Post-brushing rinsing for the control of dental caries: exploration of the available evidence to establish what advice we should give our patients.

Post-tooth brushing rinsing behaviours have the potential to either reduce or enhance the effectiveness of fluoride toothpaste and show wide variation in the general population. There is a lack of high-quality evidence to support definitive guidance in this area. However, the currently available international guidelines provide consistent recommendations despite the limited evidence. To explore the available evidence base and recommendations on optimal post-brushing rinsing behaviour relating to the use of both water and mouth rinses, a meeting was held between the authors and other experts. This paper reports the consensus views of those present at the meeting concerning what advice we should give our patients. A full list of meeting attendees is provided at the end of this article.

Hospital-based epidemiology: a strategy for 'dealing with Clostridium difficile'.

Clostridium difficile-associated diarrhoea (CDAD) remains a major infection control problem. Uncertainty remains over methods of diagnosis and definitions for ascertaining provenance of cases. We undertook a prospective epidemiological study to better ascertain local epidemiology of 275 new cases (general practitioner and hospital) diagnosed in a large teaching hospital in the UK. The highest incidence of cases was found in haematology and critical care and a surprisingly high proportion, 29%, of hospital cases occurred in those aged <65 years. Fifty-five cases were diagnosed within 48h of admission. Of these, those defined as 'community-acquired' varied between 9 and 25 according to various proposed definitions relating to acquisition and onset of diarrhoea. Of 48 community-onset cases, this number varied between 19 and 25, the variability making comparisons between National Health Service (NHS) trusts potentially inaccurate. Cases were followed for 90 days after diagnosis and all cause mortality data obtained. Of 227 cases diagnosed in hospital, 56 (25%) died within 30 days, 29% of whom were aged <65 years. Death certification data were available in 86% of these cases. C. difficile was recorded on 15 (31%) certificates and as a primary cause (1a or 1b) in 8 (17%) cases. Our study shows the value of local epidemiology for planning infection prevention and control strategies within an NHS trust and for contributing to the evidence base for national targets and policies.

Effects of flossing and rinsing with a fluoridated mouthwash after brushing with a fluoridated toothpaste on salivary fluoride clearance.

The aims of this study were to test the hypothesis that flossing after brushing with a fluoridated toothpaste may lower salivary fluoride (F), and to evaluate the consequence of subsequent F mouthwash use. Twenty adults used 3 oral hygiene regimes in a randomised order: A, brushing with an NaF toothpaste; B, as A but followed by professional flossing; C, as B followed by rinsing with an NaF mouthwash. Saliva samples were collected up to 120 min after each regime and analysed for F. The mean area under the clearance curve value for regime C was statistically significantly greater than the corresponding values for A and B (p < 0.0001), which differed little. The regime that included the mouthwash may provide better anticaries protection.

Effect of rinsing with mouthwashes after brushing with a fluoridated toothpaste on salivary fluoride concentration.

The aim of the study was to determine whether rinsing with a mouthwash after brushing with a fluoridated toothpaste affected oral fluoride (F) retention and clearance compared with an oral hygiene regime without mouthwash. In this supervised, single-blind study, 3 regimes were compared: (A) brushing for 1 min with 1 g of 1,450 microg F/g NaF toothpaste followed by rinsing for 5 s with 10 ml water; (B) as A but followed by rinsing for 30 s with 20 ml of 100 mg F/l NaF mouthwash, and (C) as B but rinsing for 30 s with a non-fluoridated mouthwash. Twenty-three adults applied each treatment once in a randomised order, separated by 1-week washout periods, and used a non-fluoridated toothpaste at home prior to and during the study. Whole saliva samples (2 ml), collected before each treatment commenced and 10, 20, 30, 60, 90 and 120 min afterwards, were subsequently analysed for fluoride by ion-specific electrode. The mean (SD) back-transformed log (area under salivary F clearance curve) values were: A = 2.36 (+3.37, -1.39), B = 2.54 (+2.72, -1.31) and C = 1.19 (+1.10, -0.57) mmol F/l x min, respectively. The values for regimes A and B were statistically significantly greater than that for regime C (p < 0.001; paired t test). These findings suggest that use of a non-F mouthwash after toothbrushing with a F toothpaste may reduce the anticaries protection provided by toothbrushing with a F toothpaste alone. The use of a mouthwash with at least 100 mg F/l should minimise this risk.

Evolution of sex-biased maternal effects in birds. IV. Intra-ovarian growth dynamics can link sex determination and sex-specific acquisition of resources.

The evolutionary importance of maternal effects is determined by the interplay of maternal adaptations and strategies, offspring susceptibility to these strategies, and the similarity of selection pressures between the two generations. Interaction among these components, especially in species where males and females differ in the costs and requirements of growth, limits inference about the evolution of maternal strategies from their expression in the offspring phenotype alone. As an alternative approach, we examine divergence in the proximate mechanisms underlying maternal effects across three house finch populations with contrasting patterns of sex allocation: an ancestral population that shows no sex-biased ovulation, and two recently established populations at the northern and southern boundaries of the species range that have opposite sequences of ovulation of male and female eggs. For each population, we examined how oocyte acquisition of hormones, carotenoids and vitamins was affected by oocyte growth and overlap with the same and opposite sexes. Our results suggest that sex-specific acquisition of maternal resources and sex determination of oocytes are linked in this system. We report that acquisition of testosterone by oocytes that become males was not related to growth duration, but instead covaried with temporal exposure to steroids and overlap with other male oocytes. In female oocytes, testosterone acquisition increased with the duration of growth and overlap with male oocytes, but decreased with overlap with female oocytes. By contrast, acquisition of carotenoids and vitamins was mostly determined by organism-wide partitioning among oocytes and oocyte-specific patterns of testosterone accumulation, and these effects did not differ between the sexes. These results provide important insights into three unresolved phenomena in the evolution of maternal effects - (i) the evolution of sex-specific maternal allocation in species with simultaneously developing neonates of both sexes; (ii) the link between sex determination and sex-specific acquisition of maternal products; and (iii) the evolution of context-dependent modulation of maternal effects.

A wearable reflectance pulse oximeter for remote physiological monitoring.

To save life, casualty care requires that trauma injuries are accurately and expeditiously assessed in the field. This paper describes the initial bench testing of a wireless wearable pulse oximeter developed based on a small forehead mounted sensor. The battery operated device employs a lightweight optical reflectance sensor and incorporates an annular photodetector to reduce power consumption. The system also has short range wireless communication capabilities to transfer arterial oxygen saturation (SpO(2)), heart rate (HR), body acceleration, and posture information to a PDA. It has the potential for use in combat casualty care, such as for remote triage, and by first responders, such as firefighters.

Context-dependent sexual advertisement: plasticity in development of sexual ornamentation throughout the lifetime of a passerine bird.

Male investment into sexual ornamentation is a reproductive decision that depends on the context of breeding and life history state. In turn, selection for state- and context-specific expression of sexual ornamentation should favour the evolution of developmental pathways that enable the flexible allocation of resources into sexual ornamentation. We studied lifelong variation in the expression and condition-dependence of a sexual ornament in relation to age and the context of breeding in male house finches (Carpodacus mexicanus)--a species that develops a new sexual ornament once a year after breeding. Throughout males' lifetime, the elaboration of ornamentation and the allocation of resources to the development of sexual ornamentation depended strongly on pairing status in the preceding breeding season--males that were single invested more resources into sexual ornamentation and changed ornamentation more than males that were paired. During the initial (post-juvenile) moult, the expression of ornamentation was closely dependent on individual condition, however the condition-dependence of ornamentation sharply decreased throughout a male's lifetime and in older males expression of sexual ornamentation was largely independent of condition during moult. Selection for early breeding favoured greater ornamentation in males that were single in the preceding seasons and the strength of this selection increased with age. On the contrary, the strength of selection on sexual ornamentation decreased with age in males that were paired in the preceding breeding season. Our results reveal strong context-dependency in investment into sexual ornamentation as well as a high flexibility in the development of sexual ornamentation throughout a male's life.

A condition dependent link between testosterone and disease resistance in the house finch.

Testosterone has recently been proposed as a link between male quality and health and the expression of sexual traits. We investigated the relationship between testosterone and measures of the individual condition and health of males in a natural population of house finches (Carpodacus mexicanus). We also conducted a captive experiment in order to test for the effects of testosterone on resistance to coccidia, which is a common parasite of house finches. Free-living males in better condition had higher testosterone levels and lower corticosterone levels than free-living males in poor condition. In our captive experiment, increased testosterone accelerated the rate of coccidial infection as compared with sham-implanted or gonadectomized males. Although the differences were not significant, free-living males infected with coccidia had lower levels of testosterone and higher levels of corticosterone than males that were not infected. Thus, experimentally elevating testosterone levels in captive males resulted in a higher percentage of infected males, while free-living males with coccidial infection had low testosterone levels. This apparent discrepancy between captive and free-living males in the association of testosterone and disease may be explained by the condition dependence of testosterone. These results suggest that the testosterone-dependent sexual traits reliably indicate male overall condition and health and, thus, females could benefit from assessing potential mates based on these traits.

Maintenance of a captive flock of house finches free of infection by Mycoplasma gallisepticum.

Since the beginning of an epidemic of conjunctivitis in wild house finches caused by Mycoplasma gallisepticum (MG), all captive colonies established by capturing free-ranging house finches from the eastern population have also either been infected at the time of capture or developed infection shortly after capture. In an attempt to avoid this infection in captive flocks being maintained for studies of the finches' behavior and ecology, we compared two different flock management strategies and were able to prevent the development of mycoplasmal conjunctivitis with one of the strategies. Single-sex flocks were built by introducing only seronegative wild-caught birds showing no clinical signs of conjunctivitis and covering their outdoor flight cages with netting to prevent interaction with other wild birds although only the female flocks were initially treated with a 6-wk course of tylosin tartrate (0.3 mg/ml). The female flocks never developed conjunctivitis although the disease did develop in the male flocks. Furthermore, serologic assessments of the healthy flock by serum plate agglutination assays for MG indicated that the females remained free of MG infection in the final 7 wk of the study, during which they were unmedicated. We conclude that any low-level MG infection not diagnosed by the initial test for seroconversion was cleared by the prolonged drug treatment.

Fluoride uptake to demineralised enamel: A comparison of sampling techniques.

Fluoride uptake is a recognised way of assessing the potential anticaries efficacy of fluoride (F) treatments. The aim of the present study was to compare an abrasion method of sampling treated enamel, based on that of Weatherell et al. [Caries Res 1985;19:97-102], with the acid-etch method of Raven et al. [Caries Res 1991;25:130-137]. Two adjacent demineralised areas were created on the polished surfaces of bovine incisors using an acid gel system. One artificial lesion from each tooth was subsequently treated for 6 h at 37 degrees C with one of two fluoridated dentifrice slurries (1 part: 3 parts water), whereas the other was treated similarly with a slurry of non-F control dentifrice. One set of treated lesions was then separated, the base of each enamel block polished until planoparallel with the demineralised surface and the lesions isolated by cutting away the adjacent sound enamel. Each block was mounted on the probe of a digital micrometer and the demineralised surface abraded with silicon carbide lapping film until sound material was reached. Abraded material was dissolved in perchloric acid and the buffered solution analysed for fluoride by ion-selective electrode. Each lesion of a second set of treated, demineralised enamel blocks was etched by 20microl acid and the resulting solutions analysed for F. Mean F uptakes [microg cm-2 (SD)] were: abrasion (n = 7/treatment); F dentifrice A = 1.39 (0.89) and B = 0.86 (0.45) relative to non-F controls = 0.11 (0.12), 0.14 (0.06), respectively; and acid-etch (n = 14/treatment); A = 1.27 (0. 49), B = 0.69 (0.23), controls = 0.12 (0.06), 0.12 (0.06), respectively. Significant differences (p<0.05) for both data sets were: A>B> control. The results show good agreement between the sampling methods and demonstrate the ability of the abrasion technique to distinguish between F treatments.

Acute bereavement services and routine referral as a mechanism to increase donation.

Efforts to develop a mechanism that improves donation rates and provides better service to patients and staff are presented in this article. The University of Nebraska Medical Center has incorporated a routine referral process into its acute bereavement services requiring representatives to respond to each in-house death to provide consistent support and management for the decedent's family and the hospital staff. Every family was offered bereavement support and the opportunity to consent to autopsy as well as to organ and tissue donation if medically appropriate. Key data related to death and consent discussions were documented, routinely reviewed, and reported to a central location. Appropriate and timely access of these data helped to modify the program and assess its need for additional education or intervention.

Effect of low levels of fluoride on calcium uptake by demineralized human enamel.

The effect of fluoride (ca. 0.1 parts/10(6)) on calcium uptake by enamel was examined under alternating remineralizing and demineralizing conditions. The remineralizing solutions contained either 0, 0.058, 0.104, or 0.138 parts/10(6) fluoride (ex NaF), while the demineralizing solutions contained no added fluoride. During the demineralization periods, calcium loss was similar for all groups. However, during the remineralizing periods, all levels of added fluoride were found to promote calcium uptake. Calcium levels taken up by the artificial lesions were sound to increase with increasing fluoride concentration in solution, and were independent of surface area of exposed enamel. In the absence of fluoride, even under conditions that are considered to be remineralizing, further demineralization took place.

A comparison of 25 G and 27 G Whitacre needles for caesarean section.

Spinal needles with a pencil-point tip and those of a finer gauge are known to be associated with a lower incidence of postdural puncture headache. This study set out to determine if fine pencil-point needles were acceptably easy to use in routine clinical practice. Two hundred and twelve women undergoing elective Caesarean section were randomly allocated to receive a subarachnoid block using either a 25 G or 27 G Whitacre needle. Factors determining ease of needle use, adequacy of block, incidence of postdural puncture headache, backache and neurological sequelae were assessed. Successful intrathecal injection was achieved in all patients in the 25 G group. Using the 27 G needle, the anaesthetist failed to reach the subarachnoid space in eight patients of which seven subsequently had a successful intrathecal injection with a larger needle. These failures were attributed to excessive needle flexibility which was the only significant difference in ease of use between the 25 G and 27 G needles. In the 25 G group, there was one severe postdural puncture headache which required an epidural blood patch and three mild headaches which resolved spontaneously. There were no postdural puncture headaches in the 27 G group. We conclude that the final choice of needle is a compromise between the ease of use and lower failure rate of the 25 G needle and the, as yet unproven, possibility of a lower incidence of postdural puncture headache with the 27 G needle.

Studies on plaque fluoride after use of F-containing dentifrices.

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

Studies on the cariostatic mechanisms of fluoride.

This paper reviews mechanisms underlying the caries-preventive effects of fluoride, with special reference to factors which govern the efficacy of topical treatments. Fluoride reduces demineralisation in several ways: by reducing bacterial acid production and acidurance; by reducing the equilibrium solubility of apatite; and by the fluoridation of apatite crystal surfaces, reducing the dissolution rate, whether or not there is reduced solubility of the bulk mineral. On available evidence, the last seems to be the most important effect. The effect depends upon the presence of sufficiently high, dissolved fluoride concentrations to maintain the surface fluoridation. The provision of dissolved fluoride is the key to successful therapy, especially topical treatments. Fluoride also promotes remineralisation even at low concentrations, thus slowing or preventing overall mineral loss. The formation of intra-oral fluoride reservoirs capable of supplying ions for a prolonged period is crucial to the success of topical treatments. Such reservoirs include calcium fluoride, formed mainly at tooth surfaces, and fluoride associated with organic components of plaque and oral soft tissues. The patterns of fluoride clearance from intraoral reservoirs are discussed. Fluoride may be present in dentifrices as the fluoride ion (F-) or as the monofluorophosphate ion (FPO3(2-)). It is concluded that the efficacy of FPO3(2-) probably depends on enzymic hydrolysis to F-. Monofluorophosphate appears to be retained less well in intra-oral fluoride reservoirs and reasons for this are discussed.

Effect of mouthwashes of variable NaF concentration but constant NaF content on oral fluoride retention.

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