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Sound-and surface electro-myography of human jaw elevator muscles
390
Reviews and abstracts
of nasal airway obstruction and obligate mouth breathing on facial development. The morphologic changes in the nasal and oral passages of growing children present the possibility that respiratory mode changes over time. Existing methods for quantifying RM can be time consuming, expensive, and intimidating to children. In this study we report on the development of an improved method for quantifying RM and its use to assess variation in RM within a few hours and over a period of weeks. Twenty-nine children, 19 boys and I1 girls, 7 to 10 years, were assessed three times per session for RM, nasal resistance, and nasal x-sectional area on 3 days separated by a minimum of 1 week. Respiratory mode was measured with inductive plethysmography, nasal resistance with posterior rhinometry, and area by the method of Warren. A two-factor ANOVA revealed that the variation in RM from study to study within any one d~y was not significant (P > 0.64); however, RM measures among different days were significantly different from each other (p < 0.01). Further analysis of the data revealed that the variation in the respiratory behavior of a subject could be categorized into one of four basic groups: (1) consistent RM within and among days (7/29), (2) consistent within any day, but significantly different from day to day (4/29), (3) large daily variation with moderate to high total variation (9/29), and (4) consistent RM on 2 days with large deviation on 1 of the 3 days (10/29). The results of this study suggest that significant variation exists in RM measured on different days in preadolescent children. In this population the variation in RM can be categorized into one of four basic groups, and a single airway evaluation would not be a good predictor of a person's overall airflow partitioning and that clinical decisions on the basis of such an evaluation would be unwise.
The periodontal status of teeth adjacent to non-grafted unilateral alveolar clefts Z. Teja Department of Orthodontics, University of Washhzgton, Seattle, Wash., 1991.
Few studies have examined the periodontal status of teeth adjacent to an alveolar cleft. The purpose of this study was to compare the periodontal condition of teeth adjacent to the cleft with contralateral teeth in adult subjects with a nongrafted unilateral alveolar cleft. Periodontal parameters were evaluated in 18 subjects who had at least one tooth adjacent to the cleft. For each tooth being investigated, plaque index, gingival index, and probing depth were recorded at six sites. -A standardized force probe was used for measuring probing depth. Width of attached gingiva and quantity of
Am. J. Orthod. Dentofac. Orthop. April 1992
recession were recorded at the midbuceal aspect, and each tooth was assigned a mobility score. Bone level was assessed with magnified periapical radiographs and a computerized digitizing system. Bone loss was more pronounced on the distal surface of the central incisor adjacent to the cleft than on the distal surface of the control incisor (p < 0.01). Tooth mobility was increased for teeth adjacent to the cleft compared with contralateral teeth (p < 0.001). The findings of this study support those of Bragger et al. (1985-1990) and Ramstad (1989), that in persons with an unrepaired alveolar cleft, teeth adjacent to the defect are not more periodontally compromised than contralateral teeth. The anatomic defect, as well as the presence of restorations, appear to contribute to the reduced bone level on the central incisor adjacent to the cleft.
Sound- and surface electro-myography of human jaw elevator muscles D. C. Pham University of Tennessee, Memphis, Tenn., 1991.
The three objectives of this study were (1) to study the relationship between isometric incisor bite force and the surface electromyogram (EMG) and the sound myogram (SMG) from four jaw elevator muscles, (2) to determine the amplitude and frequency content of SMG detected during isometric incisor biting, and (3) to evaluate the relationship between bite force and different measures of craniofacial morphology obtained from the lateral cephalogram. SMGs and surface EMGs were obtained from anterior temporalis (bilateral) and masseter (bilateral) muscles at six levels of incisor bite force (0% to 30% maximum voluntary contraction, or MVC) for 13 subjects. Each force level was maintained for 4 s; digitzation occurred at 256/s. For the different subjects, and for a constant incisor gape, the magnitude of the 30% MVC incisor bite force was correlated with: (1) the EMG level at 30% MVC; (2) the Frankfort mandibular angle; (3) the palatal plane angle; (4) the gonial angle; (5) the lateral area of masseter muscle; (6) the coronoid process area; and (7) the masseter angle. There was a nearly linear, positive relation between rms EMG and bite force. SMG amplitude (rms) increased to a maxinmm at a low force level and remained constant or decreased for higher forces. For SMG spectra, frequency components ranged from 5 to 30 Hz with one or two major bands present in both mandibular muscles. Two bands, if present, had peak frequencies between 10 to 14 Hz and 15 to 20 Hz. SMG spectra indicated a shift toward higher frequencies with increased tension. The SMG may not be useful as an indicator of force (or fatigue) of jaw muscles.
Reviews and abstracts
of nasal airway obstruction and obligate mouth breathing on facial development. The morphologic changes in the nasal and oral passages of growing children present the possibility that respiratory mode changes over time. Existing methods for quantifying RM can be time consuming, expensive, and intimidating to children. In this study we report on the development of an improved method for quantifying RM and its use to assess variation in RM within a few hours and over a period of weeks. Twenty-nine children, 19 boys and I1 girls, 7 to 10 years, were assessed three times per session for RM, nasal resistance, and nasal x-sectional area on 3 days separated by a minimum of 1 week. Respiratory mode was measured with inductive plethysmography, nasal resistance with posterior rhinometry, and area by the method of Warren. A two-factor ANOVA revealed that the variation in RM from study to study within any one d~y was not significant (P > 0.64); however, RM measures among different days were significantly different from each other (p < 0.01). Further analysis of the data revealed that the variation in the respiratory behavior of a subject could be categorized into one of four basic groups: (1) consistent RM within and among days (7/29), (2) consistent within any day, but significantly different from day to day (4/29), (3) large daily variation with moderate to high total variation (9/29), and (4) consistent RM on 2 days with large deviation on 1 of the 3 days (10/29). The results of this study suggest that significant variation exists in RM measured on different days in preadolescent children. In this population the variation in RM can be categorized into one of four basic groups, and a single airway evaluation would not be a good predictor of a person's overall airflow partitioning and that clinical decisions on the basis of such an evaluation would be unwise.
The periodontal status of teeth adjacent to non-grafted unilateral alveolar clefts Z. Teja Department of Orthodontics, University of Washhzgton, Seattle, Wash., 1991.
Few studies have examined the periodontal status of teeth adjacent to an alveolar cleft. The purpose of this study was to compare the periodontal condition of teeth adjacent to the cleft with contralateral teeth in adult subjects with a nongrafted unilateral alveolar cleft. Periodontal parameters were evaluated in 18 subjects who had at least one tooth adjacent to the cleft. For each tooth being investigated, plaque index, gingival index, and probing depth were recorded at six sites. -A standardized force probe was used for measuring probing depth. Width of attached gingiva and quantity of
Am. J. Orthod. Dentofac. Orthop. April 1992
recession were recorded at the midbuceal aspect, and each tooth was assigned a mobility score. Bone level was assessed with magnified periapical radiographs and a computerized digitizing system. Bone loss was more pronounced on the distal surface of the central incisor adjacent to the cleft than on the distal surface of the control incisor (p < 0.01). Tooth mobility was increased for teeth adjacent to the cleft compared with contralateral teeth (p < 0.001). The findings of this study support those of Bragger et al. (1985-1990) and Ramstad (1989), that in persons with an unrepaired alveolar cleft, teeth adjacent to the defect are not more periodontally compromised than contralateral teeth. The anatomic defect, as well as the presence of restorations, appear to contribute to the reduced bone level on the central incisor adjacent to the cleft.
Sound- and surface electro-myography of human jaw elevator muscles D. C. Pham University of Tennessee, Memphis, Tenn., 1991.
The three objectives of this study were (1) to study the relationship between isometric incisor bite force and the surface electromyogram (EMG) and the sound myogram (SMG) from four jaw elevator muscles, (2) to determine the amplitude and frequency content of SMG detected during isometric incisor biting, and (3) to evaluate the relationship between bite force and different measures of craniofacial morphology obtained from the lateral cephalogram. SMGs and surface EMGs were obtained from anterior temporalis (bilateral) and masseter (bilateral) muscles at six levels of incisor bite force (0% to 30% maximum voluntary contraction, or MVC) for 13 subjects. Each force level was maintained for 4 s; digitzation occurred at 256/s. For the different subjects, and for a constant incisor gape, the magnitude of the 30% MVC incisor bite force was correlated with: (1) the EMG level at 30% MVC; (2) the Frankfort mandibular angle; (3) the palatal plane angle; (4) the gonial angle; (5) the lateral area of masseter muscle; (6) the coronoid process area; and (7) the masseter angle. There was a nearly linear, positive relation between rms EMG and bite force. SMG amplitude (rms) increased to a maxinmm at a low force level and remained constant or decreased for higher forces. For SMG spectra, frequency components ranged from 5 to 30 Hz with one or two major bands present in both mandibular muscles. Two bands, if present, had peak frequencies between 10 to 14 Hz and 15 to 20 Hz. SMG spectra indicated a shift toward higher frequencies with increased tension. The SMG may not be useful as an indicator of force (or fatigue) of jaw muscles.