Philosophiae Doctor - PhD / Rehabilitation of edentulous jaws without the option of osseointegrating implants will remain the only treatment option within reach of many older patients for the foreseeable future. Many routine prosthodontic procedures are based on dogmas, because no high-level scientific evidence exists to either accept or reject them, among these is the “neutral zone” (NZ) concept. In spite of paucity of evidence using approved patient-based outcome instruments, it is generally agreed that the NZ should be respected when constructing complete dentures. The purpose of this research project was to determine how shapes of conventional and NZ mandibular dentures differ, and if the two different types of dentures impact differently on oral health–related quality of life by using an accepted oral health-related quality of life instrument as a patient-based outcome. Thirty nine edentulous patients were selected for his prospective, randomised, cross-over, single-blinded clinical trial. Two sets of complete dentures were made for each patient. One denture set was made following conventional biometric guidelines for determining the position of the mandibular posterior denture teeth in relation to the ridge; another set was made following a functional impression of the potential denture space. Each set of dentures was worn for at least two months. A similar number of types of dentures were delivered first. Widths of residual ridges and mandibular denture arches were measured using digital measuring software. Position of denture teeth was related to the ridge. Denture dimensions were compared by means of analysis of variance using the mixed procedure. Using formula of parabola, arch-widths were compared using paired t-tests. Pre- and post-treatment patient feedback was obtained by means of the 20-item Oral Health Impact Profile (OHIP-20) and a preference score. Treatment effect size (ES) was established based on the OHIP-20 scores. Relevant associations among denture dimensions, OHIP-20 scores, preference, age, gender, marital status, education, income, period of edentulousness, and quality of denture-bearing tissue were done using the generalised linear model and correlation analysis. For all statistical analysis, level of significance was determined at p<0.05. The mean age of the sample was 62.3 years. Twenty four patients were female. Mean period of edentulousness was 31 years and mean number of denture sets worn prior to the trial was 2.5. Except for the canine region, NZ dentures were statistically wider than anatomic dentures. The difference in mean widths between the two types of dentures was larger for female patients. Older patients had smaller differences in denture dimensions. More unfavourable denture-bearing tissue was associated with a larger difference in the two types of dentures. Both types of mandibular dentures significantly improved the OHRQoL of patients. Both types of dentures had a high treatment ES. The OHIP-20 instrument could not distinguish a statistical difference in impact on OHRQoL between the two treatment options. There was a minute difference in treatment ES between the two types of treatment. The only domain representing a small clinical benefit between NZ and anatomic dentures was “physical pain”, with the NZ dentures scoring better. There was no correlation between pre- and post-treatment scores for both types of dentures. No significant associations were found between post-treatment OHIP- 20 scores on the one hand and tissue scores, gender, age, education, marital status, period of edentulousness and denture dimension differences on the other hand. Based on OHIP-20 scores, there was a significant association between denture preference and NZ dentures, but not for the other preferences. No significant associations were found between denture preferences on the one hand and tissue scores, gender, age, period of edentulousness and denture dimension differences on the other hand. Even though no significant relationship was found between preference and gender, the majority of female patients preferred the NZ denture and the majority of male patients did not express a preference.Providing new complete dentures improved OHRQoL of edentulous patients. The majority of female patients preferred the NZ compared over the ANA denture. The NZ technique appeared to have a higher positive impact on OHRQoL of female patients compared to male patients.

The aim of this thesis is to describe the development of oral health and possible associations with socioeconomic and socio-behavioural factors, in an adult population over a period of 30 years. A further aim is to describe attitudes to, and demands of dental care, and the impact of oral conditions on quality of life. The study sample consisted of 787-1158 individuals, aged between 35-85 years, randomly selected from Dalarna’s population register in 1982, 2002, 2007 and 2012. The studies were carried out in 1983, 2003, 2008 and 2013, and the participants responded to a questionnaire and a clinical examination of oral status. There has been a substantial improvement in oral status in regard to the mean number of teeth, intact teeth, and less removable dentures over this period of 30 years. The proportion of individuals with alveolar bone loss decreased significantly between 1983 and 2008, but increased significantly between 2008 and 2013. Smoking was the overall strongest factor associated with alveolar bone loss, after adjustment for socioeconomic and socio-behaviour factors, age and number of teeth. Calculus, visible on radiographs, increased significantly between 2003 and 2013. The proportion of individuals with manifest caries declined significantly between 1983 and 2008, but seems to level out between 2008 and 2013. Socioeconomic and socio-behaviour factors were significantly associated with manifest caries. Preventive treatment, meeting the same caregiver as on previous visits, and information about treatment cost was reported to a significantly lower degree as important in 2013, compared with 2003 and 2008, and booking time for treatment was reported as more difficult in 2013, compared with earlier years. Regular recalls was reported as less important in 2013, compared with 2008. A third of the respondents reported oral impact on daily performance and irregular dental visits, limited economy for dental care, less than 20 remaining teeth, manifest caries and temporomandibular disorder were significantly associated with oral impact on daily performance.

Abstract The most common mental disorder, depression, is internationally acknowledged as a considerable public health problem, major depression being one of the leading causes of premature mortality and disability in the world (Murray &amp; Lopez 1996). Besides its associations with disturbances in psychological and social functioning, depression is also associated with various biological alterations. Accordingly, extensive research has been conducted to link depression with several somatic diseases. The relationship between depression and oral health is still obscure, however. This study was carried out to investigate the relationship of depressive symptoms with oral health and related factors in 55-year-old inhabitants of Oulu, 780 of whom participated. Depressive symptoms were measured with the Zung Self-Rating Depression Scale (ZSDS). A high rate of depressive symptoms was associated with symptoms of temporomandibular disorders (TMD), the subjective sensation of dry mouth, and high counts of salivary lactobacilli. An uncertain association was demonstrated between depressive symptoms and abundant growth of salivary mutans streptococci and the presence of yeasts in saliva. Depressive symptoms were associated with edentulousness in a subgroup of men who had never smoked. The dentate women with high rates of depressive symptoms did not consider it equally important to preserve their natural teeth as did the dentate women with fewer depressive symptoms. They also consumed sweets, snacks, and soft drinks more often, and a longer time had elapsed since their last visit to a dentist. No associations between depressive symptoms and periodontal pocketing or dental caries could be demonstrated in this cross-sectional study. It is suggested that depression should be considered as a possible underlying factor when treating patients with TMD symptoms and complaints of oral dryness. Furthermore, considering the discovered association between depressive symptoms and microbial growth, the possibility of an increased risk for impaired oral health among depressed persons is emphasized.