How to achieve ideal preparations for successful all-ceramic crown restorations

Komet USA’s seven-instrument crown-preparation kits have been developed to meet the challenges and practicalities of preparations for all-ceramic crowns.

The instruments in the LD1316 kit are systematically organized to create ideal modified-shoulder preparations with rounded, internal angles. Likewise organized, the contents of LD1487 kit permit distinct chamfer preparations to be accomplished with predictability, reliability and efficiency. Proper application of the instruments in either kit allows the precise reduction of crown contours to ensure precise impression-taking (by scanning or traditional methods) and successful fit of the final crown restoration.

Both kits include the Komet® S5858 contact breaker for interdental separation, the egg-shaped S6379 S-Diamond® for occlusal/palatal preparation and the 843KRA occlusal depth-guide diamond. The LD1316 modified-shoulder prep kit also provides two tapered, round-edge 847KR S-Diamonds and two corresponding finishers, while the LD1487 chamfer-prep kit provides two tapered, round 856 S-Diamonds and two corresponding finishers. The instruments in each kit are conveniently arranged in a Komet® stainless-steel bur block to simplify access, selection and post-use instrument processing.

Watch the video below to learn how to achieving ideal preparations for successful all-ceramic crown restorations with Komet® instrument kits LD1316 and LD1487.

Fig. 1. Create a stump with a 4-to-6-degree cone. Round off all transitions within the preparation to prevent potentially damaging tension beneath the restorative material.

Fig. 2. If the position of the tooth requires no correction, reduce the outer contour of the crown by 1.5 mm, the occlusal surface by 1.5-2.0 mm and the margin by at least 1 mm without mimicking the crown equator. To ensure an optimal fit of the all-ceramic crown restoration, take care to eliminate all sharp edges and corners.

Fig. 3. Make certain the preparation limit has a width of at least 1.0 mm.

Fig. 4. Create a shoulder preparation with rounded interior angles (Kit LD1386) or a distinct chamfer preparation (Kit LD1487). Rework the preparation margin with finishing instruments of matching shape (with red-ring identifier).

Fig. 5. Avoid tangential, spring-edge or lip preparations.

Fig. 6. For occlusal depth marking, use instrument 843KRA, which features a 2-mm-long working end and a short shank.

Fig. 7. Employ a silicone index to verify that sufficient substance has been removed.

Fig. 8. Round off all sharp edges and corners to complete the preparation for an all-ceramic crown restoration.

For more information on the Komet® LD1316 modified-shoulder prep kit and the LD1487 chamfer-prep kit, contact Komet USA LLC at 888-566-3887 or visit the company website at www.kometusa.com.