The Influence of Salivary Factors on Dental Erosion

Edwards, Maura (2000) The Influence of Salivary Factors on Dental Erosion. PhD thesis, University of Glasgow.

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The Influence of Salivary Factors on Dental Erosion. Dental erosion appears to be an increasing problem in patients of all ages, with the rising incidence linked to the escalating consumption of soft drinks. The research discussed here has evaluated differences between various soft drinks. Variations between the salivary buffering capacity of normal individuals and subjects with erosion have also been identified. Most soft drinks are acidic and have a low pH value. However, pH determines only the free acid ions, whereas titratable acidity gives an indication of the total acid present in the drink. The acids in a drink also contribute to the drink's buffering capacity. Drinks with a higher buffering capacity resist the rise in pH that saliva attempts to bring about and, therefore, have the potential to keep the pH of the oral cavity lower for longer. Total acidity can be assessed by carrying out an acid-base titration. The slope of the graph, that is the total amount of alkali needed to bring about a rise in pH, gives an estimate of the buffering capacity of the drink. Several different groups of drinks have been tested. Carbonated drinks such as cola, which are not fruit-based, fruit-flavoured carbonated drinks such as Lilt, sparkling mineral waters, both plain and flavoured, still mineral water and pure fruit juices have all been included. The initial pH values showed cola drinks to have the lowest pH and still mineral water the highest. Significant differences in buffering capacity were found between each of the groups of drinks tested. The total acid found in fruit juices and fruit- based drinks was far greater than that found in cola drinks. It is clear that the addition of fruit flavouring, and hence more acid, to drinks increases their buffering capacity. This was despite the fact that the initial pH values of the fruit juices were higher than the cola drinks, indicating that pH values alone do not predict accurately the total amount of acid present in a drink. Caution must be exercised, however, when extrapolating these results to the oral cavity, but it is clear that in terms of acid content, fruit drinks and fruit juices have more potential demineralise tooth tissue. In the mouth, saliva becomes a major modifying factor, as it neutralises and buffers acidic substances and acts in effect as a biological base. By carrying out titrations of saliva with soft drinks, it can be seen how effective saliva is at coping with the challenge of acidic drinks. Drinks from each of the main groups were titrated with saliva from various volunteers. Again, clear differences were seen between the various groups of drinks, with pure fruit juices causing the greatest changes in salivary pH, followed by fruit - based carbonated drinks. Carbonated cola drinks and sparkling mineral waters caused smaller changes in salivary pH. Saliva was also collected from volunteers with diagnosed dental erosion. It was interesting to note that the pH of saliva from those with erosion fell more quickly than that of normal individuals. Saliva from individuals with erosion may, therefore, be less able to cope with the acidic challenge of soft drinks. The oral cavity is a dynamic physiological model. There are many complex factors involved in the interactions of saliva with acidic drinks, which in vitro experiments only go some way to explaining. The monitoring of salivary pH during drinking involved observing changes in pH while consuming an entire can of beverage. A measured sip of the chosen soft drink was taken every minute, with saliva being collected shortly after each sip for pH measurement. Three different drinks were tested, including a pure fruit juice and a diet drink. For most of the volunteers, salivary pH fell during drinking. There were a few individuals for whom the pH values of saliva rose during drinking, highlighting the excellent ability of saliva as a buffering agent. However, the most common finding was a fall in salivary pH, which often extended beyond the drinking time, indicating that the effects of soft drinks on the saliva may continue for some time after drinking has stopped. It was felt important to include patients with diagnosed erosion in this trial, to see how their saliva reacted to an erosive insult. The fall in salivary pH was particularly marked for these volunteers with erosion. Once again, it emerged that there may be some deficiency in the saliva of those who are prone to erosion, in that the buffering capacity of the saliva appeared to be reduced. There were also differences between the various drinks tested. Consumption of the pure fruit juice caused the pH of saliva to fall to a lower value than when the cola drink was taken. These results underline the results from the earlier in vitro tests, indicating that pure fruit juices may have more potential to cause erosion because of their ability to lower the pH of the oral cavity for longer. There is evidence that many factors contribute to the buffering ability of saliva. Salivary proteins are believed to play a role, especially at extremes of acidity.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Steve Creanor
Keywords: Dentistry
Date of Award: 2000
Depositing User: Enlighten Team
Unique ID: glathesis:2000-74889
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 27 Sep 2019 15:29
Last Modified: 27 Sep 2019 15:29

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