Incidence of temporomandibular joint symptoms following whiplash injury

Patterns of Head and Neck Injuries in Urban India: A Multicenter Study

Objective

The pattern of head and neck injuries has been well studied in high-income countries, but the data are limited in low- and middle-income countries, which are disproportionately affected by trauma. We examined a prospective multicenter database to describe patterns and outcomes of head and neck injuries in urban India.

Study Design

Retrospective review of trauma registry.

Setting

Four tertiary public hospitals in Mumbai, Delhi, Kolkata.

Methods

We identified patients with isolated head and neck injuries using International Classification of Diseases, 10th Revision (ICD-10) codes and excluded those with traumatic brain and/or ophthalmic injuries and injuries in other body regions.

Results

Our cohort included 171 patients. Most were males (80.7%) and adults aged 18 to 55 years (60.2%). Falls (36.8%) and road traffic accidents (36.3%) were the 2 predominant mechanisms of injury. Overall, 35.7% required intensive care unit (ICU) admission, and 11.7% died. More than 20% of patients were diagnosed with “unspecified injury of neck.” Those with the diagnosis had a higher ICU admission rate (51.4% vs 31.3%, P = .025) and mortality rate (27.0% vs 7.5%, P = .001) than those without the diagnosis.

Conclusion

Isolated head and neck injuries are not highly prevalent among Indian trauma patients admitted to urban tertiary hospitals but are associated with high mortality. Over a fifth of patients were diagnosed with “unspecified injury of neck,” which is associated with more severe clinical outcomes. Exactly what this diagnosis entails and encompasses remains unclear.

Retrospective analysis of trauma incidence in patients with temporomandibular disorders

BACKGROUND/AIM

The relationships between direct trauma, whiplash injuries, and temporomandibular disorders (TMD) have not been well established. The aim of this study was to evaluate the percentage of direct and/or whiplash trauma in patients with TMDs.

MATERIAL AND METHODS

The clinical records of 237 patients with temporomandibular disorders who had sought treatment at the Orofacial Pain Clinic were reviewed. Clinical data for age and gender of the patients, history of trauma, temporomandibular joint (TMJ) sounds, and TMD diagnosis were extracted from the medical records of all included patients. The presence of TMJ sounds and TMD diagnosis had been determined based on the Research Diagnostic Criteria for TMDs.

RESULTS

The mean age of patients with osteoarthritis was significantly higher than that of patients with disk displacement with reduction (P = .001, P ˂ .05). There was no statistically significant gender-based difference in diagnosis, clicking, crepitus, and trauma frequency (P > .05). A history of direct and whiplash trauma was observed in 18.6% and 14.8% of patients, respectively. Statistical analysis for the relationship between clicking and crepitus, and trauma showed no significant correlation (P > .05).

CONCLUSION

Direct and/or whiplash trauma in patients with temporomandibular disorders were not associated with the diagnostic records and temporomandibular joint sounds.

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.

Head and Neck Trauma in a Rapidly Growing African Metropolis: A Two-Year Audit of Hospital Admissions

Understanding injury-related burdens is an essential part of trauma quality improvement programs aimed at decreasing morbidity and mortality. This is especially the case in low and middle-income country settings where data on injuries remains limited. The aim of this study was to audit the types of head and neck injuries, which have been diagnosed among patients admitted to a major national hospital in the context of a rapidly growing sub Saharan city. Data were collected retrospectively for head and neck trauma from the Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania from the years 2016 and 2017. Distribution of ICD-10 codes by age and sex for the five most common diagnoses were determined using frequencies and percentages. The most common diagnosis was ICD-10-S02 (fracture of skull and facial bones) with 277 cases (44.1%), which was followed by S05 (injury of the eye and orbit), 114 cases (18.2%), and S09 (other and unspecified injuries of head) 77 cases (12.3%). The mean ages of admission for these three diagnoses were 28.1 (SD: 11.6), 23.8 (SD: 18.9), and 30.8 (SD: 18.0) years, respectively. This study provides information on the overall burden of head and neck trauma at a major regional tertiary care facility. It provides an initial understanding of the burden of head and neck trauma and suggests follow-up in the form of clarification of injury mechanisms and contextual factors for future work.

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.

Dynamic 3D FE modelling of the human temporomandibular joint during whiplash

Rear-end impacts account for more than one-third of vehicle accidents, and nearly 40% of these accidents produce whiplash injuries. Whiplash injury to the neck has often been considered a significant risk factor for the development of temporomandibular disorders (TMD). The objective of this study was to simulate the dynamic response of the temporomandibular joint during two types of impacts: a rear end and a frontal impact. To understand the dynamic forces acting on the joint, we extended a previous human temporomandibular joint model and analyzed the stress distributions in the soft elements of the joint. In the rear-end impact, it could be appreciated that the inertia of the mandible caused it to move posteriorly slower than the head, and this resulted in downward and forward displacements of the disc-condyle complex relative to the cranial base. Consequently, a rapid and big mouth opening occurs. In contrast, during the frontal impact, the mouth hardly opened, because the superior maxilla pushed the mandible to move together. There was not differential movement between bony components of the joint and therefore the soft tissues of the joint were not subjected to high loads. From these results, and despite the limitations of the simulations performed, we could conclude that neither a rear-end impact at low-velocity nor a frontal impact would produce damage to the soft tissues of the joint.

Radiographic and clinical features of temporomandibular dysfunction in patients following indirect trauma: A retrospective study

OBJECTIVES

Patients developing temporomandibular dysfunction (TMD) following a motor vehicle accident (MVA) have been reported to respond poorly to standard TMD treatment compared with TMD patients who have not sustained an MVA. The purpose of this study was to determine clinical and radiographic differences between post-MVA and nontrauma TMD patients and to determine whether radiographic findings in post-MVA patients undergoing litigation show more severe anatomical changes than post-MVA patients not undergoing litigation.

STUDY DESIGN

One hundred thirty-six files with magnetic resonance imaging (MRI) and/or bone scan studies of TMD patients were randomly drawn (54 post-MVA and 82 nontrauma TMD).

RESULTS

Patients with post-MVA TMD demonstrated significantly more orofacial pain complaints but significantly less disk displacements on MRI (47.5% post-MVA vs. 69.2% control; P = .03). Litigating post-MVA patients had significantly more nonreducing disks than the nonlitigating group (37.7% litigating vs. 7.7% nonlitigating; P = .05).

CONCLUSION

Based on these findings, it is suggested that treatment limited to the temporomandibular joints (TMJs) in post-traumatic TMD patients may fail without consideration that pain may originate in structures other than the TMJs. Within the post-MVA group, the more severe anatomical changes were found in the litigating patients, suggesting that some of their symptoms are associated with anatomical changes.

Delayed temporomandibular joint pain and dysfunction induced by whiplash trauma: a controlled prospective study

BACKGROUND

The Quebec Task Force on Whiplash-Associated Disorders urged for controlled, prognostic studies of symptoms after whiplash trauma. The authors conducted a study that met the design requirements to enhance knowledge about short-term and long-term temporomandibular joint (TMJ) pain, dysfunction or both induced by whiplash trauma.

METHODS

The authors studied 60 consecutive patients who had neck symptoms after whiplash trauma and were seen at a hospital emergency department. They followed up 59 subjects one full year later. At the inceptive examination and at follow-up, each subject completed a self-administered questionnaire, followed by a comprehensive interview. Fifty-three frequency-matched control subjects followed the same protocol concurrently.

RESULTS

The incidence of new symptoms of TMJ pain, dysfunction or both between the inceptive examination and follow-up was five times higher in subjects (34 percent) than in control subjects (7 percent). The frequency of TMJ pain increased significantly in female subjects, as did the frequency of TMJ symptoms that were reported to be the main complaint. At the follow-up, 20 percent of all subjects reported that TMJ symptoms were their main complaint.

CONCLUSIONS

Our results suggest that one in three people who are exposed to whiplash trauma is at risk of developing delayed TMJ symptoms that may require clinical management.

CLINICAL IMPLICATIONS

Awareness of a significant risk for delayed onset of TMJ symptoms after whiplash trauma is crucial for making adequate diagnoses, prognoses and medicolegal decisions.

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.

Motion Analysis of the Mandible during Low-Speed, Rear-End Impacts using High-Speed X-rays

There has been much debate over "whiplash"-induced temporomandibular joint (TMJ) dysfunction following low-speed, rear-end automobile collisions. While several authors have reported TMJ injury based on case studies post collision, there has been little biomechanical evidence showing that rear-end impact was the primary cause of such injury. The purpose of this study was to measure the relative translation between the upper and lower incisors in cadavers subjected to low-speed, rearend impacts. High-speed x-ray images used for this analysis were reported previously for the analysis of cadaveric cervical spine kinematics during low-speed, rear-end impacts. The cadavers were positioned at various seatback angles and body postures, producing an overall picture of various seating scenarios. Of the 38 tests conducted using 10 cadavers, there were seven tests from three cadavers in which the positions of the upper and lower incisors could be tracked with precision using imageprocessing software. The relative protrusion, retrusion, and mouth opening were computed from these seven sets of data, providing a better understanding of TMJ motion. Based on this limited data, the average maximum protrusion, retrusion and mouth opening were 1.6+/-1.8, 1.1+/-0.7, and 1.2+/-1.2 mm, respectively. These values appear to fall within normal physiological limits experienced during daily activities such as mastication. It is concluded that low-speed, rear-end automobile collisions do not appear to create the motion required to initiate injury to the TMJ.

Sensory and affective components of orofacial pain: is it all in your brain?

In this paper, we shall review several chronic orofacial pain conditions with emphasis on those that are essentially refractory to treatment. We shall present a review of current and past literature that describes the various pain phenomena as well as their underlying central mechanisms. New data concerning refractory pain will be used to underscore the importance of central processing of pain, with particular emphasis on neuropsychological and cognitive function and capacity that may play important roles in pain processing and maintenance of the pain state. Further, neurophysiological data showing that the anterior cingulate cortex (ACC) and other structures in the brain may play key roles in modulation of chronic pain will also be discussed. Although peripheral triggering events surely play an important role in initiating pain, the development of chronic and, in particular, refractory pain may depend on changes or malfunctions in the central nervous system. These changes may be quite subtle and require sophisticated approaches, such as functional MRI, to study them, as is now being done. New findings obtained therefore may lead to more rational and reliable treatment for orofacial pain.

Whiplash: a review of a commonly misunderstood injury

Whiplash injury is a relatively common occurrence, but its mechanism and optimal treatment remain poorly understood. It is estimated that the incidence of whiplash injury is approximately 4 per 1,000 persons. The most common radiographic findings include either preexisting degenerative changes or a slight flattening of the normal lordotic curvature of the cervical spine. Computed tomography and magnetic resonance imaging are generally reserved for cases of neurologic deficit, suspected disc or spinal cord damage, fracture, or ligamentous damage. Biomechanics studies have determined that after rear impact C6 is rotated back into extension before movement of the upper cervical vertebrae. Thus, the lower cervical vertebrae were in extension while the upper vertebrae were in a position of relative flexion, producing an S shape in the cervical spine. It is believed that this abnormal motion pattern might play a role in the development of whiplash injuries. Historically, a soft cervical collar has been used early after the injury in an attempt to restrict cervical range of motion and limit the chances of further injury. More recent studies report rest and restriction of motion to be detrimental and to slow the healing process.

Applying the Quebec Task Force criteria as a frame of reference for studies of whiplash injuries

Research prior to 1995 showed a diversity of either inclusion or exclusion criteria (or both) for diagnosing whiplash injury. As a consequence, the Quebec Task Force (QTF) developed expert-based criteria, which may be considered as a the 'new' gold standard. Here, we examined the inclusion criteria and exclusion criteria used in research populations from the major 82 research studies performed during the period 1980-1998, comparing their similarities and dissimilarities to the QTF standard. None of the articles satisfied the QTF definitions completely, either before or after their introduction in 1995. Nevertheless, the QTF still seems to have had some impact on either the published inclusion or exclusion criteria. We observed that both sets of criteria showed a qualitative shift following the QTF publication in 1995. For the inclusion criteria, we found both a statistically significant increase in use of the QTF definition (acceleration-deceleration mechanism, rear-end collision, motor vehicle collision or other mishaps) and in the criterion 'neck pain'. We also observed some smaller changes in both inclusion and exclusion criteria but none of these was significant statistically.

The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept

PURPOSE

This article re-evaluates the chain of events leading to temporomandibular joint (TMJ) disc displacement. The joint lubrication system and the process of its breakdown are clarified and an attempt is made to evaluate the possible effect of increased friction between the disc and fossa on the anterior displacement of the disc.

MATERIALS AND METHODS

The study is based on the author's accumulated clinical data and results obtained from laboratory investigations regarding TMJ lubrication and its possible breakdown, coupled with pertinent information culled from the literature.

RESULTS

Translation of the disc in the TMJ is enabled due to the presence of phospholipids and hyaluronic acid, which constitute an efficient lubrication system. This system may break down in the presence of uncontrolled free radicals. In the absence of lubricants, the articular surfaces are smooth, elastic in texture, and possess strong surface energy. Such opposing planes, especially in the presence of a thin fluid film (sub-boundary lubrication) tend to generate high friction while the disc is sliding against the fossa. Such friction is probably the prime mover in loosening the disc attachments to the condyle, with subsequent disc displacement.

CONCLUSIONS

Increased friction of the contiguous parts may well be a major causative factor in displacement of the articular disc. This should be taken into account in considering the appropriate treatment approach. It also raises some doubts regarding the validity of using repositioning techniques.

Extraoral facial pain

Craniofacial pain is a common chief complaint and is among the most frustrating diagnostic and treatment challenges encountered by emergency physicians. The efficient development of a differential diagnosis, the delivery of appropriate and effective therapies, and the appropriate referral of patients who present with craniofacial pain from extraoral sources are discussed. Disease descriptions, a diagnostic workup format, and acute management protocols are presented for the more common craniofacial pain entities.

The craniocervical connection: a retrospective analysis of 300 whiplash patients with cervical and temporomandibular disorders

Because the concept of whiplash as a causative factor for temporomandibular disorders (TMD) is highly controversial, we decided to do a retrospective analysis of patients treated in our office who had sustained whiplash injuries and were treated for cervical and temporomandibular disorders. The records of 300 patients with TMD preceded by a motor vehicle accident were examined retrospectively. The most common presenting symptoms, in order, were: jaw pain, neck pain, post-traumatic headache, jaw fatigue, and severe temporomandibular joint (TMJ) clicking. The most common TMD diagnoses were: masseter trigger points, closing jaw muscle hyperactivity, TMJ synovitis, opening jaw muscle hyperactivity, and advanced TMJ disk derangement. Based primarily on the physical examination, we concluded that the TMJ and surrounding musculature should be examined similarly to other joints, with no preconceived notion that TMD pathology after whiplash is unlikely.

Medical legal considerations in temporomandibular disorders

Dentists commonly see patients with temporomandibular disorders who are involved in litigation, and dentists are occasionally accused of temporomandibular disorder-related negligence. Rapidly changing scientific knowledge must be reflected in dental practice and in the courtroom, where dentists act as experts. In this article, concepts pertaining to assessments of patients with temporomandibular disorders for impairment and disability and concepts pertaining to legal causation are discussed, especially in relation to motor vehicle accidents. Recommendations for avoiding malpractice suits are presented.

Prevalence of temporomandibular disorders associated with whiplash injury in Lithuania

OBJECTIVE

The purpose of this study was to ascertain the prevalence of symptoms of temporomandibular disorders in whiplash victims in Lithuania and compare it with the prevalence in otherwise healthy control subjects.

STUDY DESIGN

In a controlled historical cohort study in Lithuania, we asked each of 210 victims of vehicular rear-end collisions (at 14-27 months after the accident) to report the presence and frequency of a number of temporomandibular disorder symptoms. The results were compared with those for an age-matched and gender-matched control group, sampled randomly from the local population.

RESULTS

In the accident group, 2.4% of subjects (4/165) reported jaw pain for 1 day or more per month; this compared with 3.3% of the controls (6/180). One (0.6%) of the accident victims and 2 (1.1%) of the controls had daily jaw pain. In both groups there was a low prevalence of jaw sounds, pain in or near the ear(s), jaw locking, tinnitus, and facial pain.

CONCLUSIONS

Unlike whiplash claimants in many Western societies, Lithuanian accident victims do not appear to report the chronic symptoms of temporomandibular disorders despite their acute whiplash injuries.

A review and methodologic critique of the literature refuting whiplash syndrome

The validity of whiplash syndrome has been a source of debate in the medical literature for many years. Some authors have published articles suggesting that whiplash injuries are impossible at certain collision speeds; others have stated that the problem is psychological, or is feigned as a means to obtain secondary financial gain. These articles contradict the majority of the literature, which shows that whiplash injuries and their sequelae are a highly prevalent problem that affects a significant proportion of the population. The authors of the current literature critique reviewed the biomedical and engineering literature relating to whiplash syndrome, searching for articles that refuted the validity of whiplash injuries. Twenty articles containing nine distinct statements refuting the validity of whiplash syndrome were found that fit the inclusion criteria. The methodology described in these articles was evaluated critically to determine if the authors' observations regarding the validity of whiplash syndrome were scientifically sound. The authors of the current critique found that all of the articles contained significant methodologic flaws with regard to their respective authors' statements refuting the validity of whiplash syndrome. The most frequently found flaws were inadequate study size, nonrepresentative study sample, nonrepresentative crash conditions (for crash tests), and inappropriate study design. As a result of the current literature review, it was determined that there is no epidemiologic or scientific basis in the literature for the following statements: whiplash injuries do not lead to chronic pain, rear impact collisions that do not result in vehicle damage are unlikely to cause injury, and whiplash trauma is biomechanically comparable with common movements of daily living.

Whiplash and temporomandibular disorders: a critical review

Some authors have hypothesized a relationship between rear-impact motor vehicle collisions and subsequent symptoms of neck pain and temporomandibular disorders, or TMD, despite no facial impact. This article examines the TMD aspect in terms of the physiological basis and cultural factors influencing the reporting of such symptoms.

Concurrent cervical and craniofacial pain. A review of empiric and basic science evidence

Because many patients present themselves for treatment with both craniofacial and craniocervical pain, 2 questions arise: (1) What are the sensory and motor consequences of dysfunction in either of these areas on the other? (2) Do craniofacial and craniocervical pain have a similar cause? These questions formed the impetus for this review article. The phenomenon of concurrent pain in craniofacial and cervical structures is considered, and clinical reports and opinions are presented regarding theories of cervical-to-craniofacial and craniofacial-to-cervical pain referral. Because pain referral between these 2 areas requires anatomic and functional connectivity between trigeminally and cervically innervated structures, basic neurophysiologic and neuroanatomic literature is reviewed. The published data clearly demonstrate neurophysiologic and structural convergence of cervical sensory and muscle afferent inputs onto trigeminal subnucleus caudalis nociceptive and non-nociceptive neurons. Moreover, changes in metabolic activity and blood flow in the brainstem and cervical dorsal horn of the spinal cord in both monkeys and cats have been demonstrated after electric stimulation of the V1-innervated superior sagittal sinus. In conclusion, the animal experimental data support the findings of human empiric and experimental studies, which suggest that strong connectivity exists between trigeminal and cervical motor and sensory responses.

Whiplash injuries of the temporomandibular joint in motor vehicle accidents: speculations and facts

Referring to the temporomandibular joint (TMJ) of the human mandibular locomotor system, it has been asserted that displacement of the TMJ disc and inflammation of TMJ tissues are the results of acute and indirect trauma to the TMJ; on occasion this is allegedly experienced in motor vehicle accidents and commonly known as a TMJ whiplash injury. It is postulated that the TMJ whiplash injury is released in the occupant or occupants of a target vehicle when its rear end is impacted by the front end of a bullet vehicle. On the basis of detailed analyses of TMJ trauma/pain histories and TMJ magnetic resonance images, presented as circumstantial evidence in favour of the postulated TMJ whiplash injury, and detailed analyses of the mathematical biophysics of the mandibular locomotor system as well as direct experimental evidence, it is concluded that the postulated TMJ whiplash injury does not exist as a single and independent disease entity caused by motor vehicle accidents. If TMJ disc displacement and inflammation are present, they are expressions of an insidious and progressive pre-existing (pre-accident) disease entity that is comprised of TMJ synovitis/osteoarthritis (phase of inflammation with presence of immune system cells), TMJ internal derangement (phase of disc displacement and deformation with presence of proteinases), and TMJ osteoarthrosis (phase of degeneration with absence of immune system cells). For the asserted TMJ whiplash manoeuvre and ensuing injury to occur as postulated, the laws of physics and biology would have to be suspended.

Head, neck, and mandible dynamics generated by 'whiplash'

That injuries to the temporomandibular joint (TMJ) can be imposed by short-acting forces generated during rear-end collisions of motor vehicles was first proposed more than 50 years ago. Since that time, numerous anecdotal and clinical reports relating the onset of TMJ symptoms to low-velocity rear-end collisions have appeared in the literature. Various mechanisms of injury to the TMJ occurring during extension and flexion phases of 'whiplash' have been proposed. However, transient forces developed at the TMJ in impact velocity changes on the order of 8.0 kilometers per hour (km/h) have been shown to be well within typical physiologic ranges. This study applies current head/neck extension-flexion dynamic data to develop linear and angular force-time histories experienced at the TMJ. Fourteen test collisions of motor vehicles utilizing seven live test subjects were conducted in July 1993. Linear and angular accelerometers and high-speed photographic cameras recorded the vehicle and human-subject responses. Head accelerations and forces generated at the TMJ bore a generally linear relationship to the impact velocity changes in the range tested (3.9-10.9 km/h). Mandibular opening responses were measured on three test subjects. Neither neck hyperflexion nor hyperextension occurred for any subject on any trial. At some point in the series, all test subjects experienced neck muscle strain symptoms lasting 1-3 days. No TMJ symptoms were experienced. The head, neck, and mandible motions occurring in the 'whiplash' maneuver are more complex than previously described. The cervical muscle injury threshold appears to be reached in the 8.0 km/h range. Linear and rotational forces generated at the TMJ in rear-end impacts below the 11.0 km/h velocity-change level do not appear to be injurious.

Effect of impact and injury characteristics on post-motor vehicle accident temporomandibular disorders

OBJECTIVES

The objective of this study was to assess the potential effects of motor vehicle accident impact and injury characteristics on post-motor vehicle accident temporomandibular disorders in terms of presenting signs and symptoms, diagnoses, treatment regimens, and outcomes.

STUDY DESIGN

A retrospective chart review of 50 patients with post-motor vehicle accident temporomandibular disorders from a private oral medicine practice was undertaken. Various demographic data and data related to temporomandibular disorders and motor vehicle accident impact and injury characteristics were collected. Chi-square and Fisher exact tests and multiple regression analyses were performed.

RESULTS

Patients involved in front-end collisions or motor vehicle accidents resulting in severe vehicle damage reported more direct orofacial injury. However, those in rear-end collisions or accidents resulting in minimal vehicle damage required more treatment. Direct head or orofacial injury was therefore not a prognostic indicator. From multiple regression analyses, indicators of a poorer prognosis were minimal vehicle damage, lack of headrest use, driver position, and settlement of insurance claim.

CONCLUSIONS

In this patients group several prognostic indicators for patients with post-motor vehicle accident temporomandibular disorders were identified; these indicators may influence the management approach for this patient population.

Traumatic onset of temporomandibular disorders: positive effects of a standardized conservative treatment program

OBJECTIVE

To compare presenting problems and response to treatment of chronic temporomandibular (TMD) patients who perceive the onset of their symptoms to be related to trauma with those who report symptoms of unknown origin.

DESIGN

Prospective treatment outcome study.

SETTING

Outpatient multidisciplinary pain treatment center at a university medical center.

PATIENTS

A total of 361 were evaluated initially, including 103 who perceived traumatic onset of symptoms and 258 who did not perceive onset to be related to trauma. Two hundred thirty-three (59 trauma and 174 nontrauma) returned for follow-up evaluation 6 months after the conclusion of treatment.

INTERVENTIONS

Standardized six-session treatment program consisting of intraoral appliance, biofeedback, and stress management training.

OUTCOME MEASURES

Clinical changes in muscle pain, temporomandibular joint pain, and mandibular opening. Self-report of change in perceived pain severity (MPQ--short form), depressive symptoms (BDI), catastrophizing about pain (CSQ--catastrophizing scale), MPI--interference scale, oral parafunctional habits, global evaluation of improvement, and use of pain medications at follow-up.

RESULTS AND CONCLUSIONS

Regression of onset type on pretreatment variables indicated that a small but statistically significant proportion of pretreatment variability (8.7%) could be accounted for by onset. Both traumatic and nontraumatic onset groups showed positive outcomes following treatment. No significant differences between groups were found for any of the clinical or self-reported outcome measures with the exception that a significantly higher percentage of the trauma group reported using pain medication at follow-up. These findings are in contrast with previous suggestions that post-traumatic TMD patients show poorer response to treatment than nontrauma TMD patients.

Temporomandibular disorders, headaches, and neck pain after motor vehicle accidents: a pilot investigation of persistence and litigation effects

STATEMENT OF PROBLEM

There is a lack of long-term follow-up studies that involve post-motor vehicle accident temporomandibular disorders and compensation.

PURPOSE OF STUDY

The purposes of this retrospective pilot study were (1) to assess patients who had previously been treated for temporomandibular disorders after motor vehicle accidents to determine the nature of their symptoms in terms of jaw, head, and neck pain and jaw dysfunction and (2) to determine whether there was a difference in the pain and dysfunction between those who had settled and those who had not settled their insurance claims.

MATERIAL AND METHODS

Thirty previously treated patients with temporomandibular disorders after motor vehicle accidents were questioned by telephone regarding litigation status and current jaw, head, and neck pain and jaw dysfunction symptoms. They did not differ substantially from a smaller group who were not able to be interviewed. Descriptive statistics were calculated and statistical tests were performed. A total of 22 patients had their claims settled.

RESULTS

Approximately three fourths had persistent complaints of jaw pain, jaw dysfunction, and headache, and more than 80% reported persistent neck pain. No apparent differences were found between those who had and had not settled their insurance claims.

CONCLUSION

Jaw, head and neck pain, and jaw dysfunction continued to be problems for the majority of this patient population, regardless of litigation status in this retrospective study.

The relationship between cervical whiplash and temporomandibular joint injuries: an MRI study

Temporomandibular joint (TMJ) symptoms are a common finding in motor vehicle accident (MVA) patients with hyperextension/hyperflexion injuries of the cervical spine (cervical whiplash). The relationship between cervical whiplash and TMJ injuries was documented with magnetic resonance imaging (MRI) in 87 consecutive MVA cervical whiplash patients who presented with TMJ symptoms and had sustained no direct trauma to the face, head or mandible and had no TMJ complaints prior to the MVA. One hundred sixty-four TMJ patients were evaluated for internal derangement, effusion and inflammation, utilizing T1 and T2 weighted images. A high percentage of the TMJ patients demonstrated abnormal findings: disk displacement with reduction (DDR), 118/164 (72%); disk displacement without reduction (DDNR), 25/164 (15%); effusion, 113/164 (69%); inflammation or edema, 84/164 (51%); total TMJ abnormalities, 156/164 (95%). The high percentage of TMJ abnormalities in this study significantly illustrates the proximate relationship between cervical whiplash and TMJ injuries.

Temporomandibular joint injury potential imposed by the low-velocity extension-flexion maneuver

PURPOSE

It has been proposed that significant temporomandibular joint injury can occur as a result of rapid extension-flexion motion of the neck (whip-lash). This motion, which is experienced by passengers in vehicles that undergo rear-end collisions, has been described as causing rapid protrusion and opening of the mandible. It has been speculated that this relative motion between the mandible and the cranium produces forces at the temporomandibular joint (TMJ) that injure the articular elements. The objective of this study was to measure these forces by an experimental method.

MATERIALS AND METHODS

Accelerometer sensor and high-speed cinematographic data were obtained from the kinematic responses of live human test subjects positioned as occupants in motor vehicles that underwent staged low-velocity rear-end collisions. Linear and moment forces generated at the TMJs were obtained from the resultant acceleration pulse at the craniomandibular complex, estimation of the mass properties of the mandible and its appended soft tissues, and the application of Newton's Second Law of motion.

RESULTS

The maximum linear forces generated at the TMJ in a rear-end collision resulting in a velocity change of the test subject of 8 km/h (5 mph) were in the 7 to 10 N (1.6 to 2.2 lb) range. Moment forces at the joint peaked briefly at 0.55 N.m (4.81 lb-in).

CONCLUSIONS

These force magnitudes generated at the TMJ constitute a minor fraction of the forces experienced at the joint during normal physiologic function. It is a conclusion of this study that injuries to the TMJ attributed to low-velocity "whiplash" cannot be accounted for by the joint forces produced by this maneuver.

Temporomandibular pain dysfunction disorder resulting from road traffic accidents--an Australian study

The relationship between temporomandibular pain dysfunction disorder (TMPD) and trauma to the head and neck is unclear. A retrospective analysis of the records from the Transport Accident Commission (TAC) of Victoria, Australia, in the year 1987, was done to identify those subjects who received treatment for TMPD resulting from a road traffic accident (RTA). Twenty-eight subjects with TMPD were identified from a total of 20 673 subjects who claimed health care services from the TAC for RTA-related disorders. In this study, TMPD for which subjects sought treatment was uncommonly associated with either direct or indirect trauma to the temporomandibular joints: 0.4% of subjects with mandibular fractures and 0.5% of subjects with whiplash injuries presented for treatment of an associated TMPD. Females were found to present for treatment of TMPD more commonly than males at a ratio of 5:2. It was also noted that 75% of subjects complained of symptoms of TMPD immediately after the accident and approximately 96% within 2 months of the accident. Subjects were not lost to follow-up because all claims for treatment were made to the TAC, regardless of the clinician involved. In this study, 25% of subjects attended more than one dentist for management. It was concluded that TMPD for which subjects sought treatment was an uncommon result of an RTA and was infrequently associated with a mandibular fracture or whiplash injury.