Replicability of electromyographic recordings of the masseter muscle during mastication

This study evaluates the reliability of a method to duplicate the location of surface electrodes for recording the electromyographic activity of masseter muscles during mastication and quantifying the activity by a microcomputer system. A plastic framework consisting of a bite fork and electrode positioners was used to place the electrodes by relating the positioners to an occlusal index and keeping this relationship constant at subsequent sittings. EMG recordings were repeated on two different days for each of 10 subjects while they performed standardized masticatory performance tests with peanuts and carrots. The muscle activity recorded with hardware integrators was an average of 26.7% of the computerized software integrations but measures derived from the two methods of integration were highly correlated (r = 0.965) and yielded similar results. Significant correlations were found between test sessions for each measure of masticatory performance and integrated EMG activity for ipsilateral and contralateral muscles. For each subject, no significant differences were found between sessions for any masticatory performance or EMG variable. The results indicate that reliable inter session EMG recordings during mastication can be made by using the template for positioning of the electrodes. In addition, the microcomputer data acquisition system provides results comparable to those obtained with conventional hardware integrators, with the added benefit of providing information on each individual stroke and its various components.     

Anticipatory and reflexive neck muscle activities during voluntary rapid jaw opening and passive jaw depression in humans

The characteristics of head movement during voluntary rapid jaw opening movement and passive jaw depression were investigated using accelerometers and electromyographs (EMG) on eight healthy examinees. Passive depressions were executed by means of load on the lower jaw, initiated either by examinees themselves or an experimenter. In the depression initiated by examinees, a head-extension movement that preceded the load to the lower jaw and anticipatory activities in the nuchal region of the trapezius muscle were observed. In the depression initiated by the experimenter, the anticipatory activities were not observed. In both of these cases, stretch reflexes were induced in the trapezius muscle. During voluntary rapid jaw opening, a head-extension movement nearly synchronized with the opening movement in the lower jaw acceleration, and dorsal-neck muscle activities accompanying the synchronized movement were observed. The peak timing of these neck-muscle activities preceded the latencies of the stretch-reflex activities observed in the jaw-depressed tasks, but no anticipatory activities were observed in the dorsal-neck muscles. We conclude that neither the anticipatory activities nor the reflex activities observed in the passive depressions have effects on the initial part of the dorsal-neck muscle activities, which are related to the head-extension synchronized with the voluntary lower-jaw opening movement.     

Opinions of dentists and directors of nursing concerning dental care provision for Adelaide nursing homes

BACKGROUND: The complex oral health problems of nursing home residents have been well documented. However, the influences on residents' oral health status, including opinions and experiences of dental professionals and nursing home staff, have not yet been adequately investigated. METHODS: The baseline questionnaire component of this longitudinal study was mailed to all registered dentists practising in Adelaide and Adelaide nursing home directors of nursing (DONs). RESULTS: 413 dentists and 97 DONs indicated that Adelaide dentists' interest and training in nursing home dentistry was low. Dental service provision for nursing home residents was very low and dentists preferred to provide treatment at their dental practices. Few dental hygienists were working in nursing homes and dental professionals provided little educational assistance for nursing home staff. Dentists and DONs held several common and many varying perceptions of the problems associated with dental care provision in nursing homes. Both identified a group of nursing home environmental constraints and a lack of portable dental equipment. DONs further identified a group of resident related problems, and dentists a group of dental practice-related problems. CONCLUSIONS: These study results provide important information concerning problems with nursing home dentistry for dental service providers, educators, policy-makers, administrators and nursing home staff.     

Neuromuscular relaxation and CCMDP. Rolfing and applied kinesiology. 3

The structural and functional connection between stomatognatic system, rachid, pelvis and lower limbs are well known; it's obvious that an alteration in one of these districts influences the other ones. Rolfing and applied kinesiology, on this ground, work to resolve muscular pain in cranio-cervicomandibular syndrome.     

Modulation of oligosaccharide processing in an exocrine secretory glycoprotein of rat parotid cells by beta-adrenoreceptor activation

Such stimulation of rat parotid acinar cells in vitro modulated the rate of processing of N-linked oligosaccharides in a high-molecular weight (220 kdalton) secretory glycoprotein. Conversion of polymannose-type oligosaccharides to complex-type oligosaccharides was evaluated by sensitivity to endoglucosaminidase H and alpha-mannosidase, and with a specific inhibitor of glucosidases I/II. Oligosaccharide maturation in the 220 kdalton glycoprotein required one-third to half less time in cells exposed to the beta-adrenergic agonist isoproterenol than in controls.     

Delayed healing of fractures of the mandibular body

401 mandibular body fractures occurring during a 5-year period were analysed retrospectively. Out of these, 38 fractures (9.5%) were not consolidated by 50 days and made up the delayed healing group (DHG). A control group (CG) of another 38 fractures was constituted using the first mandibular body fracture consecutively following one in the DHG. The mean time until consolidation of the fractures was 116 days in the DHG and 35 days in the CG. The 2 groups were statistically analysed and mutually compared using a great number of variables including patient-, fracture site-, treatment- and end-result characteristics. It was concluded that a few days delay between trauma and treatment did not necessarily lead to a delayed healing. Uncooperative alcoholics with psycho-social handicaps, and general as well as local periodontitis, were found to be especially liable to consolidate their fractures at a slower rate than the average patient. The DHG more often required changes of unstable dental fixation, prolonged maxillo-mandibular fixation time and treatment for late infections at the fracture site. The patients in this group lost more teeth than those in the CG but above all required considerably extended therapeutic efforts. It is suggested that patients with the above-mentioned characteristics should be given special attention and care.     

Porous hydroxylapatite as a bone graft substitute in mandibular contour augmentation: a histometric study

The buccal contour of the mandible was augmented in 17 dogs with 5 X 7.5 X 20 mm blocks of porous hydroxylapatite (HA) on one side and two-layered split rib autografts on the other. Both specimens were retrieved at three, six, 12, 24, and 48 months. Undecalcified sections were prepared for microradiography, light and UV microscopy, and histometry. A transmitted light video image digitizing system was used to trace implant and graft perimeters and calculate cross sectional areas. This system was also used to measure graft density and calculate bone and soft tissue compositions. The HA matrix, bone and soft tissue compositions of implant specimens were measured with a backscattered scanning electron microscope imaging digitizing system. All grafts became increasingly resorbed with time whereas all implants remained intact. Mature osteotonic bone ingrowth was present in all implants except one which failed to unite with the mandibular cortex. The mean graft areas decreased from 30.8 mm2 at three months to 0.7 mm2 at 48 months, while the implant areas averaged 35.5 mm2 and remained stable. The graft specimens were composed of 46.6% bone and 53.4% soft tissue or fluid space. The implant specimens were composed of 34.5% HA matrix, 28.6% bone, and 33.9% soft tissue. The HA matrix had a surface area of 9.8 mm2/mm3 that was 61.9% covered with bone ingrowth and 38.1% covered with soft tissue or fluid space. In contrast to the rapid resorption of graft onlays, the porous HA matrix demonstrated a long-term permanence with maintenance of contour and osseous incorporation over the four-year duration of this study.