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Biomedical subjects

E Ellis

Publications and source records attributed to E Ellis.

At least 19 recordsLinked to original sources
PubMed1995

Structural properties of mandibular bone following application of a bone plate.

PURPOSE: Similarities in strain patterns between long bones and the mandible suggest that plates may induce stress shielding, resulting in deleterious long-term changes. This study is an investigation of the use of bone plates on the mandible in four adult rhesus monkeys. MATERIAL AND METHODS: A stainless steel plate was attached facially along the inferior border of each mandibular corpus. On the left, a thick (2.5-mm) plate was engaged with four screws. On the right, a thin (0.5-mm) plate was attached with one screw. Monkeys were killed a year after plate placement. At the beginning and end of the experiments, bone strain was recorded inferior to each bone plate during evoked maximal incisal clenching. After death, bone was removed from the mandibles around and under the plates and examined. Gross dimensions and density were measured. An ultrasonic technique was used to measure the material properties, including the elastic and shear moduli. RESULTS: Bone strain inferior to the plates was reduced by 34% to 53% after attachment of the thick plates. Little change in strain was found after attachment of the thin plates. However, no significant differences in structural or mechanical measurements, such as density, cortical thickness, elastic and shear moduli, and Poisson's ratios, were detected between the two sides in each monkey. CONCLUSION: Long-term placement of bone plates, and the resulting stress shielding, were found to result in structural changes in the mandibular corpus.

Animals↗
PubMed1995

The effects of orthodontic treatment on isometric bite forces and mandibular motion in patients before orthognathic surgery.

PURPOSE: Little is known about the effects of orthodontic treatment on oral motor function. The objective of this report is to evaluate changes in mandibular motion and maximum bite force that occur between the initiation of presurgical orthodontics and its completion before surgery. PATIENTS AND METHODS: Fifteen patients (9 women, 6 men) with a variety of dentofacial deformities were examined before and after presurgical orthodontics. Mechanical advantage of the muscles and bite points, mandibular range of motion, maximum isometric bite force, and levels of electromyographic (EMG) activity in the anterior and posterior temporalis and masseter muscles during isometric bites were recorded on all subjects over time. Data obtained before and after completion of presurgical orthodontics were statistically compared. RESULTS: Presurgical orthodontics reduced mandibular mobility somewhat, but the amount was not significant. Statistically significant reductions in bite force were noted after orthodontics for incisor, canine, premolar, and molar bite positions. No significant difference in the EMG/bite force slopes was obtained, nor was there any difference in the moment arms of the bite points or the muscles of mastication from orthodontics. CONCLUSIONS: This study showed significant changes in measures of oral motor function resulting from orthodontic treatment. A larger study is needed to confirm that these results will be similar in all orthodontic patients. There is no indication that these changes are the result of physiologic alterations of the muscles of mastication. The best current explanation is that these changes result from the pain and discomfort of the orthodontic appliances and the induced malocclusion.

Adolescent↗
PubMed1995

Functional characteristics of retrognathic patients before and after mandibular advancement surgery.

PURPOSE: The purpose of this investigation was to compare morphologic parameters and functional performance between controls and a sample of patients with mandibular retrognathia prior to surgical correction, and to examine how oral motor function adapts after treatment. PATIENTS AND METHODS: Twenty-four retrognathic female patients were compared with 26 female controls before and up to 3 years after mandibular advancement surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way analysis of variance was used to compare the controls, the patients before surgery, and the patients after surgery. RESULTS: Surgical lengthening of the mandible averaged 7.3 mm, bringing most skeletal measures into the normal range. There were no significant differences in jaw muscle mechanical advantage between patients and controls before surgery, but surgery significantly reduced mechanical advantage of the anterior temporalis and masseter muscles. Jaw hypomobility was apparent at 6 weeks after surgery, but returned to normal values within 12 to 24 months. Before surgery the patients had maximum isometric bite forces less than half those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite force were equivalent to those of controls or somewhat higher. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. CONCLUSION: The results of this study suggest that correction of mandibular retrognathia by mandibular advancement surgery produces some significant functional benefits.

Adolescent↗
PubMed1995

A longitudinal study of changes in masticatory performance of patients undergoing orthognathic surgery.

PURPOSE: Individuals with developmental deformities of the jaws may be less efficient at chewing food. Previous studies have reported masticatory deficiency in patients with such deformities. This study was designed to detect any changes in masticatory performance that accompany orthognathic surgery. MATERIALS AND METHODS: Masticatory performance was tested in 18 patients with various jaw deformities before application of orthodontic appliances and 2 to 3 years after surgical correction of their malocclusion. A control group was tested at three 6-month intervals. The subjects chewed carrots and masticatory performance was measured using a standard sieve technique. The Rosin-Rammler equation was used to calculate the median particle size and broadness index of each set of carrots. The number of chewing cycles required for each subject to swallow one piece of carrot was also recorded. RESULTS: A statistically significant difference in median particle size between patients and controls was found both preoperatively and postoperatively (P < .05), but no difference in median particle size or broadness index was seen between trials for controls or patients (P > .05). CONCLUSION: It was concluded that before surgery patients have a lower level of performance than controls and surgical correction of the malocclusion does not significantly enhance performance.

Adolescent↗
PubMed1995

Functional and morphologic alterations secondary to superior repositioning of the maxilla.

PURPOSE: The purpose of this investigation was to 1) compare morphological characteristics and functional performance of a sample of patients with vertical maxillary excess (VME) with controls, and to 2) examine how the patients' oral motor function adapts to surgery. MATERIALS AND METHODS: Fifteen female VME patients were compared with 26 female controls before and up to 3 years after maxillary intrusion surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyogram (EMG) activity in some of the muscles of mastication were made on all subjects over time. One-way analysis of variance (ANOVA) was used to compare the controls with the patients before and after surgery. Univariate repeated measures ANOVA was used to study longitudinal changes in the patients. RESULTS: Preoperatively, the patients possessed morphological measurements characteristic of vertical maxillary excess. Superior repositioning of the maxilla averaged 3.3 mm. Concurrently, most skeletal measures were brought closer to normal values. Masseter muscle mechanical advantage was significantly lower in the patients than in controls both before and after surgery (P < or = .05). There was no significant difference between patients and controls for other biomechanical measurements. Mandibular hypomobility was apparent at 6 weeks after surgery, but returned to control values within 6 to 12 months. Before surgery, the patients had maximum isometric bite forces significantly less than those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite forces were equivalent to those of controls or somewhat lower. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. CONCLUSIONS: The results of this study suggest that correction of vertical maxillary excess with maxillary intrusion surgery improves some characteristic functional deficits.

Adolescent↗
PubMed1995

Breathing patterns during spontaneous speech.

Lung volumes, speech intensity, the linguistic location of inspirations, and the variability of each, were studied during spontaneous speech in 6 healthy young women over 7 to 10 sessions each, using respiratory inductance plethysmography. Although average lung volume levels were within the vital capacity range previously reported for speech (Hixon, Goldman, & Mead, 1973), significant inter- and intrasubject variability was observed. This variability was considerable for some subjects (average initiation lung volume varying between 42 and 63% VC over the sessions) and relatively small for others (between 47 and 53% VC). Some of the lung volume variation was associated with changes in mood state, examined by self-report questionnaire at each measurement occasion. Linguistic factors were important influences in the lung volume variation. The majority of breaths in the conversations and monologues preceded structural (clause) boundaries. The volume of air inspired preutterance was found to be linked to the length of the ensuing breath group in each of our 6 subjects, as longer breath groups, spanning up to seven clauses in the spontaneous speech, were anticipated by inspiring to a higher lung volume. The subjects used a comfortable speaking intensity range, which varied for different individuals and sessions over 4 to 18 dB. Increases in speech intensity within individual ranges were not associated with increased lung volumes. The data provide novel insight into associations between physiological and linguistic factors in the control of speech breathing, and are suggestive of the existence of neural planning of the respiratory system, in anticipation of the demands of the utterance.

Adult↗
PubMed1994

Treatment of mandibular angle fractures using two noncompression miniplates.

PURPOSE: To evaluate treatment with two 2.0-mm noncompression miniplates for patients with angle fractures. PATIENTS AND METHODS: Sixty-seven consecutive patients with 69 fractures of the mandibular angle were treated by open reduction and internal fixation using two noncompression miniplates and 2.0-mm self-threading screws placed through a transoral incision with transbuccal trochar instrumentation. No patient was placed into postsurgical maxillomandibular fixation or elastics. RESULTS: Overall, 19 fractures (28%) experienced complications requiring secondary surgical intervention. Most of the complications were postoperative infections requiring surgical drainage (n = 17) and subsequent hardware removal (n = 16). Of the 17 infected fractures, 11 were healed at the time of hardware removal and required no further treatment. Five were still mobile and required a period of maxillomandibular fixation for healing. One of the fractures did not heal and required bone grafting. CONCLUSION: The use of two noncompression miniplates was found to be relatively easy, but resulted in an unacceptable rate of infection in our patient population when used for treatment of fractures of the mandibular angle.

Adolescent↗
PubMed1994

Masticatory performance, muscle activity, and occlusal force in preorthognathic surgery patients.

Previous studies have indicated that patients scheduled for orthognathic surgery tend to have lower maximum bite forces and exert lower forces during mastication. The effect of these deficits on masticatory performance have not been previously assessed. Masticatory performance was analyzed in four groups: male and female orthognathic surgery patients prior to presurgical orthodontics (n = 12 and 23), and male and female controls (n = 27 and 31). Mastication performance was analyzed by having the subjects chew 5-g pieces of carrot for 20 cycles and measuring the resulting median particle size with a standard sieve method. Masticatory performance showed the same trends as maximum bite force and masticatory forces: male controls had the best and patients the poorest masticatory performance. There was a weak correlation between masticatory performance and maximum bite force at the molar positions. Masticatory performance also weakly correlated to electromyographic signals during mastication of a constant bolus (gummy bears) for all muscles except the left posterior temporalis. Correlations were generally not present or were very weak between masticatory performance, estimated masticatory forces, and muscle efficiency, suggesting that muscle efficiency and forces generated during mastication are not the primary factors that determine masticatory performance. Other factors contributing to a person's ability to chew food might include occlusal relationships and mechanical advantage.

Adolescent↗
PubMed1994

Bite forces in patients treated for mandibular angle fractures: implications for fixation recommendations.

Voluntary bite forces were recorded at varying periods in 35 males treated with rigid internal fixation for fractures of the mandibular angle. Bite forces were also obtained in 29 male controls for comparison. It was found that molar bite forces in patients were significantly less than in controls for several weeks after surgery. Further, molar bite forces on the side of the fracture were significantly less than on the nonfractured side. The results of this study indicate that recommendations for the amount of fixation required for a given fracture may be reduced.

Adolescent↗
PubMed1994

Connective tissue forces from mandibular advancement.

PURPOSE: To quantify the connective tissue forces generated during surgical lengthening of the mandible. PATIENTS AND METHODS: Sixty-three patients who had mandibular advancements by sagittal ramus osteotomy were used in this study. Prior to sectioning the rami, the overjet was recorded. After sectioning the rami, a spring-gauge was attached to the mandibular orthodontic wire and pulled anteriorly to determine how much force was necessary to bring the mandibular incisors into a Class I relationship with the maxillary incisors. Aggressive stripping of the perimandibular periosteum and connective tissues on the distal segment was then performed. The amount of force was again recorded. RESULTS: The mean preoperative overjet in the 63 patients was 6 mm (range, 3 to 11 mm). The mean amount of force required to advance the mandible prior to stripping the tissues was 1,498 g compared with a mean of 787 g after stripping (P < .001). There were statistically significant correlations between the preoperative overjet and the prestripping and poststripping force levels (P < .001). There was also a significant relationship between prestripping and poststripping values (P < .001). CONCLUSION: The results of this study indicate that orthopedic forces are generated by the perimandibular connective tissues following advancement by the mandible. The effect of these forces on the temporomandibular joint should be evaluated in future studies.

Bone Resorption↗
PubMed1994

Variability and consistency in speech breathing during reading: lung volumes, speech intensity, and linguistic factors.

Lung volumes during reading and associated factors such as speech intensity and linguistic influences were studied in six healthy young women over 7 to 10 sessions, using respiratory inductive plethysmography. Intrasubject variability of lung volumes over the sessions was almost as great as the intersubject variability. Some of the intrasubject variability was associated with natural variations of speech intensity within a "comfortable loudness" range. The lung volume variability during reading is contrasted with high degrees of both inter- and intrasubject consistency in the location of inspirations, which occurred almost exclusively at grammatically appropriate places in the texts (paragraph, sentence, clause, and phrase boundaries). Within each reading passage, lung volumes were significantly increased for (a) louder utterances, (b) inspirations at sentence and paragraph boundaries compared to inspirations at other locations within sentences, (c) longer utterances compared to shorter utterances, and (d) initial breaths compared to final breaths. The implications of these findings for the neural control of breathing during speech are considered.

Adult↗
PubMed1992

Validation of respiratory inductance plethysmography ("Respitrace") for the measurement of tidal breathing parameters in newborns.

INTRODUCTION: The ratio of the time to reach peak (maximum) tidal expiratory flow (Tme) to total expiratory time (Te) is smaller in infants who later develop lower respiratory tract disease. In previous studies infants have been sedated and flow measured using a pneumotachograph with face-mask. These methodological factors are known to affect tidal breathing, and the frequent need for sedation limits the use of the technique to relatively small studies. The aim of this study was to validate uncalibrated respiratory inductance plethysmography (Respitrace) to measure Tme/Te in unsedated newborns. METHODS: Nineteen normal term infants were studied during quiet sleep. Agreement between Tme/Te measured directly using a pneumotachograph and with Respitrace was assessed in 15 infants. Repeatability of the Respitrace technique was assessed in 10 infants. RESULTS: The mean Tme/Te for the 19 infants using Respitrace was 0.46 (S.D. 0.14). The mean difference between Tme/Te obtained using Respitrace and that measured with a pneumotachograph was 0.014; 95% of Respitrace readings were between -0.042 and 0.070 of the pneumotachograph values. The mean difference between repeat Respitrace values was 0.02 with 95% of the second measurements within 0.066 of the first. CONCLUSIONS: These results indicate that Respitrace can be used to determine Tme/Te accurately.

Evaluation Studies as Topic↗
PubMed1992

Gut protection by cyclophosphamide "priming" in patients receiving high-dose melphalan--effect of drug scheduling.

A "priming" injection of cyclophosphamide (400 mg/m2 given i.v. on day -7) has been shown to reduce intestinal permeability and thus gut toxicity in patients receiving high-dose melphalan. To determine the optimal timing for this injection, patients receiving 200 mg/m2 melphalan with an autologous bone marrow transplant were randomly assigned to receive cyclophosphamide at 5, 7 or 9 days before the melphalan. The median percentage of [51Cr]-ethylenediaminetetraacetic acid excretion was similar (9.1% vs 7.1% vs 7.7%, respectively), with equivalent duration of WHO grade 2-4 mucositis and diarrhoea being recorded for each group. Thus, the timing of the cyclophosphamide prime is not critical, and the priming injection may be given between 5 and 9 days prior to high-dose melphalan.

Bone Marrow Transplantation↗
PubMed1992

Reproducibility of mandibular motion and muscle activity levels using a commercial computer recording system.

A commercial computer recording system (BioPak) was tested for its accuracy and reproducibility in recording mandibular motion and muscle activity levels (EMG). Accuracy of measurements of mandibular motion was tested using sliding calipers. Accuracy of muscle activity levels was checked with a sine-wave calibration signal of known amplitude and frequency. Reproducibility of motion and of EMG was made using five control subjects each tested on 3 separate days. Computer measurements of motion were found to require correction for nonlinearity at openings beyond 45 mm. Most maximum voluntary excursions were found to be more reproducible than motions during mastication. However, lateral deviation during opening was strongly affected by magnet orientation and varied greatly between trials. Electromyographic recordings were distorted by improper treatment of high-frequency components of the signal and also varied greatly between trials. This study suggests that the BioPak system may indicate changes in some measures of mandibular motion and EMG levels in patients for whom no changes have occurred.

Adult↗
PubMed1992

Reproducibility of data from a hand-held digital pulp tester used on teeth and oral soft tissue.

Controlled studies of the reproducibility of data from electronic pulp testing instruments are limited and contain few statistical analyses. The reproducibility of these readings is important if the instrument is to be used for determining differences in sensitivity. Twenty human subjects (16 male) were used in this study. One incisor, one premolar, one molar tooth with small or no restorations, and two gingival soft tissue positions from each upper and lower arch of each subject were stimulated with the Analytic Technology vitality scanner. This procedure was repeated twice with a 5-minute rest between each trial, for a total of three trials. Each subject was then seen again after a period of at least 3 days, at which time the trials were repeated. The collected data were grouped by trial, tooth position, and day. Paired t test analysis of both the absolute difference between any two trials on the same day and the average of the absolute differences between corresponding trials on days 1 and 2 showed no statistically significant differences (p greater than 0.05). Accommodation to the stimulus was evaluated by examining differences in the mean values between the three same-day trials. The Analytic Technology vitality scanner was found to be reproducible both for consecutive same-day trials and for corresponding trials on different days. No same-day trends in meter readings were noted.

Adult↗