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Biomedical subjects

L M Gallo

Publications and source records attributed to L M Gallo.

16 recordsLinked to original sources
PubMed2000

Mandibular helical axis pathways during mastication.

Condylar and incisor trajectories are often used for the study of mandibular movements. Condylar trajectories, however, depend on the location of the reference point and can be interpreted erroneously. In contrast, the helical axis analysis yields an unequivocal description of rigid body kinematics. The aim of this study was to analyze the mandibular helical axis during mastication. Seven subjects without signs and symptoms of craniomandibular disorders and with class I occlusion were recorded by means of the opto-electronic system Jaws-3D during unilateral mastication of bread cubes (2-cm side). The helical axis was computed every 14 ms with a rotation threshold of 1 . Parameters describing its spatial orientation and position relative to the condyles were calculated. The helical axis changed orientation and position more pronouncedly during the closing than during the opening phases of mastication. The orientation varied significantly from beginning to end of closing but not of opening, indicating less fluctuation of the helical axis on opening than on closing. Also, the distance dCP between helical axis and reference condylar point varied more significantly (p < 0.05) on the working than on the balancing side: On the working side, dCP decreased during both opening and closing, whereas on the balancing side, dCP increased only for closing. Furthermore, the helical axis pathway often showed a bowing ventrally to the balancing condyle, indicating that, during closing, the balancing condyle still translated backward while essentially only rotation occurred around the working condyle. Thus, the helical axis changed its position and orientation continuously during mastication.

Adult↗
PubMed2000

Stress-field translation in the healthy human temporomandibular joint.

Movement over the surface of the temporomandibular joint (TMJ) disc produces tractional forces. These forces potentially increase the magnitude of shear stresses and contribute to wear and fatigue of the disc. Theoretically, tractional forces in all synovial joints are the result of frictional forces, due to rubbing of the cartilage surfaces, and plowing forces, due to translation of the stress-field through the cartilage matrix as the joint surface congruency changes during motion. For plowing forces to occur in the TMJ, there must be mediolateral translation of the stress-field as the condyle moves dorsoventrally during jaw function. To test whether mediolateral stress-field translation occurs in the intact TMJ, we measured stress-field position and translation velocities in ten normal individuals during rhythmic jaw opening and closing. Magnetic resonance imaging and jaw tracking were combined to animate the three-dimensional position of the stress-field between the articulating surfaces. This allowed for mediolateral translation velocity measurements of the centroid of the stress-field. The results showed that during jaw opening and closing at 0.5 Hz, the average peak mediolateral translation velocity was 35 +/- 17 mm/sec. When opening and closing increased to 1.0 Hz, the average peak velocity was 40 +/- 19 mm/sec. Theoretical model estimates of the work done during such translation ranged from 6 to 709 mJ between the individual joints studied. The potential clinical importance of this measure is that long-term exposure of the TMJ disc to high work may result in fatigue failure of the TMJ disc.

Adult↗
PubMed2000

Dynamic magnetic resonance imaging technique for the study of the temporomandibular joint.

AIMS: Echo planar imaging (EPI) is an ultrafast magnetic resonance imaging (MRI) technique that can scan a single frame in less than a second. The aim of this study was to use the EPI technique to develop a new dynamic MRI protocol for the temporomandibular joint (TMJ). METHODS: Basic fast-field echo and EPI pulse sequences were used for dynamic studies of the TMJ. The subjects were instructed to perform spontaneous, continuous, slow opening/closing movements without visual or audio feedback. Different scanning parameter settings were explored to optimize the results. RESULTS: With an opening/closing movement of approximately 6 to 7 seconds per cycle, the proposed protocol yielded a good insight into the relative motion between condyle and disc. It was also possible to see the deformation of the disc during movement. CONCLUSION: The EPI technique is a non-invasive technique that can be used for dynamic imaging study of a slow but continuous, uninterrupted jaw movement.

Adult↗
PubMed2000

Individualized oblique-axial magnetic resonance imaging for improved visualization of mediolateral TMJ disc displacement.

AIMS: A new individualized oblique-axial orientation of magnetic resonance imaging scans of the temporomandibular joint (TMJ), corrected to be perpendicular to the tangent of the posterior slope of the articular eminence, has been proposed to improve the representation of the disc. The aim of this study was to evaluate the quality of the images obtained with this new type of scanning plane and to assess the factors that can affect the scans. METHODS: Twenty-nine TMJs were scanned by the use of sagittal, conventional coronal, and individualized oblique-axial scanning planes. On the sagittal images, the angle alpha between the tangent of the posterior slope of the articular eminence and the vertical was measured, and the disc position was evaluated. For both imaging planes, 2 examiners, blind to the scanning techniques, counted the number of conventional coronal and oblique-axial scans in which the disc was visible and in which the medial and lateral disc borders were well demarcated and evaluated the mediolateral disc position. RESULTS: The individualized oblique-axial technique was superior to the conventional coronal technique in depicting the disc and its medial and lateral demarcations (paired t test, P < 0.05). The possibility of correct diagnosis of the mediolateral disc position and the agreement between the observers in this evaluation were better with the oblique-axial technique than with the conventional technique (P < 0.05). This was particularly evident when the disc was anteriorly displaced. CONCLUSION: The individualized oblique-axial scanning planes should be used for a better representation of the disc/condyle complex mediolaterally if the disc is anteriorly displaced.

Adolescent↗
PubMed2000

Reproducibility of temporomandibular joint clicking.

AIMS: To investigate the stability of temporomandibular joint (TMJ) clicking over a 10-day period and the effect of different open/close velocities on sound amplitude and power spectra in a group of subjects with subjectively stable unilateral clicking during the 3 months preceding the recordings. METHODS: Ten volunteers were recorded with a self-developed microcomputer-based system used in a previous study on asymptomatic subjects. The recordings were performed during 4 different sessions at 3 different open/close rates in each session. The subjective sound intensity was measured with a 100-mm visual analog scale (VAS). The VAS scores, the maximum amplitudes, and the power spectra of the signals were tested for statistical differences among the different open/close rates and over the sessions. The reliability of measurements was also calculated. RESULTS: The maximum amplitude and the power spectra of the TMJ clicking varied between subjects in a broad range that differed from those reported for asymptomatic subjects. No statistically significant differences were found within subjects for the subjective VAS scores for the maximum signal amplitudes or for the power spectrum parameters among the open/close rates and over the 4 sessions. For all 3 open/close rates and for the 4 sessions, a good to excellent reliability of measurements was determined, the values of r being mostly over 0.75. CONCLUSION: Within the limits of the experiment, TMJ clicking was subjectively and objectively stable over a period of 10 days. Therefore, the constant subjective perception of sound intensity was supported by the objective measurements.

Adult↗
PubMed1999

Nocturnal masseter EMG activity of healthy subjects in a natural environment.

Facial pain of patients with craniomandibular disorders might be caused by muscle overload. However, the activity of masticatory muscles of healthy individuals is still unknown. The aim of this study was therefore a first attempt to clarify this question by recording the masseter muscle activity of healthy subjects during sleep by means of portable recorders. The study was performed on 21 healthy subjects selected after telephone and questionnaire screenings and clinical examination from among randomly selected inhabitants of Zürich. The masseter EMG was recorded during seven nights in each subject's natural environment with the electrodes in reproducible position. The signal was analyzed for number, amplitude, and duration of contraction periods defined as signal portions above a threshold which could contain sub-threshold signal portions shorter than the standby time of 5 sec. The signal amplitude was expressed in percent of the amplitude recorded during maximum voluntary clenches (%MVC). An average of 71.9 +/- 28.7 contraction episodes per night (men, 74.7 +/- 30.1; women, 65.0 +/- 23.8; p = 0.043), i.e., of 10.5 +/- 3.8 per hour (men, 11.0 +/- 4.0; women, 9.3 +/- 3.0; p = 0.005), was found. The average mean amplitude was 26.2 +/- 6.4% MVC (men, 27.0 +/- 6.8; women, 24.4 +/- 4.5; p = 0.009). The duration of the episodes had a mode of 0.5 sec, and the group mean of the integral of the amplitude over time was 123.7 +/- 157.9% MVC (men, 138.9 +/- 184.0; women, 85.9 +/- 28.2; p = 0.005). Healthy subjects showed intermittent periods of masseter activity during sleep which, on average, were of rather low intensity and short duration.

Adult↗
PubMed1998

Automatic on-line one-channel recognition of masseter activity.

The etiology of myoarthropathies of the masticatory system (MAP) is not fully understood. For the hypothetical association between the myogenous pain of MAP patients and masticatory muscle overuse to be proved, functional and parafunctional behavior of the masticatory muscles should be analyzed in normal and diseased subjects. The aim of this study was to test on-line the validity and reliability of an algorithm, applied to the electromyographic signal, to recognize various oral activities. The surface electromyogram of the masseter muscle was recorded in 12 subjects (seven females and five males, from 18 to 32 years old) who performed a series of functional and parafunctional activities (chewing soft food, chewing hard food, swallowing, laughing, speaking, and tooth grinding and clenching), as well as no activity. During the computer training phase, intra-individual classification functions of a multivariate discriminant analysis were calculated while each subject performed the described activities. During the test phase, each subject repeated the same activities, and the computer continuously classified them on-line. The percentage of correctly recognized activities was calculated for each activity and for each subject. No activity, chewing hard food, swallowing, laughing, grinding, and clenching were recognized correctly > 99% of the time. Chewing soft food was recognized correctly 97% and speaking 86% of the time. The sensitivity values for the recognition rates of the complete oral activities were, with one exception, > 0.82; the specificity values were > 0.95, and the kappa-values > 0.80. These results show that the algorithm had high sensitivity, specificity, and reliability in the classification of different oral activities under laboratory conditions.

Adolescent↗
PubMed1997

Reliability of scoring EMG orofacial events: polysomnography compared with ambulatory recordings.

The study of sleep bruxism is usually based on clinical history, signs and symptoms. The recording of electromyographic signals with either ambulatory portable home recorders or with polysomnographic techniques in the laboratory environment allows collection of objective data. The present study showed a 100% agreement with clinical evaluation in the recognition of bruxism episodes from the masseter electromyogram recorded with portable recorders and using the polysomnographic technique. On the contrary, scorers had difficulties in discriminating between different types of episodes (phasic, tonic and mixed), the between-scorers agreement varied between 62% and 63% and the kappa-values between 0.43 and 0.33. The ideal time base at which electromyographic signals should be integrated to allow for a good discrimination of bruxism patterns is 0.06 s. The results indicate that portable electromyography recorders are a valuable complement to polysomnographic recordings of orofacial motor activities as they provide a very good recognition rate with adequate time base data collection.

Adult↗
PubMed1997

Description of mandibular finite helical axis pathways in asymptomatic subjects.

Despite wide use of systems to record jaw motion with six degrees of freedom, most studies have analyzed only the movement of a single mandibular point. The finite helical axis (FHA) is a mathematical model which can be used to describe comprehensively the movements of a rigid body. The aim of this investigation was to describe the FHA of the mandible during habitual jaw movements. Thirty subjects (13 females, 17 males; mean age, 26 years; range, 18 to 34 years) without myoarthropathies of the masticatory system participated in the study. Opening and closing movements, performed at 1-Hz frequency, were recorded with the optoelectronic system Jaws-3D. Three opening and closing movements were recorded from the right side and three from the left side of the jaw. The movement data were low-pass-filtered for noise reduction prior to the computation of the finite helical axis by means of a software program developed in our laboratory. The following parameters were calculated: the rotation of the FHA, its spatial orientation, and the translation along it, as well as its position and distance relative to an intracondylar point. In addition, methodological errors of the model were calculated. During opening and closing, the group mean FHA rotation was 24.3 degrees +/- 4.2 degrees. The group mean of the maximum total translation along the FHA was 0.9 +/- 0.7 mm. The group mean distance between the FHA and the intracondylar point was 48.9 +/- 9.9 mm. The FHA pathways were smooth and varied between individuals. Furthermore, the finite helical axes were never localized within the condyle, and often were located outside of the mandible. The analysis of the FHA pathways yields more information on whole mandibular movements than simply the movements of a single condylar point.

Adolescent↗
PubMed1995

Activity recognition in long-term electromyograms.

Long-term electromyography with portable recorders allows the study of muscle activity in the natural environment to investigate whether muscle overuse or oral habits may contribute to initiate or perpetuate a myoarthropathy of the masticatory system. At present, little is known about the behaviour of masticatory muscles over long time periods. The aim of this preliminary study was to define parameters which allow the automatic recognition of different types of oral activities from the electromyogram form. A programme with functional and parafunctional activities was performed by four volunteers (total of 333 functional and 82 parafunctional recordings). Electromyograms of the masseter and temporal muscles were recorded by means of a self-developed portable intelligent solid state recorder. Signal mean level (mw) and dynamics (dw) within a sliding window were determined. Temporal muscle recordings allowed better discrimination between function and simulated parafunction. The average of mw for clenching was 51.4 +/- 3.5% and for tooth grinding 21.2 +/- 2% of the peak electromyogram value at maximum voluntary clench. At 0.96 s sliding window duration, clenching, tooth grinding and chewing signals had maximum separation, using dw/mw as parameters (average: 0.16 +/- 0.01 for clenching, 0.39 +/- 0.01 for teeth grinding and 0.88 +/- 0.01 for chewing).

Adult↗
PubMed1995

A new method for three-dimensional reconstruction and animation of the temporomandibular joint.

The aim of this project was to develop a new method for the three-dimensional reconstruction and animation of the temporomandibular joint (TMJ). Magnetic resonance (MR) tomograms of the TMJ were combined, using an extraorally placed reference system, with jaw motion data, recorded with six degrees of freedom, by means of the opto-electronic tracking system Jaws-3D. The three-dimensional reconstruction of the TMJ was calculated and animated on a graphics workstation by means of kinematic transformations. A subject without any past or present history of myoarthropathies of the masticatory system, performed jaw opening and closing and chewed chewing gum. The animation provided a three-dimensional visualisation of the movements of the entire condyle within the fossa. The condyle-fossa distance was computed for every condylar point and represented by shading the surface of the condyle with pseudo-colours. The position of the minimum distance between condyle and fossa was calculated and displayed in a plane graph representing the condylar surface.

Humans↗
PubMed1994

Precision of the jaw tracking system JAWS-3D.

The purpose of this study was to measure, under laboratory conditions, the noise level of the optoelectronic jaw-tracking system JAWS-3D, which records the movement of the whole mandible from extraorally placed landmarks. Also, an assessment was made of its accuracy in measuring positions, angles, and velocities. The results showed that the accuracy of JAWS-3D decreased when the distance between the recorded point and the extraoral landmarks increased. The path of a point near to the landmarks was estimated with an error of 0.11%, whereas the error increased to 1.33% when the point was far from the landmarks. The maximum error in angle computation was 0.7 degrees. The velocities calculated by JAWS-3D corresponded closely to the actual ones: mean error of 3 mm/s for velocities up to 80 mm/s. Thereafter, the error increased to reach 26 mm/s at a speed of 210 mm/s.

Artifacts↗
PubMed1993

Power spectral analysis of temporomandibular joint sounds in asymptomatic subjects.

Very little has been done to quantify temporomandibular joint (TMJ) sound amplitudes and background noise and to determine the spectrum from healthy TMJs. Thus, the aim of this study was to record acoustically the sounds emitted by healthy TMJs with and without mandibular movements, for determination of baseline spectra. TMJ sounds were recorded bilaterally from 40 subjects with healthy joints by means of a self-developed recording system using miniature capacitor microphones inserted into the earpieces of a medical stethoscope placed in the meatus of the auditory canal. The recordings were performed without mandibular movements and during three consecutive opening and closing movements. The signals were high-pass-filtered at 50 Hz, low-pass-filtered at 2 kHz, and analyzed by fast Fourier transform computation on a 1024-point window (fs = 5 kHz). The linearly weighted average baseline spectrum recorded without motion showed maximum values of 31 dBSPL (sound pressure level) with a standard error of +2 to -3 dB. The linearly weighted average movement spectrum had a peak of 66 dBSPL at 156 Hz and decreased almost linearly by about 40 dB/decade to 25 dBSPL at 2000 Hz with a standard error of +/- 2 dB. Thus, the TMJ sound spectrum of mandibular movements in asymptomatic subjects differed at low frequencies by up to 35 dB from the baseline spectrum in absence of motion.

Adolescent↗
PubMed1992

Long-term results of varicocelectomy.

Between 1983 and 1985, 257 infertile men were examined for any present varicocele by means of the Doppler sonography, telethermography and palpation. Based on these findings, the spermiogram and the infertility history, high ligation of the spermatic vein was indicated in 89 patients with varicocele and a median duration of infertility of 36 months (6-88 months). Postoperative sperm examinations have shown a significant improvement in sperm count and morphology, but not in motility. The most significant drop was observed in germ cell concentration from 1.68 to 1.06 mio/ml (p less than 0.025 Wilcoxon signed rank sum test). The follow-up examination 6 years after the beginning of the study has shown that only 56 out of the 89 patients underwent surgery, whereas 33 patients refrained from it. Pregnancy rates were 42% (23 out of 55, 1 patient lost to follow-up) in the operated group and 45% (14 out of 31, 2 patients lost to follow-up) in the nonoperated group. The comparison of the two graphs showing pregnancy incidence clearly demonstrates that pregnancies in the nonoperated group occur earlier than in the operated group; it has to be noted, however, that several patients only refrained from being operated on because pregnancy had occurred before surgery was planned. On the one hand, our study confirms other authors' results, i.e. that pregnancy rates in the nonoperated group are relatively high despite present varicocele. On the other hand, the operated group achieved practically the same high pregnancy rate when monitored over a longer period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗