Isometric endurance of the human masseter muscle during consecutive bouts of tooth clenching

Isometric endurance of the human masseter muscle during consecutive bouts of tooth clenching

Am. J. Orthod. 448 Reviewsand abstracts with the spatial orthogonal coordinates. This is done with a newly developed opto-electronic noncontact prof...

231KB Sizes 1 Downloads 32 Views

Am. J. Orthod.

448 Reviewsand abstracts

with the spatial orthogonal coordinates. This is done with a newly developed opto-electronic noncontact profilometer. Graphical description of the measurements from the occlusal view is completed through uncoiling of the surface area of the space enclosed by a parallel baseline at the height of the dorsal lower surface of the vomer to the alveolar crest line and to the occlusal plane. This graphical description gives information on the growth and development of cleft palate infants when models are superimposed. Alex Jacobson

Intraoral Self-Threading Screw Fixation for Sagittal Osteotomies: Early Experiences T. A. Turvey and D. J. Hall Int. J. Adult

Orthodon.

Orthognath.

Surg.

1986;1:243-50

Since Trauner and Obwegeser stimulated interest in the sagittal osteotomy of the mandibular ramus, rigid fixation has become commonplace for the correction of a variety of mandibular deformities. According to the authors, essential for the success of this operation are (1) placement of the proximal segment to properly position the condyle in the glenoid fossa and (2) securing the proximal segment to the distal segment without altering the ramus length. The article represents the authors’ experience with 60 cases of transoral placement of self-threading screws to stabilize the proximal and distal segments following sagittal osteotomy. The results of the procedure so far have been favorable. According to the authors, temporomandibular joint fixation, occlusal changes, and neurosensory recovery are areas of fruitful investigation for the future. Alex Jacobson

Maxillary Osteotomies Utilizing the Rigid Adjustable (RAP) System: A Review of 31 Clinical Cases FL A. Bays Int. J. Adult

Orthodon.

Orthognath.

. Surg.

1986;1:275-97

Positioning and stabilization of the maxilla following osteotomy is at times challenging to the surgeon because certain movements of the maxilla, such as advancement, correction of asymmetries, superior positioning when bone contact is poor, and practically all cleft osteotomies, are more problematic than others. The primary purpose of fixation is to prevent postoperative movement of the maxilla while healing takes

Dentofac. Orthop. November 1987

place. Frequently, following repositioning of the maxilla, bony contacts are sparse owing to thin telescoping osteotomy sites on thin unsupporting bone. Interposed bone grafts at the points of minimal contact are traditionally managed with a rigid fixation system using bone plates. The disadvantages of bone plating are that it can be a problem if insufficient bone thickness is not available and it allows for no postsurgical adjustment when the patient is under general anesthetic. To overcome these problems, the author uses a rigid adjustable pin (RAP) system that, when properly placed, provides extremely stable and rigid fixation of the maxilla during the healing phase. The advantage of the procedure is that it allows for correct and precise positioning of the maxilla under anesthesia before final fixation. Data from 31 surgical cases with a minimum of 16 months are analyzed for complications and longterm stability, the latter of which was found to be excellent. The article is well documented with excellent illustrations describing aspects of the system. Alex Jacobson

Isometric Endurance of the Human Masseter Muscle During Consecutive Bouts of Tooth Clenching L. V. Christensen, S. E. Mohamed, and J. D. Rugh J. Oral

Rehabil.

1985;12:509-14

Three adult male subjects in good health and without demonstrable dysfunctions of the mandibular locomotor system performed teeth clenching at maximum voluntary contraction of the mandibular elevator muscles. At lo-second intervals, ten successive bouts of clenching were conducted until total exhaustion of the contracting muscles occurred. The isometric endurance time decreased from 59 seconds to 12 seconds. The largest decline occurred between the first and second trials. Electromyographic recordings of the masseter muscles were taken during 10 seconds of maximum voluntary contraction and during the first and last of the series of endurance tests. The silent period was increased 35% from the first to last endurance test from a mean of 19 ms to a mean of 26 ms. The authors suggest that muscle and/or central nervous system fatigue may be factors in increasing the mean silent period observed during these trials. The three subjects experienced severe pains in the masseter and anterior temporalis muscles, the zygomatic arches, along the inferior border of the mandible, and in the tongue, the throat, the neck, and the shoulder girdle. Perspiration, pronounced tremors of the head

Reviews

and neck, nausea, and vomiting were also produced. The authors suggest that muscle pain and the other signs and symptoms may result from one or more unknown chemical substances related to ischemia in the masseter muscle and other muscles associated with maximal voluntary contraction of the mandibular elevator muscles. Comment. Although the EMG silent period was increased by muscle fatigue, neither the tissue site nor the nature of the increase were identified or isolated by this study. Tom Zwemer

The Epidemiology of Quality Avedis Donalbedian J. Health Care 1985:22:2,62-9

Organization,

Provision,

and Financing

The quality of health care has an epidemiology in the sense that it is distributed within both the provider and consumer populations. This article attempts to determine and describe the distribution of quality in both populations and to identify the factors responsible for, or contributory to, that distribution. Although the author uses the medical profession and its patients rather than the dental or orthodontic professions and their patients, there are important lessons for our profession in this article. Since quality is not a scalar attribute, it is not subject to measurement and assessment in a classic scientific sense. Quality of care is usually implied from the observed association of such corollaries as reports of morbidity, mortality, longevity, use of service, and/or complaints and grievances. (The quality of dental care has scalar attributes of form, fit, and function.) However, this article includes 121 references to articles and reports on quality assessment of medical care over the past decade. The author concludes that the quality of technical care is positively .related to the: quantity and quality of training, the degree of specialization, and the amount of clinical experience, aging e.xcepted. The quality of ambulatory care is positively related to patient scheduling, control of caseload, quality of equipment and premises, and association with equally or better trained and qualified colleagues. The quality of inpatient care is positively related to the control of staff privileges and responsibilities, the size of the institution, and its teaching and research functions. No clear national pattern emerged as to the quality of care relative to proprietary or public hospitals, nor was a clear relationship of quality demon-

and

abstracts

449

strated between urban or rural hospitals after factoring out such variables as staff control, size, and affiliations with teaching institutions. The literature indicates an astonishing degree of variability among geographic locations, practitioners, and institutions. However, no consistent relationship was found between quality of care received by the patient based upon age, sex, rurality, occupation, income, or ethnicity. There was sufficient indication that socioeconomic disadvantage and poor technical care are positively related to compel the author to call for prompt and careful study of this issue with the implication that rectification was not only necessary but urgent. Comment: Among the lessons for us are the relationship of quality to the extent and quality of training and experience, the relationship to scheduling, caseload, and state-of-the-art facilities and equipment, and the association with peers of equal or superior clinical background. We conclude that the AA0 logo should and does mean something in terms of the epidemiology of quality among orthodontists and their patients/ clients. Tom Zwemer

Masseter Muscle Silent Period in Patients With Internal Derangement of the Temporomandibular Joint Before and After Splint Therapy Benjamin Hanson, Richard Sherman, and Anthony Ficara J. Prosthet.

Dent.

198.5:54:846-50

Nineteen adult patients with internal derangement of the TMJ and minimal amount of muscle hyperactivity (MPD) were matched with 15 patients in good health without history of TMJ dysfunction or pain. Seven of the TMJ patients declined treatment and formed a selfselect, no-treatment control group. All subjects participated in at least one EMG recording session. The seven nontreated TMJ subjects were recorded at the beginning and end of a 3-month experimental period. The remaining 12 subjects were recorded before anterior repositioning splint placement, immediately following splint placement, at l-month intervals during splint use and at the end of the 3-month period both with and without the splint in place. (At the initial session, a videothermograph was taken bilaterally on each subject. No differences in blood flow to the preaurical region could be visualized with the videothermograph.) Each subject was measured for maximal opening and observed for deviations of the mandible upon opening.