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Year : 2020  |  Volume : 31  |  Issue : 1  |  Page : 129-133
Erosive effect of milk, honey, cereal porridge, and millet porridge on enamel of primary teeth: An in vitro study

1 Department of Pedodontics and Preventive Dentistry, The Oxford Dental College, Bengaluru, Karnataka, India
2 Department of Preventive Dental Sciences, Division of Pedodontics, College of Dentistry, Jazan University, Jizan, Kingdom of Saudi Arabia

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Date of Submission13-Mar-2018
Date of Decision27-Mar-2018
Date of Acceptance08-Aug-2018
Date of Web Publication02-Apr-2020


Context: Enamel erosion is manifested as partial demineralization occurring at the enamel surface leading to increased surface roughness. Diets comprising milk, cereals, and millets are frequently fed to infants and toddlers. These foods are prepared so as to make them soft in texture, palatable, and easy to ingest. Aim: To determine the erosive effect of milk, honey, and porridges made from cereal and millet on primary tooth enamel. Settings and Design: Exfoliated caries-free primary teeth were collected, and a total of 50 longitudinal sections were prepared. They were equally divided into five groups of 10 samples each. Materials and Methods: Each group was incubated in milk, honey, cereal porridge, millet porridge, or saliva for 30 min. Subsequently the samples were washed and incubated at 37°C in saliva for 2 h. This cycle was repeated five times. The samples were gold sputter coated, and surface roughness was measured using optical profilometry. Saliva samples were evaluated for calcium release using dry chemistry method. The pH of foods and titratable acidity were also estimated. Statistical Analysis Used: One way analysis of variance and Tukey's post hoc test. Results: The mean surface roughness value, Ra (μm), obtained with millet porridge was 6.0175 ± 0.54 μm, which was significantly higher than cereal porridge, honey, and milk (P < 0.05). Calcium release in saliva was highest with honey (>14 mg/dL) and it also exhibited the lowest pH (4.33). Conclusion: Porridges prepared from millet and brown rice cereals were seen to have an erosive effect on the enamel of primary teeth.

Keywords: Enamel, erosion, pH, primary teeth, surface roughness, weaning

How to cite this article:
Cherian TS, Subramaniam P, Gupta M. Erosive effect of milk, honey, cereal porridge, and millet porridge on enamel of primary teeth: An in vitro study. Indian J Dent Res 2020;31:129-33

How to cite this URL:
Cherian TS, Subramaniam P, Gupta M. Erosive effect of milk, honey, cereal porridge, and millet porridge on enamel of primary teeth: An in vitro study. Indian J Dent Res [serial online] 2020 [cited 2022 Jan 20];31:129-33. Available from:

   Introduction Top

Dental erosion can be defined as the loss of dental tissue as a result of a chemical event containing no bacteria.[1] It is the chronic loss of tooth substance in the presence of acids, without the involvement of bacteria characterized clinically as corrosive–abrasive wear.[2] Acid exposure causes enamel surface demineralization, and long-term demineralization leads to erosive enamel wear as a consequence of progressive mineral loss. A decrease in the pH of the oral cavity below the critical pH of enamel, which is reported to be 5.5, results in the occurrence of enamel erosion.[3] Diet is the most important cause for dental erosion.[4] The erosive potential of foods depends on their pH, acid concentration, length of exposure, titratable acidity, mineral content, clearance on tooth surface, and its calcium chelating properties.[5] Erosion is also influenced by the behavioral characteristics of a patient (eating and drinking habits, lifestyle, excessive acid consumption) and the biological structure of the teeth and saliva (salivary flow rate, buffering capacity of the saliva), pellicle formation, and anatomy of the dental hard tissue and soft tissue.[6]

Dental erosion involves histological changes in the dental hard tissue. In the early stages, the mechanical and physical properties of the tooth are altered, as minerals are released due to erosive acid. Enamel and dentine are affected differently.[4] Due to the very high mineral content of enamel, erosion of enamel is initially manifested as a partial demineralization of the surface leading to softening and increased surface roughness.[7]

Various studies[8],[9],[10] have reported the erosive effect of frequent consumption of fruit juices, energy drinks, and carbonated soft drinks on the surface enamel of teeth in children. However, there are very few studies that have assessed the erosive potential of weaning foods given to infants and toddlers. There is a possibility that regularly consumed foods, such as milk and porridge, prepared from cereals and millets given to infants could have an erosive effect on teeth. Hence, the aim of this study was to determine the erosive effect of milk, honey, and porridges made from cereal and millet on the primary tooth enamel.

   Materials and Methods Top

Exfoliated caries-free primary teeth that were stored in normal saline were used in this study. Teeth with discoloration, dental caries, restorations, and traumatized or cracked teeth were not included in the study. The selected primary teeth were cleaned using a rubber cup and water and then sectioned in a buccolingual direction using a diamond disc, to give a total of 50 longitudinal tooth sections. The dentinal surface of each sample was coated with an acid-resistant nail varnish and was then stored in 0.9% sodium chloride solution.

Test foods selected for the study were milk, honey, brown rice (cereal; botanical name: Oryza sativa), porridge, and ragi (millet; botanical name: Eleusine coracana) porridge. The brown rice porridge was prepared using water and salt. The ragi porridge was prepared using milk and jaggery. Saliva was used as the control. The pH of these foods was estimated using a digital pH meter and titratable acidity was assessed. As the test food samples were either viscous or semi-solid, they were diluted with neutral demineralized water (pH 7.05) in the ratio of 10 cc of food: 90 cc of water.

The enamel samples were randomly divided into five groups, consisting of 10 samples each and immersed in 20 mL of the test foods as follows – Group 1: 20 mL of saliva (control), Group 2: pasteurized bovine milk, Group 3: honey, Group 4: brown rice porridge (cereal), and Group 5: ragi porridge (millet). The enamel samples were incubated at 37°C in a humidified atmosphere of 5% carbon dioxide and 95% air in a gas incubator for 30 min.[11] Following incubation, the samples were washed with phosphate buffer and vortexed for 30 seconds to remove any remnants of the test food. They were then transferred into sterile Eppendorf tubes containing saliva (pH = 6.5) to simulate the oral environment and incubated for 2 h at 37°C in a humidified atmosphere of 5% carbon dioxide and 95% air in a gas incubator. This entire procedure was repeated five times. The enamel samples were dried and were gold sputter coated because white surface of the teeth cannot be detected by the profilometry system. Surface roughness of enamel was assessed in triplicate using optical profilometry,[12],[13],[14] and surface roughness was measured as roughness average (Ra) value expressed in micrometer (μm) using Wyko NT1100 Optical Profiling System (VEECO)[15],[16] [Figure 1]. The saliva from each of the Eppendorf tubes in which the tooth samples were placed for 2 h was collected and analyzed for calcium content using dry chemistry method using Vitros 5600.[17]
Figure 1: The surface roughness analysis result of a sample using Wyko NT1100 Optical Profiling System (VEECO)

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Data were subjected to statistical analysis using one-way analysis of variance and SPSS software version 22. Tukey's post hoc test was carried out to assess significant differences if any between the test foods.

   Results Top

[Table 1] shows mean pH and titratable acidity of saliva (control) and the test foods. Honey showed the lowest pH (4.33). Ragi porridge and honey showed higher values of titratable acidity.
Table 1: pH and titratable acidity of saliva and test foods

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The mean surface roughness of enamel following immersion in test foods was high in ragi porridge [Table 2]. On comparison of the test foods with that of saliva, the enamel samples immersed in both porridge preparations and honey showed significantly higher surface roughness of enamel (P ≤ 0.05) [Table 3]. There was also a significant difference between enamel surface roughness values obtained following immersion in ragi porridge, brown rice porridge, and honey (P ≤ 0.05). The release of calcium (mg/dL) into saliva from the tooth samples was observed to be highest following immersion in honey followed by ragi porridge, milk, and brown rice porridge [Table 4].
Table 2: Mean surface roughness (Ra) of enamel following immersion in saliva and test foods

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Table 3: Comparison of surface roughness between the groups

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Table 4: Calcium content in saliva (mg/dl) following immersion in saliva and test foods

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   Discussion Top

World Health Organization has recommended exclusive breastfeeding for 6 months, with introduction of complementary foods thereafter.[18] The process of introducing solid foods to infants by spoon is known as weaning.[19] Weaning practice can have a major influence on both immediate and future dental health, and good dietary practices from birth have the potential to secure a healthy dentition for life.[20] The aim of the weaning diet is to achieve a diet which fulfills nutritional requirements for the growing child and also contains a variety of foods and drinks. During the weaning period, mothers introduce different types of semi-solid foods into the diet of their infants and toddlers. Attention is given to nutritional value, texture, and digestive ability of the foods chosen for infant diets.

The Euro-growth study reported that fruits (73%) and cereals (51%) were the first foods given to most infants.[21] A Swedish study stated that most common first foods were vegetables, specifically potatoes, carrots, and sweet corn.[22] Commercially available cereals were the most common weaning foods in a Glasgow study.[23] All these diets are rich in carbohydrate and fiber. In developing countries, cereal-based diets are popular among mothers as they are commonly available at home as a part of traditional food practices and are also convenient to prepare. These cereal porridges are usually made from rice, wheat, or ragi (millet). Rice is the most important cereal in the South-East Asian countries. Home-made ragi malt is a popular infant food in India. Often during the preparation of these cereals, mothers add milk, ghee, sugar, or honey order to make these foods more palatable.

Pediatricians recommend feeding of cereals in the form of porridge to infants. Porridge is a semi-fluid food which is easy to chew, swallow, digest, and absorb.[24] Cereal porridges are often combined with large volumes of water and swell during cooking, making them very viscous.[25] Common cereal porridges consumed in Indian subcontinent include semi-solid preparations made of ragi, wheat, and brown rice. Apart from being rich in carbohydrates and fiber, these foods are source of other micronutrients also. Ragi is known for its high content of protein, calcium, iron, and phosphorus. Brown rice contains vitamin B complex and is rich in minerals such as magnesium, selenium, manganese, and potassium.[26] Brown rice is also rich in dietary fiber, antioxidants, and has a cardioprotective effect.[27],[28]

Cow's milk is given regularly to toddlers and children and is considered a healthy dietary practice. Foods and drinks containing milk have high levels of calcium and phosphate, so are likely to have a remineralizing effect on the dental enamel. Milk caused remineralization of the bovine enamel surface after an erosive challenge with chlorinated water in a recent study.[29]

Honey is a natural sweet substance, sticky, and viscous solution with a content of 80-85% of carbohydrate (mainly glucose and fructose).[30] It is also a good buffer (due to presence of phosphate, carbonate, and other mineral salts), and hence its pH does not change by addition of small quantities of acids or bases.[31] Honey is given to toddlers and children mainly as a sweetener and also for sustained energy. It has been used since ancient times and is a common cultural practice. Various studies have investigated the effect of milk and honey on the dentition.[32],[33] Due to their natural sugar content, milk and honey are cariogenic and may have erosive effect on teeth.[33] Another study stated that although honey has low pH and high sugar content, it caused less erosion on the enamel surface which might be due to the presence of calcium, phosphorus, and fluoride levels in its contents.[34] However, the effect of cereals per se on the primary dentition have been overlooked.

The inherent pH values indicate the initial hydrogen ion concentration but give no indication as to the presence of undissociated acid which has an erosive effect on teeth. The pH value identifies the erosive potential in the first few minutes of an erosion test, whereas the titratable acidity gives a measure of the total acid content of the beverage, thus better characterizing the erosive potential with longer exposure time.[35],[36],[37],[38]

In our study, the pH of honey was the lowest and the titrable acidity was high for ragi porridge and honey. Although porridge prepared with brown rice also had a semi-solid and sticky consistency, it had a low titratable acidity which was comparable to that of milk. In addition, milk is a liquid, which also has protective factors.

The enamel of primary teeth is relatively thin and has a higher pore volume than that of permanent teeth.[39] During early childhood, these newly erupted teeth can be susceptible to erosion on exposure to such foods. Semi-solid preparations using viscous sweeteners such as honey tend to adhere to the enamel surfaces of teeth. In the absence of optimal oral hygiene measures, they can be risk factors for dental caries. Therefore, it is vital to maintain the pH of the dental biofilm above the critical level.

Clinically, the surface roughness of enamel could be an early indication of dental erosion. Interestingly, highest surface roughness of enamel was observed with porridges prepared with millet (ragi) and brown rice. The coarse millet powder when cooked with milk and jaggery, with the presence of fiber in these semi-solid porridge preparations, may be the causative factor for increased roughness. The calcium release was high with millet porridge (ragi) which could be due to its high titratable acidity. However, enamel surface roughness caused by honey per se was lesser than that caused by both the porridge preparations.

At a microscopic level, surface roughness can be assessed by the loss of minerals such as calcium. Enamel consists of 34%–39% of calcium by weight (dry weight), and hence quantitative determination of the calcium dissolved through erosive procedure is an appropriate method to measure erosion.[40] These methods even measure the tiny amount of mineral loss. Due to the inherently low pH, high titratable acidity, and viscosity of honey, there was a high calcium release, indicating rapid demineralization of tooth structure. Honey has a higher viscosity than milk, making it adhere to tooth surfaces. However, there have been controversial reports on the ability of honey to cause dental caries.[30],[34] In our study, teeth samples immersed in honey showed less surface roughness values compared with other food items even if it had high calcium release into the saliva.

An earlier study in India compared the cariogenic potential of crushed brown rice with milk and jaggery (home-made weaning diet) with that of commercial formula feed. Lesser carious lesions were seen both clinically and histopathologically with the weaning diet compared with that of the commercially available diet.[41] However, this study evaluated only single home-made weaning food and the sweetening agent was jaggery, which had probably higher erosive effect than honey as seen in our study.

Caglar et al.[10] evaluated the erosive effect of different commercially available malt drinks on enamel in healthy subjects. They found statistically significant degree of erosion between the control group and the malt drink. However, the degree of erosion varied among different subjects. Another study[9] evaluated the erosive effects of chocolate milk, Petite swisse yoghurt, strawberry yoghurt, apple puree, and fermented milk which are the common foods given to children in Brazil. Except chocolate milk, (pH 6.41), all other food products were acidic and had pH significantly below the critical pH of enamel. Maximum mineral loss was seen with orange juice.

Dietary factors observed before the age of 1 year have been associated with severe early childhood caries at preschool age, emphasizing a need for timely, multilevel intervention.[42] Erosive potential of the foods can have detrimental effect on prolonged contact with enamel.

A sugar-rich diet is the key risk factor with detrimental consequences for general and oral health, particularly in combination with an insufficient oral hygiene. Primary care providers, gynecologists, and pediatricians have to be aware of the importance of oral health in infancy and possible consequences for child's development, growth, health, and quality of life.

   Conclusion Top

Porridges prepared from millet and brown rice cereal were seen to have an erosive effect on the enamel of primary teeth.


The authors cordially thank professor Dipshika Chakravorthy of the Department of Microbiology, Indian Institute of Sciences, for granting us permission to conduct our study in her laboratory; Mr. Akshay Datey, PhD student, Department of Microbiology, Indian Institute of Sciences, for his constant support, help, and interest in the study; Mr. Velpula Swamybabu and Mr. Ganesh for their valuable advice on optical profilometry and for technical support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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Correspondence Address:
Priya Subramaniam
Department of Pedodontics and Preventive Dentistry, The Oxford Dental College, Bommanahalli, Bengaluru - 560 068, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_224_18

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

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