Keep Smiling Dental Practice

Plaque is involved in the process of both dental caries and periodontal disease. Plaque is a soft, sticky film that forms on the surfaces of the teeth and it is packed full of bacteria and toxins. The first deposit to form on a clean tooth is the acquired pellicle. This is a film of glycoproteins from saliva which is formed within just a few minutes. This film is an open invitation for bacteria to come and stick to it and within about three hours, there will be considerable colonisation and the bacteria will continue to multiply unless the bacteria-packed film is removed. Plaque is mainly composed of bacteria and the toxins they produce, known as the matrix, and it equates to about 70%. If plaque is not removed from the teeth then it will absorb minerals from the saliva and turn into calculus, otherwise known as tartar.

Calculus is a very hard, stony substance. It is part crystalline and part calcium phosphate and has a high inorganic content (70-90%). Dental caries Dental caries is caused by the action of acids on the tooth surfaces. Bacteria found in plaque, especially streptococcus mutans, metabolise sugars and some other carbohydrates. The bacteria produce acid which attacks the tooth and any existing plaque holds the acid on contact with the tooth. The result of the acid attack is the loss of calcium and phosphate ions from the tooth- this is known as demineralisation.

The calcium and phosphate ions can be returned back to the tooth in order to repair it however this involves starving the plaque of any sugars. This is known as remineralisation. Caries forms and progresses if the demineralisation process occurs more rapidly than remineralisation. Early caries can often be halted and reversed if caught in time. Demineralisation starts beneath the surface of the enamel because enamel is so resistant to caries. At this point, it can be identified as a white spot lesion and the tooth can recover with treatment such as fluoride application, which will remineralise the tooth. If the caries is left to progress then the tooth will not be able to repair itself. The caries will either become arrested (stop progressing) or continue further. Frequency of sugar intake There is a very strong association between the frequency of sugar intake and caries. The most important sugars in the demineralisation process are the non-milk extrinsic (NME) sugars. These are sugars which are added to food and drink during manufacture and also at home. These sugars include sucrose (which we are most familiar with), dextrose, glucose, maltose and fructose. Lactose is also included however it is a sugar found in milk and is less likely to cause caries. The naturally occurring sugars which are found in fruit are known as intrinsic sugars and these are not as easily broken down by bacteria as the NME sugars.

Intrinsic basically means that the sugar is part of the cell wall. Fruit juice however is more harmful because the sugar has been separated from the cell wall and because of this, is easily metabolised. Fruit juice has NME rather than intrinsic sugars. What happens once NME sugar is consumed? On consumption, the plaque produces acid within one to two minutes, initiating demineralisation. This usually lasts for about twenty minutes but can last up to two hours. This is all dependent on the saliva flow and also the buffering ability of the saliva. Stephan’s curve is the name of a graph which depicts the fall in pH in plaque straight after the intake of a 10% glucose solution into the mouth. A similar fall is seen with other concentrations and other NME sugars in food and drinks. When the pH drops below the critical level of Ph (5.5), demineralisation takes place. Remineralisation occurs above this. Stephan’s curve also shows the comparison between somebody who has frequent sugar consumption and somebody who restricts sugar to mealtimes. The graph shows that frequent sugar intake keeps the Ph level below 5.5 for a considerable time.

Restricting sugar to mealtimes is nowhere near as harmful as there are only slight dips below 5.5 and there are longer repair periods in between. Educating patients about sugar frequency and dietary advice is very important and should always be specifically tailored to meeting the health needs of the patient. For example, a young child will need the help of a parent and may be advised to swap their bottle for a cup or dilute fruit juice when drinking at mealtimes. Effective dietary advice needs to be SMART- specific, measurable, achievable, realistic and time-related. Just like SMART is used in lesson planning, it needs to be used when giving one to one advice. Realistic aims and objectives should be set. For example, to advise a patient who has about 10 sugar intakes a day to totally cut out sugar from their diet is not sensible or realistic, it would be much more achievable to start by limiting sugar intakes to 5 a day. If the patient achieves this goal then they should be praised and encouraged to continue improving their oral health by limiting sugar even further. With help and support from their dental team, friends and family, the patient may well change their attitude and behaviour towards sugar. Acid erosion Acid erosion is caused by frequent or prolonged contact between the teeth and acidic food or drink. Plaque does not need to be present for erosion to take place. Vomiting or acid reflux can also cause erosion. Unfortunately, erosion is very common now with fizzy drinks and juice being as popular as they are. Erosion is normally painless however sensitivity to hot and cold is a side-effect. In order to reduce or prevent erosion, certain measures can be taken such as not washing fizzy drinks around the mouth and using a straw when drinking. Fluoride Fluoride application to tooth enamel increases the tooth’s resistance to caries.