A conceptual model of oro-facial health with an emphasis on function.

The individual inclination to lead an autonomous life until death is associated with requirements that may be of physiological, psychosocial and environmental nature. We aim to describe a conceptual oro-facial health model with an emphasis on oro-facial function, taking the domains of quality of life and patient-centred values into account. In the context of oro-facial function, the requirements of life are met when the oro-facial system is in a fit state. 'Fitness of the oro-facial system, that is oro-facial health, is a state that is characterised by an absence of, or positive coping with physical disease, mental disease, pain and negative environmental and social factors. It will allow natural oro-facial functions such as sensing, tasting, touching, biting, chewing, swallowing, speaking, yawning, kissing and facial expression'. In the presented conceptual model of oro-facial health, it is postulated that each individual has present and future potentials related to biological prerequisites and resources that are developed by an individual through the course of life. These potentials form the oro-facial functional capacity. When the individual potentials together do not meet the requirements of life anymore, dysfunction and disease result. The oro-facial system is subject to physiological ageing processes, which will inevitably lead to a decrease in the oro-facial functional capacity. Furthermore, comorbid medical conditions might hamper oro-facial function and, alongside with the ageing process, may lead to a state of oral hypofunction. Currently, there is a lack of widespread, validated, easy-to-use instruments that help to distinguish between states of oro-facial fitness as opposed to oral hypofunction. Clearly, research is needed to establish adequate, validated instruments alongside with functional rehabilitation procedures.