Home About us Editorial board Ahead of print Current issue Search Archives Submit article Instructions Subscribe Contacts Login 


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2014  |  Volume : 12  |  Issue : 3  |  Page : 173-178

Prevalence of malocclusion among 15-year-old school children using dental aesthetic index in Nalgonda district, Andhra Pradesh, India: A cross-sectional study


1 Department of Public Health Dentistry, JSS Dental College and Hospital, JSS University, Mysore, Karnataka, India
2 Department of Orthodontics, JSS Dental College and Hospital, JSS University, Mysore, Karnataka, India
3 Department of Community Dentistry, Kamineni Institute of Dental Sciences, Narketpally, Nalgonda, Telangana, India
4 Department of Public Health Dentistry, Government Dental College and Hospital, Hyderabad, Andhra Pradesh, India
5 Department of Public Health Dentistry, Post Graduate Institute of Dental Sciences, PGIMS Campus, Pt. BD Sharma University of Health Sciences, Rohtak, Haryana, India

Date of Web Publication15-Nov-2014

Correspondence Address:
B R Chandra Shekar
Department of Public Health Dentistry, JSS Dental College and Hospital, JSS University, Mysore 570 015, Karnataka
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2319-5932.144788

Rights and Permissions
  Abstract 

Background: The available literature on the prevalence of malocclusion among school children in endemic fluoride areas in India is scanty. Objectives: The objective was to assess the prevalence of malocclusion using dental aesthetic index (DAI) and its association with gender, area of residence, and fluoride concentration among 15-year-old school children. Materials and Methods: This cross-sectional study was conducted among 15-year-old school children in the rural and urban areas of Nalgonda district, Andhra Pradesh, India. Two-stage cluster sampling was used for selecting the eligible children. Six out of 59 mandals in Nalgonda district were selected by simple random sampling technique. All the secondary schools in rural and urban areas of these mandals were listed and subsequently, four schools from each of these mandals were selected using random sampling. All eligible children aged 15 years were selected and assessed for malocclusion using Dentofacial anomalies with criteria of DAI by three trained and calibrated dentists. The DAI in relation to gender and area of residence were compared and analyzed using SPSS 16. Student's t-test and one-way ANOVA were used for comparing the mean values between groups. The qualitative data were analyzed using the Chi-square test. Results: A total of 1484 children was examined. The prevalence of malocclusion was 17.9%. The prevalence was significantly higher (P = 0.001) among females (23.6%) compared to males (13%). The prevalence was significantly higher (P = 0.001) in urban areas (22.2%) compared to rural areas (15%). The prevalence was significantly less (P = 0.001) in optimal (13%) and above optimal areas (8%) compared to below optimal areas (23%). Conclusion: The prevalence and severity of malocclusion were more among females, urban, and below optimal fluoride areas.

Keywords: Dental aesthetic index, endemic fluoride area, malocclusion, prevalence, rural and urban areas


How to cite this article:
Chandra Shekar B R, Suma S, Kumar S, Sukhabogi JR, Manjunath B C. Prevalence of malocclusion among 15-year-old school children using dental aesthetic index in Nalgonda district, Andhra Pradesh, India: A cross-sectional study. J Indian Assoc Public Health Dent 2014;12:173-8

How to cite this URL:
Chandra Shekar B R, Suma S, Kumar S, Sukhabogi JR, Manjunath B C. Prevalence of malocclusion among 15-year-old school children using dental aesthetic index in Nalgonda district, Andhra Pradesh, India: A cross-sectional study. J Indian Assoc Public Health Dent [serial online] 2014 [cited 2019 Jun 24];12:173-8. Available from: http://www.jiaphd.org/text.asp?2014/12/3/173/144788


  Introduction Top


India, a developing nation, faces many challenges in rendering oral health needs as majority of Indian population reside in rural areas, of which more than 40% are children <15 years. [1] It is necessary to know the prevalence and distribution of oral health problems and understand the dental health practices that people follow. This information is basic for formulation of oral health policies and appropriate programs, to improve awareness and knowledge of the general public about the preventive and promotive aspects of oral health, to create the required services, and to train the necessary dental manpower to meet these needs. [2] Lack of awareness about dental diseases has resulted in gross neglect of oral health. There is no component of oral health in the present health care system in India. The grass-root level health workers and doctors do not have adequate knowledge about prevention of oro-dental problems. All the above factors have resulted in poor oro-dental health of our population. [2] Among the dental diseases, malocclusion is the second most common in children and young adults, next to dental caries. [3]

One needs to establish certain criteria to rank patients properly according to the severity of the case and to distinguish between those whose malocclusion is severe enough to require orthodontic treatment and those with minor deviations. [4] Several indices have been used since the 1950s to assess the prevalence and severity of malocclusion. Among these are those by, Van Kirk and Pennell, [5] Draker, [6] Salzman, [7] Summers, [8] Bjork et al, [9] Massler and Frankel. [10] However, none of these methods has become universally accepted method for assessing malocclusion reliably. [11] More recently, index of orthodontic treatment priority, [12] peer assessment rating index [13] have been cited as the two most commonly used indices of occlusion. The authors claim that these indices could be used to assess the severity of malocclusion and its treatment needs. However, these indices also lack universal acceptance.

Many studies have been conducted in the past on dental caries and periodontal diseases with only a few studies on the prevalence and severity of malocclusion and orthodontic treatment needs in India. The studies carried out in Punjab, Delhi, Trivandrum, and Bangalore suggest that about 30% school going children suffer from some degree of malocclusion and half of them required comprehensive orthodontic treatment. [3] The results obtained from these studies have demonstrated wide variations in prevalence and distribution of malocclusion. One of the major factors responsible for this widespread variation was lack of consensus on the index to be used for assessing malocclusion. [14]

The use of fluorides in systemic as well as topical forms have substantially reduced dental caries prevalence in most of the developed countries and played a significant role in the control of the most common dental disease of mankind. [15] It is logical to assume that there might be a reduction in the prevalence of malocclusion due to pronounced reduction in the incidence of dental caries among school children. Dental decay is considered by some to exert a detrimental effect on occlusion; however, there is no complete agreement in the literature establishing the amount of dental malocclusion stemming from the early loss of tooth material. [16] Some studies have shown the lesser prevalence of some malocclusion traits in fluoridated areas than in nonfluoridated areas [17],[18],[19] while others found no such difference. [16]

Community water fluoridation which is not even being considered till now in India, in spite of its demonstrated benefits in the prevention of dental caries may be strongly recommended as the most cost effective dental preventive procedure for combating the two most common dental diseases among children, if the difference was to be evident. However, studies assessing the severity of malocclusion especially in endemic fluoride areas were scanty. With regard to the minimal data available on severity of malocclusion in this part of the world, as well as lack of consensus on the index to be used, the present study was undertaken to assess the malocclusion prevalence and its association with gender, area of residence, and fluoride concentration among 15-year-old school children using the criteria of dental aesthetic index (DAI).


  Materials and Methods Top


This cross-sectional study was conducted over a period of 3 months from March to May 2009. The ethical clearance for the study was obtained from the Institutional Ethics Committee. Two-stage cluster sampling was used to select the study participants. Nalogonda district has 59 mandals (administrative divisions within a district). Six of the 59 mandals in the district, were selected by simple random sampling technique as this provided approximately 10% of the mandals in the district. All the secondary schools in the rural and urban areas of these selected six mandals were listed out based on the official government notifications. The number of government higher secondary schools in rural areas were 3 times higher than the schools in urban areas in the selected mandals. This made us to select the schools from rural and urban areas in the ratio of 3:1. Then, four secondary schools (three rural schools and one urban school) from each of these six mandals were again selected at random. A list of all children from grades IX and X from the selected schools was obtained. The date of birth of the children was checked using the school records to ascertain the age.

All children aged 15 years who were available on the day of examination and who were continuous residents in those areas were considered for the study (census enumeration of all eligible children in selected schools). Participants with the previous history of orthodontic treatment or previous history of para-functional habits were not included in the final analysis. The permission for conducting clinical oral examination of these children was obtained from Headmasters of the concerned schools and district education officer. The parental consent for the study was obtained through a circular issued from the school authorities, and verbal consent was obtained from the eligible children.

The reliability of the questionnaire was assessed by determining the internal consistency between the first and second assessment during calibration. The questionnaire was satisfactory in yielding the desired information consistently (Cronbach's alpha 0.84). The training and calibration of the examiners were carried out using the trial forms (consisting questionnaire and DAI) on a group of 40 volunteers visiting the department. The intra-examiner reliability was considered to be satisfactory for DAI with a kappa co-efficient of 0.89.

Clinical oral examination was conducted by three trained and calibrated examiners under natural daylight on a foldable chair using mouth mirror and CPI probe. The instruments were sterilized using hot water sterilizer and chemical disinfectant (cidex-2.45% glutaraldehyde) in the absence of electricity. The demographic details, history of orthodontic treatment, any habits were collected using a predesigned close-ended questionnaire. The information was obtained using personal interview of the study subjects after completion of the oral examination by the same investigators to ensure uniformity in data collection. The data on malocclusion were assessed using DAI. [20] Three trained interns assisted for making the entries in the data collection sheet.

A volume of 500 ml of water sample from a common source was collected using a clean plastic bottle, coded and sent to the laboratory for estimation of fluoride concentration. The collection of water samples was done following the completion of the oral examination. Based on fluoride concentration in drinking water, the areas were divided into three categories viz., below optimal (<0.7 ppm), optimal (0.7-1.2 ppm), and above optimal (more than 1.2 ppm).

The data were entered onto a personal computer, and DAI score (DAI score) was computed using the regression formula described by WHO (Basic Oral Health Surveys 1997). [20] The subjects were assigned to one of the four categories suggesting a severity grade and a particular treatment need depending on the DAI score as described in [Table 1]. SPSS windows version 16 (IBM, Chicago, USA) was used for statistical analysis. The prevalence and severity of malocclusion between different categories were compared using Pearson's Chi-square test. The mean DAI score between different genders was compared using Student's t-test while the mean DAI score between different fluoride areas was compared using one-way ANOVA and Tukey's post-hoc test. The statistical significance was fixed at 0.05.
Table 1: Malocclusion and its severity according to DAI score


Click here to view



  Results Top


A total of 1484 children who fulfilled the inclusion criteria was considered for final analysis. The gender distribution of the study participants in relation to the area of residence and fluoride concentration in the drinking water is illustrated in [Table 2]. The prevalence of malocclusion (DAI score >25) was 17.9% among the study participants.
Table 2: Gender distribution of the study population in relation to the area of residence and fluoride concentration in drinking water


Click here to view


Association between malocclusion and gender

The prevalence of definite, severe, and very severe malocclusion among males was 10.1%, 3.8%, and 3.9%, respectively. The prevalence of definite, severe, and very severe malocclusion among females was 12.7%, 5.6%, and 5.3%, respectively. The prevalence and severity of malocclusion were higher among females compared to males [P = 0.001, [Table 3]. These results were true even while the comparison was made separately in rural [P = 0.018, [Table 3] and urban areas [P = 0. 001, [Table 3]. The mean DAI score was also significantly higher [P = 0.001, [Table 4] among females (22.64 ± 6.62) compared to males (20.89 ± 5.06). These results were true in both rural [P = 0.001, [Table 4] and urban areas [P = 0.001, [Table 4].
Table 3: Prevalence and severity of malocclusion in relation to gender and area of residence


Click here to view
Table 4: Mean DAI scores in relation to gender in rural and urban areas


Click here to view


Association between malocclusion and area of residence

The prevalence of definite, severe, and very severe malocclusion among study participants in rural areas was 8.1%, 3.1%, and 3.9%, respectively. The prevalence of definite, severe, and very severe malocclusion among study participants in urban areas was 13.3%, 5.0%, and 4.0%, respectively. The prevalence and severity of malocclusion were significantly higher in urban areas compared to rural areas [P = 0. 002, [Table 3]. The mean DAI among the participants in rural and urban areas was 21.38 (5.79) and 22.20 (6.03), respectively. The mean DAI was significantly higher among urban children compared to rural children [P = 0.008, [Table 4].

Association between malocclusion and fluoride concentration

The mean DAI score among the participants from below optimal, optimal, and above optimal areas was 23.49 (7.18), 20.92 (4.67), and 19.83 (5.90), respectively. The mean DAI score decreased with increasing concentration of fluoride in drinking water, and the finding was statistically significant even when the comparison was made between different fluoride concentrations among the rural and urban population separately [P = 0.0001, [Table 5]. The prevalence of definite, severe, and very severe malocclusion among participants residing in below optimal fluoride areas was 14.4%, 6.5%, and 7.1%, respectively. The prevalence of definite, severe, and very severe malocclusion among participants residing in optimal fluoride areas was 8.1%, 2.8%, and 2.1%, respectively. The prevalence of definite, severe, and very severe malocclusion among participants residing in above optimal fluoride areas was 5.8%, 0.9%, and 1.2%, respectively. The prevalence and severity were significantly higher in below optimal areas compared to other fluoride areas [P = 0.001, [Table 6].
Table 5: Mean DAI scores between different fluoride areas


Click here to view
Table 6: Prevalence and severity of malocclusion in different fluoride areas


Click here to view



  Discussion Top


A review conducted on the malocclusion studies in India found wide variation in the prevalence of malocclusion in different parts of the country. Lack of uniformity in data collection and variations in the indices used for assessing the severity of malocclusion were one among the many major factors for such widespread variations. [14]

In the present study, the prevalence of definite, severe, and very severe malocclusion was higher in urban than in rural areas. Dietary consistency determines the development of dentition and jaw musculature. Some animal studies have demonstrated that the consumption of soft and refined foods results in less biting force and less biting duration which in turn affects stimulation of the jaw bones and oral musculature leading to inadequate development of jaws and oral musculature along with improper eruption of teeth. [21],[22],[23],[24],[25] The consumption of softer and more refined food is part of the modern day lifestyle, seen predominantly in urban areas. The relatively primitive rural population will have less refined foods than the urban population. [26] The nature of the diet in man also plays a vital role in the evolution of the form and function of the dentition and the whole masticatory mechanism. [27] The consumption of soft and refined diet will fail to produce the attritional wear. This results in the lack of mesial migration of the teeth and ultimately a lack of space for accommodating all the teeth in the jaws which may predispose to crowding in the dental arches. [28] Besides this, the population in urban areas are more heterogeneous than in rural areas. [29] A higher prevalence of malocclusion in a heterogeneous population than in the primitive homogenous population was found in a study conducted by Lauc et al. [30] The higher prevalence of malocclusion in urban areas compared to rural areas was consistent with the findings of studies by Corruccini et al. [31] and Jalili et al. [32]

A higher mean DAI score was noticed among females than in males. The differences in the nutritional status, amount of food, and consistency of food consumed between males and females may again be the possible explanation for the higher prevalence of malocclusion among females. [32] This finding was consistent with results of studies conducted by Jalili et al. [32] in India and Helms in Denmark. [33] Traditionally, Indian females have poor nutritional status, less choice for selecting their food than males and also, they prefer food items which are softer and more refined than that consumed by males. [34] The prevalence of malocclusion among 15-year-old children in the National oral health survey and fluoride mapping [2] in India was 23.9% which was quite high compared to 17.9% found in our study.

The prevalence and severity of malocclusion decreased with increasing concentration of fluoride in the drinking water. The less premature loss of teeth in optimal and above optimal fluoride areas compared to below optimal fluoride areas may explain the difference in the prevalence and severity of malocclusion between different fluoride areas. [35] The results of studies by Krzoglu et al., [17] Plater [18] and Ast et al. [19] found the prevalence of some malocclusion traits to be significantly less, in optimum fluoride areas than low fluoride areas. However, these results need to be validated with further studies as we could not assess the fluoride consumption from other sources precisely.

Dento facial anomalies with criteria of DAI were used for assessing the severity of malocclusion for the simple reason that the use of this index which is included in the WHO oral health assessment form ensures uniformity in data collection. This could avoid widespread variations in the reporting of prevalence and severity of malocclusion assessed worldwide. Though, malocclusion is a multifactorial disease with heredity, hormonal differences, habits etc., playing a major role, these factors cannot be easily modified. Promotion of appropriate diet for a healthy life through well-planned health education will go a long way in the promotion of health and dental health of the population in a developing country like India. The benefits which accrue from public water fluoridation programs may be measured not only in terms of significant protection against dental caries but also with respect to a reduced hazard of malocclusion, especially severe malocclusion which may be regarded as physically handicapping.


  Conclusion Top


The combined prevalence of definite, severe, and very severe malocclusion among 15-year-old children was 17.9%. The prevalence was more among females and urban areas. Although, a statistically significant difference existed between different fluoride areas with regard to malocclusion status, the result may not be convincingly conclusive as malocclusion is multifactorial. Multiple logistic regression analysis considering all possible risk factors needed to be performed. The finding of less malocclusion with increasing fluoride concentration may be taken as a hypothetical conclusion of this study that needs to be validated with further studies having larger sample, the wider range of fluoride concentrations in drinking water and fluoride from other sources using multiple regression analysis.


  Acknowledgments Top


I would like to thank the Principal and Management of Kamineni Institute of Dental Sciences and Research Center for their continuous support and encouragement for undertaking this project. We thank the District Education Officer, Nalgonda, The headmasters of the schools concerned, and the participants for their kind co-operation. With deepest sense of admiration and gratitude, I express my thanks to Dr. M. Sirisha, Dr. Yasmeen Zubeda, Dr. Mohammadi Begum, Interns, Kamineni Institute of Dental Sciences for assisting in data collection.

 
  References Top

1.
Mahesh Kumar P, Joseph T, Varma RB, Jayanthi M. Oral health status of 5 years and 12 years school going children in Chennai city - An epidemiological study. J Indian Soc Pedod Prev Dent 2005;23:17-22.  Back to cited text no. 1
    
2.
Bali RK, Mathur VB, Talwar PP, Chanana HB. National Oral Health Survey and Fluoride Mapping 2002-03, India. New Delhi: Dental Council of India; 2004.  Back to cited text no. 2
    
3.
Parmesh H, Mathur VP. National oral health care program. Indian Pediatr 2002;39:1001-5.  Back to cited text no. 3
[PUBMED]    
4.
Saleh FK. Prevalence of malocclusion in a sample of Lebanese schoolchildren: An epidemiological study. East Mediterr Health J 1999;5:337-43.  Back to cited text no. 4
[PUBMED]    
5.
Van Kirk LK, Pennell EH. Assessment of malocclusion in population groups. Am J Orthod 1959;45:752-8.  Back to cited text no. 5
    
6.
Draker HL. Handicapping labio-lingual deviations: A proposed index for public health purposes. Am J Orthod 1960;46:295-305.  Back to cited text no. 6
    
7.
Salzmann JA. Malocclusion severity assessment. Am J Orthod 1967;53:109-19.  Back to cited text no. 7
[PUBMED]    
8.
Summers CJ. The occlusal index: A system for identifying and scoring occlusal disorders. Am J Orthod 1971;59:552-67.  Back to cited text no. 8
[PUBMED]    
9.
Bjoerk A, Krebs A, Solow B. A method for epidemiological registration of malocclusion. Acta Odontol Scand 1964;22:27-41.  Back to cited text no. 9
[PUBMED]    
10.
Massler M, Frankel JM. Prevalence of malocclusion in children aged 14 to 18 years. Am J Orthod 1951;37:751-68.  Back to cited text no. 10
[PUBMED]    
11.
McLain JB, Proffitt WR. Oral health status in the United States: Prevalence of malocclusion. J Dent Educ 1985;49:386-97.  Back to cited text no. 11
[PUBMED]    
12.
Brook PH, Shaw WC. The development of an index of orthodontic treatment priority. Eur J Orthod 1989;11:309-20.  Back to cited text no. 12
[PUBMED]    
13.
Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): Reliability and validity. Eur J Orthod 1992;14:125-39.  Back to cited text no. 13
    
14.
Kharbanda OP, Sidhu SS. Prevalence studies on malocclusion in India - Retrospect and Prospect. J Indian Orthod Soc 1993;24:115-8.  Back to cited text no. 14
    
15.
Fejerskov O, Ekstrand J, Burt BA. Water Fluoridation. Fluoride in Dentistry. 2 nd ed. Copenhagen, Denmark: Munksgaard; 1914. p. 275-87.  Back to cited text no. 15
    
16.
Hill IN, Blayney JR, Wolf W. The evanston dental caries study. XIX. Prevalence of malocclusion of children in a fluoridated and control area. J Dent Res 1959;38:782-94.  Back to cited text no. 16
    
17.
Krzoglu Z, Saglam AMS, Simsek S. Occlusal disharmonies of primary dentition in a high and a low fluoride area of Turkey. Fluoride 2005;38:57-64.  Back to cited text no. 17
    
18.
Plater WR. Caries control; its influence and effects on malocclusion. Am J Orthod 1949;35:790-6.  Back to cited text no. 18
    
19.
Ast DB, Allaway N, Draker HL. The prevalence of malocclusion, related to dental caries and lost first permanent molars, in a fluoridated city and a fluoride-deficient city. Am J Orthod 1962;48:106-13.  Back to cited text no. 19
    
20.
World Health Organization. Dentofacial Anomalies. Oral Health Surveys, Basic Methods. 4 th ed. Geneva, Delhi: A.I.T.B.S. Publishers and Distributors (Regd.); 1999. p. 26-9.  Back to cited text no. 20
    
21.
Corruccini RS, Beecher RM. Occlusal variation related to soft diet in a nonhuman primate. Science 1982;218:74-6.  Back to cited text no. 21
    
22.
Kiliaridis S, Engström C, Thilander B. The relationship between masticatory function and craniofacial morphology. I. A cephalometric longitudinal analysis in the growing rat fed a soft diet. Eur J Orthod 1985;7:273-83.  Back to cited text no. 22
    
23.
Kiliaridis S. The relationship between masticatory function and craniofacial morphology. III. The eruption pattern of the incisors in the growing rat fed a soft diet. Eur J Orthod 1986;8:71-9.  Back to cited text no. 23
    
24.
Burn-Murdoch RA. The effect of the consistency of the diet on eruption rates and lengths of incisor teeth in rats. Arch Oral Biol 1993;38:699-706.  Back to cited text no. 24
    
25.
Ciochon RL, Nisbett RA, Corruccini RS. Dietary consistency and craniofacial development related to masticatory function in minipigs. J Craniofac Genet Dev Biol 1997;17:96-102.  Back to cited text no. 25
    
26.
Mani UV. Rural vs. urban differences in diet and the prevalence of diabetes mellitus in western India. Int J Diabetes Dev Ctries 1998;18:7-9.  Back to cited text no. 26
    
27.
Emes Y, Aybar B, Yalcin S. The evolution of human jaws: A review. Bull Int Paleodont 2011;5:37-47.  Back to cited text no. 27
    
28.
Begg PR. Correct occlusion, the basis for orthodontics. Begg Orthodontic Theory and Practice. 3 rd ed. Philadelphia: W B Saunders;  1977. p. 7-50.  Back to cited text no. 28
    
29.
Rao MS. Introduction. Urban Sociology in India. New Delhi, India: Orient Longman Publisher; 1990. p. 335-8.  Back to cited text no. 29
    
30.
Lauc T, Rudan P, Rudan I, Campbell H. Effect of inbreeding and endogamy on occlusal traits in human isolates. J Orthod 2003;30:301-8.  Back to cited text no. 30
    
31.
Corruccini RS, Kaul SS, Chopra SR, Karosas J, Larsen MD, Morrow C. Epidemiological survey of occlusion in North India. Br J Orthod 1983;10:44-7.  Back to cited text no. 31
    
32.
Jalili VP, Sidhu SS, Kharbanda OP. Status of malocclusion on tribal children of Mandu (central India). J Indian Orthod Soc 1993;24:41-6.  Back to cited text no. 32
    
33.
Helm S. Prevalence of malocclusion in relation to development of the dentition. An epidemiological study of Danish school children. Acta Odontol Scand 1970;Suppl 58:1.  Back to cited text no. 33
    
34.
Barker M, Chorghade G, Crozier S, Leary S, Fall C. Gender differences in body mass index in rural India are determined by socio-economic factors and lifestyle. J Nutr 2006;136:3062-8.  Back to cited text no. 34
    
35.
Neidell M, Herzog K, Glied S. The association between community water fluoridation and adult tooth loss. Am J Public Health 2010;100:1980-5.  Back to cited text no. 35
    


    Figures

  [Table 6]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Materials and Me...
Results
Discussion
Conclusion
Acknowledgments
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed1490    
    Printed21    
    Emailed0    
    PDF Downloaded275    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]