The variability of EMG silent periods in TMJ patients

The variability of the EMG silent period in jaw closing muscles of TMJ dysfunction patients was examined. Considerable within-subject variability was found in the duration of the silent period. This variability increased with symptom severity. The authors recommend that multiple measurements be averaged to obtain a more accurate estimate of the silent period duration.     

EMG silent periods in immediate complete denture patients: a longitudinal study.

Jaw muscle silent periods in response to chin taps were recorded from immediate complete denture patients before extraction of a residual anterior dentition, after insertion of the dentures, and three and six months after insertion. After three months' use of the dentures, the mean EMG silent period duration was significantly increased compared to the pre-extraction stage.     

The silent period in the masseter muscle of patients with TMJ dysfunction.

The silent period (SP) following a jaw jerk elicited during sustained contraction in the masseter muscles has been studied in two groups of subjects, one with and one without, acute and distinct symptoms of TMJ dysfunction. The subjects with acute TMJ dysfunction symptoms showed significantly shorter latency and longer duration of the silent period and the period of their depressed activity (DA) was also significantly longer than in the group without TMJ dysfunction. The duration of the SP of both muscles was symmetrical in about 60% of subjects in each group. This study validates that the duration of the silent period may be a useful diagnostic tool of clinical interest.     

TMJ fractures in children: clinical management and follow-up

The mandible is the facial structure that is the most affected by trauma and the most common fracture site is the condyle. New perspectives for this problem are due to the fact that often TMJ fractures in children are undiagnosed and consequently untreated. This becomes evident when growth disturbances show up a year or two later. These types of trauma must be focused not only as a cause of direct damage to osseous structures, but also of future disturbances of the dentofacial development. Three cases of particular significance for the requested therapeutic approach are reported.     

Clinical and radiological follow-up results of patients with untreated TMJ closed lock

The purpose of this study was to compare clinical and radiological findings of untreated closed lock patients at least 22 months after initial diagnosis. Ten patients with closed lock in at least one joint who had received no treatment were included in the study. Clinically maximum mouth opening, joint pain and joint sounds were recorded. Radiologically position of the disc, disc morphology, bone degeneration and presence of fluid were determined on magnetic resonance imaging. Clinical and radiological examinations were repeated 2-5 years after initial examinations. Results were statistically compared using either the non-parametric McNemar test or the Wilcoxon signed-rank test. There were significant improvements in both mouth opening capacity and prevalence of joint pain, while no significant change in radiological examination. The results of this study suggested that closed lock patients undergo active adaptation in clinical symptoms.     

TMJ Concepts/Techmedica custom-made TMJ total joint prosthesis: 5-year follow-up study

This prospective study evaluated the 5 to 8 year subjective and objective results of 42 consecutive patients who had TMJ reconstruction using the TMJ Concepts/Techmedica custom made total joint prosthesis. Criteria for use of the prosthesis included the following TMJ conditions: (1) multiply operated, (2) previous alloplastic implants, (3) osteoarthritis, (4) inflammatory or resorptive arthritis, (5) connective tissue or autoimmune disease, (6) ankylosis, and (7) absent or deformed structures. Thirty-eight of 42 patients (90%) with 69 TMJs reconstructed using the TMJ Concepts/Techmedica total joint prosthesis had appropriate data for inclusion in the study. The average age at surgery was 36 years and average follow-up was 73.5 months. The entire group and three subgroups were objectively evaluated for incisal opening, lateral excursions, and occlusal stability, while subjectively assessed for pain and jaw function. Paired t-test and comparison analyses were used to assess outcomes. For the group of 38 patients, there was statistically significant improvement in incisal opening (P=0.001), jaw function (P=0.001), and pain level (P=0.0001). Lateral excursion movements significantly decreased (P=0.04). The occlusion remained stable in all cases. Complications occurred in six patients. Comparison analysis of the three groups demonstrated significantly better outcomes for patients with fewer previous TMJ surgeries and without exposure to Proplast-Teflon or Silastic TMJ implants. This study demonstrated that the TMJ Concepts/Techmedica total joint prosthesis is a viable technique for TMJ reconstruction as a primary procedure and for patients with previous multiple TMJ surgeries and mutilated anatomy of the TMJ.     

Tibond钛瓷冠修复的三年临床观察

目的：观察钛瓷冠修复的临床效果。方法：1999年至2000年,为我院口腔修复门诊病人56例制作钛金属烤瓷单冠109颗,修复完成后6个月、1年和3年复诊,检查钛瓷冠边缘密合性、固位、颜色、牙龈健康状况及冠的完整性。结果：参加复查的多数修复体边缘密合,固位良好,颜色协调,牙龈健康,牙冠无破损,患者满意。结论：钛瓷冠可作为永久修复体应用于临床。     

Jaw muscle silent periods by tooth tap and chin tap

Electromyographic silent periods from jaw closing muscles were elicited during a clench by tapping on the chin and on selected teeth both in asymptomatic subjects and in subjects reporting symptoms of temporomandibular joint dysfunction. The mean duration in response to a chin tap was significantly shorter in the asymptomatic group than in the dysfunction group. No significant differences in mean duration elicited by tooth taps were found between groups. Other comparisons of mean durations such as among muscles, among teeth, or between chin taps and tooth taps failed to achieve statistical significance.     

TMJ diagnosis and treatment in a multidisciplinary environment--a follow-up study

New modalities--TMJ direct parasagittal CT and MRI scans and arthroscopic visualization and surgery--along with psychological and other health professional support, are changing the approach to clinical orthodontic practice. This report presents an update on clinical experience over a period of time, with emphasis on orthodontics, psychology, and arthroscopic surgery.     

Endodontic retreatment: explaining success rates and illustrated cases

Endodontic retreatment is less successful than conventional root treatment. Factors governing this include difficulty in accessing the root canal system in retreatment cases, problems in negotiating a highly resistant microflora and unfavourable anatomy. However, despite these mitigating factors success is still a realistic goal in the majority of cases.     

Jaw muscle silent periods before and after rapid palatal expansion.

1. The electromyographic silent period was observed in jaw-closing muscles during a maximal clench following a tap to the mandibular symphysis in eight subjects before and after rapid palatal expansion. 2. No differences in mean silent period duration were observed among the three jaw-closing muscles examined. 3. A large (r = 0.96) and statistically significant (p less than 0.01) correlation coefficient between two sets of silent period durations at one session indicates that these measurements are repeatable and reliable. 4. The mean silent period duration for the eight patients with malocclusions was 33.5 msec. prior to rapid palatal expansion and 51.2 msec. after the completion of palatal expansion. The difference was statistically significant (p less than 0.01) and represents a 61 percent increase. 5. Patients with symptoms of TMJ dysfunction are not the only group showing a prolonged silent period duration.     

儿童颞下颌关节骨关节病的临床X线特征及追踪研究

目的　探讨儿童颞下颌关节骨关节病的临床、X线特征及预后等。方法　收集 1 6岁以下因颞下颌关节紊乱症状就诊儿童 348例 ,均无全身系统性疾病 ,血清学检查正常。结合临床及X线检查 ,诊断为儿童颞下颌关节骨关节病 40例 ,对其中 2 0例进行追踪观察。结果　儿童颞下颌关节骨关节病多见于女性 ,关节弹响为最常见症状 ,髁状突骨破坏为最常见的X线表现。结论　儿童颞下颌关节骨关节病的自然发展过程中临床症状及X线表现均可以加重 ,应引起临床重视     

Electromyographic silent periods and jaw motion parameters: quantitative measures of temporomandibular joint dysfunction.

The purpose of this research was to compare, in the subjects, the duration of the EMG silent period with jaw motion error. The results indicate that both jaw motion error and silent period duration are large in patients with TMJ-muscle-pain dysfunction, both are small in normal subjects, and both are small in successfully treated patients. There is a statistically significant correlation (r=0.91; P less than 0.01) between the two diagnostic parameters of TMJ-muscle-pain dysfunction.     

Loci and characteristics of EMG silent periods during masticatory mandibular movements in rats

Frontal plane mandibular movements and the associated superficial masseter EMG signals of six 39-day-old rats were simultaneously recorded and digitized at a rate of 1 kHz by the optoelectronic method in order to investigate the loci and attributes of masseteric silent periods during mastication of hard (pellets) and soft (slurry) food items. The marked silent periods, defined as cessations of EMG activity during the slow-close (SC) phase of single chewing cycles, were analyzed for their (1) onset and offset durations relative to physiological centric occlusion (PCO), (2) frontal vertical (FV) and frontal horizontal (FH) loci relative to PCO, and (3) FV and FH velocities and accelerations of masticatory mandibular movements in relation to PCO. The start (SSP) and end (ESP) of silent period loci relative to PCO moved superiorly as sequences of pellet mastication progressed. All silent period attributes during slurry consumption were significantly different (p less than or equal to 0.01) from pellet attributes: Slurry SSP and ESP loci were closer to PCO than were pellet loci; durations of silent period loci during pellet mastication were more variable than were slurry durations. FV distance and velocity values for pellets were greater than with pellets. Although FV velocities during both pellet and slurry mastication decreased at ESP relative to SSP values, their FH velocities at ESP actually increased relative to SSP velocities. Loci attributes of EMG silent periods appeared largely dependent on the consistency of the food item being masticated.