Hiroko Nakahara

Somatosensory-evoked Fields for Gingiva, Lip, and Tongue

To localize the oral primary somatosensory cortex, we measured somatosensory-evoked fields for the lip, gingiva, and tongue in six healthy subjects. The latency of the first peak of the posterior-oriented current in the contralateral hemisphere was 50.9 ± 8.3 ms for the gingiva, significantly shorter than those for the lip and tongue peaks. The equivalent current dipole was localized on the central sulcus. The gingival dipole was localized significantly inferior to the lip dipole but not different from the tongue dipole. The moment of the gingival dipole was significantly smaller than that of the lip dipole but not different from that of the tongue dipole. Differences in the above parameters were negligible between the left and right, anterior and posterior, and upper and lower locations within the same organ, except that the dipole location for the anterior upper tongue was significantly inferior to that for the lower tongue.

Biomechanical comparison of straight and staggered implant placement configurations

The effect of buccolingual staggered implant placement on stress distribution within the supporting structure was examined photoelastically. Two photoelastic models of a human mandible, edentulous distal to the canine, were fabricated. Three screw-type implants were embedded into the edentulous region of each model. The implants were placed in a straight line in one model and in a buccolingual staggered configuration in the other. Vertical and lateral loads were applied to a fixed partial denture superstructure. No clear biomechanical advantage to a staggered 1.5 mm buccal and lingual offset placement configuration was observed.