Amitriptyline treatment of chronic pain in patients with temporomandibular disorders.

Randomized clinical trials of amitriptyline will require data from pilot studies to be used for sample size estimates, but such data are lacking. This study investigated the 6-week and 1-year effectiveness of low dose amitriptyline (10-30 mg) for the treatment of patients with chronic temporomandibular disorder (TMD) pain. Based on clinical examination, patients were divided into two groups: myofascial and mixed (myofascial and temporomandibular joint disorders). Baseline pain was assessed by a Visual Analogue Scale (VAS) for pain intensity and by the McGill Pain Questionnaire (MPQ). Depression was assessed by the Beck Depression Inventory (BDI) short form. Patient assessment of global treatment effectiveness was obtained after 6 weeks and 1 year of treatment by using a five-point ordinal scale: (1) worse, (2) unchanged, (3) minimally improved, (4) moderately improved, (5) markedly improved. The results showed a significant reduction for all pain scores after 6 weeks and 1 year post-treatment. The depression scores changed in depressed but not in non-depressed patients. Global treatment effectiveness showed significant improvement 6 weeks and 1 year post-treatment. However, pain and global treatment effectiveness were less improved at 1 year than at 6 weeks.

The relationship between chronic facial pain and a history of trauma and surgery.

OBJECTIVE: Because pain is the most commonly reported symptom of patients presenting to temporomandibular disorders clinics, it is important to identify factors that modify the perception or reality of such pain. The purpose of this study was to investigate the hypothesis that a patient with a history of trauma and/or non-temporomandibular joint surgery might be sensitized to pain and might report increased pain levels if a temporomandibular disorder later developed. STUDY DESIGN: This was a retrospective study of 778 consecutive patients seen over a 1-year period in an Orofacial Pain Clinic. Study parameters included gender, lifetime number of self-reported traumas, lifetime number of non-temporomandibular joint operations, and location, intensity, frequency, and type of temporomandibular disorder-related pain. RESULTS: There were significantly more women than men in the study (609 to 169). There was no relationship between numbers of previous traumas and non-temporomandibular joint operations and types of temporomandibular disorder. However, there were statistically significant relationships between the severity of facial pain and the frequency of facial pain as well as between the severity and frequency of joint pain and the number of traumas. There were also statistically significant associations between the severity and frequency of facial pain and the number of non-temporomandibular joint-related surgical procedures that the patient had undergone. CONCLUSIONS: There is a relationship between a patient's reported history of trauma and/or non-temporomandibular joint-related operations and the severity and frequency of facial and temporomandibular joint pain, should it develop. It is possible that such traumas and operations sensitize the patient in such a way that the pain of subsequent temporomandibular joint disorders is heightened.

Modeling of jaw biomechanics in the reconstructed mandibulectomy patient.

STATEMENT OF PROBLEM: Biomechanics of occlusal force and indirect calculation of temporomandibular joint loading in patients after surgery for head and neck cancer is poorly understood. PURPOSE: This study compared occlusal force values of 6 mandibulectomy subjects with reconstructed mandibles to 6 noncancer subjects with intact mandibles and reports occlusal force predictions from a developed computer model simulation of both a mandibulectomy subject with a reconstructed mandible and noncancer subject with an intact mandible. MATERIAL AND METHODS: Maximum occlusal force was recorded at the first molar and incisal edge in 6 mandibulectomy subjects who had bony reconstruction of the mandible and 6 noncancer subjects with an intact mandible. Clinical data were then qualitatively compared with occlusal force values generated from an existing computer model simulating an average adult, and a developed model simulating an average mandibulectomy subject who had bony reconstruction of the mandible. The biomechanical parameters modeled also included an estimation of joint force magnitude and direction when biting with maximal force on the first molar. RESULTS: Clinical data revealed no significant differences in occlusal force between the 6 mandibulectomy subjects with bony reconstruction of the mandible and 6 noncancer subjects with an intact mandible; however, average molar and incisal occlusal force values were 22% and 32% less in mandibulectomy subjects with bony reconstruction. Computer simulations of a reconstructed mandibulectomy subject predicted that reconstructed subjects would have 45% less molar occlusal force, 50% less incisal occlusal force, and a higher joint/tooth force ratio compared with a simulated noncancer patient with an intact mandible. CONCLUSIONS: There were no significant differences in first molar or incisal occlusal force between reconstructed mandibulectomy subjects and noncancer subjects with intact mandibles. Trends calculated from computer simulations were consistent with clinical findings.

Fracture resistance of endodontically treated teeth restored with bonded amalgam and full crowns.

The use of dentin bonding prior to placement of core build-up restorations has been shown to reduce microleakage and reinforce remaining tooth structure. However, information is lacking about the influence a core build-up has on the fracture resistance of crowned teeth. The purpose of this in-vitro study was to compare the influence of three types of core build-ups on the fracture resistance of crowned teeth.

Gender difference in jaw pain induced by clenching.

Seven normal male and seven normal female volunteers performed three types of biting exercises: an intermittent contraction at maximum voluntary bite force (MVBF) to pain intolerance; a ramp intermittent contraction starting at 10% MVBF and increasing 10% every 10 s; and a sustained biting at 100% MVBF to pain intolerance. The following measurements were made on the first and second days before exercise: a pre- and post-exertional overall jaw pain level; maximum pain-free jaw opening; bilateral masseter pressure pain threshold (PPT) and intolerance (PPI). The results showed that only females presented an increased overall pain level on the second day and a significant decrease in pain-free jaw opening, but no significant decrease of PPT and PPI. These results suggest that females respond differently than males to exertional jaw pain, by increasing their pain response 24 h later.

Bruxing patterns in children compared to intercuspal clenching and chewing as assessed with dental models, electromyography, and incisor jaw tracing: preliminary study.

The purpose of the present study was to compare bruxing patterns in children with chewing and maximum intercuspal clenching as defined in a clinical and laboratory environment. Six non-bruxing controls and six children who actively bruxed according to parent reports were evaluated. Both control and experimental subjects were assessed by an initial questionnaire, intraoral examination, extraoral examination, dental study models, incisor mandibular tracking, and bilateral surface electromyographic recordings (e.g., EMG). Bruxing was defined as grinding, clenching, or both in combination. The clinical examination consisted of an intraoral examination of the dentition, number of occlusal contacts, and wear facets. Dental study models were used to substantiate the intraoral findings for occlusal contact and wear facets. The mandibular incisors position was tracked during opening, closing, laterotrusion, protrusion, and chewing and compared to the bruxing movements in the experimental subjects. Bilateral surface EMG signals from the temporalis and masseter muscles were recorded in three maximum intercuspal clenches, ten chewing cycles on sugarless gum, and during simulated bruxing. The dental contacts were equal in number bilaterally in both control and bruxing subjects. Both groups demonstrated wear facets, but the bruxing subjects had more facets. The wear facets indicated lateral excursions but not clenching. Only the incisor jaw tracking and bilateral EMG differentiated the bruxing patterns. In those subjects (n = 4) who clenched during bruxing, the EMG pattern was not similar to that of intercuspal clenching and demonstrated its own unique muscle recruitment for the temporalis and masseter muscles. In the subjects who exhibited lateral excursions for bruxing (n = 2), the pattern of muscle recruitment of the two-closing muscles in terms of amplitude was similar for both the bruxing and chewing gum. Our findings support a concept that bruxing may depend upon factors that modify coactivation of muscle recruitment and do not depend upon occlusal contacts.

A comparison of masticatory function in patients with or without reconstruction of the mandible.

BACKGROUND: The functional benefits of mandibular reconstruction following a composite resection remain unclear. Although microvascular surgical techniques have dramatically increased the predictability of bone and soft-tissue reconstruction towards presurgical anatomic norms, the specific factors responsible for improved function remain controversial. Objective measures of masticatory function need to be more clearly determined before the predictability and efficacy of reconstructive approaches is established. METHODS: We evaluated objective measures of oral function and patient reports of function in 10 reconstructed mandibulectomy patients, 10 without reconstruction, and 10 controls. Measures of oral function included bite force assessed at the first molar and incisal edge, a measure of tongue and cheek function, and patient reports of food they could eat. RESULTS: Both reconstructed and nonreconstructed patients presented decreased biting force, a more restricted diet, and compromised cheek and tongue function as compared with normals. However, reconstructed patients had significantly better measures of tongue function and ability to eat a varied diet than did nonreconstructed patients. Of the objective measures used to measure masticatory performance, bite force was poorly correlated, whereas measures of tongue function strongly correlated with successful mastication. CONCLUSION: Both reconstructed and nonreconstructed patients presented with a significant functional deficit when compared with normals, with reconstructed patients having better overall function than nonreconstructed patients.

Effect of nonvital tooth bleaching on microleakage of resin composite restorations.

Thirty-six extracted, noncarious, nonfractured human incisors were divided into four groups of nine teeth. Endodontic access cavities were prepared, the pulp chamber was debrided, the root canals were cleansed, and root canal treatment was completed. Pulp cavities of teeth in group 1 received a cotton pellet and were sealed with Cavit. Groups 2, 3, and 4 received a mixture of 30% hydrogen peroxide and sodium perborate for 3, 4, and 7 days, respectively, were sealed with Cavit, and were stored in a humidor until used. Cavit and the other materials were removed, and the cavities were rinsed and restored with Scotchbond Multipurpose and Silux. The teeth were thermocycled, stained with 50% silver nitrate, and sectioned longitudinally. Dye penetration was measured. Results indicated that bleaching adversely affected the marginal seal at the tooth-restoration interface, as evidenced by increased microleakage; the highest rate of microleakage was found after the 7-day application of bleaching materials.

Crevicular fluid analysis around two failing dental implants: a clinical report.

The criteria for monitoring tissue health around endosseous implants remain subjective. Disagreement about which clinical measures of peri-implant health are of diagnostic value continues because of the complexity of the disease process and lack of validated measures of peri-implant health. Crevicular fluid analysis of various inflammatory mediators has been investigated as a means of providing objective criteria of tissue health. In this clinical report, the crevicular fluid levels of interleukin-1 beta (IL-1 beta), an inflammatory cytokine, were used to provide an objective measure of the peri-implant health and the effectiveness of treatment for a patient with two failing implants. The measurement of IL-1 beta may be an important supplement to clinical findings in establishing a diagnosis of peri-implantitis.

The relationship between fibromyalgia and temporomandibular disorders: prevalence and symptom severity.

OBJECTIVE: To determine the prevalence of muscular or myofascial temporomandibular disorders (TMD) in fibromyalgia (FM) and the prevalence of FM in TMD; and to determine which characteristics best distinguish the 2 disorders. METHODS: 39 consecutive patients with TMD seen in a TMD clinic and 60 patients with FM were examined according to Research Diagnostic Criteria (RDC) for TMD and the American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia. All patients completed the questionnaires of the RDC and a health status instrument that assessed pain, function, sleep disturbance, fatigue, and psychological status (CLINHAQ). RESULTS: A small proportion of patients with TMD (18.4%) also had FM, but most of those with FM (75.0%) satisfied criteria for muscular (myofascial) TMD. Patients with FM had lower pain thresholds and more severe manifestations of all disease measures (e.g., pain, fatigue, sleep, etc.) compared to those with TMD. As might be predicted, they also had more painful body regions. Patients with FM also differed significantly from those with TMD in self-reported work ability and health assessment. The features that best differentiate FM from TMD are functional disability, reports of work difficulty, and general dissatisfaction with health. CONCLUSION: TMD is a local disorder and FM a generalized disorder, and there is less evidence of distress in those with TMD. TMD is a separate disorder from FM, but many patients with FM have TMD symptoms.

Patterns of jaw muscle activity during voluntary chewing.

Mastication is controlled by central rhythm and burst generators, but whether this control is similar under automatic and voluntary chewing is not clear. Our first aim was to determine whether increased chewing frequency led to a proportional decrease in both the burst duration (the time of muscle activity) and the interburst interval (time of inactivity) of each muscle or to a minimal decrease in the burst duration and a substantial decrease in the interburst interval. Our second aim was to determine whether these two manifestations of control differed between the opening and closing muscles. Electromyograms from digastric, medial pterygoid, masseter and anterior temporalis muscles were obtained during gum chewing by five subjects at four frequencies. A nearly fourfold decrease in total cycle duration (TCD) with increased chewing frequencies was accompanied by minimal changes in burst duration in the digastric muscle but proportional changes in the jaw closing muscles. The onset latency of the digastric muscle as a percentage of TCD decreased and became negative (i.e. occurred before opening started) as the TCD decreased. The onset latencies of the jaw closing muscles remained roughly 10-20% of the TCD for the three lower chewing frequencies. Control of the opening muscle appears to differ from control of the closing muscles.

Phosphorus magnetic resonance spectroscopy of human masseter muscle.

Masseter muscle metabolism is poorly understood. 31P Magnetic Resonance Spectroscopy (MRS) provides an opportunity for non-invasive study of muscle metabolism during rest, exercise, and recovery. The aim of this study was to investigate the changes in high-energy phosphates and pH in human masseter muscle associated with exertional pain. Phosphates and pH were measured with 31P Magnetic Resonance at 2.0 Tesla. The bite force was simultaneously measured with a force transducer. Continuous biting at maximum voluntary bite force (MVBF) and two intermittent biting exercises with different duty cycles were performed to pain intolerance. The light intermittent exercise did not produce pain. Brief MVBF requested at the beginning, during, and end of each exercise showed no decay. Qualitatively, changes in phosphates were similar to those reported from comparable limb muscle exercises: increased inorganic phosphate (Pi), decreased phosphocreatine (PCr), and no changes in ATP level. Quantitatively, however, the Pi/PCr ratio did not reach the levels reported in limb muscles during similar exercises. Also, the pH changed very little. Thus, the lack of fatigue was no surprise, since the level of changes in Pi/PCr and pH, reported to be associated with fatigue in limb muscles, was far less in the masseter. Pain development toward the end of the heavy exercises prevented further depletion of metabolites. Thus, the lack of fatigue generally postulated for the masseter muscle may not be due to resistance to fatigue of these fibers, but rather to the presence of pain preventing the fatigue. However, no specific metabolic changes associated with exertional pain were found.

Kinematics of jaw movements during chewing at different frequencies.

The three-dimensional jaw movement trajectory and its velocity profile were investigated to provide information regarding the motor control of chewing. This was done on a cycle-by-cycle basis across three voluntarily guided chewing frequencies to test the lack of invariance at the velocity level and the evidence for a cost function. The data revealed that an increase in chewing frequencies resulted in a significant reduction of the three-dimensional path, being significantly higher in opening than closing. The ratio of peak speed/three-dimensional distance, a kinematic index of stiffness, increased with increase in chewing frequency; higher stiffness being associated with faster chewing, the stiffness being significantly higher in opening than in closing. The ratio of peak velocity to mean velocity decreased as a function of increase in chewing frequency only at the highest frequency and this decrease again was different in opening than in closing. The results demonstrated that the velocity profile of chewing movements, like that of speech movements, lacked invariance. Rather than minimizing one cost function, the system used an efficient trade-off between time, space and effort, based on the objective of movements.

Axiographic tracings of temporomandibular joint movements.

Three-dimensional condylar movements of 49 symptomatic and asymptomatic volunteers were recorded with a hinge axis tracing system axiograph during maximal opening, protrusion, and mediotrusion. The tracings displayed in sagittal and frontal planes were measured to evaluate biomechanics of the temporomandibular joint. The only differences in condylar tracings between symptomatic and asymptomatic groups were in the right joint, recorded in the sagittal plane during maximal opening, and the Bennett angle. The symptomatic group had a significantly longer condylar path and a smaller Bennett angle compared with the asymptomatic group. The results were interpreted as indications of adaptive morphologic instead of pathologic changes. The alterations in condylar tracings as an indicator of joint pathology should be considered cautiously.

Prosthetic rehabilitation in temporomandibular disorder and orofacial pain patients. Clinical problem solving.

Good clinical decision making represents an integral part of quality care. A definition of the dental problem and its significance from a dental point of view, in combination with a good working hypothesis of the nature of the concurrent TMD condition are prerequisites of any successful clinical problem solving. It is hoped that, with time, we will be in a position to call upon hard data on the probability and utility of successful outcome for each treatment alternative. This will bring the needed structure and scientific validity to a terribly complex albeit clinically important problem.

Signs and symptoms in samples with and without temporomandibular disorders.

Factors commonly associated with signs and symptoms of temporomandibular disorder were investigated in two groups. The patient group consisted of 41 subjects seeking treatment at the UCSF Temporomandibular Disorders Clinic, and the control group consisted of 40 incoming and first-year students. Questionnaires and clinical examinations were used to identify and measure factors in the areas of history, functional signs, and occlusion. Only four factors emerged as statistically significant between groups: frequent headaches, masticatory muscle tenderness, cervical muscle tenderness, and maximum opening.

Devices for the diagnosis and treatment of temporomandibular disorders. Part I: Introduction, scientific evidence, and jaw tracking.

This three-part series of articles summarizes the uses of several devices or groups of devices intended for the diagnosis or treatment of temporomandibular disorders (TMD) and compares their claimed clinical usefulness with the present scientific evidence. Part I of this review defines TMD; discusses the principal criteria for evaluating published scientific clinical evidence such as reliability, validity, sensitivity, and specificity; gives a rationale for the clinical "gold standard" against which diagnostic and therapeutic devices must be compared; and evaluates the status of jaw tracking for the diagnosis of TMD. This review and evaluation led to the conclusion that, at the present time, the claim that jaw-tracking devices have a diagnostic value for TMD is not well supported by the scientific evidence.

Analysis of jaw movements and masticatory muscle activity.

This paper describes software developed to analyze the temporal and spatial aspects of jaw movements, the speed, direction and magnitude of these movements in three dimensions, and the associated electromyograms (EMGs) of the masticatory muscles. Data from a subject chewing gum illustrates the software application. Manipulations of the stored digitized data are described. Temporal aspects of each chewing cycle are defined by specified delimiters for the beginning and ending of jaw opening and closing; spatial aspects are quantified by measurements derived from movement trajectories; and peak and mean velocities are derived from the velocity profiles. EMGs are digitized, rectified, averaged and referenced to jaw movement. Onset latencies, burst durations, rise times to peak activity, time of occurrence of peak activity, and amplitudes of peak and mean activities are measured from the EMGs. This detailed kinematic/EMG analysis provides previously inaccessible information about jaw muscles and the movements they control.

Effects of chewing frequency and bolus hardness on human incisor trajectory and masseter muscle activity.

Nine adults with no orofacial dysfunctions were instructed to chew a standardized piece of soft or hard gum on the right side in time with a metronome set at 46, 100 or 160 beats/min. Jaw movements were recorded with a Myotronics kinesiograph and masseter electromyograms were detected with surface electrodes. The chewing patterns on either gum were not significantly different in any of their spatial or temporal aspects, in mean or peak opening or closing velocities, or in the timing or level of activity in either masseter at any of the three chewing frequencies. These findings suggest that during metronome-paced chewing the change in sensory feedback resulting from a change in gum hardness exerts little or no effect on either the spatial or temporal aspects of masticatory motor output.