Nutrition plays an important role in tooth formation and development as well as in bone development and metabolism. It may also be involved in disease processes affecting the tooth and its supporting structures. While there is currently no known single nutrient or combination of nutrients that will prevent the development of periodontal disease, deficiencies of many nutrients are thought to be linked to the development and progression of both gingivitis and periodontitis. In addition, the texture of the diet will affect accumulation of dental deposits and thus gingival health.
AETIOLOGY AND PATHOGENESIS OF PERIODONTAL DISEASE
The primary cause of gingivitis and periodontitis is accumulation of plaque on the tooth surfaces. Calculus (tartar) is a secondary etiologic factor. The pathogenesis of periodontal disease is by no means fully elucidated. The plaque bacteria and their products, as well as the inflammatory and immune reactions of the host, contribute to the destruction of the periodontium.
The pathogenic mechanisms involved in periodontal disease include:
Direct injury by plaque microorganisms.
Indirect injury by plaque microorganism via inflammation.
Although numerous microbiological studies have been performed, the association between specific periopathogens and periodontitis remains to be conclusively proven. It is not yet possible to state whether the microbiota found in deep periodontal pockets where supporting structures have been destroyed are the cause or an effect of periodontitis. Many microbial products have little or no direct toxic effect on the host; instead they possess the potential to activate non-immune and immune inflammatory reactions. It is these inflammatory reactions that actually cause the tissue damage.
In summary, it is not yet possible to entirely account for the pathogenesis of periodontal disease. The dog has, for the last thirty years, been used as the experimental model for human periodontal disease. Despite this, we still do not fully understand the mechanisms involved in disease development in either species. It is now well accepted, however, that it is the host's response to the plaque bacteria rather than microbial virulence that directly causes the tissue damage.
Undisturbed plaque accumulation will result in gingivitis. However, not all animals with untreated gingivitis will progress to periodontitis. Clinically healthy gingivae can be maintained by frequent, usually daily, plaque removal. In man, the single most effective means of removing plaque is frequent, preferably daily, tooth brushing. This has also been shown to hold true for the dog.
Animals with clinically healthy gingivae will not develop periodontitis. Untreated gingivitis will, in some individuals, progress to periodontitis. At our current level of knowledge, we cannot predict which individuals with gingivitis will develop periodontitis.
THE EFFECT OF DIETARY TEXTURE
The relationship between dietary texture and the accumulation of plaque and development of gingivitis has not been clearly demonstrated in humans, although a link has been determined in dogs. It has been proposed that differences seen between studies in man and dogs may be due to the different tooth anatomy, i.e., dog teeth are more tapered which may allow for more efficient cleaning of the tooth surface through chewing. While fibrous foods may help to remove plaque from chewing surfaces, the area around the gingival margin (the important area for the initiation of periodontal disease) is not efficiently cleansed by chewing.
Several workers have investigated the effect of the daily addition of raw apples or carrots to the diet on gingival health in man. With the exception of one study that showed a reduction in gingivitis, others showed no beneficial effect being derived from the addition of these foods. Several recent studies have investigated mechanical means of reducing accumulation of dental deposits (plaque and calculus) via dietary texture in the dog. These modified dry diets and dental hygiene chews do reduce the accumulation of plaque and calculus and the severity of gingivitis. They do not maintain clinically healthy gingivae in the absence of tooth brushing. Moreover, it has yet to be demonstrated that reducing the severity of gingivitis will necessarily prevent the development of periodontitis.
Aside from mechanically cleaning the teeth, food that encourages chewing will also stimulate salivary flow. Saliva contains anti-bacterial agents that help keep the mouth clean. It has also been speculated that chewing helps strengthen the alveolar bone and periodontal ligament thus reducing the risk of developing periodontitis. However, the evidence to support this theory is lacking.
The primary cause of periodontal disease is the accumulation of plaque on the tooth surfaces. However, possible nutritional influences on the development and progression of disease may occur. Mechanisms by which nutrition may affect periodontal disease include:
1. Anti-Microbial Action. Many nutrients have anti-microbial activity. These may alter the quantity and/or quality of dental plaque and thus be associated with a reduction in gingival inflammation.
2. Anti-Inflammatory Effect. Nutrients that decrease the host response to injury may result in a reduction in the severity of gingivitis and/or development and progression of periodontitis. These work by affecting the enzymes involved in the production of the anti-inflammatory compounds or by altering which compounds are actually produced.
3. Immune System Modification. Some nutrients are thought to act as immune system modifiers in that they optimise the host’s immune response so that the protective immune reactions outweigh the self-destructive ones. This could also be accomplished by alteration of the permeability of the gingival epithelium, thus changing host resistance to bacterial products.
4. Anti-Oxidant Effect. Nutrients with an anti-oxidant action help maintain cell integrity by reducing the free radical damage to host tissues that is initiated by the host’s inflammatory and immune reactions. They also serve to protect the host from bacterial damage.
Research to date shows that deficiencies of several nutrients have an effect on the development and progression of periodontal disease. On the other hand, there is no conclusive evidence that supplementation of any nutrient above and beyond required levels has an effect on the development of periodontal disease. Interestingly, the development of periodontal disease can have a profound effect on nutritional status of the individual. Pain and loss of teeth can affect the emotional well-being of the individual and will also affect the food choices made. This can result in the development of nutritional deficiencies and/or severe malnutrition that are even more detrimental to the affected individual. It should be emphasized that there is no known nutritional intervention that can be used as a substitute for daily tooth brushing and regular dental check-ups. Balanced nutrition should be used in conjunction with an effective dental hygiene program to reduce the risk of developing periodontal disease.
Dietary texture has been shown to influence accumulation of dental deposits in the dog, although such a link has not been established in man. Nutritional deficiencies have been shown to affect periodontal disease primarily by altering the host response to plaque, but no nutrient will prevent disease development or progression. Supplementation of nutrients has not been shown to affect disease, although several, including folic acid and vitamin C, warrant further investigation. The combination of a well balanced diet, regular dental examinations and cleanings, and a good home dental hygiene program will reduce the risk of developing periodontal disease in man and animals.
REFERENCES ARE AVAILABLE ON REQUEST