Risk refers to the probability that an event will occur within a certain timeframe. In dental epidemiology, risk refers to the probability that an individual will contract an oral complication or disease at a certain age or age span due to exposure to certain conditions or factors. Characteristics of risk include exposure and risk ratio. Risk factors refer to aspects of behavior, heredity, or environment that alter the probability of the occurrence of a disease (Burt, 2005). Examples of risk in dental epidemiology include tobacco use, harmful use of alcohol, unhealthy diet, and poor oral hygiene. These factors increase the probability that an individual will contract an oral disease if he/she is exposed to them. Risk ratio refers to the comparison of the probability of a disease occurring between two groups. The ratio is computed by dividing the risk encountered by people in group A with the risk encountered by people in group B (Timmreck, 2002). Factors used to divide people into groups when calculating risk ratio include sex and exposure to a certain risk factor.
Association refers to the statistical relationship between two events, variables, outcomes, or characteristics such as a risk factor and the prevalence of a disease (Wakeford & McElvenny, 2007). Types of the association include spurious association, indirect association, and direct association. Examples of measures of the association include risk ratio, rates ratio, odds ratio, and proportionate mortality ratio. Rate ratio is a comparison of incidence, person-time, and mortality rates of individuals in two groups that are separated by demographic characteristics such as sex and age (Timmreck, 2002). Characteristics of the association include dose-response relationship, consistency, time sequence, biological plausibility, and specificity (Burt, 2005). Specificity aims to establish whether exposure to a certain risk factor causes disease and whether the exposure occurs before the disease or not (Wakeford & McElvenny, 2007). The findings of such a study must be validated by other studies conducted in different populations in order to determine its consistency. Intense or more exposure of an individual to a risk factor should be associated with higher rates of the disease. Finally, the association must have biological credibility (Timmreck, 2002). In that regard, a plausible mechanism of how exposure causes the disease should be supplied. An example of an association in dental epidemiology is the relationship between long-duration breastfeeding (24 months or beyond) and dental carry.
Causation is an epidemiological concept that explains the occurrence of an event or outcome (Scheutz & Poulsen, 1999). For instance, if agent A leads to the development of a disease, then agent A is the cause of the disease. The main characteristics of a cause include positivity or negativity, existence as a host or environmental factor, and existence before the effect (Wakeford & McElvenny, 2007). A cause must precede the effect in order to be described as biologically plausible (Scheutz & Poulsen, 1999). In addition, it should exist as either a host or environmental factor. Examples of environmental factors include events, social or economic phenomena, lifestyle habits, and conditions. Finally, the cause can either be defined by the presence of a causative exposure or the absence of a preventive exposure (Timmreck, 2002). The criteria used to determine causation are based on factors that include the strength of the association between cause and outcome, consistency, specificity, temporality, experiment, coherence, and analogy (Timmreck, 2002). An example of causation in dental epidemiology is the relationship between tooth decay and the consumption of sugary foods coupled with poor oral hygiene.
References
Burt, B. A. (2005). Concepts of Risk in Dental Public Health. Community Dentistry and Oral Epidemiology 33(4), 240-247.
Scheutz, F., & Poulsen, S. (1999). Determining Causation in Epidemiology. Community Dentistry and Oral Epidemiology 27(3), 161-170.
Timmreck, T. C. (2002). Introduction to Epidemiology. New York, NY: Jones & Bartlett Learning.
Wakeford, R., & McElvenny, D. (2007). From Epidemiological Association to Causation. Occupational Medicine 5(7), 464-465.