What are cavities?

Cavities, also known as dental caries or tooth decay, are small holes or openings that develop in the hard surface of the teeth. They occur when bacteria in the mouth produce acids that gradually dissolve and damage the outer layer of the teeth, called enamel. If left untreated, cavities can progress deeper into the tooth, affecting the dentin (the layer beneath the enamel) and potentially reaching the tooth’s pulp, where nerves and blood vessels are located.


Cavities can form in any part of the tooth, but they often develop in areas where food particles and plaque (a sticky film of bacteria) accumulate, such as the pits and fissures on the chewing surfaces, between teeth, and along the gumline.


What is the relationship between cavities and oxidative stress?

The relationship between cavities (dental caries or tooth decay) and oxidative stress is multifaceted, involving various mechanisms related to the role of oxidative stress in oral health and the progression of dental caries. Here’s how cavities and oxidative stress are interrelated:


  • Bacterial Acid Production: The primary cause of cavities is the activity of bacteria in the mouth, particularly Streptococcus mutans and other acidogenic bacteria. These bacteria ferment dietary carbohydrates (sugars and starches) to produce acids, particularly lactic acid. The acids created during this process lower the pH in the oral cavity, leading to an acidic environment that can demineralize tooth enamel and promote cavity formation. Oxidative stress can modulate the activity and virulence of oral bacteria, potentially influencing the production of acids and the progression of dental caries.


  • Oxidative Damage to Tooth Structure: Oxidative stress in the oral cavity can lead to damage to the structure of the teeth, particularly the enamel. Reactive oxygen species (ROS), such as hydrogen peroxide and superoxide radicals, can directly damage tooth enamel by oxidizing its organic components and disrupting its mineral structure. This oxidative damage weakens the enamel and makes it more susceptible to demineralization and decay by acid-producing bacteria.


  • Inflammation and Immune Response: Oxidative stress can stimulate inflammation in the oral tissues, including the gums (gingiva) and periodontal ligament. Inflammatory processes in the gums can lead to gingivitis (inflammation of the gums) and periodontitis (inflammation of the supporting structures of the teeth), which can contribute to the progression of dental caries. Additionally, oxidative stress can modulate the immune response in the oral cavity, influencing the activity of immune cells involved in host defense against oral pathogens.


  • Antioxidant Defense Mechanisms: The oral cavity contains various antioxidant defense mechanisms that help counteract oxidative stress and maintain oral health. Antioxidants such as vitamin C (ascorbic acid), vitamin E (alpha-tocopherol), and glutathione play a crucial role in scavenging ROS and protecting oral tissues from oxidative damage. Dysregulation of antioxidant defense mechanisms in the oral cavity can contribute to oxidative stress and increase the risk of dental caries.


  • Salivary Antioxidants: Saliva contains natural antioxidants, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, which help neutralize ROS and maintain oral health. Changes in salivary antioxidant levels or activity can affect the oral microbiota and contribute to oxidative stress-related oral diseases, including dental caries.


Overall, oxidative stress is implicated in the pathogenesis of dental caries by promoting bacterial acid production, oxidative damage to tooth structure, inflammation, and dysregulation of antioxidant defense mechanisms.