Is temporomandibular pain in chronic whiplash-associated disorders part of a more widespread pain syndrome?

Whiplash trauma did not predict jaw pain after 2 years: an explorative study

OBJECTIVES

To explore predictive factors for the development and maintenance of jaw pain over a 2-year period.

METHODS

One hundred nineteen cases (73 women) and 104 controls (59 women), mean age 34.9 years (SD 13.9), attended baseline and 2-year follow-up examinations. The whiplash cases visited the emergency department at Umeå University Hospital, Sweden, with neck pain within 72 h following a car accident, and baseline questionnaires were answered within a month after trauma. Controls were recruited via advertising. Inclusion criteria were age 18-70 years, living in Umeå municipality and Swedish speaking. The exclusion criterion was neck fracture for cases and a previous neck trauma for controls. Validated questionnaires recommended in the standardized Research Diagnostic Criteria for temporomandibular disorders were used. Jaw pain was assessed by two validated screening questions answered with "yes" or "no." A logistic regression analysis was used to predict the outcome variable jaw pain (yes/no) after 2 years.

RESULTS

Whiplash trauma did not increase the odds of development of jaw pain over a 2-year period (OR 1.97, 95% CI 0.53-7.38). However, non-specific physical symptoms (OR 8.56, 95% CI 1.08-67.67) and female gender (OR 4.89, 95% CI 1.09-22.02) did increase the odds for jaw pain after 2 years.

CONCLUSION

The development and maintenance of jaw pain after whiplash trauma are primarily not related to the trauma itself, but more associated with physical symptoms.

CLINICAL RELEVANCE

The development of jaw pain in connection with a whiplash trauma needs to be seen in a biopsychosocial perspective, and early assessment is recommended.

Are Whiplash-Associated Disorders and Temporomandibular Disorders in a Trauma Related Cause and Effect Relationship? A Review

Background: Whiplash is associated with a wide variety of clinical manifestations, including headache, neck pain, cervical rigidity, shoulder and back pain, paresthesia, vertigo, and temporomandibular disorders (TMDs). Previous studies reported that TMDs are more common in individuals with chronic whiplash-associated disorders (WAD) than in the general population; however, the pathophysiology and mechanism of this relationship are still not well understood. Methods: A PubMed and Ovid EMBASE review was performed to identify all studies addressing the trauma related cause and effect relationship between WAD and TMDs from January 2003 to March 2023. Results: After screening for eligibility and inclusion criteria, a total of 16 articles met the selection criteria. The various included studies discussed different aspects of the association between WDA and TMDs, including changes in the coordination and amplitude of jaw opening, the severity of the associated symptoms/signs in cases of WAD, the degree of fatigue and psychological stress, difficulty in feeding, cervical and myofascial pain, changes in the MRI signal at various muscle points, muscle tenderness, and quality of life. Conclusions: In this review, we summarized the clinical evidence of any trauma related cause and effect relationship between whiplash and TMDs. An accurate screening of the previous literature showed that, in conclusion, the relationship between whiplash and TMDs is still unclear.

Incident injury is strongly associated with subsequent incident temporomandibular disorder: results from the OPPERA study

Cross-sectional studies confirm, as expected, a positive association between jaw injury and painful temporomandibular disorders (TMDs), but prospective evaluations are lacking. We prospectively assessed incident jaw injury, injury type, and development of TMD in adults aged 18 to 44 years. Data were collected from 3258 individuals from communities surrounding 4 US academic institutes between 2006 and 2008. At enrollment, participants reported no TMD history and no facial injuries in the previous 6 months. Quarterly, follow-up questionnaires assessed incident jaw injury, which was classified as intrinsic (attributed to yawning or prolonged mouth opening) or extrinsic (attributed to other causes). Examiners classified incident TMD during a median follow-up period of 2.8 years (range 0.2-5.2 years). Cox regression models used jaw injury as a time-dependent covariate to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association with incident TMD. Among 1729 participants with complete data, 175 developed TMD. Eighty percent of injuries were intrinsic. Temporomandibular disorder annual incidence was nearly twice as high in those experiencing jaw injury (5.37%) compared with those who did not (3.44%). In the Cox model that accounted for timing of injury, the corresponding HR was 3.94 (95% CI = 2.82-5.50) after adjusting for study site, age, race, and sex. Hazard ratios did not differ (P = 0.91) for extrinsic injuries (HR = 4.03, 95% CI = 2.00-8.12) and intrinsic injuries (HR = 3.85, 95% CI = 2.70-5.49). Jaw injury was strongly associated with incident TMD. If surveillance and intervention after jaw injury is to be effective in preventing TMD, they should focus on both intrinsic and extrinsic injuries.

Pain Sensitivity Modifies Risk of Injury-Related Temporomandibular Disorder

This study evaluates contributions of jaw injury and experimental pain sensitivity to risk of developing painful temporomandibular disorder (TMD). Data were from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) nested case-control study of incident painful TMD. Injury and subsequent onset of painful TMD were monitored prospectively for ≤5 y in a community-based sample of 409 US adults who did not have TMD when enrolled. At baseline, thermal-pressure and pinprick pain sensitivity, as potential effect modifiers, were measured using quantitative sensory testing. During follow-up, jaw injury from any of 9 types of potentially traumatic events was determined using quarterly (3-monthly) health update questionnaires. Study examiners classified incident painful TMD, yielding 233 incident cases and 176 matched controls. Logistic regression models, estimated incidence odds ratios (IORs), and 95% confidence limits (CLs) were used for the association between injury and subsequent onset of painful TMD. During follow-up, 38.2% of incident cases and 13.1% of controls reported 1 or more injuries that were 4 times as likely to be intrinsic (i.e., sustained mouth opening or yawning) as extrinsic (e.g., dental visits, whiplash). Injuries due to extrinsic events (IOR = 7.6; 95% CL, 1.6–36.2), sustained opening (IOR = 5.4; 95% CL, 2.4–12.2), and yawning (IOR = 3.4; 95% CL, 1.6–7.3) were associated with increased TMD incidence. Both a single injury (IOR = 6.0; 95% CL, 2.9–12.4) and multiple injuries (IOR = 9.4; 95% CL, 3.4,25.6) predicted greater incidence of painful TMD than events perceived as noninjurious (IOR = 1.9; 95% CL, 1.1–3.4). Injury-associated risk of painful TMD was elevated in people with high sensitivity to heat pain (IOR = 7.4; 95% CL, 3.1–18.0) compared to people with low sensitivity to heat pain (IOR = 3.9; 95% CL, 1.7–8.4). Jaw injury was strongly associated with elevated painful TMD risk, and the risk was amplified in subjects who had enhanced sensitivity to heat pain at enrollment. Commonly occurring but seemingly innocuous events, such as yawning injury, should not be overlooked when judging prognostic importance of jaw injury.

The Course of Orofacial Pain and Jaw Disability After Whiplash Trauma: A 2-year Prospective Study

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

The aim of this study was to evaluate the course of orofacial pain and jaw disability in relation to neck pain, neck disability, and psychosocial factors at the acute stage and the chronic stage after whiplash trauma.

SUMMARY OF BACKGROUND DATA

Many individuals report chronic pain in the orofacial region after whiplash trauma. The possible association between whiplash trauma and orofacial pain is debated. Prospective studies are therefore needed to evaluate the development of orofacial pain after whiplash trauma.

METHODS

Within 1 month following a whiplash trauma, 176 cases were examined and compared to 116 controls with questionnaires concerning neck and jaw pain and related disability, nonspecific physical symptoms and depression. At the 2-year follow-up, 119 cases (68%) and 104 controls (90%) were re-examined.

RESULTS

Compared to controls, cases reported more jaw and neck pain, both at baseline and follow-up. A majority (68%) of cases with pain in the jaw region in the acute stage also reported jaw pain at the follow-up. The intensity of jaw and neck pain was correlated both at baseline and follow-up. Both neck pain and jaw pain were correlated to nonspecific physical symptoms and to depression.

CONCLUSION

Orofacial pain and jaw disability related to neck pain are often present already at the acute stage after whiplash trauma and persist into the chronic stage for most individuals. Assessment following whiplash trauma should therefore include both the neck and the orofacial regions. More studies are needed to further evaluate risk factors for development of orofacial pain after whiplash trauma.

LEVEL OF EVIDENCE

3.

Effects on jaw function shortly after whiplash trauma

Normal jaw function involves muscles and joints of both jaw and neck. A whiplash trauma may disturb the integrated jaw-neck sensory-motor function and thereby impair chewing ability; however, it is not known if such impairment is present shortly after a neck trauma or develops over time. The aim was to evaluate jaw function after a recent whiplash trauma. Eighty cases (47 women) were examined within 1 month after a whiplash trauma and compared to 80 controls (47 women) without neck trauma. Participants completed the Jaw disability checklist (JDC) and Neck Disability Index (NDI) questionnaires and performed a 5-minute chewing test. Elicited fatigue and pain during chewing were noted, and group differences were evaluated with Fisher's exact test and Mann-Whitney U-test. Compared to controls, cases had higher JDC (P < .0001) and NDI scores (15% vs 2%, P < .0001), and reported more fatigue (53% vs 31%, P = .006) and pain (30% vs 10%, P = .003) during the chewing test. Cases also had a shorter onset time for fatigue and pain (both P = .001) Furthermore, cases reporting symptoms during chewing had higher JDC and NDI scores compared to cases not reporting symptoms (both P = .01). Symptoms mainly occurred in the trigeminal area for both groups, but also in spinal areas more often for cases than for controls. Taken together, the results indicate that jaw-neck sensory-motor function is impaired already within 1 month after a whiplash trauma. The association between neck disability and jaw impairment underlines the close functional relationship between the regions, and stresses the importance of multidisciplinary assessment.

Pain and Disability in the Jaw and Neck Region following Whiplash Trauma

The relationship between whiplash trauma and chronic orofacial pain is unclear, especially with regard to the time elapsed from trauma to development of orofacial pain. The aim was to analyze prevalence of jaw pain and disability, as well as the relationship between pain and disability in the jaw and neck regions in the early nonchronic stage after whiplash trauma. In this case-control study, 70 individuals (40 women, 30 men, mean age 35.5 y) who visited an emergency department with neck pain following a car accident were examined within 3 wk of trauma (group 1) and compared with 70 individuals (42 women, 28 men, mean age 33.8 y), who declined to attend a clinical examination but agreed to fill in questionnaires (group 2). The 2 case groups were compared with a matched control group of 70 individuals (42 women, 28 men, mean age 37.6 y) without a history of neck trauma. All participants completed questionnaires regarding jaw pain and dysfunction, rating pain intensity in jaw and neck regions on the Numerical Rating Scale, the Neck Disability Index, and Jaw Disability Checklist. Compared with controls, individuals with a recent whiplash trauma reported more jaw pain and dysfunction. Furthermore, there was a moderate positive correlation between jaw and neck pain ratings for group 1 (r = 0.61, P < 0.0001) and group 2 (r = 0.59, P < 0.0001). In the logistic regression analysis, cases showed higher odds ratios (range, 6.1 to 40.8) for jaw and neck pain and disability compared with controls. Taken together, the results show that individuals with a recent whiplash trauma report more jaw pain and disability compared with controls without a history of neck trauma. Furthermore, the correlation between jaw and neck pain intensity implies that intensity of neck pain in the acute stage after whiplash trauma might be a possible risk factor also for development of chronic orofacial pain.

The prevalence of temporomandibular disorders in patients with late whiplash syndrome who experience orofacial pain: a case-control series study

BACKGROUND

The authors conducted a study to compare the frequency of specific temporomandibular disorder (TMD) diagnoses in patients who had late whiplash syndrome (LWS) with that in a control group.

METHODS

The authors recruited 65 patients who had orofacial pain and a previous diagnosis of LWS and 65 age- and sex-matched control patients who had chronic orofacial pain without a history of whiplash injury (WI) for a case-control series study. All patients completed a questionnaire pertaining to the Research Diagnostic Criteria for Temporomandibular Disorders and underwent a clinical examination.

RESULTS

The authors compared the frequency of TMD diagnoses in case patients with that in control patients by using a χ(2) test; they set the α level a priori at .05. The number of patients diagnosed with myofascial pain (MP) and disk displacement with reduction (DDWR) was significantly higher in the case group than in the control group (P = .002 and P = .001, respectively).

CONCLUSIONS

The results of this study show a higher frequency of MP and DDWR in patients with LWS than in patients with chronic orofacial pain and no history of WI. Practical Implications. Clinicians should be knowledgeable about the correlation between WI and TMD so they can inform and treat patients accurately.

Altered thermal sensitivity in facial skin in chronic whiplash-associated disorders

There is a close functional relationship between the jaw and neck regions and it has been suggested that trigeminal sensory impairment can follow whiplash injury. Inclusion of manageable routines for valid assessment of the facial sensory capacity is thus needed for comprehensive evaluations of patients exposed to such trauma. The present study investigated facial thermal thresholds in patients with chronic whiplash-associated disorders (WADs) with both a qualitative method and quantitative sensory testing (QST). Ten women with pain and dysfunction following a whiplash injury were compared to 10 healthy age-matched women. Thermal detection thresholds were assessed by qualitative chair-side testing and by QST according to the method-of-limits. Seven test sites in the facial skin (overlying each trigeminal branch bilaterally, and the midpoint of the chin) were examined. The detection warm and cold thresholds were defined as the mean values of 10 individual thresholds. For the WAD patients, the qualitative assessment demonstrated both reduced and increased sensitivity compared to the healthy, whereas QST systematically showed significantly higher detection thresholds (i.e., decreased sensitivity) for both cold and warm stimuli. For the individuals who were assessed as having increased sensitivity in the qualitative assessment, the QST displayed either normal or higher thresholds, i.e., decreased sensitivity. The results suggest that QST is more sensitive for detecting thermal sensory disturbances in the face than a qualitative method. The impaired thermal sensitivity among the patients corroborates the notion of altered thermal detection capacity induced by WAD-related pain.

Persistent orofacial muscle pain

The pathophysiology of persistent orofacial myalgia has been the centre of much controversy. In this article we suggest a novel descriptive term; 'persistent orofacial muscle pain' (POMP) and review current evidence that supports the hypothesis that the induction of POMP involves the interplay between a peripheral nociceptive source in muscle, a faulty central nervous system component and decreased coping ability. In this context it is widely accepted that a complex interaction of variable intrinsic and extrinsic factors act to induce POMP and dysfunction.

[Can orthodontic treatment generate temporomandibular disorders and pain? A review]

While considered for years to play the primary role in the etiology of temporo-mandibular joint disturbances (TMD), occlusal discrepancies are now considered to be just one causative factor among many. Recent studies, literature reviews or meta-analyses, and longitudinal studies with follow-up of children treated for many years all conclude that there is no risk of orthodontic treatment giving rise to episodes of temporo-mandibular disorders. The signs of TMD appearing during the course of orthodontic treatment should be considered in the context of the epidemiology of the disorder, which is characterized by a strong increase in its occurrence during adolescence. In conclusion, it should be stated that if orthodontic treatment can no longer be considered as one of the etiopathogenic factors in the TMD complex, there are no scientific arguments to justify the converse, that there are indications for orthodontic treatment whose sole goal would be the treatment of TMD.

The relationship of whiplash injury and temporomandibular disorders: a narrative literature review

OBJECTIVE

The purpose of this article is to offer a narrative review and discuss the possible relationship between temporomandibular disorders (TMDs) and whiplash injuries.

METHODS

Databases from 1966 to present were searched including PubMed; Manual, Alternative, and Natural Therapy Index System; and Cumulative Index for Nursing and Allied Health Literature. Search terms used included whiplash injury, temporomandibular disorders and craniomandibular disorders. Inclusion criteria consisted of studies on orofacial pain of a musculoskeletal origin addressing the following topics: posttraumatic temporomandibular disorder (pTMD) incidence and prevalence, mechanism of injury, clinical findings and characteristics, prognosis (including psychologic factors). Excluded were studies of orofacial pain from nontraumatic origin, as well as nonmusculoskeletal causes including neurologic, vascular, neoplastic, or infectious disease.

RESULTS

Thirty-two studies describing the effects of whiplash on TMD were reviewed based on inclusion/exclusion criteria. The best evidence from prospective studies indicates a low to moderate incidence and prevalence. Only 3 studies addressed mechanism of injury theories. Most studies focusing on clinical findings and characteristics suggest significant differences when comparing pTMD to idiopathic/nontraumatic patients. Regarding prognosis, most studies suggest a significant difference when comparing pTMD to idiopathic/nontraumatic TMD patients, with pTMD having a poorer prognosis.

CONCLUSIONS

There is conflicting evidence regarding the effects of whiplash on the development of TMD. Furthermore, because of lack of homogeneity in the study populations and lack of standardization of data collection procedures and outcomes measured, this review cannot conclusively resolve the controversies that exist concerning this relationship. This review of the literature is provided to clarify the issues and to provide useful clinical information for health care providers managing TMD such as doctors of chiropractic, physical therapists, dentists, and medical doctors.

Do occlusal splints have an effect on complex regional pain syndrome? A randomized, controlled proof-of-concept trial

OBJECTIVES

Studies have suggested overlaps between various chronic pain conditions and painful temporomandibular disorders (TMDs). The objective of this pilot study was to assess the effectiveness of occlusal splint (OS) therapy on self-reported measures of pain in patients with chronic complex regional pain syndrome (CRPS) as compared with a nontreatment group.

METHODS

The design was a prospective randomized controlled clinical trial. Twenty patients with CRPS were randomly assigned to either the OS or control group. The patients in the OS group were asked to use the OS at nighttime and for 3 hours during daytime for a total of 7 weeks; the control group had no stomatognathic intervention. The primary outcome was self-reported assessment of CRPS-related pain on numerical rating scales. Secondary outcome measures were the Temporomandibular Index (TMI), and the Short Form 36 Health Survey (SF-36).

RESULTS

All patients had TMD signs and symptoms, but OS had no effect on CRPS-related pain on the numerical rating scale (P>0.100). The changes in the TMI scores over time were 16.6%+/-24.6% (improvement) in the OS group and -21.3%+/-25.9% (impairment) in the control group that was significant (P=0.004). There were no differences in the changes of SF-36 scores between groups (P=0.636).

DISCUSSION

The use of OS for 7 weeks has no impact on CRPS-related pain but improved signs and symptoms of TMD pain. Future studies should include an active control group and evaluate if long-term changes in measures of oral health impact general health in CRPS-related pain.

Reduced or painful jaw movement after collision-related injuries

BACKGROUND

The authors report the incidence of and factors associated with reduced and/or painful jaw movement after motor vehicle collisions that resulted in whiplash-associated disorders (WADs).

METHODS

All adults filing collision-related personal injury claims during an 18-month period in Saskatchewan, Canada, were evaluated via questionnaire to determine demographic characteristics, precollision health (including jaw pain), collision parameters and collision-related symptoms, including reduced and/or painful jaw movement and injury-related neck pain. The authors excluded patients who were hospitalized for more than two days and those who sustained injuries as a pedestrian, bicyclist or motorcyclist. In determining incidence rates, the authors also excluded those who had had jaw pain before the collision.

RESULTS

The incidence of reduced and/or painful jaw movement was 14.9 percent (n = 1,158), and it was higher in subjects with WADs (15.8 percent) than in those without WADs (4.7 percent; relative risk = 3.36, 95 percent confidence interval, 2.36 to 4.78). Within the WAD injuries, multivariable logistic regression revealed that the onset of reduced and/or painful jaw movement was associated with female sex; age < 50 years; having hit one's head in the collision; and postinjury symptoms of difficulty swallowing, ringing in the ears, dizziness or unsteadiness, and more intense neck pain. Collision parameters, such as head position at the time of the crash and headrest use and type, were not associated with onset of jaw symptoms.

CONCLUSIONS

Reduced or painful jaw movement was more common in people with WADs than in those with other collision-related injuries. Among those with WADs, reduced or painful jaw movement was more common in women and younger people.

CLINICAL IMPLICATIONS

Reduced or painful jaw movement is an important aspect of WADs, and more studies are needed to determine how to best assess and treat this problem.

Influence of sympathetic nervous system on sensorimotor function: whiplash associated disorders (WAD) as a model

There is increasing interest about the possible involvement of the sympathetic nervous system (SNS) in initiation and maintenance of chronic muscle pain syndromes of different aetiology. Epidemiological data show that stresses of different nature, e.g. work-related, psychosocial, etc., typically characterised by SNS activation, may be a co-factor in the development of the pain syndrome and/or negatively affect its time course. In spite of their clear traumatic origin, whiplash associated disorders (WAD) appear to share many common features with other chronic pain syndromes affecting the musculo-skeletal system. These features do not only include symptoms, like type of pain or sensory and motor dysfunctions, but possibly also some of the pathophysiological mechanisms that may concur to establish the chronic pain syndrome. This review focuses on WAD, particular emphasis being devoted to sensorimotor symptoms, and on the actions exerted by the sympathetic system at muscle level. Besides its well-known action on muscle blood flow, the SNS is able to affect the contractility of muscle fibres, to modulate the proprioceptive information arising from the muscle spindle receptors and, under certain conditions, to modulate nociceptive information. Furthermore, the activity of the SNS itself is in turn affected by muscle conditions, such as its current state of activity, fatigue and pain signals originating in the muscle. The possible involvement of the SNS in the development of WAD is discussed in light of the several positive feedback loops in which it is implicated.