Interview: ‘6.3 billion people suffer from tooth decay’

Can you provide an update on the problem of dental decay, or caries, today in the world?
Worldwide, dental caries continue to be an endemic infection and a major public health problem. While caries rates decreased during the 20th century in the United States, they were relatively unchanged during the periods 1988-1994 and 1999-2002 based on NHANES surveys. In children 2-11 years of age, this survey found that 41 per cent have caries of the primary dentition, and that 21 per cent of the children had untreated caries when evaluated. Over the age of 20, the survey found that 91 per cent had a ‘coronal caries experience,’ meaning that there was at least one decayed or filled tooth surface.

 

In this same group, root caries experience was found in 18 per cent of the population. It was noted that the prevalence of root caries increased with age and reaches approximately 32 per cent in those aged 60 and older. As more people are retaining their teeth as they get older, root caries is becoming much more common among patient populations, and an increasing concern among dental professionals.

Globally, the changes have been more dramatic. In the developing world, caries continues to be a serious problem among children. The lack of oral hygiene, access to fluoridated water, toothpaste and rinses, coupled with a lack of dental care, come together to cause a serious problem in many countries. Developed countries seem to mimic what has been seen in the United States.

In summary, despite tremendous improvement, 6.3 billion people – or nearly 80 per cent of the world’s population – still suffer from tooth decay (WHO - Report on oral health, 2003). Over the past 20 years, much attention has been placed in understanding why caries continues to be a problem. This interest has established the presence and extent of caries depend on both primary and secondary contributory risk factors.

Can you describe what the contributory risk factors are for caries development?
Development of caries is the result of three independent factors coming together – the causative agent (plaque bacteria), the host and the environment (see Fig. 1: The caries process involves interaction between the tooth as host and cariogenic bacteria as the agent – such as strep mutans and lactobacillus. The environment also contributes in the form of available cariogenic foods, such as fermentable carbohydrates. All of these factors together contribute to the disease state - dental caries). Each of these alone or even two together will not result in caries being developed. All three are necessary. Let’s look at each one briefly.

Plaque bacteria – within the dental plaque, cariogenic bacteria that produce the acid responsible for demineralization exist along with a number of other non-cariogenic bacteria. Streptococcus mutans and lactobacilli the primary bacteria implicated in caries development, while other low-pH bacteria have also been identified in plaque adjacent to early carious lesions and have been implicated in the caries process.

Host – the teeth are made of three mineralized tissues – the dentin, which forms the core of the crown and root of the tooth, the enamel, which is over the coronal dentin and is exposed to the oral cavity, and the cementum, a thin layer of mineralized tissue overlying the root dentin, and is responsible for anchoring the periodontal fibers which hold the tooth in place. These tissues have a natural level of resistance to acid attack, which can be overcome by the acid that is produced by the plaque bacteria. The use of fluoride, discussed later, can increase this acid resistance.

Environment – In order for the plaque bacteria to produce acid and cause the tooth to deminerlize, a carbohydrate source must be present. The plaque bacteria consumer the carbohydrate and produce lactic acid as a byproduct – the lactic acid is secreted into the surrounding environment and can demineralize the tooth. The increase in consumption of sugar containing drinks and snack foods has contributed to the up tick in caries not only in the developed world, but also the developing world, as more countries shift to a ‘western – type’ diet.

In addition to these primary risk factors, a number of other risk factors can also contribute to the development of caries. These include:

• Medication induced xerostomia – reduction of saliva results in a more favorable environment for caries to develop.
• Periodontal disease and treatment – results in the exposure of the root surface and the more susceptible dentin to caries development.
• Restorations – teeth are being kept longer, often with restorations present. Open/defective margins can occur over time, resulting in recurrent decay.
• Orthodontic treatment – inadequate plaque control around brackets can result in white spot (early, reversible) carious lesions.
• Inadequate oral hygiene – this will remain a prominent contributory factor.
• It is important to note that as a person ages, different risk factors may play a greater influence then others. (This is described in Fig. 2: Risk factors do not always affect all age groups the same. As seen in this diagram, some risk factors may have more influence over the development of caries at certain ages. It is important for the dental professional to keep this in mind when conducting a risk assessment.)

How does the use of fluoride help prevent caries development?
During demineralization, the acidogenic bacteria in the plaque produce acid, which causes the pH to drop below 5.5. Under these acidic conditions, the minerals that make up the tooth structure, calcium and phosphate, are lost. This is termed the threshold or critical pH. However, as the pH reverses and starts to increase, mineral migration reverses, resulting in remineralization of the area that previously was demineralized, with uptake of calcium and phosphate present at the tooth surface.

Fluoride, if present, will also enter the tooth to aid remineralization, resulting in the formation of a stronger fluorapatite crystal than the original hydroxyapatite (see Fig. 3: Demineralization occurs when organic acids formed by plaque bacteria cause hydroxyapatite crystals to partially dissolve. During and after acid attacks, the minerals in saliva help the partially dissolved crystals to re-form or remineralize with new hydroxyapatite crystals. Fluoride enhances remineralization — it becomes incorporated into the outer surfaces of the crystals leading to the formation of Fluorapatite — this is less acid soluble than hydroxyapatite and the tooth is more resistant to future acid attacks). Repeated production of acid by plaque bacteria, often due to continuous or frequent consumption of carbohydrates, will eventually result in a net loss of mineralized tissue, whether fluoride is present or not.

Fluoride is a widely used and very successful risk modifier and preventive measure. Fluoride has played an important role in the prevention of dental caries since the introduction of water fluoridation in the 1940s, and is considered to have made an impact on the reduction in caries in regions of the world where fluoridated water, toothpaste and rinses have been available.

How should a dental professional approach caries prevention with his/her patients?
In order to determine appropriate preventive care, a risk assessment is required. Due to the multi-factorial nature of caries development, the dental professional needs to evaluate each potential risk factor and determine what role, if any, it plays in the patient’s caries risk. Fortunately, there are several documented methods of performing risk assessments, ranging from individualized methods to standardized techniques. Standard risk-assessment protocols include the use of Cariogram, CAries Management By Risk Assessment (CAMBRA) and the Caries-risk Assessment Tool (CAT). CAMBRA has received extensive attention – more information can be found in the November 2007 issue of the Journal of the California Dental Association.

Once the risk assessment is performed, the dental professional can then determine what steps are necessary to reduce the risk for caries development. The steps taken can include diet modification, application of in office fluoride, such as fluoride varnish, prescribing take home high concentration fluoride dentifrice, oral hygiene instruction, and the use of anti-bacterial rinses to manage dental plaque build up. Proper education of the patient, coupled with patient motivation and positive reinforcement of good behavior at subsequent dental visits should provide positive results.

Thank you very much for this interview.

 

Attend Dr Fotinos Panagakos’s CE accredited lectures at FDI! 

On 2 and 4 September, 2010, Dr Fotinos Panagakos will offer a 60-minute lecture to a live audience at FDI in Salvador, Brazil.

2 September at 10:30 a.m. – noon local Brazilian time: Tooth Wear and New Technology to Manage Dentin Hypersensitivity

4 September at 10:30 a.m. to noon local Brazilian time: Caries Risk Assessment and Management Through the Use of In Office and Home Fluoride Therapy

Participants will receive one ADA CERP C.E. credit per lecture. Attendance for FDI visitors is FREE. The lectures will be in English, and you will find us at the FDI on the exhibition floor at booth 117-126.

Please register under www.DTStudyClub.com > Online Courses > Symposia at FDI.

 

Please visit the company profile of Colgate-Palmolive Co. for more information.