Bentonite clay is a naturally occurring material formed from the weathering of volcanic ash, often used in beauty and detoxification routines. Dental remineralization is the natural repair process where minerals are redeposited into tooth enamel to reverse early decay. This article investigates the established science of tooth repair against the claims made for bentonite clay to determine its efficacy in strengthening teeth.
Understanding Tooth Demineralization and Repair
Tooth enamel, the hardest substance in the human body, is primarily composed of crystalline structures of hydroxyapatite. This structure is constantly engaged in a dynamic exchange with the oral environment, balancing between mineral loss and gain. Demineralization occurs when the pH level in the mouth drops below a critical threshold, typically around 5.5, often due to acids produced by oral bacteria metabolizing sugars.
During an acid attack, hydrogen ions dissolve the hydroxyapatite crystals, causing calcium and phosphate ions to leach out of the enamel. Saliva helps reverse this process by acting as a buffer, neutralizing the acid and raising the pH back to a neutral level. Remineralization occurs when the environment is no longer acidic, allowing the calcium and phosphate ions present in the saliva to be reincorporated into the demineralized enamel structure. This repair mechanism helps teeth maintain integrity and resist the progression of early lesions into irreversible cavities.
Composition and Proposed Mechanism of Bentonite Clay
Bentonite clay is a phyllosilicate mineral, mainly composed of montmorillonite, which gives it a unique layered structure. This volcanic ash derivative is rich in various essential minerals, including calcium, magnesium, potassium, and silica. When mixed with water, the clay swells and develops a strong net negative electrical charge.
Proponents of its dental use suggest two primary mechanisms for oral health benefits. The first is its ability to cleanse the mouth due to its negative charge, which allows it to attract and bind to positively charged particles like bacteria, plaque, and other impurities. The clay is thought to act like a sponge, absorbing these substances and helping to remove them during rinsing or spitting. The second proposed benefit is its mineral-rich composition, suggesting that the calcium and magnesium in the clay are available to be absorbed by the enamel to support remineralization.
Scientific Evidence on Remineralization Efficacy
Despite the presence of calcium and other minerals, direct clinical evidence demonstrating that bentonite clay actively remineralizes teeth is largely absent. The remineralization process requires minerals to be in a highly bioavailable ionic form so they can be effectively taken up and integrated into the damaged enamel structure. The minerals within the clay’s complex crystalline structure are often not readily released into the saliva in the necessary concentrations or forms to facilitate this repair.
Established remineralizing agents, such as fluoride, work by promoting the formation of fluorapatite, a crystal structure more resistant to acid than natural hydroxyapatite. Synthetic nano-hydroxyapatite, another agent, consists of nanoparticles nearly identical to the natural enamel component, allowing it to integrate directly into demineralized areas. These substances have been extensively studied in clinical trials showing measurable efficacy in reversing early decay. Bentonite clay’s primary benefit in oral care is its absorbent and mild antibacterial properties, which may help manage the oral environment but do not constitute a restorative effect. Reviews of literature on bentonite clay products have struggled to find supportive data for benefits related to tooth decay, with some studies even suggesting potential harm.
Safety Considerations for Dental Applications
The use of bentonite clay for dental applications introduces practical risks that warrant careful consideration. A significant concern is the potential for heavy metal contamination, specifically lead, arsenic, and mercury, which can naturally occur in clay deposits. The U.S. Food and Drug Administration (FDA) has issued warnings regarding elevated levels of lead in some bentonite clay products.
While manufacturers often claim that these metals are bound within the clay and are not bioavailable, studies suggest that heavy metals can be absorbed through the oral mucosa or ingested, posing a health risk. There is no established safe level for lead ingestion, and its presence in an oral product is a serious issue. Another safety consideration is the physical texture of the clay. Although some sources suggest a low abrasiveness, the abrasive nature of any powder can still physically wear down enamel and soft gum tissue over time, leading to erosion. This physical wear can counteract claimed benefits and cause permanent damage.