CHAPTER 11 Case Presentations
Alternatives for Final Framework Designs
A hybrid prosthesis is a prosthesis that replaces missing teeth and missing soft and hard tissues in a composite defect. The term hybrid prosthesis (or the Brånemark or Toronto bridge) has become synonymous with a metal-based prosthesis that replaces missing soft and hard tissues with pink acrylic and missing teeth with acrylic teeth. If the restorative dentist so chooses, pink porcelain and porcelain teeth may be substituted for the restorative reconstruction using the hybrid treatment concept.
The design of the hybrid prosthesis has evolved with the advent of new abutments such as the multiunit abutment, which allows a more natural and anatomically correct emergence of the prosthesis from the soft tissues. Today, these prostheses are referred to as profile prostheses.
The Toronto bridge was a “high water” design because the abutments available at the time were standard abutments, which, by design, were at least 0.5- to 1-mm supragingival. Therefore, the final design of the prosthesis left a gap between the intaglio surface of the prosthesis and the crest of the ridge. This type of design was functional for the edentulous mandible. When turned upside down and used for the edentulous maxilla, however, it left a lot to be desired. The gap allowed air to escape during speech and caused mispronunciation of dentoalveolar sounds. Proper pronunciation requires a palatal seal between the prosthesis and the palatal soft tissues (Figures 11-1 and 11-2).
FIGURE 11-1 The maxillary hybrid prosthesis: The existing space between the intaglio surface of the prosthesis and the soft tissues does not allow for proper phonetics in the edentulous maxillary arch.
The intaglio surface of the profile prosthesis has a cross-section similar to a pontic tooth in a conventional fixed partial denture. Pink acrylic surrounds a metal substructure and meets the soft tissue crest with pinpoint contact. This seals the gap, and phonetics in the maxillary profile prosthesis are acceptable.
An important feature of the profile prosthesis is the design of the metal substructure. Whether gold or titanium framework is used, extension of the framework to support the overlying pink acrylic and teeth is crucial. To allow the laboratory technician to design a metal substructure with adequate extensions in both the anterior-posterior (AP) and lateral dimensions, the initial step in profile prosthesis design involves setting acceptable denture teeth. Proper extension of the metal framework permits well-supported occlusal loads, which prevents teeth from “popping off” during function.
FIGURE 11-3 A, Clinical presentation of the “profile prosthesis” as it relates to the edentulous soft tissues. B, The maxillary profile prosthesis: The interimplant pink acrylic wraps around the metal substructure and is in pinpoint contact with the soft tissue of the maxillary ridge.
FIGURE 11-9 The severe posterior resorption of the maxillary ridge does not allow any landmark to assist the laboratory technician in extending the framework. Use of the putty index permits this maxillary framework design to have proper extensions.
A 43-year-old woman with nonrestorable maxillary dentition presented for definitive treatment of her maxilla with an implant-supported prosthesis. Her clinical evaluation resulted in the following findings:
FIGURE 11-21 Removal of the existing maxillary teeth with immediate placement of implants. Immediate loading is considered after reaching 40 Ncm. The decision was made to incorporate four of the six implants into the provisional prosthesis.