Biomedical subjects

K W Stephen

Publications and source records attributed to K W Stephen.

At least 19 recordsLinked to original sources

PubMed1996

Incremental susceptibility of individual tooth surfaces to dental caries in Scottish adolescents.

This study reports on the caries susceptibility of tooth surfaces in 4294 adolescents (mean age 12.5 yr) during a 3-yr, double-blind clinical caries trial, conducted in Lanarkshire, Scotland, between 1988 and 1992. Children were selected on the grounds of dental maturity and past caries experience. Clinical examinations with mirror, CPITN probe and fibre optic trans-illumination were carried out on the permanent dentition, with the buccal pits of mandibular molars and palatal pits of maxillary molars being recorded as separate sites. At baseline 6061 surfaces were decayed (1.0% of 601 160 surfaces examined), 20 160 (3.4%) filled, and 10 909 (1.8%) missing due to caries. The number of surfaces recorded as sound at baseline in subjects completing the study was 454 663. Of these 8176 (1.8%) new surfaces were decayed, 14 832 (3.3%) filled and 4000 (0.9%) missing at the final examination. Molar occlusal surfaces showed greatest susceptibility to attack, 35.8%) of those at risk becoming carious in the course of the study. All buccal and lingual smooth surfaces showed a low susceptibility, but 8.8% of buccal and palatal pits developed caries. At the final clinical-only examination, pit and fissure caries accounted for 48%, interproximal surfaces for 39%, and smooth surfaces for 13% of caries prevalence. However, overall the contribution of these surfaces to 3-yr increments was, 40%, 47% and 13%, respectively.

Adolescent↗

PubMed1996

The oral health status of Omani 12-year-olds--a national survey.

This study reports the first ever national oral health survey of Omani 12-year-olds. Conducted in October 1993, of the 3,435 children examined, 1,438 (41.9%) were caries-free, although regional variations ranged from 24.8% to 61.9%. Overall, the national DMFT averaged 1.53, the majority of caries experienced being in the form of untreated decay, with occlusal surfaces of first permanent molars being the most commonly involved site. Oral hygiene was poor, only 11% of those examined being scored as plaque-free.

Child↗

PubMed1996

Preparation and measurement of artificial enamel lesions, a four-laboratory ring test.

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 microns for IML. The IML of the lesions produced with the preferred protocol varied between 1,800 and 6,300 vol% mineral x microns. 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.

Analysis of Variance↗

PubMed1995

Dental fluorosis.

Explore the source record for details and available documents.

Adolescent↗

PubMed1995

Prevalence of clinically apparent recurrent caries in Scottish adolescents, and the influence of oral hygiene practices.

The prevalence of recurrent caries was recorded at the annual examinations of a 3-year double-blind caries clinical trial involving 4,294 children age 12-13 years at baseline. Recurrent caries was defined as clinically apparent disease affecting the restoration margins. Examination of all surfaces of undried teeth was carried out using a CPITN-C probe. The proportion of children with recurrent caries was 7.5, 9.5, 6.3 and 8.0% at baseline, year 1, year 2, and year 3. The proportions of restorations with recurrent caries was 1.9, 1.8, 1.0 and 1.1%, respectively, at each examination. A number of oral hygiene parameters were collected via a computer questionnaire. Water rinsing after brushing proved to be associated with recurrent caries (p < 0.01), those using a beaker having more recurrent caries than those using less diluting methods. Subjects who brushed twice a day (at the final examination) had less recurrent caries than those reporting to brush less often (p < 0.01). Both these results are consistent with previous findings on the association between DMFS increments and oral hygiene practices.

Adolescent↗

PubMed1995

Evaluation of the in vitro cariogenic potential of Streptococcus mutans strains isolated from 12-year-old children with differing caries experience.

The limited usefulness of caries activity tests based solely on counts of mutans streptococci has been recognised increasingly. Such tests do not account for potential differences in cariogenicity of Streptococcus mutans strains harboured by individual patients. Hence, this study describes the evaluation of a simple and inexpensive method involving the dissolution of powdered hydroxyapatite as a means of determining the cariogenic potential of 64 freshly isolated strains of S. mutans from 24 children. Whilst it is apparent that differences between strains isolated from individuals could be demonstrated using this test, the variability observed was such that it was not possible to relate in vitro cariogenicity to actual clinical caries experience.

Anions↗

PubMed1995

The site-specificity of supragingival calculus deposition on the lingual surfaces of the six permanent lower anterior teeth in humans and the effects of age, sex, gum-chewing habits, and the time since the last prophylaxis on calculus scores.

The hypotheses to be tested were: (i) that chewing sugar-free gum frequently and for long periods would be associated with higher amounts of supragingival calculus, and (ii) that there would be no site-specificity of calculus deposition on the lingual surfaces of the 6 lower anterior teeth. Subjects, 436 in Glasgow and 191 in Winnipeg, were scored for calculus at mesial, lingual, and distal sites on the lingual surface of each of the 6 lower anterior teeth, by the Volpe-Manhold method. They also answered questions on the time since the last prophylaxis, the frequency of gum chewing, the type of gum chewed, and the length of a typical gum-chewing episode. A subset (233) of the Glasgow subjects were scaled and re-scored for calculus 3 months later. When the data for the logarithmic transformations of the initial calculus scores were subjected to stepwise multiple-regression analysis, the only factor which correlated significantly with initial calculus scores in both cities was the time since the last prophylaxis. In the Glasgow subjects scored 3 months after a prophylaxis, there was a negative correlation between chewing sugar-free gum and calculus scores, whereas in the Winnipeg subjects, age and the chewing of sucrose-containing and sugar-free gum were positively correlated with calculus scores. Thus, the results were contradictory with respect to the first-tested hypothesis. The calculus distribution patterns were very similar in the subset of Glasgow subjects and the Winnipeg subjects, with the amounts on the lateral incisors and canines averaging 70.2% and 44.5%, respectively, of those on the central incisors. Thus, the second hypothesis was disproved.

Adolescent↗

PubMed1995

The value of anti-caries and anti-plaque dentifrices at a community level.

Although dentifrices (in a modern sense) were first introduced at the turn of the century, it was not until the advent of fluoride-containing compounds that any of therapeutic value was produced. In the early post-war years, formulation compatibility difficulties occurred, with the result that none was demonstrated to have clinically proven efficacy until stannous fluoride was successfully incorporated in the "Crest" formulation of 1955. Thereafter, sodium monofluorophosphate (SMFP) appeared, to be followed by organic and acid-phosphate fluoride preparations, most of which were shown to produce clinical benefit over placebo controls. Since the late 1970's, however, such studies have been deemed unethical in many countries in view of the almost universal availability of efficacious fluoride dentifrices. While an NaF formulation was the first to be tested (albeit unsuccessfully) by Bibby (1945), there was a considerable time period before the arrival of both stable and effective silica-based systems in the early 1980's. Results of studies have varied, but the largest ever double-blind NaF/SMFP head-to-head dentifrice trial yet published (Stephen et al., 1994) has indicated a 6.4% significant benefit in favor of NaF (in silica) over SMFP. With respect to the effect of dentifrice fluoride levels, above 1000 ppm dose-response caries reductions have been obtained, but the efficacy of preparations containing 500 ppm F or less has yet to be demonstrated. In relation to root caries, Jensen and Kohout (1988) reported a 41.4% DFS significant reduction in subjects who used a NaF/silica dentifrice at 1100 ppm F, over a one-year period.

Clinical Trials as Topic↗

PubMed1995

The effect of social and personal factors on the utilisation of dental services in Glasgow, Scotland.

This study examined potential mediators of dental attendance among two distinct adult populations who lived in contrasting social environments (deprived and affluent). The aim of the study was to describe and quantify the effect of both the potentially modifiable and the fixed factors which influence use of dental services. A two-stage weighted random sampling technique was used to select 863 participants who were interviewed. Of these participants, 372 lived in 'affluent' areas and 491 in 'deprived' areas. The 45 minute interview explored many aspects of oral health, and related behaviour and attitudes. The results showed a highly significant association between social deprivation and reported dental attendance (P < 0.001). Social environment was also significantly related to asymptomatic dental attendance. Deprived respondents' dental behaviours were significantly affected by life events and yet structural/organisational barriers to attendance had a significantly greater impact on the affluent population's dental visiting patterns than they did on the deprived population's. A regression model indicated that the best predictors of dental attendance were social environment, dental anxiety, perceptions about denture wearers and the value placed upon restored teeth. The study suggests that the barriers to dental attendance experienced by deprived populations are not easily modifiable, but belong instead to a group which relate to the socio-political agenda. The study also demonstrates the importance of accurate and regularly updated community registers for use in population based health services research.

Adolescent↗

PubMed1994

The prevalence and effectiveness of fissure sealants in Scottish adolescents.

The presence of fissure sealants was recorded in 4294 adolescents during a 3-year, double-blind clinical caries trial, conducted in Lanarkshire, Scotland, between 1988 and 1992. Of 68,704 occlusal surfaces examined at baseline, sealants were detected on 7011 (10.2%) surfaces, in 1596 subjects. Of these, 17.4% were judged as incompletely sealed. At the final examination 24.3% of sealants originally recorded as complete were missing, with partial loss observed on a further 18.2% of surfaces. At that time, 21.4% of surfaces 'unsealed but sound' at baseline were recorded as decayed, filled or extracted due to caries, compared with 14.4% of surfaces on which an intact sealant had been recorded (P < 0.001). In contrast, of those surfaces on which the sealant was noted as deficient at the outset, 22.9% were judged to have been affected by caries. This study shows that sealants should be repaired when deficient if they are to be effective.

Adolescent↗

PubMed1994

An in vitro investigation of the cariogenic potential of oral streptococci.

Whilst the importance of the mutans streptococci in the aetiology of dental caries is clear, a number of studies have described caries development in their absence. This investigation aimed to assess the cariogenic potential of Streptococcus gordonii, Strep. sanguis, Strep. vestibularis and Enterococcus faecalis in comparison with Strep. mutans and Strep. sobrinus, using a recently described in vitro model. In the presence of a 146 mM sucrose solution and powdered hydroxyapatite, each species was incubated for 5 h, after which acid anion production, calcium release and change in pH were measured. It was possible to assign each species to one of three groups, with E. faecalis, Strep. gordonii, Strep. sanguis exhibiting low, Strep. vestibularis intermediate, and Strep. mutans and Strep. sobrinus high in vitro cariogenic potential. This assay could be used as a screening test to assess the potential cariogenicity of a range of bacterial species.

Acetates↗

PubMed1994

Demonstration of a fluoride dose response with an in situ single-section dental caries model.

The in situ dental caries model developed in Glasgow was evaluated by determining whether it could demonstrate a fluoride dose response in a crossover study using 0, 250, and 1,000 ppm F from sodium fluoride dentifrices. In situ appliances, each carrying four enamel sections with multiple artificial carious lesions, were worn by 12 dentate subjects for three 5-week experimental runs, during which they brushed twice daily with a test paste. Mineral changes in the lesions were measured by analyzing microradiographs, using an image analysis system, after 0, 2, 4, and 5 weeks and the rate of change calculated. Two-way analysis of variance showed no significant intersubject effects (for any of the parameters), but demonstrated strong evidence of a linear fluoride dose effect: total mineral loss (delta z) p = 0.0596; lesion body p = 0.0423; surface zone p = 0.0081. However, the exclusion of the data from 1 low-caries (DMFS = 1), high-calculus-forming subject produced even stronger evidence as to the efficacy of this model (delta z p = 0.0226; lesion body p = 0.0164; surface zone p = 0.0081). Hence, these results suggest this model is useful for studying fluoride products according to guidelines of American Dental Association.

Adult↗

PubMed1994

Fluoride toothpastes, rinses, and tablets.

Only from the mid-1950's has therapeutic benefit been obtained via dentifrices, initially with stannous fluoride-then monofluorophosphate-containing products which remained stable and efficacious. Altered abrasive systems followed, and both sodium fluoride and monofluorophosphate/sodium fluoride mixtures were introduced as active anti-caries agents, with recent meta-analysis indicating that sodium fluoride > monofluorophosphate/sodium fluoride > monofluorophosphate. With respect to fluoride levels, clear dose-response relationships have been demonstrated. However, at < 1000 ppm F, the situation is less certain. Since the mid-1980's, anticalculus fluoride dentifrices have been marketed, and have been shown to have similar caries-reducing potential as their non-calculus-inhibiting control formulae. Finally, one study has been described where a sodium fluoride dentifrice successfully reduced root caries. Of the many fluoride formulations used for caries-inhibiting mouthrinsing [e.g., acid phosphate fluoride (100-3000 ppm F), sodium fluoride (45-3000 ppm F), stannous fluoride (100-250 ppm F), ammonium fluoride (1000 ppm F), and amine fluoride (250 ppm F)], sodium fluoride would seem to be the preferred agent. Furthermore, rinse frequency is deemed more important than fluoride ion concentration, but caution is urged re the volumes and concentrations to be used by children, no rinsing being recommended below 4 years. Combination of a 440-pp-F sodium fluoride and 0.05% chlorhexidine school-administered rinse appears to have increased the caries-inhibiting benefit as compared with sodium fluoride alone. Fluoride supplements have reduced deciduous caries from 14 to 93%, and in the permanent dentition, from 20 to 81%.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluorides↗

PubMed1994

The effect of NaF and SMFP toothpastes on three-year caries increments in adolescents.

A three-year double blind clinical caries trial was undertaken to compare the anticaries efficacy of three types of active agent, namely sodium fluoride (NaF), sodium monofluorophosphate (SMFP) and the combination of NaF plus sodium trimetaphosphate (TMP), using two fluoride levels (1000 ppm F and 1500 ppm F). The prime objective of the study was to determine whether there was any difference in the anticaries efficacy between NaF and SMFP. The second objective was to assess the effect on caries protection of the incorporation of TMP into a NaF dentifrice formulation. The study was carried out to FDI protocol and involved 4,294 children aged 11-12 years at outset. These participants had been selected from a pool of 6,212 potential subjects on the basis of caries experience and dental eruption pattern. They were stratified by sex, examiner, presence of calculus and caries, and allocated at random to one of the six toothpastes under study. Clinical examinations were carried out at baseline and thereafter annually for 3 years. 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 three years, taking into account changes occurring on individual tooth surfaces. After three years, clinical-only data for 3,517 children were available for the calculation of caries indices. The mean three-year DMFS increment for subjects using a dentifrice containing NaF alone was 6.4 per cent lower than for those using a dentifrice containing SMFP. The difference between the NaF+TMP users and the SMFP users was 8.1 percent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

A critical review of the relative anticaries efficacy of sodium fluoride and sodium monofluorophosphate dentifrices.

While there is broad consensus in the research community that fluoride dentifrices provide important anticaries benefits, debate still remains as to the most efficient form of fluoride used in toothpastes. Recently, the authors of this paper collaborated as part of a scientific advisory group whose objective was to comprehensively review all clinical information available comparing the anticaries efficacy of the two agents most widely used in fluoridated toothpastes, sodium fluoride (NaF) and sodium monofluorophosphate (SMFP). This review included a detailed analysis of each published study pertinent to the question, a comprehensive meta-analysis of all available clinical findings, and an epidemiological assessment of how anticaries benefits of dentifrices may be anticipated to propagate with time. Overall, the use of meta-analysis of head-to-head clinical comparisons between the two fluoride-active systems was found to be the most valid means for comparing the relative efficacy of NaF and SMFP dentifrices. Results of this analysis demonstrated that NaF was significantly more effective than SMFP in preventing caries (p < 0.01). While the numerical difference in efficacy between NaF and SMFP measured between 5 and 10% (total DMFS) over a 2- to 3-year clinical period, this could be expected, on theoretical grounds, to propagate to substantially larger differences (e.g. 10-20%) over 10-20 years. Hence, the difference in efficacy between these two actives was judged to be clinically important as well as statistically significant. Based upon these findings the authors recommend that NaF be used as the active system in fluoridated dentifrices whenever practically feasible. However, the authors caution that this recommendation pertains to the formulation of NaF in highly compatible abrasive systems, which must be demonstrated by critical evaluation of ionic fluoride within formulations for stability, availability and bioavailability. One additional recommendation emanating from this review is that important improvements must be made in the design, execution and reporting of future caries clinical trials in order to bring these important methods up to scientifically acceptable standards.

Adolescent↗

PubMed1993

Systemic fluorides: drops and tablets.

Fluoride drops and tablets are effective caries-inhibiting agents which exercise their benefit through mainly topical means. Results of caries trials in which drops or tablets were used in the home vary from excellent to poor, depending on the compliance rates of both parents and offspring. Delivery in schools has also produced reductions of > 80%, and as poor as 20%, again possibly dependent on teacher vigilance. The pre-natal controversy re fluoride tablet benefits has only recently been tested under a true double-blind protocol and resulted in a non-significant effect, although the trend was in favour of those whose mothers had taken F- tablets during pregnancy. Hence, while at the individual level, the slow intra-oral dissolution of fluoride tablets can be of great benefit for coronal caries in children, adolescents, and possibly medically compromised adults (with or without root caries), their contribution on a community basis cannot readily be compared with that of water or salt fluoridation. Although fluoride tablets have been held responsible for an increase in fluorosis prevalence, data which were assessed blind now exist to show that a daily dosage of 0.25 mg fluoride from birth is not associated with dental fluorosis, if additional fluoride products are not used injudiciously over the same period.

Administration, Oral↗

PubMed1993

Dentifrices: recent clinical findings and implications for use.

Since fluoride dentifrices first became available over 30 years ago many formulation changes regarding fluoride type, concentration and abrasive systems have occurred to improve stability, compatibility, and also bioavailability of active ingredients. As a result, it is now established that from 1000-2800 ppm F, there is a dose-response relationship. However, at fluoride levels below 1000 ppm, efficacy has yet to be established fully. In the recent past, meta-analytic techniques employed on data concerning > 14,000 clinical trial subjects from 12 studies, have established that the use of NaF in a correctly formulated silica base provides superior caries protection than does either an NaF + SMFP, or SMFP dentifrice. Furthermore, the incorporation of anti-calculus and anti-microbial agents into fluoride dentifrices has not been shown to have any effect--either beneficial or adverse--on caries levels. Investigations designed to optimise the benefit obtained from fluoride-containing toothpastes, have demonstrated that toothbrushing frequency and post-brushing oral rinsing habits can significantly affect caries levels, as assessed over a 3-year period. However, as dentifrice ingestion by young children is now an established fact, care must be exercised when advising parents regarding fluoridated dentifrice usage as part of a prevention regime for children under 6-7 years of age. Nonetheless, while there would appear to be a dentifrice-related fluorosis problem in North America, such evidence as currently exists within the UK, does not indicate that the level of symmetrical mottling currently observed (< 6 per cent in > 8,500 12-14-year-olds) constitutes any public health problem.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Caries↗

PubMed1992

Assessment of the cariogenic potential of Streptococcus mutans strains and its relationship to in vivo caries experience.

Strains of Streptococcus mutans isolated from the plaque of 6 subjects were studied using an in vitro model to determine whether differences in their cariogenic potential could be detected, and if so, whether the results correlated with the caries experience of the individuals. Each strain was incubated with a bovine enamel slab and 5% (w/v) sucrose for 24-h periods. The acidogenic potential was assessed by pH measurement and analysis of acid anion production. Microradiographic and microdensitometric assessment of the enamel, together with measurement of the change in calcium concentration of the reaction mixture were used to determine the demineralizing potential of each strain. Significant differences in cariogenic potential were found between some of the strains tested, and correlations were found between 3 of the test parameters and the decayed-missing-filled-surface score of the individuals. The results suggest that the caries experience of individuals may be related, to some extent, to the cariogenic potential of their S. mutans strains.

Acetates↗