Thursday, September 1, 2011

Posterior Proximal Contours & Contacts ROE Standards

It is the mutual goal of both dentist and laboratory to create lifelike restorations that seat efficiently and satisfy patients. When seating posterior restorations, the primary determinants of success are interproximal and occlusal contact, contour, shade, and marginal integrity. Of these, interproximal contact is a subject we often discuss with our clients. We thought it would be helpful to share our “standard” for contact design in the following drawings and descriptions, which we have found satisfi es the majority of our clients. If you prefer a different design please use this reference as a guide to communicate your preferences. This information, added to your “customer profile,” will enable us to always meet your expectations.
 
1. Contacts should be football-shaped and located below the marginal ridge. The ROE standard is to establish broad, rather than point contact. Note how the surface area of the contact is approximately 1/3 the width of the occlusal table. The ROE standard for tightness is for the restoration to “hold” shim stock (12 microns) when fully seated on the solid model. 

 
2. Some dentists request extra broad contacts and want contours as shown from this occlusal view. X and Z show ideal contour while W and Y show “extra-broad” contact. The image to the lower left shows the proximal view, and the outline in red indicates the broadened contact. 


3. From an occlusal perspective, contact between the cuspids, bicuspids and 1st molars should be placed 1/3 lingual and 2/3 buccal so the embrasures are deeper on the lingual than the buccal. The contact between the 2nd and 3rd molars is placed approximately 1/2 buccal and 1/2 lingual. 





4. Proximal surfaces gingival to the contacts should be contoured so the embrasure is symmetrical and triangular in shape, as indicated in red. 






5. This diagram shows an under-contoured buccal embrasure as indicated by Y. Proper contour is shown with the dotted line indicated by X. 





6. From a gingival–occlusal perspective, contacts are positioned as shown. Maxillary posterior contacts move progressively towards the gingiva as they move away from the midline, while mandibular posterior contact points are at the same general level or plane. 

Special thanks to Dr. William Sweeney Jr. for his contribution to this article.

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