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Whiplash trauma, a hyperextension-flexion trauma to the neck that is often related to a car accident, affects tens of thousands in Sweden every year. A significant proportion will develop long-term symptoms including neck pain and dysfunction – this is embraced as Whiplash associated disorders (WAD). Some individuals also develop pain and dysfunction in the orofacial region that is denoted as Temporomandibular disorder (TMD). TMD is common in the population with a prevalence of about 10% but the relation to whiplash trauma is still unclear. The limited number of prospective studies on TMD after whiplash trauma show diverging results, but it has been suggested that TMD develops over time and not in close proximity to the trauma. Prospective studies are needed to determine the course of jaw pain and disability after whiplash trauma.

The general aim of this thesis was to evaluate the presence and course of pain and disability in the jaw and neck regions at the acute and chronic stages after whiplash trauma.

This prospective cohort study included at baseline 176 cases with a recent whiplash trauma, and 116 age and gender matched controls without a history of neck trauma that were recruited from the general population. The cases had visited the emergency department at Umeå university hospital, Sweden, with neck pain within 72 hours following a car accident and had been diagnosed with neck distortion by a physician. The cases were examined within one month after the trauma (December 2010 to January 2016) and at a 2-year followup (December 2012 to January 2018). All participants completed questionnaires regarding pain and disability in the jaw and neck regions, physical symptoms (pain and non-pain items), and depression. At baseline, 80 of the cases and 80 of the controls also completed a 5-minute chewing capacity test. At the 2- year follow-up, 119 cases (68%) and 104 controls (90%) were re-examined with the same questionnaires.

Compared to controls, within one month after a whiplash trauma cases reported significantly more pain in the jaw and neck regions with a positive correlation between the intensity of pain in these regions (Paper I). In the acute stage after trauma, cases, compared to controls, showed a reduced chewing capacity, and this was related to the severity of neck disability (Paper II). For cases, jaw and neck pain correlated positively to each other, to non-specific physical symptoms, and to depression at both the acute (Paper III) and chronic stages (Paper IV). About one third (34%) of the cases reported orofacial pain at baseline, and for a majority of these, the pain persisted at the 2-year follow-up (Paper IV).

The presence of orofacial pain early after a whiplash trauma indicates involvement of central sensitization and spread of pain between the jaw and neck regions. The positive correlations between pain in the jaw and neck regions, and to psychosocial factors, underline the integration of these regions and the importance of a biopsychosocial perspective. The impaired jaw function shortly after a neck trauma further underlines the close sensorimotor relationship between the trigeminal and cervical regions. The finding that orofacial pain is common shortly after whiplash trauma, and often persists into the chronic stage, indicates that assessment in the acute stage should include both the neck and jaw regions. From this, it follows that multidisciplinary teams that entail both medical professions and dentists specialised in orofacial pain can be beneficial in the early assessment after whiplash trauma.