Evaluation Methods

This document is a summary of published work carried out by Unilever Dental scientists from January 1980 to December 2000. It includes published conference abstracts and papers from studies undertaken at Unilever laboratories as well as studies conducted with other groups involving Unilever scientists as co-authors.

Unilever Dental Research gratefully acknowledges the contribution of its many academic colleagues.

Increasing the sensitivity of caries clinical trials by applying logistic modelling to specific teeth

Huntington E Comm Dent Oral Epidemiol 1985, 13, 264-267

An alternative statistical approach is proposed for analysing data from longitudinal clinical trials. Caries increments on those teeth which are known to be particularly susceptible to caries for the population under study are represented by a linear logistic probability model. Expression of the caries increments in the form of a probability model should lead to a better understanding of the relative importance of the various factors which contribute to the caries increment in the population under study. When this model was applied to caries increments on the permanent second molars of children aged 11-13 years at the baseline of two three-year trials, the sensitivity of statistical analysis was up to five times greater than that obtained with traditional statistical methods.

Comparison of fibre optic transillumination with clinical and radiographic caries diagnosis

*Stephen KW, *Russell Jl, *Creanor SL and Burchell CK (*University of Glasgow Dental School, Glasgow, UK) Community Dent Oral Epidemiol 1987, 15, 90-94

Fibre optic transillumination (FOTI) has been employed during the course of a three-year clinical dentifrice trial which initially involved 3,003 children. At the initial examination, a subgroup of 813 13-year-olds, and at the following annual visit, 2,247 14-year-olds, were examined using a 150W lamp and 0.5mm diameter probe. Routine clinical and radiographic examinations were performed separately. Compared to the clinical scores for anterior teeth, FOTI detected an additional 64% of interproximal lesions at the first visit while, for the larger number of children at the second visit, the increase in lesion detection level using FOTI was 37%. For the posterior teeth the comparable figure at the second examination was 92%. When FOTI data were compared to radiographic data for more than 52,000 posterior interproximal surfaces FOTI could only detect 17%of radiographic Grade 2 lesions and 48% Grade 3 lesions. Thus any assumption that FOTI diagnoses may be a substitute for bitewing radiography appears premature.

Early microbial colonisation of enamel – an in situ model MacPherson LMD*, MacFarlane TW*, Stephen KW* and Burchell CKb
(*Department of Oral Medicine and Pathology, University of Glasgow Dental Hospital and School, Glasgow, UK) J Dent Res 1988, 67, 670

An in-vitro demineralisation screening model. Development and fluoride dose response
Page DJ J Dent Res 1989, 68, 587

Evaluation of microradiographs by computerized image analysis
Schäfer F, Joyner DJ and Burchell CK Caries Res 1989, 23, 116

Longitudinal analyses of FOTI and x-ray caries diagnostic anomalies
Stephen KW* Miller S*, Strang DM*, and Burchell CK (*University of Glasgow Dental School, Glasgow, UK) Caries Res 1989, 23, 108

Use of baseline caries criteria to select panellists to increase clinical trial sensitivity
Burchell CK, Stephen KW*, and Huntington E (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1989, 23, 103

Alternative equivalence studies for test and control fluoride toothpastes
Gilbert RJ, Duckworth RM, Schafer F and Raven SJ
J Dent Res 1990, 69, 221

Reproducibility of caries diagnosis using FOTI with different light intensities
Chesters RK, Russell J , Matthias AJ and Huntington E
J Dent Res 1991, 70, 364

IMAGEM 1

Comparison between evaluation methods for the anti-caries efficiency of monofluorophosphate containing dentifrices
Raven SJ, Schäfer F, Duckworth RM, Gilbert RJ and Parr TA
Caries Res 1991, 25,130-137

A comparison is described of three methods of preclinical assessment of potential anti-caries efficacy for topical fluoride treatments. Methods are compared using dentifrices containing 1000, 1500 and 2500 ppm F as sodium monofluorophosphate (SMFP). These formulations have been shown elsewhere to give statistically significant dose response of increasing anti-caries efficacy [Stephen et al., 1988]. An in situ enamel insert model, oral fluoride pharmacokinetics and F uptake to demineralised enamel are all shown to correlate with clinical efficacy for the test dentifrices studied.

Improved sensitivity in caries clinical trials by selection on the basis of baseline caries experience
Burchell CK, Stephen KW*, Schäfer F and Huntington E (*University of Glasgow Dental School, Glasgow, UK)
Community Dental Oral Epidemiol 1991, 19, 20-22

As caries prevalence in some countries declines, and panel sizes for discriminating anti-caries clinical trials inevitably increase, the need for participant pre-selection grows to avoid escalating cost and manpower problems. Hence, retrospective analyses of data were undertaken, from a three-year double-blind caries clinical trial where a linear fluoride doseresponse had been obtained. As a result, it was demonstrated that the eruption status of permanent second molars, in 3005 participants aged 11-12 year at outset, when coupled with their baseline clinical DMFT values, provided a sound basis for panellist size prediction without loss of sensitivity. Thus, had only those subjects with DMFT >4, with at least three of their permanent second molars, erupted been selected following clinical baseline examination, the same sensitivity would have been achieved with 52% fewer subjects Furthermore, using these criteria, selection can be made on site, in real time, and a child informed whether its immediate participation in a trial is possible.

The effect of lesion characteristics on remineralization and model sensitivity
Schäfer F, Raven SJ and Parr T
J Dent Res 1992, 71, 811-813

A major criterion for assessing the value of any experimental model in scientific research is the degree of correspondence between its results and data from the real-life process it is designed to model. Intra-oral models aimed at predicting the anti-caries efficacy of toothpastes or other topical treatments should therefore be calibrated against treatments proven to be effective in a caries clinical trial. For this to be achieved, it is necessary that a model with high sensitivity be designed, while at the same time retaining relevance to the process to be modeled. This means that the effects of the various experimental conditions and parameters of the model on its performance must be understood. The purpose of this paper was to assess the influence of two specific factors on the performance of an in situ enamel remineralization model, which is based on human enamel slabs attached to partial dentures. The two factors are initial lesion severity and origin of enamel sample. The results indicated that initial lesion size affected whether net remineralization or net demineralization occurred during in situ treatment. Samples with an initial range from 1500 to 2500 (Z) tended more toward demineralization than did samples with Z>3500. This means that treatment groups must be wellbalanced with respect to initial lesion size. Differences in initial demineralization severity between different tooth locations must also be considered so that systematic treatment bias can be avoided. The solution used in the model discussed here is based on a balanced experimental design, which allows this effect to be taken into account in the data analysis.

Intraoral models to assess cariogenicity: evaluation of oral fluoride and pH
Duckworth RM and Gilbert RJ
J Dent Res 1992, 71, 934-944

The main purpose of this paper is to review the various methods used for evaluation of fluoride retention in saliva, plaque, and enamel following application of topical anti-caries treatments such as F dentifrices and F mouthwashes. Such methods monitor delivery of fluoride to the site of action, the mouth, and so can be regarded as assessing potential for treatment action. It is concluded that intraoral fluoride measurements are appropriate to support bioequivalence claims for anticaries treatments, provided that particular chosen methods have been calibrated against clinical data. Studies purporting to show superiority are of interest mechanistically, but links to caries are not sufficiently understood to define superiority claims. A wide variety of methods has been used for determination of the fluoride content of enamel. Of these, well established methods such as the micro-drill and acid-etch procedures are appropriate for routine comparative testing, whereas sophisticated instrumental techniques such as SIMS are more appropriate for detailed mechanistic studies. Intra-oral pH measurements are also relevant to many topical treatments. Single-site determinations in plaque are preferred, but for comparative studies non-specific determinations may be adequate.

Comparison of oral habits collection methods
Schäfer F, Jacobson APM*, Chestnutt IG*, Moralee DS and Chesters RK
(*University of Glasgow Dental School, Glasgow, UK)
J Dent Res 1992, 71, 747

Intra-oral remineralisation models as alternatives to rat caries experiments
Roberts AJ, Vernon PG, Huntington E, Best JS* and D’Agostino RB* (*Department of Pharmacology, University of Rochester, NY, USA)
J Dent Res 1992, 71, 672

IMAGEM 2

An orthodontic banding model for assessing early enamel caries<br> Melrose CA*, Lovius BBJ* and Schäfer F (*University of Liverpool Dental School, Liverpool, UK)
J Dent Res 1993, 72 732

Touch electrodes versus plaque sampling methods in plaque pH determination
Preston AJ*, Edgar WM* and Gibbs C
(*University of Liverpool Dental School, Liverpool, UK) J Dent Res 1994, 73, 339

Diagnosis of approximal caries in a caries clinical trial: Comparison of FOTI and radiography
Schäfer F, Kavanagh D*, Ellwood RP*, O’Mullane DM* and Chesters RK
(*University College of Cork, Ireland)
Caries Res 1994, 28, 209

Comparison of two cariesdiagnostic approaches
Hargreaves JA*, Baylor N and Chesters RK
(*Faculty of Dentistry, University of Alberta, Edmonton, Alberta, Canada)
Caries Res 1994, 28, 189

Validation of the intraoral delta Ip system and use of the system to test the efficacy of Mentadent® toothpaste
Kashket* S, Mengshoell K*, Cancro L, Stepanians MN*, D’Agostino R* (*Forsyth Dental Centre, Boston University, USA)
J Clin Dent 1994, 5, 110-113

Ongoing efforts within the oral care industry to improve dentifrices by the addition of anti-tartar compounds bicarbonate and other agents, have necessitated the continuing evaluation of new products in order to assure their anti- caries effectiveness. However, clinical evaluation of new products is time consuming, prohibitively expensive and ethically questionable. Recently, a number of intra-oral models have been developed that appear to be well suited to evaluate new products. In the present study, an intra-oral system was used that monitors short term demineralization of surface enamel. Subjects wore appliances that contained Streptococcus mutans-coated blocks of bovine enamel and rinsed first with 15ml of a 20% slurry of dentifrice and, after 30 minutes, with a 10% sucrose solution. Iodide penetrability (Ip) was determined before and after each intra-oral exposure, and the difference, or delta Ip, was taken as the measure of demineralization. The model system responded linearly to increasing concentrations of fluoride in a series of standard dentifrice preparations. Mentadent, a fluoride toothpaste with baking soda and peroxide, was shown to reduce enamel demineralization and to provide protection comparable to a clinically tested dentifrice (Crest Regular). These results established the validity of the delta Ip method, and demonstrated the efficacy of Mentadent according to the criteria established at the ADA Consensus Conference on Intraoral Models in 1990.

Role of models in assessing new agents for caries prevention - non fluoride systems
Roberts AJ
Adv Dent Res 1995, 9: 304-311

While fluoride is an effective anti-caries agent, the search for more effective alternative therapies continues. A wide range of non-fluoride anti-caries agents has been postulated, and this paper reviews some of the pre-clinical models that have been utilized in their evaluation and some of the pitfalls that must be avoided. Using data on the potential anti-caries efficacy of phosphopeptides obtained from casein, the caution that must be applied in extrapolating laboratory data to predict clinical performance is discussed. Evaluation strategies that focus on only one potential mode of action (e.g., inhibition of demineralization) may overestimate the true clinical efficacy which may arise from a combination of two or more effects (e.g., inhibition of demineralization and stimulation of remineralization). Although laboratory and in situ data predict anti-caries efficacy for sodium trimetaphosphate in combination with fluoride, this was not found in three-year clinical trials. A possible reason for this, the lack of suitable calibration methods, is discussed. Finally, some comments on the appropriateness of laboratory evaluation strategies are made.

Preparation and measurement of artificial enamel lesions, a four-laboratory ring test
ten Cate JM*, Dundon KA, Vemon PG, Damato FA***, Huntington E, Exterkate RAM*, Wefel JS***, Jordan T, Stephen KW**, Roberts AJ (*ACTA, Amsterdam, Holland **Glasgow Dental Hospital & School, Scotland, UK ***University of Iowa, USA)
Caries Res 1996, 30, 400-407

Transversal microradiography is the most widely accepted method used to study changes in mineral content profiles. In spite of its widespread use, relatively little information is available on its validity and reproducibility. Following the recommendation of the Consensus Conference on Intraoral Model Systems, this study was designed to explore reproducibility of lesion analysis within a laboratory and comparability of analysis among various laboratories. Incipient enamel lesions were produced by four research groups using both a common (‘standard’) and a local (‘preferred’) protocol. Sections were produced by each group and allocated to ‘mixed’ bags of specimens, which were analysed by the groups. With the chosen scheme some sections were analysed six times by the same group (as an internal reference standard) while others were analysed by all four groups. The data for the mineral content profiles were expressed as the integrated mineral loss (IML) value and lesion depth. The results showed the lesions produced with the standard protocol to be in the range 2,000-3,000 vol% mineral x µm for IML. The IML of the lesions produced with the preferred protocol varied between 1,800 and 6,300 vol% mineral x µm. Variation in IML values could be attributed to the biological variation between lesions, but also to time (of microradiograph production) and measurement effects, calibration of the magnification of the specimens, and the parameters used in the algorithm to calculate IML. Some of these parameters also affected the lesion depth. It is advised to standardise (or at least report) the method of calculation of IML, and to include a reference lesion between analyses in a longitudinal study as an internal standard. With the data produced, it was calculated that the number of lesions required to differentiate between preventive treatments varied substantially among laboratories. The recommendations given will improve the power of the screening methods for caries-preventive agents for which microradiography is an essential analytical method

An in vitro enamel-biofilm model: Development and sucrose dose response
Lynch RJM, Hodgson R, Barlow JA, Green AK
Caries Res 1997, 31, 294

A mechanism for the anti caries action of fluoride
Ingram GS and Nash PF
Caries Res 1980, 14, 298-303

The action of the fluoride ion has been investigated using calciumdeficient hydroxyapatites with compositions comparable with dental mineral. Whereas during carious dissolution there is a preferential loss of calcium by the mineral, the action of fluoride is to cause a preferential acquisition of calcium by the calcium deficient mineral. The calcium V:V phosphorus ratio of material acquired by suspended hydroxyapatite on addition of fluoride was always in excess of the theoretical 1.67 for hydroxy- or fluorapatite and this is consistent with a selective uptake of calcium by the depleted mineral.

Calorimetric studies of the interaction between hydroxyapatite and certain anions in aqueous solution
Benton DP*, Bullock JI*, de Namor AFD* and Ingram GS
(*University of Surrey)
Caries Res 1980, 14, 110-114

A reaction calorimeter has been used to measure heats of interaction between hydroxyapatite and a number of ionic species in solution. The technique has demonstrated substantial differences in heat output between fluoride and monofluorophosphate when interacting with hydroxyapatite. It was also possible to detect competition in reaction systems and thereby obtain information regarding reaction mechanisms.

IMAGEM 3

Influence of anatomical site on fluoride levels in rat molars
Weatherell JA*, Robinson C* and Best JS
(*University of Leeds)
Caries Res 1981, 15, 386-392

Measurement of fluoride concentrations in rat molars indicates that several areas of the dentition might be inaccessible to extraneous ions. In rats of all ages, much of the enamel, situated below the gingival margin, in occluded approximal regions or within the fissures might be unavailable to agents administered topically or otherwise. The paper discusses sampling the enamel surface of rat molars in the light of these findings.

A chemical and histological study of artificial caries in human dental enamel in vitro
Ingram GS and Silverstone LM*
(*University of lowa)

Caries Res 1981,15, 393-398 A method is described for the preparation of caries-like lesions in human enamel using a short column of methyl cellulose gel to restrict demineralisation by lactate buffer. The procedure permits the analytical determination of the ions leaving the enamel. It is found that there is a preferential removal of calcium compared to phosphorus and this is interpreted in terms of a calcium-deficient hydroxyapatite system. The lesions produced show the apparently intact surface zone characteristic of the early carious lesion. Ground sections, when examined by polarised light, show a surface zone with 1-5% pore volume over a more extensively demineralised main body of the lesion. Only the dark zone was missing in sections examined after imbibition with quinoline.

The chemistry of caries lesion formation in vitro
Ingram GS
J Dent Res 1983, 62, 460

Anti caries action and activity of fluoride and monofluorophosphate
Ingram GS and Best JS
J Dent Res 1983, 62 (special issue), 235

Chemical changes in the tooth surface and sub surface during lesion formation
Ingram GS From Demineralisation and Remineralisation of the Teeth, Edited by SA Leach and MW Edgar IRL Press, Oxford, 1983, 243-251

Artificial caries lesion formation has been monitored by measuring the amounts of calcium, magnesium and phosphate removed during the attack. It is observed that there are considerable differences in tooth susceptibility. The changes are interpreted in terms of formation of calcium-deficient apatites. Evidence is presented that part of the action of fluoride is attributable to its inducing re-acquisition of calcium by the depleted mineral, in addition to crystal growth.

Influence of monofluorophosphate treatment on the early carieslike lesion
Ingram GS and Mellor-Chrimes CP
Caries Res 1985,19,169

A scanning electron microscope study of artificial caries lesion formation
Ingram GS and Fejerskov O* (*Royal Dental College, Aarhus, Denmark)
Caries Res 1986, 20, 32-39

Little is known about very early structural changes in human enamel during carious attacks. For this reason a scanning electron microscope study was conducted on discrete artificial lesions created under chemically controlled conditions using a lactate buffer system for up to four weeks. The loss of calcium and phosphorus varied extensively from specimen to specimen. About 7 µg or more calcium had to dissolve from a 1.77-mm2 area to produce a white spot lesion. It was not possible to distinguish in the scanning electron microscope between control and experimental areas. Any structural changes induced by this simulation of a very early caries attack were masked by developmental variations and imperfections. This variability necessitates standardisation on selected tooth surfaces.

Influence of alkali-insoluble versus water-insoluble fluoride on subsequent crystal growth of hydroxyapatite
Ingram GS and Morgan SN
Caries Res 1986, 20,153

Assessment of cariogenic potential of strep mutans strains
MacPherson LMD*, MacFarlane TW*, Geddes DAM**, Lindsay JCB** and Primrose J* (*Oral medicine and Pathology, **Oral Biology group, University of Glasgow Dental Hospital and School, Glasgow, UK)
J Dent Res 1988, 67, 675

Estimations of the oral distribution and daily growth yield of streptococcus mutans in the human mouth
Tanzer JM* and Olsson J** (*University of Connecticut Health Center, Farmington, Conn., USA) (**University of Göteborg, Sweden) Caries Res 1988, 22, 118

Demineralisation of shark enamel in vivo
Ogaard P*, Arends J*, Rolla G* and Cancro LP (*Dental Faculty, University of Oslo, Norway) (**Dental Faculty, University of Groningen, The Netherlands)
Caries Res 1988, 22,125

A chemical and histological study of root surface caries produced in vitro
Ingram GS, Fejerskov O* (*Royal Dental College, Aarhus, Denmark)
Caries Res 1988, 22, 92

Effects of fluoride treatment on the demineralisation of teeth in vitro
Page DJ, Lynch R and Duckworth RM
J Dent Res 1989, 68, 888

Effects of zinc salts on F uptake to sound and demineralised enamel
Raven SJ, Horay CP, Gilbert RJ and Stead WJ
Caries Res 1990, 24, 407

The profile of biological and chemical properties of a dentifrice which contains pyrophosphate ions
Page DJ, Gilbert RJ, Horay CP, Raven SJ and ten Cate JM* (*Academic Centre for Dentistry, University of Amsterdam, Amsterdam)
Caries Res 1990, 24, 398

Interaction of zinc with dental mineral
Ingram GS, Horay CP and Stead WJ
Caries Res 1992, 26, 248-253

As some currently available toothpastes contain zinc compounds, the reaction of zinc with dental mineral and its effect on crystal growth rates were studied using three synthetic calcium-deficient hydroxyapatites (HAP) as being representative of dental mineral. Zinc was readily acquired by all HAP samples in the absence of added calcium, the amount adsorbed being proportional to the HAP surface area; about 9 µmol Zn/m2 was adsorbed at high zinc concentrations. As zinc was acquired, calcium was released, consistent with 1:1 Ca:Zn exchange. Soluble calcium reduced zinc uptake and similarly, calcium post treatment released zinc. Pretreatment of HAP with 0.5 mM zinc reduced its subsequent ability to undergo seeded crystal growth, as did extracts of a toothpaste containing 0.5% zinc citrate, even in the presence of saliva. The reverse reaction, i.e. displacement of adsorbed zinc by salivary levels of calcium, however, indicates the mechanism by which zinc can reduce calculus formation in vivo by inhibiting plaque mineralisation without adversely affecting the anti-caries effects of fluoride.

Investigation of the shrinkage of root caries lesions by electron microscopy and microradiography
Duckworth RM, Lynch RJM and Reid JD
Caries Res 1993, 27, 219

Laboratory Studies

Studies on the cariostatic mechanisms of fluoride
Shellis RP* and Duckworth RM (*Medical Research Council, Dental Research Unit, Bristol, UK)
Int Dent J 1994, 44, 263-273

This paper reviews mechanisms underlying the caries-preventive effects of fluoride, with special reference to factors which govern the efficacy of topical treatments. Fluoride reduces demineralisation in several ways: by reducing bacterial acid production and acidurance; by reducing the equilibrium solubility of apatite; and by the fluoridation of apatite crystal surfaces, reducing the dissolution rate, whether or not there is reduced solubility of the bulk mineral. On available evidence, the last seems to be the most important effect. The effect depends upon the presence of sufficiently high, dissolved fluoride concentrations to maintain the surface fluoridation. The provision of dissolved fluoride is the key to successful therapy, especially topical treatments. Fluoride also promotes remineralisation even at low concentrations, thus slowing or preventing overall mineral loss. The formation of intra-oral fluoride reservoirs capable of supplying ions for a prolonged period is crucial to the success of topical treatments. Such reservoirs include calcium fluoride, formed mainly at tooth surfaces, and fluoride associated with organic components of plaque and oral soft tissues. The patterns of fluoride clearance from intra-oral reservoirs are discussed. Fluoride may be present in dentifrices as the fluoride ion (F–) or as the monofluorophosphate ion (FPO23–). It is concluded that the efficacy of FPO23– probably depends on enzymic hydrolysis to F–. Monofluorophosphate appears to be retained less well in intra-oral fluoride reservoirs and reasons for this are discussed.

IMAGEM 4

Anticaries mode of action of casein derived phosphopeptides
Roberts AJ, Taylor CA, Littlewood DT and Horay CP
J Dent Res 1994, 73, 385

An in vitro enamel biofilm model: Development and sucrose dose response
Lynch RJM, Hodgson R, Barlow JA, Green AK
Caries Res 1997, 31,294

A most probable number method for estimation of aciduric and acidogenic bacterial populations
Atherton SE, Morgan R, Watson GK, Allison C Caries Res 1997, 54, 298 Investigation of the aciduric microflora of plaque Brailsford SR*, Byrne RW*, Adams S, Zoitopoulos L, Allison C and Beighton D* (*Kings College Dental School, London)
Caries Research 1999;33:290

Microflora of discrete, noncavitated occlusal sites.
Sheehy E*, Brailsford SR*, Clark DT*, Kidd EAM*, Adams S, Allison C, Zoitopoulos L* and D Beighton* (*Kings College Dental School, London)
Caries Research 1999;33:290

Genotypic characterisation of aciduric streptococcus oralis in dental plaque
Alam S*, Brailsford SR*, Zoitopoulos L*, Sheehy E*, Kidd EA*, Adams S, Allison C and D. Beighton* (*Kings College Dental School, London)
Caries Research 2000;34:319

Aciduric flora of active root caries lesions
Brailsford SR*, Shah B*, Gilbert SC*, Clark D* , Simons D*, Adams S, Allison C and Beighton D* (*Kings College Dental School, London)
J Dent Res 79: 664 , (special issue). SI 2000

Genotypic heterogeneity of streptococcus oralis and distinct aciduric subpopulations in human dental plaque
Alam S*, Brailsford SR*, Adams S, Allison C, Sheehy E*, Zoitopoulos L*, Kidd EA* and Beighton D* (*Kings College Dental School, London)
Applied and Environmental Microbiology 66: (8) 3330-3336 AUG 2000

The genotypic heterogeneity of Streptococcus oralis isolated from the oral cavity was investigated using repetitive extragenic palindromic PCR. Unrelated subjects harbored unique genotypes, with numerous genotypes being isolated from an individual. S, oralis is the predominant aciduric bacterium isolated from non-carious tooth sites. Genotypic comparison of the aciduric populations isolated at pH 5.2 with those isolated from mitissalivarius agar (MSA) (pH 7.0) indicated that the aciduric populations were genotypically distinct in the majority of subjects (chi(2) = 13.09; P = 0.0031). Neither the aciduric nor the MSAisolated strains were stable, with no strains isolated at baseline being isolated 4 or 12 weeks later in the majority of subjects. The basis of this instability is unknown but is similar to that reported for 12 Laboratory B Studies Unilever Dental Research Streptococcus mitis. Examination of S. oralis strains isolated from cohabiting couples demonstrated that in three of five couples, genotypically identical strains were isolated from both partners and this was confirmed by using Salmonella enteritidis repetitive element PCR and enterobacterial PCR typing. These data provide further evidence of the physiological and genotypic heterogeneity of non-mutans streptococci. The demonstration of distinct aciduric populations of S. oralis implies that the role of these and either non-mutans streptococci in the caries process requires reevaluation.
Streptococcus mitis. Examination of S. oralis strains isolated from cohabiting couples demonstrated that in three of five couples, genotypically identical strains were isolated from both partners and this was confirmed by using Salmonella enteritidis repetitive element PCR and enterobacterial PCR typing. These data provide further evidence of the physiological and genotypic heterogeneity of non-mutans streptococci. The demonstration of distinct aciduric populations of S. oralis implies that the role of these and either non-mutans streptococci in the caries process requires reevaluation.

Fluoride update to demineralised enamel: A comparison of sampling techniques
Duckworth RM, Lynch RJM
Caries Res., 32 :(6) 417-421 Nov- Dec 1998

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. Fluoride uptake is a recognised way of assessing the potential anticaries efficacy [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 20 mu l acid and the resulting solutions analysed for F. Mean F uptakes [mu g 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.

The effect of calcium glycerophosphtae on lactate production by oral streptococci measured using NMR spectroscopy
Hodgson RJ, Saul C
Caries Res: 34, abs 70, p 332

The effect of calcium glycerophosphate on the demineralisation of enamel in an in vitro bacterial flow-cell
Lynch RJM, Hodston RJ and Barlow JA
Caries Res: 34, abs 70 p332

An in vitro microbial mineralisation model
Weader E and Joiner A
J Dent Res, 2000, 79, 1190

Anti-caries efficacy of a novel dual-component toothpaste containing sodium fluoride.
Calabrese G, Parotti L, Schäfer F
J Dent Res 77: 843-843 (Abstr. 1689) (special issue) B, 1998

Depth penetration and detection of pH gradients in biofilms by two-photon excitation microscopy.
Vroom JM*; De Grauw KJ*, Gerritsen HC*, Bradshaw DJ, Marsh PD**, Watson GK; Birmingham JJ and Allison C (*University of Utrecht, The Netherlands) (**Leeds Dental Institute, Leeds, UK)
Applied and environmental microbiology (UNITED STATES) Aug 1999, 65 (8) p3502-11

Deep microbial biofilms are a major problem in many industrial, environmental, and medical settings. Novel approaches are needed to understand the structure and metabolism of these biofilms. Two-photon excitation microscopy (TPE) and conventional confocal laser scanning microscopy (CLSM) were compared quantitatively for the ability to visualize bacteria within deep in vitro biofilms. pH gradients within these biofilms were determined by fluorescence lifetime imaging, together with TPE. A constant-depth film fermentor (CDFF) was inoculated for 8 h at 50 ml. h(-1) with a defined mixed culture of 10 species of bacteria grown in continuous culture. Biofilms of fixed depths were developed in the CDFF for 10 or 11 days. The microbial compositions of the biofilms were determined by using viable counts on selective nd nonselective agar media, diverse mixed-culture biofilms developed, including aerobic, facultative, and anaerobic species. TPE was able to record images four times deeper than CLSM. Importantly, in contrast to CLSM images, TPE images recorded deep within the biofilm showed no loss of contrast. The pH within the biofilms was measured directly by means of fluorescence lifetime imaging, the fluorescence decay of carboxyfluorescein was correlated with biofilm pH and was used to construct a calibration curve. pH gradients were detectable, in both the lateral and axial directions, in steady-state biofilms. When biofilms were overlaid with 14 mM sucrose for 1 h, distinct pH gradients developed. Microcolonies with pH values of below pH 3.0 were visible, in some cases adjacent to areas with a much higher pH (>5.0). TPE allowed resolution of images at significantly greater depths (as deep as 140 microm) than were possible with CLSM. Fluorescence lifetime imaging allowed the in situ, real-time imaging of pH and the detection of sharp gradients of pH within microbial biofilms

Clinical Studies

A three-year clinical trial into the effect of fluoride content and toothpaste abrasivity on the caries inhibitory properties of a dentifrice
Murray J* and Shaw L** (*Dental School, University of Newcastle-on-Tyne) (**Dental School, University of Birmingham)
Comm Dent Oral Epidemiol 1980, 8, 46-51

The effect of reducing the abrasivity of toothpaste on dental caries was observed in a three-year clinical trial involving 1106 11-13 year-old Berkshire schoolchildren. The children were divided into three groups; Group 1 were allocated a low abrasivity paste containing 0.8 per cent sodium monofluorophosphate, Group 2 a paste of conventional abrasivity also containing 0.8% sodium monofluorophosphate and Group 3 a low abrasivity non-fluoride paste. After three years the net DMFS increments (clinical and radiographic scores combined) were 4.22 in Group 1, 4.72 in Group 2 and 6.43 in Group 3. The differences between Groups 1 and 3 and between Groups 2 and 3 were highly significant (p<0.001). The mean increment in Group 1 was lower than in Group 2 but did not reach statistical significance. Reducing the abrasivity of the toothpaste had no meaningful effect on the standard of oral hygiene and prevalence of gingivitis as measured by the Gingival and Plaque Indices.

IMAGEM 4

Methods of preventing dental caries used by dentists for their own children
McDonald SP*, Cowell CR and Sheiham A** (*City and East London AHA) (**London Hospital Medical College)
Brit Dent J 1981,151, 118-121

The relative effectiveness of different methods of caries prevention in dentists own children was compared. Dietary restriction of sugar was found to not only enhance other methods but to be the most effective single method of prevention and be an essential part of regimen aimed at achieving a caries-free state.

Clinical investigation of the effects of dentifrices on dentine wear at the cemento-enamel junction
Saxton CA and Cowell CR
J Am Dent Assoc 1981, 102, 38-43

A two year clinical study was conducted in vivo to assess the dentine wear caused by dentifrices. The results were correlated and compared with those obtained in vitro. This series of studies has shown that a similar ranking of dentifrice abrasivity, according to either BSI or ADA laboratory methods, can be shown to occur in the mouth. However the influence of abrasivity on loss of dentine is much smaller than the laboratory prediction and the contribution of dentifrice abrasivity per se is not the major factor in the progression of cervical lesions

Toothbrushing attitudes and behaviour of 12 and 13-year-old Somerset children
Palmer JD*, Burchell CK and Andlaw RJ** (*Somerset Area Health Authority) (**University of Bristol Dental School)
Health Education J 1981, 40, 79

A questionnaire survey on toothbrushing attitudes and behaviour of 1158 Somerset children aged 12-13 years is reported, this survey being part of a three-year toothpaste clinical trial. The results indicate that the majority of these children do brush their teeth regularly each day, but there is a need to emphasise more thorough brushing of all tooth surfaces and the gingival margins for effective oral hygiene. The concern of this age group for ‘social acceptability’ should be an important consideration in designing dental health educational material for young teenagers.

Comparison of dental health of 11 year-old children in 1970 and 1979 and of 14 year-old children in 1973 and 1979, studies in Bristol
Andlaw RJ* Burchell CK and Tucker GJ** (*University of Bristol Dental School) (**Avon Area Health Authority)
Caries Res 1982,16, 257-264

The purpose of the study was to compare the dental health of 11 year-old and 14 year-old children in three Bristol schools with that of children of the same ages who attended the same schools and participated in a 14 Unilever Dental Research clinical trial from 1970 to 1973. The children were examined by the same two clinicians who conducted the clinical trial. The results showed marked reductions in dental caries experience. The reductions of mean DMFT and DMFS of 11 year-old children from 1970 to 1979 were 36 and 41%, respectively, and of 14-year-old children from 1973 to 1979, 30 and 36% respectively. The reason for these reductions is unknown, but it is noted that they occurred during a period when the use of toothpastes containing fluoride increased markedly.

The anti-caries effect of supervised toothbrushing with a non-fluoride dentifrice
Fogels HR*, Cancro LP, Bianco J and Fischman SL** (*Tufts University, Boston, USA) (**State University of New York at Buffalo)
J Dent Child 1982, 49, 424-427

The benefits derived from toothbrushing without the therapeutic benefits of fluoride are shown. A total of 109 children participated in daily one-minute classroom toothbrushing drills, using non-fluoridated toothpaste, while a similar number of subjects used their own fluoride dentifrice on an unaltered regimen. The oneyear caries increment was lower for the classroom brushers.

Calcium and phosphorus content of plaque and saliva in relation to dental caries
Shaw L*, Murray JJ**, Burchell CK and Best JS (*University of Birmingham Dental School) (**University of Newcastle Dental School)
Caries Res 1983,17, 543-548

Plaque and saliva samples were obtained from 55 children aged 13-I5 years: 23 of them were caries free (group N), while the other 32 had evidence of high-caries activity over the preceding two years, with a mean DMFS of 25.9 (group H). The average concentration of calcium in posterior plaque of children in group N was 3.57μg/mg (dry weight) compared with 1.63 μg/mg for group H. The average concentration of calcium in anterior plaque was 11.55μg/mg in group N and 2.57μg/mg in group H. The differences between groups N and H were statistically significant (p<0.01). Similar significant differences were found between phosphorus levels in plaque. Although the mean levels of both calcium and phosphorus in saliva were higher for group N than for group H, only for phosphorus did the difference reach statistical significance (p<0.05). The present study therefore shows that levels of both calcium and phosphorus are significantly higher in plaque taken from children with no caries experience than they are in plaque from children who are caries susceptible.

Caries preventive effects of toothpaste containing monofluorophosphate and trimetaphosphate: a three-year clinical trial
Andlaw RJ*, Palmer DJ**, King J* and Kneebone SB** (*University of Bristol Dental School) (**Somerset Health Authority)
Comm Dent Oral Epidemiol 1983, 11, 143-47

The caries-preventive effects of two toothpastes were tested in a threeyear clinical trial involving 1319 children aged 11-13 years. The test toothpastes were: 1) a low abrasion paste containing 0.8% sodium monofluorophosphate (MFP), and 2) a paste containing 3%sodium trimetaphosphate (TMP). The control toothpaste was a conventional, moderately abrasive paste containing 0.8% sodium monofluorophosphate. The children were examined clinically and radiologically each year. Toothpaste was supplied to the children’s homes, and its use was unsupervised. Caries increments after three years, in terms of DMF teeth and DMF surfaces, showed no significant differences between the MFP test group (444 children) and the MPF control group (450 children). However, the TMP test group (425 children) had significantly higher caries increments than the MFP control group. All three groups of children showed some improvement in oral hygiene and in gingival health, but there were no significant differences between the groups.

Changes in caries prevalence of children on the Isle of Lewis between 1971 and 1981
Hargreaves JA*, Thompson GW* and Wagg BJ (*University of Alberta)
Caries Res 1983,17, 554-559

An increasing body of evidence suggests that dental caries prevalence among children and adolescents in the UK, some continental European countries and the US has shown a marked reduction in the past decade. Prevalence data collected from a 1971 survey conducted on children aged five, eight, 11 and 14 years living on the Isle of Lewis (Scotland) has been compared with contemporary (1981) data from the same age groups in this community. In this island, there is little change or movement of population and a complete record of dental health measures over the past ten years is available. The results confirm the general decrease found in the other localities mentioned. There is no fluoride in the drinking water and no appreciable use of fluoride rinses or tablets in this community. However, the toothpaste market has changed over the period from zero fluoride in 1970 to virtually 100% fluoride by 1976.

Caries prevention using a 1.2 per cent sodium monofluorophosphate dentifrice in an aluminium oxide trihydrate base
Hanachowicz L* (*Union Francaise pour le Sante Bucco Dentaire, Paris)
Comm Dent Oral Epidemiol 1984, 12, 10-16

A three-year clinical trial was carried out in France just after fluoride toothpaste was allowed to be sold on the mass market. The aim was to assess the caries preventive effect of a toothpaste containing the maximum fluoride level permitted by the EEC (1.2 per cent SMFP). The trial started with 1318 10 12-year-old children from a wide socioeconomic background in a typical French community. Test toothpaste was given to 659 children whereas the remaining 659 children obtained the same toothpaste without the fluoride additive. The brushing was unsupervised and performed by the children at home. Dental caries was assessed by clinical and radiographic examinations. 1061 children completed the trial. An interview carried out at the final examination identified a group of 116 unco-operative children (less than five brushings a week on average) who were not included in the statistical analysis. The following mean reductions were found: 26% for DMFT, 27% for DMFS and 39% for DMFSU. The DMFS index for approximal, buccallingual and occlusal surfaces showed caries reductions of 32%, 25% and 22%, respectively. The trial demonstrated a highly significant effectiveness of the 1.2% SMFP toothpaste in a French population.

IMAGEM 5

Caries inhibition of a dentifrice containing 0.78 per cent sodium monofluorophosphate in a silica base
Rule JT*, Smith MR** True/ove RB*, Macko DJ*** and Castaldi C*** (*Dental School, Baltimore, Maryland) (**Michigan Technological University) (***University of Connecticut)
Comm Dent Oral Epidemiol 1984,12, 213-217

The purpose of this double blind clinical trial was to determine the anticaries activity of a dentifrice containing 0.78 per cent sodium monofluorophosphate in a silica gel abrasive base compared with a placebo under conditions of supervised brushing. 1154 schoolchildren, ages 9-12 were recruited in a non-fluoridated semirural area of northeastern Connecticut. Subjects were stratified according to school, grade and sex, and then randomly divided into two groups. Each school day, children brushed their teeth for one minute under supervision by project personnel. Weekend and vacation usage was ad libitum. Caries examinations and radiographic readings were performed by the same examiner (JR). After 12 months the 996 subjects examined showed that the group using the test dentifrice had significantly (< 0.05) lower DMFT (25.0%) and DMFS (19.1%) increments than the group using the placebo. After 24 months the 876 subjects examined showed that the test group continued to have significantly lower DMFT (24.5 per cent) and DMFS (24.7 per cent) increments than the placebo group. Surface protection after 24 months ranged from 22.1% for occlusal to 37.1% for interproximal surfaces.

Root surface caries - a review
Wagg BJ
Community Dental Health 1984,1,11-20

The proportion of elderly persons in the population is increasing in many countries. With the emphasis on dental care being placed increasingly on measures which will encourage tooth retention, it has been suggested that root surface caries may become an increasingly important dental disease. This paper reviews the evidence to date on its identity, pathology and prevalence.

In-situ caries studies using an intraoral appliance
Creanor SL*, Telfer S*, Smith MJ*, Stephen KW* Strang R* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1985,19,178

In vivo remineralisation of artificial caries lesions by toothpastes containing 1000 or 1500 parts per million fluoride
Schafer F, Parr TA and Burchell CK
J Dent Res 1986, 65 (special issue), 781

In vivo remineralisation of artificial caries lesions by a fluoride toothpaste
Schafer F, Parr TA and Burchell CK
Caries Res 1986, 20,176

Comparisons between microbiological caries activity tests and clinical status in adolescents
Russell JI*, MacFarlane TW*, Stephen KS*, Aitchison TC* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 20,1986,170

Fluoride in plaque following use of dentifrices containing sodium monofluorophosphate
Duckworth RM, Morgan SN and Burchell CK
J Dent Res 1986, 65 (special issue), 794

Fluoride in saliva and plaque following use of fluorinecontaining mouthrinses
Duckworth RM, Morgan SN, Murray AM and Carter P
J Dent Res 1986, 65 (special issue), 781

Oral fluoride levels and ambient fluoride intake Ingram GS and Morgan SN Caries Res 1987, 21,179 Comparisons between microbiological caries activity tests and one year caries increment in adolescents
Russell JI* MacFarlane TW* Aitchison TC* Stephen KW* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1987, 21,165

Effect of monofluorophosphate concentration and 0.5 per cent zinc citrate in toothpaste on caries increments
Stephen KW*, Russell Jl*, Creanor SL* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1987, 21,162

Three-year oral health trial with zinc containing monofluorophosphate dentifrices
Stephen KW*, Creanor SL*, Russell JI*, Burchell CK and Huntington E (*University of Glasgow Dental School, Glasgow, UK) J Dent Res 1987, 66 (special issue), 164 Effect of anticaries dentifrices on orthodontic subjects Fischman S, Cancro L and D’Agostino R
J Dent Res 1987, 66 (special issue), 258

Changes in caries prevalence of Isle of Lewis UK children. A historical comparison from 1937 to 1984
Hargreaves JA* Wagg BJ and Thompson GW* (*Faculty of Dentistry, University of Alberta, Edmonton, Alberta, Canada)
Caries Res 1987, 21, 277-284

The Isle of Lewis is an island community which has little movement of its school population and since the Second World War, mirrors closely the rest of the United Kingdom in availability of foods, introduction of television and educational opportunities. One of the first major dental epidemiological studies was conducted on the island by King in 1937. Between 1968 and 1984 a further series of investigations has been conducted on this population by the present authors; these allow a comparison of caries prevalence at intervals of time over 47 years. The findings show a marked increase in dental caries from 1937 to 1971, an equally marked decrease during the remainder of the 1970s and a further modestincrease among the younger age groups studied between 1981 and 1984.

Fluoride in saliva and plaque following use of fluoridecontaining mouthwashes
Duckworth RM, Morgan SN and Murray AM
J Dent Res 1987, 66,1730-1734

The sensitivity of methodology for measuring the concentration of fluorine species in saliva and in plaque has been tested. Human subjects mouth-rinsed daily with aqueous solutions of NaF and Na2FPO3. Samples of unstimulated whole saliva and of plaque were collected twice weekly at least 18 hours after treatment application. Oral fluoride concentrations rose from placebo values for approximately two weeks before attaining equilibrium and returned to baseline when daily mouthrinsing was stopped. Mean elevated oral fluoride concentrations increased significantly with increasing applied NaF concentration in the range 0- 1000 ppm F (0-0.053 mol/L). There appeared to be a linear relationship between saliva and plaque fluoride. The ability of fluoride treatments to sustain elevated oral fluoride levels between daily applications may be of major importance in caries control.

A clinical investigation of a high-level fluoride dentifrice
Fogels HR, Meade JJ, Griffith J, Miragliudlo R and Cancro LP
J Dent Child 1988, 55, 210-215

A silica gel dentifrice containing 1500 ppm fluoride was compared to a conventional fluoride toothpaste containing 1000 ppm fluoride in a clinical trial. The clinical study was conducted over a three year period on about 2000 children. The study demonstrated that there is an anticaries benefit from using the higher fluoride dentifrice.

A three year clinical trial to compare efficacy of dentifrices containing 1.14 per cent and 0.76 per cent sodium monofluorophosphate
Conti AJ*, Lotzkar S*, Daley R**, Cancro L**, Marks RG*** and McNeal DR* (*Department of Community Dentistry, College of Dentistry, University of Florida, Gainesville, FL) (**Syntex Corp, Palo Alto, CA) (***Division of Biostatistics, Department of Statistics, University of Florida, Gainesville, FL. USA)
Community Dent Oral Epidemiol 1988, 16, 135-138

A three year daily supervised toothbrushing study with a double blind design was conducted to evaluate the anticaries effectiveness of a 1.14% sodium monofluorophosphate (MFP) dentifrice (1500ppm F) compared to a 0.76% MFP dentifrice (1000ppm F). This study began with nearly 4000 children, primarily aged 8-11, in grades 3-5, residing in a non-fluoridated community in Florida. A total of 2415 children completed three years of the study, representing 61% of the children who began the study. The results indicate a statistically significant (p<0.001) anticaries benefit was derived over a three year period from the use of the higher fluoride dentifrice (1500ppm F) when compared to the positive control (1000ppm F). Per cent reductions in mean dental caries increments were 20.9%, 22.1%, 21.8%, 24.3% and 35.2% for DMFT, DFT, DMFS and DFS Interproximal, respectively.

Dental status in a Javanese male population
Gaare D*, Rolla G* and van der Ouderaa FJG (*Dental Faculty, University of Oslo, Norway)
Caries Res 1988, 22, 94

A two-year clinical, fibre-optic transillumination, and radiographic caries study in 3000 children
Stephen KW*, Creanor SL*, Russell JI* and Burchell CK (*Department of Oral Medicine, University of Glasgow Dental Hospital and School, Glasgow, UK)
Caries Res 1988, 22,108

In vivo remineralisation of artificial caries lesions by toothpastes containing 1500 or 2500 ppm fluoride
Schäfer F, Parr TA and Burchell CK
Caries Res 1988, 22,10

A three-year oral health doseresponse study of sodium monofluorophosphate dentifrices with and without zinc citrate: anti-caries results
Stephen KW*, Creanor SL*, Russell JI*, Burchell CK, Huntington E and Downie CFA** (*University of Glasgow Dental Hospital and School, Glasgow, UK) (**Lanarkshire Health Board, Hamilton, Scotland)
Community Dent Oral Epidemiol 1988, 16:321-5

A three-year clinical trial has been conducted on 3000 12-year-old children in Lanarkshire, Scotland, with the aim of investigating the effects on oral health of toothpastes containing both sodium monofluorophosphate and zinc citrate, the former being present at fluoride levels of 1000,1500, and 2500 ppm F. No significant difference in caries increments was found between the group of children using toothpastes incorporating zinc citrate and their counterparts using zinc-free pastes. However, a significant anti-caries dose-response was demonstrated over the SMFP range used. This dose-response was evident for boys and girls and also for the various types of teeth and tooth surfaces.

Comparison of demineralization and associated microflora using intact and abraded enamel in an intraoral appliance
MacPherson LMD*, MacFarlane TW*, Stephen KW* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1989, 23, 120

On the interaction between fluoride species and oral soft tissue
Duckworth RM and Jones S
J Dent Res 1989, 68, 560

Effect of rinsing after toothbrushing on salivary fluoride and caries
Duckworth RM, Knoop DTM and Stephen KW* (*University of Glasgow Dental Hospital and School, Glasgow, UK)
J Dent Res 1989, 68, 888

Fluoride in plaque following use of dentrifices containing sodium monofluorophospate
Duckworth RM, Morgan SN and Burchell CK
J Dent Res 1989, 68, 130-133

On the relationship between salivary fluoride clearance and the rate of salivary flow
Duckworth RM and Jones S
Caries Res 1989, 23, 437-438

Oral clearance of fluoride and zinc after application of dentifrices containing sodium monofluorophosphate and zinc citrate
Duckworth RM, Jones S and Tan- Walker RLB
Caries Res 1989, 23, 119

Fluoride in plaque following use of dentifrices containing sodium monofluorophosphate
Duckworth RM, Morgan SN and Burchell CK
J Dent Res 1989, 68, 130-133

Previous work showed that plaque fluoride increased with increasing NaF content of mouthwashes following daily use. The main aim of this study was to test whether a similar relationship was detectable 18 after regular use of dentifrices containing amounts of sodium monofluorophosphate equivalent to 1000, 1500 and 2500μg F/g. Plaque was collected from three groups, each consisting of approximately 80 children, who had each used one of the dentifrices for one year. Plaque fluoride increased significantly with increasing Na2FPO3 content of the dentifrices. For the 1000μg -F/g group, plaque fluoride also increased significantly with increasing frequency of dentifrice use, but did not correlate with amount of dentifrice applied per brushing. The inverse correlation observed between mean plaque fluoride concentrations and mean three-year caries increments suggests that oral fluoride measurements may prove valuable in estimating the likely anti-caries efficacy of fluoride-containing dental products.

A cross-sectional study of DMFT and CPITN scores in a group of Indonesian soldiers
Gaare D*, Joelimar FA**, van der Ouderaa F and Rölla G* (*Faculty of Dentistry, University of Oslo, Norway) (**Department of Periodontics, Faculty of Dentistry, University of Indonesia, Jakarta)
Scand J Dent Res 1989, 97, 20-24

A cross-sectional clinical study showed that the prevalence in caries among Indonesian soldiers was low, compared with that found in corresponding Western populations. Also, the progression of caries was very slow, and caries was limited almost exclusively to the occlusal surfaces of the teeth. Among officers, the prevalence of caries was lower that it was among other ranks of the same age. The low general prevalence of caries among Indonesian soldiers may be related to diet. Rice was the major source of carbohydrate for the soldiers, and their sucrose consumption was 10kg per person per year. Their drinking water contained a low concentration of fluoride (0.1ppm). In spite of massive accumulations of calculus, the periodontal health of young soldiers (< 26 yr) was also good. Among those in higher age groups, however, periodontal health had deteriorated, but even in a group aged 40-46 year, no teeth had been lost as a result of periodontal disease. Among officers, periodontal health was better than it was amongst other ranks of corresponding age. The officers had been accustomed to brushing their teeth regularly, whereas the other ranks had not. It thus appears that toothbrushing may help to preserve periodontal health, even when large amounts of calculus are present on the teeth and there is no opportunity for it to be removed regularly by a dentist.

Evaluation of the anticaries benefit of fluoride toothpastes using an enamel insert model
Schäfer F
Caries Res 1989, 23, 81-86

The remineralization potential of fluoride toothpastes was studied using an in situ enamel insert model. Matched blocks of artificially demineralized human enamel were attached to partial dentures of 16 adult volunteers who brushed their teeth with either a toothpaste containing 500ppm F or one containing 2500ppm F for a period of six weeks in a balanced, randomized crossover experiment. Computerized image analysis of microradiographs was used to measure the mineral density distribution in the enamel before and after in situ treatment. Both toothpastes demonstrated remineralization of artificial carious lesions. Significantly more remineralization was observed in enamel samples treated with the toothpaste containing 2500ppm F compared to that containing 1500ppm F. This result is consistent with the outcome of a recent caries clinical trial testing the same toothpastes and finding enhanced anticaries efficacy from the higher fluoride level.

Site specificity of in situ enamel remineralization
Schäfer F, Raven SJ and Parr TA
Caries Res 1990, 24, 404

Effect of mouthwashes of variable NaF concentration but constant NaF content on oral fluoride retention
Duckworth RM and Stewart D
Caries Res 1990, 24, 406

Salivary levels of mutans streptococci, Lactobacillus, Candida and Veillonella species in a group of Scottish adolescents Russell JI, MacFarlane TW*, Aitchison TC*, Stephen KW* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK) Community Dent Oral Epidemiol 1990, 18, 17-21 Salivary levels of mutans streptococci, Lactobacillus, Candida, and Veillonella species were investigated on three occasions at annual intervals in a group of 372 Scottish adolescents. Counts of the micro-organisms studied were logarithmically distributed, with Candida spp. being isolated from approximately half the subjects. Counts of lactobacilli, mutans streptococci, and candida were significantly intercorrelated, while veillonella were associated consistently with mutans streptococci alone. Levels of each of the four microorganisms were significantly correlated over the three examinations, with levels of the Candida spp. being the most stable over the period studied. 19

Caries prevalence and microbiological and salivary caries activity tests in Scottish adolescents
Russell JI, MacFarlane TW*, Aitchison TC*, Stephen KW* and Burchell CK (*University of Glasgow Dental School, Glasgow, UK)
Community Dent Oral Epidemiol 1990, 18, 120-125

Salivary and microbiological caries activity tests were investigated on three occasions in a group of 372 Scottish adolescents. Counts of lactobacilli. mutans streptococci, and candida were consistently and significantly associated with caries prevalence, as either DS or DMFS score, and buffering capacity was consistently inversely related to DMFS score. However, veillonella counts and salivary flow rate were not correlated with caries prevalence. Significant improvements in the associations were obtained when the results of more than one test were included using stepwise regression analysis. On an individual basis, at most, stepwise discriminant analysis identified the DMFS group correctly in 49% of all subjects, and the DS group in 47%.

Involvement of calcium in the interaction between fluoride ions and oral soft tissue
Duckworth RM and Jones S
Caries Res 1991, 25, 223

Dental disease changes 1981- 1990 in the scottish Isle of Lewis
Hargreaves JA*, Williams SA**, Huntington E and Baylor N (*Faculty of Dentistry, University of Alberta, Edmonton, Canada **School of Dentistry, University of Leeds, UK)
Caries Res 1991, 25, 215

Oral fluoride retention After use of fluoride dentifrices
Duckworth RM and Morgan SN
Caries Res 1991, 25, 123-129

Fluoride is the only extensively clinically proven means of reducing dental caries. Despite a large body of epidemiological data on the effectiveness of fluoride, delivered in the form of dentifrices, mouthrinses, drinking water etc., the precise mode of action of fluoride is not completely understood. The purpose of this paper is to report an investigation of the link between oral fluoride levels and applied fluoride dose from dentifrices. Human salivary fluoride clearance studies and equilibrium baseline studies of fluoride in saliva and plaque have been carried out with dentifrices which contained 1000, 1500 and 2500μg fluoride per gram as sodium monofluorophosphate. After a single brushing with a fluoride dentifrice, salivary fluoride decreased in two distinct phases: an initial rapid phase which lasted for 40-80 minutes, depending on the individual, and a second slow phase lasting for several hours. The latter phase is believed to be due to fluoride released from an oral fluoride reservoir. During regular repeated use of the test dentifrices, the equilibrium baseline fluoride concentration, attained in both saliva and plaque between one application and the next, increased significantly compared with placebo values. Such elevated baseline fluoride concentrations also increased with increasing Na2FP03 content of the dentifrices. The present work supports the concept that labile fluoride, stored in an oral fluoride reservoir at the time of treatment application, may maintain a prolonged protective effect against dental caries. Effect of mouthrinsing after toothbrushing with a fluoride dentifrice on human salivary fluoride levels Duckworth R M, Knoop DTM and Stephen KW* (*University of Glasgow Dental School, Glasgow, UK) Caries Res 1991, 25, 287-291 In a recent clinical trial of sodium monofluorophosphate dentifrices, oral rinsing habits were found to influence dental caries. Thus an oral fluoride clearance study has been undertaken which was designed to test a possible mechanism for the observed effects. Eight subjects brushed with one of the trial dentifrices and then rinsed using one of eight procedures of varying thoroughness. The salivary fluoride concentration measured 5 minutes after dentifrice application decreased significantly with increasing rinse volume, rinse duration, and rinse frequency (p<0.01, analysis of variance). The area under the clearance curve determined over a further 3h was significantly higher (300%; p<0.01) following use of the least thorough rinsing procedure (5ml x 2s once) as compared with the corresponding area under the clearance curve following the most thorough procedure (20ml x 10s twice). These findings indicate that rinsing habits may play an important role in the oral retention of fluoride from dentifrices which may, in turn, affect their clinical efficacy.

Oral fluoride reservoirs and their relationship to anticaries efficacy
Duckworth RM, Morgan SN, Ingram GS and Page DJ
Clinical and Biological Aspects of Dentistry, Editor G Embery, Oxford University Press, 1992, 91-104

Studies of fluoride in saliva and plaque have shown that regular use of Na2FPO3 /alumina dentifrices results in sustained elevated fluoride concentrations compared with corresponding levels obtained during use of a non-fluoride 20 dentifrice. Other in vivo work has demonstrated that such elevated oral fluoride concentrations are associated with clinical reductions in caries for both fluoride dentifrices and fluoridated drinking water. Furthermore, in vitro studies have demonstrated the potential of sustained low levels of fluoride to influence beneficially both demineralization and remineralization processes associated with caries. There is, therefore, increasing evidence to support the concept that fluoride, stored in oral reservoirs during topical applications, can maintain a prolonged protective effect against dental caries.

IMAGEM 6

Oral fluoride measurements to estimate the anticaries efficacy of fluoride treatments
Duckworth RM, Morgan SN and Gilbert RJ
J Dent Res 1992, 71, 836-840

The aims of this work were (a) to assess the oral bioavailability of fluoride delivered from dentifrices and (b) to test for a possible link between the results and clinical data obtained with the same dentifrices. Oral fluoride concentrations were measured in samples of saliva and plaque taken from seven subjects, after use of dentifrices which contained 0, 1000, 1500, and 2500μg F/g as sodium monofluorophosphate. Salivary fluoride in samples obtained within the first few hours after a single dentifrice application, or up to 20h after four weeks’ daily use, increased with increasing F content of the dentifrice. For example, the mean zero-time intercepts of the second phase of salivary fluoride clearance curves for the above dentifrices were 0.46, 1.48, 1.88, and 3.03μmol F/L, respectively. Plaque fluoride measured after four weeks daily use of the dentifrices exhibited similar dose-response behaviour. Linear regression analysis showed these trends to be statistically significant for both saliva (p<0.001) and plaque (p<0.025). Mean saliva and plaque fluoride concentrations were inversely associated with mean three-year caries increments for the three fluoride-containing dentifrices obtained in a recent clinical trial: DMFS scores 6.80, 6.33, and 5.71, respectively (Stephen et al., 1988). This suggests that oral fluoride measurements are a valuable in vivo method for the evaluation of the potential anti-caries efficacy of fluoride-containing dental products.

Fluoride in plaque after regular use of dentifrices containing different fluoride sources
Duckworth RM, Nicholson J, Jacobson APM* and Chestnutt IG* (*University of Glasgow Dental School, Glasgow, UK)
J Dent Res 1992, 71, 521

Residual volume determinations
Page DJ, Chestnutt IG*, Jacobson APM*, Schäfer F, Huntington E, Stephen KW* and Chesters RK (*University of Glasgow Dental School, Glasgow, UK)
J Dent Res 1992, 71, 644

Effect of oral care habits on caries in adolescents
Chesters RK, Huntington E, Burchell CK and Stephen KW* (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1992, 26, 299

The science behind caries prevention
Duckworth RM
Int Dent J 1993, 43, 529-539

Many agents have been shown to have an anticaries effect or to have the potential for such an effect. They can be categorised by their modes of action into three groups: those which affect plaque and plaque bacteria, those which affect tooth enamel chemistry and those which buffer oral pH. To be effective clinically, agents must not only possess intrinsic efficacy but also good oral retention characteristics. Currently, chlorhexidine is arguably the only antibacterial agent to have inhibited caries in humans, but is not employed in anticaries dentifrices and mouthrinses intended for longterm unsupervised daily use because of formulation difficulties and undesirable side effects such as tooth stain. Certain calcium salts and Xylitol may also exert some clinical effect. The only extensively clinically-proven agent is fluoride. Well established reasons for the success of fluoride are its abilities to inhibit demineralisation of enamel and to enhance the remineralisation of incipient caries lesions. Recent research has highlighted the persistence of fluoride in saliva and plaque at potentially-active concentrations between successive regular applications of dentifrices and mouthrinses as a further important mechanistic step. Oral fluoride retention studies can explain recent clinical observation of increased efficacy of sodium fluoride dentifrices compared with sodium monofluorophosphate dentifrices of equivalent fluoride content.

Fluoride in plaque and saliva
Duckworth RM
Thesis 1993, University of Amsterdam, Amsterdam, the Netherlands, Haveka B.V., Alblasserdam, the Netherlands

The thesis describes work aimed at increasing understanding of oral fluoride retention. The work was conducted by the author over several years at Unilever Dental Research under the auspices of Prof. J M ten Cate of ACTA, University of Amsterdam. The main focus concerns in vivo studies of short term clearance and long term build up of fluoride in plaque and saliva during and after use of fluoride-containing mouthwashes and dentifrices. Important aspects of the work were done in conjunction with a three-year caries clincial trial of a series of dentifrices of different F content. The potential role of the oral soft tissues as an oral fluoride reservoir was identified from in vitro studies. The results highlight the importance for the control of dental caries of maintaining an elevated level of fluoride in the mouth by regular use of topical fluoride treatments.

The effect of calcium carbonate dentifrices on plaque pH
Preston AJ*, Gibbs C, Vernon P, Huntington E and Edgar WM* (*University of Liverpool Dental School, Liverpool, UK)
J Dent Res 1993, 72, 720

Relationship between caries and toothbrushing habits in Scottish adolescents
Schäfer F, Chestnutt IG*, Jacobson APM* and Stephen KW* (University of Glasgow Dental School, Glasgow, UK)
Caries Res 1993, 27, 229

Toothbrushing frequency and dental caries in areas with ‘low’ fluoride and fluoridated water
Ellwood RP*, O’Mullane DM* and Chesters RK (University College of Cork, Ireland)
Caries Res 1993, 27, 222

Effect of NaF and SMFP dentifrices on three year caries increments
Stephen KW*, Chestnutt IG*, Jacobson APM*, Chesters RK, Schäfer F and Huntington E (*University of Glasgow Dental School, Glasgow, UK)
J Dent Res 1993, 72, 346

Salivary fluoride clearance studies with a novel high fluoride retention mouthwash
Duckworth RM, Haley JA and Jones Y
J Dent Res 1993, 72, 271

Effect of mouthwashes of variable NaF concentration but constant NaF content on oral fluoride retention
Duckworth RM and Stewart D
Caries Res 1994, 28, 43-47

Previous work showed that oral fluoride levels increased with increasing applied F dose mouthwashes and dentifrices. This study aimed to determine whether the above dependence was related to applied fluoride concentration or applied fluoride amount. Ten adults mouthrinsed with aqueous NaF solutions of 1-10ml. each of which contained 2.5mg F, i.e. in the concentration range 250- 2,500ppm F. Subjects rinsed for one minute then spat out. Samples of mixed saliva were collected for 3 hours afterwards, which were analysed for fluoride. Salivary fluoride clearance curves were obtained which could be fitted to a pharmacokinetic model involving processes ascribed to loss of fluoride from saliva by swallowing and to exchange of fluoride between saliva and an oral reservoir. Mean salivary fluoride concentrations increased significantly with increasing applied F concentration both within the first 3h after single use and up to at least 18h after regular daily use. These findings suggest that applied F concentration is a more important factor than applied F amount per se in determining the elevation of oral fluoride levels following topical fluoride use. This implies that application of a given F dose, in a smaller volume at higher concentration than the current norm, may increase efficacy without increasing the risk of adverse effects.

Effect of various levels of fluoride (NaF) on the demineralisation of enamel in situ
Dundon KA, Huntington E, Morrison T and Roberts AJ
Caries Res 1994, 28, 201

Studies on plaque fluoride after use of F-containing dentifrices
Duckworth RM, Jones Y, Nicholson J, Jacobson APM* and Chestnutt I* (University of Glasgow Dental School, Glasgow, UK)
Adv Dent Res 1994, 8, 202-207

Increased fluoride levels in plaque and saliva have been associated with improved protection against dental caries for dentifrices which contained sodium monofluorophosphate (Duckworth et al.,1992). The main aim of the present work was to test whether oral fluoride retention depended on F source after use of dentifrices containing either NaF or Na2FPO3. In Study 1, plaque samples were collected from 474 subjects who had been using one of six test dentifrices for two years, and analyzed by F extraction with water. The dentifrices contained 1000 or 1500μg F/g as either NaF or Na2FPO3. Significantly more fluoride was found in plaque from subjects who were using the NaF dentifrices than in plaque from subjects who were using Na2FPO3 dentifrices of the same F content. Subsets of plaque samples were large enough to divide into two parts for extraction by both acid and water. No significant difference was found between mean fluoride contents, indicating that the majority of fluoride retained in plaque from these conventional dentifrices appears to be relatively labile. The results of two small- 22 scale human enamel studies

Contribution of different surface types to three-year caries increments
Jones PR, Kavanagh D*, Ellwood RP*, O’Mullane DM* and Chesters RK (*University College of Cork, Ireland)
Caries Res 1994, 28, 194

Prevalence of recurrent caries in adolescents
Chestnutt IG*, Jones PR, Jacobson APM* and Stephen KW* (*University of Glasgow Dental School, Glasgow, UK)
Caries Res 1994, 28, 195

Susceptibility of tooth surfaces to dental caries in Scottish adolescents
Chestnutt IG*, Schäfer F, Jacobson APM*and Stephen KW* (*University of Glasgow Dental School, Glasgow, UK)
J Dent Res 1994, 73, 789

Association between toothbrushing routines and caries increments in a clinical trial
O’Mullane DM*, Ellwood RP*, Kavanagh D*, Chesters RK and Schäfer F (*University College of Cork, Ireland)
Caries Res 1994, 28, 195

25 years of caries studies in the Isle of Lewis
Hargreaves JA*, Baylor N and Huntington E (*Faculty of Dentistry, University of Alberta, Edmonton, Alberta, Canada)
Caries Res 1994, 28, 181

Investigation of calcium carbonate dentifrice using plaque sampling and touch electrode pH methods
Preston AJ*, Gibbs C, Huntington E and Edgar WM* (*University of Liverpool Dental School, Liverpool, UK)
Caries Res 1994, 28, 188

IMAGEM 7

The effect of a calcium carbonate dentifrice on plaque pH in schoolchildren
Preston AJ*, Gibbs C, Huntington E and Edgar WM* (*University of Liverpool Dental School, Liverpool, UK)
J Dent Res 1994, 73, 845

Levels of cystatin in whole saliva of children: Association with oral health status
Tabak LA*, Bowen WH*, van Wuyckhuyse B*, Frank D*, Bessette J*, Page DJ, Taylor CA, Green AK, Huntington E and Roberts AJ (*Rochester Cariology Centre and University of Rochester, NY, USA)
Caries Res 1994, 28, 182

Test of a dentifrice in the intraoral delta Ip model system
Mengshoell K*, Kashket S*, D’Agostino R*, Stepanians M*, Cancro L (*Forsyth Dental Centre, Boston University, USA)
J Dent Res 1994, 73, 272

Posterior interproximal caries detection by FOTI vs radiology in the clinical setting
Stamm J*, Cortes D**, Clem D***, Chesters RK (*University of North Carolina, USA, **Sao Paulo University, Brazil, ***U.S.A.D.C.)
J Dent Res 1995, 74, 411

A 3 year clinical trial of a combination of trimetaphosphate and sodium fluoride in silica toothpastes
O’ Mullane DM*, Kavanagh D*, Ellwood RP*, Chesters RK, Schafer F, Huntington E, Jones PR (*Oral Health Research Centre, University College Cork, Ireland)
J Dent Res 1997, 76, 1776-1781

The relative efficacy of NaF silica toothpastes containing 1000ppm fluoride and 1500ppm fluoride in the control of dental caries is not clearcut. Also, lt has not been established that incorporation of trimetaphosphate (TMP) improves the anticaries activity of NaF toothpastes. A three-year clinical trial was conducted to test the hypotheses that: (i) the anticaries activity of NaF toothpastes containing 1500ppm F was greater than that of NaF toothpastes containing 1000ppm F, and (ii) lncluslon of TMP improved the efficacy of NaF silica pastes. Subsidiary aims included determination of whether frequency of toothbrushlng and method of rinsing after brushing were correlated with caries increments. The study involved 4196 children aged 11 to 12 years at outset. These participants had been selected from a pool of 7374 potential subjects on the basis of caries experience and dental eruption pattern. They were stratified by sex, examiner, and presence of calculus and caries, and were allocated at random to one of the four toothpastes under study. Using mirror and probe and also FOTI, we carried out clinical examinations at baseline and annually thereafter for 3yrs. Bitewing radiographs of a subset of children were taken at baseline and at the end of the study. The outcome measure for the study, DMFS increment, was defined as the increase in caries over 3yrs, taking into account changes occurring on individual tooth surfaces. Data for 3467 subjects were available for analyses at both baseline and year 3 examinations. Radiographs were taken for 1942 subjects at both baseline and year 3 examinations. The mean three-year cllnlcal-only DMFS increment for the subjects using 1500-ppm-NaF pastes was 3.93, which was 6% lower than the corresponding mean of 4.19 for the 1000ppm NaF pastes. There was no significant difference between the mean DMFS increment for those using paste with or without TMP. Subjects who claimed to brush more frequently or who claimed not to use a tumbler to rinse after toothbrushing had lower three-year DFMS increments.

Contribution of DMFS components to product discrimination
Jones PR, Chesters RK, Huntington E, O’Mullane DM*, Ellwood RP*, Kavanagh D* (*Oral Health Research Centre, University College Cork, Ireland)
J Dent Res 1997, 338

FOTI diagnosis of approximal caries in a 3 year clinical trial
O’Mullane DM*, Ellwood P*, Kavanagh D*, Jones PR, Chesters RK, Huntington E (*Oral Health Research Centre, University College Cork, Ireland)
Caries Res 1997, 31, 325

FOTI diagnosis of occlusal caries in a 3 year clinical trial
Ellwood RP*, Kavanagh D*, Jones PR, Chesters RK, Huntington E, O’Mullane DM* (*Oral Health Research Centre, University College Cork, Ireland)
Caries Res 1997, 31, 282

Contribution of FOTI to Product Discrimination
O’ Mullane DM*, Ellwood RP*, Kavanagh D*, Jones PR, Chesters RK, Huntington E (*Oral Health Research Centre, University College Cork, Ireland)
J Dent Res 1997, 76, 254

A caries susceptibility classification of tooth surfaces by survival time
Hannigan A*, O’Mullane DM**, Barry D, Schafer F and Roberts AJ (*University of Limerick, Ireland) (**University College Cork, Ireland)
Caries Res 34: (2) 103-108 Mar-Apr 2000

Individual tooth surfaces have vastly different susceptibilities to caries and this susceptibility also varies over time, The aim of this study was to develop a method of grouping tooth surfaces into a caries susceptibility classification based on their survival experience. The data used in the study were from a 3-year caries clinical trial. The definition of survival time was taken to be the time from the start of the trial to when a surface is recorded as decayed or filled. Cluster analysis was used to divide the tooth surfaces into groups in such a way that surfaces in the same group have similar survival time distributions. The 13 groups identified were ordered from 1 to 13 starting with the group with the shortest survival time, i.e. the occlusal surfaces of the four first molars. Approximately 80% of symmetrical pairs of tooth surfaces were in the same group. The groups obtained using cluster analysis were compared to groups defined using dental/anatomical criteria. It is concluded that the cluster analysis method developed for grouping the tooth surfaces cn provide a useful descriptive measure of caries susceptibility which can be applied to data from any longitudinal study of caries. Copyright (C) 2000 S. Karger AG, Basel.

The influence of toothbrushing frequency and post-brushing rinsing on caries experience in a caries clinical trial
Chestnutt IG*, Schäfer F, Jacobson APM** and Stephen KW** (*Lanarkshire Health Board, Department of Dental Public Health, Hamilton, Scotland) (**University of Glasgow Hospital and School, Glasgow, UK).
Community Dent Oral Epid 26: (6) 406-411 Dec 1998

Objective: To examine the effect of reported toothbrushing frequency and method of rinsing after brushing on caries experience and increment. Methods: Data are presented from 2621 adolescents (mean age 12.5 years at outset) participating in a 3-year doubleblind caries clinical trial. At baseline, examiners questioned each participant about their toothbrushing habits, and at subsequent examinations, this information was obtained using a self-administered computer-based questionnaire. participants used a fluoride-containing dentifrice throughout and clinical examinations were conducted using a mirror, CPITN probe and fibre-optic transillumination. Results: The reported brushing frequency increased throughout the trial. Caries experience at baseline was inversely related to toothbrushing frequency with mean DMFS=9.66, 8.12 and 7.63 respectively for <1/day 1/day and >1/day brushers (P<0.001). Mean 3-year DMFS increments of 8.90, 6.63 and 5.48 (P<0.01) were observed in those reporting to brush <1/day, 1/day or >1/day on not less than two of the three cli