The sleep, circadian, and cognitive performance consequences of watchkeeping schedules in submariners: A scoping review

Watchkeeping schedules are essential for maintaining submarine operations, but come with human risk factors including, disrupted sleep, circadian misalignment, and cognitive deficits. There is now an emerging literature examining the strengths and weaknesses of submarine watchkeeping schedules trialled in the field and under simulated laboratory conditions. The aim of this scoping review was to summarise this literature. A systematic search of peer-reviewed journal articles and industry reports listed in MEDLINE, PsychINFO, PubMed, Scopus, Embase and Google Scholar undertaken in May 2023 returned 7298 papers. Following screening procedures, 13 studies were identified for inclusion. The findings revealed that sleep was sufficiently preserved regardless of watchkeeping schedule (total sleep time = 5.46-7.89 h), circadian misalignment was greater for non-24 h schedules, and longer off-watch periods were associated with better cognitive performance. Taken together, when comparing between watchkeeping schedules, the present findings suggest that the 4 h-on/8 h-off and 8 h-on/16 h-off schedules may be a good compromise when balancing human risk factors and operational demands. However, submarines are complex and challenging environments to study and there is a need to expand the literature. More research comparing watchkeeping schedules is needed. Future studies should focus on cognitive performance measures, such as problem-solving, prioritisation and executive decision-making to address present shortcomings, and an examination of sleep and circadian countermeasures to assist with adaptation either initiated pre-deployment or by modifying the submarine environment itself should be considered.

The effect of time on task, sleep deprivation, and time of day on simulated driving performance

Sleep deprivation and time of day have been shown to play a critical role in decreasing ability to sustain attention, such as when driving long distances. However, a gap in the literature exists regarding external factors, such as workload. One way to examine workload is via modulating time on task. This study investigated the combined effect of sleep deprivation, time of day, and time on task as a workload factor on driving performance. Twenty-one participants (18–34 years, 10 females) underwent 62 h of sleep deprivation within a controlled laboratory environment. Participants received an 8-h baseline and 9.5-h recovery sleep. Every 8 h, participants completed a Psychomotor Vigilance Task (PVT), Karolinska Sleepiness Scale (KSS), 30-min monotonous driving task and NASA-Task Load Index (TLX). Driving variables examined were lane deviation, number of crashes, speed deviation and time outside the safe zone. Workload was measured by comparing two 15-min loops of the driving track. A mixed model ANOVA revealed significant main effects of day and time of day on all driving performance measures (p < .001). There was a significant main effect of workload on lane deviation (p < .05), indicating that a longer time on task resulted in greater lane deviation. A significant main effect of day (p < .001) but not time of day for the NASA-TLX, PVT and KSS was found. Time on task has a significant further impact on driving performance and should be considered alongside sleep deprivation and time of day when implementing strategies for long-distance driving.

Time-of-day and days-on-shift predict increased fatigue over two-week offshore day-shifts

OBJECTIVES

The purpose of this study was to investigate the accumulation of fatigue over a two-week offshore period. In particular, the effects of (1) time-of-day and days-on-shift as well as (2) acute and chronic sleep loss on the rate at which fatigue accumulates were investigated.

METHODS

42 day-shift offshore workers were examined. Fatigue was measured using pre- and post-shift scores on the Karolinska Sleepiness Scale (KSS). Total sleep time was measured using actigraphy (Motionwatch8, Camntech). Data was analyzed using a linear mixed model analyses.

RESULTS

Average sleep loss per night was 92 min (95%CI: 89.6-94.0; p < .001). Mean cumulative sleep loss across the study was 21:20hrs (SD = 08:10hrs) over the 14 days. Chronic sleep loss was significantly related to a modest increase in sleepiness (KSS) across the shift (95%CI: 0.01-0.17; p = .020) and in post-shift scores (95%CI:.07-0.19; p < .001). Time-of-day (95%CI: 0.63 to -0.01; p = .042) and days-on-shift (95%CI: 0.03-0.08; p < .001) as well as their interaction (95%CI: 0.08 to -0.00; p = .027) influenced the rate at which fatigue accumulated over a two-week offshore period.

CONCLUSIONS

Pre- and post-shift fatigue accumulate in different ways over the two-week offshore period. The accumulation of post-shift fatigue scores was positively related to successive days-on-shift and chronic sleep loss. Our results suggest that prolonging offshore periods will likely result in elevated fatigue risk. Accumulating fatigue and sleep loss over two-week offshore periods should be considered in fatigue risk management plans and systems.

Using interstimulus interval to maximise sensitivity of the Psychomotor Vigilance Test to fatigue

There is some evidence that short interstimulus intervals (ISIs) on the Psychomotor Vigilance Test (PVT) are associated with longer and more varied reaction times (RTs). Preparation processes may impede RT following short ISIs, resulting in additional unexplained variance. The aims of this study were to investigate whether there is an effect of ISI on RT and errors within the PVT, and whether such an effect changes with three elements of fatigue: time of day, prior wake and time on task. Twelve male participants completed 49 PVTs across 7× 28h periods of forced desynchrony. For analysis, RTs, reciprocal reaction times (1/RT), false starts and lapse responses within each 10min session were assigned to a 1-s ISI group, a 2-min time of task group, a 2.5-h PW level and a 60° phase of the circadian rhythm of core body temperature (as a measure of time of day). Responses following short ISIs (2-5s) were significantly slower and more varied than responses following longer ISIs (5-10s). The likelihood of a lapse was also higher for short ISIs, while the probability of a false start increased as a function of ISI. These effects were independent of the influences of time of day, prior wake and time on task. Hence, mixed model ANOVAs comprising only long ISIs (5-10s) contained stronger effect sizes for fatigue than a model of all ISIs (2-10s). Including an ISI variable in a model improved the model fit and explained more variance associated with fatigue. Short ISIs resulted in long RTs both in the presence and absence of fatigue, possibly due to preparation processes or ISI conditioning. Hence, omitting short ISI trials from RT means or including an ISI variable in analysis can reduce unwanted variance in PVT data, improving the sensitivity of the PVT to fatigue.

The efficacy of objective and subjective predictors of driving performance during sleep restriction and circadian misalignment

Fatigue is a significant contributor to motor-vehicle accidents and fatalities. Shift workers are particularly susceptible to fatigue-related risks as they are often sleep-restricted and required to commute around the clock. Simple assays of performance could provide useful indications of risk in fatigue management, but their effectiveness may be influenced by changes in their sensitivity to sleep loss across the day. The aim of this study was to evaluate the sensitivity of several neurobehavioral and subjective tasks to sleep restriction (SR) at different circadian phases and their efficacy as predictors of performance during a simulated driving task. Thirty-two volunteers (M±SD; 22.8±2.9 years) were time-isolated for 13-days and participated in one of two 14-h forced desynchrony protocols with sleep opportunities equivalent to 8h/24h (control) or 4h/24h (SR). At regular intervals during wake periods, participants completed a simulated driving task, several neurobehavioral tasks, including the psychomotor vigilance task (PVT), and subjective ratings, including a self-assessment measure of ability to perform. Scores transformed into standardized units relative to baseline were folded into circadian phase bins based on core body temperature. Sleep dose and circadian phase effect sizes were derived via mixed models analyses. Predictors of driving were identified with regressions. Performance was most sensitive to sleep restriction around the circadian nadir. The effects of sleep restriction around the circadian nadir were larger for simulated driving and neurobehavioral tasks than for subjective ratings. Tasks did not significantly predict driving performance during the control condition or around the acrophase during the SR condition. The PVT and self-assessed ability were the best predictors of simulated driving across circadian phases during SR. These results show that simple performance measures and self-monitoring explain a large proportion of the variance in driving when fatigue-risk is high.

Daily Rhythms of Hunger and Satiety in Healthy Men during One Week of Sleep Restriction and Circadian Misalignment

The impact of sleep restriction on the endogenous circadian rhythms of hunger and satiety were examined in 28 healthy young men. Participants were scheduled to 2 × 24-h days of baseline followed by 8 × 28-h days of forced desynchrony during which sleep was either moderately restricted (equivalent to 6 h in bed/24 h; n = 14) or severely restricted (equivalent to 4 h in bed/24 h; n = 14). Self-reported hunger and satisfaction were assessed every 2.5 h during wake periods using visual analogue scales. Participants were served standardised meals and snacks at regular intervals and were not permitted to eat ad libitum. Core body temperature was continuously recorded with rectal thermistors to determine circadian phase. Both hunger and satiety exhibited a marked endogenous circadian rhythm. Hunger was highest, and satiety was lowest, in the biological evening (i.e., ~17:00–21:00 h) whereas hunger was lowest, and satiety was highest in the biological night (i.e., 01:00–05:00 h). The results are consistent with expectations based on previous reports and may explain in some part the decrease in appetite that is commonly reported by individuals who are required to work at night. Interestingly, the endogenous rhythms of hunger and satiety do not appear to be altered by severe—as compared to moderate—sleep restriction.

Time-of-day mediates the influences of extended wake and sleep restriction on simulated driving

Although a nonlinear time-of-day and prior wake interaction on performance has been well documented, two recent studies have aimed to incorporate the influences of sleep restriction into this paradigm. Through the use of sleep-restricted forced desynchrony protocols, both studies reported a time-of-day × sleep restriction interaction, as well as a time-of-day × prior wake × sleep dose three-way interaction. The current study aimed to investigate these interactions on simulated driving performance, a more complex task with ecological validity for the problem of fatigued driving. The driving performance of 41 male participants (mean ± SD: 22.8 ±2.2 yrs) was assessed on a 10-min simulated driving task with the standard deviation of lateral position (SDLAT) measured. Using a between-group design, participants were subjected to either a control condition of 9.33 h of sleep/18.66 h of wake, a moderate sleep-restriction (SR) condition of 7 h of sleep/21 h of wake, or a severe SR condition of 4.66 h of sleep/23.33 h of wake. In each condition, participants were tested at 2.5-h intervals after waking across 7 × 28-h d of forced desynchrony. Driving sessions occurred at nine doses of prior wake, within six divisions of the circadian cycle based on core body temperature (CBT). Mixed-models analyses of variance (ANOVAs) revealed significant main effects of time-of-day, prior wake, sleep debt, and sleep dose on SDLAT. Additionally, significant two-way interactions of time-of-day × prior wake and time-of-day × sleep debt, as well as significant three-way interactions of time-of-day × prior wake × sleep debt and time-of-day × sleep debt × sleep dose were observed. Although limitations such as the presence of practice effects and large standard errors are noted, the study concludes with three findings. The main effects demonstrate that extending wake, reducing sleep, and driving at poor times of day all significantly impair driving performance at an individual level. In addition to this, combining either extended wake or a sleep debt with the early morning hours greatly decreases driving performance. Finally, operating under the influence of a reduced sleep dose can greatly decrease performance at all times of the day.

Simulated driving under the influence of extended wake, time of day and sleep restriction

Around a fifth of all road accidents can be attributed to fatigued drivers. Previous studies indicate that driving performance is influenced by time of day and decreases with sustained wakefulness. However, these influences occur naturally in unison, confounding their effects. Typically, when people drive at a poor time of day and with extended wake, their sleep is also restricted. Hence, the aim of the current study was to determine the independent effects of prior wake and time of day on driving performance under conditions of sleep restriction. The driving performance of fourteen male participants (21.8 ± 3.8 years, mean ± SD) was assessed during a 10 min simulated driving task with speed/lane mean, variability and violations (speeding and crashes) measured. Participants were tested at 2.5h intervals after waking, across 7 × 28 h days with a sleep:wake ratio of 1:5. By forced desynchrony each driving session occurred at 9 doses of prior wake and within 6 divisions of the circadian cycle based on core body temperature. A mixed models ANOVA revealed significant main effects of circadian phase, prior wake and sleep debt on lane violations. In addition, three significant two-way interactions (circadian phase × prior wake, prior wake × sleep debt, sleep debt × circadian phase) and one three-way interaction (circadian × prior wake × sleep debt) were identified. The presence of the large interaction effects shows that the influence of each factor is largely dependent on the magnitude of the other factors. For example, the presence of the time of day influence on driving performance is dependent on the length of prior wake or the presence of sleep debt. The findings suggest that people are able to undertake a low-difficulty simulated drive safely, at least for a short period, during their circadian nadir provided that they have had sufficient sleep and have not been awake too long.

Sleep, wake and phase dependent changes in neurobehavioral function under forced desynchrony

STUDY OBJECTIVES

The homeostatic-circadian regulation of neurobehavioral functioning is not well understood in that the role of sleep dose in relation to prior wake and circadian phase remains largely unexplored. The aim of the present study was to examine the neurobehavioral impact of sleep dose at different combinations of prior wake and circadian phase.

DESIGN

A between-participant design involving 2 forced desynchrony protocols varying in sleep dose. Both protocols comprised 7 repetitions of a 28-h sleep/wake cycle. The sleep dose in a standard protocol was 9.33 h per 28-h day and 4.67 h in a sleep-restricted protocol.

SETTING

A time-isolation laboratory at the Centre for Sleep Research, the University of South Australia.

PARTICIPANTS

A total of 27 young healthy males participated in the study with 13 in the standard protocol (age 22.5 ± 2.2 y) and 14 in the sleep-restricted protocol (age 21.8 ± 3.8 y).

INTERVENTIONS

Wake periods during both protocols were approximately 4 h delayed each 28-h day relative to the circadian system, allowing performance testing at different combinations of prior wake and circadian phase. The manipulation in sleep dose between the 2 protocols, therefore, allowed the impact of sleep dose on neurobehavioral performance to be examined at various combinations of prior wake and circadian phase.

MEASUREMENTS AND RESULTS

Neurobehavioral function was assessed using the psychomotor vigilance task (PVT). There was a sleep dose × circadian phase interaction effect on PVT performance such that sleep restriction resulted in slower and more variable response times, predominantly during the biological night. This interaction was not altered by prior wakefulness, as indicated by a nonsignificant sleep dose × circadian phase × prior wake interaction.

CONCLUSIONS

The performance consequence of sleep restriction in our study was prominent during the biological night, even when the prior wake duration was short, and this performance consequence was in forms of waking state instability. This result is likely due to acute homeostatic sleep pressure remaining high despite the sleep episode.

Mismatch between subjective alertness and objective performance under sleep restriction is greatest during the biological night

Subjective alertness may provide some insight into reduced performance capacity under conditions suboptimal to neurobehavioural functioning, yet the accuracy of this insight remains unclear. We therefore investigated whether subjective alertness reflects the full extent of neurobehavioural impairment during the biological night when sleep is restricted. Twenty-seven young healthy males were assigned to a standard forced desynchrony (FD) protocol (n = 13; 9.33 h in bed/28 h day) or a sleep-restricted FD protocol (n = 14; 4.67 h in bed/28 h day). For both protocols, subjective alertness and neurobehavioural performance were measured using a visual analogue scale (VAS) and the psychomotor vigilance task (PVT), respectively; both measures were given at various combinations of prior wake and circadian phase (biological night versus biological day). Scores on both measures were standardized within individuals against their respective baseline average and standard deviation. We found that PVT performance and VAS rating deviated from their respective baseline to a similar extent during the standard protocol, yet a greater deviation was observed for PVT performance than VAS rating during the sleep-restricted protocol. The discrepancy between the two measures during the sleep-restricted protocol was particularly prominent during the biological night compared with the biological day. Thus, subjective alertness did not reflect the full extent of performance impairment when sleep was restricted, particularly during the biological night. Given that subjective alertness is often the only available information upon which performance capacity is assessed, our results suggest that sleep-restricted individuals are likely to under-estimate neurobehavioural impairment, particularly during the biological night.

Dynamics of neurobehavioral performance variability under forced desynchrony: evidence of state instability

STUDY OBJECTIVES

The state instability hypothesis posits that increasing sleep drive brings about escalating state instability in attention, making neurobehavioral performance increasingly variable. This hypothesis predicts that performance variability is a function of prior wake, circadian phase, and time on task. These predictions have been supported when wakefulness is beyond the habitual wake period. Our study aimed to test these predictions within the habitual wake period.

DESIGN

A 12-calendar-day 28-h forced desynchrony protocol consisting of 7 repetitions of a 28-h sleep/wake cycle, with two-thirds time awake and one-third time in bed. Each wake period included 7 equally spaced 1-h testing sessions.

SETTING

A time-isolation sleep laboratory.

PARTICIPANTS

Thirteen young healthy males.

INTERVENTIONS

Wake periods during the protocol were 4 h delayed each 28-h "day" relative to the circadian system, such that they were distributed across the whole circadian cycle. This allowed performance testing at different combinations of prior wake of a habitual length (i.e., < 18 h) and circadian phase.

MEASUREMENTS AND RESULTS

Performance variability was indexed by standard deviation of response times within a 10-min psychomotor vigilance task. We found that response times became more variable with increasing wakefulness and towards circadian nadir, i.e., when sleep drive was increasing. These changes in response time variability were however not dependent on time on task, which is likely due to the modest level of sleep drive in our study.

CONCLUSIONS

The state instability hypothesis, as an explanation for the responsiveness of neurobehavioral performance to increasing sleep drive, is supported during the habitual wake period.

Percutaneous injuries of dental personnel at the University of the West Indies, School of Dentistry

AIM

To report the results of a survey of all percutaneous injuries occurring in 2003-2004 to staff and students at the dental school in Trinidad.

METHOD

Data were collected via 163 questionnaires administered to all dental surgery assistants, the current clinical students (years 3, 4 & 5), the interns, part-time and full-time academic staff.

RESULTS

A 71% response rate was obtained. The number of persons reporting one or more sharps injuries at the dental school was 42 (37%). Of these, 17 (40%) were percutaneous. Needlesticks and periodontal scaler injuries were the most common. There was no significant correlation (p>0.05) between injury and gender, age group, dominant hand or needle recapping technique. 75% of respondents described their concern of contracting a blood-borne disease from a sharps injury as "high" and 59% of the respondents followed the school's recommended protocol following the injury. 50% of the injuries among the students and interns were not reported.

CONCLUSIONS

A more rigorous programme of risk management with respect to sharps injuries needs to be designed and implemented at the school. There is also a need to improve surveillance of and reduce the underreporting of these injuries.

Considerations on the diagnosis of oral psoriasis: a case report

This paper discusses the difficulties in making a definitive diagnosis of oral psoriasis based upon clinical and histological evidence only. A young black male presented with multiple lesions showing erosions, fissures, and yellowish scales on the vermilion borders of both lips. He also had erythematous-erosive areas on the gingivae, a fissured tongue showing greyish areas on its ventral surface, whitish lesions and longitudinal sulci in the hard palate with lacelike lesions on the soft palate. Biopsies from the lower lip, gingiva and soft palate showed hyperkeratosis, spongiosis, acanthosis, and elongation of rete ridges. In addition, collections intraepithelial micro-abscesses of Munro were observed. These findings are consistent with oral psoriasis. Typical cutaneous lesions and a family history of psoriasis were absent.

Oral lichen planus. Clinical aspects and management in fifty-two Brazilian patients

This study aimed to characterize the clinical profile of patients with oral lichen planus (OLP) and to evaluate the efficacy of topical, systemic and/or intralesional corticosteroids in the management of symptomatic cases. Fifty-two patients with OLP, 33 females and 19 males, aged from 17 to 75 years (mean 49.7 years) were studied. Information regarding the clinical forms, sites of involvement, patients' medical history and habits were recorded. Diagnosis of OLP was made using clinical criteria alone in 32 cases, while biopsy examination was required in the remaining 20. Symptomatic lesions were seen in 29 patients, who were treated with corticosteroid. Asymptomatic cases (23) were only clinically monitored. The forms of OLP found in this study were reticular (47%), atrophic (24%), erosive (21%) and plaque-like (8%). The buccal mucosa was the site predominantly affected. Systemic diseases were found in 17 patients (seven diabetic and ten with hypertension) but these data lacked statistical significance (p > 0.05) when compared with a control group of age and gender matched patients without any type of mucocutaneous disease. A habit of tobacco and/or alcohol use was reported by 11.5% of the patients, most of them with the reticular form of the disease. Topical corticosteroid therapy alone was effective in producing relief of symptoms in 18 of the 29 patients, although some relapses occurred after discontinuation. For lesions non-responsive to topical treatment, intralesional injection and/or short-term use of systemic corticosteroids were used.

Oral lichen planus. Clinical aspects and management in fifty-two Brazilian patients

This study aimed to characterize the clinical profile of patients with oral lichen planus (OLP) and to evaluate the efficacy of topical, systemic and/or intralesional corticosteroids in the management of symptomatic cases. Fifty-two patients with OLP, 33 females and 19 males, aged from 17 to 75 years (mean 49.7 years) were studied. Information regarding the clinical forms, sites of involvement, patients' medical history and habits were recorded. Diagnosis of OLP was made using clinical criteria alone in 32 cases, while biopsy examination was required in the remaining 20. Symptomatic lesions were seen in 29 patients, who were treated with corticosteroid. Asymptomatic cases (23) were only clinically monitored. The forms of OLP found in this study were reticular (47%), atrophic (24%), erosive (21%) and plaque-like (8%). The buccal mucosa was the site predominantly affected. Systemic diseases were found in 17 patients (seven diabetic and ten with hypertension) but these data lacked statistical significance (p > 0.05) when compared with a control group of age and gender matched patients without any type of mucocutaneous disease. A habit of tobacco and/or alcohol use was reported by 11.5% of the patients, most of them with the reticular form of the disease. Topical corticosteroid therapy alone was effective in producing relief of symptoms in 18 of the 29 patients, although some relapses occurred after discontinuation. For lesions non-responsive to topical treatment, intralesional injection and/or short-term use of systemic corticosteroids were used.

Reproduction and recruitment in perennial colonies of the introduced wasp Vespula germanica

We investigated the genetic structure of perennial colonies of the yellowjacket wasp (Vespula germanica) in its introduced range in Australia and New Zealand. The nuclear genotypes of 712 gynes from 21 colonies, 147 workers from 5 colonies, and 81 males from 4 colonies were assayed at three polymorphic microsatellite loci. The mitochondrial haplotypes of all wasps also were determined for a 450-bp region of the mtDNA using double-stranded conformational polymorphism (DSCP) analysis. We found that multiple reproductives were needed to explain the genotypes of gynes, workers, and males in 7 of 21, 2 of 5, and 2 of 4 colonies, respectively, and that nestmate relatedness of these three castes equaled 0.42, 0.16, and 0.22, respectively. The mitochondrial data revealed that all individuals shared the same mtDNA haplotype in 20 of the 21 colonies. However, in one colony, gynes and workers displayed multiple mtDNA haplotypes, indicating that nonnestmate recruitment had occurred. Overall the genetic structure within the majority of perennial colonies conformed to expectations based on the biology of V. germanica and kin selection theory for polygyne colonies; multiple reproductives successfully produced offspring and were recruited into their natal nests, thereby maintaining relatively high relatedness between interacting individuals.

Hierarchical genetic structure of the introduced wasp Vespula germanica in Australia

The wasp Vespula germanica is a highly successful invasive pest. This study examined the population genetic structure of V. germanica in its introduced range in Australia. We sampled 1320 workers and 376 males from 141 nests obtained from three widely separated geographical areas on the Australian mainland and one on the island of Tasmania. The genotypes of all wasps were assayed at three polymorphic DNA microsatellite markers. Our analyses uncovered significant allelic differentiation among all four V. germanica populations. Pairwise estimates of genetic divergence between populations agreed with the results of a model-based clustering algorithm which indicated that the Tasmanian population was particularly distinct from the other populations. Within-population analyses revealed that genetic similarity declined with spatial distance, indicating that wasps from nests separated by more than approximately 25 km belonged to separate mating pools. We suggest that the observed genetic patterns resulted from frequent bottlenecks experienced by the V. germanica populations during their colonization of Australia.

The permeability of human dentine in vitro and in vivo

Experiments in cats have shown that Evans blue dye diffuses at a greater rate into dentine in recently extracted teeth than in vivo. These experiments have now been repeated in man and similar results were obtained except that, after applications in vivo, visible concentrations of the dye were present in the dentine, and in a few cases, even in the pulp. It is concluded that, as in the cat, the diffusion in vivo was impaired by outward flow of fluid in the dentinal tubules but the mean velocity of flow in the human dentine was less than that in the cat.

Insects as teaching tools in primary and secondary education

Insects offer a vast array of teaching opportunities for precollege students. Here we address the basics teachers need in order to use insects successfully in their curricula. We identify exemplary resources in the printed North American literature and point out potentially productive places for teachers and students to search for ideas and materials. We review the roles of entomology in the educational framework, highlight favorite classroom arthropods and less well-known examples, and guide readers to entomological resources. Tips to help teachers identify, rear, and maintain classroom insects and find equipment and supplies are included. The review concludes with a plea for greater classroom and curricular involvement by those in the entomological profession.

Chronic lymphocytic leukaemia with gingival and palatal deposits

The oral features of a patient with notable maxillary and mandibular gingival enlargement secondary to leukaemic infiltration in chronic lymphocyte leukaemia are presented.

Working patterns of male and female dentists in the UK

A random selection of male (250) and female (250) dentists in the Dentists Register 1992 were sent a postal self-administered questionnaire to determine their working patterns, places of work and whether or not they had children of school age or younger. There was also space for free comment. Responses from 75% of males and 81% of females were received. Results show that 79% of males, compared with 46% of females, work in full-time dentistry, chiefly in general dental practice. Family commitments were the principal reason for 30% of female dentists working part-time. A small number (14%) of male dentists work in a second career alongside part-time dentistry. As a female dentist's family becomes older and less dependent so the number of sessions worked increases. Overall, female dentists felt well suited and satisfied with their chosen profession. A small, but worrying group (4%) of male full-time general dental practitioners were very dissatisfied with dentistry as a career and showed clear signs of severe psychological stress expressed in the style and nature of free comments made.

The efficacy of management of acute dental pain

The effectiveness of pain relieving treatments given for acute dental pain has been evaluated after 24 hours in 172 patients who presented to a dental hospital emergency department. Patients were contacted by telephone the day after attendance and graded their pain on a scale from 1 (no pain) to 5 (pain much worse). The mean pain scores for each diagnosis of cause of pain were calculated and related to the treatment given. Some 76% of patients were in pain due to the ravages of dental caries of periodontal disease. Overall, 87% received marked or total pain relief and this appeared to depend upon decompression of inflamed tissue. Oral administration of antimicrobial drugs alone produced little or no pain relief within 24 hours and anti-inflammatory analgesics offer poor pain control in these circumstances.

Recent trends in university entry for dentistry in the UK

The pattern of university applications has been related to dental school application rates between 1985 to 1991. The academic standard of GCE 'A' level attainment acceptable to each school has also been related to the number of places available and number of places filled. Whilst the total number of university applications has increased over the period, dental applications have decreased, with a lower proportion of male applicants being noticeable. Some schools had lower application rates than others. There appeared to be a tendency for schools which had previously accepted slightly lower 'A' level standards for entry to receive a larger number of applicants. Some schools showed evidence of accepting lower 'A' level standards of entry presumably to meet the financial need to fill all available places.

Pulse oximetry during minor oral surgery with and without intravenous sedation

This study investigated the levels of oxygen saturation and pulse rates of patients undergoing minor oral surgery under local analgesia, with (20 patients) or without (20 patients) intravenous sedation with midazolam. The results indicated that a statistically significant fall in arterial blood oxygenation of 1% to 2%, as measured by pulse oximetry, followed midazolam administration; however, this was physiologically insignificant. Both groups showed a similar postoperative small fall in oxygen saturation. Transient episodes (24 to 36 seconds) of physiologically significant mild hypoxia occurred during breath holding, but this condition was readily corrected by encouraging patients to breathe deeply. Midazolam had a small but significant calming effect on the higher preoperative pulse rates exhibited by anxious patients, but this effect was not sustained during the operating period. Both sedated and unsedated patients showed episodes of tachycardia that could have significance for patients with cardiac disease.

Cardiopulmonary resuscitation skills of dental personnel

This study assessed the cardiopulmonary resuscitation (CPR) skills of 25 dental personnel. Theory was tested by multiple choice questionnaire (MCQ) and practical skills assessed using a recording Resusci-Anne manikin. The assessment was based upon the recommendations of the Resuscitation Council of the UK. Seven of the 16 dental students and six of the nine house officers tested passed the MCQ examination. All failed the practical assessment. It is concluded that more emphasis should be placed upon CPR instruction in undergraduate dental courses and that regular update courses are advisable to maintain CPR skill.

A study of the comparative efficacy of four common analgesics in the control of postsurgical dental pain

Four common oral analgesics were tested in a single-blind trial to determine their relative efficacy in the management of postsurgical pain in 103 patients who had their impacted third molars surgically removed under general anesthesia. The analgesics tested were acetylsalicylic acid (26 patients), ibuprofen (26 patients), a paracetamol/codeine/caffeine combination (Solpadeine) (25 patients), and dihydrocodeine (26 patients). The paracetamol/codeine/caffeine combination, ibuprofen, and acetylsalicylic acid preparations produced equally effective analgesia. Dihydrocodeine was found to be a poor analgesic in this pain model. There were no adverse reactions to any of the preparations.

Where are we going?

As medicine and dentistry have grown in complexity, so has the nature of the relationship between the two sciences. With increasing financial pressures and declining in-takes to dental schools, Robin Matthews argues that both disciplines would gain through a closer, more coordinated liaison.

Roxithromycin as a possible agent for prophylaxis of endocarditis: a study in normal volunteers

A single dose of roxithromycin, 300 mg, was taken by six healthy male volunteers on three occasions at consecutive weekly intervals. It was well tolerated. On the first two occasions, roxithromycin was assayed in serum samples taken at intervals up to 8 h after the administration. The mean peak concentration at 1 h was 3.0 mg/l (range 0.3-7.3). The serum samples from the volunteers showed variable bactericidal activity against a strain of Streptococcus sanguis isolated from a case of bacterial endocarditis. Roxithromycin was not detected in saliva or gingival fluid. Smooth surface plaque samples taken at intervals were investigated for the emergence of streptococci resistant to roxithromycin at 2 and 8 mg/l. Initially two volunteers had small number of roxithromycin-resistant streptococci. At the end of the study all six volunteers had resistant streptococci detectable in their plaque samples and these accounted for 100% of the streptococci in two volunteers. The most resistant isolates (in several cases with MIC greater than 64 mg/l) were Str. sanguis or Str. mitior; individual volunteers tended to yield the same strain on consecutive samplings.

Nesting Biology and Taxonomy of Arpactophilus-Mimi, a New Species of Social Sphecid (Hymenoptera, Sphecidae) From Northern Australia

Arpactophilus mimi, Naumann, sp. nov., is described from Kakadu National Park, N.T. and its biology is outlined. A. mimi nests in abandoned cells of mud-dauber wasps in sandstone overhangs. Its nests are lined heavily with silk and contain 1-15 cells and 1-10 adult wasps (1-7 females, 0-3 males). On average nests contain 5.2 cells and 2.75 adult females. Prey (immature Psyllidae and Tingidae) are supplied progressively. Nests are parasitised by a species of megalyrid wasp, but incidence of parasitism is low. Nest defense is both physical (entrance guard always present) and chemical (citrus odour from heads of both sexes). Females from a single nest could be ranked on the basis of relative ovarian development, suggesting that more than one female oviposits. Females apparently cooperate in brood care and offspring in a nest develop asynchronously. The biology of A. mimi is compared to that of Microstigmus comes Krombein, the most socially advanced sphecid known, and selective pressures that may have acted to promote female cooperation in the two genera are discussed. For A. mimi the lack of available nest sites could be an important factor restricting the ability of offspring to disperse and establish nests.

Clinical evaluation of benzydamine, chlorhexidine, and placebo mouthwashes in the management of recurrent aphthous stomatitis

Eighteen patients with minor recurrent aphthous stomatitis were given alcoholic benzydamine hydrochloride, aqueous chlorhexidine, or a benzydamine-free placebo mouthwash in random order. Each patient used each preparation for a 3-month period. Ulcer diaries were marked at the same time each week during the 9-month test period. Records were made of the number, size, sites, and pain severity of any ulcers present. Statistical analysis of the results showed no significant differences between any of the treatments tested. Stinging of the oral mucosa was the only consistent side effects noted by nine patients using benzydamine, nine patients using placebo, and three patients using chlorhexidine. Eight patients stated a personal preference for benzydamine because of the transient local anesthetic effect of benzydamine, which gave pain relief.