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Electromyographic turns analysis of sustained contraction in human masseter muscles at various isometric force levels
J Oral Maxillofac 52:526-530.
Surg
1994
Abstracts The Effect of Instruction on Dentists’ Motivation to Manage Fearful Patients. Tay K, Winn W, Milgrom P, et al. J Dent Educ 571444, I993
an increase in contraction strength. with the overall ratio being less at the end of a sustained contraction. This ratio was not significantly decreased at the .05 level but was decreased at the .I0 level. These results indicate and support the conclusion that neuromuscular fatigue is not evident with sustained contraction of the masseter muscle.-M.J. RISER
Patients’ fears of dentistry are helped by pharmacologic and behavioral methods. This study compares the efforts to treat fearful patients by recent graduates who have received predoctoral and/or continuing behavioral education regarding the management of fearful patients. Mail surveys were sent to 1988 and 1989 graduates of three North American dental schools. Of those surveyed, 80.4% responded. They were placed into three groups. Eighty-five graduates reported receiving instruction in predoctoral behavioral science education, 43 reported receiving continuing dental education on the subject, and 36 received pharmacologic-oriented instruction alone. The results of the survey indicate that the dentists who received behavioral instruction reported 1) a significantly higher proportion of fearful adult patients, and 2) greater effort addressing fear issues during the patients’ initial contact with the practice. No difference was found between the groups for efforts to 1) provide training for support staff, 2) address the fear issue in the health questionaire, 3) address the fear issue during the initial interview, 4) practice active listening. 5) increase the patients’ perceived control in the dental situation, and 6) teach the patient coping strategies. Those dentists who received instruction in behavioral approaches were less likely to believe in its cost effectiveness. The authors conclude that behavioral science instruction was successful in motivating graduates to identify barriers that hinder fearful patients from receiving care during the patients’ initial contact with the practice. They also suggest that instruction in the behavioral approach to fear reduction strategies is successful and should be further developed, indicating a need for increasing instructional effectiveness.-P.S. LAM
Reprint requests to Dr Junge: School of Dentistry and Dental Research Institute. University of California, Los Angeles. CA 90024. Thrombolysis and Myocardial Salvage: Results of Clinical Trials and the Animal Paradigm-Paradoxic or Predictable? Gersh BJ, Anderson JL. Circulation 296, 1993 The era of acute reperfusion as a modality in the treatment of acute myocardial infarction has without a doubt had a large impact on the overall outcome of these patients. It has been demonstrated that the restoration of coronary blood flow does indeed reduce mortality. and that the earlier therapy is initiated, the greater the benefits. This article is a review of numerous clinical trials that address the effects of thrombolytic therapy on myocardial salvage and the significance of “early” versus “late” initiation of treatment. The use of isotope technetium sestambi has provided an important mode in which the extent of myocardial salvage can be appreciated in humans following acute reperfusion. The greatest benefits are evident when treatment is rendered within the first I to 2 hours, with only intermediate benefits gained if therapy is delayed for 2 to 6 hours. Conclusions showed a direct relationship between mortality rates and treatment delays, and greater evidence of frequent episodes of recurrent ischemia in individuals treated within the first hour implied greater initial myocardial salvage due to a greater extent ofjeoparized myocardium vulnerable to recurrent ischemia. Therefore. decreasing the time from symptoms to therapy (“symptomsto-needle time”) may have significant beneficial effects on ejection fraction, infarct size, and mortality. Also reviewed was the so-called “late” sustained reperfusion or time-independent myocardial salvage and its stabilizing effect on myocardial electrical impulses and ventricular remodeling, where late reperfusion may be of benefit days or even weeks after infarction. Based on the review of these studies, the focus of acute reperfusion in the years to come will be on delivering therapy more quickly and efficiently, relegating the development of more effective and rapid thrombolytic drugs to a complimentary role.-B.P. MCANDREW
Reprint requests to Dr Milgrom: Department of Dental Public Health Sciences, SM-35. Seattle. WA 98 195. Electromyographic Turns Analysis of Sustained Contraction in Human Masseter Muscles at Various Isometric Force Levels. Junge D. Clark CT. Arch Oral Biol 38:583. 1993 It has been noted that the maximum voluntary contraction of peripheral limb muscles decays progressively during a sustained contraction. When neuromuscular fatigue is present, there is an increase in the averaged electromyogram (EMG) to maintain the isometric force at a constant level. This neuromuscular fatigue that is found in the limb muscles is apparently not found in the masseter muscle. With this masticator muscle, the averaged EMG and force are decreased together during a sustained contraction. This present study assessed the changes in the EMG signals of the masseter muscle during sustained isometric contractions using the turns analysis. Results showed no significant change in averaged rectified EMG values before and after fatiguing contractions at all levels: however, there was a decrease in the number of turns per .5 seconds at all levels at the end of sustained contractions. The EMG/force ratio showed no significant difference at the .05 or .10 levels at the beginning or end of contraction. Furthermore. the turns/force ratio decreased with
Reprint requests to Dr Gersh: Cardiovascular Division, Georgetown University Medical Center, 3800 Reservoir Rd NW. Washington. DC 20007. Induction of Reparative Dentine Formation in Monkeys by Recombinant Human Osteogenic Protein-l. Rutherford RB. Wahle J, Tucker M. Arch Oral Biol 38:571. 1993 It is known that osteogenic protein- 1 (OP- 1) has the ability to induce cartilage and bone formation when implanted in vivo. The amount of bone induced by OP- 1 in vivo is related to the amount of protein implanted. Dentine has bone morphogenic protein activity. It was the objective of this study
526
Surg
1994
Abstracts The Effect of Instruction on Dentists’ Motivation to Manage Fearful Patients. Tay K, Winn W, Milgrom P, et al. J Dent Educ 571444, I993
an increase in contraction strength. with the overall ratio being less at the end of a sustained contraction. This ratio was not significantly decreased at the .05 level but was decreased at the .I0 level. These results indicate and support the conclusion that neuromuscular fatigue is not evident with sustained contraction of the masseter muscle.-M.J. RISER
Patients’ fears of dentistry are helped by pharmacologic and behavioral methods. This study compares the efforts to treat fearful patients by recent graduates who have received predoctoral and/or continuing behavioral education regarding the management of fearful patients. Mail surveys were sent to 1988 and 1989 graduates of three North American dental schools. Of those surveyed, 80.4% responded. They were placed into three groups. Eighty-five graduates reported receiving instruction in predoctoral behavioral science education, 43 reported receiving continuing dental education on the subject, and 36 received pharmacologic-oriented instruction alone. The results of the survey indicate that the dentists who received behavioral instruction reported 1) a significantly higher proportion of fearful adult patients, and 2) greater effort addressing fear issues during the patients’ initial contact with the practice. No difference was found between the groups for efforts to 1) provide training for support staff, 2) address the fear issue in the health questionaire, 3) address the fear issue during the initial interview, 4) practice active listening. 5) increase the patients’ perceived control in the dental situation, and 6) teach the patient coping strategies. Those dentists who received instruction in behavioral approaches were less likely to believe in its cost effectiveness. The authors conclude that behavioral science instruction was successful in motivating graduates to identify barriers that hinder fearful patients from receiving care during the patients’ initial contact with the practice. They also suggest that instruction in the behavioral approach to fear reduction strategies is successful and should be further developed, indicating a need for increasing instructional effectiveness.-P.S. LAM
Reprint requests to Dr Junge: School of Dentistry and Dental Research Institute. University of California, Los Angeles. CA 90024. Thrombolysis and Myocardial Salvage: Results of Clinical Trials and the Animal Paradigm-Paradoxic or Predictable? Gersh BJ, Anderson JL. Circulation 296, 1993 The era of acute reperfusion as a modality in the treatment of acute myocardial infarction has without a doubt had a large impact on the overall outcome of these patients. It has been demonstrated that the restoration of coronary blood flow does indeed reduce mortality. and that the earlier therapy is initiated, the greater the benefits. This article is a review of numerous clinical trials that address the effects of thrombolytic therapy on myocardial salvage and the significance of “early” versus “late” initiation of treatment. The use of isotope technetium sestambi has provided an important mode in which the extent of myocardial salvage can be appreciated in humans following acute reperfusion. The greatest benefits are evident when treatment is rendered within the first I to 2 hours, with only intermediate benefits gained if therapy is delayed for 2 to 6 hours. Conclusions showed a direct relationship between mortality rates and treatment delays, and greater evidence of frequent episodes of recurrent ischemia in individuals treated within the first hour implied greater initial myocardial salvage due to a greater extent ofjeoparized myocardium vulnerable to recurrent ischemia. Therefore. decreasing the time from symptoms to therapy (“symptomsto-needle time”) may have significant beneficial effects on ejection fraction, infarct size, and mortality. Also reviewed was the so-called “late” sustained reperfusion or time-independent myocardial salvage and its stabilizing effect on myocardial electrical impulses and ventricular remodeling, where late reperfusion may be of benefit days or even weeks after infarction. Based on the review of these studies, the focus of acute reperfusion in the years to come will be on delivering therapy more quickly and efficiently, relegating the development of more effective and rapid thrombolytic drugs to a complimentary role.-B.P. MCANDREW
Reprint requests to Dr Milgrom: Department of Dental Public Health Sciences, SM-35. Seattle. WA 98 195. Electromyographic Turns Analysis of Sustained Contraction in Human Masseter Muscles at Various Isometric Force Levels. Junge D. Clark CT. Arch Oral Biol 38:583. 1993 It has been noted that the maximum voluntary contraction of peripheral limb muscles decays progressively during a sustained contraction. When neuromuscular fatigue is present, there is an increase in the averaged electromyogram (EMG) to maintain the isometric force at a constant level. This neuromuscular fatigue that is found in the limb muscles is apparently not found in the masseter muscle. With this masticator muscle, the averaged EMG and force are decreased together during a sustained contraction. This present study assessed the changes in the EMG signals of the masseter muscle during sustained isometric contractions using the turns analysis. Results showed no significant change in averaged rectified EMG values before and after fatiguing contractions at all levels: however, there was a decrease in the number of turns per .5 seconds at all levels at the end of sustained contractions. The EMG/force ratio showed no significant difference at the .05 or .10 levels at the beginning or end of contraction. Furthermore. the turns/force ratio decreased with
Reprint requests to Dr Gersh: Cardiovascular Division, Georgetown University Medical Center, 3800 Reservoir Rd NW. Washington. DC 20007. Induction of Reparative Dentine Formation in Monkeys by Recombinant Human Osteogenic Protein-l. Rutherford RB. Wahle J, Tucker M. Arch Oral Biol 38:571. 1993 It is known that osteogenic protein- 1 (OP- 1) has the ability to induce cartilage and bone formation when implanted in vivo. The amount of bone induced by OP- 1 in vivo is related to the amount of protein implanted. Dentine has bone morphogenic protein activity. It was the objective of this study
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