A Decentralized Fuzzy Rule-Based Approach for Computing Topological Relations between Spatial Dynamic Continuous Phenomena with Vague Boundaries Using Sensor Data.

Sensor networks (SN) are increasingly used for the observation and monitoring of spatiotemporal phenomena and their dynamics such as pollution, noise and forest fires. In multisensory systems, a sensor node may be equipped with different sensing units to observe and detect several spatiotemporal phenomena at the same time. Simultaneous detection of different phenomena can be used to infer their spatial interactions over space and time. For this purpose, decentralized spatial computing approaches have shown their potential for effective reasoning on spatial phenomena within a sensor network. However, in most cases, spatial extents of continuous dynamic phenomena are uncertain, and their relations and interactions cannot be inferred by the existing approaches at the sensor node level. To address this limitation, in this paper, we propose and develop a decentralized fuzzy rule-based spatial reasoning approach to depict the spatial relations that hold between two evolving spatial phenomena with fuzzy boundaries. The proposed method benefits from a more adapted fuzzy-crisp representation of dynamic phenomena observed by SN where each vague phenomenon is composed of five distinguished zones including the kernel, conjecture and exterior zone and their boundaries. For each detected phenomenon, a sensor node will report one of these zones based on its location. Aggregation of the information reported from the sensor nodes allows reasoning on spatial relations between the observed phenomena and their evolution. Such spatial information provides users with more valuable near real-time information on the state of different phenomena that can be used for informed decision-making.

Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay.

The combined effects of anthropogenic and biological CO2 inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H2S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. We show that a pH minimum occurs in mid-depths where acids are generated as a result of H2S oxidation in waters mixed upward from the anoxic depths. Our analyses also suggest a large synergistic effect from river-ocean mixing, global and local atmospheric CO2 uptake, and CO2 and acid production from respiration and other redox reactions. Together they lead to a poor acid buffering capacity, severe acidification and increased carbonate mineral dissolution in the USA's largest estuary.The potential contribution of redox reactions to acidification in coastal waters is unclear. Here, using measurements from the Chesapeake Bay, the authors show that pH minimum occurs at mid-depths where acids are produced via hydrogen sulfide oxidation in waters mixed upward from anoxic depths.

A mixed method study of propensity for participatory evaluation.

One way to increase the use of evaluation results is practical participatory evaluation (PPE), which enables non-evaluator participants to join the evaluation process in a participatory mode. We examined the propensity for PPE of health professionals by focusing on four components: learning, working in groups, using judgment and using systematic methods. We interviewed the professionals at a Haitian health institution to determine their positioning on a scale of propensity (low, medium and high) for the four components. The professionals defined each component in relation to the energy puts into them, being more or less proactive. Facilitating elements for all three levels of propensity integration included past positive experiences, external pressure and a desire for better individual and organizational performance. Impeding factors included a lack of available resources perceived responsibilities and commitments toward private patients. The reported advantages included improved organizational performance and idea sharing, and the disadvantages included availability of, difficulty implementing solutions and altered human relationships.

Associations between school deprivation indices and oral health status.

BACKGROUND: Despite an overall improvement in oral health status in several countries over the past decades, chronic oral diseases (COD) remain a public health problem, occurring mostly among children in the lower social strata. The use of publicly available indicators at the school level may be an optimal strategy to identify children at high risk of COD in order to organize oral health promotion and intervention in schools. OBJECTIVE: To investigate whether school deprivation indices were associated with schoolchildren oral health status. METHODS: This ecological study used a sample of 316 elementary public schools in the province of Quebec, Canada. Data from two sources were linked using school identifiers: (i) Two school deprivation indices (in deciles) from the Ministry of Education, a poverty index based on the low income cut-offs established by Statistics Canada and a socioeconomic environment index defined by the proportions of maternal under-schooling and of unemployed parents and (ii) Oral health outcomes from the Quebec Schoolchildren Oral Health Survey 1998-99 aggregated at the school level. These included proportions of children with dental caries and reporting oral pain. The relation between school deprivation indices and oral health outcomes was assessed with linear regression for dental caries experience and logistic regression for oral pain. RESULTS: The mean DMF-S (mean number of decayed, missing and filled permanent teeth surfaces) by school was 0.7 (SD = 0.5); the average proportions of children with dental caries and reporting oral pain were 25.0% and 3.0%, respectively. The poverty index was not associated with oral health outcomes. For the socioeconomic environment index, dental caries experience was 6.9% higher when comparing schools in unfavourable socioeconomic environments to the most favourable ones [95% confidence interval (CI): 2.1, 11.7%]. Furthermore, the most deprived schools, as compared to least deprived ones, were almost three times as likely to have children reporting oral pain in the previous week. CONCLUSION: The school socioeconomic environment index was associated with oral health outcomes, and should be studied for its potential usefulness in planning school-based oral health promotion and screening strategies.

Ethics and the compensation of immigrant workers for work-related injuries and illnesses.

This paper examines the compensation process for work-related injuries and illnesses by assessing the trajectories of a sample of immigrant and non-immigrant workers (n = 104) in Montreal. Workers were interviewed to analyze the complexity associated with the compensation process. Experts specialized in compensation issues assessed the difficulty of the interviewees' compensation process. Immigrant workers faced greater difficulties with medical, legal, and administrative issues than non-immigrants did. While immigrant workers' claim forms tended to be written more often by employers or friends (58% vs. 8%), the claims were still more often contested by employers (64% vs. 24%). Immigrant workers were less likely to obtain a precise diagnosis (64% vs. 42%) and upon returning to work were more likely to face sub-optimal conditions. Such results throw into relief issues of ethics and equity in host societies that are building their economy with migrant workers.

Expression of fully assembled TCR-CD3 complex on double positive thymocytes: synergistic role for the PRS and ER retention motifs in the intra-cytoplasmic tail of CD3epsilon.

TCR expression on double-positive (DP) thymocytes is a prerequisite for thymic selection that results in the generation of mature CD4(+) and CD8(+) single-positive T cells. TCR is expressed at very low level on preselection DP thymocytes and is dramatically up-regulated on positively selected thymocytes. However, mechanism governing TCR expression on developing thymocytes is not understood. In the present report, we demonstrate that the intra-cytoplasmic (IC) domain of CD3epsilon plays a critical role in regulating TCR expression on DP thymocytes. We provide genetic and biochemical evidence to show that the CD3epsilon IC domain mutations result in elevated expression of fully assembled TCR on DP thymocytes. We also demonstrate that TCR up-regulation on DP thymocytes in these transgenic mice occurs in a ligand-independent manner. Further, we show that the proline-rich sequence and endoplasmic reticulum (ER) retention motifs in the IC domain of CD3epsilon play synergistic role in regulating TCR surface expression on DP thymocytes.

Disentangling the relative influence of built and socioeconomic environments on walking: the contribution of areas homogenous along exposures of interest.

The geography of small areas has important implications for studying the contextual determinants of health because of potential errors when measuring ecologic exposures and estimating their effects on health. In this paper, we present an approach for designing homogeneous zones optimising the spatial distribution of an area-level exposure, active living potential (ALP), based on data collected in Montreal, Canada. The objectives are to (1) assess and compare variation in walking behaviours between these purposefully designed zones and between standard administrative units, census tracts; and (2) disentangle the relative influence of ALP and area-level socioeconomic conditions on walking using the alternative geographies. Zones were designed by statistically classifying smallest census areas (disseminations areas) into seven categories of exposure similar along three indicators of ALP: population density, land use mix, and geographic accessibility to services. Mapping of categories resulted in the delineation of zones characterised by one of seven levels of ALP. A sample of 2716 adults aged >/=45 years was geocoded and cross-classified in 270 zones and 112 census tracts. Individuals reported on minutes and motives of walking and provided socioeconomic information. Data were analysed using cross-classified multilevel models. Variation in utilitarian walking was larger across the purposefully defined zones than across census tracts. Total walking varied significantly between census tracts only. Greater ALP was associated with more utilitarian walking but with less recreational walking. Higher socioeconomic position in census tracts was positively associated with total, utilitarian, and recreational walking. The soundness of standard administrative units for measuring ecologic exposure and their associations with health should be considered prior to conducting analyses. The added value of different approaches for understanding how place relates to health remains to be established and should be the focus of further investigations.

Critical and multiple roles for the CD3epsilon intracytoplasmic tail in double negative to double positive thymocyte differentiation.

The preTCR is associated with signal-transducing CD3gamma, delta, epsilon, and zeta polypeptides. It is generally agreed that CD3 chains play redundant roles in the receptor-mediated signal transduction. In the present study, we show that the intracytoplasmic (IC) domain of CD3epsilon is essential for early thymocyte maturation. We demonstrate that the IC domain-deleted CD3epsilon fails to restore the double negative (DN) to double positive (DP) thymocyte development in CD3epsilon-deficient mice. Additional experiments show that the membrane proximal basic amino acid rich sequence in the IC domain of CD3epsilon is sufficient for the DN to DP differentiation, whereas the proline rich sequence is required for efficient proliferation. This is probably due to impaired ligand independent recruitment of Nck to the proline rich sequence motif of CD3epsilon within the context of the preTCR. The data presented in this study elucidates mechanistic basis for the preTCR-induced proliferation of the DN thymocytes and have identified distinct roles for individual motifs of CD3epsilon in the preTCR-mediated differentiation and proliferation. These data provide the first genetic and phenotypic evidence for requirement of the IC domain of a CD3 chain in thymocyte development.

Eating-disorder symptoms and syndromes in a sample of urban-dwelling Canadian women: contributions toward a population health perspective.

OBJECTIVE: We estimated the prevalence of eating disorders and maladaptive eating behaviors in a population-based sample and examined the association of maladaptive eating with self-rated physical and mental health. METHOD: A sample of 1,501 women (mean age = 31.2 years, SD = 6.2) were recruited using random-digit dialing to participate in a 20-min telephone interview about eating behaviors. RESULTS: Weighted frequency analysis showed the prevalence of frequent binge-eating to be 4.1%, that of regular purging to be 1.1%, and that of frequent compensation to be 8.7%. Although we found none of the women to meet full criteria for anorexia nervosa, 0.6% met criteria for bulimia nervosa, 3.8% provisional criteria for binge eating disorder, and 0.6% criteria for a newly proposed entity, purging disorder. As many as 14.9% fell into a residual category representing subthreshold, but potentially problematic variants of eating disturbances. Logistic regression analyses showed that clinical-level maladaptive eating attitudes and behaviors predicted self-rated physical- and mental-health problems after sociodemographic factors were controlled. DISCUSSION: This population-based survey provides prevalence estimates of BN, BED, and purging disorder that are compatible with those of recent epidemiological studies and shows that maladaptive eating attitudes and behaviors represent a substantial population burden.

Dental caries, problems perceived and use of services among institutionalized elderly in 3 regions of Quebec, Canada.

OBJECTIVES: To determine the changes, since 1980, in the number of nontreated caries in elderly people who have retained their teeth and are in residential and long-term care centres (CHSLDs) in the province of Quebec, Canada, and the changes in their perception of their oral health problems and use of dental services. METHODS: A secondary analysis of data from a 2004-2005 survey about the oral health problems of people who were at least 65 years of age and living in CHSLD institutions in the Montreal, Montérégie and Quebec City regions was done. The inclusion criterion for the secondary analysis was that the residents had to have at least 1 natural tooth. Data from the 152 residents who met the inclusion criterion were analyzed, and compared with those from a similar study done in 1980. RESULTS: Since 1980, the average number of teeth retained rose from 11.05 (SD 6.78) teeth to 12.91 (SD 7.82) in 2004. The average number of decayed teeth requiring treatment fell from 2.43 (SD 2.88) to 1.62 (SD 2.53); 49.3% (75/152) of the elderly participants had caries, compared with 74.1% in 1980. Only 3.4% (5/149) of the participants reported problems with, or pain or discomfort in their gums, compared with 8.9% in 1980. About half (48.7% or 74/152) of the participants examined needed periodontal treatment; 63.8% (83/130) had had recourse to services within the previous 5 years. The last time care was sought was, on average ,7.1 years ago, compared with 11.0 years in 1980. CONCLUSIONS: Between 1980 and 2004, the number of retained teeth increased and the number of untreated caries fell among institutionalized elderly people. Their perception of the need for dental care remained poor. Their use of services improved, but was not ideal, given the numerous oral health problems diagnosed in this population.

Establishing the soundness of administrative spatial units for operationalising the active living potential of residential environments: an exemplar for designing optimal zones.

BACKGROUND: In health and place research, definitions of areas, area characteristics, and health outcomes should ideally be coherent with one another. Yet current approaches for delimiting areas mostly rely on spatial units "of convenience" such as census tracts. These areas may be homogeneous along socioeconomic conditions but heterogeneous along other environmental characteristics. This heterogeneity can lead to biased measurement of environment characteristics and misestimation of area effects on health. The objective of this study was to assess the soundness of census tracts as units of analysis for measuring the active living potential of environments, hypothesised to be associated with walking. RESULTS: Starting with data at the smallest census area level available, zones homogeneous along three indicators of active living potential, i.e. population density, land use mix, and accessibility to services were designed. Delimitation of zones ensued from statistical clustering of the smallest areas into seven clusters or "types of environment". Mapping of clusters into a GIS led to the delineation of 898 zones characterised by one of seven types of environment, corresponding to different levels of active living potential. Homogeneity of census tracts along indicators of active living potential varied. A greater proportion (83%) of variation in accessibility to services was attributable to differences between census tracts suggesting within-tract homogeneity along this variable. However, census tracts were heterogeneous with respect to population density and land use mix where a greater proportion of the variation was attributable to within-tract differences. About 55% of tracts were characterised by a combination of three or more "types of environment" suggesting substantial within-tract heterogeneity in the active living potential of environments. CONCLUSION: Soundness of census tracts for measuring active living potential may be limited. Measuring active living potential with error may lead to misestimation of associations with walking, therefore limiting the correctness of inference about area effects on walking. Future studies should aim to determine homogeneity of spatial units "of convenience" along environment characteristics of interest prior to examining their association with health. Further evidence is needed to assess the extent of this methodological issue with other indicators of environment context relevant to other health indicators.

Promoting active living among people with physical disabilities evidence for neighborhood-level buoys.

BACKGROUND: People with physical disabilities are more likely to be sedentary than the general population, possibly because they have an accrued sensitivity to environmental features. OBJECTIVES: This paper describes the relationship between neighborhood-level active living buoys and the active living practices of adults with physical disabilities living in a large urban area. METHODS: A sample of 205 people with physical disabilities was recruited via a local rehabilitation center and its adapted fitness center. Telephone interviews were administered by senior occupational therapy students. The interview included a modified version of the Physical Activity and Disability Survey, a validated instrument that includes questions on physical activity, active transportation, and other activities of daily living. Individuals were geocoded within their census tract of residence (n=114) using their postal codes. Data on neighborhood active living potential were gleaned from systematic social observation. RESULTS: Multilevel logistic regression analyses showed that the association between the presence of environmental buoys and leisure activity was significant (OR=4.0, 95% CI=1.1-13.8) despite adjustments for individual difference variables while the association with active transportation became nonsignificant (OR=2.9, 95% CI=0.7-7.7) following adjustment for these variables. CONCLUSIONS: People with physical disabilities who live in neighborhoods with more environmental buoys are more likely to report involvement in leisure-time physical activity.

Buprenorphine substitution treatment in France: drug users' views of the doctor-user relationship.

The French system for drug substitution, or maintenance treatment, established in 1996, differs from the often strict conditions attached to methadone clinics in other countries. Because of the predominant role of general practitioners and the flexible prescription rules for Subutex in France, the relationship between the physician and the drug user becomes a central element in the treatment. This article deals with the expectations that these users have of the physician, and their perception of his or her attitude towards them. In order to identify possible reasons for the absence of treatment compliance and of Subutex misuse, it focuses on the users' assessment of the physician's response to the problems they report. This study, based on a diversified convenience sample of 28 persons (19 men, 9 women) in treatment, showed 4 patterns of relationships between physicians and users, which differed in their focus: (1) closely focused on the posology of the prescription; (2) compliance with the prescribed regimen is the main issue in a relationship dominated by the physician; (3) an alliance between the physician and the user who is acknowledged as a person, and (4) a instrumental solely on the part of the user, who comes to procure a free, legal drug from a doctor's office. In all four case types, users had difficulty reporting other drug use or intravenous Subutex injection within this relationship, in which the stigma attached to drug dependence seems to reappear. Moreover, the lack of clarity about the treatment objectives and the time frame of the consultation limits the users' ability to integrate the treatment into their lives and to commit themselves to it. The heterogeneity and fragility of the users' situations, and the treatment objectives require regular assessment during contact with the physician. This constant reappraisal of the situation with the physician should help to optimize the treatment and avoid the hiatus that can generate or continue "misuse."

Neighborhood-level active living buoys for individuals with physical disabilities.

BACKGROUND: In an effort to advance the research agenda on residential determinants of active living among people with physical disabilities, the purposes of this paper are (1) to describe the extent to which environmental supports (buoys) promoting active living among individuals with disabilities are present in neighborhoods located in a large urban area, and (2) to examine the association between the presence of these buoys and neighborhood-level indicators of affluence, proportions of individuals with disabilities living in the neighborhood, and other neighborhood active living indicators. METHODS: In the context of a larger project, pairs of evaluators assessed potential determinants of active living in 112 neighborhoods (census tracts) on the island of Montreal, Canada, in the summer of 2003. The assessment grid included 18 items related to active living for the general population and three specifically for people with physical disabilities. RESULTS: Analyses performed in 2006 show that few neighborhoods in this large urban area are equipped with environmental buoys that might support active living among people with physical disabilities. Lower levels of environmental buoys to promote active living among those with disabilities were most strongly associated with lower levels of neighborhood activity-friendliness. Less consistent associations were observed between lower environmental buoys and lower density of destinations, greater safety, lower proportions of people with disabilities, and higher proportions of those of low income. CONCLUSIONS: More research is needed to better understand the distribution of environmental buoys in residential areas and their influences on active living among people with physical disabilities.

Different role for mouse and human CD3delta/epsilon heterodimer in preT cell receptor (preTCR) function: human CD3delta/epsilon heterodimer restores the defective preTCR function in CD3gamma- and CD3gammadelta-deficient mice.

The majority of T cell receptor (TCR) complexes in mice and humans consist of a heterodimer of polymorphic TCRalpha and beta chains along with invariant CD3gamma, delta, epsilon, and zeta chains. CD3 chains are present as CD3gammaepsilon, deltaepsilon, and zetazeta dimers in the receptor complex and play critical roles in the antigen receptor assembly, transport to the cell surface, and the receptor-mediated signal transduction. That CD3 chains play critical roles in thymocyte development is apparent from the analyses of CD3 deficient mice. PreT cell receptor (preTCR)-mediated CD4(-)CD8(-) (double negative or DN) to CD4(+)CD8(+) (double positive or DP) transition is severely impaired in mice deficient in either CD3gamma, or epsilon, or zeta chain. In contrast, CD3delta deficiency impairs thymocyte maturation at the CD4(+)CD8(+) double positive (DP) stage suggesting that CD3delta is not required for the preTCR-mediated DN to DP transition. However, recent data suggest that a defect in human CD3delta results in impaired development at the DN stage indicating a role for hCD3delta in preTCR-mediated DN to DP transition. To determine if human CD3delta/epsilon (hCD3delta/epsilon) could mediate preTCR-mediated DN to DP transition, we employed a human CD3 transgene that encodes full length CD3delta and a truncated but functional form of CD3epsilon. Surprisingly, the transgene restored the defective preTCR function in not only CD3epsilon- but CD3gamma- and CD3gammadelta-deficient mice as well. A possible role for human CD3delta/epsilon heterodimer in the preTCR-mediated DN to DP transition is discussed.

The diversity of prevention and health promotion services offered by Québec Community Health Centres: a study of infant and toddler programmes.

Research has shown that preventive and health promotion (PHP) services offered by community health centres are often vulnerable in times of health reform or budgetary cutbacks. The present study was conducted in Québec, Canada, approximately 10 years after the start of a major transformation of health care services. The objectives were: (1) to examine the diversity of infant/toddler prevention and health promotion services offered by centres locaux de services communautaires (CLSCs, local community health and social services centres); and (2) to investigate the organisational and environmental correlates of such diversity. All Québec CLSCs were invited to complete a survey questionnaire regarding their PHP services (response rate = 69%). Data on environmental and organisational factors were extracted from existing Québec government data sets. Bivariate and multivariate analyses were performed to identify the correlates of the CLSCs' level of diversity of PHP services. The results revealed that CLSCs varied greatly in terms of their diversity of PHP services. The number of full-time equivalents in the Child and Family Services Programme (one of two programmes aimed at reaching the targeted clientele) and the degree of CLSC collaboration with other community-based organisations in the planning and delivery of PHP activities were positively associated with the level of diversity, whereas the unemployment rate in the population served was a negative predictor. This study makes an important contribution in being one of the very few which contribute to building our knowledge about the performance of community health centres. Identifying the correlates of diversity among PHP services offered by CLSCs helps us to begin to understand the processes at work in the production of PHP activities, as well as the potential leveraging forces.

Perception of dental illness among persons receiving public assistance in Montreal.

OBJECTIVES: We examined rationales for behaviors related to dental care among persons receiving public assistance in Montreal, Quebec. METHODS: Fifty-seven persons receiving public assistance participated in 8 focus groups conducted in 2002. Sessions were recorded on audiotape and transcribed; analyses included debriefing sessions and coding and interpreting transcribed data. RESULTS: In the absence of dental pain and any visible cavity, persons receiving public assistance believed they were free of dental illness. However, they knew that dental pain signals a pathological process that progressively leads to tooth decay and, therefore, should be treated by a dentist. However, when in pain, despite recognizing that they needed professional treatment, they preferred to wait and suffer because of a fear of painful dental treatments and a reluctance to undertake certain procedures. CONCLUSIONS: Persons receiving public assistance have perceptions about dental health and illness that prevent them from receiving early treatment for tooth decay, which may lead to disagreements with dentists when planning dental treatments.

Dental care pathway of Quebecers after a broken filling.

OBJECTIVES: The objectives were to 1) describe the dental care pathway of adults after sustaining a broken filling, and particularly, the patient delay in seeking care as well as the continuity of care, and 2) identify factors associated with the decisions taken. BASIC RESEARCH DESIGN: In 1998-99, 5,469 Quebec women aged 30 to 44 years completed a self-administered questionnaire in which they indicated whether they had experienced a dental problem in the previous 12 months. From then on, the questions identified the decisions they made during the process of consulting a dentist. RESULTS: 32.4% of the respondents had experienced a dental problem within the last 12 months. Among them, 38.0% reported a broken filling. 65.1% of those who identified a broken filling decided immediately to consult a dentist and 34.9% chose to wait and see. Patient delay was over one month in 44.0% of the cases. When asked by the dentist to come back in order to complete the treatment. 90.6% agreed, 3.2% decided to consult another dentist, and 6.21% chose not to consult. Logistic regression analyses show that patient delay was associated with low income, low degree of inconvenience (symptoms), low degree of perceived seriousness, and absence of a family dentist. CONCLUSIONS: This study reveals important social disparities: after sustaining a broken filling, which remains an important problem in industrialised societies, patient delay, interruption of the dental care episode and extraction are more frequent in low-income groups. It also reveals that a wait-and-see attitude is more frequent than an interruption of the dental care episode after the first visit.

[Breastfeeding promotion and support services in local community health centers]. / Les services de promotion de soutien à l'allaitement maternel en CLSC.

This study had a two-fold goal. First, to document services relating to breastfeeding promotion and support in CLSCs and, second, to examine the links between the delivery of such services and certain organizational and environmental factors. The data were collected in 1999 by means of a self-administered questionnaire sent to all CLSCs in Quebec. The responses indicated that breastfeeding is most often systematically addressed at prenatal meetings and through integrated perinatal programs. CLSCs belonging to a multipurpose establishment are more apt to integrate the issue of breastfeeding into perinatal activities; in addition, many of them offer breastfeeding activities considered innovative, although the average for this kind of activities is fairly low (33%). In addition, CLSCs that collaborate more closely with community organizations and those that spend more on perinatal programs are the ones that most often offer "innovative" breastfeeding activities.

[Utilization of preventive dental services by recent immigrants in Quebec]. / Utilisation des services dentaires de façon préventive par les mères immigrantes au Quèbec.

OBJECTIVES: Studies conducted in Canada show that recent immigrants tend to under-utilize preventive services provided by the health care system. The objective of our study was to learn whether this phenomenon also applies to dental care. METHODS: Our sample was composed of 5,795 women who live in Quebec and are between 30 and 44 years old. These women filled out a self-administered questionnaire regarding their immigration status and their habits concerning dental visits. In our analyses, we compared the use of dental services of recent immigrants (10 years or less in Canada), long-term immigrants (more than 10 years), and non-immigrants (Canadians of origin). RESULTS: 55% of recent immigrants are preventive service users compared to 69% of long-term immigrants and 76% of non-immigrants. The financial barrier partly explains this result: immigrants often have a modest income and rarely benefit from dental coverage. However, having private dental insurance does not in itself explain the gap between these groups. This suggests that there is a cultural barrier in dental services access. CONCLUSIONS: Under-use of preventive services by immigrants is not limited to the medical field, it extends to dental services as well. In order to facilitate immigrants' adaptation to the health system, we recommend that the government provide them with free dental services that respect their culture.