What is the role of diet in the prevention of dental diseases?
This summary is based on information found in Comprehensive Preventive Dentistry (Wiley Publishing, 2013)
- Dental diseases in which diet plays an etiological role include enamel developmental defects, dental caries, tooth wear, and periodontal disease.
- The main cause of tooth loss is dental caries, and in adults the main cause of tooth loss is periodontal disease.
- There is strong evidence from epidemiological studies for an association between the amount and frequency of free sugars intake and dental caries.
- Studies of human populations show that diets that are rich in complex carbohydrates from starchy staple foods and diets that are high in fresh fruit are associated with low levels of dental caries.
- The term ‘sugars’ refers to all mono- and disaccharides; the term ‘sugar’ only refers to sucrose;
- the term ‘free sugars’ refers to all mono- and disaccharides added to foods by the manufacturer, cook, or consumer, plus sugars naturally present in honey, fruit juices, and syrups; and
- the term ‘fermentable carbohydrate’ refers to free sugars, glucose polymers, fermentable oligosaccharides, and highly refined starches.
The impact of dental diseases on well being
- Dental disease is associated with a low mortality; however, dental disease impacts self esteem, social integration into society, and the ability to speak and eat.
- Dental caries and periodontal disease result in tooth loss, which reduces enjoyment of eating and the confidence to socialize and in some vulnerable groups such as the very old, is associated with increased risk of under nutrition (Lamy et al. 1999; Dion et al. 2007; De marchi et al. 2008).
- The systemic effect of nutrition on the teeth
- Nutritional status affects the teeth during the preeruptive stage. Deficiencies of vitamin D, vitamin A, and protein energy malnutrition (PEM) have been associated with enamel hypoplasia.
- Nutrient deficiencies including protein deficiency and vitamin A deficiency are associated with salivary gland atrophy, which will reduce saliva flow and may impact the buffering capacity of saliva, which will reduce the ability of saliva to neutralize plaque acids.
- Malnutrition may therefore increase the susceptibility to dental caries when sugars are available in the diet.
- The main overriding factor in the etiology of periodontal disease is the presence of plaque, and prevention measures focus on oral hygiene.
- A high sucrose intake is associated with increased plaque volume due to the production of extracellular glucans.
- Higher plaque volumes and increased gingivitis with high sucrose diets compared with low sucrose diets (Scheinen et al. 1976; Sidi and Ashley 1984).
- With an increased understanding of the disease at the cellular level coupled with improved means of assessing nutritional status, emerging evidence suggests a significant role of diet in the etiology of periodontitis and strong associations between systemic inflammatory diet-related conditions and periodontal disease.
- The important roles of vitamin C in the tissues of the periodontium are well established. Recent studies support an association between low serum vitamin C status and periodontitis.
- Vitamin C plays an important role in collagen formation and the structural integrity of the periodontal ligament, blood vessel walls, and its role in the formation of the alveolar bone matrix.
- Diet plays a key role in the etiology of obesity and of diabetes, and both of these conditions are associated with increased risk of periodontitis.
- Lifestyle interventions to address being overweight and obesity may also positively impact periodontal health.
The intraoral effect of diet on the teeth
Teeth are most susceptible to dental caries soon after they erupt; therefore, the peak ages for dental caries are 2–5 years for the deciduous dentition and early adolescence for the permanent dentition.
Which is more important—frequency of sugars consumption or the amount of sugars consumed?
- The evidence discussed so far clearly shows an association between total amount of sugars consumed and dental caries. However, the two variables are highly correlated so that when the frequency of consumption increases so does the total amount consumed (World Health Organization 1990). Likewise, a reduction in frequency in intake of sugars should result in a reduction in the total amount of sugars consumed.
- Human epidemiological studies have also indicated that the frequency of sugars intake is associated with development of dental caries (Holbrook et al. 1989; Holbrook et al. 1995).
- The findings of human epidemiological studies suggest that sugars intake should be limited to no more than 4 intakes per day.
Does the cariogenicity of different types of sugar differ?
- All mono- and disaccharides are cariogenic, and some evidence suggests that sucrose in particular is cariogenic.
- Clinical studies show that glucan formation increases the porosity of plaque, which permits deeper penetration of dietary sugars and increased acid production adjacent to the tooth surface (Zero 2004).
Does reducing sugars intake remain important when a population is exposed to fluoride?
- More than 800 controlled trials of the effect of fluoride on dental caries have been conducted and show that fluoride is the most effective preventive agent against caries (Murray 1986).
- More recent studies of the relationship between sugars and dental caries are confounded by the presence of fluoride but show that a relationship between sugars intake and caries still exists in the presence of fluoride.
- A review of the changes in the prevalence of dental caries concluded that, even when preventive measures such as use of fluoride are employed, a relationship between sugars intake and caries still exists and that sugars continue to be the main threat to dental health despite progress made using fluorides (Marthaler 1990).
Does starch cause dental caries?
- Populations that consume a high-starch diet low in sugars have low caries experience compared with populations who consume diets relatively low in starch but high in sugars.
- Overall the evidence shows that staple starchy foods such as rice, potatoes, and bread are of low cariogenicity.
- Highly refined and heat-treated starch can cause dental caries but less so than sugars. Foods containing cooked starch and substantial amounts of sucrose appear to be as cariogenic as similar quantities of sucrose.
Does fruit cause dental caries?
- There is little evidence to show that fruit consumption is an important factor in the development of dental caries when consumed as part of the mixed human diet.
- Theoretically dried fruit may potentially be more cariogenic since the drying process breaks down the cellular structure of the fruit, releasing free sugars.
- However, research has shown that dried fruits contain many factors that protect against decay in addition to being a good source of dietary fiber and micronutrients making them a valuable contribution to fruit intake.