Achieving optimal esthetics while maintaining retention, stability and healthy tooth structure has always been a challenge with cast partial dentures. Patients demand cleaner, brighter and more perfect teeth no matter what the restorative situation. Yet, the use of clasps resulted in highly visible metal display, drawing attention to the restoration. In the past, the only real esthetic alternatives for dental professionals were to go through the expense and technical difficulties involved with incorporating precision attachments into the prosthesis or cutting down healthy natural teeth for use as abutments. Now, through “technique” (i.e., the principles of Esthetic Design) and “technology” (those principles applied as the Saddle-Lock “Hidden Clasp” partial denture system), visible metal display can be eliminated.

Saddle-Lock “hidden clasp” Vitallium® 2000 cast partial.   Unsightly old conventional clasp upper partial denture. Completely tooth-borne upper partial denture.

Technique – The Benefits of Esthetic Design

Certainly, when we refer to esthetic design in cast partials, we are referring to the elimination of visible facial display of the metal retentive clasp arms. However, there are many additional benefits to the esthetic design approach:

• Superior retention. Normal tooth contour provides a more dependable and usable undercut on the proximal surfaces than on the facial or lingual surfaces.
• Gentler on abutments. Both the rest placement and retention area used reduce stress on the abutment tooth during normal functions.
• Superior function. The retentive clasp is activated to resist lift of the appliance due to tacky food during chewing compression and does not transmit stress to the tooth.
• Durability. Esthetic designs function longer without problems. The cast partial does not bend or torque during function. This reduces work hardening and resulting clasp breakage.

Technology – Saddle-Lock™

With the Saddle-Lock “Hidden Clasp” partial denture system from Aurum Ceramic/Classic, clasp retained cast partials can be crafted without visible metal display. And, with the improved handling characteristics and advanced physical properties of Vitallium® 2000 and Vitallium® 2000 Plus alloys, it is possible to create a smaller, lighter partial dentures with extraordinary strength and superior fracture resistance.

Saddle-Lock uses the more pronounced natural mesial and distal undercut planes of the abutment teeth adjacent to the denture saddle. This allows stress to be shared by the adjoining teeth as forces are distributed in an anterior-posterior direction. Clasp emergence is back at the casting finishing line providing proper resiliency. The clasp terminals are positioned at the end of the denture saddle, effectively locking the segment to the ridge. Accurate measurement and paralleling of the planes using the “Retentoscope” (a precise survey and design instrument) ensures each abutment tooth has a comfortable, yet positive load. Saddle-Lock also handles inadequate retention and instability in free-end saddle cases. The retentive clasp force located in the distal undercuts transmits its stabilizing force into the loose end segment of the denture resisting dislodging forces during mastication.

Conclusion

In almost any clinical situation, unsightly metal clasps no longer need to be a challenge. Cast partial prostheses can now be created to meet the most exacting functional and esthetic demands.