SciELO - Scientific Electronic Library Online

vol.31 número1El efecto del envejecimiento gingival en el estado diabetico y no diabetico: Estudio experimentalFactores asociados con la presencia de sobreobturación apical posterior a una técnica de obturación termoplástica Calamus® o Guttacore®: experimento clínico aleatorizado índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados




  • Não possue artigos citadosCitado por SciELO

Links relacionados

  • Não possue artigos similaresSimilares em SciELO


Acta Odontológica Latinoamericana

versão On-line ISSN 1852-4834

Acta odontol. latinoam. vol.31 no.1 Buenos Aires abr. 2018



Oral health-related quality of life in Colombian children with Molar-Incisor Hypomineralization

Calidad de vida relacionada con la salud oral en niños Colombianos con Hipomineralización Inciso- Molar


Lina M. Velandia1, Laura V. Álvarez1, Lofthy P. Mejía1, Martha J. Rodríguez2

1 Universidad Santo Tomás, Facultad de Odontología, Área de Odontopediatría, Colombia.
2 Universidad Santo Tomás, Facultad de Odontología, Área de Investigación, Colombia.



The aim of this study was to assess the impact of Molar-Incisor Hypomineralization (MIH) on Oral Health-Related Quality of Life (OHRQoL) in schoolchildren from a public educational institution in Bucaramanga, Colombia. Eighty-eight 7- to 10-year-olds took part in the study; of whom half had MIH. The translated and adapted version of the Child Perceptions Questionnaire (CPQ 8-10) was applied by means of an interview. The dependent variable was OHRQoL and explanatory variables were presence and severity of MIH, sex, age, socioeconomic status and social security. Frequencies and proportions were calculated for qualitative variables, and measures of central tendency, dispersion and position were calculated for quantitative variables. Chi-square, Fisher's Exact Test, Mann-Whitney U Test and Kruskal-Wallis tests were used, as appropriate. A p-value <0.05 was considered statistically significant. Parents or caregivers of participating children signed informed consent, and children signed an assent. A statistically significant difference was found for age groups (p<0.001), socioeconomic status (p=0.015) and social security (p=0.045) according to the presence of MIH. Likewise, statistically significant differences were found for each of the four domains of the questionnaire and for the overall CPQ 810 score (p<0.0001) according to the presence of MIH. The presence of the Molar-Incisor Hypomineralization may have negative impact on the Oral Health-Related Quality of Life of the participating children.

Key words: Quality of Life; Dental enamel hypoplasia; Oral health; Tooth demineralization.


El objetivo de este trabajo fue evaluar el impacto de la Hipomineralización Inciso Molar sobre la Calidad de Vida Relacionada con la Salud Oral (CVRSO) en escolares vinculados con una institución educativa pública de Bucaramanga, Colombia. Ochenta y ocho menores de 7 a 10 años hicieron parte del estudio, la mitad presentaba HIM; a todos se les aplicó la versión traducida y adaptada del Child Perceptions Questionnaire (CPQ 8-10) mediante entrevista. La variable de salida fue la CVRSO y las variables explicatorias, la presencia y severidad de HIM, el género, la edad, el estrato socioeconómico y la seguridad social. Se calcularon frecuencias y proporciones para las variables cualitativas, y medidas de tendencia central, dispersión y posición para las cuantitativas. Se utilizaron las pruebas Chi2, Test Exacto de Fisher, U. de Mann Whitney y Kruskal-Wallis según fuera apropiado. Un valor de p<0,05 fue considerado estadísticamente significativo. Los padres o cuidadores de los menores participantes firmaron un consentimiento informado y los niños y niñas, un asentimiento. Se encontró una diferencia estadísticamente significativa en los grupos de edad (p<0,001), el estrato socioeconómico (p=0,015), y la seguridad social (p=0,045) según la presencia de HIM. Así mismo, se obtuvo una diferencia estadísticamente significativa en cada uno de los cuatro dominios del cuestionario y en el puntaje global del CPQ 8-10 (p<0,0001) de acuerdo con la presencia de HIM. Según las percepciones de los participantes al responder al CPQ 8-10, se podría sugerir la presencia de la Hipomineralización Inciso Molar influye de forma negativa sobre la Calidad de Vida Relacionada con la Salud Oral en los niños participantes.

Palabras clave: Calidad de vida; Hipoplasia del esmalte dental; Salud bucal; Desmineralización dental.



Quality of Life (QoL) is defined as the perception of wellbeing and subjective, personal manifestation of feeling well within the cultural and social context in which one lives. According to the World Health Organization (WHO) it is influenced in a complex way by physical health, psychological status, social relationships and relationship with essential elements in the environment, among others1. Oral health also affects QoL, with major impact on physical, psychological and social aspects. This is especially true for children, who are undergoing physical, mental and social growth, which is why some papers claim that oral diseases can have negative impact on children's QoL, in contrast to children who do not have any oral pathology2,3.

Developmental Defects of Enamel (DDE) have been reported to impact QoL because they affect both aesthetics and function. These effects include Molar-Incisor Hypomineralization (MIH), defined as a hypomineralized lesion of the enamel as a result of different causes, mainly affecting permanent first molars and frequently associated to similar lesions on upper and/or lower permanent incisors, which causes deterioration and destruction of affected teeth because the enamel is fragile, and depending on the severity, may cause teeth to be lost4,5. MIH on permanent incisors compromises aesthetics and MIH on first molars alters the eruption guide for other molars, and hence, occlusion4,6.

Masticatory function is also altered, since depending on how severely the enamel is affected and the forces applied during mastication, dental wear and fractures may cause dentin to be exposed, with subsequent tooth sensitivity7. This leads to the child brushing their teeth less and thereby having inappropriate hygiene, leading to greater susceptibility to carious lesions and increasing deterioration of affected teeth8,9. MIH also creates a dental clinical problem because it is difficult to eliminate dental sensitivity, and it causes marginal degradation of restorations due to lack of adequate adhesion between tooth structure and restorative material4,10.

In 2003, Weerheijm et al. proposed the criteria used by the European Academy of Paediatric Dentistry (EAPD), identifying lesions according to: presence or absence of demarcated opacity, posteruptive breakdown, atypical restoration, premature extraction of first molars due to MIH, failure of eruption of a molar or incisor11. In 2006, Mathu-Mujuy and Wright12 classified MIH as mild, moderate or severe. Many other classifications have been developed considering the severity, size, depth and extent of hypomineralization13. This lack of uniformity for diagnosing the lesion has meant that the results of studies are not consistent and not comparable epidemiologically 6. Considering this situation, reports on prevalence of MIH differ widely among populations. Table 1 shows the values reported in some studies7,14-22.

Table 1: Evaluation criteria and prevalence of MIH.

As mentioned above, MIH affects Oral Health-Related Quality of Life (OHRQoL). Dantas-Neta et al. (2016) evaluated perception of OHRQoL in 594 schoolchildren and their parents by applying the Child Perceptions Questionnaire (CPQ 11-14) and the Parental-Caregiver Perceptions Questionnaire (P-CPQ). They found that there was a negative impact in the domains of "oral symptoms"[RR 1.30 CI 95% 1.06-1.60] and "functional limitation"[RR 1.42 CI 95% 1.08-1.86] in schoolchildren with severe MIH compared to those without MIH23. Arrow applied the Parental Perceptions Questionnaire (PPQ) to parents of 522 children and found no association between OHRQoL and Developmental Defects of Enamel (DDE) in first permanent molars24. In this regard, it is important to mention that Arrow did not discriminate these defects in MIH and that it is not a good idea to use parents' answers as a proxy because their view may be based on external factors unrelated to what the child feels25.

Since few studies have been published on the influence of Molar-Incisor Hypomineralization on Oral Health-Related Quality of Life in children, the aim of this study was to evaluate this relationship by applying the Colombian version of the Child Perceptions Questionnaire (CPQ 8-10) to children attending a public school in the city of Bucaramanga (Colombia).


An analytical observational cross-sectional study was performed, with non-probability sampling of 88 7 to 10 year-old schoolchildren from a public educational institution in the city of Bucaramanga. Bucaramanga is the capital of the department of Santander, located in north-east Colombia, and considered in the July-September 2016 quarter to be the city with lowest unemployment in the country26.

The sample was calculated using the OpenEpi software version 3.1 with 97% confidence and 5% type I error based on a population of 928 students, and expected prevalence of 5.4% according to a study performed in the city of Medellin (Colombia) 27,28. Participants were selected by convenience sampling to ensure equitable, proportional representation, with half the sample with MIH and the other half without MIH. Schoolchildren in this age range (7 to 10 years) were included because their permanent first molars and incisors have erupted. Children with systemic compromise, physical or mental disability, severe malocclusions, presence of fixed orthodontic appliances, teeth with cavities, fillings in first molars and incisors, and teeth with enamel developmental defects other than MIH (enamel fluorosis, amelogenesis imperfect) were excluded.

Output variable was Oral Health-Related Quality of Life evaluated by the CPQ 8-10. Explanatory variables were presence and severity of MIH, sex, socioeconomic level (tool to classify housing according to the National Statistics Administrative Department in Colombia) and type of social security.

Clinical examination

Dental clinical examination was performed at the school nurse's office by an examiner previously calibrated by an expert (Cohen's Kappa coefficient = 0.68). Children brushed their teeth, after which presence/absence (yes/no) of MIH and its severity were evaluated following the criteria of Mathu-Muju and Wright12. MIH was considered present when at least one affected molar was found according to the guidelines proposed by the EAPD11. It is important to note that dental hypersensitivity was not investigated. Inspection was performed using mouth mirror, gauze for drying, tongue depressor and very good lighting. Children without MIH were selected as controls.

Evaluation of Oral Health-Related Quality of Life

The version of the Child Perceptions Questionnaire (CPQ 8-10) created by Jokovic et al. 29,30and translated and adapted to Colombian Spanish was used. It consists of 25 questions divided into four domains: "oral symptoms" (five items), "functional limitation" (five items), "emotional wellbeing" (five items) and "social wellbeing" (10 items). Answer options are arranged on a Likert scale with five categories: 0 = never, 1 = once or twice, 2 = sometimes, 3 = often, and 4 = nearly every day. The CPQ 8-10 was applied in an interview. The closer the score was to zero, the better oral health-related quality of life was considered to exist.

In addition, socio-demographic information was collected by means of a questionnaire sent to children's parents or caregivers.

Statistical analysis

The information collected was entered in duplicate to an Excel database to be validated subsequently in EpiData 3.1. The fully refined database was exported to the Stata IC 12.0 statistical package31-33. Univariate analysis was used to calculate central tendency values and dispersion for quantitative variables. Frequency tables were made for categorical variables. Bivariate analysis was used to analyze presence of MIH with relation to sex, age, socioeconomic status and social security by means of Chi-square or Fisher's exact test. The distribution of each domain in the questionnaire was reviewed and the mean score for each domain and total questionnaire score were calculated to be associated with presence of MIH and sex using Mann-Whitney's test. The Kruskal-Wallis test was used to establish association between questionnaire domains and MIH degree of severity. A value of p<0.05 was considered statistically significant.

Ethical considerations

This study was classified as "research with minimum risk" according to Resolution 8430 of October 1993 which establishes the scientific, technical and administrative standards for health research in Colombia34. In addition, it was approved by the Research Ethics Committee of Universidad Santo Tomás. Authorization was requested from the school, and participants' parents signed an informed consent after receiving an explanation of the aim and procedure of the study. Children were asked for assent to participate. The principles of autonomy, beneficence, justice and non-maleficence were observed.


Half of the 88 children in the sample had MIH. Forty-seven (47; 53.4%) were female. Average age was 8.6 ± 1.2 years[CI 95% 8.4-8.9]. Average age was 8.8 ± 1.2 years for males and 8.5 ± 1.1 years for females; with no statistically significant difference for age according to sex (p=0.3167). Table 2 shows the demographics of the study population according to presence of MIH. A statistically significant difference (p<0.001) was found according to age group, with a higher proportion of 7- to 8-year-olds having MIH.

Table 2: Sample demographics according to presence of MIH (n=88).

Average CPQ 8-10 score for participants with MIH was17.4 ± 14.1[CI 95% 13.1-21.7] (Median = 12.5),ranging from 2 to 57. Average overall score for the questionnaire in children without MIH was 4.3 ± 4.1[CI 95% 3.1-5.6] (Median = 4.0), ranging from 0 to 22. There was a statistically significant difference between groups (p<0.0001).

Table 3 shows Median (Me) and Interquartile Range (IQR) for the scores in each dimension and for the overall questionnaire according to presence of MIH. Median score was 2.0 or higher for all domains when children had MIH.

Table 3: Median and interquartile range for scores in each domain and full questionnaire according to presence of MIH.

Median score for the full questionnaire according to presence of MIH and sex was higher in females, regardless of presence of MIH. However, the difference was not statistically significant (Fig. 1). For MIH severity, 24 (54.6%) of the children had moderate severity (demarcated opacities on the occlusal/incisal third without breakdown, posteruptive loss of enamel or carious lesions limited to one or two zones, without participation of cusps). There were 16 (33.4%) cases of isolated opacities without loss of dentin in these areas (mild). There was no statistically significant difference in CPQ 810 scores according to severity (p=0.4420) (Table 4).

Fig. 1: Mean and interquartile range for CPQ 810 scores according to presence of MIH and sex.


Presence of Molar-Incisor Hypomineralization affected Oral Health-Related Quality of Life in the children who participated in the study. This is in agreement with Oyedele et al. 8 who report that children with MIH presented a series of associated entities such as dental caries, dentin hypersensitivity and aesthetic compromise, which have a negative influence on OHRQoL.

Dantas-Neta et al. report that severe MIH was found to have a negative impact on OHRQoL when the Child Perceptions Questionnaire (CPQ 11-14) was applied to a population of 594 11- to 14-year-old schoolchildren; with Risk Ratio (RR) 1.30[CI 95% 1.06-1.60] in the domain "oral symptoms" and RR 1.42[CI 95% 1.08-1.86] in the domain "functional limitation"23. It is important to note that participant age was higher in that study than in ours, considering that it has been suggested that untreated MIH worsens with age due to plaque accumulation, hypersensitivity, enamel breakdown and dental caries4. Vargas-Ferreira and Ardenghi35 also found association between the dimension "functional limitation" in CPQ 11-14 and enamel defects. In contrast, Arrow36 applied the CPQ 11-14 to children with enamel defects in first molars and found no effect on OHRQoL, although there was association with presence of dental caries. We found that MIH affected females more than males, considering that the CPQ 8-10 score were higher for females. This has also been reported by other authors23,37. Girls are considered to be more concerned with their personal appearance and self-perception36. Socioeconomic status and type of social security revealed a statistically significant difference between participants with and without MIH. A higher proportion of children with MIH had low socioeconomic status and used the social security system subsidized by the Colombian State. Dantas-Neta et al23 related low socioeconomic status with children's difficulty to access to oral hygiene products and information, as well as timely dental care, with a negative impact on Oral Health-Related Quality of Life. These variables are therefore considered to be confounding because they are directly related to the OHRQoL, as reported. As mentioned above, one of the difficulties in comparing results is the variation in methods used to identify hypomineralization, as it is included in the Defects in Development of Enamel (DDE) classification38-40. In addition, there is influence of age difference between populations evaluated, the ways in which clinical examination is performed, and recording methods6. It should be noted that the European Academy of Paediatric Dentistry suggests taking into account its recommendations to determine presence of MIH11.

In participants with MIH, severity did not differ statistically between groups with relation to the four domains of the questionnaire and overall score, possibly because very few participants (less than 10%) presented degree of severity 3. Nevertheless, the median score for the whole questionnaire for this group was slightly lower than the score for the group with severity 2 (Me=14.0 vs. Me=15.5).

This study has some limitations. Participants were selected for convenience, so the results found cannot be generalized. In addition, the population study was from a public educational institution that did not include all socioeconomic levels, and participation of children with dental caries lesions was restricted. Among the strengths of the study, it is one of the few studies evaluating OHRQoL in children with MIH. Moreover, the clinical examination was performed carefully by a calibrated examiner, and children's age was appropriate for evaluation of MIH6. According to the results, it may be concluded that presence of MIH in 7- to 10-year-olds has negative impact on all dimensions of OHRQoL as reflected by the CPQ 8-10.


We thank the children who took part, their parents and/or caregivers and the school that allowed this study to be conducted at its facilities.


Mg. Martha Juliana Rodriguez
Universidad Santo Tomás, Facultad de Odontología, 3°p Ed Santander Km. 6 vía a Piedecuesta (Campus Floridablanca), Floridablanca, Santander, Colombia.


1. Fayers PM, Machin D. Quality of Life: The assessment, analysis and interpretation of patien-reported outcomes. Great Britain Second ed. : Wiley, 2007.         [ Links ]

2. Castro F, Raggio D, Imparato J, Piovesan C, et al. Impacto dos problemas bucais emqualidade de vida em pre-escolares. Pesq Bras Odontoped Clin Integr, Joao Pessoa 2013; 13:361369.         [ Links ]

3. Barbosa TS, Gaviao MB. Oral health-related quality of life in children: part II. Effects of clinical oral health status. A systematic review. Int J Dent Hyg 2008; 6:100-107.         [ Links ]

4. William V, Messer LB, Burrow MF. Molar incisor hypomineralization: review and recommendations for clinical management. Pediatr Dent 2006;28:224-232.         [ Links ]

5. Silva MJ, Scurrah KJ, Craig JM, Manton DJ, et al. Etiology of molar incisor hypomineralization - A systematic review. Community Dent Oral Epidemiol 2016; 44:342-353.         [ Links ]

6. Jalevik B. Prevalence and diagnosis of Molar-Incisor-Hypomineralisation (MIH): a systematic review. Eur Arch Paediatr Dent 2010; 11:59-64.         [ Links ]

7. da Costa-Silva CM, Jeremias F, de Souza JF, Cordeiro RdeC, et al. Molar incisor hypomineralization: prevalence, severity and clinical consequences in Brazilian children. Int J Paediatr Dent 2010; 20:426-434.         [ Links ]

8. Oyedele TA, Folayan MO, Adekoya-Sofowora CA, Oziegbe EO. Co-morbidities associated with molar-incisor hypomineralisation in 8 to 16 year old pupils in Ile-Ife, Nigeria. BMC Oral Health 2015; 15:37.         [ Links ]

9. Americano GC, Jacobsen PE, Soviero VM, Haubek D. A systematic review on the association between molar incisor hypomineralization and dental caries. Int J Paediatr Dent 2017; 27:11-21.         [ Links ]

10. Elhennawy K, Schwendicke F. Managing molar-incisor hypomineralization: A systematic review. J Dent 2016; 55:16-24.         [ Links ]

11. Weerheijm KL, Duggal M, Mejare I, Papagiannoulis L, et al. Judgement criteria for molar incisor hypomineralisation (MIH) in epidemiologic studies: a summary of the European meeting on MIH held in Athens, 2003. Eur J Paediatr Dent 2003; 4:110-113.         [ Links ]

12. Mathu-Muju K, Wright JT. Diagnosis and treatment of molar incisor hypomineralization. Compend Contin Educ Dent 2006; 27:604-610.         [ Links ]

13. Allam E, Ghoneima A, Kula K. Definition and scoring system of molar incisor hypomineralization: a review. Dent Oral Craniofac Res 2017; 3:1-9.         [ Links ]

14. Murrieta-Pruneda JF, Torres-Vargas J, Sánchez-Meza JDC. Frecuencia y severidad de hipomineralizacion incisivo molar (HIM) en un grupo de ninos mexicanos, 2014. Rev Nac Odontol 2016; 12:7-14.         [ Links ]

15. Escobar A, Mejia J, Castaño J, González S, et al. Prevalencia y severidad de la hipomineralización molar-incisivo (HMI) en pacientes escolarizados de la ciudad de Medellin. Repositorio Digital Universidad CES. 2015. URL:        [ Links ]

16. Oyedele TA, Folayan MO, Adekoya-Sofowora CA, Oziegbe EO, et al. Prevalence, pattern and severity of molar incisor hypomineralisation in 8- to 10-year-old school children in Ile-Ife, Nigeria. Eur Arch Paediatr Dent 2015; 16:277-282. URL:         [ Links ]

17. Ng JJ, Eu OC, Nair R, Hong CH. Prevalence of molar incisor hypomineralization (MIH) in Singaporean children. Int J Paediatr Dent. 2015; 25:73-8.         [ Links ]

18. Lima MdeD, Andrade MJ, Dantas-Neta NB, Andrade NS, et al. Epidemiologic study of Molar-incisor Hypomineralization in schoolchildren in North-eastern Brazil. Pediatr Dent 2015; 37:513-519.         [ Links ]

19. Bhaskar SA, Hedge S. Molar-incisor hypomineralization: prevalence, severity and clinical characteristics in 8- to 13-year-old children of Udaipur, India. J Indian Soc Pedod Prev Dent 2014; 32:322-329.         [ Links ]

20. Garcia-Margarit M, Catala-Pizarro M, Montiel-Company JM, Almerich-Silla JM. Epidemiologic study of molar-incisor hypomineralization in 8-year-old Spanish children. Int J Paediatr Dent 2014; 24:14-22.         [ Links ]

21. Biondi AM, Cortese SG, Martinez K, Ortolani AM, et al. Prevalence of molar incisor hypomineralization in the city of Buenos Aires. Acta Odontol Latinoam 2011;24: 81-85.         [ Links ]

22. Calderara PC, Gerthoux PM, Mocarelli P, Lukinmaa PL, et al. The prevalence of Molar Incisor Hypomineralization (MIH) in a group of Italian School children. Eur J Pediatr Dent 2005; 6:79-83.         [ Links ]

23. Dantas-Neta NB, Moura LF, Cruz PF, Moura MS, et al. Impact of molar-incisor hypomineralization on oral health-related quality of life in schoolchildren. Braz Oral Res 2016; 30:e117.         [ Links ]

24. Arrow P. Child oral health-related quality of life (COHQoL), enamel defects of the first permanent molars and caries experience among children in Western Australia. Community Dent Health 2013; 30:183-188.         [ Links ]

25. Eiser C, Morse R. A review of measures of quality of life for children with chronic illness. Arch Dis Child 2001; 84:205-211.         [ Links ]

26. Bucaramanga: ciudad con menor desempleo en Colombia Revista Semana; 2016. URL:        [ Links ]

27. Dean A, Sullivan K, Soe M. OpenEpi: Open Source Epidemiologic Statistics for Public Health Version 3.01; URL:        [ Links ]

28. Escobar A, Mejia J, Villegas M, Portacio K. Prevalencia de la hipomineralización en pacientes escolarizados de la ciudad de Medellín. Repositorio Digital Universidad CES. 2015. URL:        [ Links ]

29. Jokovic A, Locker D, Tompson B, Guyatt G. Questionnaire for measuring oral health-related quality of life in eight- to ten-year-old children. Pediatr Dent 2004; 26:512-518.         [ Links ]

30. Téllez M, Martignon S, Lara J, Zuluaga J, et al. Correlación de un instrumento de Calidad de Vida relacionado con Salud Oral entre niños de 8 a 10 años y sus acudientes en Bogotá. CES Odont 2010; 23:9 -15.         [ Links ]

31. Microsoft Excel Corporation. Version 2016; URL        [ Links ]

32. Christiansen TB, Lauritsen JM. EpiData - Comprehensive Data Management and Basic Statistical Analysis System. Version 3.1; 2008, URL:        [ Links ]

33. StataCorp 2011. Stata Statistical Software United States; 2011.1 CD-ROM: color, 4 3/4 in.         [ Links ]

34. República de Colombia. Ministerio de Salud. Resolución N° 8430, 1993 URL:         [ Links ]

35. Vargas-Ferreira F, Ardenghi TM. Developmental enamel defects and their impact on child oral health-related quality of life. Braz Oral Res 2011;25:531-537.         [ Links ]

36. Arrow P. Dental enamel defects, caries experience and oral health-related quality of life: a cohort study. Aust Dent J 2017;62:165-172.         [ Links ]

37. Piovesan C, Antunes JL, Guedes RS, Ardenghi TM. Impact of socioeconomic and clinical factors on child oral health-related quality of life (COHRQoL). Qual Life Res 2010; 19:1359-1366.         [ Links ]

38. Clarkson J, O'Mullane D. A modified DDE Index for use in epidemiological studies of enamel defects. J Dent Res 1989; 68:445-450.         [ Links ]

39. Naranjo MC. Terminología, clasificación y medición de los defectos en el desarrollo del esmalte. Revisión de la literatura. Univ Odontol 2013; 32:33-44.         [ Links ]

40. Balmer R, Toumba J, Godson J, Duggal M. The prevalence of molar incisor hypomineralisation in Northern England and its relationship to socioeconomic status and water fluoridation. Int J Paediatr Dent 2012; 22:250-257.         [ Links ]

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons