No abstract

Abstract.The effects of thyroidectomy on patterns of TRH and somatotropin release-inhibiting factor (SRIF) release from the hypothalamus were investigated by using a microdialysis technique. Thyroidectomized and sham-operated rats underwent placement of a guide cannula into the anterior pituitary gland to obtain dialysates, or implantation of an intravenous cannula into the right atrium for blood sampling.Seven days postoperatively dialysates were collected at a flow rate of 2 p1/min every 1 h. TRH concentrations in dialysates from thyroidectomized rats (0.43 ± 0.22 pg/h) were significantly higher than those from control rats (0.17 ± 0.02 pg/h).In contrast, SRIF concentrations in dialysates from thyroidectomized rats (2.45 ± 0.05 pg/h) were significantly lower than those from control rats (3.80 ± 0.22 pg/h).In addition, plasma TSH concentrations in thyroidectomized rats (24.8 ± 0.5 ng/ml) were increased compared with those in control rats (2.5 ± 0.1 ng/ml), and plasma GH concentrations were decreased from 68.6 ± 6.4 ng/ml in control rats to 21.2 ± 0.6 ng/ml in thyroidectomized rats. These findings indicate that TRH and SRIF releases from the hypothalamus are detectable by microdialysis method, and directly show the increase in TRH secretion and the decrease in SRIF secretion from hypothalamus in the hypothyroid state.

Magnetic overdenture attachments can provide useful denture retention. A technique is proposed that involves installing the magnetic keeper in the overdenture abutment coping using laser welding. Compared with the conventional cast-to technique, the new technique provides a suitable contour to the abutment coping with the magnetic keeper and ensures proper mounting in the abutment coping, installing the magnetic keeper easily and effectively.

No abstract

Abstract:Mastication and swallowing are closely related to tongue function. In the elderly, decrease of tongue function is suspected to cause oral malfunction. The purpose of the present study was to clarify the aging of swallowing by observing tongue pressure on the palate during swallowing. The subjects used were three young dentate persons and eight elderly complete denture wearers. Five pressure transducers were placed in either the artificial palatal plate or the duplicated upper denture. Tongue pressure and electromyography (EMG) of the suprahyoid muscle were recorded.The results were as follows : 1. Maximum tongue pressure of the elderly denture wearers was significantly lower than that of young dentate persons. 2. Upon swallowing saliva, both the duration from the EMG onset of suprahyoid muscle movement to the onset of tongue pressure and from the EMG onset to the time of maximum tongue pressure of the elderly were longer than those of the young dentate persons.3. In young dentate persons, the duration from the onset of tongue pressure to the time of maximum tongue pressure in swallowing saliva was shorter than that for swallowing 2 ml water, while that of elderly denture wearers was longer.

Magnetic overdenture attachments can provide useful denture retention. A technique is proposed that involves installing the magnetic keeper in the overdenture abutment coping using laser welding. Compared with the conventional cast-to technique, the new technique provides a suitable contour to the abutment coping with the magnetic keeper and ensures proper mounting in the abutment coping, installing the magnetic keeper easily and effectively.

No abstract

In the previous report, the relative position between two implants was measured during jaw movements, and mandibular flexure was evaluated as the change. In the present study, three-dimensional finite element models were constructed so that six titanium implants were placed in the right half of the mandible, and three models were prepared: 1) Connected: all implants were connected, 2) Anterior only: anterior three implants only were connected, and 3) Not connected: no implant was connected. The influence of the connection on the implant and the surrounding bone determined by linear static stress analysis of 3-D finite element model was discussed. The results were as follows: 1. The inside loading value applied to the mandibular condyle was calculated from the implant deviation data of previous reports. The value was 20 N. 2. In three models the implant was deviated medial-backward and the deviation drastically increased from the Implant No. 4 region. 3. The stress of 8 MPa around the implant in the "Not connected" model was observed, and that of "Anterior only" and "Connected" models was lower. It was suggested that implant connection hardly affects the implant and the surrounding bone during mandibular flexure in jaw movements.