The effect of alpha-amylase enzyme activity in the oral cavity on the incidence of dental caries in early childhood

*Corresponding author: Atsilah Matta Ibrahim. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. The effect of alpha-amylase enzyme activity in the oral cavity on the incidence of dental caries in early childhood Atsilah Matta Ibrahim 1, *, Aeeshah Aswi Akbar 1, Maretha Putri Surya Mahendra 1, Tantiana 2 and Ratri Maya Sitalaksmi 3 1 Faculty of Dental Medicine, Airlangga University, Surabaya, East Java, Indonesia. 2 Department of Oral Biology, Faculty of Dental Medicine, Airlangga University, Surabaya, East Java, Indonesia. 3 Department of Prosthodontics, Faculty of Dental Medicine, Airlangga University, Surabaya, East Java, Indonesia. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 Publication history: Received 08 October 2025; revised on 15 November 2025; accepted on 18 November 2025 Article DOI: https://doi.org/10.30574/wjbphs.2025.24.2.1014 Abstract Background: Oral hygiene is assessed, among other things, by determining the accumulation of dental plaque. Plaque caused by bacteria erodes hard tooth tissue and causes caries. Dental caries is highly prevalent in early childhood. The WHO notes that around 514 million children worldwide suffer from caries. The Basic Health Research results show that the incidence of caries in early childhood in Indonesia reached 93% in 2018. The lack of parental knowledge regarding oral hygiene in children aged 1–6 years in Indonesia is reflected in the high caries rate. A factor that still causes caries is the activity of the alpha-amylase enzyme. Alpha-amylase is the most abundant enzyme in the oral cavity, produced by the salivary glands, and functions to aid in the digestion of food by hydrolyzing starch into glucose and maltose. This enzyme regulates bacterial colonization and adds glucose for biofilm formation. On the other hand, proteins found in saliva have a protective and bactericidal mechanism against cariogenic bacteria, thereby reducing the risk of dental caries. Objective: To determine the effect of alpha-amylase enzyme activity in the oral cavity on the incidence of caries in early childhood. Methods: The method used in this paper is a literature review. Data sources were searched using Google Scholar and PubMed. The literature selected was based on previous research and thought, which was then extracted, analyzed, and synthesized. Results: Lower levels of alpha-amylase enzyme activity make individuals more susceptible to dental caries. In young children with caries, alpha-amylase enzyme activity is higher during caries growth. Conclusion: Salivary alpha-amylase activity alone cannot be used as a definitive indicator of caries risk in young children, as it must be interpreted alongside other contributing factors. Keywords: Caries; Early Childhood; Alpha-amylase; Saliva 1. Introduction Oral health problems such as dental caries are conditions in which hard tooth tissue undergoes demineralisation due to bacteria. Dental caries are very common among people, especially children aged 1-6 years. Dental caries in childhood are the most common chronic infectious disease in children and are a public health problem in many countries around World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 433 the world [1]. According to [2], an estimated 514 million children worldwide suffer from dental caries. This prevalence continues to increase with urbanisation and lifestyle changes. Based on the results [3], the prevalence of dental caries in childhood is still very high, at around 93%. This means that only 7% of Indonesian children are free from dental caries. Caries in early childhood is progressively caused by an imbalance of various risk factors, including supporting factors that are often associated with socioeconomic, psychological, and parental behaviour factors. Its high prevalence is caused by incorrect feeding methods, inadequate parental knowledge, family socioeconomic status, and lack of dental care. This is because many parents have inadequate knowledge and lack awareness of their children's health issues, resulting in high rates of health problems among young children. Other factors that have recently been investigated show a link between the chemical structure of saliva and its protective mechanism against dental caries. The most abundant enzyme in human saliva is alpha-amylase, which plays a role in hydrolysing starch into glucose and maltose and aids in food digestion. This enzyme regulates bacterial colonisation and adds glucose for biofilm formation. However, on the other hand, this protein also binds to the membranes of cariogenic bacteria and helps eliminate these bacteria from the oral cavity through saliva cleansing, thereby reducing the risk of dental caries [4]. There are several contradictory studies on the relationship between alpha-amylase enzyme activity and the incidence of caries. Several studies have discussed the relationship between alpha-amylase and caries, but the results are inconsistent. Therefore, researchers are interested in investigating the effect of alpha-amylase enzyme activity in the oral cavity on the incidence of caries in early childhood. 1.1. Digestion Process in the Oral Cavity The human digestive system is a system in the body that acts as a receiver of food from outside, which is then processed in the human digestive organs, starting from receiving food from outside, digesting it, and absorbing absorbable substances. The first stage of digestion takes place in the oral cavity. In the oral cavity, food undergoes mechanical and chemical digestion. Mechanical digestion refers to the process of breaking down large food particles into smaller ones. This mechanical digestion is carried out by the teeth in the oral cavity. The teeth crush food through the process of chewing. Chemical digestion also occurs in the oral cavity, meaning that the digestive process is carried out using chemical substances, known as enzymes. Enzymes are capable of converting complex chemical compounds in food into simpler compounds. Enzymes act as catalysts, which means they assist chemical processes by lowering the activation energy. If the activation energy of a chemical process is low, the product will be easier to produce [5]. 1.2. Oral Cavity The oral cavity, more commonly known as the mouth or buccal cavity, serves as the first part of the digestive system. The oral cavity consists of several different anatomical aspects that work together effectively and efficiently to perform several functions. These aspects include the lips, tongue, palate, and teeth. Despite its small size, the oral cavity is a unique and complex structure with several different nerves and blood vessels inside it. This complex network is necessary for its unique and diverse roles in human life [6]. The oral cavity is surrounded by the lips and consists of two separate areas: the anterior space, the area between the cheeks, teeth, lips, and the actual oral cavity. The actual oral cavity is mostly occupied by the tongue and is bounded at the front and sides by the alveolar process containing the teeth and at the back by the isthmus of the fauces. In the superior part, it is formed by the hard palate in the anterior and the soft palate in the posterior. The uvula hangs down from the soft palate. The mylohyoid muscle forms the base of the actual oral cavity. The mucous membrane, known as the oral mucosa, consists of stratified squamous epithelium and forms the inner lining of the mouth. Several submandibular and sublingual salivary glands secrete thick, mucous fluid to lubricate and keep the oral cavity moist [6]. The mouth plays an important role not only in the initial intake of food and water for digestion, but also in normal speech and breathing functions. Teeth, which are the main structures of the oral cavity, shred and grind food into small pieces so that it can be easily digested by other organs. The tongue aids in the digestion of food by moving it to the roof of the mouth; this leads to the formation of a food bolus which is then swallowed by the esophagus. The tongue also functions to provide humans with a sense of taste because it contains various papillae on its surface that act as taste buds. In addition, the tongue is the most important articulator in speech, as it manipulates itself with the teeth and palate to form words. The palate functions as a mechanical barrier that separates the oral cavity from the nasal respiratory tract [6]. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 434 2. Caries Caries is a progressive dental abnormality that begins with demineralization caused by acids produced by bacteria and is the main cause of tooth loss. Caries occurs when Streptococcus mutans and Lactobacillus bacteria are present, which are capable of producing acids that demineralize tooth structure [7]. Dental caries occurs due to the demineralization of tooth structure by acids produced by microorganisms and is characterized by the formation of cavities on the surface of the enamel, dentin, or cementum. The progression of caries is chronic, cannot heal on its own, and can eventually lead to tooth loss if left untreated [7]. Cavities occur as a result of demineralization by acids produced by bacterial metabolism in plaque, which converts carbohydrates into energy and organic acids. Demineralization occurs when the pH reaches 5.0-5.5. Demineralization can be inhibited if the pH is >5.5, which can be achieved through the saliva buffer system, dietary modifications, or fluoridation. At a pH >5.5, the process of remineralization of the tooth structure occurs, which is when minerals replace the enamel surface that has undergone demineralization. The processes of demineralization and remineralization will occur alternately [7]. Caries classification is divided based on the initial location of caries occurrence, such as : 2.1. Pit and Fissure Caries In this type of caries, caries begins on the occlusal surface of posterior teeth. Over time, this type of caries has been renamed occlusal caries based on its anatomical location. The long and narrow pits and fissures on the occlusal surface of posterior teeth make it difficult to reach these areas when cleaning teeth with a toothbrush. This structure becomes the main place for bacteria to grow, especially gram-positive Streptococcus mutans bacteria. 2.2. Smooth Surface Caries The smooth surface of the tooth is the most difficult surface for plaque to adhere to. Plaque usually adheres to areas near the gingiva or below the proximal contact point, which is an ideal place for cariogenic bacteria to grow. Due to the effects of chewing, tongue movement, and saliva flow, the surface of the tooth becomes increasingly rough. This rough surface makes it easy for plaque to adhere, leading to caries. 2.3. Root Caries This type of caries occurs on the roots of teeth. As with caries on other surfaces, the rougher the root surface, the easier it is for plaque to adhere. In addition, tooth roots are only covered by a thin layer of cementum, making them susceptible to caries. 2.4. Early Childhood Early childhood refers to children aged 0-6 years, as defined in Article 28 paragraph 1 of Law No. 20/2003 on National Education. At this age, children are still under the strong monitoring of their parents, so their growth and development are highly dependent on their parents' parenting style. From the womb to the early years of life is referred to as the golden age, during which the brain develops and nerve cells mature at a rapid pace. The golden age is a crucial period for children's physical, psychological, cognitive, and social development. Teaching and accustoming children as early as possible will have a positive impact on their future development. Early childhood is the most optimal period for stimulating individual development, so this phase should not be wasted. Stimulation provided to optimize development in early childhood will influence a child's development throughout their life. Parents play a crucial role in educating and guiding children in early childhood to shape their habits and personality holistically. The development of each individual cannot be measured, but it can be perceived. The speed of an individual's development is influenced by various factors such as stimulation, nutrition, health, environment, and various other factors [8]. Some developments in early childhood include moral and religious development, social-emotional development, cognitive development, language development, physical-motor development, and creativity development. Parents, as the first educators, must be able to develop their children's cognitive, affective, and psychomotor abilities. It is important to develop cognitive (knowledge), affective (attitude), and psychomotor (skills) aspects. This is because World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 435 early childhood is a golden period for child development, with 50% of intelligence development occurring between the ages of 0 and 4, and the next 30% occurring up to the age of 8 [9]. If there are developmental delays, appropriate intervention is needed to prevent negative impacts in the future. Therefore, the role of parents in educating their children is very important. 2.5. Salivary alpha-amylase enzyme The alpha-amylase enzyme functions as a catalyst in the hydrolysis reaction of starch to form glucose and maltose. This enzyme has the chemical name endo-1,4-alpha-D-glucan glucohydrolase. Alpha-amylase enzyme is composed of a protein consisting of 3 domains. Alpha-amylase enzyme has the properties of calcium metalloenzymes, so it cannot function without calcium ions [1]. Most α-amylase enzymes break down long-chain carbohydrates endoamylase. However, there are some α-amylase enzymes that break down carbohydrates exoamylase. The results of α-amylase breakdown are dextrin, limit dextrin, oligosaccharides, and cyclodextrin derivatives. α-amylase enzymes that produce dextrin endoamylase come from human saliva and pancreas, pig pancreas, wheat, fungi (Aspergillus oryzae and Rhizopus niveus), thermostable bacteria (Bacillus subtilis, Bacillus licheniformis, Bacillus acidocaldarius, Clostridium, Dictyoglomus thermophilum, and Bacillus stearothermophilus), as well as other bacteria such as Streptococcus bovis . Salivary alpha-amylase (SAA) is a type of amylase enzyme found in human saliva that is produced locally in the oral mucosa. In addition to breaking down starch, this enzyme is also known as a marker of adrenergic components in response to stress. Salivary alpha-amylase is thought to reflect changes in the autonomic nervous system. The release of SAA is known to be due to the activation of the autonomic nerves that control the salivary glands. Salivary alpha-amylase enzymes play an important role in bacterial interactions. Alpha-amylase is known to bind to oral Streptococcus groups, allowing salivary amylase enzymes to function as bacterial removers. Salivary alpha-amylase is one of the components in acquired enamel pellicle and acts as a receptor for bacterial adhesion to tooth surfaces. The binding of alpha-amylase to bacteria and teeth has important implications for plaque formation and caries. Salivary amylase levels vary among individuals. This variation is caused by a number of environmental factors, including stress levels, circadian rhythms, and various other physical conditions. The rate of amylase enzyme activity is influenced by numerous factors, one of which is nutritional status, as well as other systemic conditions. Poor nutritional status can affect secretion and composition in saliva, causing a decrease in saliva flow rate and changes in amylase enzyme activity. 3. Material and Method The method used in this paper is a literature review. Data sources were collected through Google Scholar, PubMed, and other databases. The selected literature consisted of previous research findings and scholarly works, which were then extracted, analyzed, and synthesized. A comprehensive search of electronic databases was conducted to identify relevant studies published within the last ten years. 4. Result and Discussion Early childhood caries is a health problem with multiple contributing factors, which vary among individuals. Dental caries is significantly associated with dietary habits and tooth-brushing behavior. The consumption of carbohydrates and sugars has been proven to contribute to the development of caries. In addition, improper eating practices, lack of parental education, and poor oral hygiene can increase the risk of early childhood caries. The main factor in the development of dental caries is the production of acidic fermentation products from carbohydrates by bacteria found in saliva and dental plaque. Cariogenic bacteria in humans are most commonly represented by Streptococcus mutans, Streptococcus viridans, and Streptococcus sobrinus, with S. mutans generally regarded as the primary causative agent of dental caries. For pathogenic plaque formation to occur, oral microbial adhesion to the tooth surface must take place. Saliva plays a crucial role in controlling this adhesion due to its protein content—especially glycoproteins—which contribute to the formation of the acquired enamel pellicle. The pellicle itself contains specific attachment sites for oral microflora. The quantity and quality of salivary components vary among individuals, contributing to differences in early childhood caries susceptibility. Salivary alpha-amylase is an important enzyme that can inhibit several biological activities related to its ability to bind cariogenic bacteria and metabolize carbohydrates. Salivary alpha-amylase binds to cariogenic World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 436 bacteria and facilitates their elimination from the oral cavity, thereby reducing the risk of caries. This theory aligns with the findings of [1], who reported that the average salivary alpha-amylase activity was higher in children without caries. Similarly, research by [10] found that salivary alpha-amylase activity in caries-free children was higher than in those with caries. Therefore, low salivary alpha-amylase activity can be considered a predictive risk factor for early childhood caries. Conversely, research by [11] found contradictory results, showing that children with active caries exhibited higher salivary enzyme activity than caries-free children. This study was conducted on children aged 10–14 years. A similar pattern was observed regarding the concentration of salivary alpha-amylase. It appears that excessive salivary alphaamylase concentration leads to the hydrolysis of dietary starch into maltose, which can be utilized by cariogenic bacteria to produce acids—thus increasing the risk of dental caries. One possible explanation for these varying findings is that human saliva consists of water, electrolytes, mucus, glycoproteins, enzymes, and antibacterial compounds such as immunoglobulins and lysozymes. Under such complex conditions, assessing the effect of one component while disregarding others can lead to inconsistent results due to confounding effects from other salivary elements. Recent research by [12] on salivary microbiota and metabolomic analysis in early childhood caries concluded that excessive carbohydrate intake can alter the oral microenvironment and facilitate caries induction by cariogenic bacteria. Children with lower levels of salivary alpha-amylase activity are more susceptible to dental caries, and this risk is further exacerbated by poor nutrition and inadequate oral care [1]. Human saliva acts as a medium for transferring various protective proteins that play key roles in the prevention, initiation, and progression of dental caries. Therefore, salivary alpha-amylase may have both protective and detrimental properties. The relationship between alpha-amylase activity and early childhood caries incidence cannot be determined without considering other contributing factors. Evaluating salivary alpha-amylase levels may serve as a useful method for identifying individuals at high risk of dental caries, as enzyme levels are often elevated in patients with active caries. Systematic caries detection methods and further risk management studies could help reduce caries incidence and halt disease progression. 5. Conclusion The alpha-amylase enzyme influences the incidence of early childhood caries because it is present in saliva, which serves as a natural defense mechanism against caries. However, alpha-amylase is not always beneficial in this context. Excessive concentrations of salivary alpha-amylase lead to the hydrolysis of dietary starch into maltose, which cariogenic bacteria can utilize to produce acids. Low enzyme activity levels increase caries susceptibility. During caries development in early childhood, alpha-amylase activity tends to rise. Nevertheless, alpha-amylase cannot be directly linked to caries incidence in early childhood, as many other factors contribute to caries development. Compliance with ethical standards Acknowledgments The authors would like to express their deepest gratitude to Tantiana, DDS., M.H, for the continuous guidance, valuable advice, and constructive feedback throughout the preparation of this article. Sincere appreciation is also extended to the Faculty of Dentistry, Airlangga University, for providing the facilities and academic support that made this work possible. The authors would also like to thank the lecturers and staff of the Department of Oral Biology for their encouragement, as well as all previous researchers whose studies became the scientific foundation of this literature review. Lastly, the authors are deeply grateful to their families and peers for their endless support and understanding during the completion of this paper. Disclosure of conflict of interest Authors have declared no conflict of interests. Statement of ethical approval This article is a literature review and does not involve any direct experimentation on human participants or animals. Therefore, formal ethical approval was not required. World Journal of Biology Pharmacy and Health Sciences, 2025, 24(02), 432–437 437 References [1] Parsaie Z, Rezaie P, Azimi N, Mohammadi N. Relationship between Salivary Alpha-Amylase Enzyme Activity, Anthropometric Indices, Dietary Habits, and Early Childhood Dental Caries. Gadbail A, editor. International Journal of Dentistry. 2022 Mar 26;2022:1–7. [2] World Health Organization. Oral Health [Internet]. World Health Organization. 2025 [cited 2023 Mar 14]. Available from: https://www.who.int/news-room/fact-sheets/detail/oral-health [3] Kementerian Kesehatan RI. 2018. Laporan Nasional Riskesdas 2018. Jakarta: Badan Penelitian dan Pengembangan Kesehatan. 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