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Biomedical subjects

M N Naylor

Publications and source records attributed to M N Naylor.

At least 19 recordsLinked to original sources
PubMed1997

A clinical trial of two fluoride dentifrices in an area of low caries prevalence.

OBJECTIVE: The study was designed to test the hypothesis that a dentifrice with fluoride at the same concentration (1000ppm) from two sources, ie NaF and NaMFP, would provide a greater treatment effect than one with NaMFP alone. BASIC RESEARCH DESIGN: A double blind clinical trial with random assignment of children to one of two groups was carried out for three years. The two trial groups were similar at the outset in respect to those variables which might otherwise have affected the outcome, including age and gender, with means per subject of 98.4 sound surfaces and 2.2 decayed and filled surfaces in each group initially. CLINICAL SETTING: Secondary schools in the Isle of Wight, UK, an area of diminished caries experience. PARTICIPANTS: One thousand six hundred and thirty-three children aged initially 10-12 years. INTERVENTIONS: A test dentifrice containing 500ppm NaF plus 500ppm NaMFP, and a standard active control product containing 1000ppm NaMFP. Products were used in the home. OUTCOME MEASURES: Increment of DF teeth and surfaces measured over 36 months. RESULTS: After three years, mean approximal surface increments were 3.6 new DFS in the control group and 3.1 in the test group, a difference 13 per cent (P < 0.05). Thirty-four per cent of the subjects were caries free at the outset. In the 1075 subjects with caries at the outset, the total mean increment on all surfaces was 7.2 new DFS in the control group and 6.4 new DFS in the test group, a difference of 11 per cent (P < 0.05). However, those subjects with initial caries had approximal surface increments of 4.8 new DFS in the control group and 4.0 new DFS in the test group, a difference of 16 per cent (P < 0.01). Included separately along with the conventional rubric were enamel white spots on which no differential treatment effect was observed. CONCLUSIONS: Under the conditions of this study, the regular use of a dentifrice containing 1000ppm fluoride from two sources provided a significantly greater treatment effect than one with fluoride from a single source.

Cariostatic Agents↗
PubMed1995

Initial caries attack and average progression rates in 12-year-old Isle of Wight children.

Initial caries attack and progression rates of posterior approximal carious lesions were assessed based on 12-year-old school children residing on the Isle of Wight. Bitewing radiographs of a sub-sample of 165 subjects were randomly selected from the control group of a dentifrice clinical trial which took place between 1984 and 1987. Of the approximal surfaces that were caries-free at the first examination 71 per cent of the same surfaces remained caries-free after three years, an overall initial caries attack rate averaging 10.7 per cent per annum. Of the mesial surfaces of first permanent molars, 455 were initially caries-free, 67 per cent of which remained so after a three year period. The attack rate of this specified surface was 12.4 per cent per annum. The majority of surfaces that were caries-free at the start of the investigation would therefore be expected to remain so at least three years later. Caries progression appeared to be a slow process with only 12 per cent of initially carious outer enamel surface lesions penetrating into dentine after one year. After two years this had increased to 46 per cent and after three years, to 62 per cent. For a similarly defined group of individuals it would appear likely that the majority of early enamel lesions would not reach dentine within two years. For a substantial number of subjects this would extend to at least three years.

Child↗
PubMed1992

Glycosidase activities in gingival crevicular fluid in subjects with adult periodontitis or gingivitis.

Specific glycosidase activities were determined in samples of gingival crevicular fluid (GCF) collected from eight predetermined sites in two groups, each of 20 adult patients, with either gingivitis or periodontitis. The total activities (as units of enzyme activity per sample) of alpha-L-fucosidase, sialidase, beta-N-acetylglucosaminidase, beta-galactosidase, beta-glucosidase and alpha-glucosidase were significantly greater in the periodontitis group. In contrast, the total beta-mannosidase and hexosaminidase A activities were significantly greater in the gingivitis group, while there was no significant difference in the total alpha-mannosidase activity between the groups. Only the specific activities (as units of enzyme activity per min per microliter of GCF) of beta-mannosidase and hexosaminidase A were significantly different between the groups being greater in the gingivitis group. When used to predict the clinical status of individual periodontal sites, the total enzyme activities had specificity and sensitivity values of 91.9 and 61.3%, respectively. Measurement of glycosidase activities might thus have a role in monitoring the efficacy of periodontal treatment or in predicting future periodontal disease but this will require further investigation.

Adult↗
PubMed1992

Inhibition of human subgingival plaque protease activity by chlorhexidine.

Subgingival plaque samples from three discrete sites in each of eight patients with adult chronic periodontitis were used to determine the ability of 0.001, 0.01, 0.1 and 1.0 mM chlorhexidine to inhibit bacterial proteolytic activity. This activity was measured by monitoring the increase in relative fluorescence (excitation and emission wavelengths of 495 and 525 nm, respectively) accompanying the degradation of fluorescein isothiocyanate (FITC)-labelled bovine serum albumin or FITC-labelled transferrin. Chlorhexidine at concentrations of as low as 0.01 mM inhibited the proteolytic degradation of both substrates by more than 50%. As the growth of dental plaque bacteria is dependent upon the liberation of nutrients (amino acids, peptides and carbohydrates) from host-derived macromolecules, similar effects in vivo might explain the ability of chlorhexidine to inhibit plaque formation at subminimal inhibitory concentrations.

Bacteria↗
PubMed1992

Prevalence of clinically undetected and untreated molar occlusal dentine caries in adolescents on the Isle of Wight.

The prevalence of clinically undetected occlusal dentine caries was determined in a group of adolescents living on the Isle of Wight by comparing data from clinical and radiographic examinations carried out in 1987. 6.3% of maxillary molars and 12.9% of mandibular molars which had been designated as clinically sound showed dentine caries on radiographs. Comparison of the radiographic data from 1975 and 1987 showed that there were more sound and fewer filled occlusal surfaces in 1987, but more primary occlusal caries. Approximately 50% of subjects examined in both 1975 and 1987 had at least one molar tooth with primary and/or secondary caries in dentine on radiograph.

Adolescent↗
PubMed1990

Protease activity in gingival crevicular fluid from discrete periodontal sites in humans with periodontitis or gingivitis.

Sensitive fluorogenic assays were used to compare the protease activities of fluid collected from eight such sites in each of 21 adult patients with gingivitis and 22 with periodontitis. The degradation of N-carbobenzoxy-gly-gly-arginine-AMC, L-arginine-AMC, glyproline-AMC, L-leucine-AMC, N-alpha-benzoyl-L-arginine-AMC, N-[p-toluenesulphonyl]-gly-pro-arginine-AMC, N-tert-butoxycarbonyl-leu-ser-thr-arginine-AMC, N-tert-butoxycarbonyl-ileu-glut-gly-arginine-AMC and N-tert-butoxycarbonyl-val-leu-lysine-AMC was significantly greater by fluid from the periodontitis group. The specific rates of degradation of L-arginine-AMC, gly-proline-AMC, N-alpha-benzoyl-L-arginine-AMC and N-[p-toluene-sulphonyl]gly-pro-arginine-AMC were significantly greater in that group, indicating that the composition of their gingival crevicular fluid was different from that of the gingivitis group. Discriminant analysis of the substrate hydrolysis data alone correctly identified 77.6% of sites with sensitivity and specificity values of 73.3 and 82.1%, respectively. The predictive value of these assays requires further investigation, but it is possible that they will prove useful for monitoring the success of periodontal treatment.

Adult↗
PubMed1982

The influence of the replacement of dietary sucrose by maltose on the formation and biochemistry of human dental plaque.

Samples of 2-day plaque were collected before and during two 25-day diet periods from 24 subjects taking part in a double-blind cross-over study involving sucrose- and maltose-rich diets. The mean change in plaque pH measured after exposure to the respective sugar during the 3rd week of both diet periods was similar. The dry weight of plaque did not vary significantly as either diet progressed but the lowest mean value obtained was in the 4th week of the maltose diet. The extracellular polysaccharide content of plaque was lower in the maltose group than in the sucrose group (p = 0.052). Plaque-invertase activity was not affected significantly by the diets but maltase activity was significantly higher in the 2nd and 4th weeks of the maltose diet (p = 0.039; p = 0.012). The results suggest that the polysaccharide matrix of plaque formed in the presence of maltose as opposed to sucrose is different, which could be explained by the known effect of maltose in vitro on plaque glucosyl transferases.

Adult↗