Displacement of the teeth and mandibular bone resulting from lateral loading
1996 Volume 59 Issue 4 Pages 356-364
Details
1996 Volume 59 Issue 4 Pages 356-364
A mandible removed from a dog was fixed in super hard plaster so that the long axis of the first molar was perpendicular to the surface of the foundation, loads were imparted at various angles to the lingual of the first molar, and displacements of the tooth and the surface of the mandibular bone were observed with holography. The load was imparted in the horizontal plane at angles of 30, 45, 60 and 90 degrees to the buccal surface of the first molar, which corresponds to the mesiodistal direction of the tooth. For each of these four angles, the load was imparted in the vertical plane at 30, 45 and 60 degrees with respect to the long axis of the first molar. Thus, the load was imparted from a total of 12 directions.
A fringe of straight lines in the first molar running from the distal/superior to mesial/inferior direction appeared that showed a larger displacement in the mesial than in the distal region. As the direction of the load moved towards the distal, the inclination of the fringe tended to become greater. This indicates there was rotational displacement of the tooth. Furthermore, when the angle with the long axis of the tooth decreased from 60 to 30 degrees, that is, as the direction of the load moved towards the horizontal, there was an increase in the number of fringe lines. This shows that forces from the horizontal direction caused marked displacement in the tooth.
A primary fringe of circular arcs first appeared on the surface of the mandibular bone in a location corresponding to the tips of the roots. As the direction of the load moved towards the horizontal, the fringe moved towards the cervical region, and a secondary fringe appeared where the primary fringe had first been observed. This effect became more pronounced as the direction of the load moved towards the horizontal.
From the above experiments, we were able to obtain displacement patterns for the teeth and mandibular bone that resulted from lateral forces. Shika lgaku (J Osaka Odontol Soc) 1996 Dec; 59(4): 356-364.
