Fixed partial denture retainer

Factors affecting the fixed dentures

1. The arrangement relationship of the maxillary and mandibular teeth: maxillary fixed partial denture.

Mandibular teeth push the upper teeth to move the lips and the buccal force, especially in the anterior maxilla. Maxillary fixed partial dentures affected.

Mandibular teeth arranged in axial direction is more vertical, is exposed to the occlusal more vertical, mesiodistal and buccolingual prevent mandibular teeth to shift. Mandibular denture affected is small.

2. Abutments by the force of movement: buccolingual and vertical movement, near and far to the movement.

(1). Buccolingual movement: when the fixed bridge is balanced by the buccal or lingual occlusal force to the two abutment teeth by the first type of leverage, the formation of the rotary motion of the tongue or cheek to the fulcrum is located in the root apex of two basic / 3 1/3 of the root of the intersection of the connection. If both ends of the abutments solid, good retention force of the retainer, a fixed bridge retainer.

If one end of a fixed bridge from the cheek side of the tongue lateral external force, the abutment itself will be the role of first-class lever, the crown to the buccal move, while the root tip moved slightly to the tongue side of the fulcrum is located in the apical 1 / 3 and root 1/3 at the intersection. At this point, a. If both ends of the abutment teeth than the solid, the rotational movement of the fixed bridge is small, less impact on retention. Two. If both ends of the solid body retention force disparities, the small end of the retention is very prone to loosening. 3. Two abutment periodontal condition disparities, can easily lead to poor conditions at one end of periodontal tissue damage, leading to tooth mobility.

Therefore, the fixed partial denture design, both ends of the abutments supportive with retention retentive force should be almost equal.

(2). Near and far to the sport: When fixed partial dentures are nearly in the direction of the oblique external, two abutments will shift nearly in the center to the apical 1/3 and 1/3 of the root of the intersection of the root tip slightly to the distal shift, all the external force to support the ridge on the far edge of the abutment crown occlusal crown height of less than or dental supplies shaft wall excessive cohesion, retention due to the movement of the abutment loosening from the abutments, resulting in and loosening of the fixed bridge.

Under normal circumstances the amount of movement is very small, due to the nearly adjacent teeth. However, if the abutment is not good, loose teeth, or Porcelain teeth rework some of the problems when the force is too large, the above will occur.

(3). Perpendicular to the movement: the stability of the fixed partial denture is fixed partial dentures in chewing movement to withstand occlusal forces from all directions, to maintain the equilibrium potential of Alice. Denture force generated when the lever force, which denture ability to obtain good retention has a close relationship.