|Year : 2011 | Volume
| Issue : 2 | Page : 128-134
Comparison of primary dentition caries experience in pre-term low birth-weight and full-term normal birth-weight children aged one to six years
Sowmya Anaberu Rajshekar1, Nagesh Laxminarayan2
1 Senior Lecturer, Department of Community Dentistry, Bapuji Dental College and Hospital, Davangere, Karnataka, India
2 Professor and Head, Department of Community Dentistry, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||9-Sep-2011|
Sowmya Anaberu Rajshekar
C/o Saroja Rajasekharappa, #507, 5th Main Road, PJ Extension - 577 002, Davangere, Karnataka
| Abstract|| |
Aim: The aims of the study were to determine and compare the primary dentition caries experience and the variables that may influence the occurrence of caries, in preterm low birth weight and full term normal birth weight children aged one to six years. Settings and Design: A cross-sectional comparative study was conducted among 250 full term normal birth weight (FTNBW) and 250 preterm low birth weight (PTLBW) children one to six years, born in the two hospitals in Davangere: Bapuji Hospital and Chigatere Hospital. A purposive sampling was used to select the study group. Materials and Methods: Required and relevant information regarding demographic characteristics, feeding practices and oral hygiene practices were obtained. Dentition status and treatment need index (World Health Organization 1997) was used to record dental caries. Statistical analysis used: Chi-square test, Student's t-test and ANalysis Of VAriance (ANOVA) test were used for statistical analysis. Results: Statistically significant difference was observed in caries prevalence between PTLBW and FTNBW groups (P<0.05), however, the difference in mean Decayed, missing and filled teeth index (dmft) was not statistically significant (P=0.30). Statistically significant differences were observed in caries experience between the two groups in relation to exclusive breast feeding for longer duration, i.e 7-12 months (P<0.05), bottle feeding habits (P<0.05) and sticky food consumption (P<0.01). Conclusions: A significant relationship was found between caries and PTLBW status though the difference in caries experience between the groups was not statistically significant, thus illustrating the higher caries risk in PTLBW children compared to FTNBW children.
Keywords: Dental caries, full term birth, low birth weight, preterm birth, primary dentition
|How to cite this article:|
Rajshekar SA, Laxminarayan N. Comparison of primary dentition caries experience in pre-term low birth-weight and full-term normal birth-weight children aged one to six years. J Indian Soc Pedod Prev Dent 2011;29:128-34
|How to cite this URL:|
Rajshekar SA, Laxminarayan N. Comparison of primary dentition caries experience in pre-term low birth-weight and full-term normal birth-weight children aged one to six years. J Indian Soc Pedod Prev Dent [serial online] 2011 [cited 2013 Dec 5];29:128-34. Available from: http://www.jisppd.com/text.asp?2011/29/2/128/84685
| Introduction|| |
Despite great achievements in oral health and even with dramatic advances in the armamentarium for fighting oral and dental diseases, such as dental caries and periodontal disease, these conditions remain prevalent in many parts of the world without regard for geopolitical boundaries. Dental caries, because of its ubiquitous nature and stubborn resistance to resolution, remains as one of the man's most common, oldest and single costliest ailment which poses a considerable challenge to the dental community. Despite its decline in all age groups on a worldwide basis over the past few years, especially due to fluoridation, its prevalence remains stable in primary dentition. It is still prevalent in developing countries and is a serious public health problem affecting children. In India, dental caries has been consistently increasing both in prevalence and severity over last five decades.
Dental caries is widely recognized as a multifactorial disease. Among the factors implicated in the causal model of caries are cariogenic bacteria, fermentable carbohydrates, susceptible tooth and time. The factors which cause dental caries in young children are many: Repeated exposure to cariogenic substances, the duration of a feeding habit, micro-organisms, the structure and the defence mechanism of the body and the tooth. Other associated risk factors include poor economic conditions, enamel hypoplasia, malnutrition and chronic diseases and low birth weight including preterm births. 
A preterm birth, as defined by the World Health Organization (WHO), is birth of an infant prior to 37 weeks gestation.  Low birth weight is defined as the newborn weighing less than 2,500 grams at birth.  Prematurity and low birthweight can be the cause of long-term illness and disability, including developmental delays, chronic respiratory problems, vision and hearing impairment. Pre-term low birth weight (PTLBW) is also implicated as a contributor to impaired immune function which may be sustained throughout childhood as long as five years in some children.  Studies by Seow , and co-workers have shown that even the dentition developing during the time of birth may be affected. Low birth weight, including preterm births, predisposes to high levels of streptococcal colonization due to reduced immunofunction, in addition to favouring the development of enamel hypoplasia and salivary disorders. ,,,,
The relationship between preterm low birth weight and dental conditions has not received much attention and most of what has been done looks at enamel defects. Studies of the association between PTLBW and caries have been hampered by small sample sizes with resulting low statistical power. Previous studies have described a higher caries prevalence and experience in primary dentition of children born preterm low birth weight. ,,, A study by Fadavi and coworkers  showed a strong correlation between different birth weight groups and prevalence of caries. They concluded that children with very low birth weight (VLBW <1500 g) have a greater risk of dental caries than those with low birth weight (LBW <2500 g). The prevalence rates vary considerably due to differences in methods, age at examination, diagnostic criteria. Recently, a systematic review by Burt and Pai  which included four scientific studies reported that there is no relationship between low birthweight and the development of dental caries. However, they concluded that the results are based on very limited evidence and therefore cannot reject the possibility that there is a link between PTLBW and subsequent development of caries.
Scarcity in studies exploring the association between PTLBW status and dental caries has made it obscure to understand the exact role. Studies are not conducted over a long enough period of time, do not have adequate numbers and do not collect sufficient information on likely variables affecting the outcome. Hence, an attempt is made in this study to assess and compare the caries experience and the variables that may influence the occurrence of caries in the primary dentition of preterm low birth weight and full term normal birth weight children aged one to six years. The study hypothesis is that there is a difference in the primary dentition caries experience between preterm low birth weight and full term normal birth weight children. The null hypothesis is that there is no difference in the primary dentition caries experience between preterm low birth weight and full term normal birth weight children.
| Materials and Methods|| |
The proposed study was reviewed by the ethical committee of Bapuji Dental College and Hospital, Davangere and clearance was obtained. Before conducting the study, permission was obtained from the concerned authorities of Bapuji Hospital and Chigatere Hospital, Davangere to list out the children from the birth records. Voluntary written informed consent was obtained from the parents of the children participating in the study before examination and investigation. A specially prepared and pretested proforma was used for recording the data. A questionnaire interview was conducted for the parents of all the participants by the examiner herself prior to the start of clinical examination. The required information was collected by the mother/guardian of the child by translating the questions into the local language. The details of each child about birth date, birth weight and relevant medical history were obtained from the hospital records and the personal patient records were maintained. Social class stratification was done based on Kumar's modification of BG Prasad's classification for social class classification (categorized into social class 1, 2, 3, 4 and 5 based on the total family income).
The sampling methodology adopted was purposive sampling. Children who were born preterm low birth weight and full term normal birth weight at the two hospitals in Davangere, namely Bapuji Hospital (Private) and Chigatere Hospital (Government) during the period of 2000 January to 2005 January were listed from the birth records and traced out for the study. Only those children whose residential address was in Davangere were selected for the study. While tracing out, those with missed out address and not willing to participate in the study were excluded. Children who were medically compromised, handicapped and those with congenital defects were excluded from the sample.
A pilot study was carried out earlier for selection of sample to check the feasibility and relevance of proforma. Pilot study assessments were utilized for proper planning and execution of main study. The data obtained out of pilot study was used for arriving at final sample size by using statistical methods.
Criteria for considering birth status and birth weight
- Preterm low birth weight - Children born before 37 complete weeks of pregnancy with a birth weight of less than 2,500 grams (up to and including 2,499 g) were included under the study.
- Low birthweight (LBW) - weight at birth of <2,500 g (up to and including 2,499 g).
- Very low birthweight (VLBW) - weight at birth of <1,500 g (up to and including 1,499 g).
- Preterm (PT) if they are born in the gestational week 33-36.
- Very preterm (VPT) infants - Children born in the gestational week 29-32.
- Full term normal birth weight (FTNBW) - Children who were born between 37-42 weeks of gestation with a birth weight of ≥2,500 g - 3999 g were included under the study.
Full term low birth weight children were excluded from the study.
Details of clinical examination
Clinical examination of the study subjects was carried out by investigator herself. The investigator was calibrated in order to limit the examiner variability and the results were subjected to Kappa Statistics. A recording assistant was trained to assist the recording procedure.
Examination was carried out by making the child sit on an ordinary chair with back rest, with the examiner standing behind the chair. For young children, examination was carried out by making the child sit on his/ her mother's lap with the examiner sitting in front of the child. Artificial illumination was used at times when required, using torch light. Dental caries was recorded using WHO criteria (1997). 
The data obtained was compiled systematically and subjected to statistical analysis (Statistical Package for the Social Sciences - SPSS Version 12, USA, and Cystat software). Chi-square test was used for data comparison between groups and within groups, and estimation of statistical significance. A probability level of 0.05 was set to be highly statistically significant. Student's t-test was used to test the difference between the two means of independent observations made on individuals of two different groups drawn from two populations. ANalysis Of Variance (ANOVA) test was used to compare more than two sample means drawn from corresponding populations.
| Results|| |
The study population comprised of 500 children aged one to six years among which 250 were FTNBW (137 boys, 113 girls) and 250 PTLBW (138 boys, 112 girls) [Table 1] and [Table 2]. The Kappa co-efficient values for intra-examiner and inter-examiner reliability were 0.9 and 0.9 respectively.
|Table 2: Distribution of study population according to gestational age and birth weight|
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Feeding and dietary behaviors
303 children (60.6%) had been exclusively breast fed for one to six months and 177 (35.4%) for seven to twelve months months, while 20 (4%) had never been breast fed [Table 3]. Among the study population, only 89 (17.8%) children had been bottle fed and 71 (14.2%) had the history of night bottle habits [Table 4]. More number of children had been bottle fed in PTLBW group (53, 21.2%) compared to FTNBW group (36, 14.4%). Overall, 301 (60.2%) children had the history of consumption of sticky foods with a frequency of once per day (200, 40%) and more than once per day (101, 20.2%) [Table 5].
|Table 3: Comparison of caries prevalence and caries experience among study population based on the duration of exclusive breast feeding|
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|Table 4. Comparison of caries prevalence and caries experience among study population based on the history of bottle feeding|
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|Table 5: Comparison of caries prevalence and caries experience among study population based on the frequency of sticky food consumption|
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Oral hygiene practices
Majority of the children (369, 73.8%) used toothbrush and toothpaste to clean their teeth. 79 (15.8%) had no habit of cleaning their teeth. 333 (66.6%) children cleaned their teeth once daily and 88 (17.6%) twice daily.
Dental caries data
Out of 500 children, 217 (43.4%) had caries. Among them, 97 (38.8%) were from FTNBW group and 120 (48%) were from PTLBW group. This difference was statistically significant (χ2 =4.31, P <0.05, S). The mean Decayed, missing and filled teeth index (dmft) was slightly higher in PTLBW group (1.3 ± 1.8) compared to FTNBW group (1.1 ± 2.2) (t=-1.03, P=0.30, NS). The mean decayed teeth (dt), missing teeth (mt) and filled teeth (ft) values were high among PTLBW children i.e 1.1 ± 1.6, 0.1 ± 0.3 and 0.1 ± 0.6 compared to FTNBW children, i.e 1.0 ± 2.1, 0.02 ± 0.1 and 0.06 ± 0.3, respectively.
The prevalence of caries in children weighing ≥2500 g was 38.8%, 1500g-2500 g was 46.2% and ≤1500 g was 57.9% (P<0.05). There was an inverse relation between the prevalence of caries and birth weight. The mean dmft in NBW, LBW and VLBW groups was 1.1 ± 2.2, 1.2 ± 1.7 and 1.6 ± 2.4, respectively. The mean dmft increased with decreasing birth weight. Lower the gestational age, higher the prevalence and mean dmft. (29-32 weeks, 55.4%, 1.29 ± 1.6; ≥37 weeks, 38.8%, 1.1 ± 2.2; P=0.59).
Relationship of caries rates to demographic characteristics
The prevalence of caries and the mean dmft in both the groups increased with increasing age. Among the girls, the prevalence of caries and the mean dmft was high in PTLBW group (51, 45.5%, 1.3 ± 1.9) compared to FTNBW group (35, 31%, 0.7 ± 1.4) and the difference in mean dmft between the groups was statistically significant (P<0.01). The prevalence of caries was highest among children in social class V in both the groups i.e 44.7% (n=21) in FTNBW and 55.9% (n=62) in PTLBW.
[Social class stratification was done based on Kumar's modification of BG Prasad's classification for social class classification (categorized into social class 1, 2, 3, 4 and 5 based on the total family income). Details added in [Table 1]
Relationship of caries rates to feeding and dietary behaviors
The prevalence of caries and the mean dmft in both the groups was highest among children who had never been breast fed, with night bottle habits and the habit of sticky food consumption. As the frequency of bottle feeding increased, caries prevalence and the mean dmft increased. Among children who had been breast fed for 7-12 months, the difference in mean dmft between the groups was statistically significant (P<0.05) [Table 3]. There was also a significant difference between the groups in relation to mean dmft and bottle feeding habit (P<0.05) [Table 4]. Children who consumed sticky foods once per day showed a higher caries prevalence, and the mean dmft in PTLBW group compared to FTNBW group and the difference in mean dmft was statistically significant (P<0.01) [Table 5].
Relationship of caries rates to oral hygiene practices
The difference in mean dmft between the groups was not statistically significant based on of the type of oral hygiene aid used.
| Discussion|| |
In the present study, prevalence of caries was significantly associated with prematurity of birth and low birth weight (P<0.05). It was found that PTLBW children had a slightly higher caries experience than FTNBW children. Similar results were obtained in other studies. ,, In contrast, it is interesting to note high dmft values for FTNBW children compared to PTLBW children in few studies , though the differences were not significant. Thus, a clear picture is not available because of limited evidence and small sample size.
The mean dmft was high in PTLBW children, however, the difference was very less . This can be attributed to the following reasons: When dealing with young children below 3 years, to ensure their compliance with the examination, carious lesions were diagnosed solely on a visual examination; this might have resulted in an underscoring of the actual caries lesion status. While epidemiological evidence indicates that non-cavitated carious lesions are more prevalent than cavitations during the first 18 months of life,  the WHO criteria for caries depend solely on cavitated lesions, thus underestimating the scores in these children. There were more children of younger age group in the present study, and the exposure of teeth to oral environment is for relatively shorter period of time. Since time is one of the important factors under etiology and increasing age has the potential to increase caries risk, most of the teeth were not likely to become carious at the study period.  In addition, VLBW children have a higher caries risk compared to LBW and NBW children.  In the present study, since majority of the children belonged to LBW category and as there were only few VLBW children, this might have contributed to the lower caries experience.
There was statistically significant difference (P<0.05) in the prevalence of dental caries between PTLBW children (48%) and FTNBW children (38.8%). Similar finding was observed in a study which showed a significant association between caries and prematurity of birth.  The present results are higher compared to few studies  and lower compared to a study done by Li et al., thus demonstrating varied prevalence rate among PTLBW children in the same age group range. The higher prevalence was due to the high risk to develop dental caries in these children. A lack of breast feeding or exclusive breast feeding for shorter duration in these children leads to undernourishment during maturation phase of teeth. Breast milk is well recognized as the best diet for infants which provides many specific nutrients that inhibits the growth of several microorganisms, including mutans streptococci.  In addition to this, due to maternal lactation failure, these children turned to alternatives such as bottle feeding, milk based substitutes and solid foods very early in their life, which might have contributed to the above findings in the present study. This is consistent with some previous studies. , The greater systemic derangement associated with VPT and VLBW children is said to result in systemic insults to the developing primary teeth which can lead to disturbances in the mineralization resulting in hypoplasia, and thus predisposing the teeth to caries. , It was also observed that lower the social class, higher the caries occurrence. This can be attributed to the low family income and the degree of education in the lower social classes which can affect food selection, nutrient intake, health values, life style, oral hygiene practices, access to health care information and susceptibility to childhood infections. ,, Added to this is the PTLBW status, which is so often a marker for deprived social circumstances that it carries all the caries' risks that come with it. All these factors together will create an atmosphere which is favourable for the cariogenic organisms to develop and multiply, resulting in higher caries occurrence in these children.
Totally valid comparisons could not be done between the present study and with those previously reported in the literature due to wide variations observed in the methodology, different study settings, selected age groups and the indices used. This study had a limitation in the execution. A systematic sampling method could not be employed for selection of children as it was not feasible due to certain practical difficulties. In the present study, the body mass index of the children at the time of birth or during the examination was not available and the presence of enamel hypoplasia was not detected; it is unclear whether dental caries was preceded by enamel hypoplasia or undernourishment, or both. In addition, the streptococcus mutans levels and the oral hygiene status of individuals which can influence the results were not measured.
In conclusion, the present study found that PTLBW children had a slightly higher caries experience than FTNBW children, however, the difference was not statistically significant. PTLBW children are more likely to experience dental caries if they are breast fed for longer duration, had bottle feeding habits and the habit of sticky food consumption. However, lack of statistical significance does not imply that there is no relationship between the two because statistical significance has its own limitations. It should be remembered that a statistical conclusion about significance does not always agree with clinical significance in the medical field; one which is statistically not significant, may not be clinically insignificant.
The results of the present study indicate that prematurity of birth and low birth weight increase the risk to develop caries in the primary dentition, thus highlighting the risk groups that should be targeted by the medical, dental and para-medical professionals, and the need to implement preventive measures is also higher in this group. It provides a basis for further longitudinal studies to explore and clarify the relationship between PTLBW status and occurrence of dental caries in the primary dentition. The relationship of other cariogenic factors must be determined before appropriate prevention programs are established.
| Acknowledgement|| |
Dr D.K.Sangam, biostatistician, Professor, Jagadguru Jayadeva Murugarajendra Medical College and hospital, Davangere, for statistical analysis.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]