Abstract
A nine year and six month old boy with the Hallermann-Streiff syndrome was examined morphologically and functionally from a dentalpoint of view, and the following findings were obtained.
1) Microdontia of all of the deciduous teeth and persistence of many of the deciduous teeth were noted. Congenital missing of many of the permanent teeth was also seen.
2) The occlusal relationship indicated unstable and open bite.
3) According to X-ray cephalometric analysis, the mandible rotated clockwise and the length was short.
4) According to X-ray cephalometric and CT analysis, bilateral missing of the mandibular condyle and bilateral hypoplasty of the tuberculum articulare were found.
5) The mandibular kinesiograph revealed that the route and convergence were not stable during the mandibular border movement, and that the convergence and rhythm during the tapping movement were also unstable.
6) According to the electromyography of the masseter and temporal muscles, (a) the amplitudes and durations were not stable, and the durations of the silent periods were unclear during the tapping movement (b)the muscular activities were simultaneous and regular during mastication.
