Minimal intervention dentistry and older patients part 1: risk assessment and caries prevention

Population ageing

In many countries the proportion of people aged 65 years and older is growing faster than any other age group as a result of both longer life expectancy and declining fertility rates. In the UK, there are currently three million people aged more than 80 years. This is projected to almost double by 2030 and to reach eight million by 2050. One-in-six of the UK population is currently aged 65 and over, and current trends in ageing suggest that this ratio will increase to one-in-four by 2050.1 While population ageing can be seen as a success story for public health policies and for socio-economic development, it also challenges society to adapt in order to maximize the quality of life for this expanding population. The World Health Organization's document on Global Health and Ageing2 highlights some of the effects of increasing life expectancy, in particular the rise of chronic and degenerative diseases such as heart disease, stroke and diabetes. There has also been an increase in the number of people with one of the most daunting consequences of ever-longer life expectancies, dementia. There is mounting evidence from cross-national data and from studies such as the English Longitudinal Study of Ageing (ELSA)3 that, with appropriate policies and programmes, people can remain healthy and independent well into old age and can continue to contribute to their communities and families. Our challenge in the area of dentistry is to direct resources appropriately to provide effective caries preventive measures to this ever expanding group and those who will join it in the years to come.

Individual ageing

We are all more aware than ever that ageing is a variable process which affects individuals differently. What was once termed the older population has now been sub-divided into the young old (60 to 69 years), the middle old (70 to 79 years), and the very old (80 years and older). Even within these strata of chronological age there is huge variability in the biological and psychological state between individuals. Some people may cope and adapt to ageing in a positive manner while others may view it negatively. In addition, levels of physical infirmity will vary from one person to another within the same age group. Age itself should not be a barrier to any form of dental treatment, rather the individual's needs and demands, along with his/her ability to undergo treatment, should determine the most appropriate level of intervention.

The impact of ageing on oral and dental health

In dentistry, this ageing trend is compounded by a concomitant reduction in levels of edentulism among older adults.4 The UK Adult Dental Health Survey (2009) shows a continuing decline in the percentage of people with no teeth. The proportion of adults who have lost all their natural teeth has decreased from 30% in 1978 to 6% in 2009. Those aged 55 years and over had an average of 1.8 more teeth in 1998 than in 1988.4 Therefore, in the future there will be both greater numbers of older people and increased retention of more natural teeth into old age. The older generation of today are better educated, and have easily accessible sources of information. They are less willing to accept the extraction of teeth and replacement dentures as the only treatment option available to them.5 However, maintenance of the dentition can be challenging for the patient and his/her dental practitioner owing to a variety of factors (Table 1).

The older patient often presents a complex restorative challenge in the dental setting. The provision of treatment can be difficult due to the longer survival of individuals, with chronic medical conditions leading to physical infirmity and, often, negative effects on the oral cavity by associated medications. Furthermore, communication between professional and patient can be affected by hearing difficulties. The older, now partially dentate generation, will present with a variety of oral conditions that reflect a lifetime's exposure to adverse activities and pathological influences. The dental diseases to which the older generation are particularly prone may include root caries, wear, periodontal disease, edentulous spaces, poor quality alveolar ridges, ill-fitting dentures, failing fixed prostheses, mucosal lesions, oral ulceration, xerostomia and oral cancers.6

The relatively high disease burden that may be presented by older patients, in combination with the complexity of challenges inherent in providing dental treatment to this group, makes it critical that dentists assess not only their dental requirements but also see the patient as a person. They should encompass their socio-economic status, medical condition, physical and functional capabilities, cognitive status, dental history and realistic oral hygiene expectations (Figures 1 and 2). Dental practitioners should also assess wider issues such as social and familial support, transportation needs, fear and anxiety issues, consent and perceived need for treatment.7

Minimal intervention dentistry (MID)

The concept of minimal intervention dentistry has evolved with an increased understanding of the caries process and the development of adhesive restorative materials.8 It is recognized that early carious lesions confined to enamel can be reversed and that the ‘extension for prevention’ approach is no longer appropriate in modern dentistry. The key principle of minimal intervention dentistry is early disease control and the avoidance of surgical intervention until it is absolutely essential.9

To implement this ‘medical model’ of dentistry, every patient should undergo risk assessment for dental disease. This allows for the early detection and control of active disease processes and should minimize the need for surgical intervention. The patient becomes empowered to improve his/her oral health and, if successful, should require fewer appointments.10

Regular dental attendance for older patients can be complicated by illness, difficulty accessing transport and sometimes by fear of the dental visit. In addition, the limited financial means of many older people may restrict the dental treatment they can afford. MID, if employed correctly, can avoid the need for frequent dental treatment and can be more affordable than operative intervention when disease is established.

Risk assessment

Older people are particularly vulnerable to an increase in caries risk as a result of xerostomia-inducing medications or disabilities that preclude effective plaque removal. Furthermore, with commonly occurring age-related gingival recession, the root surfaces are exposed to the oral environment and become vulnerable to the caries process. Therefore, a patient's risk of dental disease will change as he/she ages and should be routinely assessed. The ‘caries balance’ is determined by the relative weight of the sums of pathological and protective factors.11

There are a number of tools available to the dental practitioner to complete a comprehensive caries risk assessment. A quick, cost-effective and easy tool is a caries risk assessment form (Figure 3). This can form part of the patient's records and can be reviewed periodically to ensure that any changes in disease risk are detected. It can also be useful as an educational tool to demonstrate to elderly patients the factors that are increasing their risk of dental disease. Many of these factors may be beyond the patient's control, such as poor manual dexterity or xerostomia, but infrequent cleaning or frequent sugar intake can be altered in favour of reducing caries risk. This knowledge can empower older patients to make decisions to alter that which is within their control, allowing them to tip the caries balance away from disease progression.

An innovative caries assessment tool is the Cariogram software programme – a computer-based caries risk assessment model.12 This was developed by Bratthall and co-workers at the dental school in Malmö, Sweden. The program's algorithm evaluates caries-risk data and summarizes the results as a pie chart which serves as a useful educational tool for the clinician when discussing caries risk with the patient13 (Figure 4). The software is available to download free of charge for educational purposes or for other non-commercial activities from the Malmö university website; http://www.mah.se/english. The Cariogram is best used in conjunction with chairside tests that measure stimulated saliva rate, salivary pH and the numbers of Streptococcus mutans and Lactobacillus species in saliva (Figure 5).

In 2001, Banting suggested that a powerful, predictive tool for root caries would result from the combination of risk assessment measures and a valid diagnostic test.14 From the limited data available to date on diagnostic tests for root caries, tests determining the presence or absence of Streptococci mutans and Lactobacilli appear to be the most clinically valid.14 The prevention of dental disease could be optimized if high-risk individuals were identified as it is known that about one third of the older adult population bears most of the root caries burden.15

Prevention

Once a patient has been risk assessed, an appropriate caries prevention programme can be implemented. Caries prevention measures can be home-based or surgery-based and should be tailored to the individual's needs. As mentioned previously, elderly patients may have difficulty accessing transport and may have a preference for a home-based approach. Others may struggle to maintain effective plaque control as a result of poor manual dexterity or impaired memory and a surgery-based intervention combined with a home-based regime would be appropriate. Oral hygiene instruction and dietary advice should be given, based on information gained during the risk assessment process. Any advice given should also be provided in written format that the patient can refer to at home or give to a relative or carer to read. It is advisable to use a large font and to limit advice to a few key messages to improve compliance.

Prescription only toothpastes, containing 2800 and 5000 ppm fluoride, provide the dental profession with easy to use, suitable interventions for high caries risk elderly patients. These products have been shown to be more effective than toothpastes with lower fluoride concentrations at both preventing new carious lesions and at arresting existing carious lesions on root surfaces.16^,17 This intervention is easily incorporated into the patient's daily oral hygiene routine.

Evidence to date has highlighted a several-fold increase in tooth remineralization through the additive effects of fluoride, calcium and phosphate.18 One method for stabilizing calcium and phosphate ions is through the application of casein phosphopeptides (CPPs), which stabilize nanoclusters of amorphous calcium phosphate (ACP) in supersaturated solution. CPP–ACP has been commercially developed as Recaldent ^TM which is sold for professional use as Tooth Mousse (10% CPP–ACP) (GC Dental, Newport Pagnell, Buckinghamshire) or as MI Paste Plus (in combination with 900 ppm fluoride).

Prior to application, it is essential to question all potential users of Recaldent ^TM products regarding possible IgE-mediated casein allergies (by posing the question ‘Do you ever have any allergic reactions when you drink milk?’). However, older patients with lactose intolerance can use Recaldent ^TM products, as they do not contain lactose.

Older adults are more susceptible to faster plaque production than younger adults because of the dual effects of gingival recession and reduced salivary effectiveness.7 Since the work of Loë et al in 1970,19 a succession of studies have proven the efficacy of chlorhexidine 0.2% mouthwash in plaque inhibition. Chlorhexidine mouthwash is used in hospitals and nursing homes throughout the world to aid oral hygiene and, despite the potential for staining, is a very useful adjunct in elderly patients who have difficulty in maintaining adequate plaque control through brushing alone.

Where there is evidence of xerostomia, a variety of topical agents are now available to help reduce caries risk and improve oral comfort. One such example is the Biotene ^TM system which includes mouthwashes, gels and toothpastes containing bioactive enzymes designed to protect teeth and soft tissues. It is essential to advise patients with xerostomia to avoid using fizzy drinks or sweet acidic sweets to alleviate their dry mouth and instead to direct them to an alternative such as sugar-free chewing gum. While many of these patients will be aware of the role of sugar in dental disease, the dangers of acid erosion may be less well known among this group.

For older patients with a high caries rate or poor compliance with oral hygiene instruction, there are a number of surgery-based interventions available to reduce caries risk. The incorporation of chlorhexidine, fluoride and sodium diamine fluoride (SDF) varnishes in the control of dental caries in older patients is a relatively recent development (Figure 6). All of these preparations have been shown to be effective at reducing the risk of future root caries in randomized controlled clinical trials.20^,21^,22^,23

Chlorhexidine varnish, sodium fluoride varnish and SDF solution have their respective disadvantages. The most commonly encountered side-effects of chlorhexidine varnish are staining of teeth and an unpalatable, bitter, taste. The inherent disadvantage of using SDF solution is that, after it is applied to caries lesions, the lesion will be stained black. However, despite the potential problems, these caries-preventive strategies seem to be acceptable to the elderly.20 Applying varnishes is simple, quick and non-invasive and can be used in a domiciliary setting. Furthermore, it reduces dependence on patient compliance for success, and treatment can be provided by a dental hygienist or therapist.

Fissure sealants can also form part of a caries prevention programme as they help to modify local factors that affect the onset and progress of caries. Resin-based fissure sealants are commonly placed in young patients and may be equally effective in older adults. Where isolation may not be possible, glass ionomer cement-based fissure sealants can be used to bond chemically to tooth surfaces which have been conditioned with 10% polyacrylic acid. These fissure sealants are more soluble and susceptible to acid dissolution than resin-based sealants but do leach fluoride ions, which may provide a cariostatic effect.

Recall

The MID approach should reduce the number of dental visits required by older patients. However, it is important to recall high caries risk patients frequently unless their risk decreases.

Conclusion

The caries balance may shift unfavourably as an individual ages; regular risk assessment allows the dental practitioner to identify this shift at the earliest possible opportunity. Caries prevention plans and recall length can be tailored and adjusted to reflect the individual's risk of future caries progression and can tip the balance back in favour of optimal future dental health. Risk assessment and caries preventive measures highlight high-risk habits to older patients and empowers them to reduce their own need for operative dental treatment. The older patient can be equipped with better knowledge and cleaning aides to overcome difficulties that he/she may encounter in maintaining good oral hygiene.