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At least 73 records · Page 4Linked to original sources
PubMed2003

Accuracy and reliability of torque wrenches used for halo application in children.

BACKGROUND: Halo ring and vest application in children requires torque wrenches capable of delivering a spectrum of torque values ranging from 0.11 to 0.68 N-m (1 to 6 in-lb). Published evaluations of torque wrenches commonly used in adults have shown that the measured torque values were within 10% of the target torque in only 64% of trials. The objective of the present study was to evaluate the accuracy, reliability, and interobserver variability of halo wrenches capable of applying the lower torque levels commonly used in children. METHODS: Torque wrenches from four distributors (Bremer, Jerome Medical, Mountz, and PMT) were tested with use of a calibrated torque-meter. Five wrenches of each type were tested by a single observer, with fifty trials performed at six different torque settings (0.11, 0.23, 0.34, 0.45, 0.57, and 0.68 N-m). One wrench of each type was then tested by two additional observers at a torque setting of 0.34 N-m, with each observer performing fifty trials per wrench. RESULTS: The measured torque value was within 10% of the target value in 69.2% of the 6400 trials, including 50.7% of the trials performed with the PMT wrench, 51.8% of those performed with the Bremer wrench, 84.5% of those performed with the Mountz wrench, and 90% of those performed with the Jerome wrench. Significant variability (p < 0.05) was found between at least two, and as many as five, wrenches of the same variety at each of three torque settings used for comparison (0.23, 0.45, and 0.68 N-m). Significant interobserver variability (p < 0.05) was found between at least two observers during testing of the Jerome and Mountz wrenches, but no significant differences were shown between observers during testing of the PMT and Bremer wrenches. CONCLUSIONS: The Jerome and Mountz wrenches are more accurate and reliable at low torque settings than the PMT and Bremer wrenches are. Variability among different wrenches from the same manufacturer may be seen with any of the wrenches studied.

Child↗
PubMed2002

Torque capacity of metal and plastic brackets with reference to materials, application, technology and biomechanics.

AIM: The aim of the present study was to investigate slot deformation and the equivalent torque capacity of plastic brackets in comparison with those of a metal bracket in vitro and to simulate them under clinical conditions. MATERIAL AND METHOD: For this purpose the expansion characteristics of the brackets and their resistance to extraoral mechanical loading were compared in in-vitro activating experiments. In a further investigation, the labial crown torque of an upper central incisor was measured in a simulated intraoral clinical situation, using the Orthodontic Measuring and Simulation System (OMSS). Four types of bracket manufactured by Forstadent, Pforzheim, Germany, were tested: the plastic brackets Aesthetik-Line and Brillant, the latter from a previous series (Brillant-old) and from a modified series (Brillant-new), and the metal bracket MINI-MONO. For testing purposes the brackets were torqued with 0.016" x 0.022" (0.41 x 0.56 mm) and 0.018" x 0.022" (0.46 x 0.56 mm) ideal steel archwires (Remanium, Dentaurum, Ispringen, Germany). RESULTS: In the activating experiments, significantly higher torque losses and lower torquing moments were registered with both rectangular archwires with the plastic brackets than with the metal bracket. In the simulation tests, significantly higher torquing moments were registered with the metal bracket than with the plastic brackets. The OMSS model approximates the clinical situation, with the torque loss being notably higher than in the in-vitro activating experiments. This is due to the adjacent teeth giving the archwire additional play. In addition, the torquing process of the rectangular wire may deform the archwire, resulting in subsidiary forces. CONCLUSION: On the basis of the present results, the Brillant and Aesthetik-Line plastic brackets and the MINI-MONO metal bracket can be recommended for torquing. In view of the high torque losses, however, the torques programmed in the straight wire technique must be seen as questionable. It would be helpful to the practitioner if data were provided by the manufacturer on the flexing to be expected in plastic brackets, which has to be offset by additional torque or the possible renunciation of bracket torque.

Biomechanical Phenomena↗
PubMed1996

Effects of age on rapid ankle torque development.

BACKGROUND: When balance is disturbed, often only fractions of a second are available in which to make the initial responses needed for its restoration. Abilities to develop joint torques rapidly may be critical to such responses. We undertook this study to quantify age effects among healthy adults in abilities to develop ankle joint torques rapidly. METHODS: Ankle dorsiflexion (DF) and plantarflexion (PF) torque development during rapid isometric and during isokinetic (30, 60, 120, 180, and 240 deg/sec) exertions was assessed in 24 healthy young (mean age 23 years) and 24 healthy old adults (mean age 72 years). The effects of age, gender, and torque direction on the times needed to reach given torque magnitudes, maximum rates of isometric torque development (MRTD), and maximum isokinetic torques were examined. RESULTS: The old adults required substantially more time to reach given torque magnitudes than the young adults. For example, the young and old females needed approximately 236 and 337 msec to develop 15 Nm of DF torque, of which 141 and 164 msec were reaction times. Isometric MRTD were 25 to 36% lower in the old than in the young adults. The age declines in isometric torque development time were associated with losses in maximum isometric strength. Maximum isokinetic torques developed by the old were 20 to 40% lower than those of young adults. The percent losses in isokinetic torques with age were independent of joint angular velocity for PF, but increased with velocity for DF. CONCLUSIONS: We found substantial age declines in abilities of healthy old adults to rapidly develop ankle joint torques. The capacities of even healthy old adults to recover balance or to carry out other time-critical actions that require moderate-to-substantial strengths may be considerably degraded by these declines.

Adult↗
PubMed1979

Foot-pounds of torque of the normal knee and the rehabilitated postmeniscectomy knee.

Foot-pounds of torque of the knee flexors and knee extensors of eight rehabilitated patients who had had meniscectomies were obtained isometrically and at 60 and 210 degrees per second by use of an isokinetic apparatus. Our purpose was to test the null hypothesis that no significant difference in torque would be manifested between the rehabilitated postmeniscectomy knee and the normal knee. Mean torque developed by the rehabilitated postoperative knee was 10 to 12 percent less than the mean torque developed by the normal knee. We found a significant difference between means of torque of the normal knee and the rehabilitated knee for isometric flexion, rapid dynamic flexion, and rapid dynamic extension. Means of torque of knee extension for the three types of contraction for both knees of the subjects demonstrated similar patterns in which torque developed isometrically was greater than torque developed by slow dynamic tension, which in turn was greater than torque developed by rapid dynamic contraction. Means of torque of knee flexion for the three types of contraction for both knees of the subjects created patterns in which torque developed isometrically was essentially equal to torque developed by slow dynamic tension, and both these measurements exceeded torque developed by rapid dynamic contractions. Overall, the results suggest that physical therapists need to use rehabilitative techniques that promote muscular power and muscular endurance in addition to muscular strength and that more attention needs to be directed to the rehabilitation of knee flexors.

Adolescent↗
PubMed1997

Tangential torque effects on the control of grip forces when holding objects with a precision grip.

When we manipulate small objects, our fingertips are generally subjected to tangential torques about the axis normal to the grasp surface in addition to linear forces tangential to the grasp surface. Tangential torques can arise because the normal force is distributed across the contact area rather than focused at a point. We investigated the effects of tangential torques and tangential forces on the minimum normal forces required to prevent slips (slip force) and on the normal forces actually employed by subjects to hold an object in a stationary position with the use of the tips of the index finger and thumb. By changing the location of the object's center of gravity in relation to the grasp surface, various levels of tangential torque (0-50 N x mm) were created while the subject counteracted object rotation. Tangential force (0-3.4 N) was varied by changing the weight of the object. The flat grasp surfaces were covered with rayon, suede, or sandpaper, providing differences in friction in relation to the skin. Under zero tangential force, both the employed normal force and the slip force increased in proportion to tangential torque with a slope that reflected the current frictional condition. Likewise, with pure tangential force, these forces increased in proportion to tangential force. The effects of combined tangential torques and tangential forces on the slip force were primarily additive, but there was a significant interaction of these variables. Specifically, the increase in slip force for a given increment in torque decreases as a function of tangential force. A mathematical model was developed that successfully predicted slip force from tangential torque, tangential force, and an estimate of coefficient of static friction in the digit-surface interface. The effects of combined tangential torques and forces on the employed normal force showed the same pattern as the effects on the slip force. The safety margin against frictional slips, measured as the difference between the employed normal force and the slip force, was relatively small and constant across all tangential force and torque levels except at small torques (< 10 N x mm). There was no difference in safety margin between the digits. In conclusion, tangential torque strongly influences the normal force required for grasp stability. When controlling normal force, people take into account, in a precise fashion, the slip force reflecting both tangential force and tangential torque and their interaction as well as the current frictional condition in the object-digit interface.

Adult↗
PubMed1988

Tibial torque generation in a flexed weight-bearing stance.

Internal and external torque generated about the long axis of the lower extremity was measured in 18 male subjects who were instructed to twist with maximal effort against a fixed footplate containing an instrumented torque cell. Mean torque values ranged from 30 to 71 newton meters (Nm) depending upon the test conditions. Torques recorded during the flexed single-leg stance were 19% to 49% higher than those measured while seated. Values at 45 degrees of knee flexion were 11% to 16% greater than those at 20 degrees. Torques generated while wearing a ski boot were 8% to 11% greater than those recorded in an athletic shoe. When movement of the pelvis and upper torso was allowed, torque values were 17% to 49% higher than those recorded when the hips and shoulders were restrained which allowed only lower leg musculature to act in an isolated fashion. There were no differences between internal versus external generated torques when the hips and torso were restrained. When the hips and shoulders were unrestrained, internal torque was 12% greater than external torque. There were no strong correlations between generated torque and body weight or height. These generated torque values suggest that if ski bindings are set to American Society for Testing and Materials (ASTM) standards for twist-release torque, then upper torso and pelvic movement in conjunction with tensed knee musculature (i.e., a "locked knee") may be necessary to accomplish binding release. Use of the lower leg musculature alone (i.e., ankle twist) may not generate sufficient torque for release.

Adult↗
PubMed2003

Matching different levels of isometric torque in elbow flexor muscles after eccentric exercise.

Human subjects generated a specified level of isometric torque with elbow flexor muscles of one arm, the reference arm, under visual feedback. They were then asked to generate what they perceived to be the same level, with the other arm, the indicator, but with no visual feedback. A number of torque levels, between 2% and 30% of maximum were used in the matching trials. Elbow flexors of one arm were then exercised eccentrically on a dynamometer. Immediately after the exercise, there was a large (40%) drop in maximum voluntary torque, as well as some soreness and swelling 24 h later, indicative of muscle damage. When the torque-matching experiment was repeated after the indicator arm had been exercised, the indicator signalled torque levels significantly below the reference level (P<0.05). When the reference arm was exercised, errors were in the opposite direction. Over the 4 days of testing post-exercise, errors became less as torque levels returned to normal. When errors were expressed in terms of maximum torque post-exercise, they were significantly reduced. This suggested that subjects were using as a matching cue the perceived effort required to generate a given level of torque rather than the level of torque itself. Persisting matching errors, from 24 h onwards after the eccentric contractions, were proposed to include a component attributable to the muscle soreness. Changes in electromyogram recorded after eccentric exercise were consistent with the effort-matching hypothesis. The muscle's torque-angle relationship was used to estimate matching ability in the absence of fatigue. One forearm was placed at various angles and its reference torque was matched by the other, the indicator, always at 90 degrees. Again, matching errors were consistent with an interpretation based on a match of effort rather than torque.

Adolescent↗
PubMed2003

Reflex and non-reflex torque responses to stretch of the human knee extensors.

Reflex responses to unexpected stretches are well documented for selected muscles in both animal and human. Moreover, investigations of their possible functional significance have revealed that stretch reflexes can contribute substantially to the overall stiffness of a joint. In the lower extremity only the muscles spanning the human ankle joint have been investigated in the past. This study implemented a unique hydraulic actuator to study the contributions of the knee extensor stretch reflex to the overall knee joint torque. The quadriceps muscles were stretched at various background torques, produced either voluntarily or by electrical stimulation, and thus the purely reflex mediated torque could be calculated. The stretch had a velocity of 67 degrees /s and an amplitude of 20 degrees. A reflex response as measured by electromyography (EMG) was observed in all knee extensors at latencies of 26 - 36 ms. Both phasic and tonic EMG stretch responses increased with increasing background torques. Lines of best fit produced correlation coefficients of 0.59 - 0.78. This study is the first to examine the reflex contribution of the knee extensors to the total torque at background torques of 0 - 90% MVC. The contribution of the reflex mediated torque is initially low and peaked at background torques of 20 - 40% MVC. In terms of the total torque the reflex contributed 16 - 52% across all levels of background torque. It is concluded that during medium background torque levels such as those obtained during walking, the stretch reflex of the quadriceps muscle group contributes substantially to the total torque around the knee joint.

Adult↗
PubMed2004

Passive and active floating torque during swimming.

The purpose of this study was to examine the effect of passive underwater torque on active body angle with the horizontal during front crawl swimming and to assess the effect of body size on passive torque and active body angle. Additionally, the effects of passive torque, body angle and hydrostatic lift on maximal sprinting performance were addressed. Ten boys [aged 11.7 (0.8) years] and 12 male adult [aged 21.4 (3.7) years] swimmers volunteered to participate. Their body angle with the horizontal was measured at maximal velocity, and at two submaximal velocities using an underwater video camera system. Passive torque and hydrostatic lift were measured during an underwater weighing procedure, and the center of mass and center of volume were determined. The results showed that passive torque correlated significantly with the body angle at a velocity 63% of v(max) ( alpha(63) r=-0.57), and that size-normalized passive torque correlated significantly with the alpha(63) and alpha(77) (77% of v(max)) with r=-0.59 and r=-0.54 respectively. Hydrostatic lift correlated with alpha(63) with r=-0.45. The negative correlation coefficients are suggested to be due to the adults having learned to overcome passive torque when swimming at submaximal velocities by correcting their body angle. It is concluded that at higher velocities the passive torque and hydrostatic lift do not influence body angle during swimming. At a velocity of 63% of v(max), hydrostatic lift and passive torque influences body angle. Passive torque and size-normalized passive torque increases with body size. When corrected for body size, hydrostatic lift and passive torque did not influence the maximal sprinting velocity.

Adult↗
PubMed2005

Influence of advanced electromyogram (EMG) amplitude processors on EMG-to-torque estimation during constant-posture, force-varying contractions.

Numerous studies have investigated the relationship between surface electromyogram (EMG) and torque exerted about a joint. Most studies have used conventional EMG amplitude (EMGamp) processing, such as rectification followed by low-pass filtering, to pre-process the EMG before relating it to torque. Recently, advanced EMGamp processors that incorporate signal whitening and multiple-channel combination have been shown to significantly improve EMGamp processing. In this study, we compared the performance of EMGamp-torque estimators with and without these advanced EMGamp processors. Fifteen subjects produced constant-posture, non-fatiguing, force-varying contractions about the elbow while torque and biceps/triceps EMG were recorded. EMGamp was related to torque using a linear FIR model. Both whitening and multiple-channel combination reduced EMG-torque errors and their combination provided an additive benefit. Using a 15th-order linear FIR model, EMG-torque errors with a four-channel, whitened processor averaged 7.3% of maximum voluntary contraction (MVC) (or 78% of variance accounted for). By comparison, the equivalent single-channel, unwhitened (conventional) processor produced an average error of 9.9% of MVC (variance accounted for of 55%). In addition, the study describes the occurrence of spurious peaks in estimated torque when the torque model is created from data with a sampling rate well above the bandwidth of the torque. This problem occurs when the torque data are sampled at the same rate as the EMG data. The problem is corrected by decimating the EMGamp prior to relating it to joint torque, in our case to an effective sampling rate of 40.96 Hz.

Adult↗
PubMed2005

Changes in neuromuscular function after tasks involving control of EMG versus torque feedback of the same duration.

This study was designed to compare alterations in neuromuscular function after two tasks of similar duration involving the control of (1) torque level fixed at 40% maximal voluntary contraction (MVC) torque (torque task) and (2) EMG level when exerting 40% MVC torque on the knee extensor muscles. Ten healthy subjects volunteered to participate in two testing sessions separated by approximately 2 h. Contraction duration for the EMG task was fixed for each subject to the time to task failure of the torque task (104+/-20s). MVC, maximal voluntary activation level, muscle compound action potential (M-wave), peak twitch and potentiated peak doublet were assessed before and immediately after each task using electrical stimulation of the femoral nerve. Average EMG activity of quadriceps muscle increased (p<0.01) during the torque task from 27.7+/-5.4% to 46.2+/-19.3% maximal EMG, whereas torque decreased during the EMG task from 41.5+/-2.9% to 28.9+/-3.8% MVC torque. Alterations in MVC torque (p<0.01) and maximal voluntary activation level (p<0.05) were comparable at termination of the two tasks. Rate of perceived exertion was greater (p<0.05) at the end of the torque task compared to the EMG task. Despite the absence of change in the M-wave for either task, potentiated peak doublet was altered after the torque task (-18+/-14%, p<0.01), whereas there was no change after the EMG task (p>0.05). The absence of peripheral failure at the end of the EMG task could be attributed to (1) a lower intramuscular pressure allowing a lesser accumulation of metabolites and (2) a slower rate of PCr hydrolysis compared to the torque task.

Adult↗
PubMed2001

Deficits in eccentric versus concentric torque in children with spastic cerebral palsy.

PURPOSE: The purposes of this study were to determine whether ambulatory children with spastic cerebral palsy (CP) had abnormal isokinetic eccentric peak torque values at the knee and ankle, and to gain further insights on the influence of spasticity on voluntary force production in this population. METHODS: Twenty-four children with spastic CP (mean = 11.1+/-2.6 yr) and twenty children of comparable age with no neuromotor pathology (mean = 10.3+/-2.6 yr) participated in an isokinetic testing protocol on a Biodex dynamometer that measured eccentric and concentric peak torques of the knee extensors, knee flexors, ankle dorsiflexors, and ankle plantarflexors. Angular velocity of the eccentric trials was 30 degrees x s(-1) and of the concentric trials was 30 degrees x s(-1), 60 degrees x s(-1), and 120 degrees x s(-1). Peak torque values were normalized by body weight and compared across groups by using ANOVA procedures. Eccentric to concentric (E/C) peak torque ratios at 30 degrees x s(-1) were computed for each muscle and compared across groups. The torque values in CP were also expressed as a percent of the mean normalized value of the comparison group and compared across conditions using repeated measures ANOVA (P < 0.05). RESULTS: Children with CP demonstrated decreased eccentric and concentric peak torques for all muscle groups tested. The relative deficit in eccentric torque was less than the concentric torque and the decrement in concentric torque across speeds was greater in CP for all muscle groups except the ankle dorsiflexors. The E/C ratios for the knee extensors and flexors were also greater in CP. CONCLUSIONS: Children with CP have diminished eccentric as well as concentric peak torques at the knee and ankle. The influence of spasticity on voluntary force production can be inferred from the bias toward greater eccentric torque and the greater decrement in concentric torque across speeds in children with spastic CP.

Adolescent↗
PubMed2005

Muscle synergies at the elbow in static and oscillating isometric torque tasks with dual degrees of freedom.

This study's aim was to identify the effect of oscillation of torques in isometric tasks under identical mechanical conditions on the muscle synergies used. It was hypothesized that bi-functional muscles would play a lesser role in torque oscillation, because they would also generate an undesired oscillation. Thus, changes in muscle synergies were expected as a consequence of oscillation in torque generation. The effect of the trajectory of torque generation was investigated in dual-degrees-of-freedom submaximal isometric oscillation torque tasks at the elbow. The torques were flexion-extension and supination-pronation. Oscillation torques were compared with static torque generations at four torque positions during oscillation. Muscle activity was determined with surface electromyography. Compared with the static torque tasks, the oscillation tasks showed an overall increased muscle activity. The oscillation tasks, however, showed similar activity patterns and muscle synergies compared to the static composite tasks. It was found that the motor system is well able to control different orthogonal combinations of slow torque oscillations and constant torques by employing a single oscillating muscle synergy.

Adolescent↗
PubMed1999

Concentric isokinetic torque characteristics of the calf muscles of active women aged 20 to 84 years.

STUDY DESIGN: Descriptive, comparative, and correlational study of nonimpaired, active women in 3 age groups. OBJECTIVES: We described age-related concentric isokinetic torque of plantar flexion (PF) of active women and examined the proposal that PF torque at slow to rapid velocities would be influenced by age-related slower muscle contractile properties. We also examined the relationship of age to passive and active force characteristics of the calf muscle. BACKGROUND: Aging is associated with decreased calf muscle strength, slower muscle contractile properties, and decreased dorsiflexion (DF) range of motion. Clinical methods of measuring these changes in the calf muscles have not been described adequately. METHODS AND MEASURES: 24 younger women (20 to 39 years), 24 middle-aged women (40 to 59 years), and 33 older women (60 to 84 years) performed maximal concentric PF of the right ankle from maximal passive DF at randomly ordered velocities of 30 degrees.s-1, 60 degrees.s-1, 120 degrees.s-1, and 180 degrees.s-1. The peak and mean torques and "angular delay" (degree) from the onset of movement to peak torque were examined using ANOVA. Age was correlated (Pearson product moment r) with the peak and mean torques, "angular delay," velocity at peak torque for 180 degrees.s-1, and the maximal passive DF angle and torque. RESULTS: The peak and mean torques decreased with increasing age and velocities. The angular delay at 180 degrees.s-1 decreased with increasing age. Age was negatively correlated with the peak and mean torques (range, r = -0.60 to -0.73), the "angular delay" at all velocities (range, r = -0.44 to -0.64), the maximal passive DF angle (r = -0.73) and torque (r = -0.60), and with the peak torque velocity at 180 degrees.s-1 (r = -0.29). CONCLUSIONS: The results indicate age-related changes for the concentric isokinetic torque of the calf muscles of active women. The angular delay at 180 degrees.s-1 may show changes influenced by slower muscle contractile properties. Concurrent age-related declines in passive and active calf muscle force characteristics were demonstrated.

Adult↗
PubMedDate not supplied

Removal torque of miniscrews used for orthodontic anchorage--a preliminary report.

PURPOSE: Implant anchors such as miniscrews and miniplates have been loaded immediately for anchorage during orthodontic treatment. The purpose of this study was to measure the removal torque of immediately loaded miniscrews after clinical usage and to determine the possible factors associated with this value. MATERIALS AND METHODS: From 29 patients with malocclusions, 46 miniscrews were removed, and removal torque was measured with a torque gauge. Removal torque values were subjected to statistical analysis for possible association of different clinical characteristics. RESULTS: The mean removal torque value was 1.10 kg x cm, and removal torques for 50% of the implants were greater than 0.89 kg x cm (8.7 N x cm). Removal torque values were significantly higher in the mandible than in the maxilla. The removal torques of 15-mm and 17-mm miniscrews were significantly higher than those of 13-mm miniscrews. Therefore, the site of implantation and miniscrew length were important factors associated with removal torque. However, there was no significant correlation between the removal torque value and age, gender, healing time, or time in function. DISCUSSION: When miniscrews are used as anchorage for uprighting tipped molars, excessive torque in a counterclockwise direction may loosen them. From the measurements obtained in this investigation, miniscrews can sufficiently sustain an uprighting moment. CONCLUSION: The removal torque values of the majority of miniscrews in this study population when loaded immediately as orthodontic anchorage were greater than 0.89 kg x cm, and this was sufficient for these implants to fulfill their purpose as anchors in 3-dimensional tooth movements.

Adolescent↗
PubMed1993

Muscle activation and the isokinetic torque-velocity relationship of the human triceps surae.

The influence of muscle activation and the time allowed for torque generation on the angle-specific torque-velocity relationship of the triceps surae was studied during plantar flexion using supramaximal electrical stimulation and a release technique on six male subjects [mean (SD) age 25 (4) years]. Torque-velocity data were obtained under different levels of constant muscle activation by varying the stimulus frequency and the time allowed for isometric torque generation prior to release and isokinetic shortening. To eliminate the effects of the frequency response on absolute torque the isokinetic data were normalized to the maximum isometric torque values at 0.44 rad. There were no significant differences in the normalized torques generated at any angular velocity using stimulus frequencies of 20, 50 or 80 Hz. When the muscle was stimulated at 50 Hz the torques obtained after a 400 ms and 1 s pre-release isometric contraction did not differ significantly. However, with no pre-release contraction significantly less torque was generated at all angular velocities beyond 1.05 rad.s-1 when compared with either the 200, 400 ms or 1 s condition. With a 200 ms pre-release contraction significantly less torque was generated at angular velocities beyond 1.05 rad.s-1 when compared with the 400 ms or 1 s conditions. It would seem that the major factor governing the shape of the torque-velocity curve at a constant level of muscle activation is the time allowed for torque generation.

Adult↗
PubMed1995

[Clinical experiences with the torque-segmented arch (TSA)].

The torque segmented archwire presented here led to a good torque transfer in all patients, however this transfer differed on a case by case basis. With regard to the angle 1-NA, the average monthly torque change was 2.34 degrees. The smallest torque transfer was 1 degree; the biggest 5.5 degrees per month. Because the torque segmented arch wires consist of a pseudoelastic material for the anterior teeth and a steel portion for the lateral teeth, the anterior component can be adapted to the patient's individual situation and in addition the lateral components make possible the bending of first, second and third order bends. The dimensions of the superelastic materials are 0.016 x 0.022, 0.017 x 0.025, and 0.018 x 0.025. In all 3 dimensions it is possible to select a torque of 30 degrees or 45 degrees. The use of such arch wires yields the following advantages: 1. Problem-free adaptation to the patient's individual situation. 2. Torque segmented arch wires can be applied in the case of the standard edgewise technique as well as in each case of the straight wire technique. 3. The practitioner is no longer dependent on the torque loss of the archwire and the individual axial position of the incisors. 4. With the help of the torque key it is possible at any time to control the already transferred torque with regard to the occlusal plane. 5. The torque segmented archwire can also be applied in the segmented archwire technique. 6. The torque segmented archwire with right angular or round lateral components is well suited for the retraction of the anterior area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Efficiency of root torquing auxiliaries.

In an experimental typodont study simulating the third stage of Tip-Edge treatment, the effect of five torquing auxiliaries on upper four incisors was assessed using the method of laser reflection. The auxiliaries analysed were: (1) Two-Spurs 0.016", (2) Four-Spurs 0.016", (3) Reciprocal Lateral Torque 0.016", (4) Torque Bar 0.022x0.018", 20 degrees, and (5) Torque Bar 0.022x0.018, 30 degrees. When comparing the wires, the efficiency (amount and speed of root tipping) varied considerably: (1) The Two-Spurs wire was the most efficient auxiliary of the five tested and showed good torque effect on the central incisors. (2) The Four-Spurs wire acting on all four incisors was less efficient than the Two-Spurs wire. (3) The Reciprocal Lateral Torque wire exhibited good palatal root torque on the central incisors and labial root torque on the lateral incisors. (4) The Torque Bars (20 degrees and 30 degrees ) were the least efficient wires of the auxiliaries tested and showed only small torque effects on the central and lateral incisor teeth. In clinical work using the Tip-Edge technique, the Two-Spurs torquing auxiliary should be the wire of choice for an efficient palatal root torque of the upper central incisors.

Journal Article↗