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Biomedical subjects

W Peter Holbrook

Publications and source records attributed to W Peter Holbrook.

16 recordsLinked to original sources
PubMed2006

Antimicrobial activity of monocaprin: a monoglyceride with potential use as a denture disinfectant.

Monocaprin is a 1-monoglyceride of capric acid that has antimicrobial activity against enveloped viruses, certain bacteria, and the yeast Candida albicans. Solutions containing monocaprin were formulated and tested in vitro against a number of micro-organisms, including species found in the oral cavity and common pathogenic species. The antimicrobial activity of monocaprin was tested with strains growing on a surface as well as in the planktonic phase. Micro-organisms tested were: Streptococcus mutans, Candida albicans, Lactobacillus sp., Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Two sets of dilutions were prepared for each test strain; one to be inoculated with the micro-organism growing in the planktonic phase and the other with the same strain growing on a filter paper disk. Control solutions were also prepared to find out if any of the excipients were affecting the microbicidal effect of monocaprin. Test strains growing on the filter paper surface were less sensitive to monocaprin than the same strain growing in its planktonic phase. C. albicans was the micro-organism that was most sensitive to monocaprin, but S. mutans also showed appreciable sensitivity. The indication that monocaprin may have potential as a topical agent against Candida was tested in an open study of denture disinfection in 32 patients attending a geriatric daycare centre. A significant, but short-term, reduction in counts of Candida on the fitting surface of full dentures was observed.

Aged↗
PubMed2005

Properties of hemagglutination by Prevotella melaninogenica.

Although Prevotella melaninogenica belongs to the commensal oral microbiota, some strains possess putative virulence factors. For example, we have previously described fimbriated, hemagglutinating strains of P. melaninogenica, isolated from patients with periodontal disease. The aim of this investigation was to compare some chemical and physical properties of hemagglutination (HA) of P. melaninogenica with those of other pigmented gram-negative anaerobes. HA of 13 P. melaninogenica strains proved to be considerably weaker than that of the major periodontal pathogen, Porphyromonas gingivalis. Vigorous shaking reduced HA of shaken cells but the shaken supernatant had the same hemagglutinating activity as non-shaken cells. The hemagglutinating agent on P. melaninogenica seemed to be a protein, which can be separated from the cell and binds to lactose-, galactose-, and raffinose-containing carbohydrates on the erythrocytes. Adherence to epithelial cells did not differ significantly between the hemagglutinating and non-hemagglutinating strains of P. melaninogenica. Although P. melaninogenica is able to agglutinate erythrocytes, this potential virulence factor is of a considerably lower magnitude than that of major periodontal pathogens.

Journal Article↗
PubMed2004

Consistency of DIAGNOdent instruments for clinical assessment of fissure caries.

DIAGNOdent (KaVo, Biberach, Germany) has shown high diagnostic accuracy and intra-operator agreement for caries detection, both in vitro and in vivo. The aims of this study were to compare DIAGNOdent with visual examination (VI) and bitewing radiographs (BW) for clinical assessment of occlusal fissures, and to evaluate inter-device consistency of clinical recording using four different DIAGNOdent instruments; secondly, to correlate DIAGNOdent readings with microbial culture of the measured site. The subjects were young adults, the material comprising 34 occlusal fissures, scheduled for restorative treatment at the Dental School Clinic of the University of Iceland. Two examiners conducted visual and radiographic assessments. One examiner measured each site with four DIAGNOdent instruments in random order. The fissure was then opened and lesion depth was classified on a 4-point scale. Bacterial samples were taken from the fissure before and after opening. Intra-operator agreement was high (r = 0.85-0.98). Inter-device correlation for the four DIAGNOdent instruments was significant in all cases (r = 0.81-0.92). However, a common cut-off point could not be determined. There was weak but significant correlation between DIAGNOdent readings and all three classes of lesion depth. Level of infection showed very weak correlation with the DIAGNOdent readings. It was concluded that DIAGNOdent is more reliable in detecting dentinal caries if a proper cut-off point is used than in indicating actual lesion depth. Readings from the different instruments were not directly comparable, however, owing to the lack of a common cut-off point.

Adolescent↗
PubMed2004

Clonal similarity of salivary and nasopharyngeal Fusobacterium nucleatum in infants with acute otitis media experience.

The environment of an infant's nasopharynx during acute otitis media (AOM) favours the growth of anaerobic bacteria, which can be recovered frequently during infection, but hardly at all if the infant is healthy. The aim of this investigation was to identify the potential source and inoculation route of anaerobes that were present in the nasopharynx. Eleven Fusobacterium nucleatum isolates that were collected through the nasal cavity from the nasopharynx of eight infants with a history of AOM, and 161 F. nucleatum isolates from the saliva of the same infants, were typed to the clonal level by using arbitrarily primed PCR (AP-PCR). In five of the eight infants examined, identical AP-PCR types were found among nasopharyngeal and salivary isolates. As anaerobes seem to be present only transiently in the nasopharynx and salivary contamination of the nasopharyngeal samples can be excluded, this observation indicates that the source of nasopharyngeal anaerobes is the oral cavity and that saliva is their transmission vehicle.

Acute Disease↗
PubMed2004

Parental perception of fluorosis among 8-year-old children living in three communities in Iceland, Ireland and England.

OBJECTIVES: To assess the impact of enamel fluorosis in three of the communities examined in 'Project FLINT', it was decided to conduct a structured telephone interview with the parents of some of the children who took part in the study. METHODS: Three communities involved in this project were able to conduct this investigation: Reykjavik (Iceland), Cork (Ireland) and Knowsley (England). The aim was to interview the parents of children with a range of Thylstrup and Fejerskov (TF) index grades selected from each participating centre with respect to the appearance of their child's permanent maxillary central incisors. Interviewers were blinded as to the TF grade of the subject. RESULTS: Interviews were conducted with parents of 215 children: 69 with TF grade 0; 70 with TF grade 1; 60 with TF grade 2 and 16 with TF grade 3 or greater. There was a trend towards more parents being unhappy with the appearance of their child's teeth with increasing TF grade. However, the main reasons given by parents for being unhappy with the appearance of their child's teeth was tooth alignment followed by the more yellow colour of permanent compared with primary teeth. Only with a TF grade of 3 was any appreciable concern expressed about fluorosis. CONCLUSION: It would appear that there is a public awareness of both developmental defects and enamel fluorosis although this is not always expressed as dissatisfaction. Further research is required into the clinical impact of both fluorosis and other developmental defects of enamel.

Child↗
PubMed2004

Development of a standardized method for comparing fluoride ingested from toothpaste by 1.5-3.5-year-old children in seven European countries. Part 1: Field work.

OBJECTIVES: To develop a standardized method for measuring the variables affecting fluoride ingestion from toothpaste in young children between the ages of 1.5 and 3.5 years, and to use the method at seven European sites. METHODS: Random samples of children were invited to take part in the study. Parents who gave consent were visited at home. The children brushed their teeth using the toothpaste brand and toothbrush type currently in use. Variables measured were: type of toothpaste used, fluoride concentration of toothpaste used, weight of toothpaste used, frequency of brushing and body weight of the child. RESULTS: It was not possible to follow the agreed protocol in all seven countries and in three countries appropriate alternative methods were employed. There was considerable variation between countries in the variables investigated. Use of children's toothpaste ranged from 69% in Ireland to 98% in Portugal. In the Netherlands up to 60% of the children were using toothpaste containing <400 ppm F and in Finland up to 27% of children were using toothpaste containing >1200 ppm F. Over half of the children used <0.25 g of toothpaste per brushing and the majority of children brushed once or twice per day. CONCLUSION: Although adherence to the agreed protocol was not possible at all study sites there was a clear picture of considerable variation in the oral hygiene practices of young children throughout Europe.

Analysis of Variance↗
PubMed2004

Development of a standardized method for comparing fluoride ingested from toothpaste by 1.5-3.5-year-old children in seven European countries. Part 2: Ingestion results.

OBJECTIVES: To develop a standardized method for measuring the variables affecting fluoride ingestion from toothpaste in young children between the ages of 1.5 and 3.5 years, and to use the method at seven European sites. METHODS: Random samples of children were invited to take part in the study. Parents who gave consent were visited at home. The children brushed their teeth using the toothpaste brand and toothbrush type currently in use. The difference between the fluoride dispensed onto the toothbrush and the fluoride recovered after accounting for losses was deemed to be the fluoride ingested. Details of other oral health-care habits were collected by questionnaire. For each child, the fluoride concentration of the toothpaste used was measured in the laboratory, from which an estimate of total daily fluoride ingestion was made. RESULTS: There was considerable variation between countries in the types of toothpaste used and in the amounts of toothpaste applied and ingested. The amount of fluoride ingested ranged from 0.01 to 0.04 mg fluoride per kg of body weight per day. CONCLUSION: The amount of fluoride ingested that is likely to be a risk factor for the development of dental fluorosis during tooth formation is equivocal and was found to vary widely between European countries. There appears to be a need for clearer health messages regarding the use of fluoridated toothpaste by young children.

Analysis of Variance↗
PubMed2004

Urinary fluoride excretion by preschool children in six European countries.

OBJECTIVE: To measure and compare 24-h urinary fluoride excretion in children aged 1.5-3.5 years from European study sites and to use these data to estimate the 24-h fluoride intake. METHOD: Twenty-four-hour urine samples were collected from 3-year-old children (n = 86) who were already participating in a European multicentre study. Samples were collected from Cork, Ireland (n = 19) where the water is fluoridated to a concentration between 0.8 and 1.0 ppm and from five sites with a water fluoride concentration <0.15 ppm: Knowsley, England (n = 18); Oulu, Finland (n = 18); Reykjavik, Iceland (n = 4); Haarlem, the Netherlands (n = 6); Almada/Setubal, Portugal (n = 21). The volume of the samples was measured; they were analysed for fluoride concentration and the 24-h urinary fluoride excretion was calculated. From this an estimate of the daily fluoride intake was made. RESULTS: It was found that the mean fluoride excretion in response to the usual conditions of fluoride intake in the children in the nonfluoridated areas ranged from 0.16 mg (+/-0.08) in Oulu to 0.33 mg (+/-0.27) in Almada/Setubal with an overall mean of 0.23 mg (+/-0.19). The mean 24-h fluoride excretion in fluoridated Cork was 0.37 mg (+/-0.11). There was a significant difference between the fluoride excretion in the nonfluoridated areas and that in the fluoridated areas, and the data were broadly in agreement with WHO standards. CONCLUSIONS: The daily urinary fluoride excretion and estimated fluoride intake in these children appeared to be within acceptable limits.

Cariostatic Agents↗
PubMed2004

A European perspective on fluoride use in seven countries.

OBJECTIVES: The aim of this study was to collate data on national policies for the use of fluoride in the seven European countries participating in the FLINT project. METHODS: Policies on the use of fluoride were obtained for each of the study areas. Data collected included the presence of water fluoridation and regulations governing fluoride toothpaste and fluoride supplements. RESULTS: In Ireland 74% of the population had a fluoridated water supply but in all the other countries fluoride toothpaste was the principal form of delivering fluoride, usually recommended as a dose of a pea-sized amount. Fluoride supplement use varied considerably between countries. The Netherlands had the clearest regulations covering the use of fluoride supplements and definition of at-risk individuals. Most countries, even if they recognized particular caries-risk did not define the term clearly. In Iceland all children were regarded as being at high risk of developing caries. CONCLUSION: Considerable variation exists between European countries in their policies for fluoride use and no clear definitions of high-caries-risk individuals were found. The results show that there is even a lack of coherent thought and planning within the different countries, let alone between them.

Cariostatic Agents↗
PubMed2004

Fluoride ingestion from toothpaste: conclusions of European Union-funded multicentre project.

An important challenge encountered in this multicentred project was the need to take account of the different cultural and legal differences between the seven sites when agreeing the protocol. Examples such as access to registers of births and subject consent dictated that there were some differences in the methods used in the different sites. The data presented showed that it was possible to train and calibrate a number of examiners in a standardized photographic method for recording enamel fluorosis. This method has a number of important advantages for the objective monitoring of enamel fluorosis over time. There were considerable differences between the seven sites in the formulations of the toothpaste used and in the pattern of their use. The results indicate that it is possible to agree and adopt a standardized method for measuring fluoride ingestion from toothpaste. The aesthetic impact of enamel fluorosis seemed low in the populations included in this project, but further work is required on this issue.

Cariostatic Agents↗
PubMed2003

Prevention. Part 3: prevention of tooth wear.

Non-carious destruction of teeth has been observed in archaeological material from various parts of the world and clearly pre-dates the first appearance of dental caries. Attrition, abrasion and erosion are also described in the classic text of Pindborg on the pathology of the dental hard tissues. Whilst the dental profession, at least in affluent parts of the world, was engaged in diagnosing, treating and later preventing dental caries these other causes of tooth destruction were largely ignored.

Humans↗
PubMed2003

Dental erosion in Icelandic teenagers in relation to dietary and lifestyle factors.

High consumption of fruit juices and carbonated drinks has been related to dental erosion. Teenage male Icelanders consume about 800 ml of carbonated drinks per day on average and this corresponds with the main age group and gender of patients seen with erosion. This study examined the prevalence of dental erosion in 15-year-old children in Reykjavík and looked at the association between erosion and some lifestyle factors in a case-control study drawn from the same sample. A 20% sample of the 15-year-cohort population (n = 278) was selected. Dental erosion was classified by location and severity (1 = enamel erosion; 2 = dentine erosion; 3 = severe dentine erosion) and was seen in 21.6% of subjects (68.3% male; 72% scored as grade 1; 23% grade 2; 5% grade 3). Control subjects were the first healthy subjects examined after a case subject had beens diagnosed. In the case-control study, information was gathered by multiple-choice questionnaire on symptoms of gastric reflux, tooth sensitivity, some lifestyle and dietar-factors. Several lifestyle and dietary factors, previously shown to be significantly related to dental caries in Icelandic teenagers, showed no significant relationship to tooth erosion. Although dietary factors are probably important in causing erosion, dietary recall questionnaires did not help in discovering individuals likely to develop erosion.

Adolescent↗
PubMed2002

Oral lichen planus has a high rate of TP53 mutations. A study of oral mucosa in icelanD.

Oral squamous cell carcinoma (OSCC) is a world-wide health problem. In addition to external exposure (smoking and alcohol), certain oral lesions may increase the risk of oral cancer (e.g. leukoplakia, erythroplakia, and oral lichen planus). TP53 has been implicated in OSCC, but there are limited studies of mutations in premalignant oral lesions. In this study, 55 samples from OSCC, 47 from hyperkeratotic (HK) oral mucosa, clinically diagnosed as white patches, 48 samples from oral lichen planus (OLP), and 12 biopsies from normal oral mucosa were studied immunohistochemically for expression of TP53 protein. From all the carcinoma samples and selected non-malignant samples showing moderate or strong TP53 protein expression, malignant cells or TP53-positive nuclei were microdissected and screened for mutations in exons 5-8 by constant denaturation gel electrophoresis. Moderate to strong TP53 protein staining was seen in 56% of OSCC, 32% of OLP but only in 13% of HK. All OLP samples showed a characteristic pattern of positive nuclei confined to the basal layer, whereas TP53 staining was seen in suprabasal nuclei in HK. Mutation rate was 11 out of 52 for OSCC, three out of 20 tested for HK and, remarkably, nine out 27 tested for OLP. There was no correlation between TP53 protein staining and TP53 mutations. No associations were found with anatomical sites or disease progression. The unexpectedly high mutation rate of OLP might explain the premalignant potential of this lesion.

Adult↗
PubMedDate not supplied

[Erosive drinks on the icelandic market.].

OBJECTIVE: Dental erosion seems to be a growing health problem in Iceland. The international literature indicates that beverages such as carbonated drinks and fruit juices have considerable potential to causes tooth erosion. The aim of this study was to assess the erosive potential of drinks on the Icelandic market. MATERIALS AND METHOD: This study measured, on three occasions: (1) pH before titration and (2) the volume of 1.0M sodium hydroxide required to raise the pH of 50 ml of the beverages to pH 5.5, pH 7.0 and pH 10.0. RESULTS: The pH before titration ranged from pH 2.03-6.79 and the volume of 0.1M sodium hydroxide required to bring the beverages to pH 5.5 ranged from 0.54 to 5.92ml, pH 7.0 ranged from 0.42 to 7.73ml and pH 10.0 ranged from 2.23 to 9.10ml. This study showed that citrus fruit juices (grapefruit and orange juice) needed the most base to neutralize of the beverages tested. The milk-based beverages had an initial pH above 5.5 and are therefore non-erosive, with the exception of milk-derived lactic acid and drinks containing lactic acid aimed especially at the child market. Carbonated drinks, sport drinks and energy drinks were relatively easy to neutralize despite having a lower pH than fruit drinks. CONCLUSIONS: It is concluded that many soft drinks have considerable erosive potential and several of these are particularly targeted at the age groups found in other Icelandic studies to consume large amounts of soft drinks and to have tooth erosion.

English Abstract↗