- Email: [email protected]
Kinematics of head movement and onset of sternocleidomastoid muscle activity in simulated low-velocity rear-end impacts
OOOOE April 2005
438 Abstracts ROLE OF INTRAMUSCULAR pH IN MYOFASCIAL PAIN OF THE MASTICATORY MUSCLES. D. T. Hamamoto, and J. R. Luderitz, University of Minnesota School of Dentistry, Minneapolis, Minn. Background. Myofascial pain is a regional muscle pain disorder characterized by localized muscle pain. The pathophysiologic mechanisms that underlie myofascial pain are poorly understood. One potential mechanism is the activation of muscle nociceptors by localized tissue acidosis. Objectives. The aim of this study was to compare extracellular pH in the most painful and least painful areas of the masseter muscle in subjects with and without myofascial pain of the masticatory muscles. Study design. Fourteen subjects met the Research Diagnostic Criteria for Temporomandibular Disorders classification of myofascial pain of the masticatory muscles and reported pain in at least 1 masseter muscle. Palpation of that masseter muscle duplicated their clinical jaw pain. Fourteen age-matched control subjects had no history of TMJ pain or limited mandibular opening. A calibrated examiner performed the clinical examinations, and the results were used to calculate the temporomandibular index (TMI). A pressure algometer was used to determine pressure pain thresholds in 1 masseter muscle at 2 sites, 1 with the least pain and 1 with the most pain to digital palpation. An angiocatheter was placed through anesthetized skin into the masseter muscle at 1 of the sites and contact with muscle was verified using an EMG unit. Extracellular pH was measured using a calibrated microelectrode. A computer recorded intramuscular pH every 5 seconds for 2 minutes. Results. Subjects with myofascial pain reported higher symptom severity in the masticatory muscles than did control subjects (P \ .001). The TMI was higher for subjects with myofascial pain (0.49 6 0.03) than for control subjects (0.14 6 0.03; P \ .001). Palpation of the masseter muscle evoked pain more frequently in subjects with myofascial pain (87%) than in control subjects (19%; P \ .001). Pressure pain threshold in the masseter muscle at the most painful site was lower in subjects with myofascial pain (97.4 6 9.5 kPa) than in control subjects (143.0 6 17.7 kPa; P \.05). Pressure pain threshold at the most painful site in subjects with myofascial pain was also lower than that at the least painful site in control subjects (161.1 6 15.5 kPa; P \.01). There was no significant difference in intramuscular pH between the least painful (7.40 6 0.17) and most painful (7.22 6 0.08) sites for subjects with myofascial pain or for control subjects (least painful, 7.30 6 0.09; most painful, 7.25 6 0.09). Conclusions. Intramuscular pH did not differ between the most and least painful sites in the masseter muscles of subjects with myofascial pain and control subjects. Intramuscular pH does not appear to contribute to pain associated with myofascial pain of the masticatory muscles. This study was supported by a UM Graduate School Grantin-Aid (#18604) and a grant from the American Academy of Orofacial Pain.
KINEMATICS OF HEAD MOVEMENT AND ONSET OF STERNOCLEIDOMASTOID MUSCLE ACTIVITY IN SIMULATED LOW-VELOCITY REAR-END IMPACTS. I. A. Herna´ndez, K. Fyfe, G. Heo, I. Ikram, and P. W. Major, University of Alberta, Edmonton, Alberta. Objectives. Rear-end impacts and whiplash injuries are highly associated. More than a million whiplash injuries occur each year in the US.1 The kinematics of head movement in
simulated rear-end impacts has been described. However, the influence of impact awareness remains controversial. In addition, the suggestion that cervical muscles activate too late in rear-end impacts may be incorrect.2 The goal of this study was to analyze the kinematics of head movement in rear-end impacts related to 2 impact magnitudes, impact awareness and onset of sternocleidomastoid (SCM) muscle response. Study design. The Human Research Ethics Board at the University of Alberta approved this study. Thirty subjects completed the study. Each subject underwent 3 impacts: 1 slow unexpected (4.5 m/sec/sec), 1 fast unexpected (10.0 m/sec/sec), and 1 fast expected impact of the same magnitude as the fast unexpected impact. Kinematics of head movement was simultaneously recorded with a custom accelerometer board and the use of video cameras. Angular head displacement, and angular and linear head acceleration were recorded. Normalized SCM surface electromyography (EMG) was obtained. Onset and peak time for the EMG and the kinematics were determined. Onset time was defined as the time in which 5% of the magnitude value of the peak occurred. Peak time was defined as the time in which the maximum value of the variable was reached. Repeated-measures statistical method was used to analyze the head movement behavior associated with impact velocity and expectation. The same statistical method was used to determine whether muscle activity or head movement was initiated first. Results. The video camera and accelerometer data presented a good agreement. Subjects presented an initial rearward movement in which the head moved backward followed by a forward movement of the head. The rearward angular head displacement almost doubled (;13 degrees) with increased impact magnitude (P \ .05). The peak magnitude of rearward and forward angular acceleration increased 2 to 3 times with increased impact magnitude (P \ .05). Rearward and forward linear displacement was 2.5-3.5 times higher for the fast than the slow unexpected impacts (P \ .05). There were no significant differences in the magnitude of angular head acceleration, angular head displacement, and linear head acceleration regarding awareness (P [0.05). The onset time of SCM peak EMG ranged from 78-114 ms later than peak of linear head acceleration for all groups (P \.05). The onset of the SCM peak EMG ranged from 136-188 ms earlier than the peak rearward angular head displacement in all impacts (P \ .05). Onset time of peak SCM EMG was significantly earlier (30 ms) than the peak angular head acceleration for the fast unexpected impact (P \ .05). Conclusions. Kinematics of head movement increased with increased impact magnitude. Magnitude of angular head displacement was within physiologic limits and do not support the hyperextension theory. Temporal and amplitude awareness did not produce different magnitude in kinematics of head movement. The temporal relationship between the SCM and angular head acceleration is different from the temporal relationship between the SCM and linear head acceleration. The authors would like to support Dr S Kumar for use of his lab, equipment, and technical support. This research was supported by the University of Alberta Fund for Dentistry Grant #2002-02 and McIntyre Memorial Research fund.
REFERENCES 1. Malleson A. Chronic whiplash syndrome. Psychosocial epidemic. Canadian Family Physician 1994;40:1906-9.
OOOOE Volume 99, Number 4 2. Siegmund GP, Brault JR, Wheeler JB. The relationship between clinical and kinematic responses from human subject testing in rear-end automobile collisions. Accident Analysis & Prevention 2000;32:207-17.
THE ANALYSIS OF DYSESTHESIA REPORTED BY 276 DENTISTS AFTER TOOTH EXTRACTION AND IMPLANT SURGERY. J. Ryu, J. H. Shin, S. Kim, and J. H. Choi, Yonsei University Dental College, Seoul, South Korea. Objectives. Neuropathies can affect a single nerve or several nerves and result in sensory, motor, and/or autonomic deficits in the affected region. Reported dental causes of dysesthesia include tooth extractions, implant placement, needle trauma following local anesthesia, periapical inflammation, denture compression of the nerve, and endodontic treatment. In many cases reviewed, tooth extraction was the main cause of dysesthesia in orofacial region. Moreover, there has been a dramatic increase in the number of practitioners performing implant surgery over the past 15 years. The acceptance of challenging cases may increase the incidence of related problems and complications. The number of malpractice suits related to implants and tooth extractions has increased significantly, with awards among the highest in dentistry. Altered mandibular sensation following implant surgery or extraction may result in liabilaty claims. Therefore, it seems prudent to review these cases to better understand the causes and characterization of such actions to prevent complications and reduce future litigation. Study design. Questionnaires were delivered to people who attended implant seminars directly and returned at that time; 276 questionnares were returned. There were 16 questions, 8 of which related to tooth extraction and 8 to implant surgery. Results. Tooth extraction: Of the 276 dentists, 108 (39.1%) experienced dysesthetic patients after tooth extraction. Rate of persistent dysesthesia reported by respondents was 14.6%. The most frequent problem associated was pain and a burning sensation. Implant surgery: Of the 276 dentists, 68 (24.6%) experienced dysesthetic patients after implant surgery. Rate of persistent dysesthesia reported by respondents was 25.4%. The most frequent problem associated was pain and a burning sensation. Conclusions. In this study, most dysesthesia may be resolved within 1 year. However, 14%-25% of dysesthesia may be persistent. The oral and perioral regions are known to be among the most sensitive areas in the human body. This explains why minor oral nerve damage can be a major handicap for the patients. Most dysesthetic pain resolves spontaneously over 1-2 years. While the pain is present, however, a patient’s quality of life can be substantially diminished.
A PRELIMINARY EVALUATION OF THE SURFACE OF SURGICALLY REMOVED PROPLAST/TEFLON INTERPOSITIONAL DISC IMPLANTS FROM HUMAN TEMPOROMANDIBULAR JOINTS. J. Requicha-Ferreira, S. Myers, C.-C. Ko, J. Swift, and J. Fricton, University of Minnesota School of Dentistry, Minneapolis, Minn. Objectives. The scientific literature has presented evidence that wear debris of temporomandibular joint (TMJ) interpositional disc (ID) implants follows implant failure and results in progressive osseous erosion of the TMJ and chronic orofacial pain. The purpose of this study is to investigate the surface structure of removed human TMJ ID implants, because wear debris appears to result from structural collapse of TMJ ID.
Abstracts 439 Methods. Four surgically retrieved Proplast/Teflon TMJ ID implants from 3 patients, who had the implants in for greater than 15 years, were previously collected through the National Institute of Dental and Craniofacial Research TMJ Implant Registry and Repository (NIDCR TIRR) and were selected for analysis. The implants, previously stripped of all patient identifiers, were stored in 10% buffered formalin or 4% paraformaldeyde immediately after surgical removal. Implants were washed thoroughly with distilled water prior to observation with a Leica S6D stereo zoom microscope (0.63343). Surface characteristics of each implant were documented using a digital camera (Leica DFC280). The number of surface perforations, position of any central perforation, and fragmentation were documented. The presence or absence of surface scratches was also noted. The characterized features were then correlated with selected deidentified clinical findings. The clinical findings from NIDCR TIRReconsenting patients was recorded 1 to 3 months prior to the implants’ surgical removal. Results. All implants were perforated with traces of surface scratch on the polymeric (Teflon) surface. The largest perforations were located near the center of the implant. TMJ ID implant failure patterns also include Teflon-layer fragmentation and detaching of the 2 layers of the implant. Severe fragmentation with fiber extrusion was observed in 2 implants. Clinical findings revealed all patients had TMJ pain on the implant side on maximum assisted jaw opening, maximum unassisted jaw opening \38 mm, and lateral excursive movement limitation towards the normal joint side. The patient who had severe fragmented implants described feelings of a foreign body migration at the joint. TMJ CT scan reports showed hypertrophic changes, flattening, bone resorption, fragmentation, subcondral cysts on the condyle, and a perforation into the medial cranial fossa. MRI evaluations showed significant osteolysis of the condylar head and severe glenoid fossa resorption, close to perforating the middle cranial fossa. Conclusions. Polymeric breakdown particles (implant wear debris) appear to trigger a degenerative reaction resulting in pain and limitation on the dynamics of the TMJ, similar to those described in previous studies.1,2 Further analysis of an expanded sample of retrieved implants will continue and be presented at the meeting. Histopathologic and immunochemical methods to analyze these implants are under way to test this hypothesis and study underlying failure mechanisms of TMJ ID implants. Deidentified implant materials were provided by the NIDCR TIRR: NIH/NIDCR TIRR N01-DE-22635.
REFERENCES 1. Trumpy IG, Lyberg T. Temporomandibular joint dysfunction and facial pain caused by neoplasms. Report of three cases. Oral Surg Oral Med Oral Path 1993;76:149-52. 2. Feinerman DM, Piecuch JF. Long-term retrospective analysis of twenty-three Proplast-Teflon temporomandibular joint interpositional implants. Int J Oral Maxillofac Surg 1993;22:11-6.
APPLICATION OF ID MIGRAINE AS A SELF-ADMINISTERED SCREENING INSTRUMENT FOR MIGRAINE IN THE OROFACIAL PAIN CLINIC: KOREAN EXPERIENCE. S. Kim, S. Mitrirattanakul, and R. Merrill, Yonsei University School of Dentistry, Seoul, South Korea; Mahidol University, Bangkok, Thailand; and University of California School of Dentistry, Los Angeles, Calif. Objectives. To evaluate the use of ID Migraine as a selfadministered screening instrument for migraine in the orofacial pain clinic setting.
438 Abstracts ROLE OF INTRAMUSCULAR pH IN MYOFASCIAL PAIN OF THE MASTICATORY MUSCLES. D. T. Hamamoto, and J. R. Luderitz, University of Minnesota School of Dentistry, Minneapolis, Minn. Background. Myofascial pain is a regional muscle pain disorder characterized by localized muscle pain. The pathophysiologic mechanisms that underlie myofascial pain are poorly understood. One potential mechanism is the activation of muscle nociceptors by localized tissue acidosis. Objectives. The aim of this study was to compare extracellular pH in the most painful and least painful areas of the masseter muscle in subjects with and without myofascial pain of the masticatory muscles. Study design. Fourteen subjects met the Research Diagnostic Criteria for Temporomandibular Disorders classification of myofascial pain of the masticatory muscles and reported pain in at least 1 masseter muscle. Palpation of that masseter muscle duplicated their clinical jaw pain. Fourteen age-matched control subjects had no history of TMJ pain or limited mandibular opening. A calibrated examiner performed the clinical examinations, and the results were used to calculate the temporomandibular index (TMI). A pressure algometer was used to determine pressure pain thresholds in 1 masseter muscle at 2 sites, 1 with the least pain and 1 with the most pain to digital palpation. An angiocatheter was placed through anesthetized skin into the masseter muscle at 1 of the sites and contact with muscle was verified using an EMG unit. Extracellular pH was measured using a calibrated microelectrode. A computer recorded intramuscular pH every 5 seconds for 2 minutes. Results. Subjects with myofascial pain reported higher symptom severity in the masticatory muscles than did control subjects (P \ .001). The TMI was higher for subjects with myofascial pain (0.49 6 0.03) than for control subjects (0.14 6 0.03; P \ .001). Palpation of the masseter muscle evoked pain more frequently in subjects with myofascial pain (87%) than in control subjects (19%; P \ .001). Pressure pain threshold in the masseter muscle at the most painful site was lower in subjects with myofascial pain (97.4 6 9.5 kPa) than in control subjects (143.0 6 17.7 kPa; P \.05). Pressure pain threshold at the most painful site in subjects with myofascial pain was also lower than that at the least painful site in control subjects (161.1 6 15.5 kPa; P \.01). There was no significant difference in intramuscular pH between the least painful (7.40 6 0.17) and most painful (7.22 6 0.08) sites for subjects with myofascial pain or for control subjects (least painful, 7.30 6 0.09; most painful, 7.25 6 0.09). Conclusions. Intramuscular pH did not differ between the most and least painful sites in the masseter muscles of subjects with myofascial pain and control subjects. Intramuscular pH does not appear to contribute to pain associated with myofascial pain of the masticatory muscles. This study was supported by a UM Graduate School Grantin-Aid (#18604) and a grant from the American Academy of Orofacial Pain.
KINEMATICS OF HEAD MOVEMENT AND ONSET OF STERNOCLEIDOMASTOID MUSCLE ACTIVITY IN SIMULATED LOW-VELOCITY REAR-END IMPACTS. I. A. Herna´ndez, K. Fyfe, G. Heo, I. Ikram, and P. W. Major, University of Alberta, Edmonton, Alberta. Objectives. Rear-end impacts and whiplash injuries are highly associated. More than a million whiplash injuries occur each year in the US.1 The kinematics of head movement in
simulated rear-end impacts has been described. However, the influence of impact awareness remains controversial. In addition, the suggestion that cervical muscles activate too late in rear-end impacts may be incorrect.2 The goal of this study was to analyze the kinematics of head movement in rear-end impacts related to 2 impact magnitudes, impact awareness and onset of sternocleidomastoid (SCM) muscle response. Study design. The Human Research Ethics Board at the University of Alberta approved this study. Thirty subjects completed the study. Each subject underwent 3 impacts: 1 slow unexpected (4.5 m/sec/sec), 1 fast unexpected (10.0 m/sec/sec), and 1 fast expected impact of the same magnitude as the fast unexpected impact. Kinematics of head movement was simultaneously recorded with a custom accelerometer board and the use of video cameras. Angular head displacement, and angular and linear head acceleration were recorded. Normalized SCM surface electromyography (EMG) was obtained. Onset and peak time for the EMG and the kinematics were determined. Onset time was defined as the time in which 5% of the magnitude value of the peak occurred. Peak time was defined as the time in which the maximum value of the variable was reached. Repeated-measures statistical method was used to analyze the head movement behavior associated with impact velocity and expectation. The same statistical method was used to determine whether muscle activity or head movement was initiated first. Results. The video camera and accelerometer data presented a good agreement. Subjects presented an initial rearward movement in which the head moved backward followed by a forward movement of the head. The rearward angular head displacement almost doubled (;13 degrees) with increased impact magnitude (P \ .05). The peak magnitude of rearward and forward angular acceleration increased 2 to 3 times with increased impact magnitude (P \ .05). Rearward and forward linear displacement was 2.5-3.5 times higher for the fast than the slow unexpected impacts (P \ .05). There were no significant differences in the magnitude of angular head acceleration, angular head displacement, and linear head acceleration regarding awareness (P [0.05). The onset time of SCM peak EMG ranged from 78-114 ms later than peak of linear head acceleration for all groups (P \.05). The onset of the SCM peak EMG ranged from 136-188 ms earlier than the peak rearward angular head displacement in all impacts (P \ .05). Onset time of peak SCM EMG was significantly earlier (30 ms) than the peak angular head acceleration for the fast unexpected impact (P \ .05). Conclusions. Kinematics of head movement increased with increased impact magnitude. Magnitude of angular head displacement was within physiologic limits and do not support the hyperextension theory. Temporal and amplitude awareness did not produce different magnitude in kinematics of head movement. The temporal relationship between the SCM and angular head acceleration is different from the temporal relationship between the SCM and linear head acceleration. The authors would like to support Dr S Kumar for use of his lab, equipment, and technical support. This research was supported by the University of Alberta Fund for Dentistry Grant #2002-02 and McIntyre Memorial Research fund.
REFERENCES 1. Malleson A. Chronic whiplash syndrome. Psychosocial epidemic. Canadian Family Physician 1994;40:1906-9.
OOOOE Volume 99, Number 4 2. Siegmund GP, Brault JR, Wheeler JB. The relationship between clinical and kinematic responses from human subject testing in rear-end automobile collisions. Accident Analysis & Prevention 2000;32:207-17.
THE ANALYSIS OF DYSESTHESIA REPORTED BY 276 DENTISTS AFTER TOOTH EXTRACTION AND IMPLANT SURGERY. J. Ryu, J. H. Shin, S. Kim, and J. H. Choi, Yonsei University Dental College, Seoul, South Korea. Objectives. Neuropathies can affect a single nerve or several nerves and result in sensory, motor, and/or autonomic deficits in the affected region. Reported dental causes of dysesthesia include tooth extractions, implant placement, needle trauma following local anesthesia, periapical inflammation, denture compression of the nerve, and endodontic treatment. In many cases reviewed, tooth extraction was the main cause of dysesthesia in orofacial region. Moreover, there has been a dramatic increase in the number of practitioners performing implant surgery over the past 15 years. The acceptance of challenging cases may increase the incidence of related problems and complications. The number of malpractice suits related to implants and tooth extractions has increased significantly, with awards among the highest in dentistry. Altered mandibular sensation following implant surgery or extraction may result in liabilaty claims. Therefore, it seems prudent to review these cases to better understand the causes and characterization of such actions to prevent complications and reduce future litigation. Study design. Questionnaires were delivered to people who attended implant seminars directly and returned at that time; 276 questionnares were returned. There were 16 questions, 8 of which related to tooth extraction and 8 to implant surgery. Results. Tooth extraction: Of the 276 dentists, 108 (39.1%) experienced dysesthetic patients after tooth extraction. Rate of persistent dysesthesia reported by respondents was 14.6%. The most frequent problem associated was pain and a burning sensation. Implant surgery: Of the 276 dentists, 68 (24.6%) experienced dysesthetic patients after implant surgery. Rate of persistent dysesthesia reported by respondents was 25.4%. The most frequent problem associated was pain and a burning sensation. Conclusions. In this study, most dysesthesia may be resolved within 1 year. However, 14%-25% of dysesthesia may be persistent. The oral and perioral regions are known to be among the most sensitive areas in the human body. This explains why minor oral nerve damage can be a major handicap for the patients. Most dysesthetic pain resolves spontaneously over 1-2 years. While the pain is present, however, a patient’s quality of life can be substantially diminished.
A PRELIMINARY EVALUATION OF THE SURFACE OF SURGICALLY REMOVED PROPLAST/TEFLON INTERPOSITIONAL DISC IMPLANTS FROM HUMAN TEMPOROMANDIBULAR JOINTS. J. Requicha-Ferreira, S. Myers, C.-C. Ko, J. Swift, and J. Fricton, University of Minnesota School of Dentistry, Minneapolis, Minn. Objectives. The scientific literature has presented evidence that wear debris of temporomandibular joint (TMJ) interpositional disc (ID) implants follows implant failure and results in progressive osseous erosion of the TMJ and chronic orofacial pain. The purpose of this study is to investigate the surface structure of removed human TMJ ID implants, because wear debris appears to result from structural collapse of TMJ ID.
Abstracts 439 Methods. Four surgically retrieved Proplast/Teflon TMJ ID implants from 3 patients, who had the implants in for greater than 15 years, were previously collected through the National Institute of Dental and Craniofacial Research TMJ Implant Registry and Repository (NIDCR TIRR) and were selected for analysis. The implants, previously stripped of all patient identifiers, were stored in 10% buffered formalin or 4% paraformaldeyde immediately after surgical removal. Implants were washed thoroughly with distilled water prior to observation with a Leica S6D stereo zoom microscope (0.63343). Surface characteristics of each implant were documented using a digital camera (Leica DFC280). The number of surface perforations, position of any central perforation, and fragmentation were documented. The presence or absence of surface scratches was also noted. The characterized features were then correlated with selected deidentified clinical findings. The clinical findings from NIDCR TIRReconsenting patients was recorded 1 to 3 months prior to the implants’ surgical removal. Results. All implants were perforated with traces of surface scratch on the polymeric (Teflon) surface. The largest perforations were located near the center of the implant. TMJ ID implant failure patterns also include Teflon-layer fragmentation and detaching of the 2 layers of the implant. Severe fragmentation with fiber extrusion was observed in 2 implants. Clinical findings revealed all patients had TMJ pain on the implant side on maximum assisted jaw opening, maximum unassisted jaw opening \38 mm, and lateral excursive movement limitation towards the normal joint side. The patient who had severe fragmented implants described feelings of a foreign body migration at the joint. TMJ CT scan reports showed hypertrophic changes, flattening, bone resorption, fragmentation, subcondral cysts on the condyle, and a perforation into the medial cranial fossa. MRI evaluations showed significant osteolysis of the condylar head and severe glenoid fossa resorption, close to perforating the middle cranial fossa. Conclusions. Polymeric breakdown particles (implant wear debris) appear to trigger a degenerative reaction resulting in pain and limitation on the dynamics of the TMJ, similar to those described in previous studies.1,2 Further analysis of an expanded sample of retrieved implants will continue and be presented at the meeting. Histopathologic and immunochemical methods to analyze these implants are under way to test this hypothesis and study underlying failure mechanisms of TMJ ID implants. Deidentified implant materials were provided by the NIDCR TIRR: NIH/NIDCR TIRR N01-DE-22635.
REFERENCES 1. Trumpy IG, Lyberg T. Temporomandibular joint dysfunction and facial pain caused by neoplasms. Report of three cases. Oral Surg Oral Med Oral Path 1993;76:149-52. 2. Feinerman DM, Piecuch JF. Long-term retrospective analysis of twenty-three Proplast-Teflon temporomandibular joint interpositional implants. Int J Oral Maxillofac Surg 1993;22:11-6.
APPLICATION OF ID MIGRAINE AS A SELF-ADMINISTERED SCREENING INSTRUMENT FOR MIGRAINE IN THE OROFACIAL PAIN CLINIC: KOREAN EXPERIENCE. S. Kim, S. Mitrirattanakul, and R. Merrill, Yonsei University School of Dentistry, Seoul, South Korea; Mahidol University, Bangkok, Thailand; and University of California School of Dentistry, Los Angeles, Calif. Objectives. To evaluate the use of ID Migraine as a selfadministered screening instrument for migraine in the orofacial pain clinic setting.