INTRODUCTION:

If one or more decayed, missing or filled tooth surface is present in any primary dentition of children under the age of 71 months is defined as early childhood caries (ECC)^[1]. 60-90% of school-aged children are affected by dental caries and it is quite a big public health issue^[2]. Children from lower social and economic backgrounds tend to have an increased prevalence of caries^[3]. Intermingling between the ingested carbohydrates and cariogenic bacteria in the mouth can produce acids that cause demineralization of the teeth enamel, which is the root cause for dental caries^[3].

Our quality of life and our ability to function is affected by the pain and infection caused by dental caries, which are extremely distressing and can have a negative impact on us and on our day to day activities^[4]. This can lead to lost productivity and also involve high health care costs^[5] such as general anesthesia for treatment which is needed for severe cases. The early loss of primary dentition can lead to dental problems in the permanent dentition.

In 1927, reports were performed regarding dental caries in babies and it was one of the first to be published^[6]. Although no research regarding this matter existed at this period, many studies since then have showed results with respect to feeding habits and dental caries^[7,8], which are unclear.

Decrease in infectious diseases, morbidity and low weight in newborns are some of the benefits seen in breastfeeding^[9]. It also decreases the risk of infections in the gastrointestinal tract and skin inflammations, as highlighted by the PROBIT trial^[10]. Breastfeeding in children has been suggested by the World Health Organization (WHO) at least till six months of age, and breastfeeding along with food intake is suggested until the age of two years, although the practice does not help in the growth and development of normal occlusion. ^[11,12]. But, society and culture directly play a role in affecting the knowledge of how long a child should be breastfed for, as it differs from one another^[13]. The proof to state that infant feeding as a risk factor for early childhood caries is inconsistent. The carbohydrate content of the milk that is breast milk or bottle milk, and certain factors such as the contact time between breast milk or bottle milk and the primary dentition. That is the frequency of feeding, certain positions that can cause accumulation of milk on the teeth surface while putting babies to sleep are the causes for the risk of dental caries.

The age at which colonization takes place and the levels of cariogenic bacteria such as Streptococcus mutans present in an infant’s mouth, are the main factors that determine caries risk^[14]. There is an increased caries risk if the colonization by these type of bacteria occurs at a young age^[15]. Breast milk contains certain breast-specific Lactobacilli bacteria and substances including human casein and secretory IgA, which are not present in formulated bottle milk. These substances inhibit the growth of cariogenic bacteria and prevent them from sticking onto the teeth surface, oral Streptococci specifically^[16,17]. The risk of early childhood caries is also influenced by the presence of teeth and increases when the number of teeth increases. The risk tends to change when the infant starts to include foods and drinks other than breast milk or bottle milk to their diet. This can vary depending on the content of carbohydrate, acid levels and frequency of the new diet.

The concern here is that whether bottle feeding is more cariogenic than breastfeeding remains unclear even today. While some studies have showed that such a link exists^[18] some authors have not found a connection between breastfeeding and dental caries^[19-21]. Bottle feeding has been stated as a risk factor for dental caries by some authors^[22-24], while no such link was found by another author^[24]. Due to contradictions between these findings, further studies are necessary to resolve the existence of this association^[25]. A systematic review of literature analyzing the relationship between breast feeding and dental caries was published in the year 2000. In this 24 case-control studies, 3 case series studies and 1 cohort study was included. The systematic review was unable to state that breastfeeding was a risk factor of dental caries. However, comparisons between breast feeding and bottle feeding was not reported in the review conducted by Hesch R and his team^[26]. Moreover, the systematic review on risk factors for dental caries in young children^[27] identified the following factors as risk factors for early childhood caries, which are related to breast feeding and bottle feeding: when the duration of feeding was more than 18 months, used to feed to stop crying during the night, and to put the child to sleep.

There is no confirmation as to whether bottle fed children are more prone to dental caries in primary dentition than breastfed children, as none of these reviews compared these two types of feeding methods in relation to dental caries. Until today, the question of whether bottle feeding can contribute to an increased risk of dental caries compared to breastfeeding remains uncertain, as none of the reviews targeted to answer this.

More understanding of the subject is needed and improved knowledge can help dentists provide more appropriate instructions which will lead to healthier children. The prevalence of dental caries in childhood is a vital matter, which should be thoroughly discussed and treated as it plays an important role in the well-being, growth^[28] and quality of life^[29].

Diagnosis of dental caries:

Most studies used WHO criteria ^{[20,21,30,31]} for diagnosis of dental caries, while one study used three different criteria (those were ICDAS, WHO and Nyvad)^[23]. One author^[30] classified the presence of caries presence into three types: type 1 being caries, type 2 being rampant caries and the third being incisor caries. The group “with caries” was defined according to WHO criteria, two or more upper deciduous incisors with carious labial or palatal surfaces were defined as rampant caries, while this tooth group considered only incisor caries.

Feeding patterns and habits:

There was a difference in the criteria that was used to define types of feeding habits, which differed between studies, but the data concerning the presence and absence of bottle feeding and breastfeeding was considered by all studies. Breast feeding or bottle feeding at birth^[31] was considered by one author; two researchers considered feeding habits up to 6 months or more than that^[20,22] was considered by two authors, one author considered exclusive breastfeeding up to 12 months^[19], and others considered feeding habits during infancy^[21,23,30]. Study^[48] showed that children who were bottle fed for more than 12 months had a higher prevalence of caries than those who were bottle fed for less than 3 months. This study also stated that nocturnally bottle fed children had a higher percentage of ECC compared to those who were not bottle fed at night (P<0.001). A Brazilian study also states that frequent breastfeeding might increase the risk of dental caries ^[8] despite its health benefits.

Breastfed versus bottle fed:

No significant difference in the prevalence of caries between the two groups^{[32,33,34–36,37]} was reported in these cross-sectional studies; A cohort study and one cross-sectional study reported significantly lower caries in breastfed children^[38,39]; one cross-sectional study found a lower adjusted caries risk in children who were breast fed versus children who were bottle fed (OR = 0.61, 95%CI 0.39–0.97, p = 0.038)^[40]; one cohort study reported higher increase in caries in children who were breast fed between one to one and a half years, but the association disappeared in the multivariate analysis; one cross-sectional study reported that ever breast fed children had an increased risk of caries of borderline significance (p = 0.08)^[41]; and one cross-sectional study found a lower adjusted caries risk in breastfed versus bottle fed children. A study conducted in southwestern Nigeria^[48] stated that children who were solely bottle fed had a 33% caries prevalence whereas children who were both breast and bottle fed had 25.3% and those who were solely breastfed had the least prevalence of 15.7%. A study conducted in Sri Lanka^[20] stated that adding sugar to formula milk increased the risk of dental caries, but this was not statistically significant.

DISCUSSION:

The diverseness of the study designs in this review was analyzed. Due to the heterogeneousness of studies and variation in feeding habits and dental caries classification, the course was made complex^[42]. WHO criteria^{[19,20,23,30,31]} was used by most studies to diagnose dental caries. The practice of feeding was classified particularly into breast feeding, bottle feeding and mixed feeding by the authors of this study. Content of bottle milk was not analyzed in any of the articles. Sugar content in bottle milk, culture, dental visits for early prevention, fluoridation in water and on-demand feeding at night are some of the factors that can be included. Two factors, sugar content in the milk bottle and on-demand feeding at night can also can lead to an increase in the risk of dental caries, while factors such as water fluoridation, dental visits for early prevention can be protective factors. It is better to consider the above mentioned factors during the collection of data. It is difficult to assess the role of feeding habits in the etiology of dental caries due to presence of reasonable confounding as the establishment of the causal link between a risk factor and outcome is an upstream^[43]. Absence of blindness while determining the relationship between breast/bottle feeding and dental caries is one general reason for the reduction in quality of the article. When the clinical examination for the diagnosis of dental caries was done, researchers from study^[31] were not aware of the mother’s response regarding feeding practices. Data and information regarding feeding habits was collected through interviewing care takers or mothers. This type of data may be biased as they could not remember or they were unable to provide precise information. One of the study evaluated feeding habits through personal interviews or questionnaire, while dietary data was used for the collection of data in the remaining study as an attempt to reduce memory bias.

Precise information regarding feeding habits was not given by the care takers or mothers. This can lead to biased information. Mothers may tend to overestimate the duration of breastfeeding, based on their knowledge in it. For instance, information from the variable “breastfeeding” vs. “bottle feeding” was used. Another study used the variable “breastfeeding for up to 6 months”^[20]. This categorical variable was used in two studies^[30,31], but they failed to report time data. Irrespective of the time duration of breast feeding mothers and caretakers were able to say “yes” for breast feeding. This could vary from month to month for each mother.

Three cross-sectional^[23,30,31] studies and The cohort^[22] study and two cross-sectional^[23,31] showed that children who were breastfed had significantly less frequency for being affected by dental caries than bottle fed children. Analysis revealed that breastfeeding also had a protective function against dental caries in comparison to bottle feeding. Most of the studies suggest the goodness of breast feeding for dental caries except two cross-sectional^[20,21] and one case-control study^[19], as they did not find statistical significance between these associations. Fewer dental caries was seen in children who were breastfed for more than 12 months in comparison to those who were breast fed for a shorter time period. Moreover, there is a finding that states that there is an increased risk of dental caries in children ^[44] who were breastfed at night for more than 12 months and thus this should not be encouraged.

Current scientific literature and evidence suggests for breastfeeding to have a greater protective effect against early childhood caries than bottle feeding. It is recommended to breastfeed children for a minimum of at least 6 months^[12] as it benefits the systemic health of these children ^[10,45].

CONCLUSION:

The current scientific literature which is available showed that breastfeeding is much more effective when it comes to preventing dental caries in children than bottle feeding. But some articles stated that the time duration and frequency of breastfeeding increased the risk of dental caries. However, breastfeeding should be encouraged as the exclusive method of feeding for a minimum 6 months while being cautious about the frequency and nocturnal feeding. Complementary breastfeeding for up to about two years should be encouraged for all children. This should be in accordance with the recommendations of WHO/ UNICEF.

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Received on 27.05.2016 Modified on 30.05.2016

Research J. Pharm. and Tech 2016; 9(9):1508-1512.

DOI: 10.5958/0974-360X.2016.00294.8