The buffer capacity and buffer systems of human whole saliva measured without loss of CO2 Original paper

What was studied?

This study examined the buffer capacity and buffer systems of human whole saliva under conditions designed to minimize the loss of CO2, a significant factor in the accuracy of saliva pH and buffering capacity measurements. The researchers focused on unstimulated and stimulated saliva from 20 healthy volunteers, measuring key components such as bicarbonate (HCO3), phosphate, and protein concentrations, and their contributions to saliva’s overall buffer capacity. The study also assessed the impact of saliva flow rates, pH variations, and the depletion of CO2/HCO3 from saliva on its buffering ability.

Who was studied?

The study involved 20 healthy volunteers, including 9 males and 11 females, with a mean age of approximately 27 years. All participants were in good health and did not take any medication during the study. They were asked to refrain from eating, drinking, and oral hygiene for two hours before saliva collection. The research was conducted at the University of Copenhagen, with saliva samples taken under conditions that minimized CO2 loss.

What were the most important findings?

The study found that the buffer capacity of whole saliva depends heavily on the bicarbonate concentration, saliva flow rate, and pH level. Stimulated whole saliva (SWS) had a higher buffer capacity than unstimulated whole saliva (UWS), particularly at pH levels ranging from 5.25 to 7.25, which is close to the physiological pH range of the mouth. Bicarbonate was identified as the primary contributor to the buffer capacity, especially in SWS. The buffer capacity of both UWS and SWS was significantly reduced when CO2/HCO3 was depleted from the samples, highlighting the essential role of this buffer system. Additionally, the study observed that increasing saliva flow rates led to higher bicarbonate concentrations and an alkaline pH, which in turn increased the buffer capacity. The contribution of the protein buffer system was significant at acidic pH levels (below pH 5), but less impactful at higher pH levels.

What are the greatest implications of this study?

The findings of this study underscore the importance of bicarbonate in maintaining the buffering capacity of saliva, particularly in the context of oral health. The ability to manage and measure saliva’s buffer capacity has direct implications for understanding how saliva protects the teeth and oral mucosa from acid-induced damage, such as from dietary acids or bacterial metabolism. This knowledge could improve clinical practices in areas like caries prevention, where buffering capacity plays a role in reducing the risk of tooth demineralization. Additionally, the study highlights the role of saliva flow rate and pH in influencing saliva’s buffering ability, which could inform therapeutic strategies for patients with dry mouth (xerostomia) or those at risk of dental decay due to insufficient salivation. It also provides valuable insight into the impact of CO2 loss on saliva measurements and suggests improved methods for more accurate saliva analysis in clinical and research settings.