bluuebunny/crossref_metadata_2025 huggingface dataset:
Skewed distributions – new outcome measures
Authors: Spencer A. John
Published: May 2006

Abstract The traditional measure of caries, the DMF index, either as prevalence or incidence of disease, has become highly positively skewed among children and young adults. Most discussion of skewed distributions has focused on the properties of statistical analyses using such data or the implications for sample sizes and subject selection in clinical trials. This paper examines the full range of epidemiologic studies, their aims and constitutive interest in order to identify the measurement problems associated with skewed DMF index data. Constitutive interests include: description; documentation; explanation and prediction; evaluation; advocacy; and, experimentation. ‘New’ outcome measures that would assist in reaching the aims and constitutive interests of the epidemiology of caries include caries severity grading, variants of prevalence, extent and severity and their combination into case definitions, and weighting of the components of the DMF index. Research questions for each area of ‘new’ outcome measures are identified as steps in the codifying of their use in the epidemiology of caries.
Does assessment of microbial composition of plaque/saliva allow for diagnosis of disease activity of individuals?
Authors: Bowden G. H.
Published: May 2006

Abstract Microbiological tests are limited in their applicability in the assessment of caries activity and in caries prediction. They can be effective in groups of persons with high or low caries experience. The reasons for the limitation of microbiological tests rests with unique characteristics of the microflora and local environments of the oral cavity, which will modify the cariogenicity of plaque in an individual. Thus, high numbers of S. mutans may be associated with the development of a lesion at a site, while a second susceptible site with high levels of this organism in the same subject will remain caries free. This paper identifies some aspects of oral bacteria which can contribute to the unique nature of the microflora associated with plaque in an individual. Firstly, the range of bacteria potentially involved in caries has widened and now includes, for example, ‘low pH’ non‐mutans streptococci. The presence of such organisms in plaque in an individual may influence early enamel demineralization. Most significantly. Streptococcus mutans, Streptococcus mitis and Actinomyces naeslundii have been shown to be comprise many distinct clones, with different distribution among subjects. Little is known of the impact of clonal diversity on caries activity but in some bacterial diseases particular clones are associated with virulence. Therefore, possession of a particular clone or clones by an individual could be related to caries activity. Also, the extent of clonal diversity may reflect the nature of the oral environment. Recent studies suggest that cells are released from biofilms during adherence and growth, i.e. the early phases of development. Thus, determination of the numbers of a given species in non‐stimulated saliva may indicate whether it is actively growing in plaque. Microbiological tests on the oral flora should perhaps be used to monitor the status of the oral cavity, after establishing a norm for the individual patient. Research on species and clonal diversity of oral bacteria among human populations; diversity and its role in the caries process; and the liberation of biofilm cells could provide data to allow better appreciation and evaluation of the results of microbiologiocal testing.
Caries prediction – state of the art
Authors: Hausen Hannu
Published: May 2006

Abstract This paper considers the question of whether, by using the currently available measures for assessing caries risk, one can identify with sufficient accuracy the high caries‐risk susceptible individuals who need individual protection to avoid having an unacceptably high number of new cavities. In addition, the outline of a typical caries prediction study is presented with an example. Finally, the accuracy of an actual caries prediction is compared with the accuracy of predicting the onset of acute myocardial infarction in order to point out the fact that the risk of any disease is difficult to assess accurately.
What do we know about how dentists make caries‐related treatment decisions?
Authors: Bader James D. , Shugars Daniel A.
Published: May 2006

Abstract A conceptual model of dentists' treatment decision‐making is discussed. The model suggests that dentists do not use a hypothetico‐deductive process for the diagnosis of caries. Rather, caries is identified through a process of pattern recognition that in most instances is inextricably linked to intervention decisions. Individual dentists have inventories of caries scripts that, when matched by a particular clinical presentation, lead to decisions to treat. The scripts comprise salient factors that are dependent on individual dentists characteristics and biases, and thus vary substantially across dentists. The scripts tend to be complex, highly visual, and difficult to describe. All of these characteristics suggest that efforts to improve dentists' caries‐related treatment decisions should acknowledge this knowledge structure and be designed to change the salient factors or interpretations of salient factors within the context of the caries script.
Can organised dental care for children be both good and cheap?
Authors: Riordan Paul J.
Published: May 2006

Abstract Children's dental services evolved from emergency, pain‐relieving and later amalgam‐based care systems of the early and middle 20th century. The pattern of occurrence of dental caries is different today and young teenagers have very few teeth affected by caries. Restoration of lesions in permanent teeth, typically on occlusal or buccal/lingual surfaces, is technically simple. Paradoxically, dental students today are expected to master a vast amount of knowledge, including information on new dental materials and techniques. New dentists who choose to provide dental care for children as a career will spend most of their days placing fissure sealants, applying topical fluorides and inserting predominantly single‐surface restorations. Because of their expensive training, new dentists will nevertheless expect high earnings, and this results in a high cost for children's dental care. The opportunity cost is other health services foregone, In developing countries where there are few dentists, they are almost not available for children at all. Costs could be reduced by reducing the number of interventions, and by reducing staff costs. Fewer interventions could be achieved by longer recall intervals: several studies and experience from places where this has been implemented indicate that this is safe and effective. Widespread delegation of operative work to appropriately trained dental hygienists or therapists would reduce staff costs. Dental therapists are better substitutes for dentists in children's care because they are trained to do most of the clinical procedures that are necessary in children's dentistry. In Western Australia and South Australia, most dental care for children is provided by dental therapists. The costs of care are much lower and the outcome, as measured by caries experience and numbers of treated patients, is equivalent to or even better than European dentist‐based services. Already, in some places, politicians and others are querying the need for organised children's dental care. Increased effectiveness will make continuation of children's dental services easier to sustain.
Extent and provision of orthodontic services for children and adolescents in Finland
Authors: Pietilä Terttu , Pietilä IIpo , Widströ Eeva , Varrela Juha , Alanen Pentti
Published: May 2006

Abstract Orthodontic services for Finnish children and adolescents up to the age of 18 in 1992 were monitored by a questionnaire sent to all municipal health centres responsible for children's dental care in Finland, and 96% responded. All health centres provided some orthodontic treatment, but the percentage of 0–18‐year‐old children receiving treatment ranged from 1% to 19%. One‐quarter of all dental visits of the 0–18‐year‐olds were in connection with orthodontics. The timing of treatment was early: the average age for starting was 9.5 years. In statistical analyses, the number of children receiving treatment was associated with the timing of treatment. At the age of 7, the most frequently used appliances were quad helix, removable appliance and orthopaedic headgear and, at the age of 13, fixed appliance and activator. Most treatments were provided by nonspecialists. The specialist expertise needed was usually purchased from an outside orthodontist by means of consultation contracts. Every fifth health centre, usually the largest, had employed one or more specialist orthodontists. The regional distribution of orthodontists was uneven, emphasizing regional variation in the delivery of orthodontic services.
Occlusal restorative decisions based on visual inspection –calibration and comparison of different methods
Authors: Lavonius Eeva , Kerosuo Eero , Kallio Pekka , Pietilä Ilpo , Mjör Ivar A.
Published: May 2006

Abstract The purpose of this in vitro study was to calibrate occlusal restorative decision‐making based on visual inspection (VI), and to compare it with visual inspection with magnifying (×1.25) lenses (VIM), and fibre‐optic transillumination (VIF). Sixty extracted human third molars mounted in plaster were examined using VI by ten dentists three times during the calibration process. After wash‐out periods, the teeth were re‐examined by the same dentists using VI, VIM and VIF. The inter‐examiner reproducibility for VI, expressed as Kappa (κ) statistics (K±SD), was 0.46±0.10 before and 0.59±0.1 1 after the calibration process and remained at the same level after the wash‐out period. Intra‐examiner reproducibility was substantially higher for VI (κ=0.68±0.15) before and after the wash‐out period. There were no significant changes in restorative treatment decisions based on VIM and VIF when compared to VI. The reproducibility between the methods was good for VI vs. VIM (κ= 0.64) and moderate for VI vs. VIF (κ= 0.56). In contrast, the inter‐examiner reproducibilities expressed as Kappa were considerably lower for VIM (κ= 0.46±i0.17) and VIF (κ=0.42±0.19). It was concluded that the inter‐examiner reproducibility can be improved with a calibration process based on a simple feedback method and that inter‐examiner variation, especially without calibration, may be as important a factor for restorative treatment decisions as the diagnostic method itself.
Prevalence of perceived symptoms of dry mouth in an adult Swedish population ‐ relation to age, sex and pharmacotherapy
Authors: Nederfors T. , Isaksson R. , Mörnstad H. , Dahlöf C.
Published: May 2006

Abstract The aim of the study was to evaluate the prevalence of subjective perception of dry mouth in an adult population and to determine the prevalence of pharmacotherapy in this population. An additional aim was to assess a possible co‐morbidity between symptoms of dry mouth and continuing pharmacotherapy. Four‐thousand‐two‐hundred persons were selected at random from the national census register of the adult population of the southern part of the province of Halland, Sweden. The sample was stratified according to age and sex, and 300 men and an equal number of women aged 20, 30, 40, 50, 60, 70 and 80, were included. A newly developed questionnaire was mailed to each individual. In addition to questions about subjective perception of dry mouth, the subjects were asked to report on present diseases and continuing pharmacotherapy. Three‐thousand‐three‐hundred and thirteen (80.5%) evaluable questionnaires were returned. The estimated prevalence of xerostomia in the population was 21.3% and 27.3% for men and women, respectively. This difference between the sexes was statistically significant. In non‐medicated subjects, women tended to report a higher prevalence of xerostomia compared with men, 18.8% vs. 14.6%, and also among medicated subjects the estimated prevalence of dry mouth was higher for women than for men, 32.5% vs. 28.4%. There was a strong association between xerostomia and increasing age and also between xerostomia and continuing pharmacotherapy. The average prevalence of dry mouth among medicated and non‐medicated subjects was 32.1% and 16.9%, respectively, the difference being statistically significant. There was also a strong association between xerostomia and the number of medications. In a logistic regression, the probability of reporting mouth dryness was significantly greater in older subjects and in women, and the probability increased with the number of medications taken. In conclusion, this epidemiological survey of an adult population has demonstrated that women, independent of age, do report a higher prevalence of xerostomia than men and that the symptom of dry mouth is strongly associated with age and pharmacotherapy. It is, however, not possible to discriminate between disease and pharmacotherapy as causal factors.
Electronic diagnosis of occlusal caries in vitro: adaptation of the technique for epidemiological purposes
Authors: Ricketts David Nigel James , Kidd Edwina Anne Maria , Wilson Ronald Frederick
Published: May 2006

Abstract Most studies on electronic diagnosis of occlusal caries have involved taking site‐specific conductance measurements. Airflow around the electronic caries monitor probe removes superficial moisture and the conductance measurement reflects the caries status of that part of the fissure beneath the probe tip. This is an appropriate technique for a clinician to use to monitor caries status, and it could be adapted for use in epidemiological studies and clinical trials. The present work investigated an alternative technique using a jelly as a contact medium over the entire fissure system so that the probe might record the overall caries status of the tooth reflecting the worst affected site. Readings were taken on 96 extracted teeth with dye‐coloured jelly acting as a contact medium. Readings were repeated on 32 teeth. Histological validation of caries status was carried out by visual examination of serial sections through each tooth to note the deepest lesion. The sensitivity and specificity of the overall electronic caries monitor readings were calculated for all lesions and dentine lesions only using selected resistance cut‐off points and presented as a series of Receiver Operating Characteristic (ROC) curves. The optimum sensitivity and specificity values were, for all lesions: 61% and 86%, and for dentine lesions: 76% and 76% respectively. The reproducibility of the readings was acceptable (Kappa values for all lesions= 0.76, for dentine lesions=0.55). The technique warrants further study as an overall reading may be more appropriate for epidemiological and clinical trial use.
The functional status of the masticatory system of 11–16‐year‐old adolescents: classification and validity
Authors: Sieber Martin , Ruggia Giovanni Maria , Grubenmann Eliusabeth , Palla Sabdro
Published: May 2006

Abstract Epidemiological studies to assess the prevalence and course of functional disturbances of the masticatory system should be based on a valid and reliable measure of the functional status of the masticatory system. Nielsenet al. (2, 3) proposed a classification method that included three different classes of dysfunction. This classification was used to compare the results of a sample of 447 11–16‐year‐old Swiss adolescents with those of the Danish study and to test the validity of this classification method. The two studies showed similar prevalences in two of the three dysfunction classes and a similar pattern of dysfunction categories. Concurrent and construct validity analyses showed significant correlations between the assessment from clinical examination and the subjective judgments of the adolescents. The results demonstrated cross‐ and concurrent validation of the “Nielsen index” but also stressed the necessity of a careful re‐evaluation of the “severe” class criterion. The limitations of the Nielsen index led to the construction of a “Zurich‐MAP index”. The potential applications of both indices are discussed.
Control of occlusal caries in the first permanent molars by oral hygiene
Authors: Arrow Peter
Published: May 2006

Abstract Caries of the pits and fissures of permanent teeth continues to be a problem for children, newly erupted permanent molars being particularly at risk. Oral hygiene measures have been shown to be able to reduce the incidence of caries. The aim of this study was to compare the caries‐preventive effects on newly erupted first permanent molars of a professional tooth cleaning and oral health education program (test) with a standard preventive program (control), comprising selective fissure sealing and application of topical fluorides. School Dental Service clinics of the Health Department of Western Australia, in Perth, were assigned to four test or four control clinics. Schoolchildren, mean age 6.3±0.3 (s) years with sound, newly erupted first permanent molars were included in the study (207 test, 197 control). After 12 months, 186 test and 163 control children were examined by an examiner who was ‘blind’ to the test or control status of the children. Caries of the first permanent molars developed in 34 test and 35 control children; the estimated risk ratio was 0.86 (95% CI 0.56, 1.30). Children in the test group had an average DFT score of 0.26±0.62 compared with 0.29±0.64 DFT in the control group (t‐test, P=0.67). The 12‐month results suggest that there was no statistically significant difference between the caries‐preventive effects of a professional tooth cleaning and oral health education program and a program based on selective fissure sealing and application of topical fluorides.
Oral disadvantage among dentate adults
Authors: Gilbert Gregg H. , Duncan R. Paul , Heft Marc W. , Dolan Teresa A. , Vogel W. Bruce
Published: May 2006

AbstractOral disadvantage can be defined as the avoidance of certain daily activities because of decrements in oral health. These decrements include oral disease and tissue damage, pain, and functional limitation. The Florida Dental Care Study (FDCS) is a longitudinal study of changes in oral health, which included at baseline 873 subjects who had at least I tooth, were 45 years old or older, and who participated for an interview and clinical examination. Three objectives of the FDCS are: (1) to describe selected psychometric properties of the measurement of oral disadvantage; (2) to describe oral disadvantage in a diverse sample of dentate adults; and (3) to describe the relationship between disadvantage and other aspects of oral health, such as disease/tissue damage, pain, and functional limitation. The prevalence of oral disadvantage within the previous 6 months, using eight self‐reported measures, ranged from 5% to 25%, depending upon the measure. Factor analysis suggested that oral disadvantage is best described as three factors: disadvantage due to (1) oral disease/tissue damage, (2) oral pain, and (3) oral functional limitation. Irregular dental attenders, poor persons, and blacks had the highest prevalence of oral disadvantage. Clinical measures of oral disease/tissue damage, self‐reported measures of oral disease/tissue damage, oral pain, and oral functional limitation were strongly associated with the presence of oral disadvantage. In multivariate analyses that accounted for differences in clinical measures of disease/tissue damage, self‐reported disease/tissue damage, oral pain, and oral functional limitation, females were more likely to report disadvantage due to disease/tissue damage, and middle‐aged persons and irregular dental attenders were more likely to report oral disadvantage due to pain. In these same regressions, differences in disadvantage due to race, poverty status, socioeconomic status, and rural/urban area of residence were not evident. These results have implications regarding the use of oral disadvantage to assess the long‐term effectiveness of dental care.
Nonresponse bias in a national study of dentists' infection control practices and attitudes related to HIV
Authors: McCarthy Gillian M. , MacDonald John K.
Published: May 2006

Abstract The aim was to investigate late response and nonresponse bias in a survey related to HIV and infection control. Questionnaires with ID numbers were mailed to a stratified random sample of dentists in Canada with additional mailings 4 and 7 weeks later (n=6444). We compared responses received after <4 weeks, 4–7 weeks, >7 weeks. Extrapolation was used to estimate nonresponse bias. Univariate analyses showed significant differences between responses received <4 weeks after initial mailing and those received later for items on sociodemographics, knowledge, infection control practices and attitudes: late responders were more likely to report that they would refuse to treat any patients with HIV (P<0.01). Multiple logistic regression indicated that the best predictors of responses received ≥4 weeks were disagreement that HBV is more infectious than HIV (OR=1.7); unwillingness to attend a dentist who treats HIV/AIDS patients (OR=1.3); incorrect perception of the risk of HIV infection after an HIV‐contaminated needlestick injury (OR =1.2): and sometimes or never heat‐sterilizing handpieces after each patient (OR=1.2). Extrapolation indicated that the percentage of all respondents who reported refusal to treat (15.2%) would have been 17.1% if a 100% response rate had been obtained. We found significant evidence of late response and nonresponse bias primarily in knowledge and fears related to HIV infectivity; however, the impact on the final results was small and we concluded that additional follow‐up to improve response rates would not be worthwhile.
Oral health condition of 12‐year‐old handicapped children in Flanders (Belgium)
Authors: Gizani Sotiria , Declerck Dominique , Vinckier Frans , Martens Luc , Marks Luc , Coffin Guy
Published: May 2006

Abstract The dental condition of 626 12‐year‐old handicapped children with mild mental or moderate to severe mental retardation or learning impairment, being 25% of the population of each of these groups, was examined in Flanders. An evaluation of oral cleanliness showed poor oral hygiene in 31.8% of the children. No significant differences were found in oral cleanliness among types of handicapping conditions. The mean DMFT score was 2.9 (s: 2.6) and DMFS score was 5.4 (s: 5.6). Almost 21% of the children were free of caries or fillings. No significant differences were found among groups of handicapped children. Handicapped children presented a low level of restorative care (restorative index score: 48.7%). Mildly mentally retarded children demonstrated the lowest restorative index (43.9%). The caries experience of first permanent molars represented the largest part of the DMFT score (64.1%). Sealants were present in 7.9% of children examined. A considerable percentage of mildly mentally retarded children and learning impaired children did not brush daily (22.1% and 20.9%) and did not receive help with toothbrushing from their parents or carers (91.0% and 94.7%, respectively).
Dental services utilization between 1977 and 1995 by Finnish adolescents of different socioeconomic levels
Authors: Honkala E. , Kuusela S. , Rimpelä A. , Rimpelä M. , Jokela J.
Published: May 2006

Abstract Equal distribution of health care services has long been a major goal of health policy in the Nordic countries. According to these guidelines, every child is expected to have an examination and treatment at least every second year. The aim of this study was to analyze the trends and, in particular, the socio‐economic differences in dental visits between 1977 and 1995. The data were collected as part of a nationwide research program, the Adolescent Health and Lifestyle Survey, which began in 1977. Every second year a self‐administered questionnaire was mailed to a representative sample of 14‐, 16‐ and 18‐year‐old Finns. The sample sizes in the surveys varied from 2422 to 9556, making a total of 56 605 subjects in the whole study. The response rates in different years varied from 77% to 88%. The percentage of adolescents visiting a dentist increased between 1977 and 1981 and thereafter remained stable. Dental visits seemed to correlate with the occupational and educational status of the parents up to 1983, but not after that. The Finnish primary oral health care policy seems to have gained a major objective by eliminating social inequality in dental service utilization among adolescents.
Two‐year incidence of tooth loss among South Australians aged 60+ years
Authors: Slade Gary D. , Gansky Stuart A. , Spencer A. John
Published: May 2006

Abstract Tooth loss diminishes oral function and quality of life, and national health targets aim to reduce population levels of tooth loss. Objectives: The purpose of this study was to determine tooth loss incidence and predictors of tooth loss among older adults in South Australia. Methods: Data were obtained from a cohort study of a stratified random sample of community‐dwelling dentate people aged 60+ years. Interviews and oral examinations were conducted among 911 individuals at baseline and among 693 of them (76.1%) 2 years later. Incidence rates and relative risks were calculated for population subgroups and multivariate logistic regression was used to construct risk prediction models. A method was developed to calculate 95% confidence intervals (95% CI) for relative risks (RR) from logistic regression models using a Taylor series approximation. Results: Some 19.5% (95% CI = 15.4‐23.6%) of people lost one or more teeth during the 2 years. Men, people with a recent extraction, people who brushed their teeth infrequently, smokers and people born outside Australia had significantly (P<0.05) greater risk of tooth loss. Baseline clinical predictors of tooth loss included more missing teeth, retained roots, decayed root surfaces, periodontal pockets and periodontal recession. In a multivariate model that controlled for baseline clinical predictors, former smokers (RR = 2.55, 95% C1=1.48‐4.40) and current smokers (RR = 2.06, 95% CI=0.92‐4.62) had similarly elevated risks of tooth loss compared with non‐smokers. Conclusions: The findings from this population suggest that a history of smoking contributes to tooth loss through mechanisms in addition to clinical disease processes alone.
S‐100 as a useful auxiliary diagnostic aid in tuberculoid leprosy
Authors: Gupta Sanjeev Kumar , Nigam Sonu , Mandal Ashish K. , Kumar Vijay
Published: May 2006

Background:  The diagnosis of tuberculoid leprosy is often difficult on hematoxylin and eosin (H&E) due to the absence of demonstrable nerve destruction. This study evaluates the utility of S‐100 staining in identifying nerve fragmentation and differentiation of tuberculoid leprosy from other cutaneous granulomatous diseases.

Methods:  Fifty cases of leprosy including 38 borderline tuberculoid (BT), two tuberculoid (TT), and 10 indeterminate leprosy (IL) were studied. Eleven controls of non‐lepromatous cutaneous granulomatous lesions were included. S‐100 was used for identifying the following dermal nerve patterns: infiltrated (A), fragmented (B), absent (C), and intact (D) nerves.

Results:  On H&E, only 18/38 (47.4%) BT cases and 1/2 (50%) TT cases revealed neural inflammation. On S‐100 staining of BT cases, 28/38 (73.7%) showed pattern B followed by patterns C and A in 8/38 (21.1%) and 2/38 (5.3%) cases, respectively. Both the TT cases showed pattern B. Only intact nerves (D) were seen in all the control cases. S‐100 identified nerve damage in 4/10 (40%) IL cases. The patterns A, B, and C had sensitivity, specificity, and positive and negative predictive values of 100% in diagnosing tuberculoid (BT + TT) leprosy.

Conclusions:  S‐100 is superior to H&E in identifying nerve fragmentation (p < 0.01). It also aids the differential diagnosis of tuberculoid leprosy.
Bcl‐2‐positive epidermal dendritic cells in inverted follicular keratoses but not squamous cell carcinomas or seborrheic keratoses
Authors: Ko Christine J. , Kim Jenny , Phan Jenny , Binder Scott W.
Published: May 2006

Aim:  In our previous research, bcl‐2‐positive dendritic cells were seen in increased numbers in suprabasal areas of inverted follicular keratoses (IFKs) compared to seborrheic keratoses (SKs). The purpose of this study was twofold; firstly, to support that these dendritic cells are Langerhans cells and secondly, to contrast the epidermal dendritic cells in IFKs, squamous cell carcinomas (SCCs), and SKs.

Methods:  Ten IFKs and five SKs previously showing bcl‐2‐positive dendritic cells within the epidermis were stained with CD1a. Fifteen other IFKs were stained with CD1a alone. Ten SCCs were stained with bcl‐2 and CD1a.

Results:  In the 10 IFKs stained with both bcl‐2 and CD1a, the density of CD1a‐positive cells correlated well with the density of bcl‐2‐positive dendritic cells; in the five SKs, the density of CD1a‐positive cells was similar to that seen in IFKs but was higher compared to the density of bcl‐2‐positive dendritic cells in SKs (p < 0.05). The IFKs had a significantly higher number of CD1a‐positive cells compared to SCCs (p < 0.01). SCCs showed bcl‐2‐positive cells only within the basal layer of the normal epidermis flanking the carcinomas.

Conclusion:  These results suggest that there is different bcl‐2 regulation of CD1a‐positive cells in IFKs, SKs, and SCCs.
Morphology of Malassez's epithelial rest‐like cells in the cementum: transmission electron microscopy, immunohistochemical, and TdT‐mediated dUTP‐biotin nick end labeling studies
Authors: Suzuki M. , Matsuzaka K. , Yamada S. , Shimono M. , Abiko Y. , Inoue T.
Published: May 2006

Background and Objective:  It is known that epithelial islands are embedded in the cementum during tooth root formation, but details of this process remain unknown. The purpose of this study was to investigate the dynamic characteristics of Malassez's epithelial rest cells in the cementum during tooth root formation in pigs in vivo.

Material and Methods:  The first molars of 6‐mo‐old pigs were used in this study. Specimens were decalcified before being embedded in paraffin. Paraffin sections were investigated using TdT‐mediated dUTP‐biotin nick end labeling (TUNEL), immunohistochemical, and ultrastructural techniques.

Results:  Malassez's epithelial rest cells were located close to the root surface at the apical one‐third of the periodontal ligament, and epithelial clusters surrounded by distinct lamina cementia were sometimes observed in the cementum. TUNEL‐positive cells were detected only in the cementum. Malassez's epithelial rest cells in the periodontal ligament were completely surrounded by basement membranes, but epithelial clusters in the cementum were only intermittently surrounded by such membranes. Cytokeratin‐positive cells in the superstratum of the cementum were directly connected by cementocytes and by desmosome‐like structures. However, organelles were scarce in the cytokeratin‐positive cells in the substratum of the cementum, and the matrix of the cementum was deposited in the cells.

Conclusion:  These results suggest that the majority of the fragmented Hertwig's root sheath remains in the periodontal ligament and that some cells, which are connected to cementoblasts, are embedded in the cementum and progress to apoptosis.
Climate change, migratory connctivity and changes in laying date and clutch size of the pied flycatcher
Authors: Laaksonen Toni , Ahola Markus , Eeva Tapio , A. Väisänen Risto , Lehikoinen Esa
Published: May 2006

We examined long‐term (1943–2003) variability in laying dates and clutch sizes in a Finnish population of the pied flycatcher Ficedula hypoleuca Pallas, and analysed whether potential changes were explained by changes in climatic factors at the wintering area in Africa, at migration route or at breeding grounds. Among‐year variation in both mean and skewness of laying dates increased, which for mean laying date appeared to be explained by variability of temperatures at the breeding grounds and for skewness by variable temperature trends along the migration route. Pied flycatchers bred earlier in warm springs, but despite a warming trend in pre‐laying temperatures, the laying dates tended to delay. Laying dates became continuously later in relation to the phenology of the environment. Mean clutch size decreased with time when mean laying date was controlled for, but the climatic factors did not appear to explain the decrease. The advancement of spring phenology may have shifted some food sources needed for egg‐laying, thus leading to later laying and smaller clutches. Variation in clutch size increased when wintering conditions were favourable so that clutch size distribution was skewed with a tail of small clutches when there had been lot of rainfall (more vegetation and insects) in the wintering area. We suggest that when ecological conditions during winter were good, the tail of small clutches represented low‐quality individuals that were not able to breed after bad winters. Our analyses demonstrate that measures of spread and symmetry give different information about population level changes than means, and thus complement the understanding of the potential influences of climate change on populations.
Tri‐trophic effects of plant defenses: chickadees consume caterpillars based on host leaf chemistry
Authors: S. Müller Martina , R. McWilliams Scott , Podlesak David , R. Donaldson Jack , M. Bothwell Helen , L. Lindroth Richard
Published: May 2006

Few studies have addressed how plant chemical defenses that directly affect herbivores in turn affect consumption patterns of vertebrates at higher trophic levels. We studied how variable foliar chemistry of trembling aspen (Populus tremuloides Michx.) affects the diet preferences of an avian insectivore feeding on an introduced herbivore, the gypsy moth (Lymantria dispar L.).

Black‐capped chickadees (Poecile atricapilla) were offered paired choices of gypsy moth caterpillars feeding on one of three genotypes of aspen that differed in chemical composition. Chickadees chose to eat caterpillars fed aspen foliage with low levels of both condensed tannins and phenolic glycosides, or caterpillars fed foliage with high levels of tannins and low levels of phenolic glycosides, over caterpillars fed foliage with low levels of condensed tannins and high levels of phenolic glycosides. In addition, diet choices of the birds were affected by their previous experience. These findings are consistent with the “extended phenotype” concept, in that genetically‐based chemical traits in an ecologically dominant plant influence the feeding behavior of third trophic level organisms, whose efficacy as regulators of herbivore populations may in turn be modified.
Relationship between tree size and insect assemblages associated with Anadenanthera macrocarpa
Authors: Campos Ricardo I. , Vasconcelos Heraldo L. , Ribeiro Sérvio P. , Neves Frederico S. , Soares Janaina P.
Published: May 2006

This study analyzed the effects of tree size, and correlated architectural tree characteristics, on the assemblages of ants and insect herbivores associated with Anadenanthera macrocarpa (Mimosaceae). The latter is a myrmecophilous tree species from the Atlantic rainforest in south‐eastern Brazil. Ants and insect herbivores were collected in 30 individuals of A. macrocarpa, ranging from young individuals (>3 m in height) to emergent trees (up to 40 m). Tree height was a strong indicator of other tree characteristics, including trunk diameter, crown height, crown volume, and number of bifurcations. Ants were collected using arboreal pitfall traps and beating, while insect herbivores with beating only. There was a significant increase in both abundance and species richness of ants and insect herbivores with an increase in tree height. In addition, tree height had a significant effect on the species composition of ants and insect herbivores. Assemblages of both taxa showed a nested organization pattern. The species found in small‐ and medium‐sized trees, in general, consisted of a subset of the species found in the crowns and branches of larger, canopy or emergent trees. Thus, in A. macrocarpa, there was not a replacement of insect species with plant ontogeny. This finding is at variance with those conducted in tropical evergreen forests and which show a clear stratification between the understory and canopy insect faunas. Additional studies are needed to explain these contrasting patterns, but it is possible that differences in microclimate are involved. As the forest we studied is semi‐deciduous, microclimatic gradients between the understory and the canopy habitat are probably less severe than in an evergreen forest, thus resulting in a lower turnover of species.
Altitude and woody cover control recruitment ofHelleborus foetidusin a Mediterranean mountain area
Authors: Ramírez José M. , Rey Pedro J. , Alcántara Julio M. , Sánchez‐Lafuente Alfonso M.
Published: May 2006

This study explores how variation of macro‐ and micro‐climatic conditions associated with changes in altitude affect early recruitment dynamics of the perennial herbHelleborus foetidus(Ranunculaceae). We also analyse the relevance of facilitation by woody vegetation on seedling recruitment along altitudinal gradient. We conducted a sowing experiment testing the effect of altitude (using three populations located at 1100, 1400 and 1650 m a.s.l.) and woody cover (open areas vs cover of woody species) on seedling emergence during two years and survival three years after sowing. Simultaneously, we characterised elevations and cover types in terms of climatic factors (surface air temperature and relative humidity) throughout a whole year, and light conditions (global site factor and red/infrared ligh ratio) using hemispheric photographs. We detected a significant effect of elevation on seedling emergence, with a higher emergence at lowest altitude. Woody cover greatly affected seedling survival and recruitment, both rates being higher under woody species than in open areas. Emergence was negatively correlated with winter stress factors, which increased with elevation. Survival and recruitment were negatively correlated with summer stress factors, which were ameliorated by woody cover and with altitude. Amelioration of climatic factors by woody cover was not influenced by altitude. Implications for species persistence in Mediterranean mountains under climate change scenarios are discussed.
DEFINITION AND ANALYSIS OF A WAVELET/FICTITIOUS DOMAIN SOLVER FOR THE 2D-HEAT EQUATION ON A GENERAL DOMAIN
Authors: BACCOU JEAN , LIANDRAT JACQUES
Published: May 2006

This paper is devoted to the setting and analysis of a Petrov–Galerkin wavelet-fictitious domain numerical method for the approximation of the solution of multi-dimensional parabolic equations on a general domain.

In this method, the original parabolic equation, set on a domain ω, is first discretized in time using a finite difference scheme. At each time step, the corresponding elliptic equation on ω is transformed into a saddle point problem on a functional space defined on a bigger but simply shaped domain Ω where the initial boundary conditions on ω are enforced using surface Lagrange multipliers (Ref. 2). The solution of this problem is then approximated, thanks to a Petrov–Galerkin formulation, using wavelets and time scheme associated "vaguelettes" (Ref. 8).

Existence, uniqueness and convergence of the approximated solution, when finite dimension spaces are used, are established and the efficiency as well as the stability of the numerical algorithm (namely the Uzawa algorithm) used in the resolution are analyzed. The constraint of a discrete inf-sup condition as well as ill-conditioning associated to the trace operator are investigated in the wavelet framework.

Numerical results related to the 2D heat equation are presented.
A TRUNCATION METHOD FOR DETECTING SINGULAR MINIMIZERS INVOLVING THE LAVRENTIEV PHENOMENON
Authors: BAI YU , LI ZHI-PING
Published: May 2006

A numerical method using the truncation technique on the integrand is developed for computing singular minimizers or singular minimizing sequences in variational problems involving the Lavrentiev phenomenon. It is proved that the method can detect absolute minimizers with various singularities whether the Lavrentiev phenomenon is involved or not. It is also proved that, when the absolute infimum is not attainable, the method can produce minimizing sequences. Numerical results on Manià's example and a two-dimensional problem involving the Lavrentiev phenomenon with continuous Sobolev exponent dependence, are given to show the efficiency of the method.
ON SECOND NOETHER'S THEOREM AND GAUGE SYMMETRIES IN MECHANICS
Authors: CARIÑENA JOSÉ F. , LÁZARO-CAMÍ JOAN-ANDREU , MARTÍNEZ EDUARDO
Published: May 2006

We review the geometric formulation of the second Noether's theorem in time-dependent mechanics. The commutation relations between the dynamics on the final constraint manifold and the infinitesimal generator of a symmetry are studied. We show an algorithm for determining a gauge symmetry which is closely related to the process of stabilization of constraints, both in Lagrangian and Hamiltonian formalisms. The connections between both formalisms are established by means of the time-evolution operator.
HIGHER-ORDER DISCRETE LAGRANGIAN MECHANICS
Authors: BENITO ROBERTO , DE LEÓN MANUEL , DE DIEGO D. MARTÍN
Published: May 2006

In this paper we develop the construction of geometric integrators for higher-order mechanics. These integrators are naturally symplectic and preserve momentum since they have a discrete variational origin.
THE STRUCTURE OF SPACE–TIME: RELATIVITY GROUPS
Authors: MARMO GIUSEPPE , PREZIOSI BRUNO
Published: May 2006

The structure of space–time is analyzed by introducing a coordinate-free formulation of reference frame. Relativity groups emerge through the notion of equivalent frames. By means of the notion of objective existence, we show that transformations connecting equivalent frames are either Lorentz or generalized Galilei.
GEOMETRIC EXPLANATION OF THE BELTRAMI THEOREM
Authors: MATVEEV VLADIMIR S.
Published: May 2006

We present a new proof of the classical Beltrami Theorem stating that a metric projectively equivalent to a metric of constant curvature is itself a metric of constant curvature.
THE COVARIANT PICARD GROUPOID IN DIFFERENTIAL GEOMETRY
Authors: WALDMANN STEFAN
Published: May 2006

In this paper we discuss some general results on the covariant Picard groupoid in the context of differential geometry and interpret the problem of lifting Lie algebra actions to line bundles in the Picard groupoid approach.
Systemic Pressures and the Intersubjective Bases of State Autonomy in Russia: A Constructivist-Institutionalist Theory of Economic Crisis and Change
Authors: Baglione Lisa A. , Widmaier Wesley W.
Published: May 2006

Over the economic crises of the 1990s, global economic understandings shifted from the early classical orthodoxy of the ‘Washington Consensus’ to a later Keynesian support for demand stimulus and capital controls. However, Russian policy – particularly after the 1998 ruble crisis – partly deviated from these broader trends, combining Keynesian capital controls with classical budgetary restraint. In offering a ‘constructivist-institutionalist’ explanation for this policy mix, we assume that agents can always interpret or construct events as varying types of crises, reshaping state society relations in the process. We then argue that classical interpretations of the early 1990s' crises legitimated orthodox policies and more importantly – alienated the Russian state from society. Given this backdrop, while later interpretations of the 1998 ruble crisis legitimated capital controls, the prior alienation of state from society precluded any domestic Keynesian coalition. Global pressures must, from this vantage point, be situated in specific social and institutional contexts.
Digitized content in the UK research library and archives sector
Authors: Bültmann Barbara , Hardy Rachel , Muir Adrienne , Wictor Clara
Published: May 2006

A study of the current provision of digitized collections for researchers in the UK higher education sector was carried out through desk research, a Web-based questionnaire of research libraries and interviews. The study identified a great deal of digitized material in the sector and there has been considerable expenditure of UK public funds in the creation of digital material in the last ten years. However, funding of digitization has been piecemeal and uncoordinated. It is clear that there is a need for coordination, but no agreement on how it should be implemented. Any future national approach would have to be a coordinated and distributed, rather than centralized, one.
Sovereign Inequalities and Hierarchy in Anarchy: American Power and International Society
Authors: Donnelly Jack
Published: May 2006

How is unrivalled American power reshaping 21st-century international society? Is the United States an empire, in fact or in the making? This article attempts to elaborate the conceptual resources required to answer such questions. I focus on multiple forms of hierarchy in anarchy and diverse practices of sovereign inequality—concepts that most mainstream perspectives ignore, find paradoxical, or even dismiss as self-contradictory. After defining empire and hierarchy in anarchy, I present a typology of international orders tuned to thinking about empire and its alternatives. The central section of the article explores three classes of formal inequalities common during the Westphalian era—special rights of Great Powers, restricted rights for outlaws, and a wide range of particular practices of ‘semi-sovereignty’. I then sketch ten historically grounded models of hierarchical international relations. Two brief applications to contemporary American power seek to illustrate the value of this conceptual apparatus. Throughout, my focus is on appreciating the precise nature and considerable variety of international inequalities. I argue that the concepts of hierarchy in anarchy and sovereign inequality, but not empire, are essential for understanding the shape and development of contemporary international order.
Coming in from the Cold: Constructivism and Emotions
Authors: Ross Andrew A. G.
Published: May 2006

A variety of constructivists have begun to address emotions in IR, viewing emotional events and memories as important dimensions to the social construction of identity. But it is not clear that constructivist tools, designed in most cases for interpreting discursive representations, are equipped to study affective phenomena. This article offers a critical assessment of constructivism’s ability to theorize affects—nonconscious and embodied emotional states—in global politics. Using as an example the ontology developed by Alexander Wendt, the article suggests that common presuppositions in orthodox constructivism in fact obstruct the study of affect and its role in social and political life. To grasp the depth, intensity, and fugitivity of emotional phenomena, constructivism needs to rethink its attachments to reflective agency, ideational processes, and symbolic meaning. Through a brief discussion of the American response to 9/11, the final section develops several propositions on the role of affect in forging political identities.
Domestic Instability and Security Communities
Authors: Nathan Laurie
Published: May 2006

The problem of political instability is neglected in the literature on security communities. In this article I argue that domestic stability, defined as the absence of large-scale violence in a country, is a necessary condition of these communities. Domestic violence precludes the existence of security communities because it renders people and states insecure; it creates the risk of cross-border destabilization and violence; and it generates uncertainty and tension among states, inhibiting trust and a sense of collective identity. I conclude that the benchmark of a security community—dependable expectations of peaceful change—should apply as much within states as between them. This is consistent with the work of Karl Deutsch, whose pioneering concept of a security community is widely understood to mean the absence of interstate war. Deutsch, in fact, was equally concerned with large-scale internal violence.