1997

How useful are cross-sectional data from surveys of dental caries?

Surveys are projects involving systematic data collection without a specific hypothesis to be tested and hence without a specific research design. This paper reviews their uses, and some of the issues involved with measuring dental caries in surveys. The principal benefits of surveys are in (a) monitoring trends in oral disease when the surveys are repeated periodically: and (b) giving dental health a visibility it might otherwise not get among policy-makers. On the other hand, they are of limited use in determining treatment needs for a population, evaluating treatment outcomes, and evaluating prevention programs. Some major issues in caries surveys today include difficulties with the DMF index; the use of exclusively visual versus visual-tactile criteria; "hidden" caries; and the appropriate role for early, non-cavitated carious lesions. The DMF index suffers from its mixing of disease and treatment, and more research is needed to determine the most appropriate role for exclusively visual criteria in surveys. Trade-offs, such as weighing the benefits of exclusively visual criteria against the probable greater difficulty in finding "hidden" caries, have not been determined. Inclusion of non-cavitated lesions in a survey will increase its cost. Organizers should therefore be clear before the survey on how this additional information will be used to justify the additional expense.

Costs and Cost Analysis↗
PubMed1997

Proposed methods for improving the efficiency of the DMFS index in assessing initiation and progression of dental caries.

Recent changes in the epidemiology of dental caries and advances in the development of new diagnostic measurement techniques have stimulated interest in improved methods of assessing changes in dental caries status. Traditional methods for assessing change focus primarily on the development of new lesions at the cavitation level and incorporate incomplete information on the progression of existing cavitated lesions. A methodology to expand the clinical recording of dental caries in clinical studies to include 1) both non-cavitated and cavitated lesions and 2) the surface area affected for restorations is suggested. New indices are proposed to estimate changes in the number of new lesions, the progression of existing carious lesions, and the total change in caries status for a subject. It is anticipated that the new indices will produce more efficient methods of assessing change in caries status in longitudinal clinical studies. The degree of improvement can be estimated directly. Improvements in efficiency may reduce the duration or number of subjects required in caries clinical trials.

Adolescent↗
PubMed1996

Microradiography and confocal laser scanning microscopy applied to enamel lesions formed in vivo with and without fluoride varnish treatment.

The aim of the present investigation was to combine 2 techniques suitable for lesion characterization: quantitative microradiography (TMR) and confocal laser scanning microscopy (CLSM) on in vivo induced lesions with and without a fluoride varnish (Duraphat) treatment. Orthodontic bands were attached to premolars to be extracted for orthodontic reasons to induce enamel caries on the buccal surfaces. In the caries development part of the study, 1 tooth of each pair received at the start 1 topical application with the fluoride varnish Duraphat, the contralateral tooth serving as untreated control. All teeth were extracted after 4 weeks. In the caries progression part, the premolars were banded for 4 weeks without any treatment to induce caries, 1 premolar in each pair was then extracted and analyzed. The contralateral tooth received one Duraphat application and was extracted after another 2 weeks. In the caries development part of the study, TMR analysis showed that the Duraphat treatment on sound enamel reduced lesion depth by 48% compared to the untreated control. In the caries progression part, no significant difference was found between the untreated teeth extracted after 4 weeks and the fluoride treated lesions extracted after another 2 weeks. CLSM images agreed well with the TMR measurements. In the fluoride treated lesions, the CLSM images showed more light scattering indicating precipitation of material.

Adolescent↗
PubMed1997

Fluoride-induced precipitates on enamel surface and subsurface areas visualised by electron microscopy and confocal laser scanning microscopy.

The present study examined the enamel surface after in vitro topical treatments with a neutral 2% NaF solution. For minimising the risk of artefacts, samples were inspected without pre-treatment as fresh, naturally wet specimens by complementary techniques: variable pressure electron microscopy (VP-SEM) and confocal laser scanning microscopy (CLSM). VP-SEM provided information on the surface morphology, whereas CLSM allowed non-destructive visualisation of subsurface areas. Neutral NaF solutions induced globular precipitates on the enamel surfaces. If the globules formed may be described as "calcium fluoride like material", the additional information of this experiment is that, after interaction with neutral solutions, they also contain considerable amounts of NaF. When the NaF solutions were soaked on pellets and then were brought into contact with the enamel surfaces, NaF crystallites of cubic shape are formed. Confocal optical tomographies of subsurface enamel after treatments with neutral NaF solutions revealed partly coroded enamel structures, whereas VP-SEM showed intact surfaces. In between the coroded areas, a fine granulate precipitate could be observed. This is evidence that fluoride induces the formation of sub-surface precipitates only when applied during demineralisation. The precipitate could be readily removed by 24-h contact with a KOH solution.

Adolescent↗
PubMed2004

Mechanical properties across hypomineralized/hypoplastic enamel of first permanent molar teeth.

The aims of the present study were to investigate the mechanical properties of first permanent molars affected with enamel hypomineralization or hypoplasia, and to describe the appearance of these lesions under scanning electron microscopy. Eight first permanent molar test teeth and two unaffected premolars (controls) were enclosed in resin, then sectioned axially and polished. The hardness and modulus of elasticity was determined from a single array of indentations made parallel to the amelo-dentinal junction using an Ultra-Micro-Indentation system. The teeth were then examined using the scanning electron microscope. The mechanical properties of the test teeth in the unaffected cervical region (hardness and modulus range, 2.03-4.99 GPa and 50.39-96.87 GPa, respectively) were similar to those of the control enamel (hardness and modulus range, 2.71-4.15 GPa and 62.06-95.77 GPa, respectively). Between the unaffected cervical enamel and the hypomineralized region there was a transitional area of 500-600 microm where the mechanical properties in the experimental teeth decreased linearly. The mechanical properties of the hypomineralized region of each experimental tooth were significantly lower than those of the control or cervical regions (hardness and modulus range, 0.07-1.74 GPa and 3.26-40.96 GPa, respectively). The scanning electron microscopy views revealed disorganized enamel with poorly demarcated prism boundaries in the affected regions. In conclusion, the hardness and modulus of elasticity of hypomineralized enamel in first permanent molars is significantly less than in unaffected areas of the same tooth. The reason for this is unclear but may be related to the lack of organization of the enamel crystals.

Crystallography↗
PubMed2005

Detection of initial caries lesions on smooth surfaces by quantitative light-induced fluorescence and visual examination: an in vivo comparison.

The aim of this clinical study was to compare the outcome of quantitative laser/light-induced fluorescence (QLF) and visual inspection (VI) for the detection of initial caries lesions on all maxillary and mandibular smooth surfaces in caries-risk adolescents. The subjects were 34 students, mean age 15 yr. A total of 879 buccal and 882 lingual surfaces were air-dried and visually examined at a magnification of x3.5. Fluorescence images of each smooth surface were captured with QLF\clin equipment, and QLF software 2.00 was used to display, store, and analyse the images. Fluorescence loss (deltaF; %) and area of the lesion (A; mm2), and fluorescence loss integrated over the lesion area (deltaQ; deltaF x A; % x mm2), were determined. The presence or absence of initial caries lesions was scored using both VI and QLF. A total of 87.2% of all smooth surfaces were scored as sound or initially carious when assessed by VI + QLF in combination: 4.9% were detected by VI alone and 7.9% by QLF alone. The parameters DeltaF, A, and DeltaQ differed significantly between lesions registered with VI + QLF and QLF alone. It was concluded that (i) QLF seems to be a sensitive method that is suitable for the detection of visually undetected initial caries lesions; and (ii) that the clinical use of QLF is limited by several confounding factors in caries-risk adolescents.

Adolescent↗
PubMed2006

Photosensitization of in vitro biofilms by toluidine blue O combined with a light-emitting diode.

In natural ecosystems, micro-organisms grow preferentially attached to surfaces, forming matrix-enclosed biofilms. The aim of this study was to determine photodestruction levels in biofilms after subjecting them to photodynamic therapy. Biofilms of Streptococcus mutans, S. sobrinus, and S. sanguinis were grown on enamel slabs for 3, 5 or 7 d. Both the number of viable micro-organisms and the concentration of water-insoluble polysaccharides were analysed, and mineral loss (DeltaZ) analyses were performed on the enamel slabs. The antimicrobial potential of toluidine blue O (0.1 mg ml(-1)), associated with 85.7 J cm(-2) of a light-emission diode, was evaluated on the viability of 5-d biofilms. Both the number of micro-organisms and the concentration of water-insoluble polysaccharide increased with the age of the biofilms. A significant reduction ( approximately 95%) in viability was observed for S. mutans and S. sobrinus biofilms following photosensitization, with a > 99.9% reduction in the viability of S. sanguinis biofilms. In conclusion, a biofilm model was shown to be suitable for studying changes in bacterial numbers and enamel mineralization and for demonstrating the potential value of photosensitization in the control of in vitro biofilms.

Analysis of Variance↗
PubMed1996

Laboratory studies of sweets re-formulated to improve their dental properties.

OBJECTIVES: To evaluate the potential dental effects of ten new types of sugar-free sweets formulated with Lycasin or isomalt as bulk sweeteners instead of sugars. METHODS: Examination of the sweets for their acidity, fermentability by oral microorganisms, influence on the demineralisation of dental enamel, and their influence on human interdental plaque pH, compared with conventional sugar-containing sweets. FINDINGS: The importance of reducing the levels of flavouring acids in the sweets was demonstrated. It was not straightforward to evaluate chocolate products in this system, but the potential benefits of re-formulating fruit gums, lollipops, chew-bars, toffee and fudge with Lycasin or isomalt in place of sugars were shown by determining their reduced acidogenicity and fermentability compared with conventional confectionery. CONCLUSIONS: The extent of demineralisation of dental enamel was related to both the acidity and the fermentability of the sweets. Re-formulating sweets with reduced acidity levels and bulk sweeteners not fermentable by dental plaque microorganisms can provide a basis for improving their potential dental effects.

Analysis of Variance↗
PubMed1992

Assessment of the cariogenic potential of fruit fingers, muesli bars and jelly beans.

Intra-oral tests of a fruit bar, a muesli bar and jelly beans were performed to establish their cariogenic potential by means of enamel hardness changes. Little difference was found when the fruit finger and muesli bar were compared. Surprisingly, the jelly beans did not produce a greatly increased degree of softening when compared with the fruit fingers. Statistical significance was not reached in either of the experiments carried out.

Adult↗
PubMed1999

Morphology of initial lesions of enamel treated with different commercial dentifrices using a pH cycling model: scanning electron microscopy observations.

The aim of this study was to evaluate and compare the 'calcium fluoride-like reaction products' formed, both on the surface and in the subsurface caries-like lesions of enamel, from different commercial dentifrices manufactured locally from developed and developing countries. The experiment was conducted by using the in vitro single-section technique under the pH-cycling system used for 10 days. The tested dentifrices include; Maxam DFP Maxam Tartar Controls, First, Tianqui Medicated (China); Vicco Vajradenti (India); Colgate MFP2. Crest Tartar Control (USA); and a non-fluoride dentifrice, Jie Yin (China) used as control. The surface and subsurface of the lesions, before and after treatment, were examined using scanning electron microscopy. Varying degrees of fine globular patterns of calcium fluoride-like material were observed on the enamel surfaces of five out of eight groups and in the subsurface of four groups. Two treatment groups showed a 'similar appearance' compared with the control and untreated groups. This study suggests and supports that, when compared with 'multinational dentifrices', some Chinese and Indian dentifrices manufactured locally failed to induce the typical morphological appearance of globules as seen with fluoride dentifrices.

Calcium Fluoride↗
PubMed1998

Human enamel as a substrate for in vitro acid dissolution studies: influence of tooth surface and morphology.

The variation in susceptibility of enamel to acid dissolution has been quantitatively assessed in vitro by examination of different surfaces of both maxillary and mandibular teeth of different morphology obtained from a pool of sound human teeth. The lingual/palatal surfaces of all teeth showed greater susceptibility to acid dissolution than the corresponding labial/buccal surfaces. The palatal surface of the maxillary teeth appeared more susceptible to acid than the lingual surface of the corresponding teeth in the mandible. The palatal surfaces of the maxillary teeth showed least variation in acid susceptibility, whilst the lingual surfaces of mandibular teeth and buccal/labial surfaces of teeth from both jaws showed much more variation between teeth of different morphology. These differences in susceptibility to acid dissolution probably reflect both developmental differences and post-eruptive changes in enamel and may contribute to the clinical presentation of dental disease. Importantly, the data indicates that careful selection of teeth for in vitro study of enamel dissolution processes is essential to minimise inter-sample variation. For such purposes, the palatal surface of the maxillary teeth appears to be most suitable.

Adult↗
PubMed1998

Fluoride uptake to demineralised enamel: A comparison of sampling techniques.

Fluoride uptake is a recognised way of assessing the potential anticaries efficacy of fluoride (F) treatments. The aim of the present study was to compare an abrasion method of sampling treated enamel, based on that of Weatherell et al. [Caries Res 1985;19:97-102], with the acid-etch method of Raven et al. [Caries Res 1991;25:130-137]. Two adjacent demineralised areas were created on the polished surfaces of bovine incisors using an acid gel system. One artificial lesion from each tooth was subsequently treated for 6 h at 37 degrees C with one of two fluoridated dentifrice slurries (1 part: 3 parts water), whereas the other was treated similarly with a slurry of non-F control dentifrice. One set of treated lesions was then separated, the base of each enamel block polished until planoparallel with the demineralised surface and the lesions isolated by cutting away the adjacent sound enamel. Each block was mounted on the probe of a digital micrometer and the demineralised surface abraded with silicon carbide lapping film until sound material was reached. Abraded material was dissolved in perchloric acid and the buffered solution analysed for fluoride by ion-selective electrode. Each lesion of a second set of treated, demineralised enamel blocks was etched by 20microl acid and the resulting solutions analysed for F. Mean F uptakes [microg cm-2 (SD)] were: abrasion (n = 7/treatment); F dentifrice A = 1.39 (0.89) and B = 0.86 (0.45) relative to non-F controls = 0.11 (0.12), 0.14 (0.06), respectively; and acid-etch (n = 14/treatment); A = 1.27 (0. 49), B = 0.69 (0.23), controls = 0.12 (0.06), 0.12 (0.06), respectively. Significant differences (p<0.05) for both data sets were: A>B> control. The results show good agreement between the sampling methods and demonstrate the ability of the abrasion technique to distinguish between F treatments.

Acid Etching, Dental↗
PubMedDate not supplied

Reproducibility of quantitative measurement of white enamel demineralisation by image analysis.

The reproducibility of measuring artificial enamel white spot lesions from captured photographic images using computerised image analysis was assessed. Enamel lesions were induced on the buccal surface of 22 human teeth over periods of 3, 7 and 14 days. Standardised photographs were taken from above and below the occlusal plane. These were repeated after 2 weeks. The photographs were converted into TIFF images and mean grey scale levels of the areas of etched enamel were measured using computerised image analysis. Assessment of repeat readings of the same slide showed good reproducibility for photographs taken below the occlusal plane. The limits of agreement showed reasonable agreement between readings carried out on two slides of the same tooth. Capturing TIFF images via 35-mm film and measuring grey scale levels by computerised image analysis is a useful method of quantitative study of early enamel demineralisation. This may be developed for application in the clinical setting.

Adult↗
PubMedDate not supplied

Distribution of exogenous proteins in caries lesions in relation to the pattern of demineralisation.

While it is believed that proteins may protect enamel from demineralisation, recent work has indicated that such material may also hinder remineralisation. For example, albumin will inhibit apatite crystal growth in vitro and is present in carious enamel in vivo. However, it is not clear whether (1) the distribution of proteins within lesions is restricted to specific lesion zones or (2) the origin of such proteins is endogenous (i.e. as a remnant of the developmental process) or exogenous, originating in the saliva or gingival crevicular fluid. The present study used a combination of immunohistochemistry and microradiography to determine the distribution of two proteins, serum albumin and salivary amylase, within natural white-spot carious lesions in relation to specific levels of demineralisation. The results indicated that albumin is found primarily in a region of between 10 and 20% demineralisation (an area of transition between the 'dark' zone and lesion 'body'), with smaller quantities occurring in the region between 0 and 10% demineralisation and trace amounts in the zone indistinguishable from sound enamel by microradiography. A similar distribution was found for amylase in that the heaviest labelling was within the 10-20% demineralisation zone, although little if any was present in the 0-10% zone. The presence of these molecules in a region of the lesion where some potential for reprecipitation may exist will have important implications with respect to lesion progression.

Albumins↗