Data construction patient characteristics

Fig 3 summarises all the variables used in the analysis, including the level of measurement (nominal, ordinal or interval). It also states whether the variable was obtained via the dentist registration form or the patient questionnaire.

Using data from the patient questionnaire, the SES of older people was determined based on their highest level of education (low/average/high) and/or their profession using the ISCO classification [20].

Frailty is often defined on the basis of clinical tests [21–25]. For the sake of feasibility in this study—which is based on data from questionnaires, based on routinely available data and self-administrated data—we chose a simple classification of the ability to carry out ‘Activities of Daily Living’ (ADLs) [26], derived from the known measures of frailty. This was determined as a sum score of seven dichotomous items about mobility, care dependency and care support (Cronbach’s alpha = 0.756). An older person was deemed frail if he or she affirmatively was responded to three or more questions.

Capability for oral health self-care was determined on the basis of whether or not the older person was able to brush their teeth every day and whether or not brushing had become more difficult.

The various wishes of older patients associated with their oral status were recoded into whether or not there was a wish to improve their current oral status.