Phobia for dental treatment often has a considerable influence on a person’s perceived quality of life. In this research project, the relationship and interactions between dental anxiety, oral health and quality of life were studied. Scores on the basis of several parameters of these factors were analyzed prior to and following dental treatment. It appeared that quality of life was asso ciated with both dental anxiety and oral health. When improvement in quality of life was investigated, it appeared that this was only statistically correlated with a reduction in dental anxiety. These findings suggest that treatment of dental phobia patients should focus not only on making patients treatable (pharmacologically), but also on reducing anxiety.

The impact of oral health on quality of life among orthodontic patients was assessed using the Child Oral Health Impact Profile. Responses of parents and children to questions about the quality of life of the child were very similar, suggesting that the parents were quite well able to assess the oral health-related quality of life of their children. Girls experienced more adverse effects on their quality of life due to oral health problems as compared to boys. Subscales of the Child Oral Health Impact Profile appeared to have little predictive value with respect to the general feeling of healthiness among orthodontic patients.

Children with a serious congenital craniofacial disorder experience a variety of problems. Research on quality of life in these children has commenced relatively late. A specially developed questionnaire, the Child Oral Health Impact Profile, was used for a group of cleft lip and palate children and their parents. The study set out to determine the extent to which the answers given by the children corresponded to those of their parents. The children’s perception of oral health-related quality of life appeared to differ from that of their parents.

In order to gain insight into the degree to which periodontal disease is related to quality of life, research was carried out among 85 patients with moderate or severe periodontal disease in which they were asked to complete the Oral Health Impact Profile-NL49. Their scores on this questionnaire were compared with the scores of 85 control subjects of comparable age and gender. The patients with periodontal disease demonstrated significantly worse scores compared to the control group and patients with severe periodontal disease had scores which were statistically significantly worse than patients with moderate periodontal disease. The results of this study suggest a causal negative association of periodontal disease with quality of life.

Accidental detection of an asymptomatic apical periodontitis raises the question whether this lesion should be treated or not. Arguments favouring treatment are that the inflammation may cause pain in the future, may enlarge or may negatively affect the host’s resistance. Reasons for not treating may be that treatment weakens the tooth, may cause iatrogenic damage and that treatment is expensive and burdensome for the patient and does not lead in all cases to complete healing. Scientific evidence supporting either choice, whether treating the lesion or not, is lacking. In making such decisions, therefore, personal judgments by the patient and the dentist concerning the impact on the quality of life of the patient play an important role.

Tooth loss leads, depending on the number and location of missing teeth, to a certain degree of loss of function. This loss of function might lead to an impairment of oral health-related quality of life. The literature provides fairly strong evidence that tooth loss is associated with impaired oral healthrelated quality of life. The locations where teeth are missing and the distribution in the tooth arch of the teeth that still remain have an effect on the degree to which oral health-related quality of life is impaired. These findings are independent of the context and the measurement instrument used. With respect to tooth replacement no direct evidence exists concerning which type of replacement for which cases of tooth reduction have the largest positive effect. Research in this area is still in its infancy.

In clinical decision-making on whether or not to treat an oral disease and on making a choice from the spectrum of treatment options, the influence of the treatment on the physical and psycho-social well-being of the patient should play a crucial role. This awareness originates from gerodontology. To assess the value of a potential treatment, the concept quality of life has been advanced and various related questionnaires have been developed and employed. In the meantime, doubts have arisen about the value of these questionnaires. The present-day trend is to return to so-called qualitative research, which consists of systematic interviews of groups of older people using open-ended questions without making use of structured response options.

In this study, the impact of oral health on the daily functioning of a group of individuals addicted to alcohol and/or drugs that were being treated at a centre for specialized dentistry in Amsterdam was investigated. Every new patient who reported to the clinic received the OHIP-14-questionnaire at home by post with the request that it be filled in and returned. A total of 110 usable questionnaires were returned (response 27.5%). The average OHIP-score (40.6;  standard deviation 12.9) can be termed substantial when compared to other patient groups. On the subcategories ‘physical pain’, ‘psychological discomfort’ and ‘psychological disability’, the patients scored highest, and on the subcategory ‘functional limitations’ the lowest. The poor oral health of the patient group studied has a substantial impact on daily functioning. These baseline results will be used for measuring the effect of dental health treatment at this centre for specialized dentisty.