Reports & Studies

Determining patients’ caries risk – what makes sense?

PD Dr. Kristina Bertl, PhD MSc MBA

The main diseases we are confronted with in dentistry are caries and periodontal conditions. Although the results of the fifth German Oral Health Study show a positive trend for the two diseases, effective prevention of both must nonetheless be our primary goal. We discussed the options for caries prophylaxis in a previous article (‘Update on caries prophylaxis’). The current article is intended to provide an overview of the tests for determining patients’ caries risk.

The idea of tests for determining our patients' caries risk is to identify at-risk patients as early as possible and to take countermeasures such as more frequent recalls and/or appropriate caries prevention measures. Most tests for determining the risk of caries are saliva tests. An advantage of this method is that saliva can be taken very easily and in a non-invasive manner.

Saliva tests for determining the risk of caries are broadly divided into ‘non-bacterial’ and ‘bacterial’ tests. In ‘non-bacterial’ saliva tests, it is possible to determine the flow rate and buffer capacity of the saliva, for example. Here, a low flow rate and low buffer capacity are risks for developing caries. In ‘bacterial’ saliva tests, the presence of highly cariogenic bacteria is measured. These bacteria are predominantly Streptococcus mutans and lactobacilli (see also: ‘Streptococcus mutans – the caries pathogen!’). Here, in contrast, a large number of these highly cariogenic bacteria constitutes a risk.

These tests allow us to more precisely estimate the risk of caries, but they should not be used as the sole risk-determination measure, because they are of limited significance without the assessment of additional clinical parameters. A combination of several factors should therefore be taken into account when assessing an individual's risk of caries:

  • Caries history and active initial lesions
  • Poor oral hygiene and high rate of new plaque formation
  • High consumption of sticky and sugary foods
  • Low fluoride intake
  • Low saliva flow rate
  • Low buffer capacity
  • High rate of Streptococcus mutans
  • High rate of lactobacilli

Although the final four points in this list can be determined by caries risk tests, they should always be considered in conjunction with the other factors.


  1. Hennings J. Aktuelle mikrobiologische Methoden zur Bestimmung des Kariesrisikos. ZWR – Das Deutsche Zahnärzteblatt 2019; 128: 20–24