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ORIGINAL ARTICLE
Year : 2016  |  Volume : 5  |  Issue : 3  |  Page : 104-110

Association of dental caries experience with individual and contextual variables in Brazilian children


Department of Preventive and Social Dentistry, Faculty of Dentistry of Piracicaba, State University of Campinas, São Paulo, Brazil

Date of Web Publication26-Aug-2016

Correspondence Address:
Gabriela Christiel Soto Rojas
Avenue Limeira, 901 Areião CP 52 13414 903, São Paulo
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2278-9626.189254

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  Abstract 

Context: There is a trend toward reduction in the caries index in populations of schoolchildren in developed and developing countries. In spite of this reduction, 53.4% Brazilian children present caries experience in primary dentition. Aims: To evaluate the association between dental caries experience in 5-year-old Brazilian and individual and contextual variables. Settings and Design: An analytical cross-sectional study was conducted. Materials and Methods: Data of a national oral health epidemiological survey - SB Brazil 2010 were taken. The outcome studied was caries experience measured by the decayed, missing, and filled teeth (dmft) index. The independent variables were classified into individual (sex, occlusion, treatment need, number of persons' resident in the home, number of bedrooms in the residence, number of goods/assets, and family income) and contextual (family financial aid grand, national health system performance index (Νndice de Desempenho do Sistema Único de Saúde [IDSUS]), Gross National Product, per capita, Human Development Index, and fluoridated water) variables. Statistical Analysis Used: The data were initially analyzed by the Chi-square test, then was applied the multilevel model. Results: Only the contextual variable that evaluates access and quality of public services (IDSUS) was observed to affect the children's dmft index. The individual variables: male sex (P = 0.0005), occlusion (P = 0.0437), dental treatment need (P < 0.0001), number of persons' resident in the home (P < 0.0001), number of bedrooms in the residence (P = 0.0152), number of goods/assets (P = 0.0147), and family income (P = 0.0044) were significant. Conclusions: There is an impact of social determinants on health at individual level but only the IDSUS contextual variable was associated with dmft. Are necessary development public policies to deal with caries with a focus on these determinants?

Keywords: Brazil, dental caries, dental health surveys, multilevel analysis, oral health


How to cite this article:
Brizon VS, Rojas GC, Ambrosano GM, Guerra LM, Pereira AC. Association of dental caries experience with individual and contextual variables in Brazilian children. Eur J Gen Dent 2016;5:104-10

How to cite this URL:
Brizon VS, Rojas GC, Ambrosano GM, Guerra LM, Pereira AC. Association of dental caries experience with individual and contextual variables in Brazilian children. Eur J Gen Dent [serial online] 2016 [cited 2017 Oct 18];5:104-10. Available from: http://www.ejgd.org/text.asp?2016/5/3/104/189254


  Introduction Top


National and international researches have demonstrated a trend toward reduction in the caries index in populations of school children in developed [1] and developing [2] countries. This fact was observed in Brazil through the last two epidemiological studies in which a reduction in decayed, missing, and filled teeth (dmft) was observed for 5-year-old children from of 2.80 in 2003 to 2.43 in 2010. [2],[3] In spite of this reduction, 53.4% Brazilian children present caries experience in primary dentition. [3]

Caries not treated in childhood may prevent the healthy growth and development of the child. This caries disease may lead to suppressed growth due to toothache and reluctance to eat; difficulty in communication with others due to speech disturbances; low self-esteem due to bad breath, and school performance may be deficient due to toothache, interrupted sleep, difficulty in concentration, and lost hours of study time. [4],[5] Studies have shown that the experience of decay during early childhood results in a more severe caries experience during adulthood. Children with primary carious teeth often times exhibit caries in permanent teeth, while children with caries-free primary dentition remain caries-free in the permanent dentition. [6]

Taking into consideration the levels of caries experience, theories have been developed to explain the relationships of modulating factors associated with the phenomenon of the disease. [7] These theories seek to evaluate the influence of individual and contextual risk factors in which the individual is included such as social, income, education, behavioral factors, knowledge, educational level and attitudes, in an endeavor to find an explanation for the causal pathways of the results of oral health, risk behaviors, and the use of oral health services, which may contribute to increase the indices of caries experience, other diseases, and childhood ailments. [8]

Although inequalities in caries experience in children for the different social gradients have been observed in some studies, [9] the contribution of contextual factors to the risk of disease still need to be studied better, particularly in needy populations so that the differences within the social environment may be more clearly elucidated, [10] a fact that justifies new studies.

Therefore, it is important to know the impact of social determinants on health, both at individual and collective level, to contribute to the better direction of the resources of health policies and plan actions to increase the percentages of caries-free children. In view of this scenario, the aim of this study was to identify the indicators of individual and contextual risk for caries experience in 5-year-old Brazilian children.


  Materials and methods Top


The data necessary for elaborating the study were obtained from the epidemiological oral health survey of Brazil (SB Brazil, 2010) [3] in which the oral health conditions of the Brazilian population in different ages groups were analyzed in both urban and rural areas. The project SB Brazil 2010 was approved by the Ethics Committee on Research with Human Beings, Protocol No. 009/2010.

Brazil has a total of 190,755,799 individuals, made up of 2,931,988 5-year-old children. Data were collected from 7348 children in 172 cities in Brazil. [3] The sample design consisted of 32 domains (27 state capitals and 5 domains with reference to cities in the interior of each Brazilian region), and for sample calculation, the dental caries parameters of the national survey conducted in 2003 [2] were used for the respective domains studied.

In this study, the clinical exam was performed and the dmft checked (mean number of decayed, missing (extracted), and filled teeth). The examination was based on the World Health Organization (WHO) criteria. [11]

The field teams formed by an examiner and a note-taker were trained in workshops with duration of 32 h. The capitals had ten field teams and the municipalities in the interior had from 2 to 6 teams, depending on population size. The stages were divided into theoretical discussion, practice, calibration, final discussion, and field strategies.

The calibration technique adopted was consensus, calculating the agreement between each examiner and the results obtained by consensus of the team. The model proposed by the WHO was used as a reference. The pondered kappa coefficient was calculated for each examiner, age group, and disease studied having a value of 0.65 as the minimum acceptable level.

In addition to the traditional indices for verifying oral diseases, data were collected with reference to the following characteristics: (a) Demographic and socioeconomic characterization, (b) use of dental services and oral morbidity reported, and (c) self-perception of and impacts on oral health. The questions were applied to the person responsible for the home to obtain information relative to the family and minors.

The dependent variable studied was caries experience using the dmft (dichotomized as absence/presence).

The independent individual variables included in this study were sex (female/male), dental occlusion (malocclusion/absence of malocclusion: Presence/absence), dental treatment need (caries active/caries free: yes/no), number of persons' resident in the home (1-18), number of bedrooms in the residence (1-18), number of goods/assets (material goods like vehicle, TV, table, others) in the residence (1-11), and monthly family income (up to 250 reais to over Rs. 9,500).

The independent contextual variables relative to the cities were (a) Human Development Index (HDI) of the municipality - MHDI, a measurement that assembles information about longevity, income, and educational level. [12] (b) Family Financial Grant Program ("Bolsa Famνlia" [BF]), which refers to a program of direct income transfer that benefits families living in poverty or extreme poverty and which are composed of pregnant women, nursing mothers, children (between 0 and 12 years of age), and adolescents (up to 15 years old), defined by the criterion of monetary income per capita of below 70 reais per month. This concerns a variable benefit to the monthly value of 32,00 reais per beneficiary up to a limit of Rs. 160,00 per family (approximately 16 million Brazilians - 8.5% of the general population are benefited). [13] For the family financial grant (BF), the number of families benefited per municipality per every 1000 inhabitants were obtained. [13] (c) To evaluate access to and quality of the public oral health services, the National Health Service Performance Index (Νndice de Desempenho do Sistema Ϊnico de Saϊde (IDSUS) was used. IDSUS was launched on March 1, 2012, as a synthesis of 24 indicators that evaluate the performance of SUS, attributing a score (grade) to each municipality, state and Brazil. The score ranges from 0 to 10 in which the lowest scores would represent the worst rankings in the classification relative to the performance of SUS in the State or Municipality considered. In addition to the score, the municipalities are grouped according to the similarity among them, considering the concomitant analysis of three indices Socioeconomic Development (IDSE), Health Conditions (ICS), and Structure of the Municipal Health System (IESSM). These groups are denominated homogeneous and are divided in the following manner: Groups 1 and 2 are formed of municipalities that present the best infrastructure and conditions of service to the population and Groups 3 and 4 have little medium and high complexity structure, while those of Groups 5 and 6 have no structure for specialized attendance/care. [14] For the analysis, the score the municipality received and the number of the homogeneous group in which it was inserted were used. (d) The Municipal Gross National Product (GNP) per capita corresponds the sum of the salaries of the entire population of the municipality, divided by the number of inhabitants in these municipalities. [15] For fluoridated water, the data were dichotomized into municipalities with the presence or absence of fluoride in the water for consumption. [15]

Statistical analysis

The data were initially analyzed by the Chi-square test. For the multilevel model, the data were analyzed using fixed components represented by the variables studied and random components, represented by the cities and by variances in the different levels. Adjustments to the model were made by the PROC MIXED procedure of the statistical software program Statistical Analysis System (SAS) 9.2, 2008. In Level 1, the variables relative to individuals were considered. In Level 2, the variables relative to cities, with the dmft (Level 1) being evaluated as a function of the predictive variables of Levels 1 and 2. A model was initially adjusted only with the intercept (Model 1). After this, the predictive effects of the level of individuals (Level 1) were included - Model 2 and of the cities (Level 2) - Model 3. In the selection of the contextual variables, the indicators related to access to and quality of health services (IDSUS), socioeconomic conditions (HDI and GNP per capita), and social vulnerability (Family Financial Grant [BF]) were taken into consideration. The quality of the adjustments was evaluated by the convergence of the model, AIC, AICC, and statistical criteria - 2 times the logarithm of the function of vero similarity. In all the analyses, a level of significance of 5% was used.


  Results Top


Descriptive analysis of the independent variables (frequency and percentage) may be observed in [Table 1] and [Table 2]. The largest portion of the subjects examined (76.13%) lived in the capitals, while there was a balance between the two sexes. Approximately, half the individuals (49.05%) had some treatment need [Table 1]. Seventy-five percent of those examined came from families with a monthly income of up to Rs. 150,000 and 70% resided in homes with 1-3 rooms [Table 2].
Table 1: Frequency and percentage of 5 - year - old children, according to qualitative independent variables Brazil, 2011

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Table 2: Frequency and percentage of 5 - year - old children, according to number of bedrooms, goods, and family income Brazil, 2011

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In [Table 3], it was verified that on an average, the cities from which the participants came had 55.51 families benefited by the Family Financial Grant program (BF) per every 1000 inhabitants, the IDSUS was 5.64; GNP per capita of 17329.76 reais, and HDI of 0.79.
Table 3: Frequency, percentage of 5-year-old children favored by fluoridated water and mean and standard deviation of contextual variables Brazil, 2011

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In [Table 4], the different estimated multilevel models are presented. In Model 1, it may be observed that the mean dmft score in the cities of the sample was 2.93, with the standard error of 0.11. Furthermore, it was observed that the variation in the caries index among cities was significant (P < 0.0001); however, the variation among the volunteers in the same city was around 7 times higher than the variation among the cities. By the intraclass correlation, it could be affirmed that the variation between the cities represented approximately 12% of the total variation. When the variables of the individual level (Model 2) were included, it was observed that they presented a higher dmft of individuals of the male sex (P = 0.0002), with treatment need (P < 0.0001), with a higher number of persons' resident in the home (P < 0.0001), lower number of bedrooms in the residence (P = 0.0204), lower number of goods/assets (P = 0.0059), and lower family income (P = 0.0015). In Model 3, the variables of the second level (cities) were included to evaluate the influence of these in the explanation of the variability of dmft. It was observed that only the variable that evaluates access to and quality of the public health services (IDSUS) affected the dmft. The following variables continued to be significant in caries experience: male sex (P = 0.0005), occlusion (P = 0.0437), dental treatment need (P < 0.0001), number of persons' resident in the home (P < 0.0001), number of bedrooms in the residence (P = 0.0152), number of goods/assets (P = 0.0147), and family income (P = 0.0044).

In all the models, the significances were controlled by the other predictors of the model.
Table 4: Multilevel analysis for individual and contextual variables for the decayed, missing filled teeth of 5-year-old children Brazil, 2011

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  Discussion Top


The results obtained in the present study showed the evidence of an association of the individual level variable with caries experience in 5-year-old children. The male sex presented the highest dmft index in comparison with the female sex, which corroborates the results of the research, which evaluated the pattern of caries prevalence in primary dentition in 5-year-old schoolchildren, showing higher prevalence of boys with caries (47.4%) than in girls (41.1%), [16] and demonstrating that girls are more conscious of their diet, oral health, and hygiene. [17] Moreover, another study of assessment of caries prevalence among children below 5 years old shows that caries experience was higher in boys (47.44%) than in girls (40.94%). This difference was statistically significant. [18]

A higher dmft index was observed in children with greater treatment need and with a higher number of persons' resident in the home. The result of a study that associated the factors related to caries in preschool children is consistent with those of this national research as it verified that only the existence of three or more siblings living in the same house was a predictor of caries in this age group. This is a finding that is also consistent with those of studies that have indicated lower risk for caries among children who did not have siblings or a lower number of them. [19],[20] There are reports linking the higher number of siblings to increased dental caries experience in young children. The number of siblings is a crucial factor in caries prevalence in the primary dentition. [21] This probably points in the direction of the parents' attention, especially the mother's, who generally is the caregiver and who spends more time with the child. The higher the number of children, the greater the demand, and consequently, the division of care and time spent on each child.

Children who reside in houses with a lower number of bedrooms in the residence, lower number of goods/assets, and lower family income presented a higher dmft index. The conditions of social and material disadvantages to which individuals are exposed may be expressed in terms of greater susceptibility to caries, contributing to the worst oral health conditions. [22] Family agglomeration and socioeconomic status have been associated with caries, clearly expressing the fact that social privation acts as a strong indicator of risk to oral health conditions. [9],[23] Epidemiological data obtained from samples composed of subjects with different socioeconomic statuses have revealed that the presence of early childhood caries was strongly related to families with a low socioeconomic level because families with a low social level have material, social, and financial disadvantages that compromise their ability to care for their own health and that of their children. These families have difficulty in obtaining professional healthcare and do not identify dental problems, leaving out preventive care during the initial stages of the disease. [24]

Moreover, in the present study, the cities with a larger number of families grouped in Groups 5 and 6, in which access to and quality of public services are compromised because they do not have any structure for specialized care and attention and were associated with caries experience. This demonstrates that the impacts of the inequalities in the health profile of the difference social groups are diverse and have been problematized in different countries in the world. Diverse studies have sought to understand how socioeconomic, regional, and sexual inequalities produce an impact on the morbimortality profile of the population and on access to and use of health services. [2],[3],[9]

In conceptual models, the health behaviors and use of oral health services are considered proximal factors for the results of oral health [25],[26] having a greater influence on the socially more vulnerable groups. Health is affected by the psychosocial/stress medium and is directly or indirectly modulated by the individual's behavior. [27] Thus, we could observe lower topical exposure to fluoridated toothpaste and a worse profile of dental cleanliness resulting in higher levels of dental caries. [8],[9]

It was observed no association between fluoridated water and dmft index. Because it is an ecological study addressing only some municipalities, it could have caused a fallacy of the study because as has been proven, the presence of fluoride in the water has a significant impact on prevention of dental caries. [5] In Brazil, despite being mandatory fluoridation of the waters, many municipalities have operational problems to do this. For this reason, the supply of fluoridated waters for the entire population is difficult. In the epidemiological survey SB Brazil 2010, cities were chosen by draw into 5 clusters and the power of association has been not strong enough to support the relation between these variables.

However, the results achieved in this study must be analyzed with care, bearing in mind the inherent limitations to the cross-sectional study design adopted, by the difficulty in establishing causal relationships based on a cross-section in time, limiting the confidence in the establishment of the direction of the association.

Furthermore, it should be pointed out that the option for multilevel analysis arose from the fact of the importance of investigating interactions among variables of different levels (individual and contextual). Therefore, greater statistical efficacy, greater power, and less bias are verified than those contained in a multiple analysis such as logistic regression. [28] This information is useful for backing other researchers and for understanding the influence of the individual and contextual variables on caries experience. In general, the information produced in this study expresses the accumulation of a series of problems that have not been faced, showing evidence of inequalities in health. For an intentional change, integrated health actions, common to those of other childhood diseases, are indicated at diverse levels of the health system. [29] These actions combine programmed intersectoral actions, for example, the Health Program at School (PSE). Its implementation in preschools is of great importance because it units the efforts of the health sector with those of the education sector. [30]

For a reduction in inequalities in health to occur, there must be a greater focus of attention on the less favored groups because reducing inequalities in health is equivalent to working for a more equitable society. The actions must be based on knowledge of and fall on the determinants on health, and the indicators of risk for caries must be identified, considering individual variables in conjunction with contextual variables, which may differ, according to the diverse socioeconomic groups.


  Conclusion Top


The present study demonstrated the impact of social determinants on health both at individual and collective level. Therefore, there was a clear need for public policies to deal with caries in 5-year-old children, with focus on individuals of the male sex, aspects connected with occlusion, dental treatment needs, number of persons' resident in the home and the number of bedrooms and goods/assets in the residence, as well as family income. As regards the contextual determinants, the condition of access to and quality of public health service provided by the municipality must be a factor of relevance in the construction of the mentioned policies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
World Health Organization. The World Oral Health Report 2003. Continuous Improvement of Oral Health in the 21 st Century - The Approach of the WHO Global Oral Health Programme. Geneva: World Health Organization; 2003.  Back to cited text no. 1
    
2.
Brazil. Ministry of Health Secretariat of Health Care Project SB Brazil 2003: Oral health status of the population from 2002 to 2003. Main results. Brasilia: Ministry of Health; 2004.  Back to cited text no. 2
    
3.
Brazil. Ministry of Health. Secretariat of Health Surveillance. Department of Health Care. National Oral Health Coordination. SB 2010 National Oral Health Survey. Main results. Brasilia: MS; 2011.  Back to cited text no. 3
    
4.
Santamaria RM, Basner R, Schuler E, Splieth CH. Inequalities in dental caries experience among 6-year-old German children after the caries decline. Acta Odontol Scand 2015;73:285-91.  Back to cited text no. 4
    
5.
Plutzer K, Spencer AJ. Efficacy of an oral health promotion intervention in the prevention of early childhood caries. Community Dent Oral Epidemiol 2008;36:335-46.  Back to cited text no. 5
    
6.
Jordan AR, Becker N, Jöhren HP, Zimmer S. Early childhood caries and caries experience in permanent dentition: A 15-year cohort study. Swiss Dent J 2016;126:114-9.  Back to cited text no. 6
    
7.
Sisson KL. Theoretical explanations for social inequalities in oral health. Community Dent Oral Epidemiol 2007;35:81-8.  Back to cited text no. 7
    
8.
Cortellazzi KL, Pereira SM, Tagliaferro EP, Tengan C, Ambrosano GM, Meneghim Mde C, et al. Risk indicators of dental caries in 5-year-old Brazilian children. Community Dent Health 2008;25:253-6.  Back to cited text no. 8
    
9.
Polk DE, Weyant RJ, Manz MC. Socioeconomic factors in adolescents′ oral health: Are they mediated by oral hygiene behaviors or preventive interventions? Community Dent Oral Epidemiol 2010;38:1-9.  Back to cited text no. 9
    
10.
Reisine ST, Psoter W. Socioeconomic status and selected behavioral determinants as risk factors for dental caries. J Dent Educ 2001;65:1009-16.  Back to cited text no. 10
    
11.
WHO. Health Through Oral Health: Guidelines for Planning and Monitoring for Oral Health Care. World Health Organization and Federation Dentaire Internationale. London: Quintessence; 1989.  Back to cited text no. 11
    
12.
Programa das Nações Unidas para o Desenvolvimento - PNUD. Índice de Desenvolvimento Humano (IDH); 2012. Available from: http://www.pnud.org.br/idh/. [Last accessed on 2015 Sep 30].  Back to cited text no. 12
    
13.
Ministry of Social Development and Fight against Hunger (MDS). Family Financial Grant Program: MDS; 2012.  Back to cited text no. 13
    
14.
Brazil. Ministry of Health IDSUS - Performance Index Health System; 2011.  Back to cited text no. 14
    
15.
The Brazilian Institute of Geography and Statistics (BR). National survey by sample households: Access to and use of health services. Rio de Janeiro; 2010.  Back to cited text no. 15
    
16.
Saravanan S, Madivanan I, Subashini B, Felix JW. Prevalence pattern of dental caries in the primary dentition among school children. Indian J Dent Res 2005;16:140-6.  Back to cited text no. 16
[PUBMED]  Medknow Journal  
17.
Charani A, Mohsin S, Sufia S, Khan AA. Prevalence of early childhood caries among 3-5-year old children of Clifton, Karachi. J Pak Dent Assoc 2011;20:89-92.  Back to cited text no. 17
    
18.
Prabhu P, Rajajee KT, Sudheer KA, Jesudass G. Assessment of caries prevalence among children below 5 years old. J Int Soc Prev Community Dent 2014;4:40-3.  Back to cited text no. 18
    
19.
Schou L, Uitenbroek D. Social and behavioural indicators of caries experience in 5-year-old children. Community Dent Oral Epidemiol 1995;23:276-81.  Back to cited text no. 19
    
20.
Oliveira LB, Sheiham A, Bönecker M. Exploring the association of dental caries with social factors and nutritional status in Brazilian preschool children. Eur J Oral Sci 2008;116:37-43.  Back to cited text no. 20
    
21.
Sujlana A, Pannu PK. Family related factors associated with caries prevalence in the primary dentition of five-year-old children. J Indian Soc Pedod Prev Dent 2015;33:83-7.  Back to cited text no. 21
[PUBMED]  Medknow Journal  
22.
Mattheus DJ. Vulnerability related to oral health in early childhood: A concept analysis. J Adv Nurs 2010;66:2116-25.  Back to cited text no. 22
    
23.
Lisboa CM, de Paula JS, Ambrosano GM, Pereira AC, Meneghim Mde C, Cortellazzi KL, et al. Socioeconomic and family influences on dental treatment needs among Brazilian underprivileged schoolchildren participating in a dental health program. BMC Oral Health 2013;13:56.  Back to cited text no. 23
    
24.
Borges HC, Garbín CA, Saliba O, Saliba NA, Moimaz SA. Socio-behavioral factors influence prevalence and severity of dental caries in children with primary dentition. Braz Oral Res 2012;26:564-70.  Back to cited text no. 24
    
25.
Sanders AE, Slade GD, Turrell G, John Spencer A, Marcenes W. The shape of the socioeconomic-oral health gradient: Implications for theoretical explanations. Community Dent Oral Epidemiol 2006;34:310-9.  Back to cited text no. 25
    
26.
Perera I, Ekanayake L. Influence of oral health-related behaviours on income inequalities in oral health among adolescents. Community Dent Oral Epidemiol 2011;39:345-51.  Back to cited text no. 26
    
27.
Bernabé E, Hobdell MH. Is income inequality related to childhood dental caries in rich countries? J Am Dent Assoc 2010;141:143-9.  Back to cited text no. 27
    
28.
Hox JJ. Multilevel Analysis: Techniques and Applications. Mahwah: Lawrence Erlbaum Associates, Routledge; 2002.  Back to cited text no. 28
    
29.
Watt RG. Social determinants of oral health inequalities: Implications for action. Community Dent Oral Epidemiol 2012;40 Suppl 2:44-8.  Back to cited text no. 29
    
30.
Buischi YA, Axelsson P, Oliveira LB, Mayer MP, Gjermo P. Effect of two preventive programs on oral health knowledge and habits among Brazilian schoolchildren. Community Dent Oral Epidemiol 1994;22:41-6.  Back to cited text no. 30
    



 
 
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