Occlusal characteristics, temporomandibular disorders, and oral health-related quality of life in the Northern Finland Birth Cohort 1966.

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Auditorium F202

Topic of the dissertation

Occlusal characteristics, temporomandibular disorders, and oral health-related quality of life in the Northern Finland Birth Cohort 1966.

Doctoral candidate

DDS Elisa Tervahauta

Faculty and unit

University of Oulu Graduate School, Faculty of Medicine, Research Unit of Population Health

Subject of study



Professor Ambrosina Michelotti, University of Naples Federico II, Italy


Professor Emeritus Pertti Pirttiniemi, University of Oulu

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Occlusion, temporomandibular disorders (TMD), and oral health-related quality of life among Finnish adults.

Malocclusions are a set of different deviations from normal occlusion. Temporomandibular disorders (TMD) on the other hand, includes pain conditions and dysfunctions of the temporomandibular joints, masticatory muscles, and related tissues. Malocclusions and TMD are very common in the modern population, so the treatment of these problems also incurs considerable costs for society. In addition, malocclusions and TMD have been found to have a negative effect on an individual's oral health-related quality of life (OHRQoL), including physical, psychological, and social well-being. However, the association between malocclusions and TMD is still in debate.

The aim of this study was to examine occlusal characteristics, their association with dental arch widths and TMD, and further investigate the association between TMD and OHRQoL. The study population, consisting of 1,964 people, was part of the volunteers who participated in the Northern Finland Birth Cohort 1966 (NFBC1966) study. In the 46-year follow-up study, a clinical examination of oral health was performed, and 3D dental models from the dentition were taken, from which occlusal features were determined. Participants also completed standardized questionnaires including questions on TMD and OHRQoL.

The present study found that the probability of malocclusions increased when the upper dental arch is narrow and tapered-shaped, and most likely occurred together with other malocclusions. In addition, sagittal malocclusions were associated with TMD: malocclusions in the canine area were associated with pain-related TMD, while distal occlusion had a weak association with joint-related TMD. Of these, especially pain-related TMD in females was associated with lower OHRQoL related to psychosocial burden.

Due to the unique material, the results can be generalized to correspond to the middle-aged adult population in Northern Finland. The results of this study may help to improve selection criteria of the patients and thereby the quality, cost-efficiency, and outcome of public dental care. Equitable prioritization requires knowledge of what types of malocclusions or TMD are most likely to cause harm to the individual in order to allocate resources to those who are more likely to benefit from treatment. The findings of this study emphasize the importance of individual treatment planning.
Last updated: 23.1.2024