Studies on the influences of the indirect retainers on the displacements of the denture bases and the abutment teeth. 2. The forms and locations of indirect retainers used for cross arch stabilizations

: The purpose of this experimental study is to investigate and evaluate characteristic movements of the denture bases and the abutment teeth, when the forms and locations of the indirect retainers used for the cross arch stabilization are altered. The results are as follows: 1. Under the vertical forces, the increases of abutment tooth excursion and denture base movement are observed, when the fulcrum line crosses the "loading axis" at nearly right angle. 2. When the vertical forces are applied, the displacements of abutment tooth and denture base with two indirect retainers are more reduction than that with one. 3. The distances between two indirect retainers used for cross arch stabilization increase, the less displacements of abutment tooth and denture base are. 4. When the partial denture has only one indirect retainer used for the cross arch stabilization, it is important that the positive rest is located on the anterior tooth and the indirect retainer is placed on as distal tooth as possible. 5. If the occlusal forces are supported by the residual ridge, it may be better designs that the positive rest is located on the anterior tooth and the Akers clasp with mesial rest or the double Akers clasp is located on the premolars.