Clinical application of stress-breaking ball attachment for implant overdenture

Patient: The patient was a 62-year-old partially edentulous woman with missing bilateral premolars and molars in the mandibular jaw. The patient selected implant supported-removable partial denture rehabilitation. Implants were placed bilaterally at the distal extension of the denture base in order to minimize denture displacement. The stress-breaking ball (SBB) attachment consists of a flat-top ball head male and O-ring rubber female. The female was covered by a silicone housing with three amounts of space to allow three kinds of settlement (0.3. mm, 0.5. mm, and 0.7. mm); they were selected by thickness or pressure displacement of the mucosa and occlusal force. After the healing period, the SBB attachments (0.3. mm) were placed on the implants, and the implant-supported removable partial denture was then conventionally fabricated. The delivered denture had sufficient retention and appropriate stress breaking. Discussion: The advantages of SBB attachments over conventional attachments are as follows: (1) they prevent the implant from excessive occlusal force, (2) they are ready-made, (3) they show appropriate retention, and (4) they can be easily mounted on the denture base. The disadvantages of these attachments are as follows: (1) they are approximately 1. mm higher than conventional ball attachments and (2) the retentive force cannot be adjusted. Conclusion: The use of a stress-breaking attachment for implant overdenture rehabilitation should be considered so that the occlusal force is equally distributed between the alveolar ridge and the implants. © 2012 Japan Prosthodontic Society