Paradigmatic shifts in occlusion and temporomandibular disorders

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72325/1/j.1365-2842.2001.00658.x.pd

Frequency analysis of human jaw tremor at rest

It is not known whether rest position is controlled actively by a low degree of muscular activity or passively by muscular and tissue visco-elasticity. The frequency analysis of the jaw tremor at rest was studied to determine if it could be useful for the study of rest position. Jaw tremor was recorded in three different head positions of normal subjects by two accelerometers fixed to the upper and lower premolars. The acceleration signals were low-pass filtered, digitized and analysed by computer. A Fast Fourier Transform algorithm was used to determine spectral density. Electromyograms of the right and left anterior temporal and masseter muscles and an electrocardiogram were recorded with surface electrodes, and the data correlated with jaw tremor. The lower jaw oscillated at the same frequency as the head, and the tremor was a low-frequency narrow-band process. Head deflection produced changes in the power spectral density of the tremor. A time correlation between the shape of the acceleration raw data and the heart beat was present in every subject. However, frequency content and power spectral density of the jaw tremor at rest may be determined also by the degree of muscular activity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23748/1/0000721.pd

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 < 0.01) between the two diagnostic parameters of TMJ-muscle-pain dysfunction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67021/2/10.1177_00220345770560031001.pd

Ossification in adult rat mandibular coyndyle--SEM of chondroclasia

The morphology of the mineralized component at the osteochondral junction was studied in the mandibular condyle of 264-day-old rats. Specimens were rendered anorganic in NaOCl, cut open with a sculpel, and the resulting surfaces examined in a scanning electron microscope. The extent of the mineralized cartilage plate and its relationship to invading vascular channels were visualized. Areas of resorption of calcified cartilage were identified and compared to areas of bone resorption. A likely sequence of events was reconstructed from the exposed internal surfaces: from initial chondroclasia in individual lacunae to extensive resorption of the cartilage plate; and from initial deposition of bone over the resorbed calcified cartilage cores to the organization of osteocyte lacunae and bony trabecule. The mandibular condyle has not been examined in this way previously. Possible cellular mechanisms suggested by other studies to be operating at the osteogenic front are discussed in the light of the results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24493/1/0000769.pd

Scanning electron microscopy of mineralized cartilage in rat mandibular condyle

The pattern of mineralization was studied in the mandibular condyle of the young adult rat. Specimens were rendered anorganic in NaOCl and examined in a scanning electron microscope. A mineralized cartilage front was found to persist on the articular aspect of the condyle. The surface is characterized by closely approximating chondrocyte lacunae enclosed to different degrees within the mineralized front. The mineralized component itself is calcospheritic; larger calcospherites forming the inner concave wall and smaller calcospherites forming the outer convex wall. The calcospherites are comprised of irregular crystalline plates radiating from the center of the mass. The bony surface of the ramus immediately beneath the condyle is typified by Howship's lacunae alternating with areas of forming bone indicating intense remodeling activity. The mandibular condyle has not been examined in this way before. The information is relevant to consideration of growth and development, functional adaptation, physiological aging, and pathological change.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23178/1/0000105.pd

A quantitative measure of mandibular joint dysfunction: Phase plane modelling of jaw movement in man

Jaw movement during the open-close-clench cycle was recorded using a Hall-effect generator and a small permanent magnet affixed to opposing incisor teeth. Computer programs provided graphic display of jaw-closing velocity as a function of jaw position (the phase plane) and determined the error between the experimental data and a mathematical model. A large error indicated dysfunction and predicted successful treatment by accepted occlusal therapy; a small error indicated normal function or predicted unsuccessful occlusal treatment. These observations suggest that phase plane modelling provides a quantitative measure of joint dysfunction that may be used in monitoring treatment progress and in separating clinically diagnosed dysfunction into two categories--one which responds to occlusal therapy, and one which does not.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21920/1/0000327.pd

The influence of mechanical input parameters on the duration of the mandibular joint electromyographic silent period in man

The duration of the electromyographic silent period following a tap to the menton has been reported to be clinically useful in the diagnosis of mandibular joint dysfunction but not the influence of details of the tap. Using a solenoid-driven mechanical tapper, the following were investigated: in patients with joint dysfunction, effect on single muscles and position of the tap in a sequence of taps, in normal subjects, force of the tap, degree of opening of the jaw, angle of tap, and the biting force; all on the duration of the resulting silent period. No significant changes could be ascribed to any of these variables. The introduction between the teeth of wooden shims or a bite-force transducer were the only factors to change the duration. The dysfunction group had significantly longer silent periods than the normal group. It is concluded that, provided nothing is introduced between the teeth, the input parameters investigated do not influence the duration of the silent period.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23065/1/0000638.pd

Calibration of six-channel intraoral occlusal forces transmitters : final report

http://deepblue.lib.umich.edu/bitstream/2027.42/3302/5/bab0391.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/3302/4/bab0391.0001.001.tx

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.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67705/2/10.1177_00220345790580120401.pd