Many investigators have studied on influences of preparation of vital teeth and associated prosthetic treatments on the pulp. Only a few, however, have referred to discomforts which patients actually suffered.
In this study, patient's discomforts after preparation were investigated. The material consisted of 119 vital abutment teeth that were prepared for fixed bridges on 77 patients at the Students' Clinic of Tsurumi University.
Furthermore, the follow-up examination was held 6-14 months after final cementation.
The results were as follows:
1. 19 teeth (16%) exhibited discomforts such as hypersensitivity against cold foods or pain while occluding. Through application of diammine silver fluoride and/or occlusal equilibration, the discomforts in 18 teeth were cured, but the pulp of one tooth had to be removed.
2. Concerning sex, age and types of teeth with discomforts, higher frequency was found in women, in fifties and at upper premolars and lower molars.
3. 9 patients complained first at the stage of preparation and 10 patients just at the stage of temporary fixation of bridges. There were no patients who felt discomforts first after final cementation.
4. Duration of discomforts ranged from within 2 weeks to over 8 weeks at almost the same proportion.
5. The teeth which displayed discomforts once were in worse situation than the control, according to the follow-up examination.

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Experimental crowns with uniform thickness at their axial surfaces were made of dental casting goldsilver-palladium alloy (12 % gold) and dental casting gold alloy (Type IV) . They were cemented on model teeth for abutment and their deformations under applied loads were measured with strain gages. The effect of axial metal thickness on the crown's rigidity and the cement fracture strength were examined. Among the structures of cemented crowns and abutment teeth, that of the axial metal thickness of 0.3 mm had cement failure at the smallest loads. As the metal thickness was increased, the crown's deformation decreased and the cement failure load increased. For a thickness greater than 0.7 mm, however, the increase in failure load was not obvious. The difference of the casting alloy had no significant effect on the cement fracture. Accordingly, the rigidity of dental prostheses should be one of the most important design factors for preventing failure under occlusal load, and it is recommended that the thickness of the axial surface should be more than 0.7mm.

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EMG activities of sternocreidomastoid and trapezius muscles during the isometric maximum voluntary exercises of the head, neck, shoulder, back and mandible were studied in 10 healthy examinees.
These results obtained were as follows:
1. In the sternocreidomastoid muscle, the mean of integrated EMG values showed its maximum on the exercise of the head in which one rotated his mentum contralaterally-rostally forward; in the nuchal and shoulder regions of the trapezius muscle, on the exercise in which one raised his shoulder rostally; and in its back region, on the exercise in which one pulled his shoulder backward.
2. In average, the rates of integrated EMG value on the mandibular exercises to the maximal value on the head, neck, shoulder and back exercises were 9.2 and 19.6% in the superior and inferior regions of the sternocreidomastoid muscle, and 15.4, 1.1 and 8.4% in the nuchal, shoulder and back regions of the trapezius muscle, respectively.
3. These results were discussed in relation to unpleasant sensations on the neck, shoulder and back regions in occlusal diseases.

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In order to clarify the influence of the examiner's standing position during palpation (right side of simulation model: PR, central: PC, left side: PL) on the palpable pressure speeds of fingers, 10 dentists of 10.3 year-mean clinical experience were examined for palpable pressure speeds of second fingers (F 2) and third fingers (F 3) of left (L) and right (R) sides of a simulation model.
The following results were obtained.
1. Palpable pressure speeds of F 2 and F 3 were influenced by the examiner's standing position.
2. For both F 2 and F 3, pressure speed was higher for L than R in PR and for R than L in PL or PC.
3. Pressure speeds of F 2 and F 3 in PC showed small laterality.
4. Palpable pressure speeds of F 2 and F 3 showed greater laterality in PR and PL than in PC.

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