[Qualities of life and happiness].

The phrase 'quality of life' is actually misleading. The designation suggests that the issue has to do with 1 quality, whereas in fact more qualities of life are indicated. Four of these qualities are: 1. the 'livability' of the surroundings, 2. the 'life-abilities' of the individual, 3. the 'utility of life' and 4. the subjective 'satisfaction' with a person's own life. The various qualities cannot meaningfully be collected together in an index. The most comprehensive measure of quality of life is how long and happily a person lives. The relationship between that and oral health has still hardly been studied.