Stress-Breaker for Unparallel Bridge Abutments

 

Use when the abutments--either prepped teeth or implant abutments--are not parallel and require an attachment for independent seating of the crown and/or bridge

The benefits include: 

  • Bridge segmentation allows for reduced tooth reduction and independent seating and cementation.
  • It is easier to overcome parallax by preparing groups of abutments parallel to each other than an entire arch.
  • Cementation of a segment is easier and more accurate than cementation of a long span bridge.  The hydraulic resistance of cement exponentially increases with multiple units.
  • Bridge segmentation eliminates potentially pathologic cross arch forces. When a force is applied on the left side of a full arch bridge (in a natural dentition, the periodontal ligament allows for minor physiological movement) a potential pathologic lifting force is transferred to abutments on the right side of the arch.
  • Extensive mandibular long span bridges can reduce the ability of the mandible to flex, causing trauma to the abutments.  This is accentuated in mandibular implant supported bridges as there is no implant mobility to offset abutment rigidity and allow normal flexing of the mandible

 

There are two types of stress-breakers, which are explained below.

  • Rod and Tube attachments are taller and narrower--just like anterior teeth--and thus are used commonly to splint anterior teeth.  The attachment design allows for esthetic incorporation into the contours of the crown/bridge.  Less bulk is required in the anterior due to reduced forces. 
  • Dovetail attachments are commonly used for posterior segmentation.  Like posterior teeth, these attachments are shorter and wider to allow for both esthetic incorporation as well as withstand the increased posterior masticatory forces.  When maximum esthetics are required, simply Invert the attachment--place the male on the abutment and the female inside the pontic.  This eliminates showing metal, and when used in the mandible, allows flexure.

Information and photos courtesy of PREAT Corporation.