A moderated mediation analysis on the influence of social support and cognitive flexibility in predicting mental wellbeing in elite sport

The purpose of this study was to examine the mechanism by which social support influences mental wellbeing. Using the thriving through relationships model to provide a theoretical underpinning, cognitive flexibility was hypothesised as a mediator. Additionally, the research examined the consistency of this pathway between elite athletes, retired athletes, and non-athletes. Survey responses from a sample of 247 participants (n = 49 elite athletes, n = 61 retired athletes, n = 137 convenience sample; of which 127 (51.4%) were males were included in the analysis. Initial mediation analysis revealed a significant indirect pathway from social support to mental wellbeing through cognitive flexibility. Moderated mediation analysis revealed this pathway was significant for retired athletes and the convenience sample, but not for elite athletes. Results provide additional insight into the mechanisms by which social support influences wellbeing. Cognitive flexibility interventions may not be as effective for elite athletes.

Embracing neurodiversity in doll play: Investigating neural and language correlates of doll play in a neurodiverse sample

Doll play may provide opportunities for children to rehearse social interactions, even when playing alone. Previous research has found that the posterior superior temporal sulcus (pSTS) was more engaged when children played with dolls alone, compared to playing with tablet games alone. Children's use of internal state language (ISL) about others was also associated with pSTS activity. As differences in social cognition are frequently observed in autistic people, we were interested in the brain and language correlates of doll play in children with varying levels of autistic traits. We investigated children's (N = 57, mean age = 6.72, SD = 1.53) use of ISL and their pSTS brain activity using functional near-infrared spectroscopy (fNIRS) as they played with dolls and tablet games, both alone and with a social partner. We also investigated whether there were any effects of autistic traits using the parent-report Autism Spectrum Quotient-Children's Version (AQ-Child). We found that the left pSTS was engaged more as children played with dolls or a tablet with a partner, and when playing with dolls alone, compared to when playing with a tablet alone. Relations between language and neural correlates of social processing were distinct based on the degree of autistic traits. For children with fewer autistic traits, greater pSTS activity was associated with using ISL about others. For children with more autistic traits, greater pSTS activity was associated with experimenter talk during solo play. These divergent pathways highlight the importance of embracing neurodiversity in children's play patterns to best support their development through play.

Factors that affect fractured neck of femur outcome: Clinical commissioning groups influence length of stay and discharge destination

BACKGROUND

The average length of stay (LOS) following a hip fracture in hospitals around the UK has been approximately 20 days in recent years. This can vary between hospitals and there are numerous factors that can affect LOS. We had the impression that LOS varied by Clinical Commissioning Group (CCG) from which the patient originates. The aim of our study was to discover whether the concern was valid, and if so, what the reasons may be.

METHODS

We analysed hip fracture data collected at our Trust between September 2008 and December 2014. LOS was compared for each of three CCGs in our Trust's catchment areas, and those patients admitted from outlying CCGs. Sub-analysis was performed by patient age, ASA grade, abbreviated mental test score, procedure type and discharge destination to determine which factors influence LOS.

RESULTS

1847 patients were identified. After excluding deaths, missing data and extreme outliers, 1603 patients were included in the analysis. The median LOS varied from 14.9 to 23.4 days across CCGs. The major reason for this variation was discharge destination. CCGs associated with longer LOS had a significantly higher rate of discharge to the patient's own home, rather than institutional care. This was independent of patient age, mental status, ASA grade and promptness of surgery.

CONCLUSION

We have shown that CCGs vary in their performance to aid discharge. This directly influences a Trust's performance on the National Hip Fracture Database. Compared with other hospitals, our results show a poor outcome in terms of length of stay, but much better performance regarding home discharge. We recommend that more emphasis in future be placed on discharge destination than LOS.

The clinical efficacy of triclosan/copolymer and other common therapeutic approaches to periodontal health

The maintenance of an effective level of oral hygiene is the cornerstone of all attempts to prevent and control periodontal disease, and yet the widespread prevalence of the disease indicates the inability of most people to maintain a level of plaque control commensurate with periodontal health. The inclusion of antibacterial agents, such as chlorhexidine and triclosan, in oral care products has provided a means to improve oral health. Randomised, controlled clinical trials have demonstrated that the unsupervised use of a dentifrice (toothpaste) containing triclosan/copolymer significantly improves gingival health, prevents the onset of periodontitis and reduces further progression of tissue destruction. The delivery of such benefits has positive implications for the oral health of individuals and populations.

A cluster randomised controlled trial to evaluate the effectiveness of fluoride varnish as a public health measure to reduce caries in children

This cluster randomised controlled study assessed the effectiveness of twice-yearly applications of fluoride varnish as a public health measure to reduce dental caries in children living in relatively deprived communities. The test (n = 334) and control (n = 330) children in 2 school years (unit of randomisation) attended 24 state primary schools and were 6-8 years of age at the start. Good baseline balance was found. Duraphat varnish was applied at school on 5 occasions over 26 months, by dental therapists. A combined visual and fibre-optic transillumination examination included all surfaces of primary and first permanent molars at baseline and after 26 months for small and large enamel and dentine lesions. At the final examination the only statistically significant difference was in the caries increment for small enamel lesions in the primary dentition, with the test children having fewer lesions. This study failed to demonstrate that the twice-yearly application of fluoride varnish provided at school reduced dental caries in children living in this community. The low level of response and a lower than expected caries increment had a major impact on the effectiveness of the intervention, since the children who participated were least likely to have benefited from the programme, whereas those who might have benefited did not consent.

Challenges associated with the evaluation of a dental health promotion programme in a deprived urban area

OBJECTIVE

This paper reports the results of a community trial to measure the clinical impact of a linked series of interventions on Early Childhood Caries (ECC) and general caries levels among five-year-old children. It exemplifies the problems of undertaking population based interventions in deprived communities.

RESEARCH DESIGN

Two health districts (Primary Care Groups) were matched for dental disease levels and socio-demographic factors. One was randomly allocated to be the active intervention PCG, the other the comparison PCG. Children in the active PCG received a series of interventions to support positive dental health behaviour from the age of 8 to 32 months. Clinical examinations were undertaken on a cohort of 5-year-old children in both active and comparison PCGs.

SETTING

In the active PCG, children who attended designated clinics for their 8-month developmental checks and/or MMR inoculations at 12 to 15 months, were given gift bags, the first contained a trainer cup, the second fluoride toothpaste (1450 ppm F) and toothbrush. Parents were also given written, pictorial and verbal advice on oral care. Further supplies of toothpaste and brushes were posted to the children's homes at 20, 26 and 32 months. When five years of age children in the two PCGs were examined in school.

OUTCOME MEASURES

Severity and prevalence of ECC and general caries. Levels of participation.

RESULTS

Among participants in the active PCG the prevalence of ECC, general caries and extraction experience and mean dmft (20%: 54%: 3%: 2.2) were lower than in 'participants' in the comparison area (32%: 64%: 12%: 3.7). All differences were statistically significant. When all children (participants and non-participants) in the two PCGs were compared, the differences were much reduced (30%: 63%: 6%: 3.1 vs. 32%: 64%: 12%: 3.6). A higher proportion of children in the active PCG area (47%) were found not to have participated in the interventions, when compared to 21% in the comparison area. Disease levels in the non-participants in the active PCG were particularly high. The impact of participation bias, changes in baseline balance, population mobility and alternative study design on outcomes are explored.

CONCLUSION

The impact of non-participation in a deprived, urban conurbation with high levels of population mobility are sufficient to dilute the impact of a health intervention such that few benefits are discernible at a population level.

Agreement amongst examiners assessing dental fluorosis from digital photographs using the TF index

OBJECTIVE

To compare the scoring of dental fluorosis by experienced examiners from digital photographs using the TF index.

BASIC RESEARCH DESIGN

120 images were selected from 703 photographs obtained during a clinical trial (Tavener et al., 2004). The selection process was stratified so that the full range of defects seen in the main study was included. The children, aged 8-10 years, were from deprived areas of Manchester, England with fluoride levels in the drinking water of less the 0.1 ppm F. The photographs of the upper and lower anterior sextants were taken after cleaning and drying the teeth. The examiners were identified by searching Medline for individuals who had previously used the TF index or had experience of scoring dental fluorosis. Of the 12 examiners identified, 10 agreed to take part. Each examiner was provided with identical CDs containing a PowerPoint presentation of the images. Twelve images were duplicated and interspersed amongst the 120 images to assess intra examiner agreement. Each examiner was also supplied with a table listing the criteria and illustrations for each of the TF index scores (Fejerskov et al., 1988).

RESULTS

The prevalence of fluorosis (TF > 0) amongst the 10 examiners ranged from 43% to 70% and from 2% to 13% for the more severe scores (TF 3 or 4). Paired agreements amongst subject scores for the 10 examiners, measured using a weighted Kappa score, ranged from 0.40 to 0.71.

CONCLUSION

It is concluded that although the criteria for the TF index are well defined, it is possible that examiners may interpret the criteria in different ways and conditions in which images are viewed may need to be standardised. This study may explain some of the differences in the prevalence and severity of fluorosis reported in different studies. There is a need to standardise the methods used to score dental fluorosis.

Effect of whitening gels on the surface roughness of restorative materials in situ

Peroxide gels are effective in changing tooth colour but their effect on restorative materials has been poorly studied. The purpose of this investigation was to assess the impact of a commercially available whitening gel containing hydrogen peroxide and a sodium percarbonate formulation on the surface of restorative materials. A total of 12 subjects participated in a double-blinded crossover study. Each wore an intra-oral appliance containing five bovine enamel blocks restored with amalgam, posterior composite, microfilled composite, glass ionomer cement and porcelain. Appliances were worn continuously for 14 days and whitening products were applied twice daily. After 14 days the appliances were removed and values for roughness (R(a)) were obtained using atomic force microscopy. Mean values of R(a) were assessed between baseline and 14 days, and although minor variations were seen, there were no statistically significant differences detected for any material or any whitening product.

The Effects of Illumination and Focal Distance on Light-Induced Fluorescence Images in vitro

When using quantitative light-induced fluorescence a number of factors can influence illumination level. The purpose of this study was to investigate, using a high-resolution camera and fibre-optic light source, the impact of illumination level and focal distance on common quantitative light-induced fluorescence outcomes. Twenty-four extracted teeth were examined using 6 illumination levels and 4 focal distances. Analysis was conducted using multiple linear regression models fitted to log DeltaQ, log DeltaF and log area with clustering of teeth and robust standard errors. Separate models were used for the different light and focal levels. The regression coefficients were significant for both DeltaQ and DeltaF but not area. Despite the significant regressions the actual effect was very small, and unlikely to confound clinical trial or practice results.

The Prevalence and Severity of Fluorosis in Children Who Received Toothpaste Containing either 440 or 1,450 ppm F from the Age of 12 Months in Deprived and Less Deprived Communities

This study compared fluorosis in the upper central incisors of children from socially diverse backgrounds who had received either 440- or 1,450-ppm F toothpaste from 12 months of age. The children were resident in non-fluoridated districts in the north-west of England. They received either 440- or 1,450-ppm F toothpaste and advice regarding its use until the age of 5-6 years. Dental fluorosis (TF index) was assessed on digital images of dried teeth when the children (n = 1,268) were 8-10 years old. In the less deprived districts the prevalences of fluorosis (TF >or=0) for the 1,450- and 440-ppm F groups were 34.5 and 23.7% (p = 0.006). In the deprived districts the prevalences of fluorosis were 25.2 and 19.5% (p = 0.2). Overall the prevalences of TF >or=2 were 7 and 2.1% for the 1,450- and 440-ppm F groups and 2.2 and 0.2% for TF >or=3. These differences were statistically significant (p < 0.003). There was a strong association between the deprivation status of wards and fluorosis. Only 1 subject with a TF score of 3 was identified in the two most deprived quintiles of the Townsend score. It is concluded that careful targeting of programmes of this type to children living in high caries risk deprived communities carries only a small risk of aesthetically objectionable fluorosis (TF >2) whether low or high fluoride toothpastes are used. High fluoride (1,450 ppm F) toothpastes should not be provided on a community basis to very young children in less deprived communities.

The effect of video repositioning on the reliability of light-induced fluorescence imaging: an in vivo study

The ability to monitor longitudinally the development, arrest or resolution of early demineralised lesions is one strength of quantitative light-induced fluorescence (QLF). When taking sequential images of an individual's teeth for monitoring it has been suggested that the subsequent images should be taken from the same position the baseline image. To assist in this process, video repositioning software is available that enables automatic capture of images once the system identifies that they are similar enough to the baseline comparator. The purpose of this study was to determine if the use of such software-assisted capture improves the reliability of subsequent QLF analysis. 20 subjects had 34 surfaces (buccal and occlusal) imaged by 2 examiners at baseline, and again 1 week later using both manual and software-assisted (VidRep) systems. Analysis of the three key reportable values for QLF (DeltaF, lesion area, DeltaQ) suggested that there is no significant improvement in reliability using VidRep although VidRep demonstrates additional advantages above and beyond image geometry, relating to the speed of subsequent image analysis.

A staged intervention dental health promotion programme to reduce early childhood caries

OBJECTIVE

This paper reports the results of a community trial to assess the effects of a multi-stage dental health promotion programme in reducing Early Childhood Caries (ECC).

RESEARCH DESIGN

Two health districts (Primary Care Groups) were matched for dental disease levels and socio-demographic factors. One was randomly allocated to be the test Primary Care Group (PCG), the other the control PCG. Children in the test PCG received a series of interventions to support positive dental health behaviour from the age of 8 to 32 months. Interviews were conducted with parents of children aged 21 months and clinical examinations were undertaken on a larger cohort of children aged 3-4 years in test and control PCGs.

SETTING

The interventions were gift bags containing a trainer cup, toothpaste containing 1,450 ppm F and toothbrush, and advice given to the children's parents on attendance at designated clinics and medical practices and further paste and brushes posted to the children's homes. Parents were interviewed on the telephone. Examinations took place at Children's Centres and nursery departments attached to primary schools.

OUTCOME MEASURES

Severity and prevalence of ECC and general caries and proportion of parents reporting adopting dentally healthy behaviours.

RESULTS

In the test PCG the prevalence of ECC in children who had received the interventions was 16.6% compared with 23.5% of children in the control area, a reduction of 29% (p=0.003). The mean dmft (1.17) and prevalence of general caries experience (28.7%) in the test children were also significantly lower than for children in the control PCG (1.72: 39.2%) (p=0.001). Analysis from a community perspective, which included data from all children examined in both areas, showed the prevalence of ECC in the test and control PCGs was 21.3% and 22.8% respectively and the mean dmft 1.47 and 1.72. The proportion with general caries experience remained statistically significant in favour of the test area 33.8% vs 39.9% (p=0.01). Parents in the test PCG were more likely to report cessation of bottle use (33% vs 18%), use of sugar-free drinks (49% vs 24%), commencement of brushing before first birthday (45% vs 27%) and twice daily brushing (52% vs 34%).

CONCLUSION

The parents who received this multi-stage intervention were more likely to report adoption of three positive oral health behaviours; using a trainer cup from one year of age, using safe drinks and brushing twice daily with a fluoride toothpaste. The programme failed to reduce the prevalence of ECC in the community but the prevalence of ECC and general caries experience among the children who participated was less than among children in the control PCG.

The effectiveness of a toothpaste containing Triclosan and polyvinyl-methyl ether maleic acid copolymer in improving plaque control and gingival health. A systematic review

OBJECTIVE

To compare the effectiveness of triclosan/copolymer and fluoride dentifrices in improving plaque control and gingival health.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register, MEDLINE (1986 to March 2003) and EMBASE (1986 to March 2003). Personal files and the reference lists of all articles were checked for further studies.

SELECTION CRITERIA

Trials were selected if they met the following criteria: random allocation of participants; participants were adults with plaque and gingivitis; unsupervised use of dentifrices for at least 6 months; and primary outcomes - plaque and gingivitis after 6 months.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted information. For each plaque and gingivitis index, the mean differences for each study were pooled as weighted mean differences (WMDs) with the appropriate 95% confidence intervals (CIs) using the random effect models.

MAIN RESULTS

Sixteen trials provided data for the meta-analysis. The triclosan/copolymer dentifrice significantly improved plaque control compared with a fluoride dentifrice, with a WMD of -0.48 (95% CI: -0.64 to -0.32) for the Quigley-Hein index and WMD of -0.15 (95% CI: -0.20 to -0.09) for the plaque severity index. When compared with a fluoride dentifrice, the triclosan/copolymer dentifrice significantly reduced gingivitis with WMDs -0.26 (95% CI: -0.34 to -0.18) and -0.12 (95% CI: -0.17 to -0.08) for the Loe and Silness index and gingivitis severity index, respectively.

Predictors of outcome for orofacial pain in the general population: a four-year follow-up study

Orofacial pain is often persistent, but it is not clear why it lasts in some patients but not in others. We aimed to describe the natural course of orofacial pain in a general population sample over a four-year period and to identify factors that would predict the persistence of pain. A cross-sectional population-based survey was conducted in the United Kingdom, involving 2504 participants (participation rate 74%), of whom 646 (26%) reported orofacial pain. Overall, 424 (79% adjusted participation rate) of these individuals participated at the four-year follow-up, of whom 229 (54%) reported orofacial pain and 195 (46%) did not report such pain. Persistent orofacial pain was associated with females, older age, psychological distress, widespread body pain, and taking medication for orofacial pain at baseline. These findings may have implications for the identification and treatment of patients with orofacial pain.

The prevalence and severity of fluorosis and other developmental defects of enamel in children who received free fluoride toothpaste containing either 440 or 1450 ppm F from the age of 12 months

OBJECTIVE

To assess the impact of a programme regularly supplying free fluoride toothpaste to children on the prevalence and severity of fluorosis and other developmental defects of enamel.

DESIGN

Randomised, controlled, parallel three-group clinical trial. Two groups received toothpaste containing either 440 or 1450 ppm F; the third group received no intervention. Children were supplied with toothpaste and advice on its use from the age of 12 months until they were 5-6 years old. The participants were a sub sample of those involved in a study that considered the caries benefits of providing free fluoride toothpaste. They were eligible if they completed the main study, lived in four of the nine districts involved and attended schools with 6 or more eligible participants.

SETTING

Children from the north west of England consuming drinking water containing less than 0.1 ppm F were examined in primary schools.

PARTICIPANTS

3731 children completed the main study. Of the 1833 children in the four selected districts, 927 were from schools with six or more participants.

METHOD

Digital images encompassing the upper and lower anterior sextants were taken of each child when they were 8-9 years old.

MAIN OUTCOME MEASURES

Developmental defects of enamel and dental fluorosis (TF index) were recorded on upper central incisors from wet and dry images.

RESULTS

A total of 703 children were included in the data analysis. In the 1450 ppm F (n=218), 440 ppm F (n = 226) and control (n = 259) groups the prevalence of dental fluorosis (TF > 0) was 17%, 15% and 12% for the wet (p > 0.05) and 26%, 24% and 25% for the dry (p > 0.05) photographs respectively. The prevalence of TF scores 2 or 3 (highest score) was 5%, 4% and 2% and for the wet (p > 0.05) and 7%, 4% and 5% for the dry (p > 0.05) photographs respectively. All subjects identified with TF score 3 were found in the group using the 1450 ppm F toothpaste (3 wet and 4 dry) and there were statistically significant differences between the three groups for both wet (p = 0.03) and dry photographs (p < 0.01). However, the pairwise comparisons between the groups failed to attain statistical significance. The highest prevalence and severity of demarcated opacities was seen in the control group and for the wet photographs the difference between the three groups attained statistical significance (p = 0.04). For both the wet and dry photographs the prevalence of any enamel defects (including fluorosis) and large demarcated or TF score 3 was similar for the three groups (p > 0.05).

CONCLUSION

Previously it has been reported that only the provision of 1450 ppm F toothpaste provides anticaries benefits in a programme of this type. This benefit is accompanied by a slight increase in prevalence of TF score 3 but not the overall prevalence of developmental defects of enamel. Careful targeting and implementation of a programme of this type is required to maximise benefits and minimise risks of fluoride exposure.

The rational use of fluoride toothpaste

Well-formulated fluoride toothpastes are clinically proven to prevent and control dental caries. They may also be a risk factor in the aetiology of dental fluorosis. This review considers the available evidence to support the appropriate use of fluoride toothpaste to maximise the benefit and minimise the risk. Three factors have an important influence on the anticaries efficacy of fluoride toothpaste, namely concentration, frequency of brushing and post brushing rinsing behaviour. The evidence suggests that low-fluoride (<600 ppm F) toothpastes provide less caries protection than standard (1,000 ppm F) or high (1,500 ppm F) concentration formulations. However, low-fluoride toothpastes are appropriate for very young children (under 7 years) at low caries risk, particularly if living in fluoridated areas. For other young children, higher concentrations of fluoride should be used. Brushing should be recommended twice daily, whilst rinsing with large volumes of water should be discouraged. Small amounts of toothpaste are comparable in efficacy to large amounts. The risk of fluorosis is associated with the ingestion of high doses of fluoride during tooth development and consequently only young children are at risk. The variability in the dose of fluoride ingested is mainly a function of the amount used, less so its concentration. To minimise fluorosis risk, parents should be advised to use only a pea-sized amount of toothpaste and encourage spitting out of excess. It is concluded that by using fluoride toothpastes appropriately, the benefits can be maximised and the risks of fluorosis minimised.

A new look at fluoride varnishes

Fluoride varnishes have been available for over 30 years but there may be clinicians and dental public health practitioners who are unaware of the true level of effectiveness they provide in caries control. Under the headings of effectiveness, ease of application and safety the available evidence is digested and summarized to inform the reader about the indications, method of use and alternative options for caries control.

Relationship between area deprivation and the anticaries benefit of an oral health programme providing free fluoride toothpaste to young children

OBJECTIVE

To determine the effectiveness of providing free toothpaste containing either 1450 or 440 ppm F on caries experience in 5-year-old children living in areas with different levels of material deprivation.

DESIGN

Five-year, examiner-blind, randomized, controlled, parallel-group, clinical trial. Children were randomly assigned to three groups.

SETTING

Health Districts in the north-west of England with high levels of dental caries. Clinical examinations were performed in schools during the period October 1999 to April 2000 when the children were 5-6 years old.

PARTICIPANTS

Children from 3-month birth cohorts resident in nine, nonfluoridated health districts.

INTERVENTIONS

Toothpaste containing either 440 or 1450 ppm F and dental health literature posted at 3-month intervals and toothbrush provided annually from the age of 1-5 years. Comparison group received no intervention.

MAIN OUTCOME MEASURES

Mean dmft and proportion of participants with dmft > 0, dmft > or = 4, upper primary incisor caries and extraction of one or more primary teeth. Outcomes tabulated for quartiles of participants based on the distribution of the Townsend index of material deprivation.

RESULTS

A total of 3467 children were included in the final data analysis. The Townsend index was found to be useful in identifying groups of children with increased caries risk. Overall, participants in the programme using the high-fluoride toothpaste had significantly (P < 0.002) less caries than the comparison group with similar absolute reductions in mean dmft for the most- and least-deprived groups. Relative to the comparison group the association between deprivation and dental caries was changed so that in the most-deprived quartile those using the low-fluoride toothpaste tended to have less dental caries than the comparison group whereas in the least deprived they tended to have more. This difference in the association (slope) was statistically significant (P < 0.05). Provision of both low- and high-fluoride toothpaste appeared to reduce the risk of extractions for participants in the most-deprived quartile (P < 0.05).

CONCLUSION

The relative benefits of the programmes supplying the two toothpastes considered in this study are different depending on the deprivation status of the participants. For the most-deprived groups postal provision of either a low- or high-fluoride toothpaste provides similar levels of benefit. In the less deprived groups only provision of the high-fluoride toothpaste provided a benefit. The absolute caries reduction seen for provision of the high-fluoride toothpaste was not related to the deprivation status and hence the programme did not reduce deprivation-related health inequalities. Targeting the programme using the methods employed in this study is unlikely to improve the effectiveness of the programme.

Thermal effects of the Er:YAG laser on a simulated dental pulp: a quantitative evaluation of the effects of a water spray

OBJECTIVES

To quantify the temperature increments in a simulated dental pulp following irradiation with an Er:YAG laser, and to compare those increments when the laser is applied with and without water spray.

METHODS

Two cavities were prepared on either the buccal or lingual aspect of sound extracted teeth using the laser. One cavity was prepared with water spray, the other without and the order of preparation randomised. Identical preparation parameters were used for both cavities. Temperature increments were measured in the pulp chamber using a calibrated thermocouple and a novel pulp simulant.

RESULTS

Maximum increments were 4.0 degrees C (water) and 24.7 degrees C (no water). Water was shown to be highly significant in reducing the overall temperature increments in all cases (p<0.001; paired t-test). None of the samples prepared up to a maximum of 135 J cumulative energy prepared with water spray exceeded that threshold at which pulpal damage can be considered to occur. Only 25% of those prepared without water spray remained below this threshold.

DISCUSSION

Extrapolation of the figures suggests probably tolerable limits of continuous laser irradiation with water in excess to 160 J. With the incorporation of small breaks in the continuity of laser irradiation that occur in the in vivo situation, the cumulative energy dose tolerated by the pulp should far exceed these figures.

CONCLUSIONS

The Er:YAG laser must be used in conjunction with water during cavity preparation. As such it should be considered as an effective tool for clinical use based on predicted pulpal responses to thermal stimuli.

An assessment of the cost effectiveness of a postal toothpaste programme to prevent caries among five-year-old children in the North West of England

OBJECTIVE

To assess the cost effectiveness of a postal toothpaste programme to prevent caries in 5-year-old children in the north west of England.

PARTICIPANTS

Birth cohorts of children aged 12 months were recruited from high caries risk populations in nine health districts.

DESIGN

The results of a randomised controlled trial to measure the effects of a postal toothpaste programme are used and related to the costs of running a similar programme. Children in the trial received free toothpaste on four occasions a year and a toothbrush once a year for four years from age 12 months to 5 years. When aged 5-6 years children were examined by trained, calibrated examiners using BASCD standards. Those who received toothpaste containing 1450 ppm F were found to have a significantly lower mean dmft than those who had not. The costs that would be incurred by a public dental service running such a postal toothpaste programme are identified, measured and related to the likely health improvement that could be achieved.

MAIN OUTCOME MEASURES

The cost per tooth saved and the cost per child saved from caries experience and extraction experience.

RESULTS

The estimated cost per tooth saved from carious attack was pounds sterling 80.83 and the cost per child of preventing caries experience was pounds sterling 424.38 and avoiding any extractions was pounds sterling 679.01. Analysis resulted in an overestimation of costs and underestimation of benefits.

CONCLUSION

The programme achieved a significant caries reduction in children who received the 1450 ppm F toothpaste and the costs are now available to those considering provision of treatment services in areas where children are at high caries risk.

Association between local mechanical factors and orofacial pain: survey in the community

OBJECTIVES

The aetiology of orofacial pain (OFP) is not well understood. We aimed to determine the relationship between OFP and local mechanical factors in an unselected general population sample.

METHODS

A cross-sectional population-based survey was conducted in the United Kingdom, involving 2504 participants (adjusted participation rate 74%). Postal questionnaire was used to collect information on OFP and local mechanical factors.

RESULTS

A significant association was found between OFP and a history of tooth grinding, facial trauma, the jaw getting stuck or locked, a clicking or grating sound in the jaw joint when opening or closing the mouth, difficulty in opening the mouth wide, and chewing of pens or biting finger nails. The jaw getting stuck or locked had the highest relative risk of 2.7 (95% CI: 2.3-3.2). A history of orthodontic treatment, having any type of dentures and using chewing gum were not associated with OFP. There was some evidence of heterogeneity between types of OFP and local mechanical factors.

CONCLUSIONS

Local factors play an important role in the aetiology of OFP.

The rational use of oral care products in the elderly

This review examines the evidence of the effectiveness of oral care products in preventing and controlling dental caries and periodontal disease in the ageing population. The strength of evidence is indicated using the following hierarchy: Type 1 (systematic reviews), Type 2 (randomised controlled trials), Type 3 (observational studies) and Type 4 (traditional reviews). Most of the evidence to support the effectiveness of fluoride products is extrapolated from studies involving children and adolescents. The few studies that have been performed in older adults suggest that fluoride toothpaste and, in the case of high caries risk individuals, the adjunctive use of other fluoride delivery systems, may be effective in preventing coronal and root caries. Some dentifrices containing triclosan have been shown to improve plaque control and gingival health and one, which contains triclosan/copolymer, reduces the progression of periodontitis in adults and high-risk individuals. Powered toothbrushes with an oscillation-rotation action are more effective in reducing plaque and improving gingival health than manual toothbrushes.

Factors associated with health care seeking behaviour for orofacial pain in the general population

OBJECTIVE

To describe the health care seeking behaviour associated with orofacial pain (OFP) and determine factors associated with such behaviour.

DESIGN

Cross-sectional population-based study using postal questionnaires.

PARTICIPANTS

Adults aged 18-64 years from a general medical practice in south-east Cheshire, UK (participation rate 74%).

RESULTS

Of the 2,504 respondents to the questionnaire 646 reported OFP, of whom 555 (86%) indicated whether or not they sought professional help. A total of 255 (46%) responded that they had sought advice. The majority had sought advice from their medical practitioner (57%) or dentist (51%), and 64% had taken medication because of OFP. The likelihood of seeking treatment increased linearly with age (p < 0.001) while gender, education and psychological distress did not show a significant association with seeking treatment. Persons who were regular dental attenders had an increased likelihood of seeking treatment for OFP (RR 1.4; 95% CI 1.1,1.8). Perception of illness had moderate association with healthcare seeking (RR 0.8; 95% CI 0.7,0.96). There was a significant trend of increasing RR with increasing total number of pain symptoms (p < 0.001), frequency of pain, duration of pain episodes, pain intensity and disability associated with pain. Participants who reported pain duration of more than three months had almost double the likelihood (RR 1.8; 95% CI 1.4,2.3) of seeking treatment. Decrease in self-reported control over pain and ability to decrease pain were both associated with an increased likelihood of seeking professional care (p < 0.001).

CONCLUSIONS

The strongest predictors of health care seeking behaviour were different characteristics of pain.

A randomised controlled trial of the effectiveness of providing free fluoride toothpaste from the age of 12 months on reducing caries in 5-6 year old children

OBJECTIVE

To assess the impact of regularly supplying free fluoride toothpaste regularly to children, initially aged 12 months, and living in deprived areas of the north west of England on the level of caries in the deciduous dentition at 5-6 years of age. A further aim was to compare the effectiveness of a programme using a toothpaste containing 440 ppmF (Colgate 0-6 Gel) with one containing 1,450 ppmF (Colgate Great Regular Flavour) in reducing caries.

DESIGN

Randomised controlled parallel group clinical trial. Clinical data were collected from test and control groups when the children were 5-6 years old.

SETTING

A programme of posting toothpaste with dental health messages to the homes of children initially aged 12 months. Clinical examinations took place in primary schools.

PARTICIPANTS

7,422 children born in 3-month birth cohorts living in high caries areas in nine health districts in north west England. Within each district children were randomly assigned to test or control groups.

INTERVENTIONS

Toothpaste, containing either 440 ppmF or 1450 ppmF, and dental health literature posted at three monthly intervals to children in test groups until they were aged 5-6 years.

MAIN OUTCOME MEASURES

The dmft index, missing teeth and the prevalence of caries experience.

RESULTS

An analysis of 3,731 children who were examined and remained in the programme showed the mean dmft to be 2.15 for the group who had received 1,450 ppmF toothpaste and 2.49 for the 440 ppmF group. The mean dmft for the control group was 2.57. This 16% reduction between the 1,450 ppmF and control group was statistically significant (P<0.05). The difference between the 440 ppmF group and control was not significant. Further analyses to estimate the population effect of the programme also confirmed this relationship.

CONCLUSION

This study demonstrates that a programme distributing free toothpaste containing 1,450 ppmF provides a significant clinical benefit for high caries risk children living in deprived, non-fluoridated districts.

Association between female hormonal factors and oro-facial pain: study in the community

The aim of this study was to determine the relationship between the prevalence of oro-facial pain (OFP) in the population and female hormonal factors. The cross-sectional population study was conducted in a general medical practice in the north-west of England. A random sample of 4000 adults aged 18-65 years were mailed questionnaires, of whom 2504 responded (adjusted participation rate 74%). Of these 1245 women provided information on both OFP and hormonal factors. For pre- or peri-menopausal women, there was no relationship between oral contraceptive use and OFP (age-adjusted relative risk (RR) 1.10; 95% confidence interval (CI) 0.81, 1.45), whilst a high score on a pre-menstrual symptom questionnaire was associated with an age-adjusted RR of 1.87 (95% CI 1.36, 2.57). Those who reported menstruating for 6 days or longer had moderate increase in risk of OFP (age-adjusted RR 1.39; 95% CI 1.01, 1.91). In post-menopausal women, there was a moderate relationship between hormone replacement therapy use and OFP (age-adjusted RR 1.46; 95% CI 1.02, 2.08). For women overall, there was an increased risk of OFP in those who reported ever having had painful periods (age-adjusted RR 1.47; 95% CI 1.20, 1.80), but no association was found with the number of children. This cross-sectional community-based study adds important information on the relationship between female hormonal factors and OFP. Women who report OFP are more likely to report symptoms associated with menstruation. This may indicate either the importance of hormones per se or identify a group of women who are more likely to report symptoms in general.

Sex hormonal factors and chronic widespread pain: a population study among women

OBJECTIVE

The observation of higher rates of chronic widespread pain, the cardinal feature of fibromyalgia, in women has led to hypotheses about the role of sex hormonal factors in the aetiology of symptoms. There is little available evidence from epidemiological studies on their importance or role.

METHODS

A population postal survey was carried out involving 1178 female participants living in south-east Cheshire in the north-west of England.

RESULTS

Amongst pre- and peri-menopausal women, the risk of chronic widespread pain was unrelated either to the length of the menstrual cycle or the usual length of period reported by participants. Risk was similar in current users and non-users of the oral contraceptive pill, and amongst users there was no relationship with duration of use. However, the reporting of chronic widespread pain showed a relationship with total score on a premenstrual symptom questionnaire. However, this relationship was explained by pain symptoms. Amongst post-menopausal women, reporting chronic widespread pain was not related to age at menopause. An increased (but non-significant) risk of chronic widespread pain was associated with current hormone replacement therapy (HRT), which may be a consequence of HRT being prescribed for menopausal symptoms.

CONCLUSION

This study, conducted on a large unselected population, has not demonstrated an association between sex hormonal factors and chronic widespread pain.

Complete genome sequence of a multiple drug resistant Salmonella enterica serovar Typhi CT18

Salmonella enterica serovar Typhi (S. typhi) is the aetiological agent of typhoid fever, a serious invasive bacterial disease of humans with an annual global burden of approximately 16 million cases, leading to 600,000 fatalities. Many S. enterica serovars actively invade the mucosal surface of the intestine but are normally contained in healthy individuals by the local immune defence mechanisms. However, S. typhi has evolved the ability to spread to the deeper tissues of humans, including liver, spleen and bone marrow. Here we have sequenced the 4,809,037-base pair (bp) genome of a S. typhi (CT18) that is resistant to multiple drugs, revealing the presence of hundreds of insertions and deletions compared with the Escherichia coli genome, ranging in size from single genes to large islands. Notably, the genome sequence identifies over two hundred pseudogenes, several corresponding to genes that are known to contribute to virulence in Salmonella typhimurium. This genetic degradation may contribute to the human-restricted host range for S. typhi. CT18 harbours a 218,150-bp multiple-drug-resistance incH1 plasmid (pHCM1), and a 106,516-bp cryptic plasmid (pHCM2), which shows recent common ancestry with a virulence plasmid of Yersinia pestis.

A cluster randomized controlled trial testing the effectiveness of a school-based dental health education program for adolescents

OBJECTIVES

This trial investigated the value of a school-based dental health education program in terms of changes in knowledge, reported behavior, and plaque scores.

METHODS

A total of 2,678 pupils with a mean age of 12.1 years attending 28 schools participated in a school-based dental health education program. The study used a cluster randomized controlled study design. The health service administrators stipulated that all participants receive the intervention; to meet this requirement, a rolling program of two six-month periods was utilized. During the first six months, half the adolescents received the intervention program, the other half acting as controls. Throughout a further six-month period, all participants received the intervention program. This research design allowed comparisons between participants receiving the program for six and 12 months. At baseline, six, and 12 months, a random subsample of 40 children in each participating school had their plaque scores recorded and a questionnaire was used to record their knowledge of dental health and reported dental behavior.

RESULTS

The analysis used the subjects clustered within the schools, which were the units of randomization. The intervention program produced statistically significant improvements (P < .001) in knowledge about periodontal disease and the frequency of sugar intake and dental caries in both assessment time periods. The reported frequency of brushing did not change, but the group who had received 12 months of the intervention were more likely (P < .05) to brush for over a minute. At six months the early intervention group had a statistically significant, 13 percent reduction in the mean proportion of sites with plaque compared with the late intervention group (P = .043). This difference was sustained at 12 months (P = .037).

CONCLUSION

This cluster randomized control trial demonstrated that the intervention program resulted in an improvement in knowledge of dental disease and an increase in the reported duration of brushing. These improvements were accompanied by a significant improvement in oral hygiene and a reported reduction in gingival bleeding.

Genome sequence of Yersinia pestis, the causative agent of plague

The Gram-negative bacterium Yersinia pestis is the causative agent of the systemic invasive infectious disease classically referred to as plague, and has been responsible for three human pandemics: the Justinian plague (sixth to eighth centuries), the Black Death (fourteenth to nineteenth centuries) and modern plague (nineteenth century to the present day). The recent identification of strains resistant to multiple drugs and the potential use of Y. pestis as an agent of biological warfare mean that plague still poses a threat to human health. Here we report the complete genome sequence of Y. pestis strain CO92, consisting of a 4.65-megabase (Mb) chromosome and three plasmids of 96.2 kilobases (kb), 70.3 kb and 9.6 kb. The genome is unusually rich in insertion sequences and displays anomalies in GC base-composition bias, indicating frequent intragenomic recombination. Many genes seem to have been acquired from other bacteria and viruses (including adhesins, secretion systems and insecticidal toxins). The genome contains around 150 pseudogenes, many of which are remnants of a redundant enteropathogenic lifestyle. The evidence of ongoing genome fluidity, expansion and decay suggests Y. pestis is a pathogen that has undergone large-scale genetic flux and provides a unique insight into the ways in which new and highly virulent pathogens evolve.

The use of fibre-optic transillumination in general dental practice

OBJECTIVE

To assess the use of fibre-optic transillumination (FOTI) as a diagnostic tool in general dental practice.

DESIGN

A cross-over quantitative study for the diagnosis of approximal carious lesions by two clinical methods with a qualitative component.

SUBJECTS AND METHODS

Seven GDPs were trained to use FOTI as an adjunct to their usual clinical examination to diagnose approximal caries. After 12 weeks of use in their practices four of the GDPs took part in two assessment sessions, set a week apart, using 29 volunteer patients. Each patient was examined on two separate occasions by each GDP using either their standard clinical examination technique alone or supplemented by FOTI examination. The order of the techniques was randomised. Radiographs of each patient were also examined separately. An experienced FOTI user also examined the patients to provide a benchmark. From standard charts the number of enamel and dentinal lesions on approximal surfaces was summed and comparisons made between the techniques. Six GDPs took part in one-to-one interviews.

MAIN OUTCOME MEASURES

Mean numbers ofcarious lesions recorded by each clinician using each technique.

RESULTS

There was a trend for all GDPs to find more enamel and dentinal lesions using FOTI, than with their standard clinical examination with or without radiographs. All GDPs found the FOTI technique a useful adjunct. They used FOTI in different ways and found a variety of uses for it other than caries diagnosis.

CONCLUSIONS

The

Mutation of the gene encoding the enamel-specific protein, enamelin, causes autosomal-dominant amelogenesis imperfecta

Amelogenesis imperfecta (AI) is a group of inherited defects of dental enamel formation that shows both clinical and genetic heterogeneity. To date, mutations in the gene encoding amelogenin have been shown to underlie a subset of the X-linked recessive forms of AI. Although none of the genes underlying autosomal-dominant or autosomal-recessive AI have been identified, a locus for a local hypoplastic form has been mapped to human chromosome 4q11-q21. In the current investigation, we have analysed a family with an autosomal-dominant, smooth hypoplastic form of AI. Our results have shown that a splicing mutation in the splice donor site of intron 7 of the gene encoding the enamel-specific protein enamelin underlies the phenotype observed in this family. This is the first autosomal-dominant form of AI for which the genetic mutation has been identified. As this type of AI is clinically distinct from that localized previously to chromosome 4q11-q21, these findings highlight the need for a molecular classification of this group of disorders.

The contribution of industry to the decline in dental caries

The contribution of the oral care industry to the reduction in dental caries extends beyond the provision of safe and clinically proven products containing fluoride. The industry has contributed to the scientific base that underpins the use of fluoride, delineated factors that influence the clinical performance of toothpaste, raised the public's awareness of dental health and provided funding to support both undergraduate and postgraduate students in clinical training and basic research.

Massive gene decay in the leprosy bacillus

Leprosy, a chronic human neurological disease, results from infection with the obligate intracellular pathogen Mycobacterium leprae, a close relative of the tubercle bacillus. Mycobacterium leprae has the longest doubling time of all known bacteria and has thwarted every effort at culture in the laboratory. Comparing the 3.27-megabase (Mb) genome sequence of an armadillo-derived Indian isolate of the leprosy bacillus with that of Mycobacterium tuberculosis (4.41 Mb) provides clear explanations for these properties and reveals an extreme case of reductive evolution. Less than half of the genome contains functional genes but pseudogenes, with intact counterparts in M. tuberculosis, abound. Genome downsizing and the current mosaic arrangement appear to have resulted from extensive recombination events between dispersed repetitive sequences. Gene deletion and decay have eliminated many important metabolic activities including siderophore production, part of the oxidative and most of the microaerophilic and anaerobic respiratory chains, and numerous catabolic systems and their regulatory circuits.

An SNP map of human chromosome 22

The human genome sequence will provide a reference for measuring DNA sequence variation in human populations. Sequence variants are responsible for the genetic component of individuality, including complex characteristics such as disease susceptibility and drug response. Most sequence variants are single nucleotide polymorphisms (SNPs), where two alternate bases occur at one position. Comparison of any two genomes reveals around 1 SNP per kilobase. A sufficiently dense map of SNPs would allow the detection of sequence variants responsible for particular characteristics on the basis that they are associated with a specific SNP allele. Here we have evaluated large-scale sequencing approaches to obtaining SNPs, and have constructed a map of 2,730 SNPs on human chromosome 22. Most of the SNPs are within 25 kilobases of a transcribed exon, and are valuable for association studies. We have scaled up the process, detecting over 65,000 SNPs in the genome as part of The SNP Consortium programme, which is on target to build a map of 1 SNP every 5 kilobases that is integrated with the human genome sequence and that is freely available in the public domain.

Dental fluorosis in permanent incisor teeth in relation to water fluoridation, social deprivation and toothpaste use in infancy

OBJECTIVES

To determine the prevalence and severity of fluorosis in permanent incisor teeth in young children in a fluoridated and a fluoride-deficient community and to establish what relationship, if any, there was between the occurrence of dental fluorosis and the reported use of fluoride toothpaste in childhood.

DESIGN

A prevalence study of children aged 8-9 years who had been continuous residents in fluoridated Newcastle or fluoride-deficient Northumberland.

METHOD

The permanent maxillary central incisor teeth were examined clinically and photographically by one examiner using the Thylstrup-Fejerskov index; the photographs were read blind to child identity and clinical score. A closed-response questionnaire enquired into the child's early experiences of toothbrushing and use of fluoride toothpastes. Social deprivation was measured by a Jarman score. The study took place in 1998.

OUTCOME MEASURE

Prevalence of dental fluorosis measured by the Thylstrup-Fejerskov index.

RESULTS

Complete data were available for 78% (n = 409) and 79% (n = 403) of eligible sampled children in the two areas, respectively. Clinical and photographic results agreed closely and had high reproducibility. The prevalence of fluorosis was 54% in the fluoridated area and 23% in the fluoride-deficient area when all grades (> 0) of fluorosis were included; percentage prevalence of mild to moderate fluorosis (> or = 3) was 3% and 0.5% in the two areas, respectively. Multivariate analysis indicated that area of residence (odds ratio = 4.5), Jarman score (odds ratio = 0.99 per Jarman unit) and type of toothpaste (odds ratio = 1.6) were statistically significantly related to presence or absence of fluorosis: the risk factors were--fluoridated area, affluence, and use of adult toothpaste.

CONCLUSIONS AND RECOMMENDATIONS

The prevalence of aesthetically important dental fluorosis was low, although higher in the fluoridated area. Use of a child's toothpaste (with lower fluoride concentration) could decrease risk in a fluoridated area. Adherence to the guidelines published by the British Society of Paediatric Dentistry is recommended.

An Examination of ‘Unidentified’Prevotella (Formerly PINLO) using RAPD-PCR and Partial 16S rRNA Gene Sequencing

Prevotella intermedia- and Prevotella nigrescens-like organisms (PINLO) have been described as organisms which are phenotypically and biochemically similar to P. intermedia and P. nigrescens and the species P. pallens was created to include some of them. Other PINLO groups which do not fit the definition of P. pallens exist, and in this study these 'unidentified' Prevotella sp. were compared with P. corporis, P. intermedia, P. nigrescens and P. pallens using commercial identification kits, GLC, RAPD-PCR and partial 16S rRNA gene sequencing. The Rapid ID 32 A and the RapID ANA II system both identified all 'unidentified' Prevotella as P. intermedia. Similarly they gave this identification to all the species tested (with the exception of P. corporis using the RapID ANA II system) clearly demonstrating biochemical similarities. Gas liquid chromatography (GLC) analysis of the volatile end-products of fermentation could not distinguish between strains. RAPD-PCR using arbitrary primer L10 demonstrated intra-species homogeneity within PINLO strains with amplification profiles which differed from other Prevotella species tested. Cluster analysis of the amplification profiles confirmed species divisions and yielded a distinct 'unidentified' Prevotella cluster. Comparison of partial 16S rDNA sequences displayed 98% sequence similarity between the 'unidentified' Prevotella strains, although 2 strains, HST 1156 and HST 2160 displayed 100% identity. The highest similarity between groups was seen between 'unidentified' Prevotella strains and P. corporis (approximately 94% similarity). The DNA techniques used here confirm that 'unidentified' Prevotella strains are distinct from the other species of Prevotella tested, including P. pallens. Partial 16S rDNA sequence comparisons suggested a close relationship with P. corporis.

Restorative treatment provided over five years for adults regularly attending general dental practice

OBJECTIVES

To investigate the distribution and type of restorative treatment, including re-treatment, provided for adults who attend annually.

METHODS

In 1991 a selected group of 24 general dental practitioners in the North West of England recruited 4211 of their regularly attending adult patients. Dentists recorded the reason for and type of treatment provided during the following 5 years.

RESULTS

Approximately 40% of the participants received treatment (restorations and/ or extractions) at each annual examination. Of the 2293 patients who attended every examination 1959 (85%) had received a restoration and/ or extraction during the 5 years. A total of 8187 teeth, 15% of those present at baseline, received treatment, 3030 (37%) for caries and 5157 (63%) for other reasons. The proportion of adults who received treatment by age group differed significantly with those aged 25-34 years (80%) being least likely and those 35-44 years of age (89%) most likely. Of the 1744 teeth restored in the first year of the study, 170 (10%) were retreated within 1 year and 402 (23%) during the subsequent 4 years. The 4 year survival of amalgam and tooth coloured fillings was 84% and that of crowns 92%.

CONCLUSIONS

This study documented the extent and type of restorative care provided for regularly attending adults during a 5-year period. The majority of treatment was provided for reasons other than caries. Of the teeth restored over the first year, 23% were retreated in the subsequent 4 years.

Cryopreservation and image enhancement of juvenile and adult dentine mineral

The inorganic component of bone and related hard tissues is generally described as sheets of uniform needle- and plate-like crystals. However, cryofixation has become the method of choice for ultrastructural studies of bone mineral when ladder-like arrangements of filaments contained within deformable microspheres about 1 microm in diameter are apparently the prime structural feature and are consistent with the optical image. The same methodology has now been applied to mature human dentine in caries-free juvenile and adult teeth. These were fixed, sliced, stained for mineral and examined optically or were snap frozen, fragmented under liquid nitrogen, freeze-substituted with methanol or acetone and embedded without thawing in Lowicryl K4M for electron microscopy. Others were processed by traditional transmission electron microscopy methods. To obtain maximum resolution, the electron micrographs were photographically printed as negatives and image-enhanced by digitisation using a Polaroid Sprint Scan 45 and laser printer. In both optical and cryopreparations of juvenile and adult dentine, mineral microspheres up to 1 microm in diameter, were present in the dentinal tubules and peritubular dentine. Within these objects, the mineral was primarily in the form of sinuous electron dense filaments, 5 nm thick, which had a characteristic periodicity. In these preparations needle-like and plate-like structures were rare. In contrast, after traditional transmission electron microscopy preparation although similar filamentous structures remained, the mineral more generally had the familiar form of needles measuring approximately 50 nm in the long axis. The cryopreserved calcified filaments were apparently particularly densely distributed in the intertubular dentine where their parallel ladder-like arrays often formed highly orientated struts and stays. It was concluded that early dentine mineral has the form of filamentous microspheres and as in bone (and other calcifying tissues and cells) has no specific association with collagen. It was also concluded that these structures compact and deform with maturity into a sub-structural framework which may relate to powerful biomechanical forces transmitted through the tissue. Needle- or plate-like mineral is probably rare in vivo in dentine, only becoming commonplace after extensive chemical processing.

Complete DNA sequence of a serogroup A strain of Neisseria meningitidis Z2491

Neisseria meningitidis causes bacterial meningitis and is therefore responsible for considerable morbidity and mortality in both the developed and the developing world. Meningococci are opportunistic pathogens that colonize the nasopharynges and oropharynges of asymptomatic carriers. For reasons that are still mostly unknown, they occasionally gain access to the blood, and subsequently to the cerebrospinal fluid, to cause septicaemia and meningitis. N. meningitidis strains are divided into a number of serogroups on the basis of the immunochemistry of their capsular polysaccharides; serogroup A strains are responsible for major epidemics and pandemics of meningococcal disease, and therefore most of the morbidity and mortality associated with this disease. Here we have determined the complete genome sequence of a serogroup A strain of Neisseria meningitidis, Z2491. The sequence is 2,184,406 base pairs in length, with an overall G+C content of 51.8%, and contains 2,121 predicted coding sequences. The most notable feature of the genome is the presence of many hundreds of repetitive elements, ranging from short repeats, positioned either singly or in large multiple arrays, to insertion sequences and gene duplications of one kilobase or more. Many of these repeats appear to be involved in genome fluidity and antigenic variation in this important human pathogen.

The genome sequence of the food-borne pathogen Campylobacter jejuni reveals hypervariable sequences

Campylobacter jejuni, from the delta-epsilon group of proteobacteria, is a microaerophilic, Gram-negative, flagellate, spiral bacterium-properties it shares with the related gastric pathogen Helicobacter pylori. It is the leading cause of bacterial food-borne diarrhoeal disease throughout the world. In addition, infection with C. jejuni is the most frequent antecedent to a form of neuromuscular paralysis known as Guillain-Barré syndrome. Here we report the genome sequence of C. jejuni NCTC11168. C. jejuni has a circular chromosome of 1,641,481 base pairs (30.6% G+C) which is predicted to encode 1,654 proteins and 54 stable RNA species. The genome is unusual in that there are virtually no insertion sequences or phage-associated sequences and very few repeat sequences. One of the most striking findings in the genome was the presence of hypervariable sequences. These short homopolymeric runs of nucleotides were commonly found in genes encoding the biosynthesis or modification of surface structures, or in closely linked genes of unknown function. The apparently high rate of variation of these homopolymeric tracts may be important in the survival strategy of C. jejuni.